The Synthesis and Characterization of [RuII (bpy) 2 ...

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1995

The Synthesis and Characterization of [RuII (bpy)2 (biphen) ] (PF6)2 and [ (bpy) 2RuII (biphen)RuII (bpy) 2] (PF6)4Mei-Yueh ChangEastern Illinois UniversityThis research is a product of the graduate program in Chemistry at Eastern Illinois University. Find out moreabout the program.

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Recommended CitationChang, Mei-Yueh, "The Synthesis and Characterization of [RuII (bpy) 2 (biphen) ] (PF6)2 and [ (bpy) 2RuII (biphen) RuII (bpy) 2](PF6)4" (1995). Masters Theses. 1966.https://thekeep.eiu.edu/theses/1966

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The Synthesis and Characterization

of [Ru II (bpy) 2 (biphen) ] (PF 6 ) 2

and [ (bpy) 2RUII (biphen) RuII (bpy) 2] (PF5) 4

(TITLE)

BY

Mei-Yueh Chang

THESIS

SUBMITIED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS

FOR THE DEGREE OF

MASTER OF SCIENCE IN CHEMISTRY

IN THE GRADUATE SCHOOL, EASTERN ILLINOIS UNIVERSl1Y

CHARLESTON, ILLINOIS

1995 YEAR

I HEREBY RECOMMEND THIS THESIS BE ACCEPTED AS FULFILLING THIS PART OF THE GRADUATE DEGREE CITED ABOVE

7-2 /-C,{"" DATE

DATE

The Synthesis and Characterization of

[Ru11 (bpy2 ) (biphen)](PF6 ) 2 and

[(bpy) 2Ru11 (biphen)Ru11 (bpy) 2 J (PF6 ) 4

Thesis Approved

}-Z/- 1J.-

Abstract

A new bidentate polypyridine bridging ligand (biphen),

produced by the condensation of 1,10-phenanthroline-5,6-dione

with 5,6-diamino-phenanthroline has been synthesized and

characterized. In addition

[ (bpy) 2RUII (biphen)] (PF5) 2 and

the

the

monometallic

bimetallic

complex

complex

[ (bpy) 2Run(biphen)Run(bpy) 2] (PF6 ) 4 have been prepared. The

complexes were characterized by elemental analysis, by 1H-NMR

spectroscopy and by cyclic voltsmmetry(CV).

The results of these analyses seem to indicate that

biphen acts like two independent units when attached to a -

Run (bpy) 2 fragment. a bipyridine portion and a phenazine

portion. Moreover, CV data on the bimetalllic complex

indicated no special stability for the mixed-valence form,

ruling out any significant metal-metal interaction.

ACKNOWLEDGEMENT

I would like to express my sincere appreciation to Dr.

Mark E. McGuire, my research advisor, for his patience and

help during this study.

I would like to thank the faculty and staff of the

Chemistry Department of Eastern Illinois University and

Kaohsiung Noble University and the other members of our

research group for their encouragement and assistance.

II

Table of Contents

Introduction ........................................... 1

References ................................ 10

Experimental Section .................................. 12

Materials ................................. 12

Measurement ............................... 13

Methods ................................... 14

References ................................ 2 0

Results and Discussion ................................ 21

Biphen .................................... 21

[Run (bpy) 2 (biphen)] (PF6 ) 2 and

References ................................ 42

Summary ............................................... 67

Appendix

III

List of Tables

Table 3-1 1H NMR Spectra Data of Ligands ............ 32

Table 3-2 UV-Vis Data of Ligands .................... 33

Table 3-3 UV-Vis Data of [Run (bpy) 2 (biphen)] (PF6 ) 2

in CH3CN .................................. 35

Table 3-4 UV-Vis Data of

[ (bpy) 2RUII (biphen) RuII (bpy) 21 (PF5) 4

in CH3CN .................................. 36

Table 3-5 UV-Vis Data of Analogous

Ru Complexes .............................. 3 7

Table 3-6 UV-Vis Data of Mono- and Bi-metallic

Complexes ................................. 3 8

Table 3-7 Cyclic Voltammetry Data of Ruthenium

Complexes ................................. 39

Table 3-8 Oxidation Potentials of Ruthenium

Complexes ................................. 40

IV

List of Tables

Table 3-9 Redox Properties of Analogous

Ruthenium Complexes ....................... 41

v

List of Figures

Figure 2-1 The 1 H-NMR Spectrum of

5-N02-l,10-phenanthroline ................ 43

Figure 2-2 The 1H-NMR Spectrum of crude

5,6-diamino-1,10-phenanthroline .......... 44

Figure 3-1 The Structure and Numbering of

1,10-phenanthroline ...................... 45

Figure 3-2 The Structure and Numbering of

1,10-phenanthroline-5,6-dione ............ 46

Figure 3-3 The Structure and Numbering of biphen .... 47

Figure 3-4 The Structure of Pptd .................... 48

Figure 3-5 The Structure of

Dipyro[3,2-a;2',3'-c]phenazine ........... 49

VI

List of Figures


2,3-bis(2-pyridyl)-pyrazine .............. 50


2,5-bis(2-pyridyl)-pyrazine .............. 51

Figure 3-8 The 1H-NMR Spectrum of

1,10-phenanthroline in CDC1 3 ••••••••••••• 52


1,10-phenanthroline-5,6-dione in CDC1 3 ••• 53

Figure 3-10 The 1H-NMR Spectrum of biphen in CDC13 .. 54

Figure 3-11 The UV-Vis Spectrum of biphen in CHC1 3 •• 55

Figure 3-12 The UV-Vis Spectrum of biphen in CH3CN .. 56

VII

List of Figures

Figure 3-13 The UV-Vis Spectrum of 2,2-bipyridine

in CH3CN ................................. 57

Figure 3-14 The UV-Vis Spectrum of phenazine in

CH3CN .................................... 5 8


[Ru II (bpy) 2 (biphen) ] (PF 6) 2 ••••••••••••••••• 59



[Run (bpy) 2 (biphen) ] (PF 6 ) 2 in CD3CN ........ 61

VIII

List of Figures


in CD3CN ................................. 62

Figure 3-19 The UV-Vis Spectrum of

[RuII (bpy) 2 (biphen)] (PF6) 2 in CH3CN ........ 63

Figure 3-20 The UV-Vis Spectrum of

in CH3CN ................................. 64

Figure 3-21 The Cyclic Voltammogram of

[RuII (bpy) 2 (biphen)] (PF6) 2 ••••••••••••••••• 65

Figure 3-22 The Cyclic Voltammogram

[ (bpy2 ) Run (biphen) Run (bpy) 2 ] (PF6) ......... 66

IX

List of Figures

Figure A-1 The UV-Vis Spectrum of

5,6-diamino-1,10-phenanthroline ......... A-I

Figure A-2 The IR Spectrum of

5,6-diamino-1,10-phenanthroline ........ A-II

Figure A-3 The 1 H-NMR Spectrum of

5,6-diamino-1,10-phenanthroline ....... A-III

x

:Introduction

Electron transfer (ET) reactions are very common in

inorganic, organic and biological systems. Attempts to study

the fundamental chemistry of ET reactions have involved

simplified model systems. In particular, much research has

been devoted to the design and synthesis of molecular systems

comprised of electron donors and acceptors that mimic the

charge separation function of proteins involved in

photosynthesis.

In the past 30 years, long range ET between donor (D) and

acceptor (A) molecules has been studied in several systems in

which D and A are held apart by rigid spacer groups. The

rigid spacer groups are usually structures normally thought of

as good "molecular wires" such as aromatic and/or conjugated

systems1 • However, a variety of compounds can serve the same

function (rigid or semi-rigid spacer) such as proteins2 ,

steroids3 , and other saturated framework structures. In fact,

despite initial perceptions Pasmen et al. 4 have suggested that

through-bond interaction between the electron donor (D) and

the electron acceptor (A) separated by bridge a-bonds can

still lead to strong charge-transfer.

An electron donor and acceptor separated by a rigid

spacer ( --- ) can be depicted as in Scheme 1.

1

A --------- D

Scheme 1

If both A and D are metal centers the system in Scheme 1 could

be depicted as in Scheme 2.

M1 --------- M2

Scheme 2

Here, M1 and M2 may or may not be identical. If in fact M 1 and

M2 are the same metal center differing by one unit in

oxidation state (e.g. M1 = Mrr and M 2 = M rrr ) , a "mixed-valence"

system results (Scheme 3).

MII -------- MIII

Scheme 3

In this case, the conversion of the system in Scheme 3 to its

"redox-isomer" can occur by an ET mechanism (Scheme 4).

--- MII

Scheme 4

2

According to Robin and Day5 , intramolecular interactions

in mixed-valence systems like that shown in Scheme 3 can be

divided into three different types or classes. Class I

compounds refer to the case where there is little or no

electronic interaction between the metal centers. [The

perturbation Hamiltonian Hab coupling the initial (Mn --- Mrn)

and the final (Mrrr --- Mr states is equal to zero]. In

Class I compounds, the two metal centers act as independent

units. Class II compounds refer to an intermediate case (weak

to moderate interaction) . In class III compounds there is

very strong interaction and consequent delocalization of

charge over the entire supramolecule. In class III, the

individual characteristics of each metal are non-existent (the

transferring electron is considered to be delocalized) .

Strictly speaking, according to Fermi's golden rule (Eq.

1-1) 6 , the rate constant for the ET process shown in Fig. 1-4

(electron-exchange) can be determined:

kET = 2rr/h Hab2 FCWD (Eq. 1-1)

Here Hab is the electron coupling matrix element and FCWD is

the Franck-Condon weighted density of states.

As can be observed from Eq. 1-1, the magnitude of Hab is

directly proportional to kET and thus is a good measure of the

amount of electronic communication between Mn and Mrrr .

3

Hush7 has derived a relationship between Hab for the ET process

depicted in Scheme 4 and the energy and intensity of the

optical transition shown in Scheme 5

Scheme 5

Here, E0 P is the energy of what is referred to as an

intervalence charge transfer (IVCT) or a metal-to-metal

charger transfer (MMCT) band * vibrationally excited

state). For many mixed-valence systems, the MMCT band can be

observed in the red to near-IR portion of the spectra.) The

relationship between Hab and Et,P derived by Hush is shown in

Eq. 1-2.

(Eq. 1-2)

Solving eq.1-2 for Hab giving

0 ( E · /\v ) = 2 3 8 0 r 2 H 2 "'max op Ll 1/2 ab

4

Here, E0 P and E'1nax are the energy (cm-1 ) and molar extinction

coefficient (M-1 cm1 ) of the MMCT band, respectively. The

metal-metal distance (A) is depicted by r, and Llu112 (cm-1 ) is

the bandwidth at half-height. According to Hush Llu112 is

related to E0 P and to the internal energy difference between

the two redox isomers (LlE) .

Llu112 = 2310 (E0 P - LlE) (Eq. 1-3)

An intense (large e) MMCT band is indicative of significant

communication between the metal centers. Class I compounds do

not have any stability in the mixed valence form and hence

show no IVCT bands. Class II compounds show relatively weak

bands with larger bandwidth (e < 5000 M-1 cm-1 ; Llu112 > 2000 cm-

1) • Class III compounds show intense IVCT bands that are

fairly narrow (e > 5000 M-1 cm-1 ; Llu112 < 2000 cm-1 ).

Electrochemical data can also be used in a qualitative

way to either rule out the existence of any significant

electronic interaction in systems like that shown in Scheme 3

or infer (but not prove) the existence of such interaction.

The stability of the mixed-valence species shown in Scheme 3

can be described by measuring the comproportionation constant,

Kc, for its formation.

5

MII --- MII + MIII --- MIII ----+ 2 MII --- MIII

If the Mn --- Mn mixed-valence form has no special

stability, Kc = 4 (statistical limit). However, if Kc > 4, the

mixed-valence state shows some extra stability compared to the

Mn - - - Mn and Mnr MIII precursors.

This could be due to a number of factors. 8

1. Entropic factor (greater disorder possible in

mixed-valence form.)

2. Electrostatic effects (depend on molecular shape,

structure and solvent)

3. Synergistic factors (Mn stabilized by Mnr , etc.)

4. Electron delocalization

Since electron delocalization is only one factor determining

the size of Kc, the possibility of its existence is only

inferred if Kc > 4. If Kc = 4, however, then any significant

electron delocalization in the mixed valence form can be ruled

out.

It has been shown9 that when the difference in standard

reduction (Mn1 /Mn) potentials between the two ends of the

Mn --- Mn complex is sufficiently large (> 250 mV), a value

of Kc can be calculated from the electrochemical data.

6

(Eq. 1-5)

E1 ------- MIII --- MII

E2 ------- MII - - - MII

Qualitatively, then, the difference in reduction

potentials t.E1 , 2 ( = E1 - E 2 ) can be used to either rule out the

existence of electronic interaction or infer the possibility

of its presence. In this thesis, cyclic voltammetry (and

half-wave potentials, E112 ), will be used to observe whether or

not the reduction (or oxidation) of one end of a bimetallic

compound can affect the ease of the reduction (or oxidation)

of the other end.

Ruthenium(II) polypyridine complexes {ie. [Ru(bpy) 3 ] 2+;

bpy = 2,2'-bipyridine and derivatives) have been extensively

used for the elucidation of the factors that govern the rates

of ET reaction. 10 This class of compounds has many

advantageous properties:

1) Ru(II) polypyridine compounds can be used as light

absorption sensitizers in excited state and

photochemical reactions.

2) These complexes can be used as catalysts in

important processes such as the reduction of C02 •

3) Ru(II) polypyridine complexes tend to be stable in

7

both the oxidized and reduced forms. ([Ru (bpy) 3 ] 2+

can be stored in aqueous solutions for months 11 and

is unaffected by boiling cone. HCl or 50% aqueous

sodium hydroxide solutions12 .)

4) Ru(II) polypyridine complexes are well suited for

the study of the relationship between

electrochemical and spectroscopic properties.

In addition a large number of such complexes can be

synthesized with varying electrochemical and spectroscopic

properties.

Recently, a large number of bimetallic Run complexes

(Rurr-Rurr) have been studied where the rigid bridging group is

a bidentate polypyridine ligand. As is typical for

polypyridine ligands, these bridging ligands possess both o

donor and rr-acceptor properties. A number of such compounds

have been synthesized. Dose and Wilson13 reported the

preparation and properties of [Ru (bpy) 2 (bpm)] 2 + and

{[Ru (bpy) 2 ] 2bpm} 4 + (bpm = 2, 2 '-bipyrimidine and bpy =

bipyridine) . Gafney and co-workers14 reported the preparation

of monometallic and bimetallic ruthenium complexes based on

the ligand 2,3-bis(2-pyridyl) pyrazine (bpp). See Fig. 1-1

for structure diagrams of the bridging ligands bpm and bpp.

In this work the preparation and properties of the

monometallic and bimetallic Run complexes of a new bidentate

polypyridine bridging ligand tetrapyridophenazine (biphen) are

8

described. The structure of biphen is shown in Fig. 1-1. The

complexes were characterized by UV-Vis and NMR spectroscopy.

In addition, cyclic voltammetry was used to measure whether or

not the possibility of electron communication between the

ruthenium centers (across biphen) existed. Finally, the

results will be compared to other similar systems.

9

Reference

1. (a) Guarr, T.; McGuire, M. E.; McLendon, G. J. J. Am.

Chem. Soc. 1985, 107, 5104-5111.

(b) Kira, A. and Imanura, M. J Phy. Chem. 1984, 88,

1865-1871.

(c) Miller, J. R.; Beitz, J. V.; Huddleston, R. K . .iI.....

Am. Chem. Soc. 1984, 106. 5057-5068.

2. McLendon, G. Acc. Chem. Res. 1988, 21, 160-167.

3. Closs, G. L.; Calcaterra, L. T.; Green, N. J. Penfield,

K. W.; Miller, J. R. J. Phy. Chem. 1986, ..2...Q, 3673-3683.

4. Pasman, P. Verhoeven, J. W.; Boer, Th. J. de

Tetrahedron Lett. 1977, 207-210.

5. Robin, M. B.; Day. P. Adv. Inorg. Chem. Radiochem.

1967, 1...Q_,__ 247.

6. Yonemoto, E. H.; Saupe, G. b.; Schmehl, R.H.; Hubig,S.

7 .

M.; Riley, R. L.; Iverson, B. L.; Mallouk T. E. J. Am.

Chem. Soc. 1994, ~ 4786-4795.

a. Allen, G. C.; Hush, N. S. Prog. Inorg. Chem. 1967,

..a..,_ 357.

b. Hush, N. S. Prog. Inorg. Chem. 1967, ..8._,_ 391.

c. Hush, N. S. Electrochimical Acta. 1968, .lJ...,__ 1005-

1023.

8. Creutz, C. In Prog. Inorg. Chem.; Lippard, S. J.; Ed.;

John Wiley & Sons: New York, 1983; pp 1-73.

10

9. Richardson D. E.; Taube H. Inorg. Chem. 1981, 20, 1278-

1285.

10. Kavarnos, G. J.; Turro, N. J. Chem. Rev. 1986, ~ 481-

490.

11. Brandt, W.W.; Smith, G. S. Anal. Chem. 1949, ~ 1313-

1319.

12. Burstall, F. H. J. Chem. Soc. 1936, 173-175.

13. Dose, E. V.; Wilson, L. Inorg. Chem. 1978, .11..i._ 2660-

2666.

14. Fuchs, Y.; Lofters, S; Dieter, T.; Shi, W.; Morgan, R.;

Strekas, T. C.; Gafney, H. D.; Baker, A.D. J. Am. Chem.

SQQ..._ 1987, ~ 2691-2697.

11

Experimental Section

Materials. l, 10-Phenanthroline (phen, 99+%), hydroxylamine

hydrochloride (NH20H·HC1, 99%), ammonium hexafluorophosphate

99.9%), acetonitrile 3 (CH CN, 99%) and sodium

hydrosulfite (Na2 S20 4 , 85%) were purchased from Aldrich

Chemical Co. and used without further purification. Fuming

sulfuric acid (H2S04 , 30% S03 ), cone. nitric acid (HN03 , 69-71

%) and glacial acetic acid (CH3COOH, 99.7%) were all reagent

grade and purchased from Fisher Chemical Co. and used as

received. The solvent ethylene glycol (HOCH2CH20H) was

purchased from Eastman Kodak Company. Dichloromethane (CH2Cl2 ,

99. 5%), ethanol (C2H50H, 95%), methanol (CJi OH), chloroform

(CHC1 3 ) and potassium hydroxide (KOH, 85+%) were purchased

from E.M. Science and used as received. Absolute ethanol

(C2H50H) was purchased from Midwest Grain Products and used as

received. The deuterated solvents chloroform (CDC1 3 , 99.8

atom% D), acetonitrile (CD3CN, 99. 8 atom% D), and methyl

sulfoxide ((CD3 ) 2SO, 99.9 atom% D) were purchased from

Cambridge Isotope Laboratories and used as received.

Polarographic grade tetrabutylammonium hexaf luorophosphate

(TBAH) was purchased from Bioanalytical Systems Inc. Chemicals

and used as received. Acetonitrile used for UV-Vis spectra

was spectrophotometric grade and was purchased from E. M.

Science. All water used for reactions was purified from a

12

Millipore "Milli-Q" water system. Acetoni trile used for

electrochemical experiments was stored over 4 A "Molecular

Sieves" purchased from MCB Manufacturing Chemists or from

Aldrich Chemical Co. Some electrochemical experiments used

acetonitrile (E.M. Science, HPLC grade) that had been

distilled over CaH2 (Aldrich Chemical Co. , 95+%) and then

stored over 4 A Sieves (activated at 350 °C for 24 h.)

Measurements. Melting point measurements were performed on a

Laboratory Devices MEL-TEMP. 1H NMR spectra were recorded

using a General Electric QE-300 FT-NMR. UV-Vis spectra were

recorded on either a Shimadzu UV-160U or a Shimadzu UV-3100

recording spectrophotometer. IR was obtained on a Nicolet 20

DXB FT-IR spectrometer. Electrochemical measurements were made

using either a Ag wire or a saturated sodium chloride calomel

electrode (SSCE, Bioanalytical System, Inc.) as a reference

(room temperature). A 1.5 mm platinum button electrode was

used as the working electrode and a platinum wire was used as

the auxiliary electrode. The electrolyte was

tetrabutylammonium hexaf luorophosphate (TBAH) . Cyclic

voltammetry measurements were obtained using an EG&G PAR Model

173 potentiostat for potential control with a Model 175

universal programmer as a sweep generator. Voltammograms were

recorded on a The Recorder Company Model 200 xy-recorder. The

E112 values from the cyclic voltammograms were calculated from

13

the average of the Ev {potential at current maximum) values

for the anodic and cathodic waves. Elemental analyses were

performed by Atlantic Microlabs, Norcross, GA.

Methods.

1,10-phenanthroline-S,6-dione (phendione) and 5-nitro-1,10-

phenanthroline (5-N02-phen): These compounds were synthesized

by using a method analogous to that reported by Amouyl et.

al 1 • In a typical preparation, 1,10-phenanthroline (9.1133 g,

0.0505 moles) and fuming H2 S04 (55 mL) were mixed in a three

neck RB flask. The mixture was heated to 110 °C and cone. HN03

(10 mL) was added drop by drop (using a separatory funnel) to

the oleum/phenanthroline solution. The reaction mixture was

heated to 145 °C and cone. HN03 (29 mL) was added over 0.5 h.

At the end of this addition the temperature had dropped to 120

°C. Then the yellow reaction mixture was cooled to room

temperature and left stirring for 2 h. The reaction mixture

was then poured into 100 mL of ice and neutralized with 30%

NaOH to around pH 3 to 5. The yellow precipitate was removed

by filtration using a 150 mL M frit. The solid in the frit

was thoroughly washed with water. The filtrate and water

washes were saved and set aside. The solid (mostly 5-N02 -

phen) was dried in vacuo.

g (57.64%, based on phen).

Yield of crude 5-N02 -phen: 6.1263

The dried solid was triturated with 100 mL of water (to

14

remove any remaining phendione) , and the resulting suspension

was filtered. The filtrate was saved and set aside. The

solid was suspended in 35 mL of hot ethanol (95%), and the hot

solution was filtered using a 30 mL M frit. The filtrate was

cooled slowly to room temperature and precipitate formed. The

mixture was filtered using a 60 mL F frit. The solid obtained

was dried in vacuo. Yield of pure 5-N02 -phen: 3.3505 g (32%,

based on phen) m.p. 198-200 °C (lit2 m.p 202-204 °C). 1 H NMR

(CDC1 3 , Fig. 2-1), ppm (TMS): 7.60 (dd, lH), 7.83 (dd, lH),

8.46 (d, lH), 8.71 (s, lH), 9.12 (d, lH), 9.32 (d, lH), 9.36

(d, lH) .

The filtrate (water washes) from the trituration, and the

filtrate and water washes from the 5-N02 -phen synthesis were

combined and extracted with CH2Cl2 (in two batches) in a 500

mL separatory funnel.

with 50 mL of CH2Cl 2 •

Each batch was extracted four times

The combined ~H ~l extracts were

evaporated overnight in the hood. Yield of crude phendione

(2.5510 g, 23.99 %, based on phen). m.p. 242-248 °C.

Methanol (120 mL) was heated in a 200 mL RB flask

equipped with a stir bar and a reflux column. The crude

phendione from the previous step was then added quickly. The

yellow solution was boiled about 5 min until the solid almost

all dissolved. The hot solution was filtered through a warm

150 mL M frit. The filtrate was cooled to room temperature

and crystals formed. The mixture was filtered using a 60 mL

15

F frit and the solid was washed with 15 mL of cool CH30H. The

bright yellow solid was dried in vacuo. Yield of pure

phendione: 1.2791 g (10.6% based on phen) m.p 252-254 °C. (lit

3 m.p. 258 °C). 1H NMR (CDCL3) I ppm (TMS): 7. 60 (m, 2H) I 8. 52

(dd, 2H) I 9.13 (dd, 2H).

5,6-diamino-1,10-phenanthroline (diamino-phen): The procedure

of Pesin4 and coworkers (for the preparation of 4,5-

diaminobenzo-2,1,3-thiadiazole) was followed with slight

modification. In a typical preparation, a solution of

potassium hydroxide (4.0163 g, 71.6 mmol) in 13 mL of absolute

ethanol was gradually added to a stirring mixture of 5-N02 -

phen (1.0063 g, 4.47 mmol), hydroxylamine hydrochloride

(2.0016 g, 28.8 mmol) and 13 mL of ethanol. The mixture was

stirred for 1 h, and then 53 mL of water was added. After

heating to 70 °C, sodium hydrosulfite (8.0376 g, 46.16 mmol)

was added. The mixture was heated to boiling and then cooled

to room temperature, resulting in a yellow suspension. The

product was collected on a fine glass frit, washed with a

small amount of cool water and dried in vacuo. Yield: 1.0313

g (109%, based on 5-N02-phen). This crude product (1H-NMR in

Fig.2-2) was used in the preparation of biphen. ( A small

amount of analytically pure diamino-phen was isolated from

these preparations. Appendix I contains details about the

procedure and analysis.)

16

Biphen (C12 H24 N6 ) : This ligand was prepared by condensation

of the crude diamino-phen with phendione. In a typical

preparation, diamino-phen (0.1090 g, 0.52 mmol) was reacted

for 20 minutes with phendione (0.0813 g, 0.387 mmol) in 20 mL

of hot glacial acetic acid. The mixture was allowed to cool

to room temperature. An orange-brown solid was collected on

a fine glass frit and washed with 2 mL of glacial acetic acid

and then dried in vacuo. Yield. 0.1113 g (74.95% based on

phendi one) .

The crude sample was then stirred with 50 mL of

chloroform for 1 h and then filtered through a fine glass frit

to remove insoluble materials. The filtrate was then allowed

to evaporate to dryness in the hood. Yield: 0.336 g (22.63%

based on phendione). m.p. > 380 °C. 1H NMR (CDCL1 , 300 MHz),

ppm (TMS) : 7. 85 (dd, 4H), 9. 34 (dd, 4H), 9. 66 (dd, 4H) . Anal.

Calcd for C12H 2!J 6: C 74.99%, H 3.15%, N 21.86%.

74.57%, H 3.61%, N 21.66%.

. . (0.1056 g, 0.203 rnrrrol)

Found C

and biphen

(0.0380 g, 0.0989 mmol) were refluxed in 30 mL of ethylene

glycol for 3 h. The mixture was cooled to room temperature

and 3 0 mL of H20 was added. The insoluble solids were

filtered out through a fine glass frit and 0.4690 g of NH4PF6

was added and the product precipitated very fine red crystals.

17

The product was collected on a 15 mL F frit, washed with a

small amount of cold water and dried in vacuo. Yield: 0.1912

g (107.93%, based on biphen).

The crude product was purified by using a two-step

procedure. First, it was dissolved in 9 mL of acetone and

filtered using a 2 mL F frit. Chloroform (15 mL) was added to

the filtrate resulting in the precipitation of solid. The

mixture was filtered, and the solid washed with 1 mL of

chloroform and 1 mL of ether and then air-dried overnight.

The dried solid was suspended in 15 mL of hot water (@ 70 °C)

and then acetonitrile was added dropwise to this solution

until the solid just dissolved. The solution was cooled to

room temperature slowly and orange-red solid was formed. The

solution mixture was filtered and the solid collected and

dried in vacuo. Yield: 0.0928 g (52.40% based on biphen).

Anal. Calcd for [bpy) 2Rurr(biphen)Rurr(bpy) 2 ] (PF6 ) 4 : C 42.92% H

2.48% N 10.95%. Found C 43.01%, H 2.52%, N 10.87%. 1H NMR

(CD3CN, 300 MHz), ppm (TMS): 9.6 (d, 4H), 8.55 (m, 8H), 8.29

(d, 4H), 8.14 (m, 4H), 8.02 (m, 8H), 7.86 (d, 4H), 7.74 (d,

4H) , 7. 4 7 (m, 4H) , 7. 26 (m, 4H) .

[RuII (bpy) 2 (biphen](PF6 ) 2 : Biphen (0.1235 g, 0.321 mmol)

and 130 mL of ethylene glycol were heated in a 200 mL 3-neck

RB flask for 1 h. A solution of cis-Rurr (bpy) 2c12 ·2H20 (0. 0513

g, 0.0985 mmol ) in 2 mL of ethylene glycol was added dropwise

18

over 1. 5 h. The mixture was heated at reflux for 2 h (The

orange color turned eventually to an orange-red.) . The

mixture was then cooled to room temperature, 130 mL of H20 was

added, and this mixture was filtered using a 30 mL F frit.

Addition of NH4PF6 • (0.1046 g) to the filtrate produced a solid

consisting of very fine red crystals. The suspension was left

covered overnight and then filtered using a 60 mL M frit. The

solid collected was washed with 20 mL of H20 and 5 mL of ethyl

ether and dried in vacuo. Yield: 0.0558 g (52.08% based on

Run (bpy) 2Cl2·2H20) ·

The crude product was purified using a solution of

ethanol:water (1:1). The ethanol/water solution (50 mL) was

heated in a 100 mL RB flask equipped with a stir bar and a

reflux column. After adding the crude product, the mixture was

boiled about 5 min until the solid almost all dissolved. The

hot mixture was filtered using a warm 15 mL F frit. The

filtrate was slowly cooled to room temperature resulting in

precipitation of an orange-red solid. The solid was collected

and dried in vacuo. Yield: 0.0200 g (18.66%, based on

Rurr(bpy) 2Cl2·2H20). 1H NMR (CD 3CN, 300 MHz), ppm (TMS): 9.48 (d,

2H), 9.24 (d, 2H), 8.60 (d, 2H), 8.57 (d, 2H), 8.32 (s, 2H),

8.27 (d, 2H), 8.20 (d, 2H), 8.16 (d, 2H), 8.05 (m, 2H), 7.93

(d, 2H), 7.84(dd, 2H), 7.72 (dd, 2H) 7.53 (m, 2H), 7.37 (m,

2H). Anal. Calcd for [Rurr(bpy) 2(biphen)] (PF6 ) 2: C: 48.58%, H:

2.59%, N: 12.88%. Found: C: 48.97%, H:3.09%, N: 12.07%.

19

Reference

1. Amouyl, E.; Homsi, A. J. Chem. Soc. Dalton Trans.

1990, 1841-45.

2. Aldrich Catalog Hand.book of Fine Chemicals Aldrich

Chemical Company, Inc.; 1992-1993; pp.929.

3. Smith, G.F.; Cagle, F.W. J. Org. Chem. 1947, 12, 781.

4. Pesin, V. G.; Sergeev, V. A.; Nikulina, M. G. Chem.

Heterocylic Compounds 1968, ~' 186-188.

5. cis-Rurr(bpy) 2Cl2 was previously prepared & purified by

Greg Juriga using the following procedures: (a)

Sullivan, B. P.; Salmon, D. J.; Meyer, T. J. Inorg.

Chem. 1978, 17, 3334. (b) Sprintschnik, G.;

Sprintschnik, H. W.; Kirsch, P. P.; Whitten, D. G. i.L..

Am. Chem. Soc. 1977, .2.2, 4947.

20

Results and Discussion

Biphen: This is a condensation product of crude diamino-phen

and phendione and is a light yellow solid. The structures and

numbering schemes for phenanthroline, phendione and biphen are

given in Fig. 3-1 to Fig. 3-3. The actual 1H-NMR spectra for

these three ligands are shown in Fig. 3-8 to Fig. 3-10,

respectively, and their NMR spectral data listed in Table 3-1.

In the 1H-NMR spectrum of biphen (Fig. 3-10), there are three

sets of peaks with the area ratio 1:1:1. This peak pattern

(two sets of doublets of doublets and one quartet) appear to

be typical for 1,10-phenanthroline symmetrically substituted

at positions 5 and 6.

(Fig. 3-9) shows the

For example, the 1H~NMR of phendione

same peak pat tern. Moreover, 1, 10-

phenanthroline itself (Fig. 3-8) shows the same pattern except

for the singlet at 7. 78 ppm which is assigned to the two

equivalent hydrogens at positions 5 and 6. The 1H-NMR for

biphen (Fig. 3-10) is therefore consistent with a structure

having two equivalent phenanthrolines fused (at positions 5

and 6) through a structure containing no hydrogens (in this

case pyrazine) .

The peak assignments and chemical shift values list in

Table 3-1 reveal that the biphen ligand appears to be fairly

electron deficient when compared to either phendione or phen.

Evidence for this comes from the fact that all three sets of

peaks for biphen are shifted downf ield from those of the other

21

two ligands. The most dramatic shift occurs for the peaks

assigned to H4 , 7 , these protons being the closest to the

pyrazine bridge.

The UV-Vis spectrum of biphen in CHC1 3 is shown in Fig.

3-11. There are two main areas of absorption. The first is

between 250 nm and 300 nm and the second is in the range 350

nm to 400 nm. It is the second set (lower energy) peaks which

give biphen its characteristic light yellow color. The peak

maxima and absorption coefficients for biphen in CHC1 3 are

listed in Table 3-2. It should be noted that CHC1 3 was the

only solvent found in which biphen had a high enough

solubility to allow accurate determinations of absorption

coefficients. The UV-Vis spectrum of biphen was also taken

using CH3CN as the solvent (Fig. 3-12; Table 3-2).

The UV-Vis spectra of 2,2'-bipyridine (bpy) and phenazine

(both in CH3CN) are shown in Fig. 3-13 and 3-14, respectively.

In addition, peak maxima for both spectra are summarized in

Table 3-2. Not surprisingly, the UV-Vis spectrum of biphen is

roughly equivalent to the sum of the spectra of bpy and

phenazine (the two structural components of biphen) . It

should be noted that although both phenazine and biphen are

yellow in color (and show lower energy absorptions), the low

energy maximum for biphen is red-shifted about 25 nm as

compared to phenazine. This may simply reflect the effect of

the larger ring system in biphen.

22

The monometallic and bimetallic Ru complexes are both

orange-red solids whose structures are shown in Fig. 3-15 and

Fig. 3-16. The actual 1H-NMR spectra in CD3CN are shown in

Fig. 3-17 and Fig. 3-18, respectively. The spectrum of the

monometallic complex [Run(bpy) 2 (biphen)] (PF6 ) 2 (Fig. 3-17) can

be integrated to 28 hydrogens, the expected number for two bpy

ligands (2 x 8H) and one biphen (1 x 12H) . The spectrum of

the bimetallic complex [ (bpy) 2Run (biphen) Run (bpy) 2 ] (PF6 ) 4 (Fig.

3-18) can be integrated to 44 hydrogens: four bpy ligands (4

x 8H) and one biphen (1 x 12H). A comparison of the 1H-NMR

spectra of the monometallic and bimetallic complexes reveals

striking differences at chemical shift values greater than 9

ppm. The monometallic complex shows two doublets between 9.1

and 9.6 ppm, representing 4 H, while the bimetalllic complex

show one doublet, also representing 4 H, at close to 10 ppm.

These are expected differences for the H2 , 9 and H2 ., 9 • positions

(Fig. 3-3) of the bridging biphen ligand. For the

monometallic complex, these two positions would not be

equivalent, since -Ru (bpy) /+ is bound to only end of the

biphen. In this case, it would be expected that the doublet

at -9. 5 ppm represents the H2 , 9 positions biphen near the point

of attachment of the -Ru (bpy) /+ fragment. On the other hand,

the bimetallic complex might be expected to show the H2 , 9 and

H2 ., 9 • position as equivalent, since a -Ru (bpy) /+ fragment is

23

bound at both ends of biphen, forming a symmetric species.

The downf ield shift for this doublet compared to either

doublet in the monometallic case most likely represents the

effects of a total 4+ charge from the two -Ru(bpy)/+

fragments.

As is typical for hexafluorophosphate salts of Ru (II)

polypyridyl complexes, both the monometallic and bimetallic

Ru(II) complexes of biphen were quite soluble in acetonitrile

and acetone and partially soluble in water. The UV-Vis

spectra of both complexes (Fig. 3-19, Fig. 3-20) were taken in

CH3CN, and the absorption bands that were observed are listed

in Tables 3-3 and 3-4 along with transition assignments. The

UV-Vis spectra of the monometallic and bimetallic complexes

both show very similar peak patterns. Each spectrum shows

three main areas of absorption. The first is between 240 nm

and 340 nm, the second from 340 nm to 400 nm and the third

from 400 nm to 500 nm. It is the third set (lower energy) of

peaks which give the complexes their characteristic red-orange

color.

The first absorption area (240 nm to 340 nm) is

characteristic of rr ~-> rr* transitions of the bpy and the

biphen ligands. This assignment is reasonable based on

comparisons with the spectra of free biphen and bpy (Fig. 3-12

and Fig. 3-13), and transition assignments from the

literature1. The ratio of the e values for the bimetallic and

monometallic complexes (eb/em) at 282 nm is 1.7:1. This is an

24

expected result (at least qualitatively), since the bimetallic

complex contains two additional bpy ligands.

The second absorption area (340 nm to 400 nm) is

characteristic of transitions of the biphen ligand (in the

phenazine portion) . This can be seen by comparing the spectra

in Fig. 3-19 and Fig. 3-20 with those of free biphen (Fig. 3-

12) and phenazine (Fig. 3-14). The ratio eb/em in this area

of the spectrum is only about 1.2:1. This is an expected

result, since both complexes contain only one biphen ligand

each.

The third absorption area (400 nm to 500 nm) is

characteristic of overlapping MLCT bands from Ru(drr) ~->

biphen(rr*) and Ru(drr) ~-> bpy(rr*) transitions. The ratio of

eb/em is approximately 2.2:1. Once again, this is an expected

result, based on the ratio of the number of Run centers in

the two complexes.

The energies of the MLCT bands of both the mono- and

bimetallic complexes give some information about the

electronic structure of the bridge ligand biphen and some

indication of the extent of metal-metal interaction in the

bimetallic case. The expected energy of the MLCT bands can be

calculated from the absolute value of the measured energy

difference between the oxidation potential of Run and the

reduction potentials of either biphen or bpy.

25

EMLcT ( eV) = E (RuIIr /II ) - E (biphen°11-) (Eq. 3-1)

EMLCT ( eV) = E (RuIIr /II ) - E (bpyDll-) (Eq. 3-2)

Using Eq. 3-1 (and cyclic voltammetry data from Table 3-7

(vide infra)) and converting the resulting energy units to nm

for both the monometallic and bimetallic complexes results in

a predicted .A.MLcT = 582 nm. This lower energy .A.MLcT value

is not observed experimentally for either complex. Doing the

same calculation for bpy in Eq. 3-2. the A. values result in

predicted A. = 454 nm for both complexes. The .A.MLcT values

observed experimentally seem to correspond to these higher

energy RuII to bpy MLCT transitions. Thus, it appears that

the molecular orbitals in biphen that are reduced

electrochemically (most likely centered in the phenazine

portion) are electronically isolated from those that are

reduced photochemically (bpy portion) . These observations are

consistent with behavior reported in the literature for other

similar ligands, such as pptd2 , and dppz3 (Fig. 3-4 and Fig.

3-5) .

The experimentally observed .A.MLcT values for the

monometallic and bimetallic complexes reported here are nearly

identical. This implies that the metal-metal interaction in

the bimetallic complex is negligible. For example, it would

be expected that addition of the second Ru II center in the

bimetallic species would make the phenazine portion of biphen

26

easier to reduce, thus lowering the energy of the MLCT band in

the complex. Since this is not observed, it appears that both

ends of the bimetallic complex act as independent

(bpy)Ru(bpy)/+ units.

Table 3-6 lists .\nax values for both Run complexes

and bimetallic reported here and values for other mono-

systems. As can be seen from the data, red shifts in .A.MLcT

values (20-80 nm) usually accompany formation of bimetallic

complexes from their monometallic precursors. This is usually

taken as evidence for at least a small amount of metal-metal

interaction. These red-shifts are not observed for the

bimetallic Run biphen complex reported here. The results of

cyclic voltammetry experiments on monometallic and bimetallic

complexes in acetonitrile with 0 .1 M TBAH as supporting

electrolyte are listed in Table 3-7. E112 values were

calculated from the average of the anodic and cathodic peak

potentials [E112 = (~a+Epc) /2] at a scan rate of 100 mV · s-1 •

Reduction of [Rurr(bpy) 2 (biphen)] (PF6 ) 2 results in three

waves: -1.26 V, -1.78 V and -1.99 V (vs Fe/Fe+; Ag wire ref.,

Fig 3-21 b) . The first wave is assigned to the reduction of

biphen and appears to be complicated by adsorption in the

cathodic scan. The peaks at -1.78 and -1.99 (barely visible)

are assigned as reductions of the bipyridine ligands. These

processes to do not appear to be reversible.

Reduction of [ (bpy) 2 Run (biphen) Run (bpy}i ] ( PF6 )4

results in two waves : -1.21 V and -1.78 V (vs. Fe/Fe+; Ag

27

wire ref., Fig. 3-22 b) . The first wave most likely

corresponds to the reduction of biphen and the second wave

corresponds to the reduction of bipyridine ligands. The wave

assigned as bipyridine reduction is larger and this is most

likely due to the fact that two 1 e- reductions are occuring

simultaneously. One bpy- being produced at each end of the

bimetallic complex. The E112 values of biphen in the

monometallic and bimetallic complexes are nearly identical.

This information, along with the apparent single reduction

wave for bipyridines at either end of the bimetallic complex,

implies that "end-to end" electron communication in

bimetallic species is very small. The asssignment of

the

both

the biphen and bpy reduction waves here compares well with

reduction waves assigned in the literature3 to bpy and dppz (a

monodentate analog of biphen) in the complexes [Rurr (bpy) 3 ] 2+

and [Rurr (bpy) 2 ( dppz) ] 2+. It should be notedbiphen is more

easily reduced than bypyridine by ca. 0.5 V, due to the lower

energy rr* orbital of the biphen moiety.

Oxidation of the monometallic complex results in one wave

at +0.97 V (vs. Fe/Fe+; Ag wire ref., Fig. 3-21a). This is

assigned as arising from a le- oxidation of the metal center

(Rurr --> Rtlrr ) . The peak height for a 1 mM solution of

complex corresponds to a current of approximately 1. 8 µA.

Oxidation of the bimetallic complex results in one wave at

+0.93 V (vs. Fe/Fe+; Ag wire ref., Fig. 3-22a) This wave is

assigned as arising from a two electron oxidation of the metal

28

centers (Run --> Run at each of two sites). The peak

height for a 1 mM solution of complex corresponds to a current

of 4.8 µA.

Comparison of the oxidation waves for the mono- and

bimetallic complexes reveals some interesting information.

First of all, the peak heights (in µA) show that, for equal

concentrations of complex, about twice as much current is

observed for the bimetallic complex. This is expected if both

Run sites are oxidized at the same or nearly the same

potential.

A second observation is that the E112 values for the

monometallic and bimetallic complexes are nearly identical.

This is somewhat surprising, since it might be expected that

a 4+ complex would be somewhat harder to oxidize than a 2+

complex.

A third observation involves the oxidation of the

bimetallic complex. As stated in the introduction, the mixed

valence form of this complex would be produced after the first

electron is removed (at potential E1 ) •

form was

[ (bpy) 2RUII-biphen-RuII (bpy) 2] 4+

If the mixed-valence

Ei ------>

-le-

[ (bpy) 2RUII-biphen-Ru1 II (bpy) 21 S+

29

very stable relative to the Run /Run or Runr /Runr form, it

would be expected that the second electron would be harder to

remove (at potential E2) .

E2 [ (bpy) 2RUII-biphen-RuIII (bpy) 2] S+ ~~~~~~~->

-le-

[ (bpy) 2RUIII_biphen-RuIII (bpy) 2] G+

In other words, if the comproportionation constant (Kc) were

large, E2 > E1 and two well-spaced le- waves would be observed

for the bimetallic complex. Since only one wave is observed,

E1 = E2 and Kc is not large. The two metal centers do not seem

to communicate very well.

Despite the above analysis, it should be noted that the

oxidation wave for the bimetallic complex shows a peak

separation (~EP) of about 80 mV. This is much larger than

expected for a 2e- process (30 mV) . Therefore, there is some

evidence for stabilization of the Run /Rurn mixed-valence

species, even though two well-resolved le- oxidation waves

were not obtained. The 2e- oxidation may consist of two

closely spaced le- oxidations. Therefore the value of Kc,

while small, is still most likely greater than 4. It is not

clear, from this analysis, however, whether any of the

stabilization of the Run /Rurn state is due to any

delocalization.

It should be noted that the oxidations of both the mono-

30

and bimetallic complexes were also carried out referenced to

an SSCE electrode. The E112 values obtained were +1. 23 V for

the monometallic complex, and +1.34 V for the bimetallic. In

actual fact, the monometallic complex probably has an E112 ~

1.33 V (identical to the bimetallic). This is because the

Fe/Fe+ couple in the monometallic CV appeared to be about 0.10

V too low (probably due to axis calibration error or some

problem with the reference electrode). For this reason, Table

3-9 lists the E112 (RurII III ) for the monometallic complex as

+1. 33 V vs. SSCE. The E112 (RuIIr III ) values for the mono

and bimetallic complexes seem reasonable when compared to

similar RuII complexes seem reasonable when compared to similar

RuII complexes (Table 3-9). Reductive scans were not taken for

the two complexes vs SSCE.

31

ligand

phen

phendione

biphen

Table 3-1

1H NMR Spectra Data of Ligandsa,b

9.20(d) 7.63(q)

9.13(dd) 7.60(q)

9.67(dd) 7.86(q)

8.24(dd) 7.78(s)

8. 52 (dd)

9. 35 (dd)

achemical shifts are given in ppm (vs TMS) in CDC1 3 •

bs, d, dd and q = singlet, doublet, doublet of doublets and

quartet, respectively.

32

Ligand

biphen

biphen

Table 3-2

UV-Vis Data of Ligands

Solvent ~ (run)

(e x 10-3 M-1 cm-1 )

CHC1 3 390.4 (29.2)

380.8 (14.9)

370.2 (16.4)

361. 5 (8.97)

351. 8 (7.18)

(sh) 335.0 (9.10)

(sh) 324.7 (14.1)

(sh) 308.9 (20.2)

276.8 (66.2)

CH3CN 389.0

379.8

368.8

360.7

350.8

274.5

33

Table 3-2 (Cont'd)

Ligand Solvent Aman (nm)

( e x 10-3 M-1 cm-1 )

bpy CH3CN 281. 5

236.5

phenazine CH3CN 362.8

(sh) 359.8

(sh) 357.9

(sh) 348.0

(sh) 324.2

248.0

208.0

34

(sh)

(sh)

Table 3-3

UV-Vis Data of [Ruu (bpy) 2 (biphen)] (PF6 ) 2 in CH3CN

Amax (nm)

(e x 10-3 M-1 cm-1 )

449.9 (14.0)

422.7 (12.5)

380.5 (24.4)

362.3 (17.3)

314.1 (36.1)

282.5 (86.4)

246.0 ( 51. 2)

Run

Transition

assignments

( dII) --> biphen (II*) MLCT

Run (dII) --> bpy ( rr*) MLCT

Run ( drr) --> biphen (II*) MLCT

Run (dII) --> bpy (II*) MLCT

ligand biphen II --> II*




ligand bpy II --> II*



35

Table 3-4

UV-Vis Data of [ (bpy)2RUII(biphen)RuII(bpy)2l (PF6)4 in CH3CN

Amax (nm)

( e x 10-3 M- 1 cm-1 )

442.0 (31.8)

(sh) 420.0 (27.6)

370.0 (29.6)

351. 3 (23.9)

(sh) 322.0 (40.1)

282.5 (146)

44.5 (58.2)

Rull

Transition

assignments

( dII) --> biphen (II*)

Rull ( dII) --> bpy (II*)

Rull ( dII) --> biphen (II*)

Rull ( dII) --> bpy (II*)








36

Table 3-5

UV-Vis Data of Analogous Ru Complexes

Compound

[Ru (bpy) 2 (dppz)] 2+c

[Ru (bpy) 2 (biphen) ] 2+

Amax (nm) a

(e x 10-3 M-1 cm-1 )

448(1.57), 366(1.55), 357(1.56)

352(sh), 342(sh), 315(sh),

284(9.36), 255(4.18) I 212(5.00)b

449.9(14.0), 422.7(sh), 380.5(24.4)

362.3(17.3), 314.1(36.1), 282.5(86.4)

246.0(51.2)

452 (1. 45) I 345 (sh) I 323 (sh) I

285(8.71), 250(2.51), 238(2.95),

208 (sh) I 185 (8 • 91)

aunless otherwise noted, the absorptions are taken in CH3CN.

bin EtOH.

cdppz=dipyrido[3,2-a;2',3'-c]phenazine ref.4

37

Table 3-6

UV-Vis Data of Mono- and Bimetallic Complexes

Complexes Amax (nm) color

[Ru (bpy) 2 (biphen) 12+a 450, 423 (sh) t 381, red-orange

362, 314(sh), 283, 246

{[Ru (bpy) 212 (biphen) }4+a 442, 420 (sh) t 370, red-orange

351, 322(sh), 283,

245

[ (bpy) 2Ru ( dpp) 12+b 436, 465, 475 dark-red

{ [ (bpy) 2Ru1 2 (dpp) }4+b 425, 436, 525 reddish-purple

[Ru (2, 3-dpp) (CO) 21 Cl2c 384 yellow

(µ-2,3-dpp) [Ru(C0)2Cl212c 409 red-brown

[Ru(2,5-dpp) (C0) 21Cl2c 405 red-brown

(µ-2, 5-dpp) [Ru (CO) 2Cl212c 448 yellow

[Ru (bpy) 2 (HAT) 12+a 207, 277, 432, 484 yellow

{[Ru (bpy) 212 (HAT) l 4+a 206, 243, 252(sh), aubergine

276, 405, 490, 572

{[Ru (bpy) 213 (HAT) 2}6+a 206(sh), 244, 251, deep blue

278, 364' 401, 525,

580

cin CH3CN. ref. 6 µ-2, 3-

dpp=2,3- (2-pyridyl)-pyrazine (Fig. 3-6), µ-2,5-dpp=2,5-bis(2-

pyridyl)-pyrazine (Fig. 3-7). ain H20. ref.7

HAT=hexatriphenylene

38

Table 3-7

Cyclic Voltanunetry Data of Ruthenium Complexesa

Complexb Solvent Ei12

.0.EP, mV)

[Run (bpy) 2 (biphen)] 2+c CH3CN/O .1 M TBAH +0.97 (60)

-1. 26

-1.78

-1. 99

[Run (bpy) 2 (biphen)] 2+a CH3CN/0 .1 M TBAH +0.40 (60)

+1.33 (55)

[ (bpy) 2Run (biphen) Run (bpy) 2] 4 +c CH3CN/0 .1 M TBAH +0.93 (65)

-1.21

-1.78

[ {bpy) 2RUn (biphen) Run (bpy) 2J 4 +d CH3CN/O .1 M TBAH +0.40 (65)

+1.34 (80)

aPotentials are in volts. Scan rate = 100 mV/s.

TBAH=tetrabutylammonium hexafluorophosphate. Values in

parentheses indicate peak separations (.0.EP = Eanodic- Ecathodic) in

mV. bAll complexes were PF 6 - salts. cPlatinum working electrodes

were used, along with a Pt auxiliary electrode, and a silver

reference electrode. E112 values are reported vs a

ferrocene/ferrecinium (Fe/Fe+) internal standard. aPlatinum

working electrodes were used, along with a Pt auxiliary

electrode, and a saturated sodium chloride calomel (SSCE)

reference electrode.

39

Table 3-8

Oxidation Potentials of Ruthenium Complexes

Complex

[Ru II (bpy) 2 ( tpbq) ] 2 +

[Run (bpy) 2 ( dppz) ] 2+

{ [Run (bpy) 2 ] 2 ( tpbq) } 4 +

{ [RUII (bpy} 2 ] 2 (dpq) }4+

{ [RUII (bpy) 2J 2 (dpp} }4+

El/2 (V vs SCE)

(no. electron)

+l.41 (le)

+1.24 (le)

+l.42 (2e)

+1. 47 ( 2e)

+1.39 ( 2e)

tpbq=2,2'-3,3'-tetra-2-pyridyl-6,6'-biquinoxaline. ref.4

dppz=dipyrido[3,2-a;2',3'-c]phenazine ref.3

dpq=2,3-bis(2-pyridyl)quinoxaline ref.8

dpp=dipyridyl pyrazine ref .5

40

Table 3-9

Redox Properties of Analogous Rutheniwn Complexes

complex oxidation Reduction

(mV) (mV)

1 2

[Ru II (bpy) 3] 2+a +l.29 -1. 33 -1.52

[Rurr (bpy) 2 (dppz)] 2 +a +l.24 -1.02 -1. 44

[Rurr (bpy) 2 (biphen) ] 2+ +l.38

{ [Rurrbpy) 2 ] 2 (biphen) } 4+ +l.34

adppz=dipyrido[3,2-a;2' ,3'-c]phenazine ref. 3

All data was taken in CH3CN

41

3

-1.76

-1. 67

4

-2.40

-2.07

References

1. Crutchley, R. J. Lever, A. B. Inorg. Chem. 1982, 21,

2276-2282.

2. Black, K. J.; Huang, H.; High, S.; Starks, L.; Olson,

M. and McGuire, M. E. Inorg. Chem. 1993, 32, 5591-5596.

3. Amouyl, E.; Homsi, A. J. Chem. Soc. Dalton. Trans.

1990, 1841-1845.

4. Rillema, D. P., Callahan, R. W.; Mack K. B. Inorg.

Chem. 1982, 21, 2589.

5. Braunstein, C. H.; Baker, A. D.; Streakas, T. C.;

Gafney, H. D. J. Inorg. Chem. 1984, 23, 857-864.

6. Campagna, S.; Denti, G.; Rosa, G. De; Sabatino, L.;

Ciano, M.; Balzani, V. Inorg. Chem. 1989, .£8., 2565-

2570.

7. Masschelein, A.; Mesmaeker, A. K.; Verhoeven C.;

Nasielski- Hinkens R. Inorg. Chim. Acta. 1987, ~'

L13-L16.

8. Carlson, D. L.; Murphy, W. R. Inorg. Chim Acta. 1991,

.1.8..L.. 61.

42

Fig

ure

2

-1

Th

e 1

H-N

MR

S

pectru

m

5-N

02 -l,1

0-p

hen

an

thro

line in

l ..

! I ,

,!u· ---:;~

J '

-

\ I I

( 1! 1 J Ii 111,

' i:11i1 •!I

.1 1 ~ : .

: ! ~ ;. .... '' '; i.: ... 1 ·

. ·11::.;

I 1

·"'

ii! I !)Jll i

' ' ~

~

___ __) l I

I I

I I

1 '

1 I

I I

I I

I I

I I

' I

' I

I I

I T

CD

Cl3

9.5

9

.0

8.5

8

.0

1.5

PPM

rt')

""'

Fig

ure

2-2

T

he

1H-N

MR

S

pectru

m o

f cru

de 5

,6-d

iam

ino

-1,1

0-p

hen

an

thro

line in

DM

SO

!1 fj •: I· :· I: 11 1: I

I I,: ;; f ., !. t t j;

t ~

' I ! ' I I I I

i

•I (

. . Jlj i.. •. i. ... ..I .._... ................ ",J.....-

.. .. ....... "

: ,

L _

_ j

f •

-..

1 ,

i i

i i

t i

j t

I I

j I

I I

I

ti,,,.; ...• :

·i •

I :

1 C

hi

qt

qt

Flg. 3-1

The St1uctu1e and Numbe1lng of I .J IO-phenanth10 I l ne

3

2 4

N s

6

8

45

Fig. 3-2

The St1uctu1e and Numbe1ing of 1,J 10-phenanthio Ii ne-5,J 6-d i one

3

2 4

1 N 0 s

1 0 0 6

g 7

8

46

Fig, 3-3

The St1uctu1e and Numbe1lng of biphen

3 3 '

2 4 4 ' 2 '

N S N S , N 1 ,

1 0 6 ' 1 0 '

g 7 7 ' g '

8 8 '

47

Fig, 3-4

CH3

N N

0

48

Fig, 3-5

The st1uctu1e of Dlpy11do[J,)2-a~2 '3 '-c] phenazlne (dppzJ

N N

49

Fig, 3-6

THe St1uctu1e of 2,) 3-b Is( 2-pyr I dy I)

--py1az1 ne

N

N

50

Fig. 3-7

The St1uctu1e of 2,J 5-b ls( 2-pyi i dy I)py1az 1 ne

N

51

N

/

N

/

N

Fig

ure

3

-8

Th

e 1

H-N

MR

S

pectru

m o

f 1

,10

-ph

en

an

thro

line in

C

DC

13

• l

I

1-,--T

---.-1

-,T

--i--.-'I

I

I I

I I

I I

I I

I I

I I

I I

I ,--, -,

9.5

9

.0

8.5

8

.0

7.5

7

. 0 P

PM

N

lf)

Fig

ure

3

-9

~-

-J.

J ~

J

I I

I I

I I

I -.---.

9.5

Th

e 1H

-NM

R S

pectru

m o

f 1,1

0-p

hen

an

thro

line-5

,6-d

ion

e in

CDC1

3

J

J .L

L

r· r .. ,

,..,. .. _,..

_)

•I

, I

'I

..

I I

I I

I I

I I

I I

I I

,---, -T

l r ~

9.0

8

.5

8.0

7

. 5 P

PM

r'l ll'l

_, I

I

1 I

·1

I

l p 1 ·~·· 1 ·o -1

1 1

"' l ·1 ~ i

l (0 1----r-~ l

i CP i ~1

0

Vl

--

54

w I

1--' 0

1)\JC. 0 002·0 '.)O., ·o ~-~~~~~~~~~~ ......... ~~~~~~~~~_,_~~~~~~~~~~ t.,r I ! -=> r .. ,

I I

i v. I ':::> ...... ':::> I

I

· [

J 0 0

VI 0 0

t

I ~1 o 'I I.

" r. H 11

"

-----'"--·-----"--·-~-~--·--- .... .....a......l-1.-.. . • ----"-"-~·-· -- •.•• 1. •• -··' --·--·.

55

I i l

l i j

( .:. :J ":' ) )•)0 • <) ')·;.:;'.. j ).) ., . ) ; p. )

Ji J ~ J

~, ·.:>

I I L. --c____ I '"r:l ' ..... I

l!l c . -N Ii

(D

VI w 0 0 I

I-' N

1

8 ::r (I)

~ 1 I ........

< ~ ..... 0 0 {ll

en ttj (I)

~ 0 :I rT 3 11 c a 0

V' Hi 0

tr 0 .....

1 ttj ::r (I)

i ::s

i ..... ::s (')

1 ::r:

-j w

.:]- (') ':::> z :>

'

I . ________ ..__·--·--·-···' -·-·-·--- ..... - _ _I

56

( ·_,·J~) it)') . fJ ') ~2 .. .} j i". j Vi'-" . ') )•) ·; ') J , , ,.,

':> -- ---0

!. I

~ '1j I-'· I

t.Q ~ s::

Ii I CD r w

; I I,,;

..... 0 ... 0 I w I I

i i 8 i ::r I CD j Cl I <: I I

1 <: I-'· ~

j rn 0 0

C/l 'O

CD 0

i rt ~

11 :;, i:: 3

i a

j 0 HI

lJ'I f\J 0

l 0

f\J I tr I-'· 'O ~ Ii I-'· 0. I-'· ::l CD

·:J' I-'· :> -t ::l ::> ! (') :I:

w (') z

57

C '.iO\;' 1

o•Vi ·o ')')2 · c) •.)').., . ) ;..n·) )j•=J.)

-0 ~-r-s ":> -1 "tJ I-'·

!· c_ lQ

I c I ~

1 ro w I

I I-'

i .::.

l.-4 0

1-3 0 :;:,' (I)

c: <: I

j <: ....... I rn

Ul ~

~ (I) 0 0 0 rt t-f ~ - s

:J 3 0

Hi

~ :;:,' (I) ::s

V1 ~ 0 N 0 ....... ::s (I)

I

i .......

i ::s I (') 1 ::x:

w (')

a- I z I •.J

1 ::;,

I

j

..• ='

-~------'- - i..___ .• _ ..... _ ' L

58

Fig.3-15

The St1uctu1e of [ Ru(bpyJ 2 (b i phenJ] C PF 6 J 2

N N

Ru(bpyJ 2

59

Fig. 3-16

The St1uctu1e of [Ru(bpy) 2 (biphen)J 2 CPF 6 J 4

Ru(bpyJ 2

60

"!j ..... "°

I ~ 11 (1)

' I I

w I

! I-' I I ...J I I I

I 8 ::r (1)

I-' ::c I

l "'\

~ l ~

o"l

~ ~

en ta (1) 0 rt

a

Ul I

s

1

0 HI

,.......,

a' -~ "< -N -(X) tr .....

0 ta ::r (1) :l -....... -......., "'d "!j

°' 'Jl -N

} I

..... :l

-....J 1 f \

(') :I:

w '::>

(') z

"'J '""J ?" .....

61

Fig

ure

3

-18

: T

he

1H

-NM

R S

pectru

m o

f [(b

py

2)R

u(b

iph

en

)Ru

(bp

y)

2](P

F6

)2

. I ,, ,, i: r! !1' ,, I I

f

I ··I :, r11

11 I I A.' ,, !

I I I I I I

,J,-

. : 'I

I' I.

! I '·

' 11

11 I

., 'lj1I

1i I ' .~[

: ll I

, jl.

J l~;I ~., ' '·~·.' I .. ;' ~

j.1., I~

•: r

~·I 1.; Ii

:j ll!

~I ~:

~11

, -,

-1

I -

, T

'-1

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I I

I ,-----,

N

\D

( :>Q~!

000·0 002·0 00""0 ()09. •j 009. :.i )1)1;. t '"':I

g f I-'· lO c "i "i

w I

..... \0

"' .. "'

.. "" '"3 0 ::r 0

(1)

c: < I < I-'· rn Cll

"a (1)

~ 0 rt 0 t'1 0

s:: s 0 - Hi ::i

3 ,....., ~ s:: -tr

"a I.JI "< 0 0 -"" -tr

I-'• "a ::r (1) ~ -........

~! ~ -"C "'%j

0

°' ':> -"" I I-'·

I ~ j I n I ::i::

I w n

I ·Z

'·I . .., ~-----·-

)

11 1 ) )• j ., '• ')1) .. ;, ... , . j·);

63

Fig

ure

3

-20

: T

he U

V-V

is Sp

ectr-um

of

[(bp

y2

)Ru

(bip

hen

)Ru

(bp

y)

2](P

F6

)2in

CH3

CN

L'

D

" ~.....,

t.r .--.

r·-

-----r·-

-r

-T

•

-,.--,--~--.,. -

· -

·-r·

--

r-

---1-

, I

0 •

0 20

0

30

0

40

0

50

0

60

0

~

<nm>

I .

\ I I

fro

f) ~.

.q< \D

Figure 3-21 The Cyclic Voltammogram [Ru(bpy) 2 (biphen)] (PF6 ) 2

a) J 1 µA

+1.80 mV 0.00

b)

11 µA

0.00 -1.70 m'

65

Figure 3-22 : The Cyclic Voltammogram

[ (bpy2 ) Ru ~biphen) Ru (bpy) 2 ) (PF6 ) 4

I 4 µA

+l.80mV

I 4 µA

... "":

0.00

66

0.00

-1. so mv

Fig

ure A

-I :

The

UV

-Vis

Sp

ectrum

of

S,6

-dia

min

o-1

,10

-ph

en

an

thro

line in

cH

3 CN

+1

.20

A

0.2

00

<

A/O

JI.).)

/ +0

.00

A,

20

0.0

I•

_,,,,.-;

,.,.

10

0 .0

< N

M/D

IU.)

,

•v_,,,.

-.... -.;;t

fl(

70

(

Fig

ure

A

-II T

he

IR

Sp

ectru

m o

f 5

,6-d

iam

ino

-1,1

0-p

hen

an

thro

line in

K

Br

I' N

~

: 1 NICOL

ET

ex.

•AM

PL

E

FIL

E

~ i I' I

Ill u 2

<I I

~ t <

lfl

I-II

I-..

... . I:

~

~

II z ~q " Ill II

" WI

nl 0 II

ID ..

---

-----+-----------

•oco

.o

3-'2

2. 2

28

44

.4

l.

12

/22

/94

1

21

39

10

9

'I

·--+---~....__ _

__

-----t 2

28

9.7

1

8-4

4. 4

1 !SS

!S. !S

12

99

.7

97

7.7

11

eaa.a

a

40

0.0

0

WA

VEN

UM

BR

R9

<CM

-1>

--id!

Fig

ure A

-III The

1 H

-NM

R S

pectru

m o

f 5

,6-d

iam

ino

-1,1

0-p

hen

an

thro

line in

DMSO

l ':• 1

!1

ji•! I·

i.:· . ,

l.

I•

• l

.·

l l

• I'

. 11,

LJL

~

J l

.,. T

T

' ·1

-'T

. ... '"T

... -.,.-----,-·-· T··-·,-·--·-,-----,----...,.---T

·--,----.--,---.--··--

,_, ,_, 1-f

<

The Synthesis and Characterization of [RuII (bpy) 2 ...

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