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Journal of Organometallic Chemistry 696 (2011) 748e757

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Journal of Organometallic Chemistry

journal homepage: www.elsevier .com/locate/ jorganchem

Reactivity of TpMe2Ir(C2H4)(DMAD) with carboxylic acids. A DFT study ongeometrical isomers and structural characterization

Verónica Salazar a,*, Gloria Sánchez-Cabrera a,*, Francisco J. Zuno-Cruz a, Oscar R. Suárez-Castillo a,Julián Cruz a, Rosa Padilla a, Martín Hernández a, Arián E. Roa a, Celia Maya b, Marco A. Leyva c,María J. Rosales-Hoz c, Pandiyan Thangarasu d

aCentro de Investigaciones Químicas, Universidad Autónoma del Estado de Hidalgo, Ciudad Universitaria, Km 4.5 Carretera Pachuca-Tulancingo, 42184 Pachuca, Hidalgo, Méxicob Instituto de Investigaciones Químicas, Departamento de Química Inorgánica, Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Sevilla, Avenida AméricoVespucio 49, Isla de la Cartuja, 41092 Sevilla, SpaincDepartamento de Química, Centro de Investigación y de Estudios Avanzados del I.P.N., Avenida Instituto Politécnico Nacional 2508, Col San Pedro Zacatenco, 07360 México D. F.,Méxicod Facultad de Química, Universidad Nacional Autónoma de México (UNAM), Ciudad Universitaria, Coyoacán, 04510, México D.F., México

a r t i c l e i n f o

Article history:Received 30 July 2010Received in revised form27 September 2010Accepted 28 September 2010Available online 8 October 2010

Keywords:Alkyne insertionTpMe2 iridium complexesDimethylacetylene dicarboxylateCeH activationDFT calculations

* Corresponding authors. Tel.: þ52 771 1550933/þþ52 771 717200x6502.

E-mail address: salazar@uaeh.redaueh.mx (V. Sala

0022-328X/$ e see front matter � 2010 Published bydoi:10.1016/j.jorganchem.2010.09.073

a b s t r a c t

The thermally unstable adduct TpMe2Ir(C2H4)(DMAD), which was generated “in situ” by the reaction ofDMAD with TpMe2Ir(C2H4)2 (1) at low temperature, reacted with different carboxylic acids to produce thefollowing compounds: TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(H2O)(OC(O)C6H4R), (R ¼ H, 2a; o-OH, 2b; o-Cl,2c; m-Cl, 2d; o-NO2, 2e; m-NO2, 2f; o-Me, 2g; p-Me, 2h) and TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(H2O)(OC(O)Me) 3. In the reaction of derivative 2a with Lewis bases, TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(L)(OC(O)C6H5), (L ¼ Py, 4a; m-BrePy, 4b; m-ClePy, 4c; NCMe, 5) were obtained, of which 4b and 4c were isolatedas a mixture of two isomers in which the substituted pyridine ring was present at different rotationalorientations. All new compounds prepared were characterized by 1H and 13C{1H} NMR spectroscopy, thestructure of compounds 2d, 2h and 4a being determined by X-ray diffraction analysis. DFT was used toanalyze the relative stability and the structural orientation of the isomers.

� 2010 Published by Elsevier B.V.

1. Introduction

The insertion of unsaturatedmolecules into MeH orMeC bondsis an important reaction in organometallic chemistry [1]; inparticular, alkynes constitute interesting building blocks in metal-mediated organic synthesis of compounds that possess manyindustrial applications [2]. In previous studies, it has been clearlyshown that the presence of a Tp0 ligand in a metal compound (Tp0

stands for any type of hydrotris(pyrazolyl)borate ligand) favorsoctahedral coordination [3e6], thus, for TpMe2Ir derivatives, the þ3oxidation state is favorable [7,8]. The reaction of the Ir(I) olefinderivative TpMe2Ir(C2H4)2 with dimethylacetylene dicarboxylate(DMAD) forms the mixed adduct TpMe2Ir(C2H4)(DMAD) at lowtemperature and it is stable below 10 �C [9]; above this tempera-ture, in the absence of other reagents, it evolves by CeH activationof the ethylene, as observed for other related derivatives of

52 771 7172000x2204; fax:

zar).

Elsevier B.V.

composition TpMe2Ir(C2H4)(L) (L ¼ C2H4, PR3, .) [8e10]. This is incontrast with TpMe2Ir(C2H4)(DMAD), where it forms an iridacyclo-pentene by the oxidative coupling of the two unsaturated ligands[11]. The ethylene ligand in the TpMe2Ir derivative is weaklybonded, and can be easily replaced by other Lewis bases [9].

An early example of the insertion of DMAD into an IreH bondreported the formation of an E-alkenyl derivative by the reaction ofIr(H)(CO)(PPh3)3 with DMAD [12]; similarly, the insertion of thisalkyne into Meacyl or Mearyl bonds is also known [13,14], as wellas for other insertions, that finally yield alkenyl derivatives [15,16].In this paper, we report the reaction of the above mentioned Ir(I)derivative TpMe2Ir(C2H4)(DMAD) with aliphatic and aromaticcarboxylic acids to produce the E-alkenyl iridium complexesTpMe2Ir(E-C(CO2Me)]CH(CO2Me))(H2O)(OC(O)C6H4R), (R ¼ H, 2a;o-OH, 2b; o -Cl, 2c;m-Cl, 2d; o-NO2, 2e;m-NO2, 2f; o-Me, 2g; p-Me,2h) and TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(H2O)(OC(O)Me) (3) asthe result of the insertion of the alkyne into the hypothetical IreHbond formed upon protonation of the metal compound by thecorresponding acid. Furthermore, the adducts TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(L)(OC(O)C6H5), (L ¼ Py, 4a; m-BrePy, 4b;

CO2H

R

BN N NN N N

Ir

H

TpMe2Ir [Ir]

MeO2CC CCO2Me1.

CH2Cl2, -10 °C 25 °C

2.

CH2Cl2, H2O, r.t.

O

O

[Ir]

O

Me

O

Me

O

OH2

O

R

2

3

45

7

8

9

10

11

1

2a: R = H2b: R = o-OH2c: R = o-Cl2d: R = m-Cl2e: R = o-NO22f: R = m-NO22g: R = o-Me2h: R = p-Me

1

6

13

12

[Ir]

Scheme 1. Synthesis of Irida-E-alkenyl compounds 2aeh.

O

O

Me

1- DMADCH2Cl2, -10 oC

3 (3-d3)

O

O

[Ir]

O

Me

O

Me

OH2(D2O)

H(D)

1

[Ir]

2- MeCO2H(MeCO2D) H2O(D2O)

Scheme 2. Irida E-alkenyl aqua complexes 3 and 3-d3.

V. Salazar et al. / Journal of Organometallic Chemistry 696 (2011) 748e757 749

m-ClePy, 4c; NCMe, 5) were synthesized by the reaction of theconvenient precursor with the appropriate Lewis base. The exis-tence of two isomers of compounds 4b and 4c was found in solu-tion by NMR, and DFT calculations were used to analyze theirstructural orientation.

2. Results and discussion

2.1. Synthesis and characterization of irida-E-alkenyl compounds

In the reaction of TpMe2Ir(C2H4)2 (1) dissolved in CH2Cl2 withDMAD (1.0 equiv amount) and then with 1.0 equiv amount ofa substituted benzoic acid at low temperature (�10 �C), E-alkenylderivatives 2ae2h were obtained (Scheme 1). These derivatives

O

O

Ar

1 eq DMAD

-20° C

[Ir]

A

O

O

[Ir]

O

Me

O

Me

OH2

H

O

O

Me

OO

Me1

[Ir]

Ar = C6H4-R , 2

Ar = Me, 3

Scheme 3. Proposed stepwise form

exhibit a high thermal stability since they experience no structuraltransformation when heated in cyclohexane at 150 �C.

The above scheme shows that the two C2H4 molecules in thestarting material have been replaced by alkenyl and carboxylateligands and the final compounds satisfy the 18 e� count by thecoordination of a molecule of adventitious water. Once the pres-ence of water in the final products was realized, the reactionswere carried out by adding a slight excess of this reagent. The use ofthose different carboxylic acids has revealed that there is nosignificant change in the chemical reactivity varying the electron-donors OR withdrawing substituent.

The NMR data confirm the structure proposed for compounds 2.For 2a, in the 1H NMR spectrum, a signal at low field (9.12 ppm)accounts for the coordinated water molecule, while the alkenylhydrogen (4-H) resonates at 4.62 ppm. In the 13C{1H} NMR, thecarboxylate ester carbons give rise to singlets at 180.8 and163.4 ppm, while the signal at 181.9 ppm is assigned to thecarboxylate carbon of the former acid. The resonances for twoalkenyl carbons are found at 152.1 (IreC(R)) and 126.7 ppm (IreC(R)]C(H)(R)).

When the reaction (Scheme 1) was performed with acetic acidinstead of a benzoic one, a new derivative TpMe2Ir(MeCO2C]CHCO2Me)(H2O)(OCOMe) (3, Scheme 2) was obtained. A deuteriumlabeled isotopic experimental using D2O and MeCO2D was

[Ir]

H

B

[Ir]

O

ArO

C

H2O

O

O

Me

O

OMe

O

O

O

Me

O

Me H

+

-C2H4

MeCO2H

carboxylatecoordination

ation of compounds 2 and 3.

O

O

[Ir]

O

Me

O

Me

O

O

23

45

71

6N

O

O

[Ir]

O

Me

O

Me

O

OH2

O

60 °C, 12 hr

89

10

1112

1314

15

1617

18

N

MeCN60 °C, 12 hr

5

2a

4a: R = H4b: R = Br4c: R = Cl

O

O

[Ir]

O

Me

O

Me

O

O

23

45

71

6NCMe

89

10

1112

13

14

15

R

R

Scheme 4. The reaction of the Ir-derivative 2a with Lewis bases.

Fig. 1. Energetic profile of rotamers IeIV.

V. Salazar et al. / Journal of Organometallic Chemistry 696 (2011) 748e757750

Fig. 2. Structures of the two most stable conformers II and IV.

V. Salazar et al. / Journal of Organometallic Chemistry 696 (2011) 748e757 751

performed to show that the source of the proton of the E-alkenylligand was from the acid.

The formation of complexes 2 and 3 can then be proposedas shown in Scheme 3. The known TpMe2Ir(C2H4)(DMAD) [9,17]is initially formed (it is in fact observed in monitoring the reac-tion by NMR, CD2Cl2, �40 �C), to be protonated by the acid.Subsequent migratory insertion of the alkyne into the IreH bond,replacement of the ethylene by the corresponding carboxylate,and coordination of water, would yield the final products.

Fig. 3. Space filling diagram of the two most stable conformers IV (4b0) and II (4b00).

2.2. Reactivity of the irida-E-alkenyl 2a towards Lewis bases

The reactions of 2a with pyridine (Py) and its monosubstitutedderivatives (m-BrePy, m-ClePy) or with acetonitrile (MeCN)were carried out in order to determine its chemical behavior inthe presence of Lewis bases. These reactions provide theadducts TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(NC5H4R)(OC(O)C6H5)(R ¼ H, 4a; m-Br, 4b; m-Cl, 4c) and TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(NCMe)(OC(O)C6H5) (5) in high yields (�90%, Scheme 4).

The structure proposed for compounds 4 and 5 is assigned onthe bases of NMR and X-ray analyses (see below). The pyridinederived compound 4a exhibits five different signals for the pyridineprotons in the 1H NMR spectrum, thus indicating a restrictedrotation around the IreN(Py) bond. The signal for the alkenylproton appears at 4.52 ppm, in the same region as the parentcompounds 2. In the reactions of 2awith the halogenated pyridines(m-BrePy or m-ClePy), compounds 4b and 4c are formed,respectively. The 1H NMR spectra recorded for the compoundsshow that there are two different sets of signals (see Experimentalsection) in each case, corresponding to two different products,possibly two isomers having different pyridine ring orientations,due to restricted rotation around the IreN.

A variable temperature NMR study (from 25 to 70 �C) shows noexchange between the two sets of signals in each case. Althoughwewere unable to separate both isomers, 2D-NOESY NMR spectraindicate for the major isomer in each case, a correlation betweenthe pyridine 14-H (the H atom in the ortho position close to the

halide substituent) and the carboxylate 9-H and H-13 atoms,indicating that the major isomer in both cases is the one withthe halide substituent in the pyridine being close to the carboxylateligand phenyl ring.

3. DFT geometrical analysis of compound 4b

In order to analyze the pyridine ring orientations in compound4b, DFT was used to analyze its structural parameters. First a partialoptimization for 4b was performed by DFT; then the rotationalbarrier over the equatorial plane (OeIreNPyeCPy) was obtainedto generate the different rotamers. In the rotation process, atevery 20� change, the geometry was optimized and the resultingstructures are presented in Fig. 1. In the potential energy surface(PES) analysis, it was found that there are two low energy rotamersthat have an energy difference of 0.5 kcal mol�1. The stableconformer 4b0 (structure IV) (Fig. 1) was found at a rotational angleof 340�, and another isomer 4b00 (structure II) (Fig. 1) at 160� wasdetected. In conformer 4b0, the bromine atom attached to thepyridine ring is nearest to benzoate group, while for the otherisomer 4b00, the bromine atom is placed on the opposite side of thebenzoate group. Furthermore, other higher energy conformers

Me

Ir

O

O

O

Me

O Me

4b´´ (II)

NBr O

O

N

N

N

N

NN

B

H

O

OIr

OO

Me

4b´ (IV)

N

Br O

O Me

N

N

N

N

NN

B

H

Scheme 5. Structure proposed of 4b0 and 4b00 complexes.

Fig. 5. ORTEP view of compound 2h (30% probability level, H atoms except for waterare omitted for clarity).

V. Salazar et al. / Journal of Organometallic Chemistry 696 (2011) 748e757752

(structures I at 60� and III at 240�) are shown (Fig. 1). For thestructures II and IV, a full optimization was performed by usingdifferent functionals (LDA, PW91 and PBE) with base sets TZP andthe results show that structure IV (4b0) is more stable than that of II(4b00) having an energy difference about 0.33e0.6 kcal/mol; thisobservation is in agreements with the NMR results that the stableisomer is IV (4b0).

The stable conformers [II (4b00) and IV (4b0)] exhibit a distortedoctahedral geometry (Fig. 2). The bond distances obtained forconformer IIwere: IreNTp¼1.97, 2.03and2.09�AandIreNPy¼2.09�A,and for conformer IV, IreNTp ¼ 2.05, 2.06 and 2.13 �A andIreNPy¼2.08�A. Inbothstructures, theexistenceofnon-conventionalhydrogenbonds, i.e., CeHeO¼ 2.03�A andCeHeN¼ 2.04�A for II andCeHeO ¼ 2.00 �A and CeHeN ¼ 2.44 �A for IV, is established. Thetheoretical geometrical data are in good agreement with thatobserved in the X-ray structure of compound 4a.

Since the energy barrier between the stable conformers [II (4b00)and IV (4b0)] is high (13.8 kcal mol�1), (Fig. 2) the inter-conversionbetween one isomer and another turns out to be a difficult process,and there is also a steric hindered congestion between thesubstituted pyridine ring and other neighboring groups; as seen inFig. 3. Therefore; compounds 4b0 and 4b00 are produced separatelywith different pyridine ring orientations. This observation is in

Fig. 4. ORTEP view of compound 2d (30% probability, H atoms except for water areomitted for clarity).

agreement with the variable temperature NMR results in that nointer-conversion of isomer 4b0 to 4b00 is observed. From the abovestudies, we propose that the major isomer 4b0 is assigned to theconformer IV while other isomer 4b00 corresponds to conformer II(Scheme 5). Similarly, for compounds 4c0 and 4c00, the samecalculation method was employed, the results were almost sameas those observed for 4b; this suggests that the existence of thesame type of geometrical rotamers for 4c is manifested. Further-more, since the non-conventional hydrogen bonds that arepresent in the structure can also contribute to the prevention of therotation of the pyridine ring, the presence of two conformers in theNMR solution is confirmed.

4. X-ray diffraction studies

Suitable crystals for compounds 2d, 2h and 4a were obtainedand their solid-state structures were determined by X-ray diffrac-tion analysis.

4.1. Complexes 2d and 2h

ORTEP views of 2d and 2h are shown in Figs. 4 and 5, respec-tively while Table 1 shows selected bond lengths [�A] and angles [�]for compounds 2 and 4a. Both compounds 2 exhibit a distortedoctahedral coordination, as expected for these Ir(III) derivatives[7,18]. The alkenyl bonds C(18)eC(19) have typical values for C]Cdouble bonds [19] (1.349(7) for 2d and 1.350(8) for 2h). The threedistances to iridium Ir(1)eC(18), Ir(1)eO(6) and Ir(1)eO(1), withvalues of 2.031(5) 2.089(3) and 2.099(3) �A for 2d and 2.019(6),2.069(4) and 2.094(4) �A for 2h, fall in the range of a single bond.Because of the higher trans influence of alkenyl ligand in compar-ison with the two o-donor ligands water and carboxylate, the IreN(pyrazolyl) bonds trans to the oxygen atoms (2.0225 av 2d and 2h)are shorter than the distance trans to the carbon atom C(18) (2.148av 2d and 2h) and 2h [9].

In both structures, the presence of a hydrogen bond betweenoxygen (benzoic acid) and hydrogen atoms (water molecule) wasobserved. The H-bond distance O(7)eH(1B) ¼ 1.811�A for 2d and O

Table 1Selected bond lengths [�A] and angles [�] for compounds 2d, 2h and 4a.

2d 2h 4a

Bond lengthsMolecule 1 Molecule 2

Ir(1)eN(6) 2.154(4) 2.142(5) 2.130(4) 2.134(4)Ir(1)eN(2) 2.025(4) 2.012(4) 2.031(5) 2.036(5)Ir(1)eN(4) 2.026(4) 2.027(4) 2.040(4) 2.038(4)Ir(1)eO(1) 2.099(3) 2.094(4) e e

Ir(1)eO(6) 2.089(3) 2.069(4) 2.047(4) 2.050(4)Ir(1)eC(18) 2.031(5) 2.019(6) 2.056(6) 2.039(6)C(18)eC(19) 1.349(7) 1.350(8) 1.349(8) 1.328(8)C(22)eC(23) 1.514(8) 1.514(7) 1.501(8) 1.507(8)C(25)eCl(1) 1.730(9) e e e

Ir(1)eN(7) e e 2.068(4) 2.071(4)

Bond anglesMolecule 1 Molecule 2

O(7)eC(22)eO(6) 126.4(5) 126.2(6) 127.0(5) 125.8(5)C(18)eC(17)eO(2) 111.3(5) 124.9(6) 112.7(5) 111.5(5)C(18)eC(17)eO(3) 124.2(5) 111.8(6) 124.9(5) 124.5(5)C(19)eC(20)eO(5) 110.5(5) 111.7(6) 110.1(5) 110.2(5)C(19)eC(18)eC(17) 118.6(4) 119.4(6) 117.5(5) 118.5(5)N(2)eIr(1)eN(4) 90.29(16) 90.47(17) 89.16(18) 88.15(17)N(2)eIr(1)eN(6) 88.68(16) 86.44(18) 88.30(18) 88.34(17)N(4)eIr(1)eN(6) 86.24(15) 88.14(19) 87.80(17) 88.22(17)N(2)eIr(1)eO(1) 88.49(15) 178.91(16) e e

N(4)eIr(1)eO(1) 177.39(14) 90.47(17) e e

N(2)eIr(1)eO(6) 176.98(14) 86.44(18) 177.66(16) 178.23(17)N(4)eIr(1)eO(6) 89.26(14) 175.83(18) 93.16(16) 92.82(16)N(6)eIr(1)eC(18) 176.15(17) 175.40(2) 175.8(2) 177.0(2)N(6)eIr(1)eO(6) 88.31(15) 88.07(18) 91.46(16) 93.17(16)N(4)eIr(1)eC(18) 90.63(17) 89.1(2) 89.2(2) 90.2(2)N(2)eIr(1)eC(18) 89.11(18) 89.9(2) 88.6(2) 89.0(2)N(4)eIr(1)eN(7) 174.62(18) 174.20(18)C(18)eIr(1)eO(6) 93.89(17) 94.5(2) 91.66(19) 89.53(19)O(6)eIr(1)eO(1) 91.84(14) 91.47(16) e e

C(18)eIr(1)eO(1) 91.65(17) 90.7(2) e e

O(6)eIr(1)eN(7) e e 83.0(16) 86.11(16)C(18)eIr(1)eN(7) e e 96.1(2) 95.4(2)

Fig. 6. ORTEP view of compound 4a (molecule 1) (30% probability level, H atoms areomitted for clarity).

V. Salazar et al. / Journal of Organometallic Chemistry 696 (2011) 748e757 753

(7)eH(1A) ¼ 1.712(5)�A for 2hwas seen to be smaller than the sumof their Van der Waals radii (SVwROeH ¼ 2.72 �A) [20] and greaterthan the sum of covalent radii (SCROeH ¼ 0.97 �A) [21].

4.2. Complex 4a

For the case of 4a, two molecules are present in the asymmetricunit cell. Fig. 6 shows an ORTEP view for one of these molecules.The distortion of the octahedral geometry, characteristic of TpMe2Ir(III) derivatives, is shown by the deviation of the bond angles: N(2)eIr(1)eN(4) ¼ 89.16(18)�, N(2)eIr(1)eN(6) ¼ 88.30(18)�, N(4)eIr(1)eN(6) ¼ 87.80(17)�. Furthermore, the angle for C(18)eIr(1)eN(7) ¼ 96.1(2)� is greater than that observed for C(18)eIr(1)eO(1),91.65(17)� and 90.7(2)� for 2d and 2h, respectively. The shortestangle obtained for O(6)eIr(1)eN(7) 83(16)� is due to the bulkyligand (Py vs. H2O) in 4a, implying that the pyridine ring is arrangedin such a way that it interacts with hydrogen atoms of methylpyrazolyl fragment (H-4a and H-14c): (H’s(Pz),Py: 3.413 (15) and3.030(21) �A). Once more, the bond length of Ir(1)eN(6), of 2.130(4) �A, is larger to the other two distance from Ir to the N atoms ofthe pyrazolyl rings, due to the larger trans influence of the alkenylligand coordinated trans to N(6).

The bond distance C(18)eC(19) (1.349(8) �A) observed in 4a issimilar to that found in compounds 2d and 2h, thus indicating thatthe coordination nature of E-alkenyl fragment is not affected bycoordinating the Lewis base to the metal ion. Furthermore, otherbond lengths Ir(1)eC(18) 2.057(6), Ir(1)eO(6) 2.048(4) and Ir(1)eN(7) 2.068(5) �A are characteristic of single bonds. It is noticed thatthe carboxylate carbonyl group is symmetrically located between

two pyrazolyl rings, having a short contact with the CH2Cl2 mole-cule [H0s(CH2Cl2)/O(7): 2.3726(1) and 2.7037(1) �A].

5. Conclusions

The Ir(1) adduct TpMe2Ir(C2H4)2(DMAD) reacts with a variety ofcarboxylic acids to yield alkenyl derivatives of the DMAD ligand,with displacement of the olefin. The products formed, whichcontain the alkenyl moiety, the carboxylate ligand and a coordi-nated molecule of water, have been shown to react with Lewisbases, this reagent substituting for the labile water. For the case oftwo derivatives containing benzoate and m-substituted pyridines,two sets of isomers are formed, which are derived from restrictedrotation of the coordinated Lewis base. DFT studies were performedto analyze the nature of the mentioned isomers.

6. Experimental section

6.1. General procedures

All experiments were performed under a nitrogen or an argonatmosphere using conventional Schlenk techniques. Solvents weredried, degassed and then used for the experimental studies. Theprepared compounds were purified by flash column chromatog-raphy using silica gel (Merck 60, 230e400 mesh). Mass spectrawere recorded at Mass Service unit, university of Sevilla, Spain(FAB/High Resolution) and at CINVESTAV-México (HR-LC 1100/MSDTOF Agilent Technology equipment). Elemental analyses wereobtained in a PerkineElmer series II Analyzer 2400. Infrared spectrawere recorded for the complexes in the solid state as KBr pellets ona PERKIN Elmer 2000 FT-IR instrument. NMR spectra are measuredon JEOL Eclipse 400, Bruker DRX-500, DRX-400, DPX-300 andVARIAN 400 spectrometers in CDCl3. The 1H or 13C residual reso-nance signal of the solvent was used as an internal standard, butchemical shifts are reported with respect to TMS. Most of the NMRassignments are based on the extensive 1He1H decoupling exper-iments, and homo and heteronuclear two-dimensional spectra.The complexes TpMe2Ir(C2H4)2 (1) and TpMe2Ir(C2H4)(DMAD)were prepared according to published procedure [8,9].

V. Salazar et al. / Journal of Organometallic Chemistry 696 (2011) 748e757754

6.2 General procedure for the synthesis of the iridium complexesTpMe2Ir(E-C(CO2Me)]CH(CO2Me))(H2O)(OC(O)C6H4R), (R ¼ H, 2a;o-OH, 2b; o-Cl, 2c; m-Cl, 2d; o-NO2, 2e; m-NO2, 2f, o-Me, 2g peMe,2h) and TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(H2O)(OC(O)Me) (3)

To the compound TpMe2Ir(C2H4)2 (1) dissolved in CH2Cl2 (5 ml),at �10 �C, DMAD (1 equiv) was added. The respective mixture wasstirred for 10 min and then 1.0 equiv amount of aromatic oraliphatic carboxylic acid was added. The mixture was allowed toreach the room temperature (25 �C) and then it was stirred for 14 h.The solvent was removed under low pressure. The productobtained was washed with pentane (10 ml), and dried undervacuum.

6.3. TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(H2O)(OC(O)C6H5) (2a)

The above procedure was employed for the preparation of 2a.The following compounds were used: TpMe2Ir(C2H4)2 (1) (50 mg;0.091 mmol), DMAD (11.2 mL; 0.091 mmol), benzoic acid (11.1 mg;0.091 mmol) and CH2Cl2 (3.0 mL). Yield: (solid, 62.9 mg, 89%). 1HNMR (CDCl3): d ¼ 9.12 (br s, 2H, H2O), 7.93 (d, 2H, 3JHeH ¼ 7.7 Hz,9-H, 13-H), 7.43 (t, 1H, 3JHeH ¼ 7.4 Hz, 11-H), 7.33 (t, 2H,3JHeH ¼ 7.7 Hz, 10-H, 12-H), 5.86, 5.83, 5.75 (3s, 1H each, 3CHPz),4.62 (s, 1H, 4-H), 3.72 (s, 3H, 1-CH3), 3.59 (s, 3H, 6-CH3), 2.48, 2.45,2.40, 2.27, 2.24, 2.19 (6s, 3H each, 6CH3Pz). 13C{1H} NMR (CDCl3):d ¼ 181.9 (C-7), 180.8 (C-2), 163.4 (C-5), 152.1 (C-3), 152.1, 151.3,151.2, 144.3, 144.1, 144.0 (6CqPz), 134.1 (C-8), 131.5 (1JCeH¼ 159.8 Hz,C-11), 129.3 (1JCeH ¼ 161.5 Hz, C-9, C-13), 127.8 (1JCeH ¼ 152.6 Hz, C-10, C-12), 126.7 (1JCeH ¼ 166.1 Hz, C-4), 108.4, 108.2, 107.7,(1JCeH ¼ 174.4 Hz, 3CHPz), 52.1 (1JCeH ¼ 146.8 Hz, CH3-1), 50.9(1JCeH ¼ 146.1 Hz, CH3-6), 14.6, 13.5, 12.7, 12.3 (in a 1:1:3:1 ratiorespectively) (1JCeH ¼ 128.4 Hz, 6CH3Pz). IR (KBr): n ¼ 3388 (H2O),2948 (CH3), 2533 (BH), 1714 (CO) cm�1. HR-MS (ESI-TOF) calcd forMHþ (C28H37BN6O7Ir) 773.2440, MHþ found 773.2458.

6.4. TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(H2O)(OC(O)C6H4oeOH)(2b)

According to the above mentioned procedure, compound 1(50 mg; 0.091 mmol), DMAD (11.2 mL; 0.091 mmol), salicylic acid(11.1 mg; 0.091 mmol) and CH2Cl2 (3 mL) were used to prepare thecomplex 2b. Yield: (solid, 33.1 mg, 46%). 1H NMR (CDCl3): d ¼ 11.40(br s, 1H, OH), 8.40 (br s, 2H, H2O), 7.69 (dd, 1H, 3JHeH ¼ 7.9,4JHeH ¼ 1.8 Hz, 13-H), 7.31 (td, 1H, 3JHeH ¼ 7.3, 4JHeH ¼ 1.8 Hz, 11-H),6.87 (dd, 1H, 3JHeH ¼ 8.0, 4JHeH ¼ 1.2 Hz, 10-H), 6.73 (td, 1H,3JHeH ¼ 7.3, 4JHeH ¼ 1.2 Hz, 12-H), 5.87, 5.84, 5.76 (3s, 1H each,3CHPz), 4.60 (s, 1H, 4-H), 3.75 (s, 3H, 1-CH3), 3.58 (s, 3H, 6-CH3),2.49, 2.45, 2.41, 2.24, 2.16, (6s, 1:1:1:2:1, 3H each, 6CH3Pz). 13C{1H}NMR (CDCl3): d ¼ 183.0 (C-7), 181.2 (C-2), 163.5 (C-5), 160.4 (C-9),152.1, 151.4, 151.3, (3CqPz), 151.1 (C-3), 144.6, 144.5, 144.3 (3CqPz),134.3 (1JCeH ¼ 158.4 Hz, C-11), 131.3 (1JCeH ¼ 164.4 Hz, C-13), 127.1(1JCeH ¼ 166.1 Hz, C-4), 118.7 (1JCeH ¼ 162.2 Hz, C-12), 117.1(1JCeH ¼ 163.7 Hz, C-10), 116.4 (C-8), 108.6, 108.4, 107.9,(1JCeH ¼ 176.1 Hz, 3CHPz), 52.1 (1JCeH ¼ 147.60 Hz, CH3-1), 51.1(1JCeH ¼ 146.0 Hz, CH3-6), 14.7, 13.6, 12.8, 12.7, 12.4 (in a 1:1:2:1:1ratio respectively) (1JCeH ¼ 128.3 Hz, 6CH3Pz). IR (KBr): n ¼ 3439(H2O), 2949 (CH3), 2534 (BH), 1696 (CO) cm�1. HR-MS (ESI-TOF)calcd for MHþ (C28H37BN6O8Ir) 789.2389, found 789.2369.

6.5. TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(H2O)(OC(O)C6H4oeCl) (2c)

According to the above procedure, compound 2c was obtainedby using compound 1 (50 mg; 0.091 mmol), DMAD (11.2 mL;0.091 mmol), o-chlorobenzoic acid (14.3 mg; 0.091 mmol) andCH2Cl2 (3.0 mL). Yield: (solid, 36.1 mg, 49.0%). 1H NMR (CDCl3):

d ¼ 8.70 (br, s, 2H, H2O), 7.71 (dd, 1H, 3JHeH ¼ 7.7, 4JHeH ¼ 1.5 Hz,13-H), 7.24 (dd, 1H, 3JHeH ¼ 8.0, 4JHeH ¼ 1.1 Hz, 10-H), 7.19 (td, 1H,3JHeH ¼ 7.3, 4JHeH ¼ 1.8 Hz, 11-H), 7.10 (td, 1 H, 3JHeH ¼ 7.40,4JHeH ¼ 1.1 Hz, 12-H), 5.78, 5.72, 5.67 (3s, 1H each, 3CHPz), 4.53(s, 1H, 4-H), 3.79 (s, 3H, 1-CH3), 3.52 (s, 3H, 6-CH3), 2.37, 2.36, 2.32,2.27, 2.17, 2.14 (6s, 3H each, 6CH3Pz). 13C{1H} NMR (CDCl3): d¼ 179.8(C-7),179.7 (C-2),162.4 (C-5), 151.0, 150.5,150.3 (3CqPz), 150.3 (C-3),143.3, 143.1, 143.0 (3CqPz), 133.3 (C-8), 131.3 (C-9), 130.1(1JCeH ¼ 164.0 Hz, C-13), 129.9 (1JCeH ¼ 162.9 Hz, C-11), 129.6(1JCeH ¼ 166.9 Hz, C-10), 126.1 (1JCeH ¼ 166.1 Hz, C-4), 125.1(1JCeH¼ 163.0 Hz, C-12),107.3,107.1,106.6 (1JCeH¼ 175.2 Hz, 3CHPz),51.5 (1JCeH ¼ 147.6 Hz, CH3-1), 49.9 (1JCeH ¼ 146.8 Hz, CH3-6), 13.9,12.4, 12.3, 11.6, 11.3 (in a 1:1:1:2:1 ratio respectively)(1JCeH ¼ 129.2 Hz, 6CH3Pz). IR (KBr): n ¼ 3426 (H2O), 2925 (CH3),2532 (BH), 1719 (CO) cm�1. HR-MS (FAB) calcd for MHþ

(C28H35BClN6O7Ir) 807.2056, found 807.2097.

6.6. TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(H2O)(OC(O)C6H4m-Cl)(2d)

Similarly, compound 1 (50 mg; 0.091 mmol), DMAD (11.2 mL;0.091 mmol), m-chlorobenzoic acid (14.4 mg; 0.091 mmol) andCH2Cl2 (3.0 mL) were used to prepare the complex 2d. Yield: (solid,50.2 mg, 68%). 1H NMR (CDCl3): d ¼ 8.83 (br s, 2H, H2O), 7.82 (t, 1H,4JHeH ¼ 1.7 Hz, 9-H), 7.73 (td, 1H, 3JHeH ¼ 8.1, 4JHeH ¼ 1.5 Hz, 13-H),7.32 (ddd, 1H, 3JHeH ¼ 8.1, 4JHeH ¼ 2.2, 1.1 Hz, 11-H), 7.18 (t, 1H,3JHeH ¼ 8.1 Hz, 12-H), 5.79, 5.76, 5.67 (3s, 1H each, 3CHpz), 4.53(s, 1H, 4-H), 3.64 (s, 3H, 1-CH3), 3.51 (s, 3H, 6-CH3), 2.41, 2.37, 2.33,2.19, 2.15, 2.09 (6s, 3H each, 6CH3pz). 13C{1H} NMR (CDCl3):d ¼ 179.7 (C-2), 179.3 (C-7), 162.4 (C-5), 150.5 (C-3), 151.0, 150.3,150.2, 144.3, 143.2, 143.1 (6CqPz), 134.9 (C-8), 132.9 (C-10), 130.5(1JCeH ¼ 166.10 Hz, C-11), 128.3 (1JCeH ¼ 167.6 Hz, C-9), 128.1(1JCeH ¼ 163.0 Hz, C-12), 126.3 (1JCeH ¼ 168 Hz, C-13), 125.8(1JCeH ¼ 165.30 Hz, C-4), 107.4, 107.2, 106.7, (1JCeH ¼ 174.5 Hz,3CHPz), 51.1 (1JCeH ¼ 146.8 Hz, CH3-1), 49.8 (1JCeH ¼ 146.0 Hz, CH3-6), 13.6, 12.4, 11.7, 11.3 (in a 1:1:3:1 ratio respectively)(1JCeH ¼ 129.0 Hz, 6CH3Pz). IR (KBr): n ¼ 3426 (H2O); 2925 (CH3),2533 (BH), 1715 (CO) cm�1. HR-MS (FAB) calcd for MHþ

(C28H36BClN6O7Ir) 807.2056, found 807.2087.

6.7. TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(H2O)(OC(O)C6H4oeNO2)(2e)

For complex 2e, compound 1 (50 mg; 0.091 mmol), DMAD(11.2 mL; 0.091 mmol), o-nitrobenzoic acid (15.3 mg; 0.091 mmol)and CH2Cl2 (3 mL) were employed. Yield: (solid, 66.0 mg, 88.2%). 1HNMR (CDCl3): d ¼ 8.42 (br, s, 2H, H2O), 7.93, 7.50 (m, 4-H, 10-He13-H), 5.88, 5.82, 5.74 (3s, 1H each, CHPz), 4.57 (s, 1H, 4-H), 3.80 (s, 3H,1-CH3), 3.59 (s, 3H, 6-CH3), 2.46, 2.44, 2.40, 2.32, 2.20, 2.19 (6s, 3Heach, 6CH3Pz). 13C{1H} NMR (CDCl3): d ¼ 180.8 (C-2), 177.9 (C-7),163.6 (C-5),152.2,152.0,151.4 (3CqPz),151.0 (C-3),150.3 (C-9),144.6,144.4, 144.3 (3CqPz), 131.5, 131.2, 131.0, 123.0 (1JCeH ¼ 166.0 Hz, C-10eC-13), 128.7 (C-8), 127.5 (1JCeH ¼ 166.0 Hz, C-4), 108.6, 108.3,107.9 (1JCeH ¼ 176.1 Hz, 3CHPz), 52.7 (1JCeH ¼ 146.3), 51.2(1JCeH ¼ 147.6 Hz, CH3-6), 15.0, 13.6, 13.2, 13.0, 12.9, 12.6(1JCeH ¼ 128.4 Hz, 6CH3Pz). IR (KBr): n ¼ 3427 (H2O), 2925 (CH3),2534 (BH), 1714 (CO) cm�1. HR-MS (ESI-TOF) calcd for MHþ

(C28H36BN7O9Ir) 818.2291, found 818.2290.

6.8. TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(H2O)(OC(O)C6H4m-NO2)(2f)

In the same procedure mentioned above, compound 1 (50 mg;0.091 mmol), DMAD (11.2 mL; 0.091 mmol), m-nitrobenzoic acid(15.2 mg; 0.091 mmol) and CH2Cl2 (3 mL) were used to prepare

V. Salazar et al. / Journal of Organometallic Chemistry 696 (2011) 748e757 755

complex 2f. Yield: (solid, 56.1 mg, 75.0%). 1H NMR (CDCl3): d ¼ 8.76(t, 1H, 4JHeH ¼ 1.9 Hz, 9-H), 8.73 (br, s, 2H, H2O), 8.30 (ddd, 1H,3JHeH ¼ 8.0, 4JHeH ¼ 2.2, 1.1 Hz, 11-H), 8.27 (dd, 1H, 3JHeH ¼ 8.1,4JHeH ¼ 1.5 Hz, 13-H), 7.54 (t, 1 H, 3JHeH ¼ 8.1 Hz, 12-H), 5.90, 5.86,5.77 (3s, 1H each, 3CHpz), 4.62 (s, 1H, 4-H), 3.70 (s, 3H, 1-CH3),3.58 (s, 3H, 6-CH3), 2.50, 2.46, 2.42, 2.30, 2.24, 2.17 (6s, 3H each,6CH3Pz). 13C{1H} NMR (CDCl3): d ¼ 180.8 (C-2), 179.2 (C-7), 163.6(C-5), 152.2, 151.5, 151.3 (3CqPz), 151.3 (C-3), 148.3 (C-10), 144.7,144.6, 144.5 (3CqPz), 136.1 (C-8), 135.0 (1JCeH ¼ 165.2 Hz, C-13),129.2 (1JCeH ¼ 165.2 Hz, C-12), 127.2 (1JCeH ¼ 166.3 Hz, C-4), 126.3(1JCeH ¼ 177.1 Hz, C-11), 124.6 (1JCeH ¼ 170.6 Hz, C-9), 108.7,108.6, 108.0 (1JCeH ¼ 175.20 Hz, 3CHPz), 52.4 (1JCeH ¼ 146.8 Hz,CH3-1), 51.2 (CH3-6), 14.8, 13.7, 13.0, 12.9, 12.5 (in a 1:1:1.2:1ratio respectively) (1JCeH ¼ 129.2 Hz, 6CH3Pz). IR (KBr): n ¼ 3420(H2O), 2926 (CH3), 2531 (BH), 1715 (CO) cm�1. HR-MS (ESI-TOF)calcd for MHþ (C28H36BN7O9Ir) 818.2291, found 818.2291.

6.9. TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(H2O)(OC(O)C6H4oeCH3)(2g)

With the same general procedure, the complex 2g wasprepared by using compound 1 (50 mg; 0.091 mmol), DMAD(11.2 mL; 0.091 mmol), o-methylbenzoic acid (22.0 mg;0.091 mmol) and CH2Cl2 (3.0 mL). Yield: (solid, 70.0 mg, 97%). 1HNMR (CDCl3): d ¼ 9.13 (br, s, 2H, H2O); 7.82 (d, 1H,3JHeH ¼ 7.4 Hz, 13-H); 7.29 (t, 1H, 3JHeH ¼ 7.3 Hz, 12-H); 7.13 (d,H, 3JHeH ¼ 7.3 Hz, 10-H), 7.12 (t, 1H, 3JHeH ¼ 7.3 Hz, 11-H); 5.84,5.80, 5.75 (3s, 1H each, 3CHPz); 4.60 (s, 1H, 4-H); 3.83 (s, 3H, 1-CH3); 3.59 (s, 3H, 6-CH3); 2.49 (s, 3H, CH3oeCH3); 2.44, 2.41,2.25, 2.23, 2.21 (5s, in a 6:3:3:3:3 H ratio respectively, 6CH3Pz).13C{1H} NMR (CDCl3): d ¼ 183.6 (C-7); 180.7 (C-2); 163.4 (C-5);152.0 (C-3); 151.8, 151.2, 150.4, 144.2, 144.0, 143.9 (6CqPz); 138.6(C-8); 133.8 (C-9); 131.2 (1JCeH ¼ 158.4 Hz, C-10); 130.5(1JCeH ¼ 160.3 Hz, C-13); 125.2 (1JCeH ¼ 163.8 Hz, C-11,C-12);126.8 (1JCeH ¼ 166.2 Hz, C-4); 108.3, 108.0, 107.6(1JCeH ¼ 171.0 Hz, 3CHPz); 52.2 (1JCeH ¼ 146.9 Hz, CH3-1);50.9 (1JCeH ¼ 146.2 Hz, CH3-6); 21.4 (1JCeH ¼ 127.7 Hz,CH3oeCH3); 14.7, 13.5, 13.0, 12.6, 12.4 (in a 1:1:1:2:1 ratiorespectively) (1JCeH ¼ 130.0 Hz, 6CH3Pz). IR (KBr): n ¼ 3439(H2O), 2922 (CH3), 2533 (BH), 1692 (CO) cm�1. HR-MS (ESI-TOF)calcd for MHþ (C29H39BN6O7Ir) 787.2597, found.787.2600.

6.10. TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(H2O)(OC(O)C6H4peCH3)(2h)

Compound 1 (50 mg; 0.091 mmol), DMAD (11.2 mL;0.091 mmol), p-methylbenzoic acid (22.0 mg; 0.091 mmol) andCH2Cl2 (3.0 mL) were used to prepared complex 2h by employingthe above described general method. Yield: (solid, 65.0 mg,90.3%). 1H NMR (CDCl3): d ¼ 9.17 (br, s, 2H, H2O); 7.81(d, 2H,3JHeH ¼ 8.4 Hz, 9-H, 13-H); 7.13 (d, 2H, 3JHeH ¼ 8.4 Hz, 10-H, 12-H);5.85, 5.82, 5.74 (3s, 1H each, 3CHPz); 4.60 (s, 1H, 4-H); 3.71 (s, 3H,1-CH3); 3.58 (s, 3H, 6-CH3); 2.35 (s, 3H, 14-CH3); 2.47, 2.44, 2.40,2.25, 2.23, 2.17 (6s, 3H each, 6CH3Pz). 13C{1H} NMR (CDCl3):d ¼ 182.3 (C-7); 181.0 (C-2); 163.7 (C-5); 152.6 (C-3); 152.3, 151.5,144.4, 144.3, 144.2 (in a 1:2:1:1:1 ratio respectively) (6CqPz);142.1 (C-11); 131.6 (C-8); 129.5 (1JCeH ¼ 161.4 Hz, C-9, C-13);128.7 (1JCeH ¼ 158.4 Hz, C-10, C-12); 126.7 (1JCeH ¼ 166.1 Hz, C-4); 108.5, 108.4, 107.9 (1JCeH ¼ 175.3 Hz, 3CHPz); 52.4(1JCeH ¼ 146.1 Hz, CH3-1); 51.1 (1JCeH ¼ 146.1 Hz, CH3-6); 21.7(1JCeH ¼ 126.0 Hz, CH3peCH3); 14.7, 13.7, 13.0, 12.9, 12.8, 12.5(1JCeH ¼ 129.1 Hz, 6CH3Pz). IR (KBr): n ¼ 3407 (H2O), 2950 (CH3),2533 (BH), 1698 (CO) cm�1. HR-MS (ESI-TOF) calcd for MHþ

(C29H39BN6O7Ir) 787.2597, found 787.2597.

6.11. TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(H2O)(OC(O)Me) (3a)

Similarly, the product was obtained with using compound 1(50 mg; 0.091 mmol), DMAD (11.2 mL; 0.091 mmol), acetic acid(5.24 mL; 0.091 mmol) and CH2Cl2 (3.0 mL). Yield: 49.6 mg, 76.3% ofbeige solid. 1H NMR (CDCl3): d¼ 8.78 (br, s, 2H, H2O), 5.87, 5.80, 5.73(3s, 1H each, 3CHPz), 4.58 (s, 1H, 4-H), 3.93 (s, 3H, 1-CH3), 3.60(s, 3H, 6-CH3), 1.99 (s, 3H, 8-CH3), 2.43, 2.42, 2.38, 2.25, 2.22, 2.18(6s, 3H each, 6CH3Pz). 13C{1H} NMR (CDCl3): d ¼ 187.7 (C-7), 180.7(C-2), 163.7 (C-5), 152.4, 152.2, 151.3 (3CqPz), 151.3 (C-3), 144.4,144.3, 144.26 (3CqPz), 126.9 (1JCeH ¼ 166.1 Hz, C-4), 108.6, 108.4,107.9 (1JCeH ¼ 175.3 Hz, 3CHPz), 52.3 (1JCeH ¼ 146.9 Hz, CH3-1), 51.1(1JCeH ¼ 146.0 Hz, CH3-6), 24.2 (1JCeH ¼ 127.6 Hz, CH3-8), 14.4, 12.9,12.8, 12.78, 12.5 (in a 1:1:2:1:1 ratio respectively) (1JCeH¼ 124,6 Hz,6CH3Pz). IR (KBr): n ¼ 3419 (H2O), 2926 (CH3), 2529 (BH), 1713 (CO)cm�1. HR-MS (ESI-TOF) calcd for MHþ (C23H35BN6O7Ir) 711.2284,found 711.2286.

6.12. TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(NC6H5)(OC(O)C6H5) (4a)

The solution of compound 2a (50 mg; 0.065 mmol) dissolved inpyridine (1.0 mL; 12.4 mmol) was stirred at 60 �C for 12 h. Thevolatiles were removed in vacuum, and the quantitative conversioninto 4a was verified by 1H NMR spectroscopy. The obtainedcompound was crystallized from hexane at �20 �C, Yield: (solid,48.0 mg, 89%). 1H NMR (CDCl3): d ¼ 9.20 (d, 1H, 3JHeH ¼ 5.5 Hz,14-H), 8.02 (d, 2H, 3JHeH ¼ 7.7 Hz, 9-H, 13-H), 7.65 (t, 1H,3JHeH ¼ 7.3 Hz, 16-H), 7.50 (d, 1H, 3JHeH ¼ 5.4 Hz, 18-H), 7.36 (t,1H, 3JHeH ¼ 6.2 Hz, 17-H), 7.27 (m, 3H, 10-He12-H), 6.91 (t, 1H,3JHeH ¼ 6.6 Hz, 15-H), 5.76, 5.63, 5.56 (3s, 1H each, CHPz), 4.52 (s,1H, 4-H), 3.88 (s, 3H, 1-CH3), 3.46 (s, 3H, 6-CH3), 2.44, 2.38, 2.36,1.93,1.54, 0.83 (6s, 3H each, 6CH3Pz). 13C{1H} NMR (CDCl3): d¼ 177.9(C-2), 171.7 (C-7), 164.0 (C-5), 155.8 (C-3), 154.0 (1JCeH ¼ 178.4 Hz,C-18), 153.5 (1JCeH¼ 182.20 Hz, C-14), 152.7, 151.2, 151.1, 144.6, 143.2(in a 1:1:1:1:2 ratio respectively) (6CqPz), 137.7 (1JCeH ¼ 159.1 Hz,C-16), 135.8 (C-8), 130.0 (1JCeH ¼ 159.1 Hz, C-10), 129.7(1JCeH ¼ 162.20 Hz, C-9, C-13), 127.6 (1JCeH ¼ 158.4 Hz, C-11,C-12),127.2 (1JCeH ¼ 166.3 Hz, C-4), 124.5 (1JCeH ¼ 166.8 Hz, C-15), 123.9(1JCeH ¼ 169.9 Hz, C-17), 108.3, 107.5, 107.2 (1JCeH ¼ 173.8 Hz,3CHPz), 51.0 (1JCeH ¼ 146.1 Hz, CH3-6), 50.9 (1JCeH ¼ 146.1 Hz,CH3-1), 15.3, 14.7, 13.0, 12.7, 10.9 (in a 1:1:2:1:1 ratio respectively)(1JCeH ¼ 128.4 Hz, 6CH3Pz). IR (KBr): n ¼ 3447 (H2O), 2927 (CH3),2532 (BH), 1703 (CO) cm�1. The compound shows decompositionduring mass spectrometric experiments.

6.13. TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(NC5H4m-Br)(OC(O)C6H5)(4b)

A solution of compound 2a (25 mg; 0.033 mmol) in CH2Cl2(3.0 mL) and m-Brepyridine (10.0 ml; 0.098 mmol) was stirred at60 �C for 5 h. After the reaction was completed, volatiles wereremoved in vacuum and the quantitative conversion into 4b wasverified by 1H NMR spectroscopy. 4b0:4b00 in a 80:20 ratio. Majorisomer 4b0: 1H NMR (CDCl3): d ¼ 9.47 (d, 1H, 4JHeH ¼ 2.0 Hz, 14-H),9.29 (d, 1H, 3JHeH ¼ 5.6 Hz, 18-H), 8.10 (m, 2H, 9-H, 13-H), 7.88 (dm,1H, 3JHeH ¼ 8.4 Hz, 16-H), 7.57 (d, 1H, 3JHeH ¼ 5.6 Hz, 11-H), 7.35(m, 2H, 10-H, 12-H), 6.88 (dd, 1H, 3JHeH ¼ 8.0, 5.6 Hz, 17-H), 5.83,5.72, 5.63 (3s, 1H each, CHPz), 4.57 (s, 1H, 4-H), 4.06 (s, 3H, 1-CH3),3.54 (s, 3H, 6-CH3), 2.51, 2.45, 2.42, 2.00, 1.63, 0.95 (6s, 3H each,6CH3Pz). 13C{1H} NMR (CDCl3): d ¼ 177.2 (C-2), 171.2 (C-7), 163.7(C-5), 154.8 (C-3), 154.7 (1JCeH ¼ 193.9 Hz, C-14), 152.0(1JCeH ¼ 162.0 Hz, C-18), 152.5, 150.7, 150.6, 144.4, 143.1, 143.0(6CqPz), 140.0 (1JCeH ¼ 171.0 Hz, C-16), 135.1 (C-8), 129.9(1JCeH ¼ 158.1 Hz, C-11), 129.3 (1JCeH ¼ 160.9 Hz, C-9, C-13), 127.4(1JCeH ¼ 158.7 Hz, C-10, C-12), 126.9 (1JCeH ¼ 165.7 Hz, C-4), 124.7

V. Salazar et al. / Journal of Organometallic Chemistry 696 (2011) 748e757756

(1JCeH ¼ 169.0 Hz, C-17), 119.1 (C-15), 108.1, 107.3, 107.1(1JCeH ¼ 174.7 Hz, 3CHPz), 51.1 (1JCeH ¼ 145.5 Hz, CH3-6), 50.7(1JCeH ¼ 145.3 Hz, CH3-1), 15.0, 14.5, 12.7, 12.4, 10.7 (in a 1:1:2:1:1ratio respectively) (1JCeH ¼ 128.7 Hz, 6CH3Pz). Minor isomer 4b00: 1HNMR (CDCl3): d ¼ 8.68 (s, 1H, 4JHeH ¼ 1.6 Hz, 14-H), 8.53 (d,1H, 3JHeH ¼ 3.6 Hz, 18-H), 8.09 (m, 2H, 9-H, 13-H), 7.82 (dm, 1H,3JHeH ¼ 8.4 Hz, 16-H), 7.35 (m, 3H, 11-H, 12-H), 7.20 (dd, 1H,3JHeH ¼ 8.0, 4.8 Hz, 17-H), 5.87, 5.70, 5.66 (3s, 1H each, CHPz), 4.56(s, 1H, 4-H), 3.95 (s, 3H, 1-CH3), 3.54 (s, 3H, 6-CH3), 2.53, 2.45, 1.99,1.65, 0.98 (5s, in a 3:6:3:3:3 H ratio respectively, 6CH3Pz). 13C{1H}NMR (CDCl3): d ¼ 177.5 (C-2), 171.3 (C-7), 163.7 (C-5), 154.7 (C-3),154.3 (1JCeH ¼ 190.0 Hz, C-14), 151.8 (1JCeH ¼ 164.5 Hz, C-18), 152.4,150.5, 150.6, 144.7, 143.2, 143.0 (6CqPz), 140.2 (1JCeH ¼ 170.9 Hz,C-16), 135.4 (C-8), 128.1 (1JCeH ¼ 160.4 Hz, C-11), 129.3(1JCeH ¼ 160.9 Hz, C-9, C-13), 126.9 (1JCeH ¼ 165.0 Hz, C-10, C-12),127.0 (1JCeH ¼ 165.6 Hz, C-4), 124.2 (1JCeH ¼ 168.5 Hz, C-17), 119.4(C-15), 108.2, 107.3, 107.2 (1JCeH ¼ 173.4 Hz, 3CHPz), 50.8(1JCeH ¼ 145.4 Hz, CH3-6), 50.7 (1JCeH ¼ 145.3 Hz, CH3-1), 14.8, 14.4,12.8, 12.7, 12.5, 10.9 (1JCeH ¼ 128.4 Hz, 6CH3Pz). Anal. forC33H38N7BO6BrIr$0.1CH2Cl2 (Mw ¼ 920.13448): calcd: C, 43.21; H,4.18; N, 10.66 Expt.: C, 42.33; H, 4.16; N, 9.89.

6.14. TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(NC5H4m-Cl)(OC(O)C6H5)(4c)

A solution of compound 2a (25 mg, 0.033 mmol) in CH2Cl2(3.0 mL) and m-Clepyridine (9 ml, 0.096 mmol) was stirred at 60 �Cfor 5.0 h and then volatiles were removed under reduced pressure.The quantitative conversion into 6c was confirmed by 1H NMRspectroscopy. 4c0:4c00 in a 76:24 ratio. Major Isomer 4c0: 1H NMR(CDCl3): d ¼ 9.36 (d, 1H, 4JHeH ¼ 2.4 Hz, 14-H), 9.25 (d, 1H,

Table 2Crystal data for complexes 2d, 2h and 4a.

Compound 2d

Empirical formula C33 H47 B Cl Ir N6 O7

Formula weight 878.23Crystal colour and shape Yellow prismCrystal size (mm3) 0.3 � 0.2 � 0.1Crystal system MonoclinicSpace group P2(1)/c

Unit cell dimensionsa, �A 12.6199(10)b, �A 19.0261(15)c, �A 16.7046(13)a, deg 90b, deg 100.142(2)g, deg 90V, �A3 3765.6(5)Z 4Dcalcd, Mg m�3 1.549m, mm�1 3.669Diffractometer Bruker SMART 5000 CCDRadiation and wavelength l(Mo Ka), 0.71073 �Amonochromator GraphiteScan type u

2q range for collection, (�) 4.04 to 52.04T (K) 293(2)Index ranges �15 � h � 13; �23 � k � 23;

�20 � l � 20Reflections collected 24420Independent reflections 7395 (Rint ¼ 0.0320)Observed reflections 5787 (F > 4s(F))Parameters/restraints 450/0R final; R all data 0.0334, 0.0498Rw final, Rw all dataa 0.0851, 0.0929GOF (all data) 1.092Max, min peaks (e �A�3) 1.267, �0.812

a w�1 ¼ s2ðF2o Þ þ ðPÞ2 þ P where P ¼ ðF2o þ 2F2c Þ=3.

3JHeH ¼ 5.6 Hz, 18-H), 8.12 (m, 2H, 9-H, 13-H), 7.75 (dm, 1H,3JHeH ¼ 8.8 Hz, 16-H), 7.54 (d, 1H, 3JHeH ¼ 6.0 Hz, 11-H), 7.41 (dd,1H, 3JHeH ¼ 13.6, 8.0 Hz, 10-H), 7.37 (m, 1H, 12-H), 6.94 (dd, 1H,3JHeH ¼ 8.4, 6.0, 17-H), 5.84, 5.73, 5.64 (3s, 1H each, CHPz), 4.59(s, 1H, 4-H), 4.05 (s, 3H, 1-CH3), 3.55 (s, 3H, 6-CH3), 2.52, 2.46, 2.44,2.02, 1.63, 0.96 (6s, 3H each, 6CH3Pz). 13C{1H} NMR (CDCl3):d ¼ 174.6 (C-2), 168.8 (C-7), 161.5 (C-5), 152.8 (C-3), 150.7(1JCeH ¼ 186.6 Hz, C-14), 149.7 (1JCeH ¼ 184.0 Hz, C-18), 150.5, 148.8,148.7, 142.7, 141.4, 141.3 (6CqPz), 135.7 (1JCeH ¼ 166.3 Hz, C-16),133.6 (C-8), 129.9 (C-15), 128.5 (1JCeH ¼ 154.4 Hz, C-11), 127.9(1JCeH ¼ 156.9 Hz, C-9, C-13), 126.1 (1JCeH ¼ 155.4 Hz, C-10, C-12),125.6 (1JCeH ¼ 160.7 Hz, C-4), 123.2 (1JCeH ¼ 164.3 Hz, C-17), 107.2,106.5, 106.3 (1JCeH ¼ 173.4 Hz, 3CHPz), 51.6 (1JCeH ¼ 146.4 Hz, CH3-6), 51.3 (1JCeH ¼ 145.9 Hz, CH3-1), 16.5, 16.1, 14.4, 14.0, 12.4 (ina 1:1:2:1:1 ratio respectively) (1JCeH ¼ 128.3 Hz, 6CH3Pz). Minorisomer 4c00: 1H NMR (CDCl3): d ¼ 8.58 (d, 1H, 4JHeH ¼ 2.0 Hz, 14-H),8.49 (dd, 1H, 3JHeH ¼ 4.8, 4JHeH ¼ 1.2 Hz, 18-H), 8.10 (m, 2H, 9-H,13-H), 7.67 (dm, 1H, 3JHeH ¼ 8.4 Hz, 16-H), 7.37 (m, 3H, 10-H, 11-H,12-H), 7.27 (dd, 1H, 3JHeH ¼ 13.2, 5.6 Hz, 17-H), 5.88, 5.71, 5.67 (3s,1H each, CHPz), 4.58 (s, 1H, 4-H), 3.96 (s, 3H, 1-CH3), 3.55 (s, 3H,6-CH3), 2.54, 2.46, 2.01, 1.66, 0.99 (5s, in a 3:6:3:3:3 H, 6CH3Pz). 13C{1H} NMR (CDCl3): d ¼ 174.9 (C-2), 168.9 (C-7), 161.5 (C-5), 152.8(C-3), 150.5 (1JCeH ¼ 183.2.0 Hz, C-14), 149.5 (1JCeH ¼ 184.0 Hz, C-18), 150.3, 148.8, 148.6, 142.9, 141.5, 141.3 (6CqPz), 135.8(1JCeH ¼ 166.2 Hz, C-16), 133.9 (C-8), 130.3 (C-15), 126.7(1JCeH ¼ 156.1 Hz, C-11), 127.9 (1JCeH ¼ 156.9 Hz, C-9, C-13), 125.1(1JCeH ¼ 155.4 Hz, C-10, C-12), 125.7 (1JCeH ¼ 160.7 Hz, C-4), 122.7(1JCeH ¼ 164.2 Hz, C-17), 107.4, 106.5, 106.4 (1JCeH ¼ 174.8 Hz,3CHPz), 51.4 (1JCeH ¼ 146.3 Hz, CH3-6), 51.3 (1JCeH ¼ 145.9 Hz, CH3-1), 16.4, 16.0, 14.5, 14.1, 12.6 (in a 1:1:2:1:1 ratio respectively)(1JCeH ¼ 127.2 Hz, 6CH3Pz). Anal. for C33H38N7BO6ClIr$0.5CH2Cl2

2h 4a

C34 H50 B Ir N6 O7 C34 H41 B Cl2 Ir N7 O6

857.81 917.65Yellow plate Brown prism0.25 � 0.10 � 0.03 0.31 � 0.26 � 0.17Monoclinic MonoclinicP2(1)/c P2(1)/n

19.1007(7) 16.8898(4)11.4057(5) 20.4438(6)19.8527(9) 22.0843(7)90 90116.907(2) 103.1530(1)90 903856.8(3) 7425.5(4)4 81.477 1.6423.513 3.794EnrafeNonius Kappa CCD Bruker SMART 5000 CCDl(Mo Ka), 0.71073 �A l(Mo Ka), 0.71073 �Agraphite Graphiteu � f U5.36 to 55.02 2.74e46.52�

293(2) 293(2) K�24 � h � 18; �14 � k � 13;�23 � l � 25

�13 � h � 18, �22 � k � 22,�24 � l � 24

18038 711827808 (Rint ¼ 0.0435) 10489 (Rint ¼ 0.0677)4942 (F > 4s(F)) 8423 (F > 4s(F))509/89 975/00.0489, 0.1005 0.0324, 0.04720.0769, 0.0897 0.0730, 0.07811.037 1.0391.392, �0.654 1.696, �0.964

V. Salazar et al. / Journal of Organometallic Chemistry 696 (2011) 748e757 757

(Mw ¼ 909.6566): calcd: C, 44.23; H, 4.32; N, 10.78 Expt.: C, 44.09;H, 4.28; N, 9.94.

6.15 TpMe2Ir(E-C(CO2Me)]CH(CO2Me))(OC(O)C6H5)(NCMe) (5)

A solution of compound 2a (50 mg, 0.065 mmol) in acetonitrile(3.0 mL, 54 mmol) was stirred at 60 �C for 12 h. After the reactionwas completed, volatileswere removed in vacuum. The quantitativeconversion into 5 was established by 1H NMR spectroscopy.The compound obtained was crystallized from hexane at �20 �C,Yield (solid, 50.5 mg, 98%). 1H NMR (CDCl3): d ¼ 7.87 (d, 2H,3JHeH¼ 7.30Hz, 9-H,13-H); 7.33 (t,1H, 3JHeH¼ 7.40Hz,11-H); 7.26 (t,2H, 3JHeH ¼ 6.60 Hz, 10-H, 12-H); 5.82, 5.80, 5.78 (3s, 1H each,3CHPz); 4.64 (s,1H, 4-H); 3.80 (s, 3H,1-CH3); 3.57 (s, 3H, 6-CH3); 2.74(s, 3H, 14-CH3); 2.44, 2.41, 2.29, 2.20, 2.12 (5s, in a 6:3:3:3:3 H ratiorespectively, 6CH3Pz).13C{1H} NMR (CDCl3): d¼ 177.8 (C-2); 173.2 (C-7); 163.7 (C-5); 152.3 (C-3); 152.0, 151.7, 151.0, 144.2, 143.8, 143.5(6CqPz); 135.6 (C-8); 129.8 (C-11); 129.3 (C-9, C-13); 127.3 (C-10, C-12); 125.8 (C-4); 117.7 (C-15); 108.0, 106.9 (in a 2:1 ratio respec-tively) (3CHPz); 51.7 (CH3-1); 50.8 (CH3-6); 14.8,14.5,12.9,12.8,12.7,12.3 (6CH3Pz); 3.8 (CH3-14). IR (KBr): n ¼ 2924 (CH3); 2519 (BH);2237 (CN); 1710 (CO) cm�1. HR-MS (ESI-TOF) calcd for MHþ

(C30H38BN7O6Ir) 796.2600, found 796.2604.

7. Computational procedure

Calculations were carried out by using Amsterdam DensityFunctional (ADF) code [22]. The geometry optimizationwasworkedout using the LDA [23], PW91 [24] and PBE [25] exchange-corre-lation (XC) functional. The triple z þ polarization (TZP) basis ofSlater-type orbitals provided with the ADF package was used for allatoms. Full optimization geometry was performed for compound4b using the X-ray structure data of compound 4a and thena rotational barrier analysis for the optimized geometry by rotatingthe pyridine ring in the counterclockwise up to 360� through a step20� around the IreN bond and the dihedral angle (OeIreNPyeCPy)was used as starting point to generate the rotamers; in each step,all structures being fully optimized and they were checked byvibrational frequency analysis.

8. X-ray structure determination

Details for data collection structure refinement for 2d, 2h and 4aare presented in Table 2. The crystals (2d, and 4a) were mountedon glass fibers and the crystal 2h was mounted in MicroMounts(MitGen company, www.mitegen.com). For 2h (as solvated2h$C5H12), data were collected using a EnrafeNonius Kappa CCDReflections and data for 2d (as solvated 2d$C5H12) and 4a (assolvated 4a$CH2Cl2) were collected on a Bruker SMART 5000 CCD-based diffractometer. For all compounds, all non-hydrogen atomswere refined anisotropically. Hydrogen atoms were fixed at ideal-ized refined positions. Data collection and the determination of celldimensions for all compounds were carried out using the collectsoftware [26] and HKL Scalepack [27] The frames were integratedwith the SAINT software package [28] using a narrow-frame algo-rithm. A semi-empirical absorption correction method (SADABS)[29] was applied in all cases. All structures were resolved by directmethods, completed by subsequent difference Fourier synthesis,and refined by full-matrix least-squares procedures using theSHELX-97 package [29].

Acknowledgments

Authors acknowledge the projects Consejo Nacional de Cienciay Tecnología (CONACYT, Mexico, Grant No.: 025424, J110.380,I32816 and 84453), “Ricardo J. Zevada” Foundation, and the bilat-eral assistance CSIC (Sevilla, Spain)-CONACYT-UAEH (México) forthe financial support. Additionally, Universidad Autónoma delEstado de Hidalgo (UAEH) Project No. DIP-ICBI-AAQ-056 is grate-fully acknowledged. J. Cruz appreciates to Programa de Mejor-amiento del Profesorado (PROMEP)-UAEH for the additionalfinancial support (Grant No 103.5/08/5390). RMP, MH and AE thankCONACYT for their scholarships.

Appendix A. Supplementary information

CCDC 768172, 768174 and 768173 contain the supplementarycrystallographic data for 2d, 2h and 4a. These data can be obtainedfree of charge from The Cambridge Crystallographic Data Centrevia www.ccdc.cam.ac.uk/data_request/cif. Also, all NMR spectraincluding 1-D, 2-D heteronuclear experiments and long range bondcorrelations are available for this article from the author.

Appendix A. Supplementary information

Supplementary information associated with this article can befound in the online version at doi:10.1016/j.jorganchem.2010.09.073.

References

[1] D. Austruc, Organometallic Chemistry and Catalysis. Springer-Verlag, BerlinHeidelberg New York, 2007, (Chapter 6). pp. 140e142.

[2] Ch. S. Chin, G. Won, D. Chong, M. Kim, H. Lee, Acc. Chem. Res. 35 (2002) 218.[3] S. Trofimenko, Scorpionates-The Coordination Chemistry of Poly-

pyrazolylborate Ligands. Imperial College Press, London, 1999, p. 282.[4] S. Trofimenko, Chem. Rev. 93 (1993) 943.[5] G. Parkin, Adv. Inorg. Chem. 42 (1995) 291.[6] P.K. Byers, A.J. Canty, R.T. Honeyman, Adv. Organomet. Chem. 34 (1992) 1.[7] C. Slugovc, I. Padilla-Martinez, S. Sirol, E. Carmona, Coord. Chem. Rev. 213

(2001) 129.[8] Y. Alvarado, O. Boutry, E. Gutierrez, A. Monge, M.C. Nicasio, M.L. Poveda,

P.J. Pérez, C. Ruiz, C. Bianchini, E. Carmona, Chem. Eur. J. 3 (1997) 860.[9] M. Paneque, C.M. Posadas, M.L. Poveda, Nuria Rendón, K. Mereiter, Organo-

metallics 26 (2007) 3120.[10] E. Gutiérrez-Puebla, A. Monge, M.C. Nicasio, P.J. Pérez, M.L. Poveda, L. Rey,

C. Ruíz, E. Carmona, Inorg. Chem. 37 (1998) 4538.[11] J.M. O0Connor, A. Closson, P. Gantzel, J. Am. Chem. Soc. 124 (2002) 2434.[12] W.H. Baddley, M.A. Fraser, J. Am. Chem. Soc. 91 (1969) 3661.[13] K.R. Reddy, K. Surekha, G.-H. Lee, S.-M. Peng, S.-T. Liu, Organometallics 20

(2001) 5557.[14] T. Yagyu, K. Osakada, M. Brookhart, Organometallics 19 (2000) 2125.[15] E. Hevia, J. Pérez, L. Riera, V. Riera, D. Miguel, Organometallics 21 (2002) 1750.[16] L. Cuesta, E. Hevia, D. Morales, J. Pérez, V. Riera, M. Seitz, D. Miguel, Organ-

ometallics 24 (2005) 1772.[17] M. Paneque, C.M. Posadas, M.L. Poveda, N. Rendón, E. Alvarez, K. Mereiter,

Chem. Eur. J. 13 (2007) 5160.[18] D.M. Tellers, S.J. Skoog, R.G. Bergman, T.B. Gunnoe, W.D. Harman, Organo-

metallics 19 (2000) 2428.[19] M. Paneque, M.L. Poveda, V. Salazar, E. Gutierrez-Puebla, A. Monge, Organo-

metallics 19 (2000) 3120.[20] A. Bondi, J. Phys. Chem. 68 (1964) 441.[21] B. Cordero, V. Gómez, A.E. Platero-Prats, M. Revés, J. Echeverría, E. Cremades,

F. Barragán, S. Alvarez, Dalton Trans. (2008) 2832.[22] ADF: Amsterdam density functional, scientific computing and modelling

(SCM), Theoretical Chemistry, Vrije Universiteit, Amsterdam. The Netherlands.[23] S.H. Vosko, L. Wilk, M. Nusair, Can. J. Phys. 58 (1980) 1200.[24] J.P. Perdew, J.A. Chevary, S.H. Vosko, K.A. Jackson, M.R. Pederson, D.J. Sing,

C. Fiolhais, Phys. Rev. B. 46 (1992) 6671.[25] J.P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett. 77 (1996) 3865.[26] Nonius, COLLECT. Nonius BV, Delft, The Netherlands, 2001.[27] Z. Otwinowski, W. Minor, Methods in Enzymology. Academic Press, New York,

1997, p. 307.[28] Bruker programs: SMART. Version 5.629. SAINTþ.[29] G.M. Sheldrick, Acta. Crystallogr. A64 (2008) 112.