Cryst. Res. Technol. 44, No. 6, 669 – 674 (2009) / DOI 10.1002/crat.200800552

© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Solvothermal syntheses and crystal structures of two

4-heterocyclic acylpyrazolone complexes

Jingqi Li, Jinzhou Li*, Hengqiang Zhang, and Jing Li

Department of Chemistry, Harbin Normal University, Harbin 150025, P. R. China

Received 18 November 2008, revised 23 February 2009, accepted 27 February 2009 Published online 10 March 2009

Key words acylpyrazolone complex, solvothermal synthesis, crystal structure. PACS 61.66.Hq

Many explorations of transition metal (M)-L system under solvothermal condition, have led to the syntheses of two new 4-heterocyclic acylpyrazolone complexes [Co(L)2(CH3OH)2] (HL = 1-phenyl-3-methyl-4-(2-furoyl)-5-pyrazolone) (1) and [Cr(L)3] (2). Single-crystal X-ray analyses reveal that crystal structures of compound 1 and 2 are respectively orthorhombic, Pbca, a = 15.0378(6) Å, b = 9.8405(4) Å, c = 20.7321(8) Å, V = 3067.9(2) Å3, Z = 8 and triclinic, P-1, a = 10.7966(18) Å, b = 13.023(2) Å, c = 15.520(3) Å, α = 73.011(4)°, β = 84.884(4)°, γ = 70.267(4)°, V = 1964.3(6) Å3, Z = 2. Complex 1 has a two-dimensional (2D) network structure that is formed by O–H···N H-bonding interactions. Complex 2 makes a one-dimensional (1D) zigzag chain structure by intermolecular π···π interactions, which is further interlinked via C–H···N H-bonding interactions to generate a 2D sheet, and then a three-dimensional (3D) supramolecular network structure is further linked by intermolecular C–H···π interactions.

© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

1 Introduction

Acylpyrazolones are an interesting class of β-diketone compounds which are widely used as solvent extractions of metal ions, laser working materials and NMR shift-reagents [1-3]. Their metal complexs have been found to display catalytic performance, biological activity and enhanced luminescence. We've done some research works on a heterocyclic acylpyrazolone and its complexes, which both possess antibacterial activity and analgesic activity [4-5]. In general, the single crystals of acylpyrazolones and their complexes are easily obtained under routine conditions. But as we all know, the crystal structures about acylpyrazolone complexes of chromium (Ш) have never been reported before [6]. So we attempt to use solvothermal method to synthesize the complexes and get their single crystals. The solvo(hydro)thermal synthesis has rapidly developed over the past several years due to its effectiveness, simplicity and environmental friendliness [7]. In our previous work, series 4-heterocyclic acylpyrazolone derivatives and some transition metal complexes have been reported [8-10]. In this paper, as a continuation of our research, we report syntheses by solvothermal method in a special mixed solvent system and crystal structures about two 4-heterocyclic acylpyrazolone complexes: [Co(L)2(CH3OH)2] (1) and [Cr(L)3] (2).

2 Experimental

Materials and physical measurements All reagents in the syntheses were analytical grade. Elemental analyses for carbon, hydrogen and nitrogen were performed on Thermo-Fiash EA1112 elemental analyzer. The

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* Corresponding author: e-mail: lijinzhou20@163.com

670 Jingqi Li et al.: Two 4-heterocyclic acylpyrazolone complexes

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infrared spectra (4000 ~ 600 cm−1) were recorded by using KBr pellet on a Nicolet-Avatar 370 FTIR spectrometer.

Synthesis of complex 1 HL was synthesized according to the method proposed by Jensen (1959) [11]. A solution of Co(CH3COO)2·4H2O (0.1 mmol, 25 mg) in 5 mL of methanol was added to a solution of HL (0.2 mmol, 53 mg) in 5 mL ethanol solution. The mixture was placed in a 20-mL Teflon-lined stainless steel vessel with addition of a few drops of glacial acetic acid as a catalyst, heated to 120 °C for 3 days, and then cooled to room temperature over 12 h. Yellow crystals of 1 were obtained. Anal. (%) calcd for C32H30CoN4O8: C, 58.45; H, 4.60; N, 8.52. Found: C, 58.41; H, 4.58; N, 8.49. IR (KBr, cm–1): IR (KBr, cm–1) 3440(w), 1560(s), 1491(s), 1462(s), 1437(m), 1413(w), 1376(w), 1356(w), 1238(w), 1229(w), 489(m).

Synthesis of complex 2 A solution of CrCl·6H2O (0.1 mmol, 27mg) in 5 mL of methanol was added to a solution of HL (0.3 mmol, 81mg) in 5 mL of ethanol. The mixture was placed in a 20-mL Teflon-lined stainless steel vessel with addition of a few drops of glacial acetic acid as a catalyst, heated to 115 °C for 3 days, and then cooled to room temperature over 12 h. Green crystals of 2 were obtained. Anal. (%) calcd for C45 H33CrN6O9 (%): C, 63.31; H, 3.90; N, 9.84. Found: C, 63.26; H, 3.85; N, 9.79. IR (KBr, cm–1): IR (KBr, cm–1) 3444(w), 1560(s), 1492(s), 1462(s), 1442(m), 1429(w), 1376(w), 1358(w), 1301(w), 493(m).

Crystallographic data collection and structures determination All measurements were made on a Bruker SMART CCD single-crystal diffractometer with MoKα radiation (0.71073Å) by using φ and ω scans technique at room temperature. SMART software was used for data collection and cell refinement and the program SAINT for data reduction including correction for decay of intensity [12]. The structures were solved by direct methods with SHELXS-97, and a full-matrix least-squares refinement on F2 was carried out using SHELXL-97 [13]. The hydrogen atoms were observed in a difference Fourier but placed geometrically and treated as riding on their parent atoms except H atoms of OH. Table 1 shows crystallographic crystal data of the complexes 1 and 2. Selected bond lengths and angles are listed in table 2.

Table 1 Crystallographic data for 1 and 2. Crystallographic Data Center as supplementary publication number CCDC-691931 and 697509. Cambridge Crystallographic Data Center, 12 Union Road, Cambridge, CB2 1EZ, UK; E-mail: deposit@ccdc.cam.ac.uk.

Empirical formula C32H30CoN4O8 C45 H33CrN6O9

Formula weight 657.53 853.77

Temperature (K) 295(2) 295(2)

Wavelength (Å) 0.71073 0.71073

Crystal system Orthorhombic Triclinic

Space group Pbca P-1

Unit cell dimensions a=15.0378(6) Å, b=9.8405(4) Å,

c=20.7321(8) Å

a=10.7966(18) Å, b=13.023(2) Å, c=15.520(3) Å, α=73.011(4)°, β=84.884(4)°,γ=70.267(4)°

Volume, Z 3067.9(2) Å3, 8 1964.3(6)Å3,2

Calculated density (Kg/m3) 1.424 1.444

Crystal size (mm3) 0.26×0.20×0.17 0.15×0.13×0.10

θ Range for data collection (º)

1.96-28.28 1.37-26.00

Reflections collected 17872 10904

Independent reflection 3760 [Rint=0.0583] 7626 [Rint=0.0289]

R indices (all data) R1 = 0.0682, wR2 = 0.1195 R1 = 0.2039, wR2 = 0.1888

3 Results and discussion

[Co(L)2(CH3OH)2] (1) Crystallographic data show that symmetry-expanded structure of complex 1 is composed of two deprotonated HL molecules, two methanol molecules and one Co(II) atom (Fig. 1). The Co(II) atom, located on an inversion centre, assumes a nearly perfect octahedral CoO6 coordination geometry with the Co–O–Co bond angles are ranging from 87.36(6) to 92.64(6)° (Table 2). The two methanol molecules are mutually trans, while the two bidentate HL ligands adopt a deprotonated enol form in chelating to the

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Co(II) centre via their O atoms with the Co–O bond distances fall in the range of 1.9979(14) to 2.1508(16) Å which is slightly shorter than the previously reported [14]. We have presented in another similarly report a coordination sphere involving the pyrazolonato moiety and trans axial ethanol groups around a metal ion centre [15]. In complex 1, chelate ring has a boat configuration and deviations of atoms Co(1) and O(2) from the plane are 0.2563 Å and 0.2348 Å respectively. The dihedral angle formed by the chelate ring and the mean pyrazolone ring plane is 15.10°. Due to the steric hindrance, the dihedral angles of the pyrazolone ring plane with phenyl ring planes and the furan ring are 15.28° and 14.20° respectively. As a result, the whole compound is not a planar molecule.

Fig. 1 ORTEP plot of the symmetry-expanded structure in complex 1, showing the coordination environment of the Co(II) atom with 30% probability ellipsoids.

Fig. 2 A view of the 2D network sheet of complex 1 formed by H-bonding interactions (red dashed lines). Hydrogen atoms other than those participating in hydrogen bonding are omitted for clarity. (Online color at www.crt-journal.org)

The structure of complex 1 consists of 2D network sheet connected by intermolecular O–H···N H-bonding interactions [16] (Fig. 2) and there are two C–H···O weak H-bonding interactions observed (Table 3). In addition, C–H···π interactions also have been found in complex 1 (Table 4). In above, H-bonding interactions play an important role in forming the supramolecular structure by self-assembly and stabilizing.

Specially, the single crystals were synthesized in the mixed solvents of methanol with ethanol. As a result, two methanol molecules take part in coordination. We conclude that the coordination of methanol is due to its small size compare to ethanol.

[Cr(L)3] (2) Crystallographic data reveals that a Cr(Ш) atom is octahedrally coordinated by three deprotonated HL molecules (Fig. 3). The three bidentate HL ligands adopt a deprotonated enol form in chelating to the Cr(Ш) centre via their O atoms with the Cr–O bond distances falling in the range of 1.939(4) to 1.979(4) Å which are similar to those found in other transition-metal complexes of acylpyrazolone [17] (Table 2). The three ligands just define the meridional geometric isomer. Compared with the complex 1, the ionic radius (75.5 pm) of Cr(Ш) is smaller than Co(II)’s (83.8 pm). Thus, it was thought that Cr(Ш) has higher charge density and forms easily the structure coordinated by three bidentate HL. The arrangement of the ligands around the central Cr(Ш) atom indicates a slight distortion from idealized octahedral geometry with the Cr–O–Cr bond angles ranging from 87.23(17) to 92.29(16)°. The O(2), O(3), O(4) and O(6) atoms deviate (±0.01 Å) from their least–squares plane, so they almost lie in one plane. As shown in Table 2, the C–O bond lengths (1.290–1.318 Å) in each chelate ring are intermediate between the single C–O, 1.43 Å and double C=O, 1.22 Å bonds in the enol-form L ligand, indicating some delocalization about the chelate ring [18].

In complex 2, there are two pairs of different intermolecular face to face π···π interactions between the adjacent molecules. They all formed between the pyrazolone rings and the furan rings. And the details of π···π interactions for complex 2 are given in table 5. Due to these π···π interactions, complex 2 has a 1D infinite zigzag chain structure (Fig. 4). As far as we known, such 1D structure is still rare in the systems of Metal-

672 Jingqi Li et al.: Two 4-heterocyclic acylpyrazolone complexes

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organic complexes [19]. Furthermore, the C–H···N H-bonding interactions link the 1D zigzag chain motifs into the 2D sheets.

Fig. 3 ORTEP plot of the complex 2, showing the coordination environment of the Cr(Ш) atom with 30% probability ellipsoids.

Fig. 4 The 1D zigzag chain of complex 2 formed by two pairs of different intermolecular face-to-face π···π interactions (red dashed lines) between furan rings and pyrazolone rings. Hydrogen atoms are omitted for clarity. (Online color at www.crt-journal.org)

Table 2 Selected bond lengths and angles for 1 and 2 [Å and o]. (Symmetry transformations used to generate equivalent atoms: (1) # 1 -x,-y,-z+1).

1 Co(1)–O(1) 1.9979(14) O(1)#1–Co(1)–O(4)#1 88.95(7) Co(1)–O(2) 2.0709(13) O(1)–Co(1)–O(4)#1 91.05(7) Co(1)–O(4) 2.1508(16) O(2)–Co(1)–O(4)#1 88.88(6)

O(1)#1–Co(1)–O(2) 87.36(6) O(2)–Co(1)–O(4) 91.12(6) O(1)–Co(1)–O(2) 92.64(6) O(1)#1–Co(1)–O(4)#1 88.95(7)

2 Cr(1)–O(4) 1.939(4) O(4)–Cr(1)–O(2) 89.31(17) Cr(1)–O(5) 1.940(4) O(5)–Cr(1)–O(2) 90.61(16) Cr(1)–O(1) 1.949(4) O(1)–Cr(1)–O(2) 89.76(16) Cr(1)–O(2) 1.953(4) O(3)–Cr(1)–O(6) 90.96(16) Cr(1)–O(3) 1.953(4) O(5)–Cr(1)–O(6) 90.65(17) Cr(1)–O(6) 1.979(4) O(1)–Cr(1)–O(6) 91.42(16) C(25)–O(3) 1.290(6) O(4)–Cr(1)–O(5) 87.23(17) C(7)–O(1) 1.318(6) O(4)–Cr(1)–O(1) 90.71(16) C(11)–O(2) 1.299(6) O(2)–Cr(1)–O(6) 89.16(16) C(37)–O(5) 1.290(7) O(4)–Cr(1)–O(3) 90.50(16)

O(1)–Cr(1)–O(3) 92.29(16) O(5)–Cr(1)–O(3) 87.34(16)

In addition, as show in table 4, there are three edge-to-face C–H···π interactions: one C–H···π intramolecular interaction between the CH of the phenyl ring and the pyrazolone ring; two C–H···π intermolecular interactions, one between the CH of the furan ring and the pyrazolone ring of the adjacent [Cr(L)3] units and

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another between the CH of the furan ring and the phenyl ring of the adjacent [Cr(L)3] units. Among them, the two intermolecular C–H···π interactions link the 2D sheets to form a 3D supramolecular structure. It is thus noted that three types of interactions are present in the structures and the incorporation of π···π, C–H···π and H-bonding interactions contacts results in the formation of a stable 3D network structure. The packing diagram and the various molecular interactions such as C–H···π and π···π interactions are calculated using the program PLATON-97 [20].

Table 3 Hydrogen bonds for 1 and 2 [Å and o]. (Symmetry transformations used to generate equivalent atoms: (1) #2 –x+1/2, y-1/2, z).

D–H···A D–H H···A D···A D–H···A 1

O(4)–H(4A)···N(2)#2 0.846(10) 1.922(11) 2.758(2) 169(3) C(6)–H(6)···O(4) 0.93 2.59 3.446(3) 154

C(16)–H(16C)···O(2) 0.96 2.56 3.185(5) 123 2

C(35)–H(35)···N(4) 0.93 2.46 3.3715 168

Table 4 C–H···π interactions for 1 and 2 [Å and o]. (Cg2 is the centroid of ring C7–C9/N2/N1; Cg9 of ring C37–C39/N6/N5, Cg12 of ring C16–C21).

C–H···Cg H···Cg C···Cg C–H···Cg Symmety code 1

C(6)–H(6)···Cg(2) 2.85 3.363(2) 116 1/2–X,1/2+Y,Z 2

C(17)–H(17)···Cg(9) 2.72 3.6037 160 X,Y,Z C(43)–H(43)···Cg(9) 2.88 3.6561 142 1–X,–Y,1–Z C(45)–H(45)···Cg(12) 2.86 3.5521 132 –X,–Y,1–Z

Table 5 π-π interactions for 2 [Å and o]. (The dihedral angle is between the CgI and CgJ planes and the interplanar distance is the perpendicular distance of CgI from ring J and the offset angle is between CgI–centroid vector and normal to plane I).

Cg(I)–Cg(J) Cg···Cg Dihedral angle Interplanar distance Offset angle Symmety code Cg(4)–Cg(7) 3.4782 1.58 3.407 12.04 –X,1–Y,1–Z Cg(5)–Cg(8) 3.5099 12.04 3.346 1.58 –X,1–Y,–Z Cg(7)–Cg(4) 3.4782 1.58 3.410 12.04 –X,1–Y,1–Z Cg(8)–Cg(5) 3.5099 12.04 3.365 1.58 –X,1–Y,–Z

IR spectrum analyses of 1 and 2 In IR spectrum, compared with that of the HL ligand. In the free ligand, a medium-intensity band at 3011 cm-1 is assigned to ν(OH) of β-diketones, the band is absent in complex 1 and 2. A band at 1582 cm-1 in the free ligand is allocated as ν(C=O) of pyrazolone-ring tranfers to the 1560.5 cm-1 in the complex 1 and 2. Weak bands of 489.9 cm-1 and 493.9 cm-1 are related to Co-O and Cr-O stretching vibration respectively. From these observations, it is concluded that the enolic proton of ligand is replaced by Co(II) and Cr(Ш) atom in the complex 1 and 2 respectively.

4 Conclusions

In summary, two new 4-heterocyclic acylpyrazolone complexes 1 and 2 were synthesized by solvothermal method. Their crystal structures have been determined and discussed. Three kinds of aromatic rings of HL play an important role in the formations of complex 1 and 2 by virtue of intra- and/or intermolecular π···π and C–H···π interactions in its complexes. Although central atom (M) of complexes assumes a slight distorted octahedral MO6 coordination geometry, structure of complex 1 is much different from that of complex 2. In complex 1, the methanol molecules at the mixed solvents display better coordination ability. In complex 2, the solvent molecules do not take part in reaction owing to the electron conformation of Cr(Ш). The research on title compounds may provide a reference meaning in crystal growth of β-diketone complexes.

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Acknowledgements This work was supported by (No. 11521061) Scientific Research Foundation of the Education Department of Heilongjiang Province and Special Foundation of Creative Talents in Science and Technology of Harbin City (No2006RFXXG019).

References

[1] S. Yamazaki, M. Hanada, Y. Yanase, C. Fukumori, K. Ogura, T. Saeki, and S. Umetani, J. Chem. Soc. Perkin Trans. 1, 693 (1999).

[2] C. Pettinari, F. Marchetti, and A. Drozdov, in: β-Diketones and Related Ligands, Comprehensive Coordination Chemistry II, Vol. 1 (Elsevier, Camerino, 2003).

[3] G. X. Zheng, Q. F. Wang, and S. G. Luo, J. Radioanal. Nucl. Chem. 258, 693 (2003). [4] J. Z. Li, G. Li, W. and Y. Yu, J. Rare Earth 18, 233 (2000). [5] J. Z. Li, W. Y. Yu, and X. Y. Du, Chin. J. Appl. Chem. 14, 98 (1997). [6] F. Marchetti, C. Pettinari, and R. Pettinari, Coord. Chem. Rev. 249, 2909 (2005). [7] X. M. Zhang, Coordin. Chem. Rev. 249, 1201 (2005). [8] Y. Zhang, J. Z. Li, and H. Q. Zhang, Chin. J. Struct. Chem. 27, 519 (2008). [9] H. Q. Zhang, J. Z. Li, Y. Zhang, D. Zhang, and Z. H Su, Acta. Cryst. E 63, o3536 (2007).

[10] H. Q. Zhang, J. Z. Li, Y. Zhang, and D. Zhang, Chin. J. Inorg. Chem. 24, 990 (2008). [11] B. S. Jensen, Acta. Chem. Scand. 13, 1668 (1959). [12] Bruker SMART, SAINT. Bruker AXS Inc. Madison. Wisconsin, USA 2005. [13] G. M. Sheldrick, SHELXS97 and SHELXL97, Program for the Solution of Crystal Structures, University of

Göttingen, Germany 1997. [14] J. M. Shi, F. X. Zhang, C. J. Wu, and L. D. Liu, Acta Cryst. E 61, m2320 (2005). [15] H. Q. Zhang, J. Z. Li, S. Gao, and Y. Zhang, Acta. Cryst. E 63, m165 (2007). [16] H. Z. Xu, Y. Q. Zhu, X. Zhang, and H. L. Zhu, Acta. Cryst. E 60, m96 (2004). [17] A. B. Uzoukwu, S. S. Al-Juaid, P. B. Hitchcock, and J. D. Smith, Polyhedron 12, 2719 (1993). [18] Y. Akama, M. Kajitani, T. Sugiyama, and A. Sugimori, Anal. Sci. 13, 155 (1997). [19] B. H. Ye, M. L. Tong, and X. M. Chen, Coordin. Chem. Rev. 249, 545 (2005). [20] A. L. Spek, PLATON-97, Molecular Geometry and Plotting Program. University of Utrecht, The Netherlands 1997.