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Synthesis, structure and properties of terephthalate-bridged copper (II) polymeric complex with zigzag chain
Inorganic Chemistry Communications 6 (2003) 573–576 www.elsevier.com/locate/inoche
Synthesis, structure and properties of terephthalate-bridged copper (II) polymeric complex with zigzag chain He-Dong Bian, Jing-Yuan Xu, Wen Gu, Shi-Ping Yan *, Dai-Zheng Liao, Zong-Hui Jiang, Peng Cheng Department of Chemistry, Nankai University, Tianjin 300071, PR China Received 8 October 2002; accepted 9 January 2003
Abstract The complex, f½Cu Lðl2 -taÞðCH3 OHÞ2 gn (L ¼ N,N-dimethyl-N 0 -(pyrid-2-ylmethyl)-ethylene-diamine, ta ¼ terephthalic acid dianion), has been synthesized. X-ray analyses revealed that the copper atom exhibits a distorted square pyramidal geometry, with three nitrogen atoms from the tridentate ligand and two carboxylato-oxygen atoms from different tas. Each ta ligand adopts a l2 ), and the tridentate ligand acts as a terminal ligand with a bridging mode with a typical average Cu–O distance (1.945–2.204 A ). Thus, each ta ligand links two metal centers and each metal center connects two ta ligands to typical Cu–N distance (1.992–2.087 A form the zigzag chain structure. Variable temperature magnetic measurement of the complex shows that a weak ferromagnetic interaction between the copper(II) ions. Ó 2003 Elsevier Science B.V. All rights reserved. Keywords: Terephthalate-bridged; Copper complex; Crystal structure; Zigzag chain
1. Introduction Molecular magnetism has certainly been one of the most active fields in modern inorganic chemistry on account of its promising application to diverse areas of technology such as magnetic recording and magnetic optics [1,2]. In this context, much attention has been paid to the architecture of polymeric magnetic systems, which can provide a better understanding of the correlation between structure and magnetism [3,4]. As a multidentate bridging ligand, terephthalate (ta) has been used in many synthetic systems because they can form short bridges via one carboxylato end or long bridges via the benzene ring, leading a great variety of structures [5,6]. On the other hand, the terephthalato dianion has been proved to be the appropriate bridging unit to design very interesting polymeric magnetic systems with a between the magnetic centers separation of 11–12 A [6–9]. *
Corresponding author. Tel.: +86-022-23509957; fax: +86-2223502779. E-mail address: [email protected] (S.-P. Yan).
In this paper, we report here the synthesis, properties and crystal structure of a new 1D Cu(II)–terephthalato complex with the formula f½Cu Lðl2 -taÞðCH3 OHÞ2 gn , where L stand for the neutral ligand of N,N-dimethylN 0 -(pyrid-2-ylmethyl)-ethylenediamine.
2. Experimental 2.1. General All starting materials were of analytical grade. IR spectra were recorded as KBr discs on a Shimadzu IR408 infrared spectrophotometer in the 4000–600 cm 1 region. The 1 HMR spectra were recorded in CDCl3 with a Bruker 300 MHz spectrometer. Elemental analyses (C, H, N) were performed on a Perkin–Elmer 240C analyser. The ultraviolet and visible spectra were measured on a Shimadzu UV-2101 PC spectrophotometer, water was the solvent in this study. Magnetic susceptibility measurement of a crystalline sample was carried out in the temperature range 4–300 K on a Maglab system2000 magnetometer at a field strength of 10,000 G.
1387-7003/03/$ - see front matter Ó 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S1387-7003(03)00042-X
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H.-D. Bian et al. / Inorganic Chemistry Communications 6 (2003) 573–576
2.2. Synthesis of the ligand L To N,N-dimethylethylenediamine (1.76 g, 20 mmol) in methanol (30 ml) was added pyridine-2-carboxaldehyde (2.14, 20 mmol) in methanol (30 ml) dropwise. The mixture was refluxed for 1 h to get a bright yellow solution and then was evaporated to get a deep red oil. The oil was dissolved in 30 ml methanol and NaBH4 (0.95 g, 25 mmol) was added slowly. The solution was refluxed for 4 h and then was evaporated to dryness. The resulting solid was dissolved in water and extracted with CH2 Cl2 (15 ml 3). The CH2 Cl2 layer was dried over anhydrous magnesium sulfate and was rotaevaporated to get N,N-dimethyl-N 0 -(pyrid-2-ylmethyl)-ethylenediamine as a brownish yellow oil (2.4 g, 67%). [1 HMR (CDCl3 ): 2.37(s; –NðCH3 Þ2 , 6H), 2.66–2.71 (t, –CH2 –, 2H), 2.89–2.93(t, –CH2 –, 2H), 4.05(s, –CH2 –py, 2H), 7.18–7.23(m, pyridyl-CH, 1H), 7.34–7.41(d, pyridyl-CH, 1H), 7.65–7.72(m, pyridyl-CH, 1H), 8.55–8.57(d, pyridyl-CH, 1H).
Table 1 Crystal data and structure refinement for complex 1 Empirical formula Formula weight Temperature Wavelength Crystal system Space group Unit cell dimensions
Volume Z, Calculated density Absorption coefficient h range for data collection Data/restraints/parameters Goodness-of-fit on F 2 Final R indices [I > 2rðIÞ] R indices (all data) Largest diff. peak and hole
C20 H29 CuN3 O6 471.00 293(2) K 0.71073 A Monoclinic P 2ð1Þ=c a ¼ 9:73ð2Þ A b ¼ 18:24ð5Þ A c ¼ 13:43ð4Þ A b ¼ 105:30ð5Þ° 3 2298(10) A 4, 1.361 mg m 3 0.989 mm 1 2.23–23.31° 3173/0/271 0.993 R1 ¼ 0:0664, wR2 ¼ 0:1480 R1 ¼ 0:1598, wR2 ¼ 0:1929 3 0.771 and )0.713 e A
4. Result and discussion 2.3. Synthesis of f½Cu Lðl2 -taÞðCH3 OH Þ2 gn ð1Þ
4.1. Crystal structure of complex 1
To CuðNO3 Þ2 H2 O (0.5 mmol) in 5 ml water was added NaOH (1.0 mmol) solution of 5 ml water with stirring for 0.5 h. The precipitation was filtered, washed with water and then suspended in 10 ml CH3 OH. The solid of ta (0.5 mmol) was added and stirred for 0.5 h. To the mixture, the ligand L (0.5 mmol) in 5 ml CH3 OH was added. The mixture was filtered after 1 h. The blue single crystals suitable for X-ray analysis were separated after several weeks. Element anal.: Calc. (Found) for C20 H29 CuN3 O6 : C, 51.00 (51.07); H, 6.21 (6.13); N, 8.93 (8.22)%.
The copper atom exhibits a distorted square pyramidal geometry (Fig. 1), with the base plane comprised of three nitrogen atoms N(1), N(2), N(3) of the tridentate ligand and a carboxylato-oxygen atom O(3A) and a carboxylato-oxygen atom O(1) of another ta completing the coordination sphere in the apical site. The metal
3. Structure determination A blue crystal (0:45 0:35 0:30 mm) for complex 1 was selected and mounted on a Bruker Smart 1000 diffractometer with graphite monochromatized ), using x scan Mo-Ka radiation (k ¼ 0:71073 A technique at 293(2) K. 7257 reflections were measured in the range of 2:23° 6 h 6 23:31°, and 3173 [RðintÞ ¼ 0:1158] unique reflections with I > 2rðIÞ were used in the succeeding refinements. LP correction was applied to the data. The structure was solved by direct methods in primary method using SHELXL-97 program [10] and refinement on F 2 was performed using SHELXL-97 by full-matrix least-squares with anisotropic thermal parameters for all non-hydrogen atoms. All hydrogen atoms positions were located in calculation positions and isotropically refined. Further details of the structure analysis are given in Table 1.
Fig. 1. View of complex 1 with H omitted for clarity. Selected bond ) and angles (°): Cu(1)–O(3A) 1.948(6), Cu(1)–N(2) 2.004(7), lengths (A Cu(1)–N(1) 2.026(7), Cu(1)–N(3) 2.077(8), Cu(1)–O(1) 2.203(7), O(3)– Cu(1A) 1.948(6), O(3A)–Cu(1)–N(2) 176.7(3), O(3A)–Cu(1)–N(1) 97.8(3), N(2)–Cu(1)–N(1) 81.7(3), O(3A)–Cu(1)–N(3) 94.5(3), N(2)– Cu(1)–N(3) 85.1(3), N(1)–Cu(1)–N(3) 159.0(3), O(3A)–Cu(1)–O(1) 90.4(3), N(2)–Cu(1)–O(1) 92.9(3), N(1)–Cu(1)–O(1) 101.3(3), N(3)– Cu(1)–O(1) 95.6(3). (Symmetry transformations used to generate equivalent atoms: x þ 2, y þ 1=2, z þ 1=2.)
H.-D. Bian et al. / Inorganic Chemistry Communications 6 (2003) 573–576
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Fig. 2. The 2D sheet structure of complex 1 with H and CH3 OH omitted for clarity.
above the base plane. atom is located at 0.1761 A ] distance shows However, the Cu(1)–O(4A) [2.828 A some weak interaction between the copper and the uncoordinated oxygen of ta ligand, which may be viewed as a semi-chelating coordination mode [11]. In each molecule, one of the methanol molecules links with the uncoordinated oxygen atom of ta ligand by hydrogen . bond with the Oð5Þ–Hð5Þ Oð2Þ distance of 2.732 A Each ta ligand adopts a l2 -bridging mode with a ), and the typical average Cu–O distance (1.948–2.203 A tridentate ligand acts as a terminal ligand with a typical ). Thus, each ta ligand Cu–N distance (2.004–2.077 A links two metal centers and each metal center connects two ta ligands to form the zigzag chain structure. Along the bc plane, each chain is connected with two ones by hydrogen bonds, leading to 2D sheets consti 11:284 A rectangles (Fig. 2). The tuted with 17:314 A tridentate ligand C–H groups act as hydrogen donors and the uncoordinated oxygen atoms of tas act as acceptors, with the Cð14Þ–Hð14BÞ Oð4Þ and Cð15Þ– [12], Hð15AÞ Oð4Þ distance of 3.432 and 3.359 A respectively. The dihedral angle in complex 1 between the carboxylate group and the benzene ring is about 5.4°. The carboxylate group shows the expected trigonal geometry with the values of the carbon–oxygen bond distance and [C(1)– O–C–O intracarboxylate bond angle, 1.264 A [C(1)–O(2)], 124.0° [O(1)–C(1)–O(2)], O(1)], 1.247 A [C(8)–O(3)], 1.229 A [C(8)–O(4)], 121.1 [O(3)– 1.323 A C(8)–O(4)]. The intrachain Cu Cu0 distance is 11.284 , whereas the shorter interchain Cu Cu0 one is A . 6.034 A Spectroscopic properties. In the IR spectra, a broad band at about 3350 cm 1 may be attributable to the m(OH) of methanol and the sharp band of 3050 cm 1 can be assigned to the m(NH) stretching frequency of the reduced Schiff base ligand. The absorption band due to
mas (COO) and ms (COO) appear at 1575 and 1345 cm 1 , respectively. Their difference, D ¼ 230 cm 1 , is characteristic of the monodentate coordination mode of the terephthalic dianion [13–16]. The complex shows a broad band centered at about 630 nm (emax ¼ 310 dm3 mol 1 cm 1 ) in water at 298 K which is tentatively attributed to the electronic transitions 2 B1 ! 2 E and 2 B1 ! 2 B2 . This spectrum is typical d–d charge-transfer bands in the square-pyramidal Cu(II) surrounding [17,18]. Magnetic property. The magnetic behaviour of complex 1 is shown in Fig. 3 in the form of leff and vM vs. T. At room temperature the effective magnetic moment equals 1.77lB which is only slightly higher than the spin-only value of monoclear copper(II) S ¼ 1=2 ions (theoretical value for leff ¼ 1:73lB ). A least-squares fit of the data to the equation yields the values of J ¼ 0:02 cm 1 , and g ¼ 2:04, R ¼ 1:5 10 4 . The behavior is characteristic
Fig. 3. A plot for complex 1 of temperature dependence of vM ( ) vs. T and leff (N) vs. T is shown; the solid lines are theoretical fits based on Eq. (1).
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of a weak ferromagnetic interaction between the copper(II) ions. The weak magnetic interaction might be ) [8,19]. due to the long distance of Cu Cu (11.284 A 2=3 Ng2 b2 1 þ Ax þ Bx2 þ Cx3 þ Dx4 þ Ex5 v¼ ; 4jT 1 þ A0 x þ B0 x 2 þ C 0 x 3 þ D 0 x 4 2jJ j : ð1Þ x¼ jT A ¼ 5:7979916, B ¼ 16:902653, C ¼ 29:376885, D ¼ 29:832959, E ¼ 14:036918. A0 ¼ 2:7979916, B0 ¼ 7:0086780, C 0 ¼ 8:6538644, D0 ¼ 4:5743114.
Supplementary material Crystallographic data for the structures of complex 1 in this paper have been deposited at the Cambridge Crystallographic Data Center (CCDC 194309).
Acknowledgements This work was supported by the National Natural Science Foundation of China (No. 20171026) and Tianjin Natural Science Foundation (No. 013605811).
References [1] J.S. Miller, A.J. Epstein, Angew. Chem., Int. Ed. Engl. 33 (1994) 385.
[2] C.P. Landee, M. Melville, J.S. Miller, in: D. Gatteschi, O. Kahn, J.S. Miller, F. Palacio (Eds.), Magnetic Molecular Materials, Kluwer, Dordrecht, The Netherlands, 1991, p. 395. [3] H.O. Stumf, I. Oualmb, Y. Pei, D. Grandjean, O. Kahn, Science 261 (1993) 447. [4] J. Kim, M. Lim, Y.K. Choi, Y. Do, Angew. Chem., Int. Ed. Engl. 35 (1996) 993. [5] H.K. Fun, S.S.S. Raj, R.G. Xiong, J.L. Zuo, Z. Yu, X.Z. You, J. Chem. Soc., Dalton Trans. (1999) 1915. [6] J. Cano, G.D. Munno, J.L. Sanz, R. Ruiz, J. Faus, F. Lloret, M. Julve, A. Caneschi, J. Chem. Soc., Dalton Trans. (1997) 1915. [7] C.S. Hong, Y. Do, Inorg. Chem. 36 (1997) 5684. [8] E.G. Bakalbassis, A.P. Bozopoulos, J. Mrozinski, P.J. Rentzeperis, C.A. Tsipis, Inorg. Chem. 27 (1988) 529. [9] E. Bakalbassis, P. Bergerat, O. Kahn, S. Jeannin, Y. Jeannin, Y. Dromzee, M. Guillot, Inorg. Chem. 31 (1992) 625. [10] A. Bencini, A. Bianchi, P. Paoli, E. Garcia-Espana, M. Julve, V. Marcelino, J. Chem. Soc., Dalton Trans. (1990) 2213. [11] G. Guilera, J.W. Steed, Chem. Commun. (1999) 1563. [12] K.R.J. Ram, K.T. Praveen, F. Xue, C.W.M. Thomas, N. Ashwini, Tetrahedron 56 (2000) 6707. [13] G.B. Deacon, R.J. Phillips, Coord. Chem. Rev. 33 (1980) 227. [14] C.E. Xanthopoulos, M.P. Sigalas, C.C. Hadjikostas, C.A. Tsipis, J. Mrozinski, Int. J. Chem. 2 (1991) 63. [15] E.G. Bakalbassis, J. Mrozinski, C.A. Tsipis, Inorg. Chem. 25 (1986) 3684. [16] E.G. Bakalbassis, C.A. Tsipis, A.P. Bozopoulos, D.W. Dreissig, H. Hartl, J. Mrozinski, Inorg. Chem. 30 (1991) 2801. [17] B.J. Hathaway, Struct. Bonding (Berlin) 57 (1984) 55. [18] B.J. Hathaway, in: G. Wilkinson, R.D. Gillard, J.A. Mccleverty (Eds.), Comprehensive Coordination Chemistry, The Synthesis, Reactions, Properties and Applications of Coordination Compounds, vol. 5, Pergamon, Oxford, 1987, pp. 533– 774. [19] C.E. Xanthopoulox, M.P. Sigalas, G.A. Katsoulos, C.A. Tsipis, A. Terzis, M. Mentzafos, A. Hountas, Inorg. Chem. 32 (1993) 5433.
Synthesis, structure and properties of terephthalate-bridged copper (II) polymeric complex with zigzag chain He-Dong Bian, Jing-Yuan Xu, Wen Gu, Shi-Ping Yan *, Dai-Zheng Liao, Zong-Hui Jiang, Peng Cheng Department of Chemistry, Nankai University, Tianjin 300071, PR China Received 8 October 2002; accepted 9 January 2003
Abstract The complex, f½Cu Lðl2 -taÞðCH3 OHÞ2 gn (L ¼ N,N-dimethyl-N 0 -(pyrid-2-ylmethyl)-ethylene-diamine, ta ¼ terephthalic acid dianion), has been synthesized. X-ray analyses revealed that the copper atom exhibits a distorted square pyramidal geometry, with three nitrogen atoms from the tridentate ligand and two carboxylato-oxygen atoms from different tas. Each ta ligand adopts a l2 ), and the tridentate ligand acts as a terminal ligand with a bridging mode with a typical average Cu–O distance (1.945–2.204 A ). Thus, each ta ligand links two metal centers and each metal center connects two ta ligands to typical Cu–N distance (1.992–2.087 A form the zigzag chain structure. Variable temperature magnetic measurement of the complex shows that a weak ferromagnetic interaction between the copper(II) ions. Ó 2003 Elsevier Science B.V. All rights reserved. Keywords: Terephthalate-bridged; Copper complex; Crystal structure; Zigzag chain
1. Introduction Molecular magnetism has certainly been one of the most active fields in modern inorganic chemistry on account of its promising application to diverse areas of technology such as magnetic recording and magnetic optics [1,2]. In this context, much attention has been paid to the architecture of polymeric magnetic systems, which can provide a better understanding of the correlation between structure and magnetism [3,4]. As a multidentate bridging ligand, terephthalate (ta) has been used in many synthetic systems because they can form short bridges via one carboxylato end or long bridges via the benzene ring, leading a great variety of structures [5,6]. On the other hand, the terephthalato dianion has been proved to be the appropriate bridging unit to design very interesting polymeric magnetic systems with a between the magnetic centers separation of 11–12 A [6–9]. *
Corresponding author. Tel.: +86-022-23509957; fax: +86-2223502779. E-mail address: [email protected] (S.-P. Yan).
In this paper, we report here the synthesis, properties and crystal structure of a new 1D Cu(II)–terephthalato complex with the formula f½Cu Lðl2 -taÞðCH3 OHÞ2 gn , where L stand for the neutral ligand of N,N-dimethylN 0 -(pyrid-2-ylmethyl)-ethylenediamine.
2. Experimental 2.1. General All starting materials were of analytical grade. IR spectra were recorded as KBr discs on a Shimadzu IR408 infrared spectrophotometer in the 4000–600 cm 1 region. The 1 HMR spectra were recorded in CDCl3 with a Bruker 300 MHz spectrometer. Elemental analyses (C, H, N) were performed on a Perkin–Elmer 240C analyser. The ultraviolet and visible spectra were measured on a Shimadzu UV-2101 PC spectrophotometer, water was the solvent in this study. Magnetic susceptibility measurement of a crystalline sample was carried out in the temperature range 4–300 K on a Maglab system2000 magnetometer at a field strength of 10,000 G.
1387-7003/03/$ - see front matter Ó 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S1387-7003(03)00042-X
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H.-D. Bian et al. / Inorganic Chemistry Communications 6 (2003) 573–576
2.2. Synthesis of the ligand L To N,N-dimethylethylenediamine (1.76 g, 20 mmol) in methanol (30 ml) was added pyridine-2-carboxaldehyde (2.14, 20 mmol) in methanol (30 ml) dropwise. The mixture was refluxed for 1 h to get a bright yellow solution and then was evaporated to get a deep red oil. The oil was dissolved in 30 ml methanol and NaBH4 (0.95 g, 25 mmol) was added slowly. The solution was refluxed for 4 h and then was evaporated to dryness. The resulting solid was dissolved in water and extracted with CH2 Cl2 (15 ml 3). The CH2 Cl2 layer was dried over anhydrous magnesium sulfate and was rotaevaporated to get N,N-dimethyl-N 0 -(pyrid-2-ylmethyl)-ethylenediamine as a brownish yellow oil (2.4 g, 67%). [1 HMR (CDCl3 ): 2.37(s; –NðCH3 Þ2 , 6H), 2.66–2.71 (t, –CH2 –, 2H), 2.89–2.93(t, –CH2 –, 2H), 4.05(s, –CH2 –py, 2H), 7.18–7.23(m, pyridyl-CH, 1H), 7.34–7.41(d, pyridyl-CH, 1H), 7.65–7.72(m, pyridyl-CH, 1H), 8.55–8.57(d, pyridyl-CH, 1H).
Table 1 Crystal data and structure refinement for complex 1 Empirical formula Formula weight Temperature Wavelength Crystal system Space group Unit cell dimensions
Volume Z, Calculated density Absorption coefficient h range for data collection Data/restraints/parameters Goodness-of-fit on F 2 Final R indices [I > 2rðIÞ] R indices (all data) Largest diff. peak and hole
C20 H29 CuN3 O6 471.00 293(2) K 0.71073 A Monoclinic P 2ð1Þ=c a ¼ 9:73ð2Þ A b ¼ 18:24ð5Þ A c ¼ 13:43ð4Þ A b ¼ 105:30ð5Þ° 3 2298(10) A 4, 1.361 mg m 3 0.989 mm 1 2.23–23.31° 3173/0/271 0.993 R1 ¼ 0:0664, wR2 ¼ 0:1480 R1 ¼ 0:1598, wR2 ¼ 0:1929 3 0.771 and )0.713 e A
4. Result and discussion 2.3. Synthesis of f½Cu Lðl2 -taÞðCH3 OH Þ2 gn ð1Þ
4.1. Crystal structure of complex 1
To CuðNO3 Þ2 H2 O (0.5 mmol) in 5 ml water was added NaOH (1.0 mmol) solution of 5 ml water with stirring for 0.5 h. The precipitation was filtered, washed with water and then suspended in 10 ml CH3 OH. The solid of ta (0.5 mmol) was added and stirred for 0.5 h. To the mixture, the ligand L (0.5 mmol) in 5 ml CH3 OH was added. The mixture was filtered after 1 h. The blue single crystals suitable for X-ray analysis were separated after several weeks. Element anal.: Calc. (Found) for C20 H29 CuN3 O6 : C, 51.00 (51.07); H, 6.21 (6.13); N, 8.93 (8.22)%.
The copper atom exhibits a distorted square pyramidal geometry (Fig. 1), with the base plane comprised of three nitrogen atoms N(1), N(2), N(3) of the tridentate ligand and a carboxylato-oxygen atom O(3A) and a carboxylato-oxygen atom O(1) of another ta completing the coordination sphere in the apical site. The metal
3. Structure determination A blue crystal (0:45 0:35 0:30 mm) for complex 1 was selected and mounted on a Bruker Smart 1000 diffractometer with graphite monochromatized ), using x scan Mo-Ka radiation (k ¼ 0:71073 A technique at 293(2) K. 7257 reflections were measured in the range of 2:23° 6 h 6 23:31°, and 3173 [RðintÞ ¼ 0:1158] unique reflections with I > 2rðIÞ were used in the succeeding refinements. LP correction was applied to the data. The structure was solved by direct methods in primary method using SHELXL-97 program [10] and refinement on F 2 was performed using SHELXL-97 by full-matrix least-squares with anisotropic thermal parameters for all non-hydrogen atoms. All hydrogen atoms positions were located in calculation positions and isotropically refined. Further details of the structure analysis are given in Table 1.
Fig. 1. View of complex 1 with H omitted for clarity. Selected bond ) and angles (°): Cu(1)–O(3A) 1.948(6), Cu(1)–N(2) 2.004(7), lengths (A Cu(1)–N(1) 2.026(7), Cu(1)–N(3) 2.077(8), Cu(1)–O(1) 2.203(7), O(3)– Cu(1A) 1.948(6), O(3A)–Cu(1)–N(2) 176.7(3), O(3A)–Cu(1)–N(1) 97.8(3), N(2)–Cu(1)–N(1) 81.7(3), O(3A)–Cu(1)–N(3) 94.5(3), N(2)– Cu(1)–N(3) 85.1(3), N(1)–Cu(1)–N(3) 159.0(3), O(3A)–Cu(1)–O(1) 90.4(3), N(2)–Cu(1)–O(1) 92.9(3), N(1)–Cu(1)–O(1) 101.3(3), N(3)– Cu(1)–O(1) 95.6(3). (Symmetry transformations used to generate equivalent atoms: x þ 2, y þ 1=2, z þ 1=2.)
H.-D. Bian et al. / Inorganic Chemistry Communications 6 (2003) 573–576
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Fig. 2. The 2D sheet structure of complex 1 with H and CH3 OH omitted for clarity.
above the base plane. atom is located at 0.1761 A ] distance shows However, the Cu(1)–O(4A) [2.828 A some weak interaction between the copper and the uncoordinated oxygen of ta ligand, which may be viewed as a semi-chelating coordination mode [11]. In each molecule, one of the methanol molecules links with the uncoordinated oxygen atom of ta ligand by hydrogen . bond with the Oð5Þ–Hð5Þ Oð2Þ distance of 2.732 A Each ta ligand adopts a l2 -bridging mode with a ), and the typical average Cu–O distance (1.948–2.203 A tridentate ligand acts as a terminal ligand with a typical ). Thus, each ta ligand Cu–N distance (2.004–2.077 A links two metal centers and each metal center connects two ta ligands to form the zigzag chain structure. Along the bc plane, each chain is connected with two ones by hydrogen bonds, leading to 2D sheets consti 11:284 A rectangles (Fig. 2). The tuted with 17:314 A tridentate ligand C–H groups act as hydrogen donors and the uncoordinated oxygen atoms of tas act as acceptors, with the Cð14Þ–Hð14BÞ Oð4Þ and Cð15Þ– [12], Hð15AÞ Oð4Þ distance of 3.432 and 3.359 A respectively. The dihedral angle in complex 1 between the carboxylate group and the benzene ring is about 5.4°. The carboxylate group shows the expected trigonal geometry with the values of the carbon–oxygen bond distance and [C(1)– O–C–O intracarboxylate bond angle, 1.264 A [C(1)–O(2)], 124.0° [O(1)–C(1)–O(2)], O(1)], 1.247 A [C(8)–O(3)], 1.229 A [C(8)–O(4)], 121.1 [O(3)– 1.323 A C(8)–O(4)]. The intrachain Cu Cu0 distance is 11.284 , whereas the shorter interchain Cu Cu0 one is A . 6.034 A Spectroscopic properties. In the IR spectra, a broad band at about 3350 cm 1 may be attributable to the m(OH) of methanol and the sharp band of 3050 cm 1 can be assigned to the m(NH) stretching frequency of the reduced Schiff base ligand. The absorption band due to
mas (COO) and ms (COO) appear at 1575 and 1345 cm 1 , respectively. Their difference, D ¼ 230 cm 1 , is characteristic of the monodentate coordination mode of the terephthalic dianion [13–16]. The complex shows a broad band centered at about 630 nm (emax ¼ 310 dm3 mol 1 cm 1 ) in water at 298 K which is tentatively attributed to the electronic transitions 2 B1 ! 2 E and 2 B1 ! 2 B2 . This spectrum is typical d–d charge-transfer bands in the square-pyramidal Cu(II) surrounding [17,18]. Magnetic property. The magnetic behaviour of complex 1 is shown in Fig. 3 in the form of leff and vM vs. T. At room temperature the effective magnetic moment equals 1.77lB which is only slightly higher than the spin-only value of monoclear copper(II) S ¼ 1=2 ions (theoretical value for leff ¼ 1:73lB ). A least-squares fit of the data to the equation yields the values of J ¼ 0:02 cm 1 , and g ¼ 2:04, R ¼ 1:5 10 4 . The behavior is characteristic
Fig. 3. A plot for complex 1 of temperature dependence of vM ( ) vs. T and leff (N) vs. T is shown; the solid lines are theoretical fits based on Eq. (1).
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of a weak ferromagnetic interaction between the copper(II) ions. The weak magnetic interaction might be ) [8,19]. due to the long distance of Cu Cu (11.284 A 2=3 Ng2 b2 1 þ Ax þ Bx2 þ Cx3 þ Dx4 þ Ex5 v¼ ; 4jT 1 þ A0 x þ B0 x 2 þ C 0 x 3 þ D 0 x 4 2jJ j : ð1Þ x¼ jT A ¼ 5:7979916, B ¼ 16:902653, C ¼ 29:376885, D ¼ 29:832959, E ¼ 14:036918. A0 ¼ 2:7979916, B0 ¼ 7:0086780, C 0 ¼ 8:6538644, D0 ¼ 4:5743114.
Supplementary material Crystallographic data for the structures of complex 1 in this paper have been deposited at the Cambridge Crystallographic Data Center (CCDC 194309).
Acknowledgements This work was supported by the National Natural Science Foundation of China (No. 20171026) and Tianjin Natural Science Foundation (No. 013605811).
References [1] J.S. Miller, A.J. Epstein, Angew. Chem., Int. Ed. Engl. 33 (1994) 385.
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