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Synthesis, structure and magnetic property of a one-dimensional Co(II)-formate helical coordination polymer
Journal of Molecular Structure 890 (2008) 112–115
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Journal of Molecular Structure journal homepage: www.elsevier.com/locate/molstruc
Synthesis, structure and magnetic property of a one-dimensional Co(II)-formate helical coordination polymer Pei-Lin Yuan a,b, Pei-Zhou Li c, Qing-Fu Sun b, Li-Xia Liu b, Kun Gao a, Wei-Sheng Liu a, Xiao-Ming Lu c, Shu-Yan Yu a,b,* a
College of Chemistry and Chemical Engineering and National Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, PR China Laboratory for Self-Assembly Chemistry, Department of Chemistry, Renmin University of China, Beijing 100872, PR China c Department of Chemistry, Capital Normal University, Beijing 100037, PR China b
a r t i c l e
i n f o
Article history: Received 4 January 2008 Received in revised form 9 May 2008 Accepted 9 May 2008 Available online 20 May 2008 Keywords: Cobalt(II)-formate coordination polymer Helical chain Hydrogen bonds Ferrimagnetic property
a b s t r a c t An one-dimensional coordination polymer, {[Co(II)(OOCH)2(phen)(H2O)]H2O}n (1) (phen = 1,10-phenanthroline), has been synthesized by solvo-thermal reaction. Single-crystal X-ray diffraction analysis shows that 1 is an one-dimensional formate-bridged (phen)Co(II) helical chain, which is crystallized in non-centrosymmetric Pna2(1) space group of orthorhombic crystal system. The temperature (2–300 K) dependent magnetic susceptibility of 1 corresponds to a typical shape of ferrimagnetic system. Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
Design and construction of multi-dimensional functional coordination polymers with metal ions as nodes and bridged ligands as spacers has attracted chemist’s much attention in recent years [1–3]. This is arisen not only for their various intriguing topological structures, but also for their unexpected properties for potential practical applications in material chemistry, such as heterogeneous catalysis, gas sorption, storage and separations, molecular recognition, nonlinear optics, luminescent and magnetic properties [4–6]. Selection of appropriate ligand to link metal ions or metal clusters is a powerful way for the construction of coordination polymers. The versatility of carboxylate ligands for ligating and connecting metal centers has led to extensive research on the structures and properties of polymeric carboxylate complexes. Herein, by using formate anion to link two aromatic diimine ligand (phen) coordinated Co(II) centers, we have successfully synthesized a ferrimagnetic onedimensional helical coordination polymer, {[Co(II)(OOCH)2(phen) (H2O)]H2O}n (1) (phen = 1,10-phenanthroline).
2.1. Materials and general methods
* Corresponding author. Address: College of Chemistry and Chemical Engineering and National Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, PR China. Tel./fax: +86 10 62516614. E-mail address: [email protected] (S.-Y. Yu). 0022-2860/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.molstruc.2008.05.022
All reagents for synthesis and analysis were obtained commercially with analytical grade and used without further purification and all manipulation was carried out in the laboratory atmosphere. Elemental C, H and N analyses were performed on a Perkin Elmer analyzer. Infrared spectra were recorded as KBr pellets on a Bruker EQUIN0X 55 IR spectrometer. The magnetic property study has been performed on a crystalline sample using a MPMS-XL-SQUID magnetometer. 2.2. Syntheses A mixture of CoCl26H2O (0.238 g, 1 mmol) in water (10 mL), and 1,10-phenanthroline (0.198 g, 1 mmol) and formic acid (0.140 g, 3 mmol) in DMF (10 mL) were added into a Teflon-Steel autoclave inside programmable electric furnace reactor. Mixed-solvo-thermal reaction lasted for about 48 h at about 423.15 K, and then cooled to room temperature naturally. Then brown crystals of compound 1 were obtained (yield: about 63.5%). Anal. Calc. for 1 (%): C, 46.00; H, 3.86; N, 7.67; Found (%): C, 46.12; H, 3.96; N, 7.78. IR (KBr): 3355.26s, 1620.45s, 1580.43w, 1534.44m, 1513.02m, 1481.64w, 1445.10m, 1396.42s, 1330.43s, 1270.76w, 1218.91w, 1165.12w, 1137.77w, 1089.98w, 848.56w, 724.95m, 523m.
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2.3. Crystallographic data collection and structure determination
3. Results and discussion
Single-crystal X-ray diffraction study of complex 1 was performed on a Bruker SMART diffractometer equipped with CCD area detector with a graphite monochromator situated in the incident beam for data collection. The determination of unit cell parameters and data collections were performed with Mo Ka radiation (k = 0.71073 Å) by x scan mode in the range of 2.02 h 28.72 at 293(2) K. The data were corrected by semi-empirical method using SADABS program. The program SAINT [7] was used for integration of the diffraction profiles. The structure was solved by direct methods using SHELXS program of the SHELXTL-97 package and refined with SHELXL [8]. Metal atom centers were located from the E-maps and other non-hydrogen atoms were located in successive difference Fourier syntheses. The final refinements were performed by full matrix least-squares methods with anisotropic thermal parameters for non-hydrogen atoms on F2. All the hydrogen atoms were first found in difference electron density maps, and then placed in the calculated sites and included in the final refinement in the riding model approximation with displacement parameters derived from the parent atoms to which they were bonded. Further crystallographic data and experimental details for structural analysis of 1 are summarized in Table 1, and selected bond lengths and angles with their estimated standard deviations are in Table 2.
3.1. Structure analysis
Table 1 Crystallographic data and structure refinement summary for complexes 1 Formula Mr Temperature Wavelength (Å) Crystal system Space group a (Å) b (Å) c (Å) V (Å3) Z Dcalc (g cm 3) Goodness-of-fit on F2 Crystal size (mm) Theta range (°) Reflections collected/unique Rint Refinement method Final R1 and wR2 indices R1 and wR2 indices (all data) Min, max peaks (e Å 3)
C14H14CoN2O6 365.20 290(2) 0.71073 Orthorhombic Pna2(1) (non-centrosymmetric) 19.0714(6) 12.0458(4) 6.4145(2) 1473.60(8) 4 1.646 1.003 0.24 0.22 0.20 2.00–28.27 8425/3109 0.0332 Full-matrix least-squares on F2 R1 = 0.0355, wR2 = 0.0613 R1 = 0.0528, wR2 = 0.0675 0.262 and 0.306
The structure analysis shows that 1 is an neutral one-dimensional Co(II)-formate coordination helical coordination polymer. As shown in Fig. 1a, each Co(II) atom is coordinated by (i) two N donors of 1,10-phenanthroline with the Co–N distance of 2.115(3)–2.153(2) Å, (ii) two oxygen atoms of two bridging formate anion with the Co–O distance of 2.0876(19)–2.1381(19) Å, (iii) one oxygen atom of one terminal formate anion with the Co–O distance of 2.064(2) Å and (iv) one coordinated water with the Co–O distance of 2.085(2) Å forming a octahedral coordination sphere. Then two neighboring Co(II) centers connected by formate anion with the distance of 5.387(2) Å from a 1D infinite chain (Fig. 1b). But the 1,10-phenanthroline molecules acting as terminal ligand prevent the chain from spreading along the straightforward direction, then the inner-chain hydrogen bonds formed between the O–H group of coordinated water molecules and the oxygen atoms of the carboxyl groups from the bridged formate anion make it into a left- or right-handed helical chain (Fig. 1c). Interestingly, analysis of the crystal packing of 1 indicates that two neighboring helical chains are connected by three kinds of independent inter-chain O–H O hydrogen bonds formed by the uncoordinated water molecules (Fig. 1d, Table 3). One kind of the inter-chain O–H O hydrogen bonds is formed between the O–H group of coordinated water molecules acting as donors and the oxygen atoms of the uncoordinated water molecules acting as acceptors (the D A distance is 2.660(4) Å with a O–H O angle of 170(4)°). The other two kinds are formed between the O–H groups of uncoordinated water molecules and the uncoordinated oxygen atoms of the carboxyl groups from the coordinated terminal formate anions in two adjacent chains, with two different D A distances of 2.736(5) and 2.784(5) Å, and two different O–H O angles of 173(6)° and 157(7)°, respectively. 3.2. Magnetic property The magnetic property study has been performed on a crystal sample using a MPMS-XL-SQUID magnetometer in a temperature range of 2–300 K. The variable-temperature magnetic behavior at fixed field strength of 1000 Oe for 1 is shown in Fig. 2. The value of vMT at 300 K is 2.532 cm3 mol-1 K and thus is higher than the spin-only value of 1.875 cm3 mol 1 K that expected for an uncoupled high-spin Co(II) ion (S = 3/2, g = 2), in accordance with the well-documented orbital contribution of the octahedral Co(II) ion [9]. The magnetic susceptibility above 30 K obeys the Curie–Weiss law with a Weiss constant, h = 2.93(3) K, and a Curie constant,
Table 2 Selected bond lengths (Å) and angles (°) for complex 1 Co(1)–O(1) Co(1)–O(5) Co(1)–O(3) Co(1)–O(4) O(1)–Co(1)–O(4) O(3)–Co(1)–O(4) O(1)–Co(1)–O(5) O(1)–Co(1)–O(3) O(5)–Co(1)–O(3) O(5)–Co(1)–O(4)
2.064(2) 2.085(2) 2.0876(19) 2.1381(19) 171.57(10) 83.67(8) 93.51(10) 89.51(8) 91.09(9) 91.58(9)
Co(1)–N(1) Co(1)–N(2) O(1)–C(13)
2.153(2) 2.115(3) 1.226(4)
O(3)–Co(1)–N(1) O(5)–Co(1)–N(2) O(3)–Co(1)–N(2) O(1)–Co(1)–N(1) O(5)–Co(1)–N(1)
Symmetry transformations used to generate equivalent atoms: #1
x + 1,
y + 1, z
172.36(10) 173.68(11) 94.11(10) 91.61(9) 96.39(11)
1/2; #2
x + 1,
y + 1, z + 1/2.
C(13)–O(2) O(3)–C(14) O(4)–C(14)#1 N(2)–Co(1)–N(1) O(1)–Co(1)–N(2) N(2)–Co(1)–O(4) O(1)–C(13)–O(2) O(4)#2–C(14)–O(3)
1.242(4) 1.249(3) 1.241(3) 78.33(10) 90.13(10) 85.43(8) 125.3(4) 126.7(3)
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P.-L. Yuan et al. / Journal of Molecular Structure 890 (2008) 112–115
Fig. 1. (a) Perspective view of the basic unit of the one-dimensional helical chain of 1; (b) Perspective view of the one-dimensional helical chain of 1, showing the inter-chain hydrogen bonds and the p–p packing interactions. (c) Perspective view of the left-handed and right-handed one-dimensional helical chains in 1. (d) Perspective view of two neighboring homo-helical chains interactions showing the inter-chain hydrogen bonds in 1.
C = 2.65(1) cm3 mol 1 K, indicating the presence of a dominant paramagnetic interaction (Fig. 2). As the sample is cooled from room temperature, the vMT value falls to 1.63 cm3 mol 1 K at 10 K and then rises at lower temperatures to reach a maximum value of 2.21 cm3mol 1 K at 2 K. This corresponds to a typical shape of ferrimagnetic system.
The ferrimagnetic property of 1 can be suggested to arise from intrachain magnetic interactions. There are two kinds of magnetic exchange pathways in compound 1 with a J1J2 repeating sequence according to the chain topology: one is formate bridge; the other is O–H O bridge through the intrachain hydrogen bonds (Fig. 1b). Due to non-compensation in spin mo-
P.-L. Yuan et al. / Journal of Molecular Structure 890 (2008) 112–115 Table 3 H-bonds parameters of the compound 1 (Å and °)
4. Conclusion and comments
Donor–H Acceptor
D–H
H A
D A
\(DHA)
O(5)–H(5A) O(3)#1 O(6)–H(6A) O(2)#1 O(6)–H(6B) O(2)#3 O(5)–H(5B) O(6)#1
0.82 0.69(7) 0.77(5) 0.74(4)
1.92 2.14(8) 1.97(5) 1.93(4)
2.665(3) 2.784(5) 2.736(5) 2.660(4)
149.8 157(7) 173(6) 170(4)
Symmetry transformations used to generate equivalent atoms: #1 z 1/2. #2 x + 1, y + 1, z + ½, #3 x, y + 1, z.
1.2
/ cm-3 mol
-1
0.6
M
-1
0.8
Supplementary data
2.4 2.2
80
2.0
60
1.8
40
1.6 20
T /cm 3· k · mol -1
M
-1 M T M
1.4
0.4
0 1.2 0
50
100
0.2
150
200
250
In summary, a 1D Co(II)-formate coordination helical coordination polymer has been synthesized by solvo-thermal reaction, and characterized by single-crystal X-ray diffraction study. The study of the temperature dependent magnetic susceptibility for the complex revealed a ferrimagnetic property.
y + 1,
M
/ mol cm
1.0
x + 1,
2.6
120 100
115
300
T/K
Crystallographic data for the crystal structure reported in this paper has been deposited with the Cambridge Crystallographic Data Center (CCDC No. 668762). This data can be obtained free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html or from the CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: +44 1223 336 033; or e-mail: [email protected]). Acknowledgements This project was supported by National Natural Science Foundation of China. (Nos. 50673098 and 20772152) and National Laboratory of Applied Organic Chemistry (Lanzhou University). It is our great honor that Dr. F. Albert Cotton was awarded honorary doctorate of Lanzhou University in 2006.
0.0 0
50
100
150
200
250
300
T/K Fig. 2. The thermal variation of vM, vM
1
and vMT of 1.
Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.molstruc.2008.05.022. References
S=3
S=3/2 Chart 1. Spin topology of the (3, 3/2) ferrimagnetic chain.
ments within such a chain, the magnetic exchange through the former kind of exchange pathway should be antiferromagnetic (AF) and that through the latter must be ferromagnetic (F). The exchanges alternate according to an AF–F repeating sequence to produce the spin topology that corresponds to a (3, 3/2) ferrimagnetic chain (Chart 1). To evaluate the exchanges, a nonlinear least-squares fitting of the theoretical expression proposed by Escuer et al. [10] to the experimental data has been performed by varying g, J1, J2 and minP P imizing the residual R = [ (vobsT vcalcT)2/ (vobsT)2] (Fig. 2). The best fit to the data above 2 K is achieved with g = 1.73, J1 = 1.45 cm 1, J2 = 0.62 cm 1, R = 0.60 10 4. The J1 value is associated with the antiferromagnetic exchange through the formate bridge, whereas O–H O bridge mediate a ferromagnetic (J2) interaction, J1 < 0 (JAF) and J2 > 0 (JF), and relative values |JAF| >> JF.
[1] F.A. Cotton, G. Wilkinson, C.A. Murillo, M. Bochmann, Advanced Inorganic Chemistry, John Willey & Sons, New York, 1999. [2] F.A. Cotton, C.A. Murillo, R.A. Walton, Multiple Bonds between Metal Atoms, Springer Science and Business Media, Inc., 2005. [3] (a) S. Kitagawa, R. Kitaura, S.-I. Noro, Angew. Chem. Int. Ed. 43 (2004) 2334– 2375; (b) J.L.C. Rowsell, E.C. Spencer, J. Eckert, J.A.K. Howard, O.M. Yaghi, Science 309 (2005) 1350–1354; (c) S.R. Battern, R. Robson, Angew. Chem. Int. Ed. 37 (1998) 1460–1494. [4] (a) M. Fujita, Y.J.J. Kwon, Am. Chem. Soc. 116 (1994) 1151–1152; (b) J.S. Seo, D. Whang, H. Lee, Nature 404 (2000) 982–986; (c) Y.-Z. Zheng, M.-L. Tong, W.-X. Zhang, X.-M. Chen, Angew. Chem. Int. Ed. 45 (2006) 6310–6314; (d) Y. Liu, G. Li, X. Li, Y. Cui, Angew. Chem. Int. Ed. 46 (2007) 6301–6304. [5] (a) S.-Y. Yu, M. Fujita, K. Yamaguchi, J. Chem. Soc. Dalton Trans. (2001) 3419– 3420; (b) H.-B. Liu, S.-Y. Yu, H. Huang, Z.-X. Zhang, Aust. J. Chem. 56 (2003) 671–674; (c) H. Huang, S.-Y. Yu, H.-B. Liu, M. Shi, Polyhedron 23 (2004) 55–58. [6] (a) P.-Z. Li, X.-M. Lu, B. Liu, S. Wang, X.-J. Wang, Inorg. Chem. 46 (2007) 5823– 5825; (b) X.-M. Lu, B. Liu, S. Wang, Y. Deng, Inorg. Chem. Commun. 9 (2006) 403–406. [7] Bruker AXS, SAINT Software Reference Manual, Madison, WI, 1998. [8] G.M. Sheldrick, SHELXTL NT Version 5.1. Program for Solution and Refinement }ttingen, Germany, 1997. of Crystal Structures, University of Go [9] (a) F.E. Mabbs, D.J. Machin, Magnetism and Transition Metal Complexes, Chapman and Hall, London, 1973; (b) B.N. Figgis, M.A. Hitchman, Ligand Field Theory and Its Applications, WileyVCH, New York, 2000. [10] (a) M.A.M. Abu-Youssef, M. Drillon, A. Escuer, M.A.S. Goher, F.A. Mautner, R. Vicente, Inorg. Chem. 39 (2000) 5022–5027; (b) A. Escuer, F.A. Mautner, M.A.S. Goher, M.A.M. Abu-Youssef, R. Vicente, Chem. Commun. (2005) 605–606.
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Journal of Molecular Structure journal homepage: www.elsevier.com/locate/molstruc
Synthesis, structure and magnetic property of a one-dimensional Co(II)-formate helical coordination polymer Pei-Lin Yuan a,b, Pei-Zhou Li c, Qing-Fu Sun b, Li-Xia Liu b, Kun Gao a, Wei-Sheng Liu a, Xiao-Ming Lu c, Shu-Yan Yu a,b,* a
College of Chemistry and Chemical Engineering and National Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, PR China Laboratory for Self-Assembly Chemistry, Department of Chemistry, Renmin University of China, Beijing 100872, PR China c Department of Chemistry, Capital Normal University, Beijing 100037, PR China b
a r t i c l e
i n f o
Article history: Received 4 January 2008 Received in revised form 9 May 2008 Accepted 9 May 2008 Available online 20 May 2008 Keywords: Cobalt(II)-formate coordination polymer Helical chain Hydrogen bonds Ferrimagnetic property
a b s t r a c t An one-dimensional coordination polymer, {[Co(II)(OOCH)2(phen)(H2O)]H2O}n (1) (phen = 1,10-phenanthroline), has been synthesized by solvo-thermal reaction. Single-crystal X-ray diffraction analysis shows that 1 is an one-dimensional formate-bridged (phen)Co(II) helical chain, which is crystallized in non-centrosymmetric Pna2(1) space group of orthorhombic crystal system. The temperature (2–300 K) dependent magnetic susceptibility of 1 corresponds to a typical shape of ferrimagnetic system. Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
Design and construction of multi-dimensional functional coordination polymers with metal ions as nodes and bridged ligands as spacers has attracted chemist’s much attention in recent years [1–3]. This is arisen not only for their various intriguing topological structures, but also for their unexpected properties for potential practical applications in material chemistry, such as heterogeneous catalysis, gas sorption, storage and separations, molecular recognition, nonlinear optics, luminescent and magnetic properties [4–6]. Selection of appropriate ligand to link metal ions or metal clusters is a powerful way for the construction of coordination polymers. The versatility of carboxylate ligands for ligating and connecting metal centers has led to extensive research on the structures and properties of polymeric carboxylate complexes. Herein, by using formate anion to link two aromatic diimine ligand (phen) coordinated Co(II) centers, we have successfully synthesized a ferrimagnetic onedimensional helical coordination polymer, {[Co(II)(OOCH)2(phen) (H2O)]H2O}n (1) (phen = 1,10-phenanthroline).
2.1. Materials and general methods
* Corresponding author. Address: College of Chemistry and Chemical Engineering and National Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, PR China. Tel./fax: +86 10 62516614. E-mail address: [email protected] (S.-Y. Yu). 0022-2860/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.molstruc.2008.05.022
All reagents for synthesis and analysis were obtained commercially with analytical grade and used without further purification and all manipulation was carried out in the laboratory atmosphere. Elemental C, H and N analyses were performed on a Perkin Elmer analyzer. Infrared spectra were recorded as KBr pellets on a Bruker EQUIN0X 55 IR spectrometer. The magnetic property study has been performed on a crystalline sample using a MPMS-XL-SQUID magnetometer. 2.2. Syntheses A mixture of CoCl26H2O (0.238 g, 1 mmol) in water (10 mL), and 1,10-phenanthroline (0.198 g, 1 mmol) and formic acid (0.140 g, 3 mmol) in DMF (10 mL) were added into a Teflon-Steel autoclave inside programmable electric furnace reactor. Mixed-solvo-thermal reaction lasted for about 48 h at about 423.15 K, and then cooled to room temperature naturally. Then brown crystals of compound 1 were obtained (yield: about 63.5%). Anal. Calc. for 1 (%): C, 46.00; H, 3.86; N, 7.67; Found (%): C, 46.12; H, 3.96; N, 7.78. IR (KBr): 3355.26s, 1620.45s, 1580.43w, 1534.44m, 1513.02m, 1481.64w, 1445.10m, 1396.42s, 1330.43s, 1270.76w, 1218.91w, 1165.12w, 1137.77w, 1089.98w, 848.56w, 724.95m, 523m.
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2.3. Crystallographic data collection and structure determination
3. Results and discussion
Single-crystal X-ray diffraction study of complex 1 was performed on a Bruker SMART diffractometer equipped with CCD area detector with a graphite monochromator situated in the incident beam for data collection. The determination of unit cell parameters and data collections were performed with Mo Ka radiation (k = 0.71073 Å) by x scan mode in the range of 2.02 h 28.72 at 293(2) K. The data were corrected by semi-empirical method using SADABS program. The program SAINT [7] was used for integration of the diffraction profiles. The structure was solved by direct methods using SHELXS program of the SHELXTL-97 package and refined with SHELXL [8]. Metal atom centers were located from the E-maps and other non-hydrogen atoms were located in successive difference Fourier syntheses. The final refinements were performed by full matrix least-squares methods with anisotropic thermal parameters for non-hydrogen atoms on F2. All the hydrogen atoms were first found in difference electron density maps, and then placed in the calculated sites and included in the final refinement in the riding model approximation with displacement parameters derived from the parent atoms to which they were bonded. Further crystallographic data and experimental details for structural analysis of 1 are summarized in Table 1, and selected bond lengths and angles with their estimated standard deviations are in Table 2.
3.1. Structure analysis
Table 1 Crystallographic data and structure refinement summary for complexes 1 Formula Mr Temperature Wavelength (Å) Crystal system Space group a (Å) b (Å) c (Å) V (Å3) Z Dcalc (g cm 3) Goodness-of-fit on F2 Crystal size (mm) Theta range (°) Reflections collected/unique Rint Refinement method Final R1 and wR2 indices R1 and wR2 indices (all data) Min, max peaks (e Å 3)
C14H14CoN2O6 365.20 290(2) 0.71073 Orthorhombic Pna2(1) (non-centrosymmetric) 19.0714(6) 12.0458(4) 6.4145(2) 1473.60(8) 4 1.646 1.003 0.24 0.22 0.20 2.00–28.27 8425/3109 0.0332 Full-matrix least-squares on F2 R1 = 0.0355, wR2 = 0.0613 R1 = 0.0528, wR2 = 0.0675 0.262 and 0.306
The structure analysis shows that 1 is an neutral one-dimensional Co(II)-formate coordination helical coordination polymer. As shown in Fig. 1a, each Co(II) atom is coordinated by (i) two N donors of 1,10-phenanthroline with the Co–N distance of 2.115(3)–2.153(2) Å, (ii) two oxygen atoms of two bridging formate anion with the Co–O distance of 2.0876(19)–2.1381(19) Å, (iii) one oxygen atom of one terminal formate anion with the Co–O distance of 2.064(2) Å and (iv) one coordinated water with the Co–O distance of 2.085(2) Å forming a octahedral coordination sphere. Then two neighboring Co(II) centers connected by formate anion with the distance of 5.387(2) Å from a 1D infinite chain (Fig. 1b). But the 1,10-phenanthroline molecules acting as terminal ligand prevent the chain from spreading along the straightforward direction, then the inner-chain hydrogen bonds formed between the O–H group of coordinated water molecules and the oxygen atoms of the carboxyl groups from the bridged formate anion make it into a left- or right-handed helical chain (Fig. 1c). Interestingly, analysis of the crystal packing of 1 indicates that two neighboring helical chains are connected by three kinds of independent inter-chain O–H O hydrogen bonds formed by the uncoordinated water molecules (Fig. 1d, Table 3). One kind of the inter-chain O–H O hydrogen bonds is formed between the O–H group of coordinated water molecules acting as donors and the oxygen atoms of the uncoordinated water molecules acting as acceptors (the D A distance is 2.660(4) Å with a O–H O angle of 170(4)°). The other two kinds are formed between the O–H groups of uncoordinated water molecules and the uncoordinated oxygen atoms of the carboxyl groups from the coordinated terminal formate anions in two adjacent chains, with two different D A distances of 2.736(5) and 2.784(5) Å, and two different O–H O angles of 173(6)° and 157(7)°, respectively. 3.2. Magnetic property The magnetic property study has been performed on a crystal sample using a MPMS-XL-SQUID magnetometer in a temperature range of 2–300 K. The variable-temperature magnetic behavior at fixed field strength of 1000 Oe for 1 is shown in Fig. 2. The value of vMT at 300 K is 2.532 cm3 mol-1 K and thus is higher than the spin-only value of 1.875 cm3 mol 1 K that expected for an uncoupled high-spin Co(II) ion (S = 3/2, g = 2), in accordance with the well-documented orbital contribution of the octahedral Co(II) ion [9]. The magnetic susceptibility above 30 K obeys the Curie–Weiss law with a Weiss constant, h = 2.93(3) K, and a Curie constant,
Table 2 Selected bond lengths (Å) and angles (°) for complex 1 Co(1)–O(1) Co(1)–O(5) Co(1)–O(3) Co(1)–O(4) O(1)–Co(1)–O(4) O(3)–Co(1)–O(4) O(1)–Co(1)–O(5) O(1)–Co(1)–O(3) O(5)–Co(1)–O(3) O(5)–Co(1)–O(4)
2.064(2) 2.085(2) 2.0876(19) 2.1381(19) 171.57(10) 83.67(8) 93.51(10) 89.51(8) 91.09(9) 91.58(9)
Co(1)–N(1) Co(1)–N(2) O(1)–C(13)
2.153(2) 2.115(3) 1.226(4)
O(3)–Co(1)–N(1) O(5)–Co(1)–N(2) O(3)–Co(1)–N(2) O(1)–Co(1)–N(1) O(5)–Co(1)–N(1)
Symmetry transformations used to generate equivalent atoms: #1
x + 1,
y + 1, z
172.36(10) 173.68(11) 94.11(10) 91.61(9) 96.39(11)
1/2; #2
x + 1,
y + 1, z + 1/2.
C(13)–O(2) O(3)–C(14) O(4)–C(14)#1 N(2)–Co(1)–N(1) O(1)–Co(1)–N(2) N(2)–Co(1)–O(4) O(1)–C(13)–O(2) O(4)#2–C(14)–O(3)
1.242(4) 1.249(3) 1.241(3) 78.33(10) 90.13(10) 85.43(8) 125.3(4) 126.7(3)
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P.-L. Yuan et al. / Journal of Molecular Structure 890 (2008) 112–115
Fig. 1. (a) Perspective view of the basic unit of the one-dimensional helical chain of 1; (b) Perspective view of the one-dimensional helical chain of 1, showing the inter-chain hydrogen bonds and the p–p packing interactions. (c) Perspective view of the left-handed and right-handed one-dimensional helical chains in 1. (d) Perspective view of two neighboring homo-helical chains interactions showing the inter-chain hydrogen bonds in 1.
C = 2.65(1) cm3 mol 1 K, indicating the presence of a dominant paramagnetic interaction (Fig. 2). As the sample is cooled from room temperature, the vMT value falls to 1.63 cm3 mol 1 K at 10 K and then rises at lower temperatures to reach a maximum value of 2.21 cm3mol 1 K at 2 K. This corresponds to a typical shape of ferrimagnetic system.
The ferrimagnetic property of 1 can be suggested to arise from intrachain magnetic interactions. There are two kinds of magnetic exchange pathways in compound 1 with a J1J2 repeating sequence according to the chain topology: one is formate bridge; the other is O–H O bridge through the intrachain hydrogen bonds (Fig. 1b). Due to non-compensation in spin mo-
P.-L. Yuan et al. / Journal of Molecular Structure 890 (2008) 112–115 Table 3 H-bonds parameters of the compound 1 (Å and °)
4. Conclusion and comments
Donor–H Acceptor
D–H
H A
D A
\(DHA)
O(5)–H(5A) O(3)#1 O(6)–H(6A) O(2)#1 O(6)–H(6B) O(2)#3 O(5)–H(5B) O(6)#1
0.82 0.69(7) 0.77(5) 0.74(4)
1.92 2.14(8) 1.97(5) 1.93(4)
2.665(3) 2.784(5) 2.736(5) 2.660(4)
149.8 157(7) 173(6) 170(4)
Symmetry transformations used to generate equivalent atoms: #1 z 1/2. #2 x + 1, y + 1, z + ½, #3 x, y + 1, z.
1.2
/ cm-3 mol
-1
0.6
M
-1
0.8
Supplementary data
2.4 2.2
80
2.0
60
1.8
40
1.6 20
T /cm 3· k · mol -1
M
-1 M T M
1.4
0.4
0 1.2 0
50
100
0.2
150
200
250
In summary, a 1D Co(II)-formate coordination helical coordination polymer has been synthesized by solvo-thermal reaction, and characterized by single-crystal X-ray diffraction study. The study of the temperature dependent magnetic susceptibility for the complex revealed a ferrimagnetic property.
y + 1,
M
/ mol cm
1.0
x + 1,
2.6
120 100
115
300
T/K
Crystallographic data for the crystal structure reported in this paper has been deposited with the Cambridge Crystallographic Data Center (CCDC No. 668762). This data can be obtained free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html or from the CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: +44 1223 336 033; or e-mail: [email protected]). Acknowledgements This project was supported by National Natural Science Foundation of China. (Nos. 50673098 and 20772152) and National Laboratory of Applied Organic Chemistry (Lanzhou University). It is our great honor that Dr. F. Albert Cotton was awarded honorary doctorate of Lanzhou University in 2006.
0.0 0
50
100
150
200
250
300
T/K Fig. 2. The thermal variation of vM, vM
1
and vMT of 1.
Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.molstruc.2008.05.022. References
S=3
S=3/2 Chart 1. Spin topology of the (3, 3/2) ferrimagnetic chain.
ments within such a chain, the magnetic exchange through the former kind of exchange pathway should be antiferromagnetic (AF) and that through the latter must be ferromagnetic (F). The exchanges alternate according to an AF–F repeating sequence to produce the spin topology that corresponds to a (3, 3/2) ferrimagnetic chain (Chart 1). To evaluate the exchanges, a nonlinear least-squares fitting of the theoretical expression proposed by Escuer et al. [10] to the experimental data has been performed by varying g, J1, J2 and minP P imizing the residual R = [ (vobsT vcalcT)2/ (vobsT)2] (Fig. 2). The best fit to the data above 2 K is achieved with g = 1.73, J1 = 1.45 cm 1, J2 = 0.62 cm 1, R = 0.60 10 4. The J1 value is associated with the antiferromagnetic exchange through the formate bridge, whereas O–H O bridge mediate a ferromagnetic (J2) interaction, J1 < 0 (JAF) and J2 > 0 (JF), and relative values |JAF| >> JF.
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