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A two-dimensional copper polymer constructed from rod-shaped ferromagnetic secondary building units
Inorganic Chemistry Communications 12 (2009) 201–203
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Inorganic Chemistry Communications journal homepage: www.elsevier.com/locate/inoche
A two-dimensional copper polymer constructed from rod-shaped ferromagnetic secondary building units Zhao-Xi Wang a,*, Ming-Xing Li a, Min Shao b, Hong-Ping Xiao c,* a
Department of Chemistry, College of Science, Shanghai University, Shanghai 200444, PR China Instrumental Analysis and Research Center, Shanghai University, Shanghai 200444, PR China c School of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325027, PR China b
a r t i c l e
i n f o
Article history: Received 20 November 2008 Accepted 17 December 2008 Available online 25 December 2008 Keywords: Azide–copper Crystal structure Magnetic properties SBUs
a b s t r a c t On the basis of rod-shaped secondary building units (SBUs), a novel two-dimensional (2D) azide–copper polymer, [Cu3(N3)4(anol)2]1 (1; anol = aminoethanol), was synthesized and structurally characterized. Complex 1 is a neutral 2D coordination network consisting of trinuclear copper(II) clusters [Cu3(N3)4(anol)2] connected with the bridge of end-end (EE) azide group. Magnetic data analysis shows that a metamagnetic behavior is observed for 1 which is associated with significant ferromagnetic coupling intracluster over 4 K. Ó 2009 Elsevier B.V. All rights reserved.
The coordination polymers construction of secondary building units (SBUs) have drawn more attention due to their various topologies of structures and fascinating properties, such as porosity, nonlinear optical property, and magnetism [1–5]. Since the SBUs have triangular, square, tetrahedral, and octahedral building-block geometries, which can show different spatial configurations and maintain their structural integrity throughout the self-assembly process, a variety of multi-dimensional coordination geometries can be found in the crystal structure of their complexes, i.e., onedimensional (1D) [6], 2D [7–11], and 3D [12–17]. Thus it was implicated that the design of high-dimensional magnetic systems might be realized starting from magnetic SBUs. Indeed, Miyasaka group obtained a long-range ferrimagnetic ordering 3D polymers used Mn4 single-molecule magnet as the SBUs [18] and a few of magnetic compounds constructed from well-defined ferromagnetic precursors were subsequently reported [19,20]. Consequently, this strategy may provide new insights to the design of new magnetic materials by using magnetic SBUs to create bulk magnets. As we have known, some derivatives of aminoethanol reacting with copper(II) ions may easily produce ferromagnetic copper clusters [21–24]. In addition, azide ligand has been playing an important role in the design and synthesis of magnetic materials because azide bridge can mediate strong coupling between mag-
* Corresponding authors. Tel.: +86 21 66132670; fax: +86 21 66132797 (Z.-X. Wang). E-mail addresses: [email protected] (Z.-X. Wang), [email protected] (H.-P. Xiao). 1387-7003/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2008.12.014
netic centres [25–29]. Therefore, in order to obtain the compounds with strong magnetic exchange between copper clusters, a twodimensional polymer composed of rod-shaped Cu3 SBUs directly linked by the azide ligands, [Cu3(N3)4(anol)2]1 (1; anol = aminoethanol) was prepared. Herein, we reported the synthesis, crystal structure and magnetic properties of 1. The complex 1 was prepared by reaction of Cu(NO3)2 3H2O (48.5 mg, 0.2 mmol), aminoethanol (6.1 mg, 0.1 mmol) and NaN3 (130.4 mg, 2 mmol) in methanol and water mixture for one month, giving brown crystals in a yield of 40% (based on Cu). Anal. Calcd (%) for C4H12Cu3N14O2: C, 10.03; H, 2.53; N, 40.95. Found: C, 10.00; H, 2.65; N, 40.89. Selected IR data (KBr, cm1): m = 2012, 2031 and 2102 for the azide group. X-ray structural analysis [30] revealed that complex 1 is a neutral, two-dimensional coordination network based on trinuclear copper clusters [Cu3(N3)4(anol)2] joined by end-end (EE) azide groups. As shown in Fig. 1, the basic unit contains three Cu(II) metal centres arranged in linear that are bridged by two end-on (EO) azide ligands and two l2-oxygen atom of two aminoethanol. In the unit, the Cu1 is five-coordination with a distorted square-pyramidal geometry, where one l2-oxygen atoms and a nitrogen atom of two aminoethanol with two nitrogen atom of two EO azide groups form the basal plane, while a nitrogen atom of one EE azide bridge occupies the apical position. The Cu2 is four-coordination described as distorted square planar. The basal Cu–N bond lengths are in the range of 1.972–2.005 Å which is identical to Cu–azide compounds [32–35], and the apical Cu–N bond lengths is 2.442(3) Å. The Cu–O bond lengths are 1.9535(19) Å and 1.9412(18) Å, respectively. As the key parameter for magnetic cou-
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Fig. 1. View of the trinuclear copper structure of 1 showing ellipsoids at the 50% probability level. Hydrogen atoms have been omitted for clarity. Selected bond lengths (Å) and angles (°): Cu(1)–N(1) 2.005(2), Cu(1)–N(4) 1.972(3), Cu(1)–N(7) 1.978(2), Cu(1)–O(1) 1.9535(19), Cu(2)–N(1) 2.000(2), Cu(2)–O(1) 1.9412(18), Cu(2)–N(1)#1 2.000(2), Cu(2)–O(1)#1 1.9412(18), O(1)–Cu(1)–N(1) 80.03(9), O(1)–Cu(2)–N(1) 80.45(9), Cu(1)–O(1)–Cu(2) 100.49(8), Cu(1)–N(1)–Cu(2) 96.79(10). Symmetry #1 x + 2, y + 1, z + 1.
pling between metal centres, the Cu(1)–N(1)–Cu(2) and Cu(1)– O(1)–Cu(2) bond angles are 96.79(10)° and 100.49(8)°. The central copper(II) atom Cu2 connected the two terminal copper(II) (Cu1 and Cu1A) by double bridges of EO azide and l2-O atoms to generate a linear trinuclear clusters. The clusters act as rod-shaped SBUs and are joined into a 2D network by the EE azide groups in the bc plane (Fig. 2). Each rod-shaped unit is directly connected to four neighboring rods through four EE azide bridges. The Cu Cu separation through the EO azide bridges is 2.994 Å, and through the EE bridges is 5.011 Å. In the solid state, the 2D network extend to three-dimension architecture by four hydrogen bonds of N7– H7A O1 (symmetry: x, y + 3/2, z 1/2), N7–H7B N4 (symmetry: x + 2, y + 1, z), C2–H2A N3 (symmetry: x 1, y, z 1), and C2–H2B N3 (symmetry: x 1, y + 3/2, z 1/2). Magnetic susceptibility measurements of the crystalline sample of 1 was carried out on a Quantum Design MPMS-XL7 SQUID magnetometer in an applied magnetic field of 2 KOe over the temperature range 1.8–300 K. For 1, the vMT versus T plot is shown in Fig. 3. At room-temperature vMT value is 1.36 emu K mol1, slightly larger than the spin-only value of 1.24 emu K mol1 based on uncoupled Cu3 unit (SCu = 1/2 and assuming gCu = 2.1). When the system is cooled, the vMT value gradually increases and then rapidly below 50 K up to a maximum of 3.16 emu K mol1 at 4 K, indicating ferromagnetic coupling between CuII ions with a ground
Fig. 2. Projection of the 2D network formed by rod-shaped SBUs (cyan rob) in the bc plane. Aminoethanol ligands, and EO azide groups have been omitted for clarity.
Fig. 3. Temperature dependence of magnetic susceptibilities of 1 in an applied field of 2 KOe. Solid line represents the best fit of the data.
state spin ST = 3/2. Below 4 K, vMT shows a sharp drop to 0.96 emu K mol1 at 1.8 K, suggesting antiferromagnetic coupling between Cu3 units. An additional evidence of ST = 3/2 is observed from the field dependence of magnetization at 1.8 K (Fig. 4), where the saturation magnetization is 3.04 Nb mol1 at 7 T. The sigmoidal shape of the magnetization curve is the signature of metamagnetic behavior [36,37] which is confirmed by the low-temperature M versus T plots at various fields in the inset of Fig. 4. To estimate the magnetic coupling interaction between CuII ions and the intermolecular interaction, the magnetic data can be simulated by the isotropic spin Hamiltonian H = 2J(SCu1SCu2 + SCu2SCu1A), where J is the coupling constants mediated by double bridges of EO azide and l2-O atoms in cluster. When mean field correction was taken into account, the van Vleck equation can be written as follows:
Ng 2 b2 1 þ e2J=kT þ 10e3J=kT ; 4kT 1 þ e2J=kT þ 2e3J=kT 0 2 2 ¼ v=½1 ð2zj =Ng b Þv:
v¼
ð1Þ
vM
ð2Þ
Fig. 4. Field dependence of the magnetization for 1 at 1.8 K. The inset presents plot of M–T in low-temperature at various fields.
Z.-X. Wang et al. / Inorganic Chemistry Communications 12 (2009) 201–203
With this rough model, the calculated results in the temperature range from 5 to 300 K give: g = 2.18(5), J = 10.6(4) cm1, and P P zj0 = 0.38(1) cm1 with R = [(vMT)calc (vMT)obs]2/ (vMT)obs2 = 4 5.2 10 . The magnetic data are reasonable and can be rationalized in light of the structure. In compound 1, Cu1 and Cu2 provide their d(x2 y2) magnetic orbitals extended along the basal plane of the copper ions. The N1 atom of EO bridges occupies equatorial coordination position to form ferromagnetic couplings. According to the density functional calculations, the coupling parameter J is involved in the structural parameters, such as the Cu(1)–N(1)– Cu(2) angle and the bond length of Cu–Nazide. At the same time, the oxygen bridges in the basal planes mediate the antiferromagnetic exchange interaction due to the Cu(1)–O(1)–Cu(2) bond angles larger than 98° [38–40]. So the J value is actually a sum of two contributions from EO azide bridge and oxygen bridge, respectively, which has also been reported [41]. Because the axial Cu–N bonds between trinuclear entities are long with 2.442(3) Å, the mean field correction (zJ0 ) is very weak. In summary, we have described the syntheses, single crystal structure and low-temperature magnetic behavior of the azide– copper complex 1. Complex 1 is a novel 2D azide–copper polymer constructed by end-end model azide bridges between rod-shaped Cu3 SBUs. A metamagnetic behavior is observed for 1 which is associated with significant ferromagnetic coupling intracluster over 4 K. Acknowledgements This work was supported by Excellent Youth Teachers Foundation of Shanghai Municipal Education Committee and the Innovation Foundation of Shanghai University. Appendix A. Supplementary material CCDC 700730 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/ data_request/cif. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.inoche.2008. 12.014. References [1] O.M. Yaghi, H. Li, C. Davis, D. Richardson, T.L. Groy, Acc. Chem. Res. 31 (1998) 474–484. [2] M. Eddaoudi, D.B. Moler, H. Li, B. Chen, T.M. Reineke, M. O’Keeffe, O.M. Yaghi, Acc. Chem. Res. 34 (2001) 319–330. [3] O.M. Yaghi, M. O’Keeffe, N.W. Ockwig, H.K. Chae, M. Eddaoudi, J. Kim, Nature 423 (2003) 705–714. [4] N.W. Ockwig, O. Delgado-Friedrichs, M. O’Keeffe, O.M. Yaghi, Acc. Chem. Res. 38 (2005) 176–182. [5] A. Escuer, F.A. Mautner, M.A.S. Goher, M.A.M. Abu-Youssef, R. Vicente, Chem. Commun. (2005) 605–607. [6] J. Yoo, W. Wernsdorfer, E.-C. Yang, M. Nakano, A.L. Rheigold, D.N. Hendrickson, Inorg. Chem. 44 (2005) 3377–3379.
203
[7] B. Moulton, J. Lu, M.J. Zaworotko, J. Am. Chem. Soc. 123 (2001) 9224– 9225. [8] X. Xue, X.-S. Wang, R.-G. Xiong, X.-Z. You, B.F. Abrahams, C.-M. Che, H.-X. Ju, Angew. Chem., Int. Ed. 41 (2002) 2944–2946. [9] J.-J. Zhang, S.-Q. Xia, T.-L. Sheng, S.-M. Hu, G. Leibeling, F. Meyer, X.-T. Wu, S.-C. Xiang, R.-B. Fu, Chem. Commun. (2004) 1186–1187. [10] T.E. Vos, J.S. Miller, Angew. Chem., Int. Ed. 44 (2005) 2416–2419. [11] R.-Q. Zou, H. Sakurai, S. Han, R.-Q. Zhong, Q. Xu, J. Am. Chem. Soc. 129 (2007) 8402–8403. [12] B.-Q. Ma, D.-S. Zhang, S. Gao, T.-Z. Jin, C.-H. Yan, G.-X. Xu, Angew. Chem., Int. Ed. 39 (2000) 3644–3646. [13] C. Livage, N. Guillou, J. Chaigneau, P. Rabu, M. Drillon, G. Férey, Angew. Chem., Int. Ed. 44 (2005) 6488–6491. [14] A.G. Wong-Foy, O. Lebel, A.J. Matzger, J. Am. Chem. Soc. 129 (2007) 15740– 15741. [15] H. Chun, J. Am. Chem. Soc. 130 (2008) 800–801. [16] A.J. Cairns, J.A. Perman, L. Wojtas, V.Ch. Kravtsov, M.H. Alkordi, M. Eddaoudi, M.J. Zaworotko, J. Am. Chem. Soc. 130 (2008) 1560–1561. [17] F. Nouar, J.F. Eubank, T. Bousquet, L. Wojtas, M.J. Zaworotko, M. Eddaoudi, J. Am. Chem. Soc. 130 (2008) 1833–1835. [18] H. Miyasaka, K. Nakata, K. Sugiura, M. Yamashita, R. Clerac, Angew. Chem., Int. Ed. 43 (2004) 707–711. [19] H. Miyasaka, K. Nakata, L. Lecren, C. Coulon, Y. Nakazawa, T. Fujisaki, K. Sugiura, M. Yamashita, R. Clerac, J. Am. Chem. Soc. 128 (2006) 3770–3783. [20] Z.-G. Gu, J.-L. Zuo, X.-Z. You, Dalton Trans. (2007) 4067–4072. [21] L. Merz, W. Haase, G. Keller, Ber. Bunsenges. Phys. Chem. 80 (1976) 305– 311. [22] N. Matsumoto, I. Ueda, Y. Nishida, S. Kida, Bull. Chem. Soc. Jpn. 49 (1976) 1308–1312. [23] R. Mergehenn, L. Merz, W. Haase, J. Chem. Soc., Dalton Trans. (1980) 1703– 1709. [24] Z.-X. Wang, X.-L. Li, B.-L. Liu, H. Tokoro, P. Zhang, Y. Song, S. Ohkoshi, K. Hashimoto, X.-Z. You, Dalton Trans. (2008) 2103–2106. [25] J. Ribas, A. Escuer, M. Monfort, R. Vicente, R. Cortés, L. Lezama, T. Rojo, Coord. Chem. Rev. 195 (1999) 1027–1068. [26] Z. Shen, J.-L. Zuo, S. Gao, Y. Song, C.-M. Che, H.-K. Fun, X.-Z. You, Angew. Chem., Int. Ed. 39 (2000) 3633–3635. [27] T.K. Maji, P.S. Mukherjee, N.R. Chaudhuri, G. Mostafa, T. Mallah, J. CanoBoquera, Chem. Commun. (2001) 1012–1013. [28] E.-Q. Gao, Y.-F. Yue, S.-Q. Bai, Z. He, C.-H. Yan, J. Am. Chem. Soc. 126 (2004) 1419–1429. [29] X.-Y. Wang, Z.-M. Wang, S. Gao, Chem. Commun. (2008) 281–294. [30] Crystal data for 1: C4H12Cu3N14O2, Mr = 478.93, monoclinic, space group P21/c, a = 8.5271(11), b = 11.4466(15), c = 8.0594(10) Å, b = 115.296(2)°, V = 711.22(16) Å3, Z = 2, Dc = 2.236 g cm3, l (Mo Ka) = 4.480 mm1, F(0 0 0) = 474, R1 = 0.0283, wR2 = 0.0676 for 1623 unique reflections and 106 parameters, S = 1.02. Data were collected on a Bruker SMART Apex-II CCD area detector. The structure was solved using direct methods with SHELXTL program [31] and refined on F2 by full-matrix least squares techniques. All non-hydrogen atoms were refined anisotropically, and hydrogen atoms were located and included at their calculated positions. [31] Bruker, SMART, SAINT, SADABS and SHELXTL, Bruker AXS Inc., Madison, WI, USA, 2000. [32] P.S. Mukherjee, S. Dalai, G. Mostafa, T.-H. Lu, E. Rentschler, N.R. Chaudhuri, New J. Chem. 25 (2001) 1203–1207. [33] J.D. Woodward, R.V. Backov, K.A. Abboud, D. Dai, H.-J. Koo, M.-H. Whangbo, M.W. Meisel, D.R. Talham, Inorg. Chem. 44 (2005) 638–648. [34] Y.-Z. Zhang, H.-Y. Wei, F. Pan, Z.-M. Wang, Z.-D. Chen, S. Gao, Angew. Chem., Int. Ed. 44 (2005) 5841–5846. [35] T. Liu, Y.-F. Yang, Z.-M. Wang, S. Gao, Chem. Asian J. 3 (2008) 950–957. [36] L. Toma, R. Lescouëzec, J. Vaissermann, F.S. Delgado, C. Ruiz-Pérez, R. Carrasco, J. Cano, F. Lloret, M. Julve, Chem. Eur. J. 10 (2004) 6130–6145. [37] J.H. Yoon, H.C. Kim, C.S. Hong, Inorg. Chem. 44 (2005) 7714–7716. [38] V.H. Crawford, H.W. Richardson, J.R. Wasson, D.J. Hodgson, W.E. Hatfield, Inorg. Chem. 15 (1976) 2107–2110. [39] E. Ruiz, P. Alemany, S. Alvarez, J. Cano, J. Am. Chem. Soc. 119 (1997) 1297– 1303. [40] E. Ruiz, J. Cano, S. Alvarez, P. Alemany, M. Verdaguer, Phys. Rev. B 61 (2000) 54–57. [41] V. Mckee, S.S. Tandon, J. Chem. Soc., Dalton Trans. (1991) 221–230.
Contents lists available at ScienceDirect
Inorganic Chemistry Communications journal homepage: www.elsevier.com/locate/inoche
A two-dimensional copper polymer constructed from rod-shaped ferromagnetic secondary building units Zhao-Xi Wang a,*, Ming-Xing Li a, Min Shao b, Hong-Ping Xiao c,* a
Department of Chemistry, College of Science, Shanghai University, Shanghai 200444, PR China Instrumental Analysis and Research Center, Shanghai University, Shanghai 200444, PR China c School of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325027, PR China b
a r t i c l e
i n f o
Article history: Received 20 November 2008 Accepted 17 December 2008 Available online 25 December 2008 Keywords: Azide–copper Crystal structure Magnetic properties SBUs
a b s t r a c t On the basis of rod-shaped secondary building units (SBUs), a novel two-dimensional (2D) azide–copper polymer, [Cu3(N3)4(anol)2]1 (1; anol = aminoethanol), was synthesized and structurally characterized. Complex 1 is a neutral 2D coordination network consisting of trinuclear copper(II) clusters [Cu3(N3)4(anol)2] connected with the bridge of end-end (EE) azide group. Magnetic data analysis shows that a metamagnetic behavior is observed for 1 which is associated with significant ferromagnetic coupling intracluster over 4 K. Ó 2009 Elsevier B.V. All rights reserved.
The coordination polymers construction of secondary building units (SBUs) have drawn more attention due to their various topologies of structures and fascinating properties, such as porosity, nonlinear optical property, and magnetism [1–5]. Since the SBUs have triangular, square, tetrahedral, and octahedral building-block geometries, which can show different spatial configurations and maintain their structural integrity throughout the self-assembly process, a variety of multi-dimensional coordination geometries can be found in the crystal structure of their complexes, i.e., onedimensional (1D) [6], 2D [7–11], and 3D [12–17]. Thus it was implicated that the design of high-dimensional magnetic systems might be realized starting from magnetic SBUs. Indeed, Miyasaka group obtained a long-range ferrimagnetic ordering 3D polymers used Mn4 single-molecule magnet as the SBUs [18] and a few of magnetic compounds constructed from well-defined ferromagnetic precursors were subsequently reported [19,20]. Consequently, this strategy may provide new insights to the design of new magnetic materials by using magnetic SBUs to create bulk magnets. As we have known, some derivatives of aminoethanol reacting with copper(II) ions may easily produce ferromagnetic copper clusters [21–24]. In addition, azide ligand has been playing an important role in the design and synthesis of magnetic materials because azide bridge can mediate strong coupling between mag-
* Corresponding authors. Tel.: +86 21 66132670; fax: +86 21 66132797 (Z.-X. Wang). E-mail addresses: [email protected] (Z.-X. Wang), [email protected] (H.-P. Xiao). 1387-7003/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2008.12.014
netic centres [25–29]. Therefore, in order to obtain the compounds with strong magnetic exchange between copper clusters, a twodimensional polymer composed of rod-shaped Cu3 SBUs directly linked by the azide ligands, [Cu3(N3)4(anol)2]1 (1; anol = aminoethanol) was prepared. Herein, we reported the synthesis, crystal structure and magnetic properties of 1. The complex 1 was prepared by reaction of Cu(NO3)2 3H2O (48.5 mg, 0.2 mmol), aminoethanol (6.1 mg, 0.1 mmol) and NaN3 (130.4 mg, 2 mmol) in methanol and water mixture for one month, giving brown crystals in a yield of 40% (based on Cu). Anal. Calcd (%) for C4H12Cu3N14O2: C, 10.03; H, 2.53; N, 40.95. Found: C, 10.00; H, 2.65; N, 40.89. Selected IR data (KBr, cm1): m = 2012, 2031 and 2102 for the azide group. X-ray structural analysis [30] revealed that complex 1 is a neutral, two-dimensional coordination network based on trinuclear copper clusters [Cu3(N3)4(anol)2] joined by end-end (EE) azide groups. As shown in Fig. 1, the basic unit contains three Cu(II) metal centres arranged in linear that are bridged by two end-on (EO) azide ligands and two l2-oxygen atom of two aminoethanol. In the unit, the Cu1 is five-coordination with a distorted square-pyramidal geometry, where one l2-oxygen atoms and a nitrogen atom of two aminoethanol with two nitrogen atom of two EO azide groups form the basal plane, while a nitrogen atom of one EE azide bridge occupies the apical position. The Cu2 is four-coordination described as distorted square planar. The basal Cu–N bond lengths are in the range of 1.972–2.005 Å which is identical to Cu–azide compounds [32–35], and the apical Cu–N bond lengths is 2.442(3) Å. The Cu–O bond lengths are 1.9535(19) Å and 1.9412(18) Å, respectively. As the key parameter for magnetic cou-
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Z.-X. Wang et al. / Inorganic Chemistry Communications 12 (2009) 201–203
Fig. 1. View of the trinuclear copper structure of 1 showing ellipsoids at the 50% probability level. Hydrogen atoms have been omitted for clarity. Selected bond lengths (Å) and angles (°): Cu(1)–N(1) 2.005(2), Cu(1)–N(4) 1.972(3), Cu(1)–N(7) 1.978(2), Cu(1)–O(1) 1.9535(19), Cu(2)–N(1) 2.000(2), Cu(2)–O(1) 1.9412(18), Cu(2)–N(1)#1 2.000(2), Cu(2)–O(1)#1 1.9412(18), O(1)–Cu(1)–N(1) 80.03(9), O(1)–Cu(2)–N(1) 80.45(9), Cu(1)–O(1)–Cu(2) 100.49(8), Cu(1)–N(1)–Cu(2) 96.79(10). Symmetry #1 x + 2, y + 1, z + 1.
pling between metal centres, the Cu(1)–N(1)–Cu(2) and Cu(1)– O(1)–Cu(2) bond angles are 96.79(10)° and 100.49(8)°. The central copper(II) atom Cu2 connected the two terminal copper(II) (Cu1 and Cu1A) by double bridges of EO azide and l2-O atoms to generate a linear trinuclear clusters. The clusters act as rod-shaped SBUs and are joined into a 2D network by the EE azide groups in the bc plane (Fig. 2). Each rod-shaped unit is directly connected to four neighboring rods through four EE azide bridges. The Cu Cu separation through the EO azide bridges is 2.994 Å, and through the EE bridges is 5.011 Å. In the solid state, the 2D network extend to three-dimension architecture by four hydrogen bonds of N7– H7A O1 (symmetry: x, y + 3/2, z 1/2), N7–H7B N4 (symmetry: x + 2, y + 1, z), C2–H2A N3 (symmetry: x 1, y, z 1), and C2–H2B N3 (symmetry: x 1, y + 3/2, z 1/2). Magnetic susceptibility measurements of the crystalline sample of 1 was carried out on a Quantum Design MPMS-XL7 SQUID magnetometer in an applied magnetic field of 2 KOe over the temperature range 1.8–300 K. For 1, the vMT versus T plot is shown in Fig. 3. At room-temperature vMT value is 1.36 emu K mol1, slightly larger than the spin-only value of 1.24 emu K mol1 based on uncoupled Cu3 unit (SCu = 1/2 and assuming gCu = 2.1). When the system is cooled, the vMT value gradually increases and then rapidly below 50 K up to a maximum of 3.16 emu K mol1 at 4 K, indicating ferromagnetic coupling between CuII ions with a ground
Fig. 2. Projection of the 2D network formed by rod-shaped SBUs (cyan rob) in the bc plane. Aminoethanol ligands, and EO azide groups have been omitted for clarity.
Fig. 3. Temperature dependence of magnetic susceptibilities of 1 in an applied field of 2 KOe. Solid line represents the best fit of the data.
state spin ST = 3/2. Below 4 K, vMT shows a sharp drop to 0.96 emu K mol1 at 1.8 K, suggesting antiferromagnetic coupling between Cu3 units. An additional evidence of ST = 3/2 is observed from the field dependence of magnetization at 1.8 K (Fig. 4), where the saturation magnetization is 3.04 Nb mol1 at 7 T. The sigmoidal shape of the magnetization curve is the signature of metamagnetic behavior [36,37] which is confirmed by the low-temperature M versus T plots at various fields in the inset of Fig. 4. To estimate the magnetic coupling interaction between CuII ions and the intermolecular interaction, the magnetic data can be simulated by the isotropic spin Hamiltonian H = 2J(SCu1SCu2 + SCu2SCu1A), where J is the coupling constants mediated by double bridges of EO azide and l2-O atoms in cluster. When mean field correction was taken into account, the van Vleck equation can be written as follows:
Ng 2 b2 1 þ e2J=kT þ 10e3J=kT ; 4kT 1 þ e2J=kT þ 2e3J=kT 0 2 2 ¼ v=½1 ð2zj =Ng b Þv:
v¼
ð1Þ
vM
ð2Þ
Fig. 4. Field dependence of the magnetization for 1 at 1.8 K. The inset presents plot of M–T in low-temperature at various fields.
Z.-X. Wang et al. / Inorganic Chemistry Communications 12 (2009) 201–203
With this rough model, the calculated results in the temperature range from 5 to 300 K give: g = 2.18(5), J = 10.6(4) cm1, and P P zj0 = 0.38(1) cm1 with R = [(vMT)calc (vMT)obs]2/ (vMT)obs2 = 4 5.2 10 . The magnetic data are reasonable and can be rationalized in light of the structure. In compound 1, Cu1 and Cu2 provide their d(x2 y2) magnetic orbitals extended along the basal plane of the copper ions. The N1 atom of EO bridges occupies equatorial coordination position to form ferromagnetic couplings. According to the density functional calculations, the coupling parameter J is involved in the structural parameters, such as the Cu(1)–N(1)– Cu(2) angle and the bond length of Cu–Nazide. At the same time, the oxygen bridges in the basal planes mediate the antiferromagnetic exchange interaction due to the Cu(1)–O(1)–Cu(2) bond angles larger than 98° [38–40]. So the J value is actually a sum of two contributions from EO azide bridge and oxygen bridge, respectively, which has also been reported [41]. Because the axial Cu–N bonds between trinuclear entities are long with 2.442(3) Å, the mean field correction (zJ0 ) is very weak. In summary, we have described the syntheses, single crystal structure and low-temperature magnetic behavior of the azide– copper complex 1. Complex 1 is a novel 2D azide–copper polymer constructed by end-end model azide bridges between rod-shaped Cu3 SBUs. A metamagnetic behavior is observed for 1 which is associated with significant ferromagnetic coupling intracluster over 4 K. Acknowledgements This work was supported by Excellent Youth Teachers Foundation of Shanghai Municipal Education Committee and the Innovation Foundation of Shanghai University. Appendix A. Supplementary material CCDC 700730 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/ data_request/cif. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.inoche.2008. 12.014. References [1] O.M. Yaghi, H. Li, C. Davis, D. Richardson, T.L. Groy, Acc. Chem. Res. 31 (1998) 474–484. [2] M. Eddaoudi, D.B. Moler, H. Li, B. Chen, T.M. Reineke, M. O’Keeffe, O.M. Yaghi, Acc. Chem. Res. 34 (2001) 319–330. [3] O.M. Yaghi, M. O’Keeffe, N.W. Ockwig, H.K. Chae, M. Eddaoudi, J. Kim, Nature 423 (2003) 705–714. [4] N.W. Ockwig, O. Delgado-Friedrichs, M. O’Keeffe, O.M. Yaghi, Acc. Chem. Res. 38 (2005) 176–182. [5] A. Escuer, F.A. Mautner, M.A.S. Goher, M.A.M. Abu-Youssef, R. Vicente, Chem. Commun. (2005) 605–607. [6] J. Yoo, W. Wernsdorfer, E.-C. Yang, M. Nakano, A.L. Rheigold, D.N. Hendrickson, Inorg. Chem. 44 (2005) 3377–3379.
203
[7] B. Moulton, J. Lu, M.J. Zaworotko, J. Am. Chem. Soc. 123 (2001) 9224– 9225. [8] X. Xue, X.-S. Wang, R.-G. Xiong, X.-Z. You, B.F. Abrahams, C.-M. Che, H.-X. Ju, Angew. Chem., Int. Ed. 41 (2002) 2944–2946. [9] J.-J. Zhang, S.-Q. Xia, T.-L. Sheng, S.-M. Hu, G. Leibeling, F. Meyer, X.-T. Wu, S.-C. Xiang, R.-B. Fu, Chem. Commun. (2004) 1186–1187. [10] T.E. Vos, J.S. Miller, Angew. Chem., Int. Ed. 44 (2005) 2416–2419. [11] R.-Q. Zou, H. Sakurai, S. Han, R.-Q. Zhong, Q. Xu, J. Am. Chem. Soc. 129 (2007) 8402–8403. [12] B.-Q. Ma, D.-S. Zhang, S. Gao, T.-Z. Jin, C.-H. Yan, G.-X. Xu, Angew. Chem., Int. Ed. 39 (2000) 3644–3646. [13] C. Livage, N. Guillou, J. Chaigneau, P. Rabu, M. Drillon, G. Férey, Angew. Chem., Int. Ed. 44 (2005) 6488–6491. [14] A.G. Wong-Foy, O. Lebel, A.J. Matzger, J. Am. Chem. Soc. 129 (2007) 15740– 15741. [15] H. Chun, J. Am. Chem. Soc. 130 (2008) 800–801. [16] A.J. Cairns, J.A. Perman, L. Wojtas, V.Ch. Kravtsov, M.H. Alkordi, M. Eddaoudi, M.J. Zaworotko, J. Am. Chem. Soc. 130 (2008) 1560–1561. [17] F. Nouar, J.F. Eubank, T. Bousquet, L. Wojtas, M.J. Zaworotko, M. Eddaoudi, J. Am. Chem. Soc. 130 (2008) 1833–1835. [18] H. Miyasaka, K. Nakata, K. Sugiura, M. Yamashita, R. Clerac, Angew. Chem., Int. Ed. 43 (2004) 707–711. [19] H. Miyasaka, K. Nakata, L. Lecren, C. Coulon, Y. Nakazawa, T. Fujisaki, K. Sugiura, M. Yamashita, R. Clerac, J. Am. Chem. Soc. 128 (2006) 3770–3783. [20] Z.-G. Gu, J.-L. Zuo, X.-Z. You, Dalton Trans. (2007) 4067–4072. [21] L. Merz, W. Haase, G. Keller, Ber. Bunsenges. Phys. Chem. 80 (1976) 305– 311. [22] N. Matsumoto, I. Ueda, Y. Nishida, S. Kida, Bull. Chem. Soc. Jpn. 49 (1976) 1308–1312. [23] R. Mergehenn, L. Merz, W. Haase, J. Chem. Soc., Dalton Trans. (1980) 1703– 1709. [24] Z.-X. Wang, X.-L. Li, B.-L. Liu, H. Tokoro, P. Zhang, Y. Song, S. Ohkoshi, K. Hashimoto, X.-Z. You, Dalton Trans. (2008) 2103–2106. [25] J. Ribas, A. Escuer, M. Monfort, R. Vicente, R. Cortés, L. Lezama, T. Rojo, Coord. Chem. Rev. 195 (1999) 1027–1068. [26] Z. Shen, J.-L. Zuo, S. Gao, Y. Song, C.-M. Che, H.-K. Fun, X.-Z. You, Angew. Chem., Int. Ed. 39 (2000) 3633–3635. [27] T.K. Maji, P.S. Mukherjee, N.R. Chaudhuri, G. Mostafa, T. Mallah, J. CanoBoquera, Chem. Commun. (2001) 1012–1013. [28] E.-Q. Gao, Y.-F. Yue, S.-Q. Bai, Z. He, C.-H. Yan, J. Am. Chem. Soc. 126 (2004) 1419–1429. [29] X.-Y. Wang, Z.-M. Wang, S. Gao, Chem. Commun. (2008) 281–294. [30] Crystal data for 1: C4H12Cu3N14O2, Mr = 478.93, monoclinic, space group P21/c, a = 8.5271(11), b = 11.4466(15), c = 8.0594(10) Å, b = 115.296(2)°, V = 711.22(16) Å3, Z = 2, Dc = 2.236 g cm3, l (Mo Ka) = 4.480 mm1, F(0 0 0) = 474, R1 = 0.0283, wR2 = 0.0676 for 1623 unique reflections and 106 parameters, S = 1.02. Data were collected on a Bruker SMART Apex-II CCD area detector. The structure was solved using direct methods with SHELXTL program [31] and refined on F2 by full-matrix least squares techniques. All non-hydrogen atoms were refined anisotropically, and hydrogen atoms were located and included at their calculated positions. [31] Bruker, SMART, SAINT, SADABS and SHELXTL, Bruker AXS Inc., Madison, WI, USA, 2000. [32] P.S. Mukherjee, S. Dalai, G. Mostafa, T.-H. Lu, E. Rentschler, N.R. Chaudhuri, New J. Chem. 25 (2001) 1203–1207. [33] J.D. Woodward, R.V. Backov, K.A. Abboud, D. Dai, H.-J. Koo, M.-H. Whangbo, M.W. Meisel, D.R. Talham, Inorg. Chem. 44 (2005) 638–648. [34] Y.-Z. Zhang, H.-Y. Wei, F. Pan, Z.-M. Wang, Z.-D. Chen, S. Gao, Angew. Chem., Int. Ed. 44 (2005) 5841–5846. [35] T. Liu, Y.-F. Yang, Z.-M. Wang, S. Gao, Chem. Asian J. 3 (2008) 950–957. [36] L. Toma, R. Lescouëzec, J. Vaissermann, F.S. Delgado, C. Ruiz-Pérez, R. Carrasco, J. Cano, F. Lloret, M. Julve, Chem. Eur. J. 10 (2004) 6130–6145. [37] J.H. Yoon, H.C. Kim, C.S. Hong, Inorg. Chem. 44 (2005) 7714–7716. [38] V.H. Crawford, H.W. Richardson, J.R. Wasson, D.J. Hodgson, W.E. Hatfield, Inorg. Chem. 15 (1976) 2107–2110. [39] E. Ruiz, P. Alemany, S. Alvarez, J. Cano, J. Am. Chem. Soc. 119 (1997) 1297– 1303. [40] E. Ruiz, J. Cano, S. Alvarez, P. Alemany, M. Verdaguer, Phys. Rev. B 61 (2000) 54–57. [41] V. Mckee, S.S. Tandon, J. Chem. Soc., Dalton Trans. (1991) 221–230.