Highly Rare Ferromagnetic Interaction with the Cu(tetrahedron)-Cu(square)-Cu(tetrahedron) Mode Observed in A 2-Fold Interpenetrating Moganite Net Feng Luo, Yun-xia Che, and Ji-min Zheng*
CRYSTAL GROWTH & DESIGN 2009 VOL. 9, NO. 5 2047–2049
Department of Chemistry, Nankai UniVersity, Tianjin, China ReceiVed October 28, 2008; ReVised Manuscript ReceiVed March 15, 2009
ABSTRACT: Polymer 1, Cu3(µ2-OH)2(nic)4 (Hnic) isonic otinic acid), was prepared by the hydrothermal self-assembly of CuCl and Hnic in the presence of HClO4. The outstanding feature of it is the moganite matrix with 2-fold interpenetration built on two distinct copper nodes and ferromagnetic coupling pathway in the Cu(tetrahedron)-Cu(square)-Cu(tetrahedron) fashion. The study of the magnetic interactions in polynuclear metal complexes is playing a key role in the development of magnetochemistry. In the literature, extensive efforts have been devoted to magnetostructural research of d9 copper(II)-based complexes.1 Usually, the d9 copper(II) ion holds square, 4 + 1 pyramidal, 4 + 2 octahedral, and tetrahedral geometry, and these geometries cooperating with different inorganic or organic mediums generate various structures and succedent magnetic phenomena. The first magnetostructural correlation about one planar hydroxo-bridged copper(II) dimers was theoretically interpreted by active-electron approach reported by Hatfield and Hodgson, and succedent ab initio calculation reported by Daudey.2 In light of these theoretical interpretations and numerous experimental results, they deduced a linear correlation of J (cm-1) ) -74R(degrees of Cu-O-Cu) + 7270 between J and R to determine ferromagnetic or antiferromagnetic interaction and evaluate the interaction strength.2 And the crucial R value is 97.5° with the below rule: if R > 97.5°, then J > 0, ferromagnetic interaction; if R < 97.5°, then J < 0, antiferromagnetic interaction. At the same time, such Hatfield and Hodgson’s correlation can be also obtained via the natural and orthogonalized magnetic orbital approaches: for this hydroxobridged copper(II) dimers, each Cu(II) ions show the square geometry, thus their single magnetic orbital is b1 and the final magnetic interactions of J ) Jb1b1 depends on the R value. J is positive for R close to 90°, and becomes negative for R far from 90°.3 Thereby, it is believed that the Cu(II)-based magnetic chemistry can be easily forecasted through the above theory and experiential approximate. On the basis of the copper(II) geometry, the possible magnetic interactions of hydroxo-bridged copper compounds between Cu(II) ions are (a) Cu(square)-Cu(square), (b) Cu(square)-Cu(pyramid), (c) Cu(square)-Cu(octahedron), (d) Cu(square)-Cu(tetrahedron), (e) Cu(pyramid)-Cu(pyramid), (f) Cu(pyramid)-Cu(octahedron), (g) Cu(pyramid)-Cu(tetrahedron), (h) Cu(octahedron)-Cu(octahedron), (i) Cu(octahedron)-Cu(tetrahedron), (j) Cu(tetrahedron)-Cu(tetrahedron). On the basis of the natural and orthogonalized magnetic orbital approaches, the a, b, c, e, f, and h magnetic correlation is determined by J ) Jb1b1 that depends on the R values as discussed above; for the d, g, i, and j magnetic correlation, their single magnetic orbital is a1(dxy), a2(dyz), or b2(dzx) and the final magnetic interactions are J ) Ja1b1, Ja2b1, and Jb2b1, where all the Ja1b1, Ja2b1, and Jb2b1 terms are strictly positive, then ferromagnetic interactions are expected. In other words, these magnetic correlations are undependent on R values; the j magnetic correlation holds the single magnetic orbital of a1(dxy), a2(dyz), or b2(dzx) and corresponding magnetic interactions of Ja1a1, Ja1a2, Ja1b2, Ja2a2, Ja2b2, Jb2b2, where Ja1a1, Ja2a2, Jb2b2 is expected to be antiferromagnetic, whereas Ja1b2, * To whom correspondence should be addressed. Fax: 86-22-23502458. Tel: 86-22-23507950. E-mail:
[email protected].
Figure 1. View of the Cu3(µ2-OH)2(CO2)4 trimer.
Ja1a2, and Ja2b2 is viewed to be ferromagnetic, then the macroscopical magnetic behavior is determined by the final magnetic interactions. In the literature, the a, b, c, e f, h, and j magnetic correlations are common.3,4 By contrast, to the best of our knowledge, we are not aware of a precedent featuring the d, g, i, and j magnetic correlation. Herein, we report a new hydroxo-bridged copper polymer, Cu3(µ2OH)2(nic)4, that displays the first d, viz. Cu(square)-Cu(tetrahedron), magnetic correlation. In the presence of HClO4, polymer 1 was synthesized by the hydrothermal self-assembly of CuCl and Hnic in a 1:1 ratio.5 Additional experiments are also explored to confirm the relationship between produces of 1 and reaction conditions. Either replacement of the copper source from CuCl2, CuSO4, or Cu(NO3)2 or the absence of HClO4 will generate another compound.6 Thus, the copper source from CuCl and the presence of HClO4 is crucial for the formation of 1. Moreover, the phase purity of the bulk samples of 1 is confirmed by powder X-ray diffraction studies, see the Supporting Information. The single-crystal X-ray diffraction analysis suggests the P21/C space group for 1.7 As shown in Figure 1, Cu1 atoms located on the inversion center holds the position occupation of 0.5 and CuN2O2 square geometry, completed by two µ2-OH oxygens and two nic nitrogens; Cu2 corresponds to the CuO3N tetrahedral geometry, finished by one µ2-OH oxygen, two nic oxygens, and one nic nitrogen. The Cu-O bond lengths of 1.910(2)-1.989(2)Å are slightly shorter than the Cu-N bond lengths in the range of 2.012(3)-2.054(3)Å, because of the different atom radius of N, O atoms. The nic ligands adopt the linear coordinated mode with one N and one carboxylate O donor to ligate copper atoms.
10.1021/cg801208z CCC: $40.75 2009 American Chemical Society Published on Web 04/07/2009
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Figure 2. Schematic description of the moganite net built on tetrahedral and square copper nodes.
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Figure 4. Experimental (black) and simulated (red) χMT vs T and χM vs T plots of 1.
Scheme 1.
H ) -2J(SCu1Cu2 + SCu1Cu2A) +
xm )
{
βg(SCu1 + SCu2 + SCu2A)H
(1 - F) +
Figure 3. View of 2-fold interpenetrating moganite net.
For 1, the first outstanding structure feature is the linear Cu3(OH)2(CO2)4 trimer with each copper pairs only bridged by one OH- group. Within it, the two terminal copper ions show the tetrahedral geometry, whereas the middle copper ions is square coordinated. The Cu-Cu distance and Cu-O-Cu angles are Cu1-Cu2/3.27 Å and Cu1-O1-Cu2/116.62°, respectively. In the literature, only one 1D compound has a similar linear Cu3(OH)2(CO2)4 fragment;8 however, in it, each copper pair is bridged not only by one OH- group but also by one carboxylate. Moreover, all the copper ions in it are square-coordinated. Thus, it is clear that the present linear Cu3(OH)2(CO2)4 trimer is unique and unprecedented. Another outstanding structure feature is the moganite net with 2-fold interpenetration built on two distinct copper nodes. As shown in Figure 2, each linear nic ligand acts as linker, and then each copper ion becomes to be 4-connected node. And the 3D matrix can be easily constructed by connecting Cu nodes together, yielding a 4-connected net (Figure 2). The topology analysis via Topos40 program9 suggests moganite net with the (42 · 62 · 82)(4 · 64 · 84)2 topology symbol, where the ratio of two kinds of copper nodes is Cu(tetrahedron)/Cu(square) ) 2:1. Furthermore, two identical moganite nets interpenetrate each other (type Ia), as illustrated in Figure 3. As we know, moganite, a newly recognized mineral, is closely related to quartz and presents the second most abundant crystalline material in the Earth’s crust because of its considerable technological importance. The construction of such net is somewhat difficult, as it requires two distinct 4-connected nodes. Until now, only a few cases have been reported to adopt such a topology.10 In 2004, Loye and co-workers reported a highly rare moganite net built on two distinct copper nodes, although all the copper ions are octahedrally coordinated. In comparison, the copper ions in the
}
1 + exp(2J ⁄ kT) + 10exp(3J ⁄ kT) Ng β × 4k(T - θ) 1 + exp(2J ⁄ kT) + 2exp(3J ⁄ kT) 2 2
[
2 2
]
3Ng β F + TIP 4kT (1)
present case are four-coordinated and allow 2-fold interpenetration. In contrast to the reported moganite nets, the present one is the first (3d metal)-based moganite net with 2-fold interpenetration. Besides its outstanding structural features, the present one also holds unique and unprecedented magnetic properties. The temperature-dependent magnetic susceptibility data of polymer 1 were measured for crystal samples at an applied magnetic field of 2000 Oe in the temperature range of 2-300 K. The χMT value at room temperature is 0.96 cm3 mol-1 K, comparable with the expected value of 1.13 cm3 mol-1 K for three Cu(II) centers as isolated magnetic source. At 300-50 K, the χMT value increases from 0.96 to 1.05 cm3 mol-1 K, indicating the very weak ferromagnetic behavior. Below 50 K, the χMT value drops abruptly until 0.72 cm3 mol-1 K at 2 K, because of intermolecular antiferromagnetic interactions and/or other factors (such as zero field splitting). This weak ferromagnetic interactions can be further supported by the fitting of χM ) C/(T - θ) at 2-300 K with C )0.98 cm3 mol-1 K, θ ) +2.0 K. (Figure 4.) Obviously, the magnetic property of 1 can be treated as a linear trinuclear system mediated by OH- group. As the two terminal copper atoms are symmetry-related, then only one coupling constant, J, is involved. The best fitting at 2-300 K upon the Cu2-J-Cu1-J-Cu2 mode with the consideration of other factors (θ) gives J ) +0.71 cm-1, g )2.01, TIP ) 350 × 10-6 cm3 mol, θ ) -1.8 K, F ) 0.1, where J is a coupling constant, θ other factors, g Zeeman factor, TIP temperature-independent paramagnetism, and F paramagnetic impurities.3 The detailed Heisenberg Hamiltonian and the derivation of theoretical equations of magnetic susceptibility are listed in Scheme 1.3 Usually, as discussed above, the magnetic nature for Cu(II) ions mediated by OH- groups can be estimated by orthogonalized or natural magnetic orbital approach, as well as Goodenough-Kanamori rules.3,11 For the system containing the square, pyramidal, or octahedral Cu(II) ions, their interaction between pairs of magnetic orbital is Jb1b1, then the well-defined linear correlation between J and R, J ) -74R + 7270, reported by Hatfield and Hodgson, can be utilize to evaluate the magnetic nature and the interaction strength
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of magnetic orbital. In 1, this special trimer comprises one square and two tetrahedral Cu(II) ions and it belongs to the abovementioned d magnetic correlation. Then the ferromagnetic interactions within this Cu3(µ2-OH)2(CO2)4 trimer is expected, which is well-consistent with the experimental results. In conclusion, herein, a new topological framework is prepared by the hydrothermal self-assembly of CuCl and Hnic in the presence of HClO4. Notably, it holds two outstanding features: (a) it presents the first (3d metal)-based, 2-fold interpenetrating moganite net; (b) it shows the first d, viz. Cu(square)-Cu(tetrahedron), magnetic correlation.
Acknowledgment. This work was supported by the National Natural Science Foundation of China (50572040). Supporting Information Available: XRD studies (PDF) and crystal data in CIF format. This material is available free of charge via the Internet at http://pubs.acs.org.
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References (1) (a) Charlot, M. F.; Verdaguer, M.; Journaux, Y.; Loth, P. D.; Daudey, J. P. Inorg. Chem. 1984, 23, 3802. (b) Glerup, J.; Goodson, P. A.; Hodgson, D. J.; Michelsen, K. Inorg. Chem. 1995, 34, 6255. (c) Castillo, O.; Luque, A.; Julve, M.; Lloret, F.; Roman, P. Inorg. Chim. Acta 2001, 315, 9. (d) Castillo, O.; Luque, A.; Julve, M.; Lloret, F.; Roman, P. Inorg. Chem. Commun. 2001, 4, 350. (e) Pellaux, R.; Schmalle, H. W.; Huber, R.; Fischer, P.; Hauss, T.; Ouladdiaf, B.; Decurtins, S. Inorg. Chem. 1997, 36, 2301. (2) (a) Crawford, W. H.; Richardson, H. W.; Wasson, J. R.; Hodgson, D. J.; Hatfield, W. E. Inorg. Chem. 1976, 15, 2107. (b) de Loth, P.;
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Darudey, J. P.; Astheimer, H.; Walz, L.; Haase, W. J. Chem. Phys. 1985, 97, 4884. Kahn, O. Molecular Magnetism; Wiley-VCH: New York, 1993. (a) King, P.; Cle´rac, R.; Anson, C. E.; Coulon, C.; Powell, A. K. Inorg. Chem. 2003, 42, 3492. (b) Ruiz, R.; Alemany, P.; Alvarez, S.; Cano, J. J. Am. Chem. Soc. 1997, 119, 1297. An aqueous solution (8 mL) of CuCl (1mmol) and Hnic (1 mmol) with 0.5 mL of HClO4 (70%) was sealed in a Teflon reactor and heated at 200°C for 7 days, and then cooled to room temperature at 3°C/h. Subsequently, blue crystals were obtained in 85% yield based on Hnic. Element anal. (%) Calcd for 1: C, 40.42; H, 2.54; N, 7.85. Found: C, 40.51; H, 2.47; N, 7.68. Waizumi, K.; Takuno, M.; Fukushima, N.; Masuda, H. J. Coord. Chem. 1998, 44, 269. Crystallographic data for 1: C24H18Cu3N4O10, monoclinic, P2(1)/c, Z ) 2, T ) 298(2) K, a ) 5.9567(12) Å, b ) 20.497(4) Å, c ) 10.180(2) Å, β ) 111.70(3)°, S ) 1.119, R1 ) 0.0379, wR2 ) 0.101. Chen, H.-J.; Zhang, J.; Feng, W.-L.; Fu, M. Inorg. Chem. Commun. 2006, 9, 300. (a) Blatov, V. A.;http://www.topos.ssu.samara.ru/ (2006). (b) Blatov, V. A.; Shevchenko, A. P.; Serezhkin, V. N. J. Appl. Crystallogr. 2000, 33, 1193. (a) O’Keeffe, M.; Yaghi, O. M. Reticular Chemistry Structure Resource; Arizona State University: Tempe, AZ, 2005; http://okeeffews1.la.asu.edu/rcsr /home.htm. (b) Ramsden, S. J.; Robins, V.; Hungerford, S.; Hyde, S. T.epinet.anu.edu.au (2006). (c) Su, C.-Y.; Smith, M. D.; Goforth, A. M.; zur Loye, H.-C. Inorg. Chem. 2004, 43, 6881. (d) Zhang, L.; Li, Z.-J.; Qin, Y.-Y.; Zhang, J.; Cheng, J.K.; Yin, P.-X.; Yao, Y.-G. CrystEngComm 2008, 10, 655. (a) Goodenough, J. B. Phys. ReV. 1995, 100, 564. (b) Kanamori, J. J. Phys. Chem. Solids 1959, 10, 87.
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