L. Jones, L. O'Dea, Daniel A. Offermann
Jan 23, 2006
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Influential Citations
52
Citations
Journal
Polyhedron
Abstract
Abstract The 1-methylbenzotriazole ligand (1-Mebta) has been successfully incorporated into four new 1-D coordination polymers of general formula [MII(dca)2(1-Mebta)2] (M = Mn (1), Fe (2) and Cu (3)) and [CuII(tcm)2(1-Mebta)2] (4) containing the dicyanamide ( N ( CN ) 2 - , dca - ) or tricyanamide ( C ( CN ) 3 - , tcm - ) μ1,5-bridging ligands. Magnetic susceptibility measurements reveal weak antiferromagnetic interactions between the MII centres without any long-range order. Spin-Hamiltonian parameters (g = ±0.01, J = ±0.01) were obtained using a chain model; [MII(dca)2(1-Mebta)2] (Mn (1): g = 1.94, J = −0.15 cm−1, Fe (2): g = 2.17, J = −0.38 cm−1, and g = 2.18, J = −0.01 cm−1) in [CuII(tcm)2(1-Mebta)2] (4). To increase the dimensionality of these benzotriazole-based networks, two benzotriazole molecules were linked together via alkyl chains in the form of the 1,3-di(benzotriazol-1-yl)propane (dbtp) and 1,4-di(benzotriazol-1-yl)butane (dbtb) ligands and these have produced 1-D, 2-D and 3-D networks. The dbtp ligand yields a 1-D ‘step-like’ chain coordination polymer in [CuII(dca)2(dbtp)](5), where the dbtp ligands propagate the 1-D chains; a role normally carried out by bridging dca− ions. Reaction of the dbtp ligand with CoII increases the dimensionality by producing the α-Po related 3-D [CoII(dca)2(dbtp)] (7) network. Compound 7 consists of 2-D (4,4) connecting sheets, linked together by the bridging dbtp ligand. The NiII analogue [NiII(dca)2(dbtp)] (8) has also been synthesized in polycrystalline form and characterized by powder X-ray diffraction. Magnetic measurements on 7 indicate extremely weak antiferromagnetic exchange interactions between the CoII ions while [NiII(dca)2(dbtp)] (8) exhibits short range ferromagnetic coupling with best-fit parameters g = 2.13 and J = +0.24 cm−1. The synthesis of a 2-D (4,4) connected sheet [CuII(dca)2(dbtb)] (9) (where dbtb is 1,4-di(benzotriazol-1-yl)butane) illustrates how increasing the alkyl chain by one carbon length has dramatically changed the topology and dimensionality of the network. Magnetic susceptibility measurements reveal weak antiferromagnetic exchange coupling.