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Synthesis, structure and magnetic properties of 3D interpenetrating nets of M(pyrazine)[Au(CN)2]2 (M=Cu, Ni, Co) supported by aurophilic interactions

2001; Elsevier BV; Volume: 20; Issue: 11-14 Linguagem: Inglês

10.1016/s0277-5387(01)00601-5

1873-3719

Daniel B. Leznoff, Bao-Yu Xue, Cecilia L. Stevens, Alan Storr, Robert C. Thompson, Brian O. Patrick,

Organic and Molecular Conductors Research

New inorganic coordination polymers of the form M(pyrazine)[Au(CN)2]2 (M=Cu (1); Ni (2); Co (3)) have been prepared and the copper(II) analogue structurally characterised. The X-ray analysis revealed two 3D interpenetrating α-polonium networks consisting of 1D chains of Cu–pyrazine units connected by [Au(CN)2] bridges. The two networks are connected via weak aurophilic interactions (AuAu: 3.4729(2) Å). Thermogravimetric analysis of all three compounds indicated the robust nature of these 3D systems, with decomposition beginning at 260 (1), 406 (2) and 360°C (3). The magnetic susceptibility of 1 shows a maximum in χM at 5.0 K; these data could be fitted to the theoretical expressions for either a 1D or a 2D Heisenberg antiferromagnetic array (J=−2.74 cm−1, g=2.32 and J=−3.45 cm−1, g=2.33, respectively). The magnetic susceptibility versus temperature data for 2 and 3 showed effects primarily associated with single-ion zero-field splitting; any weak antiferromagnetic coupling in these systems is very weak and hence was not quantified. Although the aurophilic interactions between the [Au(CN)2] units may positively influence both the formation of an interpenetrating structure and its subsequent thermal stability, the incorporation of anionic [Au(CN)2] units into M(pyrazine) systems does not seem to significantly increase magnetic interactions.