Cation control of dimensionality in isothiocyanate coordination polymers constructed from conformationally flexible 3,3′-bipyridine tethers

Two isothiocyanate coordination polymers constructed from the conformationally flexible tethering ligand 3,3'-bipyridine (3,3'-bpy) and divalent metal cations have been prepared and characterized via single crystal X-ray diffraction, infrared spectroscopy and elemental analysis. [Co(NCS)(2)(3.3'-bPY)(2)] (1), wherein the isothiocyanate ligands are coordinated in a trans fashion, manifests stacked two-dimensional (2-D) rhomboid grid layered motifs. In contrast, [Ni(NCS)(2)(3,3'-bpy)(2)] (2) possesses a doubly interpenetrated adamantoid three-dimensional (3-D) network despite the presence of trans isothiocyanate ligands. Thus, a metal cation-based control of coordination polymer dimensionality has been revealed in this system, reflective of different donor dispositions allowed by the conformational flexibility of the exobidentate 3.3'-bpy ligand. The 3-D framework of 2 decomposes at a temperature similar to 40 degrees C higher than the 2-D network of 1. (c) 2007 Elsevier B.V. All rights reserved.