One-dimensional assemblies of dirhodium units bridged by N,N'-dicyanoquinonediimine ligands.

Polymeric assemblies consisting of metal ions coordinated to polycyanide ligands are of interest for their conducting and magnetic properties.1-5 Unusual behavior results from dπ-pπ interactions between open-shell metal ions and organic radicals as illustrated by the family of 3-D metals Cu(R,R′-DCNQI)2 (DCNQI ) N, N′-dicyanoquinone diimine).5 The presence of π-stacked columns of DCNQI radicals is an important component of the conducting pathway, but interactions through the metal-organic skeleton are essential for leading to the extraordinarily high metallic conductivities exhibited by these coordination polymers. Metal-metal bonded complexes of the secondand thirdrow transition series are excellent prospects for reactions with nitrile acceptor ligands because of the fact that (1) they possess diffuse d orbitals that can engage in back-donation with ligand pπ orbitals, (2) they possess HOMO/LUMO levels whose energies can be easily varied, and (3) they undergo redox as well as simple ligand substitution reactions. There are a number of papers in the current literature on the subject of linked metalmetal bonded structures,6-9 but only a few instances of polycyano-bridged systems have been reported.10-18 To our knowledge, there are five structurally characterized polymers: the 1-D chains cis-[Rh2(O2CCH3)4(TCNE)]∞, trans-[Rh2(O2CCH3)4(TCNE)]8, and [Mo2(O2CCF3)4(DM-DCNQI)]∞, the