Silver(I) tetraiodoethylene complexes with twisted olefin moiety

The reactions of silver perchlorate and tetraiodoethylene in different solv ents, namely, benzene and toluene, isolated two silver(I)-iodocarbon comple xes, [Ag(C2I4)(C6H6)(2)(ClO4)] (1) and [Ag(C2I4)(ClO4)] (2). Both compounds contain intact iodoalkenes which coordinate via sigma-donation of a haloge n lone pair and retain their carbon-iodine bonds. Owing to the participatio n of the benzene molecules in coordination, complex 1 is found to be a disc rete monomer in which the five-coordinate geometry of the silver ion is com prised of two benzene molecules, one C2I4 group and one perchlorate ion. In contrast, the unsaturated coordination environment of the metal ion in 2 i s filled by the second iodocarbon group leading to a two-dimensional framew ork. The coordinated tetraiodoethylene molecules involve severe twisting of the C=C double bond, causing the C=C stretching band to move to a lower fr equency. (C) 1999 Elsevier Science S.A. All rights reserved.