Mono-, bi-, and tri-nuclear η-cyclopentadienyl–rhodium complexes obtained from [Rh2(η-C5H5)2(µ-CO)(CO)2]. Crystal structure of [{Rh(η-C5H5)(µ-CO)}3]·0.24Me2CO

Abstract

The reactivity of [Rh₂(η-C₅H₅)₂(µ-CO)(CO)₂](1) towards SnCl₂, tetracyanoethylene, I₂, HgCl₂, PdCl₂, PtCl₂, and NMe₂CN has been examined. From the reaction of (1) with SnCl₂ the trimer [{Rh(η-C₅H₅)(CO)(SnCl₂)}₃] was obtained; for this compound is proposed a structure containing a six-membered ring with alternating rhodium and tin atoms. Tetracyanoethylene (tcne) reacts with (1) to give the mononuclear complex [Rh(η-C₅H₅)(CO)(tcne)]. HgCl₂ leaves unchanged the metallacyclic system R[graphic omitted]h and affords the adduct [{Rh(η-C₅H₅)(CO)(HgCl₂)}₂(µ-CO)]; in this reaction the complex (1) acts as a Lewis base. The known complex [Rh(η-C₅H₅)(CO)(I)₂] is the product of the reaction with iodine. Treatment of the compound (1) with PdCl₂ or PtCl₂, in acetone, leads in quantitative yields to [{Rh(η-C₅H₅)(µ-CO)}₃]·0.24Me₂CO, which is a new modification of the known trimer [{Rh(η-C₅H₅)(µ-CO)}₃]; the nature of the reaction intermediate is discussed. The crystal and molecular structure of the new crystalline form of the trimer has been determined by X-ray analysis. The complex crystallizes in the space group Pm1 in a cell of dimensions a= 12.815(2), c= 6.916(1)Å, and Z= 2. Using 549 unique reflections, the structure was refined to R= 0.022 and R′= 0.025. The molecular structure consists of trimeric units, [{Rh(η-C₅H₅)(µ-CO)}₃], with crystallographic 3m symmetry. The trimer [{Rh(η-C₅H₅)(µ-CO)}₃] was also obtained, as the only product, from the reaction of (1) with NMe₂CN.