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

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]·0.24Me 2CO, 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 P3m1 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.