Dinuclear molybdenum complexes containing the novel μ,η1:3-AsS2 ligand: synthesis and molecular structure of [{Cp*2Mo2(CO)2As2S4}·2Cr(CO)5]·0.5CH2Cl2 (Cp*=C5Me5)

The reaction of [Cp*Mo(CO)3Cl] (Cp*=C5Me5) with K3AsS3 has been investigated under different conditions. At 56°C, the already known compounds [Cp*2Mo2S4] (2), [Cp*2Mo2As2S3] (3), and [Cp*2Mo2S4H2] (4) are formed along with [Cp*2Mo2(CO)2As2S4] (5). Reaction at 120°C only gives 2 and 3. Complex 5 was characterized by means of its bisadduct [{Cp*2Mo2(CO)2As2S4}·2Cr(CO)5] (6). An X-ray crystallographic study of 6 reveals the presence of two novel AsS2 ligands, bridging in a pseudoallylic manner two Mo atoms. The Cr(CO)5 fragments are coordinated to both the outer sulfur atoms. Thus, each AsS2 ligand in 6 acts as a seven-electron ligand.