Crystal structures of trans-acetyldicarbonyl(η5-cyclopentadienyl)(dimethylphenylphosphane)molybdenum(II) and trans-acetyldicarbonyl(η5-cyclopentadienyl)(ethyldiphenylphosphane)molybdenum(II)

The title compounds, [Mo(C5H5)(COCH3)P(CH3)2(C6H5)(CO)2], (1), and [Mo(C5H5)(COCH3)P(C2H5)(C6H5)2)(CO)2], (2), have been prepared by phosphine-induced migratory insertion from [Mo(C5H5)(CO)3(CH3)]. Both complex molecules exhibit a four-legged piano-stool geometry with trans-disposed carbonyl ligands along with Mo—P bond lengths and C—Mo—P angles that reflect the relative steric pressure of the respective phosphine ligand. The structure of compound (1) exhibits a layered arrangement parallel to (100). Within the layers molecules are linked into chains along [001] by non-classical C—H...O interactions between the acetyl ligand of one molecule and the phenyl and methyl phosphine substituents of another. In the structure of complex (2), a chain motif of centrosymmetrical dimers is found along [010] through C—H...O interactions