Thiocyanatocarbonyl complexes of manganese(I)

Article abstract of DOI:10.1021/ic50032a007

A series of thiocyanatocarbonyl complexes of manganese(I) was prepared by reaction of thiocyanatopentacarbonylmanganese(I) with neutral ligands L, where L is an amine, phosphine, arsine, or stibine, and/or by metathesis involving analogous chloro or bromo complexes and potassium thiocyanate. The infrared spectra suggest that the tetracarbonyls, Mn(CO)₄L(SCN), are sulfur-bonded in the solid phase and chloroform solutions, whereas the trans and cis tricarbonyls, Mn(CO)₃L₂(CNS), are nitrogen-bonded, the apparent exceptions being cis-Mn(CO)₃[As(C₆H₅)₃] ₂SCN and cis-Mn(CO)₃[Sb(C₆H₅)₃] ₂SCN. A possible explanation of these modes of manganese-thiocyanate attachment is offered in terms of Mn=C=O π bonding. Some unusual spectral features of the nitrogen-bonded cis tricarbonyls are also presented and interpreted on the basis of the proposed bonding hypothesis. It is suggested that steric factors play a major role in stabilizing manganese-sulfur linkage in the cis tricarbonyls containing triphenylarsine and -stibine. Finally, metal-thiocyanate bonding in six-coordinate manganese(I) carboriyls is compared with that in four-coordinate palladium(II) complexes.