Complexes of Group VI hexacarbonyls with Group V ligands containing an olefinic side-chain

Abstract

The Group VI hexacarbonyls have been treated with potentially chelating ligands of the type CH₂CHCH₂CH₂EMe₂, where E = N, P, or As (nol, pol, and asol respectively). The amine forms solely chelate complexes with the general formula [M(CO)₄(nol)] with each hexacarbonyl; however, the phosphine and arsine form not only chelate complexes with this general formula but also complexes with the general formulae [M(CO)₄(CH₂:CHCH₂CH₂EMe₂)₂] and [M(CO)₅(CH₂:CHCH₂CH₂EMe₂)], in each of which the ligand is co-ordinated by way of the E atom only. The factors contributing to this behavioural difference between the ligands are discussed. For the complexes [M(CO)₄(nol)] and [W(CO)₄(pol)] variable-temperature i.r. studies are interpreted as indicating the presence of rotational isomers in solution. The mechanism whereby the isomers interconvert is discussed. The complexes [Mo(NO)₂Cl₂(asol)₂] and [PdCl₂(asol)] have been isolated from the reactions of asol with [Mo(NO)₂Cl₂] and [PdCl₂(NCPh)₂] respectively.