Tertiary phosphine complexes of triply bonded ditungsten bis(t-butylamide) tetrachloride. The X-Ray crystal structures of [W2Cl4(NHBut)2(PMe3)2], [W2Cl4(NHBut)2(PEt3)2] and cis-[W2Cl4(NHBut)2(PMe2Ph)2]

Abstract

The t-butylamine ligands in [W₂Cl₄(NHBu^t)₂(NH₂Bu^t)₂](1) have been replaced by trialkylphosphines giving the new complexes [W₂Cl₄,(NHBu^t)₂(PMe₃)₂](2), [W₂Cl₄(NHBu^t)₂(PEt₃)₂](3), and the isomeric [W₂Cl₂(NHBu^t)₂(PMe₂Ph)₂](4a) and (4b). X-Ray crystal structures showed that (2) and (3) have phosphines trans to the t-butylamides and short W–N bond lengths (1.76–1.81 Å). Compound (4) appears to form isomers one of which, (4a), was shown to have phosphines cis to the t-butylamides and a normal W–N bond length (1.92 Å).