Nitrosyl complexes of rhenium

Abstract

The complex [ReCl₂(N₂COPh)(PPh₃)₂](I) reacts with nitrogen oxide to give the five-co-ordinate paramagnetic complex [ReCl₂(NO)(PPh₃)₂](II) which adds other ligands, L, to form six-co-ordinate diamagnetic complexes [ReCl₂(NO)(PPh₃)₂L](III). Generally tertiary phosphines (PR₃) displace triphenylphosphine from (II) to give either [ReCl₂(NO)(PR₃)₂] or [ReCl₂(NO)(PR₃)₃], analogous to (II) and (III) respectively, depending on the bulk of the phosphine PR₃, but dimethylphenylphosphine tends to give [ReCl₂(NO)(PMe₂Ph)₂(PPh₃)]. The nitrogen oxide in the above complexes is inert to attack by either electrophilic or nucleophilic reagents.