Multistep cyclometalation of solid trans-dichloro[3,3′-oxybis[((diphenylphosphino)methyl)-benzene]] platinum(II)

Article abstract of DOI:10.1021/om00077a001

A solid complex of a new trans-spanning bis(phosphine) ligand, trans-dichloro[3,3′-oxybis[((diphenylphosphino)methyl)benzene]] platinum(II), trans-PtCL₂(PoP), I, undergoes thermolysis at ca. 250°C with evolution of 2 mol of HC1 to form a doubly cyclometalated complex, [3,3′-oxybis[((diphenylphosphino)methyl)benzen]ato(2-)-C ₂,C₂′,P,P′]platinum(II), Pt(PoP-2H), II. Deuterium labeling in different positions (Chart I) shows that during thermolysis, approximately one ortho hydrogen of the phosphino phenyl groups is replaced by a HA proton (Chart I). This rearrangement is interpreted by a sequence of cyclometalation steps (Figure 5), one of which leads to an intermediate four-membered metallacycle. The reacting solid was investigated by thermogravimetry (TG), derivative thermogravimetry (DTG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC), partly with on-line mass spectral monitoring of the gaseous reaction product, by heating X-ray powder diffraction, and by optical microscopy. The results indicate that a short-lived fluid phase is involved when the reaction is carried out under optimal conditions.