The role of R3P–M bond bending in determining the stereochemical features of tertiary phosphine complexes of transition metals

Abstract

For cis- and trans-MXY(PR₃)₂‘planar’ systems (M = Ni, Pd, Pt) the large deviations of ∠PMP bond angles from ideal {defined as α=(∠PMP –90°)cis; (180°–∠PMP)trans} are shown to correlate linearly with the average R₃P tilt angle β_avg. [β=(180°–∠C_TPM) where C_T= the centroid of the (α-C)₃ unit of a R₃P ligand]: the data are best rationalised by assuming that unfavourable electron repulsions involving C(α-C)₃ units and neighbouring ligands are minimized by R₃P–M bond bending.