Structural systematics - Part 7. Conformational behaviour of bridging diphenylphosphido ligands

Data retrieved from the Cambridge Structural Database for crystal structures containing (mu-diphenylphosphido) metal complexes, [M-2{mu-PPh2}] (where M is a d-block element), have been analysed to evaluate the conformational behaviour of these species. The observed distribution of torsion angles about the P-C bonds has been compared with the potential energy surface (PES) for phenyl rotations in a representative species [(AuBr)(2){mu-PPh2}](-) computed using the universal force field. Good agreement was obtained between the low-energy (<8 kJ mol(-1) above the global minimum) regions of the PES and the occupied regions of the two-dimensional P-Ph rotor conformation space. Phenyl ring rotations occur by coupled, geared disrotatory and uncoupled conrotatory motions of the phenyl groups in this and other classes of PPh2 rotors.