THE CONFORMATIONAL-ANALYSIS OF PHOSPHINE-LIGANDS IN ORGANOMETALLIC COMPLEXES - PART 1 - TRIPHENYLPHOSPHINE COORDINATED TO AN ACHIRAL METAL CENTER

The conformational analyses of PPh3 1 and the representative achiral m etal complexes [Al(PPh3)(Me)(3)] 2, [Fe(PPh3)(CO)(4)] 7 and [Ir(PPh3)( 2)(CO)(3)](+) 8 possessing tetrahedral and trigonal-bipyramidal geomet ries are reported, and comparisons between the calculated and solid-st ate structures are made. The intramolecular non-bonded interactions wh ich govern the conformational preferences of PPh3 in both the free and complex-bound state are characterised, The equilibrium between the op posing inter ring-ring and inter ring-ligand interactions which govern the minimum energy conformations of these complexes is examined, Anal ysis of the conformational preferences of PPh3 ligands in metal comple xes is facilitated by the introduction of the novel concept of the pla ne of nadir energy.