A comparison of C3R3P3 and C6R3H3 as ligands using photoelectron spectroscopy and density functional theory

Photoelectron spectra have been recorded for [M(CO)(3)(eta(6)-(C3Bu3P3)-P-t )] (M = Cr, Mo or W) and [Mo(CO)(3)(eta(6)-(C3Bu3H3)-H-t)]. They are assign ed by comparison with analogous spectra and density functional calculations . The phospha-arene complexes show a higher first IE than carbocyclic analo gues. Electronic structure analysis indicates stronger bonding in the forme r as a result of greater metal-ligand back donation to the lower lying LUMO s of the P substituted ring.