A study of the molecular and electronic structures of the indium(I) phospholyls [In(eta(5)-P2C3Bu3t)] and [In(eta(5)-P3C2Bu2t)] by X-ray diffraction,photoelectron spectroscopy and density functional theory dagger

The crystal and molecular structures of [In(eta(5)-P2C3Bu3t)] are reported. He I and He II photoelectron (PE) spectra of [In(eta(5)-P3C2Bu2t)] and of [In(eta(5)-P2C3Bu3t)] are assigned by comparison with related systems and w ith the aid of density functional calculations of the ionisation energies ( IE). In both cases the first PE band comprises ionisation from the ring pi levels together with an ionisation from a P sigma orbital. The second band is due to ionisation from an In-ring antibonding orbital with In s characte r. Other P sigma ionisation bands lie at higher IE. Substitution of CBut by P within the five membered aromatic ring increases the IE of related bands . Geometry optimisation of the parent complexes [In(eta(5)-P3C2H2)] and [In (eta(5)-P2C3H3)] gave structural parameters in good agreement with the X-ra y data. Attempts to find an energy minimum corresponding to eta(1)-coordina tion were unsuccessful, the structures reverting to the eta(5)-coordination mode. Bonding of the ring is principally due to overlap of the two upper o ccupied pi orbitals with the In 5p orbitals. Some rehybridisation at the P atoms assists this overlap. Mulliken population analysis shows the In 5p oc cupation to be ca. half an electron in both cases.