Donor Properties of Diphosphine Ligands in Tungsten Carbonyl Complexes:  Synchrotron Radiation XPS Measurements and DFT Calculations

Synchrotron radiation XPS measurements of W 4f and P 2p core level binding energies in the series W(CO) 4 (P−P) (P−P = dppm ( 1 ), dppe ( 2 ), dppp ( 3 ), dppb ( 4 ), dmpe ( 5 ), F-dppe ( 6 ); dppm = bis(diphenylphosphino)methane, dppe = 1,2-bis(diphenylphosphino)ethane, dppp = 1,3-bis(diphenylphosphino)propane, dppb = 1,4-bis(diphenylphosphino)butane, dmpe = 1,2-bis(dimethylphosphino)ethane, F-dppe = 1,2-bis(bis(pentafluorophenyl)phosphino)ethane) are reported. The results are interpreted in terms of effects of the chelate ring size and of the nature of substituents of the P atoms. The trend of XPS data show an excellent agreement with the results of DFT calculations, obtained by the ΔSCF approach. Further analysis of the Kohn−Sham eigenvalues calculated at the ground-state level has assessed the role played by the initial state effects.