Heavier bis(m-terphenyl)element phosphaethynolates of group 13

The synthesis and reactivity of the heavier group 13 phosphaketene complexes (2,6-Mes₂C₆H₃)₂EPCO (1, E = Ga; 2, E = In) were reported. The reaction of 1 and 2 with 1,2,3,4-tetramethylimidazolin-2-ylidene, IMe₄, gave rise to the formation of (2,6-Mes₂C₆H₃)₂EP(O)C(IMe₄) (3, E = Ga; 4 E = In; Mes = mesityl). Subsequent addition of elemental tellurium proceeded via insertion into the E-P bond and provided (2,6-Mes₂C₆H₃)₂ETeP(O)C(IMe₄) (5, E = Ga; 6, E = In) comprising five-membered ETePCO-heterocycles. Compounds 1-6 were fully characterized by X-ray crystallography and heteronuclear NMR spectroscopy. The electronic structures of 1-6 were studied by DFT calculations and analyses of a complementary set of real-space bonding indicators (AIM, ELI-D, NCI) derived from the electron and pair densities, with focus on the bond characteristics of the PCO fragment.