Cyclometalated C^C* Platinum(IV) NHC Complexes

We present a previously unknown
series of cyclometalated platinum(IV)
NHC complexes, obtained by oxidative addition of iodine, iodomethane,
and different benzyl bromides to platinum(II) complexes with cyclometalated
C^C* dibenzofuran, dibenzothiophene, and phenylimidazole ligands together
with an acetylacetonate ligand. All compounds were characterized by
standard techniques (1H, 13C, and 195Pt NMR and elemental analysis), and for three complexes, solid-state
structures could be obtained. DFT calculations (B3LYP(d3)/def2-TZVPP
including dispersion interactions in dichloromethane and acetone)
were performed to investigate the mechanism of the oxidation and explain
the exclusive formation of the observed trans products.