Organometallic platinum(ii) complexes of methyl-substituted phenanthrolines

Abstract

A series of dimesitylplatinum(II) complexes of symmetrically substituted dimethyl-1,10-phenanthrolines (dmphen) was prepared and examined in view of their electronic structure. Electrochemical data of the parent complexes and spectroscopic data of parent and one-electron reduced species reveal the variable electronic influence of the methyl substituents in different positions of the heteroaromatic system. From multi-frequency S, X, K and Q-band EPR measurements of the corresponding radical anions and of analogous species with 1,10-phenanthroline, 3,4,7,8-tetramethyl-1,10-phenanthroline and 2,2′-bipyridine ligands hyperfine coupling constants and g values were obtained and used for an estimation of the contributions from platinum orbitals to the singly occupied molecular orbital. X-Ray crystal structures are reported for [(2,9-dmphen)PtMes₂] and [(2,9-dmphen)PtPh₂], allowing us to probe the steric interactions between the methyl substituents of the phenanthroline and the mesityl ligands.