Highly Stereoselective Photochemical Oxidative Addition Reactions. Preliminary Communication

Cyclometallated complexes of the type cis-bis(2-phenylpyridine)platinum(II) (C₂₂H₁₆N₂Pt) and cis-bis(2-(2′-thienyl)pyridine)platinum(II) (C₁₈H₁₂N₂S₂Pt) undergo thermal or photochemical oxidative addition (TOA or POA) reactions with a number of substrates. TOA (with CH₃I, CH₃CH₂I etc.) yield mixtures of several isomers which rearrange slowly (within ca. one week at room temperature) to one of the possible cis-isomers. CH₂Cl₂, CHCl₃, or (E)? ClCH?CHCl, e.g., do not react thermally. POA yield directly complexes of Pt(IV) with the halide and a σ-bonded C-atom in cis-position. The configuration, as assigned by extensive use of ¹H-NMR data, can be characterized for the two chelating ligands C …? N and C′ …? N′ by C,C′-cis; N,N′-cis and C(chelate), Cl-trans.