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.