Highly Stereoselective Photochemical Oxidative Addition Reactions. Preliminary Communication

Cyclometallated complexes of the type cis ‐bis(2‐phenylpyridine)platinum(II) (C 22 H 16 N 2 Pt) and cis ‐bis(2‐(2′‐thienyl)pyridine)platinum(II) (C 18 H 12 N 2 S 2 Pt) undergo thermal or photochemical oxidative addition (TOA or POA) reactions with a number of substrates. TOA (with CH 3 I, CH 3 CH 2 I etc. ) yield mixtures of several isomers which rearrange slowly (within ca. one week at room temperature) to one of the possible cis ‐isomers. CH 2 Cl 2 , CHCl 3 , or ( E )ClCHCHCl, 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 1 H‐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 .