SYNTHESIS AND CHARACTERIZATION OF NEW 2-BROMOVINYL SELENIDES AND THEIR PLATINUM-GROUP METAL-COMPLEXES

The synthesis of the 2-bromocyclooctenyl selenides, C8H12(Br)SeR (3a: R = Me; 3b: R = Et; 3c: R = CH2Ph), and the 2-bromocyclohexenyl selenides, C6H8(Br)SeR (4a: R = Me; 4b: R = Et; 4c: R = CH2Ph), is described. Compounds 3a-c and 4a, b react with K2PtCl4 to yield square planar platinum(II) complexes of the form trans-PtL2Cl2.(5a: L = 3a; 5b: L = 3b; 5c: L = 3c; 6a: L = 4a; 6b: L = 4b). The analogous palladium(II) complex trans-PdL2Cl2 (7c: L = 4c) has been prepared from Pd(C6H5CN)2Cl2. All new compounds have been characterised by NMR, infrared and mass spectroscopy and microanalysis. Complexes 5a-c, 6a, b and 7c exist as a racemic mixture of two diastereoisomers related by inversion at selenium. NMR spectroscopy shows that interconversion between these two isomers is slow for 5a-c, but faster for 6a, b and 7c.