Unprecedented single-pot synthesis of nitrile-derived ketoimino platinum(II) complexes by ring opening of Delta4-1,2,4-oxadiazolines

PtCl2(RCN)2] (1a R=CH2CO2Me, 1b R=CH2Cl) prepared upon EtCN replacement at PtCl2(EtCN)2] by the appropriate organonitrile, react with a cyclic nitrone -O-+N=CHCH2CH2C(Me)2, under mild conditions, to give, in an unprecedented single-pot synthesis involving spontaneous N-O bond cleavage, the ketoimino complexes trans-PtCl2RC(=O)N=CN(H)C(Me)2-CH2CH2]2 (2a, 2b) with two (pyrrolidin-2-ylidene)amino ligands. The analogous 2c (R=Et) and 2d (R=Ph) are formed by treatment with H2, in the absence of any added catalyst, of the Delta4-1,2,4-oxadiazoline complexes trans-PtCl2N=C(R)ONC(Me)2CH2CH2CH]2] (3a R=Et, 3b R=Ph) derived from the 2 + 3]-cycloaddition of the cyclic nitrone with the appropriate organonitrile complex of type 1. The compounds were characterized by elemental analyses, IR, 1H, (13C and 195Pt NMR spectroscopies, FAB mass spectrometry and X-ray structure analyses for 2a and 2d.