Synthesis and crystal structure of the first complex containing a chelating selenourea dianion ligand

Reaction of N,N'-diphenylselenourea, PhNHC(Se)NHPh, with cis-[PtCl2(PPh3)(2)] and triethylamine in hot methanol gives the first example of a selenourea dianion complex, [Pt{SeC(=NPh)NPh}(PPh3)(2)] isolated as a yellow solid in high yield. The structure of the complex was determined by X-ray crystallography and found to be similar to the related thiourea dianion complex [Pt{SC(= NPh)NPh}(PPh3)(2)], with a Pt-Se-C-N four-membered ring. The antitumour activity (P388 murine leukaemia cells) of the selenourea dianion complex was determined, together with a small selection of related platinum(II) -thiourea dianion complexes (prepared by an analogous method) for comparison. The complex [Pt{SC(=NMe)NMe}(PPh3)(2)] showed high activity [IC(50)1.0 muM], with the other complexes showing moderate to low activity. (C) 2003 Elsevier B.V. All rights reserved.