The complex [PtMe2(dppa)], 1a, dppa = Ph2PNHPPh2, which has previously been prepared as a mixture with the dimeric form [Pt2Me4(-dppa)2], was synthesized in pure form by the reaction of [PtCl2(dppa)] with MeLi. The aryl analogue [Pt(p-MeC6H4)2(dppa)], 1b, was prepared by replacement of SMe2in cis-[Pt(p-MeC6H4)2(SMe2)2] with dppa. The reaction of the chelate complexes 1 with one equiv. of dppa afforded the complexes [PtR2(dppa-P)2], RMe, 2a and R = p-MeC6H42b. The reaction of [PtR2(dppa)], 1, with neat MeI gave the organoplatinum(iv) complexes [PtR2MeI(dppa)], RMe, 5a and R = p-MeC6H4, 5b. The structure of 5a, determined by X-ray crystallography, indicated that the complex undergoes self-assembly by intermolecular N-H⋯I-Pt hydrogen bonding. MeI was also double oxidatively added to organodiplatinum(ii) complex cis,cis-[Me2Pt(-SMe2)(-dppa)PtMe2], to give diorganoplatinum(iv) complex [Me3Pt(-dppa)(-I)2PtMe3], 4. The aryl analogue organodiplatinum(ii) complex cis,cis-[(p-MeC6H4)2Pt(-SMe2)(-dppa)Pt(p-MeC6H4)2], 3b, was prepared by the reaction of cis-[Pt(p-MeC6H4)2(SMe2)2] with half equiv. of dppa, but 3b refused to react with MeI, probably because of the steric effects of the aryl ligands. The tetramethyl complex [PtMe4(dppa)], 6, was prepared either by reaction of 5a with MeLi or by replacement of SMe2in [Pt2Me8(-SMe2)2] with dppa. All the complexes were fully characterized in solution by multinuclear NMR (1H,13C,31P and195Pt) methods and their coordination compared with that of the corresponding known dppm complexes. © The Royal Society of Chemistry.
