SYNTHESIS AND REACTION CHEMISTRY OF MONOMERIC AND DIMERIC AMIDE COMPLEXES OF PLATINUM(II)

A series of complexes trans-[PtH(NH3)L2]ClO4 (L = PPh3, PEt3, PCy3), trans-[PtMe(NH3)L2]ClO4 (L = PPh3, PEt3, PMePh2, PCy3), and [PtMe(NH3)dppe]ClO4 have been synthesized from trans-PtH(ClO4)L2, trans-PtMe(ClO4)L2, and PtMe(ClO4)dppe and ammonia, respectively. Reacting trans-[PtH(NH3)L2]ClO4 (L = PPh3, PEt3) with NaNH2 gives [PtH(mu-NH2)L]2 as a mixture of anti and syn isomers. The complexes reductively eliminate ammonia. Reacting trans-[PtMe(NH3)L2]ClO4 (L = PPH3, PEt3, PMePh2) with NaNH2 gives the stable complexes [PtMe(mu-NH2)L]2 as mixtures of anti and syn isomers. For L = PPh3, PMePh2, PEt3, the percentage anti isomer is 100, 75, and 50, respectively. For L = PEt3, the intermediate complex trans-PtMe(NH2)(PEt3)2 has been observed. Reacting [PtMe(mu-NH2)L]2 with L (L = PPh3, PEt3) gives cis-PtMe(NH2)L2. Reacting trans-[PtH(NH3)(PCy3)2]ClO4, trans-[PtMe(NH3)(PCy3)2]ClO4, or trans-[PtPh(NH3)(PCy3)2]ClO4 with NaNH2 gives trans-PtH(NH2)(PCy3)2, trans-PtMe(NH2)(PCy3)2, or trans-PtPh(NH2)(PCy3)2. Reacting [PtMe(mu-Cl)PCy3]2 with AgClO4 then NH3 gives [PtMe(NH3)2PCy3]ClO4. Treating [PtMe(NH3)2PCy3] with NaNH2 gives an equimolar mixutre of anti and syn isomers of [PtMe(mu-NH2)PCy3]2. The syn isomer, which has been isolated, converts to a mixture of syn and anti in the presence of tricyclohexylphosphine in CDCl3 solution. The compound anti-[PtMe(mu-NH2)PPh3]2 crystallizes in the space group C2/c with a = 22.592 (5) angstrom, b = 11.844 (3) angstrom, c = 29.403 (6) angstrom, beta = 116.43 (2) degrees, and Z = 8. The two crystallographically independent molecules with Pt(1)-Pt(1A) and Pt(2)-Pt(2A) distances of 3.106 (1) and 3.117 (1) angstrom, respectively, are associated by Pt...H interactions. The complex trans-PtMe(NH2)(PCy3)2 reacts with CF3SO3H to give trans-[PtMe(NH3)(PCy3)2]CF3SO3. The complex trans-PtPh(NH2)(PCy3)2 reacts with CF3SO3H and H2O to give trans-[PtPh(NH3)(PCy3)2]CF3SO3 and trans-PtPh(NH2)(PCy3)2 reacts with methyl iodide and allyl chloride to give trans-PtPhI(PCy3)2 and trans-PtPhCl(PCy3)2, respectively. Carbon dioxide reacts with trans-PtPh(NH2)(PCy3)2 to give trans-PtPh(NHCO2H)(PCy3)2 then trans-PtPh(OCONH2)(PCy3)2.