Platinum(II) phosphine complexes of dicarboxylates and ammonia: Crystal structures of [{Pt(PPh3)(2)}(2){mu-1,3-(O2C)(2)C6H4}(2)], [{Pt(PPh3)(2)-(NH3)}(2){mu-1,4-(O2C)(2)C6H4}][PF6](2) and cis-[Pt(PPh3)(2)(NH3)(2)][NO3](2)

The reaction of [Pt(PPh3)(2)(CO3)] with a rigid dicarboxylic acid H2L gave rise to dimeric compounds [{Pt(PPh3)(2)}(2)(mu-L)(2)] 1 [H2L = C6H4(CO2H)(2)-1,4 (terephthalic acid) a, C6H4(CO2H)(2)-1,3 (isophthalic acid) b, trans, trans-HO2CCH=CHCH=CHCO2H (muconic acid) c or 4,4'-HO2CC6H4C6H4CO2H (biphenyldicarboxylic acid) d], which have been characterised spectroscopically and, in the case of Ib, crystallographically. When the reaction was carried out in the presence of NH4PF6 the NH4+ competed with the carboxylic acid and the major product from the reaction was [{Pt(PPh3)(2)(NH3)}(2)(mu-L)][PF6](2) 2, which has been characterised crystallographically for L= terephthalate. This suggests that NH4+ is acidic enough to react with [Pt(PPh3)(2)(CO3)], which has been confirmed by the synthesis of cis-[PtL2(NH3)(2)]X-2 [L = PPh3, X = PF6 3a or NO3 3b; L = PEt3, X = PF6 4a or NO3 4b; L-2 = Ph2PCH2CH2PPh2 (dppe), X = PF6 5a] from [PtL2(CO3)]. The complex cis-[Pt(PPh3)(2)((NH3)-N-15)(2)][NO3](2) was synthesized from (NH4NO3)-N-15 and characterised by a combination of P-31-{H-1}, N-15-{H-1}, Pt-195 and H-1 NMR spectroscopy. The crystal structure of cis-[Pt(PPh3)(2)(NH3)(2)][NO3](2) 3b has been determined and shows strong hydrogen bonding between the co-ordinated ammonia and the nitrate counter ions. The compound PhC2CO2H also reacted with [PtL2(CO3)], though the products were not the expected bifunctional carboxylates cis-[PtL2(O2CC2Ph)(2)] but the bis(phenylalkynyl) compounds cis-[PtL2(C2Ph)(2)] (L = PPh3 6, L-2 = dppe 7).