Exchange at Square-Planar Platinum II

The hydrolysis of [PtCl4] in basic solution has been followed using NMR spectroscopy.Four sequential reactions were observed in the reaction of 0.05 M substrate with 1.0 M NaOH, Eq. (1). The individual steps 

The displacements of dimethylsulfoxide from [PtX(dmso)(biL)] [X = C1 or Br biL = bipyridine (bipy) or 1,10-phenanthroline (phen)] by Cl are quite rapid, and follow the curious rate law (5). The chloride-independent part, ki, was too small to be detected directly. The second-order 

Complex (2) is fluxional, by NMR techniques. The molecular motion arises from internal nucleophilic attack at Pt by the pendant arm of the potentially tridentate ligand, and /pt p is retained at the high temperature limit, confirming the intramolecular nature of the process.  

The antitumor activities of some sulfoxide complexes themselves, [PtCl(RR S0)(biL)]N03 (biL are diamines), have come under scrutiny, being the first active compounds of this sort with sulfur-bonded ligands. The nature (and, when appropriate, the chirality) of the sulfoxides has a marked effect on activity. The sulfoxides can be displaced by Cl or H2O, and the lability order is Ph2SO PhMeSO (tol)MeSO (PhCH2)2SO (PhCH2)MeSO dmso. Initial loss of RR SO was precluded as the mechanism of the antitumor activity. Possibly RR SO is eliminated after the platinum has bound to DNA. 

The kinetics of formation of cw-[Pt(OH2)2(NH3)2] under basic conditions and its anation to [PtCl2(NH3)2] have been measured. Under physiological conditions, cw-[Pt(OH2)2(NH3)] is considered to be the least important of all the potential hydrolysis products of Cisplatin, Pt NMR spectroscopy has been used to follow the kinetics of the binding of both Cisplatin and its trans isomer to The two isomers react by pseudo- 

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Associative Ligand Exchange at Square-Planar Platinum(II)... 

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