NUCLEOPHILIC DISPLACEMENT OF HALIDES FROM MONOCATIONIC PLATINUM(II) COMPLEXES CONTAINING NEUTRAL TRIDENTATE CHELATING LIGANDS WITH SULFUR AND NITROGEN DONORS - KINETICS AND EQUILIBRIA

Kinetic and equilibrium measurements on the displacement of halides fr om the substrates [Pt(L)X](+) [L = diethylenetriamine. 2,6-bis(methyls ulfanylmethyl) pyridine, bis(2-pyridylmethyl) sulfide or 2,2':6',2 ''- terpyridine, X = Cl, Br or I] with the nucleophiles Cl-, Br- and I- ha ve been carried out in methanol at 25 degrees C and constant ionic str ength. The results are discussed in terms of the relative stability of the planar ground and five-co-ordinate transition states. The signifi cant differences in kinetic behaviour along the series are related to the presence of pi-interacting pyridine rings as well as to the nature of the donor atoms trans and cis to the replaceable halogen. The equi librium parameters. the leaving-group effect and the intimate mechanis m are also discussed and compared with literature data.