LIGAND ISOMERISM AND STACKING IN SQUARE-PLANAR PLATINUM(II) COMPLEXES .2. EVIDENCE FOR MIXED-ISOMERISM IN PT[DMBP(CSN)2]

Three linkage isomers of Pt[dmbp(CSN)2], where dmbp = 4,4'-dimethylbipyridine, have been prepared and examined by FT-IR, C-13 solution and N-15 MAS NMR, and Pt-L3 EXAFS spectroscopies, in order to elucidate the bonding properties of these square planar complexes. The spectral data show that these complexes can exist as the kinetically favored -(SCN)2 form I, the-(SCN)(NCS) form II, obtained by heating I as the neat solid, and the thermodynamically favored -(NCS)2 form III, obtained by recrystallization of I from aprotic solvents. Evidence for a Pt-Pt interaction in solid III is inferred from the Pt-L3 EXAFS results.