CYCLOMETALATED DERIVATIVES OF PLATINUM(II) DERIVED FROM 6-(TERF-BUTYL)-2,2'-BIPYRIDINE (HL) - CRYSTAL AND MOLECULAR-STRUCTURE OF [PT(L)CL]

The reaction of K-2[PtCl4] with 6-(tert-butyl)-2,2'-bipyridine (HL) ga ve [Pt(L)Cl] 1a a cyclometallated species resulting from direct activa tion of a methyl C-H bond. The structure has been determined by X-ray diffraction. The crystals contain two independent molecules: average v alues for the principal parameters are Pt-Cl 2.300, Pt-C 2.003, Pt-N ( trans to C) 2.114 and Pt-N (trans to Cl) 1.948 Angstrom. The chlorine atom in 1a can easily be displaced by neutral ligands (L'); in the pre sence of NaBF4 the cationic species [Pt(L)(L')][BF4] (L' =PPh(3) 2, CO 3 or 3,5-dimethylpyridine 4) were isolated in good yields. With poten tially bidentate neutral ligands, L''-L'' [Ph(2)P(CH2)(2)PPh(2)(dppe), Ph(2)P(CH2)(2)AsPh(2) (dadpe) or Ph(2)PC=CPPh(2) (dppa)], [LPt(mu-L'' -L'')PtL](2+) (L''-L'' = dppe 5, dadpe 6 or dppa 7) or [PtL(L''-L'')]( +) species (L''-L'' = dppe 8 or dadpe 9) can be obtained by adequate c hoice of the L''-L'':Pt molar ratio (1:2 or 1:1, respectively). The ne w complexes 1-9 were characterized in solution by H-1, C-13-{H-1} and P-31-{H-1} NMR spectra.