Cyclometallated Derivatives of Platinum(II) derived from 6-(tert-Butyl)-2,2’-bipyridine (HL). Crystal and Molecular Structure of [Pt(L)Cl]

The reaction of K,[PtCI,] with 6-(tert-butyl)-2,2'-bipyridine (HL) gave [Pt(L)CI] l a a cyclometallated species resulting from direct activation of a methyl C-H bond. The structure has been determined by X-ray diffraction. The crystals contain two independent molecules: average values for the principal parameters are Pt-CI 2.300, Pt-C 2.003, Pt-N (trans to C) 2.1 14 and Pt-N (trans to Cl) 1.948 A. The chlorine atom in 1 a can easily be displaced by neutral ligands (L'); in the presence of NaBF, the cationic species [Pt(L)(L')] [BF,] (L' = PPh, 2, CO 3 or 3.5-dimethylpyridine 4) were isolated in good yields. With potentially bidentate neutral ligands, L"-L" [Ph,P(CH,),PPh, (dppe), Ph,P(CH,),AsPh, (dadpe) or Ph,PC=CPPh, (dppa)], [LPt(p-L"-L")PtL12+ (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 choice of the L"-L": Pt molar ratio (1 : 2 or 1 : 1, respectively). The new complexes 1-9 were characterized in solution by 'H, 13C-{lH} and ,lP-{'H} NMR spectra.