CYCLOMETALATED DERIVATIVES OF PLATINUM(II) DERIVED FROM 1,4-BENZODIAZEPIN-2-ONES - CRYSTAL AND MOLECULAR-STRUCTURE OF PT(L)(HL)CL YDRO-1-METHYL-5-PHENYL-2H-1,4-BENZODIAZEPIN-2-ONE, DIAZEPAM), A MOLECULE CONTAINING A NEUTRAL AND A DEPROTONATED 1,4-BENZODIAZEPIN-2-ONE

The complexes [Pt(L)Cl](2) (1), Pt(L)(HL)Cl (2), (two conformers, 2a a nd 2b), Pt(L)(Ph(3)P)Cl (3), Pt(L)(S,5-Me(2)-py)Cl (4) and Pt(L)(CO)CI (5) (HL = ydro-1-methyl-5-phenyl-2H-1,4-benzodiazepin-2-one, DIAZEPAM ) have been prepared and characterized by IR, MS and H-1, C-13, P-31, and two-dimensional correlation NMR spectra. Complexes 1-5 contain a d eprotonated DIAZEPAM coordinated to the metal through the N(4) atom an d the ortho-carbon of the 5-phenyl substituent. In complex 2, as shown by a single crystal X-ray structure determination, carried out on con former 2a, in addition to the cyclometallated system, a neutral molecu le of DIAZEPAM is coordinated through the N(4) atom. The crystals of c ompound 2a, C32H25Cl3N4O2Pt, are monoclinic, space group P2(1)/n with a = 13.601(3), b = 15.951(5), c = 13.837(3) Angstrom, beta = 96.38(2)d egrees, Z = 4. The structure was refined to R = 0.021 and R(w) = 0.032 on the basis of 4922 unique reflections with I>3 sigma(I). The platin um atom is in a square planar geometry with the carbon atom trans to t he chloride ligand: Pt-C = 1.983(3), Pt-Cl = 2.402(1), Pt-N = 2.031(3) and 2.009(3) Angstrom.