HETERONUCLEAR MU-1-METHYLCYTOSINATO-N3,N4 COMPLEXES CONTAINING VERY SHORT PT-]CU DATIVE BONDS

A series of mixed Pt-II,Cu-II complexes derived from trans-[a(2)Pt(1-M eC-N3)(2)](2+) (a = NH3 or CH3NH2; 1-MeC = 1-methylcytosine, coordinat ed to Pt via N3) and of general formula trans-[a(2)Pt(1-MeC(-)-N3,N4)( 2)CuL](n+) with L = mu-CO32- (1, 2), OH- (3), NH3,H2O (4), 1-MeC-N3 (5 ), 9-EtGH-N7,H2O (6) have been isolated and characterized by X-ray ana lysis. In all compounds a trans-a(2)Pt(II) entity is bound to two cyto sine nucleobases via N3 sites each, whereas a Cu-II is bound to two mo nodeprotonated N4 sites. In all cases Pt-II represents a ligand of Cu- II, which either displays a distorted square-planar (1, 2, 3, 5) or a pentacoordinate environment (4, 6). Pt-II-Cu-II distances are very sho rt, ranging from 2.49 to 2.56 Angstrom in the six compounds. EPR spect ra of frozen solutions have been examined in several cases. They appea r, at least for 4a and 5, to be consistent with Pt-Cu hyperfine intera ctions rather than the presence of two different Cu-only species.