Dinuclear C,N,C cyclometalated platinum derivatives with bridging delocalized ligands.: Fourfold deprotonation of 6,6′-diphenyl-2,2′-bipyridine, H4L, promoted by Pt(R)2 fragments (R = Me, Ph).: Crystal structures of [Pt2(L)(3,5-Me2py)2] and {Pt2(L)(dppe)}2 (dppe=1,2-bis(diphenylphosphino)ethane).: X-ray powder diffraction of [Pt2(L)(CO)2]

cis-[Pt(R)(2)(DMSO)(2)] (R = Me, Ph) reacts with 6,6'-diphenyl-2,2'-bipyridine (H4C) in a 2:1 molar ratio, giving the unusual, very slightly soluble dinuclear complex [Pt-2(L)(DMSO)(2)] (1). The reaction implies activation of four C-H bonds: in 1 a fourfold deprotonated H4L links two Pt-DMSO fragments acting as a delocalized C,N,C boolean AND C,N,C 12-electron donor. From I more soluble dinuclear [Pt-2(L)(L')(2)] (L' = bulky 2-electron donors such as PR3 and substituted pyridines) species, 2-6, and polynuclear {Pt-2(L)(L-L)}(n) (L-L = Ph2P(CH2)(x)PPh2 (x = 1, dppm; x = 2, dppe; x = 3, dppp)) species, 7-9, have been obtained by substitution of the DMSO ligands. DMSO can also be displaced from I by CO, both in solution and in the solid state, to give the flat and completely insoluble complex [Pt-2(L)(CO)(2)] (10). The structures of [Pt-2(L)(3,5-Me-2-Py)(2)] (5) and {Pt-2(L)(dppe)}(2) (8) have been determined by single-crystal X-ray diffraction analysis, while a powder X-ray diffraction analysis has been performed on complex 10, [Pt-2(L)(CO)(2)]. With a 1:1 Pt:L molar ratio a mononuclear complex, [Pt(H2L)(DMSO)] (11), is obtained, where the twofold deprotonated ligand is C,N,C coordinated. Also, the DMSO can be displaced from 11 by neutral ligands, L', such as CO, PPh3, and 3,5-Me-2-PY to give [Pt(H2L)(L')] (12-14). Compounds 11-14 further react with cis-[Pt(R)(2)(DMSO)(2)] to give dinuclear complexes. This two-step approach allows us to obtain species with different ligands around each platinum atom, [Pt-2(L)(L')(L)] (15-18).