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 [Pt-2(L)(3,5-Me(2)py)(2)] and {Pt-2(L)(dppe)}(2) (dppe=1,2-bis(diphenylphosphino)ethane). X-ray powder diffraction of [Pt-2(L)(CO)(2)]