Bridging ability of [bis{2,3-di(2 '-pyridyl)pyrazine}platinum(II)] and [bis(2,2 '-bipyrimidine)platinum(II)] moieties in polymetallic architecture

Factors influencing formation of [{Ru(2,2'-bipyridine)(2)(BL)}(2)Pt](6+) co mplexes, where BL are 2,2'-bipyrimidine (bpm) and 2,3-bis-(2'-pyridyl)pyraz ine (dpp), were discussed in terms of pi-accepting/sigma-donating propertie s of BL and strain energies of the complexes, sigma-Donation from BL to Pt( II) is crucial in formation of the Pt(BL)(2) type bridging moiety; pyridine provides a stronger coordination bond than pyrazine or pyrimidine, while K -back donation seems less favored. Shifts in redox potentials suggest intra molecular Ru(II) to Pt(II) charge flow through BL. Adaptable conformation i s also essential in the BL structure to reduce strain upon bridging two coo rdination cores. High bridging ability of dpp in the polymetallic synthesis is indicated.