Factors influencing formation of [{Ru(2,2'-bipyridine)(2)(BL)}(2)Pt](6+) complexes, where BL are 2,2'-bipyrimidine (bpm) and 2,3-bis-(2'-pyridyl)pyrazine (dpp), were discussed in terms of pi-accepting/sigma-donating properties 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 intramolecular Ru(II) to Pt(II) charge flow through BL. Adaptable conformation is also essential in the BL structure to reduce strain upon bridging two coordination cores. High bridging ability of dpp in the polymetallic synthesis is indicated.