A Platinum−Ruthenium Dinuclear Complex Bridged by Bis(terpyridyl)xanthene

4,5-Bis(terpyridyl)-2,7-di-tert-butyl-9,9-dimethylxanthene (btpyxa) was prepared to serve as a new bridging ligand
via Suzuki coupling of terpyridin-4‘-yl triflate and 2,7-di-tert-butyl-9,9-dimethylxanthene-4,5-diboronic acid. The reaction
of btpyxa with either 1 equiv or an excess of PtCl2(cod) (cod = 1,5-cyclooctadiene) followed by anion exchange
afforded mono- and dinuclear platinum complexes [(PtCl)(btpyxa)](PF6) ([1](PF6)) and [(PtCl)2(btpyxa)](PF6)2 ([2](PF6)2), respectively. The X-ray crystallography of [1](PF6)·CHCl3 revealed that the two terpyridine units in the
ligand are nearly parallel to each other. The heterodinuclear complex [(PtCl){Ru(tBu2SQ)(dmso)}(btpyxa)](PF6)2
([4](PF6)2) (dmso = dimethyl sulfoxide; tBu2SQ = 3,5-di-tert-butyl-1,2-benzosemiquinone) and the monoruthenium
complex [Ru(tBu2SQ)(dmso)(trpy)](PF6) ([5](PF6)) (trpy = 2,2‘:6‘,2‘ ‘-terpyridine) were also synthesized. The CV of
[2]2+ suggests possible electronic interaction between the two Pt(trpy) groups, whereas such an electronic interaction
was not suggested by the CV of [4]2+ between Pt(trpy) and Ru(tBu2SQ) frameworks.