Inorganic Chemistry, Vol.50, No.15, 7074-7079, 2011
Electronic Coupling between Two Cyclometalated Ruthenium Centers Bridged by 1,3,6,8-Tetrakis(1-butyl-1H-1,2,3-triazol-4-yl)pyrene
A new bridging ligand 1,3,6,8-tetralcis(1-butyl-1H-1,2,3-triazol-4-yl)pyrene (ttapyr) was designed and synthesized by "dick" chemistry. This ligand was used to construct a linear dimetallic biscyclometalated Ru(II) complex [(tpy)Ru(ttapyr)Ru(tpy)](2+) and a monometallic complex [(tpy)Ru(ttapyr)](+), where tpy is 2,2':6',2"-terpyridine. The electronic properties of these complexes were studied and compared by electrochemical and spectroscopic methods with the aid of DFT calculations. One-electron oxidation of [(tpy)Ru(ttapyr)Ru(tpy)](3+) with cerium ammonium nitrate produced a mixed-valent complex [(tpy)Ru(ttapyr)Ru(tpy)](3+). The intramolecular electronic coupling between individual metal centers was quantified by the intervalence charge transfer transition analysis. Mixed-valent complex [(tpy)Ru(ttapyr)Ru(tpy)](3+) exhibits a metal-centered rhombic EPR signal at 77 K with an average g factor of 2.203.