The new redox systems (acac)2Ru(m-Q1)Ru(acac)2n (1n) and (acac)2Ru(m-Q2)Ru(acac)2n (2n) with Q1 = 1,10-phenanthroline-5,6-dione and Q2 = 1,10-phenanthroline-5,6-diimine were studied for n = +, 0, -, and 2- using UV-visible-NIR spectroelectrochem. and, in part, EPR and susceptometry. The ligands can bind the first metal (left) through the phenanthroline N atoms and the second metal (right) at the o-quinonoid chelate site. The neutral compds. are already different: Compd. 1 is formulated as a RuII(m-Q1).bul.-RuIII species with partially coupled semiquinone and Ru(III) centers. In contrast, a RuIII(m-Q2)2-RuIII structure is assigned to 2, which shows a weak antiferromagnetic spin-spin interaction (J = -1.14 cm-1) and displays an intense half-field signal in the EPR spectrum. The 1-electron reduced forms are also differently formulated as RuII(m-Q1)2-RuIII for 1- with a RuIII-typical EPR response and as RuII(m-Q2).bul.-RuII for 2- with a radical-type EPR signal at g = 2.0020. In contrast, both 12- and 22- can only be described as RuII(m-Q)2-RuII species. The monooxidized forms 1+ and 2+ show very similar spectroscopy, including a RuIII-type EPR signal. Although no unambiguous assignment was possible here for the alternatives RuII(m-Q)0RuIII, RuIII(m-Q)2-RuIV or RuIII(m-Q).bul.-RuIII, the last description is favored. The reasons for identical or different oxidn. state combinations are discussed. on SciFinder(R)
Please log in
to take part in the discussion (add own reviews or comments).