Strong metal-metal coupling in mixed-valent intermediates Cl(L)Ru(m-tppz)Ru(L)Cl+, L = b-diketonato ligands, tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine. Dalton Transactions, (41)43:13429--13440, 2012. [PUMA: DFT;optimized MO MO;dinuclear acetylacetonate acetylacetonato crystal diketonate dinuclear electrochem mixed mol prepn pyridylpyrazine redox ruthenium structure valence]