SYNTHESIS, PROPERTIES AND CRYSTAL-STRUCTURES OF [RU(III) (TACN)2(MU-OH)2(MU-CO3)]BR2-CENTER-DOT-3.75H2O AND [RU(3.5)22(DTNE)(MU-O)2(MU-CO3)]PF6-CENTER-DOT-5H2O [TACN = 1,4,7-TRIAZACYCLONONANE, DTNE = 1,2-BIS(1,4,7-TRIAZACYCLONONAN-1-YL)ETHANE]

The mono- and di-nuclear complexes [Ru(III)(tacn)Cl3] 1, [Ru(III)2(dtne)Cl6] 2, and [Ru(III)2(dtne)Br6] 3 have been synthesised from [Ru(II)(dmso)4Cl2] (dmso = dimethyl sulfoxide), the respective amine and concentrated HCl or H Br in the presence of air where tacn and dtne represent 1,4,7-triazacyclononane and 1,2-bis(1,4,7-triazacyclononan-1-yl)ethane. The compounds proved to be useful starting materials for the hydrolytic generation of hydroxo/oxo-bridged dinuclear Ru(III)2 and Ru(III)Ru(IV) species in aqueous solution containing sodium carboxylates or sodium carbonate. The diamagnetic red-purple species Ru(III)2(dtne)-(mu-OH)2(mu-PhCO2)][PF6]3 4 and its green mu-carbonato analogue [Ru2(III)(tacn)2(mu-OH)2(mu-CO3)]Br2. 3.75H2O 5 were prepared. Replacement of the mu-carboxylato bridge in 4 by a mu-CO32- bridge in the presence of air gave green crystals of the mixed-valent species [Ru3.5(2)(dtne)(mu-O)2(mu-CO3)] PF65H.O 6. Complexes 5 and 6 have been structurally characterized by X-ray crystallography; both contain a bioctahedral edge-sharing unit of Ru(III)2(mu-OH)2(mu-CO3)2+ and Ru3.5(mu-O)2(mu-CO3)+, respectively, with Ru-Ru metal-metal bonds [2.560(1) in 5, 2.469(1) in 6]. The Ru(IV)2 analogues of 5 and 6 have been generated chemically and electrochemically in solution. The UV/VIS spectra, magnetic properties and the electrochemistry of 4-6 are reported.