Parallel coordination of hydrazine to diruthenium units:: synthesis and molecular structure of the cationic complexes [(η6-C6Me6)2Ru2(μ2-H)2(μ2-η1,η1-H2NNH2)]2+ and [(η6-C6Me6)2Ru2(μ2-H)(μ2-η1,η1-H2NNH2)(μ2-NH2)]2+

The dinuclear cation [(eta(6)-C6Me6)(2)Ru-2(mu(2)-H)(3)](+) (1) reacts in aqueous solution with hydrazine to give the dicationic complexes [(eta(6)-C6Me6)(2)Ru-2(mu(2)-H)(2)(mu(2)-eta(1), eta(1)-H2NNH2)](2+) (2) and [(eta(6)-C6Me6)(2)Ru-2(mu(2)-H)(mu(2)-eta(1),eta(1)-H2NNH2)(mu(2)-NH2)](2+) (3). The single-crystal X-ray structure analyses of 2 (tosylate salt) and 3 (triflate salt) reveal both complexes to contain an intact hydrazine ligand coordinated parallel (mu(2)-eta(1),eta(1)) to the diruthenium backbone, comprising a Ru=Ru double bond (2.69 Angstrom) in 2 and a Ru-Ru single bond (2.85 Angstrom) in 3. A single crystal of the mixed sulfate-hexafluorophosphate salt of [(eta(6)-C6Me6)(2)Ru-2(mu(2)-H)(mu(2)-eta(1),eta(1)-H2NNH2)(mu(2)-N2H3)](2+) (4), isolated from the mother liquor of 2, suggests this hydrazido complex to be an intermediate in the reaction from 2 to 3. (C) 1998 Elsevier Science S.A. All rights reserved.