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Specific features of reactions of complex 5,6,10-{Cl(Ph3P)2Ru}-[5,6,10-(μ-H)3-10-H-exo-nido-7,8-C2B9H8] (1) with 1,2-bis(diphenylphosphino)benzene (dppbz) and bis(diphenylphosphino)methane (dppm) in acetonitrile in the presence of amines were studied. Novel closo-ruthenacarborane complexes containing the metal in a formal oxidation state of +2 were isolated. It was established that the reaction of 1 with dppbz affords a complex containing a coordinated acetonitrile molecule, whereas the reaction with dppm results in a tris(phosphine) complex with strongly sterically shielded ruthenium center. Reactions of the newly obtained compounds with carbon tetrachloride or hydrogen chloride give corresponding 17-electron complexes containing the metal atom in a formal oxidation state of +3. The reversibility of the RuII → RuIII redox transition in the compounds synthesized was investigated by cyclic voltammetry and the influence of the ligand environment on the values of the corresponding redox potentials was assessed. [ABSTRACT FROM AUTHOR]

The reaction of the known closo‐ruthenacarborane 3‐H‐3‐Cl‐3,3‐(PPh3)2‐closo‐3,1,2‐RuC2B9H11 with tridentade nitrogen‐based ligands of the general formula (C5NH4CH2)2NR (R=H, Me, Et, iPr, But) in benzene solution at 60 °C allowed us to isolate novel ruthenacarborane clusters 3,3,3‐(2'‐NC5H4CH2)2NR‐pseudocloso‐3,1,2‐RuC2B9H11. According to the performed X‐ray study, the obtained compounds are the first examples of pseudocloso‐metallacarboranes bearing unsubstituted C2B92−nido‐carborane ligand. In spite of the determined pseudocloso structure of the complexes in the solid state, the recorded 11B{1H} NMR spectra indicate that some of them are converted into the closo isomers in solution. The conducted quantum‐chemical calculations have confirmed the subtle difference between two configurations and possible rearrangement in solution. The performed electrochemical investigations show the ability of the formed ruthenacarboranes to undergo reversible oxidation to Ru(III) species. [ABSTRACT FROM AUTHOR]