Synthesis of Novel Pseudocloso Ruthenacarboranes based on an Unsubstituted nido‐C2B9H112− Ligand

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. First examples of pseusocloso‐metallacarboranes based on unsubstituted C2B9H112− ligand and tridentate aminopyridines were obtained. The relationships between complex structure, ligand environment, spectral characteristics, electrochemical properties and cage conformation were analyzed. The factors determining pseudocloso or closo conformation of metallacarborane cluster were discussed.