Synthesis, structure and properties of mixed-sandwich cobalta- and ferra-carboranes with ‘carbon-atoms-adjacent’ C2B9 and C2B10 systems

Several ‘carbon-atoms-adjacent’ mixed sandwich cobalta- and ferra-carboranes incorporating the C2B10 and C2B9 systems were synthesized via salt metathesis reactions followed by the oxidation with oxygen, which included unexpected cobaltacarboranes [(η5-C5H5){η6-[C6H4(CO)(CH2)]C2B10H10}]Co and [(η5-C5H5){η6-[C6H4(CHOH)(CH2)]C2B10H10}]Co. All new metallacarboranes were characterized by various spectroscopic techniques, elemental analyses and single-crystal X-ray diffraction studies. The electrochemical data suggest that cyclopentadienyl is the most electron-rich ligand followed by the C2B9 and then C2B10 systems, and ‘carbon-atoms-adjacent’ C2B10 system is more electron-donating than its ‘carbon-atoms-apart’ counterpart.