Synthesis of μ-Diborolyl Triple-Decker Complexes by Electrophilic Stacking. Similar Bonding Properties of Anions [CpCo(1,3-C₃B₂H₅)]⁻ and Cp⁻ toward Transition Metals

Triple-decker complexes with a bridging diborolyl ligand CpCo(μ-1,3-C3B2Me5)M(ring) (M(ring) = RuCp, 4; RuCp*, 5; Co(C4Me4), 6) were synthesized by electrophilic stacking of the sandwich anion [CpCo(1,3-C3B2Me5)]− with the [(ring)M(MeCN)3]+ cations. Structures of 4−6 were confirmed by X-ray diffraction. The electrochemical and spectroelectrochemical behavior of the complexes prepared was studied. DFT calculations of the redox potentials were also performed. Similar bonding properties of anions [CpCo(1,3-C3B2R5)]− and [C5R5]− (R = H, Me) toward [M(ring)]+ cations were established both experimentally (synthesis, electrochemistry, and X-ray diffraction) and theoretically (energy decomposition and Mulliken population analysis).