The tri–μ–hydrido–bis[(η5–C5Me5)aluminum(III)] theoretical study, the assets of sandwiched M2H3 (M of 13th group elements) stability

The stability of the tri–μ–hydrido–bis[(η5–C5Me5)aluminum], Cp*2Al2H3, 1 is studied at B3LYP/6–311+G(d,p), CCSD(T)//B3LYP/6–311+G(d,p) and MP4//B3LYP/6–311+G(d,p) levels. The coordination between Al2H3 entity and both C5(CH3)5 groups is ensured by strong electrostatic and orbital interactions. The orbital analysis of the interacting fragments shows that Al2H3 acceptor, which keeps its tribridged structure, implies the vacant \( \left( {{\text{a}}_1^\prime } \right) \) and five antibonding (\( a_2^{\prime \prime } \), e′ and e″) molecular orbitals to interact with two orbitals mixtures, b1 and e" of the donors (C5Me5). When we take into account the solvent effect, the computation shows that 1 seems to be stable in condensed phase with a tribridged bond between the Al atoms [Cp*Al(μ-H)3AlCp*], whereas in the gas phase, the monobridged Cp*AlH(μ-H)AlHCp* 4 is slightly favored (4 kcal mol−1). We propose that 1 could be prepared thanks to Cp*Al (2) and Cp*AlH2 (3) reaction in acidic medium. The experimental treatment of this type of metallocenes would contribute to the development of the organometallic chemistry of 13th group elements.