An ESR study of a hydrido-bridged trimetal cluster,Mn3(μ-H)3(CO)12?.

The anion radical of Mn₃(μ-H)₃(CO)₁₂ has been generated in frozen 2-methylte- trahydrofuran solutions by γ-irradiation and its ESR spectra have been analyzed. The spectra are consistent with D_3h geometry of the anion radical. The unpaired electron is accommodated in an a′₂; MO (D3h point group) constructed mainly from the manganese d AO's and with bent σ^★ characteristics with respect to the three MnMn bonds. The spin densities on the manganese d AO's and on the hydrogen 1s AO are estimated as 0.21 and ?0.03, respectively. The g tensor is explained using an MO diagram constructed from a model of the protonated metal-metal bond for the MnHMn bonds.