The nature of Re-Re bonding in Re2(µ-Ph2PCH2PPh2)(S2CNEt2)4 complex, including its neutral (10) and two oxidized (1+ and 12+) species, was explored utilizing state-of-the-art quantum chemical methodologies within density functional theory (DFT) and complete active space self-consistent field (CASSCF). Our results show that the ground state electron configuration of the 10 is σ^2 π^4 δ^2 δ^(*2) with an effective bond order (EBO) of 2.73 computed with CASSCF. The oxidation discloses an electron removal from a metal-based orbital, giving 1+ and 12+ with an EBO of 2.71 and 2.64, respectively. The relative similarity in EBO values among neutral and oxidized species suggests that the oxidation processes have almost no effect on the Re-Re bond strength even though electrons removal from metal-based orbitals because the electrons that occupied the δ components of Re-Re bonds in 1+ and 12+ localized on the two Re ions, thus, they were excluded from EBO estimation.
Written more academically.