Strong electronic coupling between dimolybdenum units linked by the N,N′-dimethyloxamidate anion in a molecule having a heteronaphthalene-like structure

Very strong electronic communication, manifested in a K_c value of ca. 10⁹, has been found in a system of three compounds separated by one electron oxidation where each compound contains two metal-metal bonded Mo₂ⁿ⁺ units linked by a dimethyloxamidate anion, CH ₃N(O)C-C(O)NCH₃^2-. The Mo-Mo distances increase as the oxidation state increases and the bond order decreases, while the diamagnetic, doubly oxidized species becomes essentially planar and resembles a naphthalene molecule. Calculations at the DFT level indicate that a strong transition in the near-IR region, shown by the singly oxidized and paramagnetic species, is best described as a HOMO-1 → SOMO transition.