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 Kc 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 Mo-2(n+) units linked by a dimethyloxamidate anion, CH3N(O)C-C(O)NCH32-. 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.