Our paper on Ni-pentalene complexes, which we previously posted on ChemRxiv, has now been published in JACS. Congratulations to Riina, Takefumi, and everyone involved in the project! 🎉 pubs.acs.org/doi/10.1021/... Please check it out - it’s open access.
A Persistent Ni(0)–Pentalene Complex with High Fluxionality: Does Stronger Antiaromaticity Promote Metal–Ligand Interactions?
Despite the long-standing use of transition metal complexation for stabilizing antiaromatic hydrocarbons, the underlying factors that govern their coordination behavior remain unclear. A Ni(0) complex, [Ni(cod)(1)], featuring a benzothiophene-S,S-dioxide-fused pentalene ligand, was synthesized and characterized, and compared to a benzothiophene-fused analogue, [Ni(cod)(2)], which bears a more antiaromatic yet less electron-accepting pentalene ligand. Single-crystal X-ray diffraction, X-ray absorption spectroscopy, and variable-temperature NMR, combined with computational analyses, reveal that the enhanced stability of [Ni(cod)(1)] arises primarily from substantial π-back-donation facilitated by strongly electron-withdrawing SO2 groups that lower the LUMO energy of 1. Comparisons to [Ni(cod)(2)] further demonstrate that a more antiaromatic core does not necessarily lead to stronger coordination to the Ni center. Surprisingly, the robust [Ni(cod)(1)] complex is fluxional in solution; the Ni center migrates reversibly between the two five-membered rings of the pentalene ligand via a bond shift mechanism.
pubs.acs.org
