Donor-Stabilized Antimony(I) and Bismuth(I) Ions: Heavier Valence Isoelectronic Analogues of Carbones

Isolation of two-coordinate compounds of heavier Group 15 elements in low oxidation state is challenging due to the preferential formation of dimers or oligomers. Herein, we report the first examples of donor-stabilized two-coordinate Sb­(I) and Bi­(I) ions. The reduction of antimony and bismuth trihalides with KC8 in the presence of cyclic alkyl­(amino) carbene (cAAC) afforded Sb­(I) and Bi­(I) cations in the form of triflate salts [(cAAC)2Sb]­[OTf] (1) and [(cAAC)2Bi]­[OTf] (2). Compounds 1 and 2 belong to a new class of acyclic cations of Group 15 with eight valence electrons and are heavier valence isoelectronic analogues of carbones. Both compounds are isolated and well-characterized by NMR spectroscopy, cyclic voltammetry, single-crystal X-ray diffraction, and computational studies.