This work presents a new family of zincacarborane complexes synthesized from ZnMe2 and C2B9H13, using neutral two-electron donor ligands: N-heterocyclic carbenes (NHCs) yield the first closo-12-vertex half-sandwich zincocenes, (NHC) Zn (C2B9H11) (1-3), while bulkier NHCs form slipped bis-dicarbollide salts (4-5). Use of pyridine leads to the macropolyhedral dimer (6) with a planar Zn2B2 motif, and triphenylphosphine gives a V-shaped η3-borallyl complex (7). Structures have been confirmed by single-crystal X-ray diffraction and NMR spectroscopy. Computational studies (DFT and QTAIM) show predominantly ionic Zn-dicarbollide bonding with notable polar covalent character. Apparent Zn···Zn interactions are weak electrostatic contacts, and metal-ligand bonding is exclusively to boron atoms. Together, these findings broaden the structural and electronic landscape of zincacarboranes, challenge assumptions about d10 metal-carborane bonding, and offer a new platform for exploring group 12 metallacarborane reactivity.
Flanagan et al. (Fri,) studied this question.