Synthesis and Unexpected Reactivity of Germyliumylidene Hydride [:GeH]~+ Stabilized by a Bis(N-heterocyclic carbene)borate Ligand

摘要

Employing the potassium salt of the monoanionic bis(NHC)borate 1 (NHC = N-Heterocyclic Carbene) enables the synthesis and isolation of the bis(NHC)borate-stabilized chlorogermyliumylidene precursor 2 in 61% yield. A Cl/H exchange reaction of 2 using potassium trisec.-butylborhydride as a hydride source leads to the isolation of the first germyliumylidene hydride [HGe:~+] complex 3 in 91% yield. The Ge(Ⅱ)-H bond in the latter compound has an unexpected reactivity as shown by the reaction with the potential hydride scavenger [Ph_3C]~+[B(C_6F_5)_4]~-, furnishing the corresponding HGe: → CPh_3 cation in the ion pair 4 as initial product. Compound 4 liberates HCPh_3 in the presence of 3 to give the unusual dinuclear HGe: → Ge: cation in 5. The latter represents the first three-coordinate dicationic Ge(Ⅱ) species stabilized by an anionic bis(NHC) chelate ligand and a Ge(Ⅱ) donor. All novel compounds were fully characterized, including X-ray diffraction analyses.