A digermylene (LGeI–GeIL) on an N-heterocyclic carbene–fluorenyl hybrid ligand (L) and its oxidation by TEMPO and Ph2E2 (E = S, Se)

Abstract

A hybrid N-heterocyclic carbene (NHC)–fluorenyl ligand (L) supported Ge^IICl complex ([LGeCl]; 1) has been made from GeCl₂(dioxane) and [LK]_n. Compound 1 is reduced by Jones’ Mg^I₂ dimer [(^MesNacnacMg)₂] (^MesNacnac = [{(Mes)NCMe}₂CH]⁻; Mes = 2,4,6-Me₃-C₆H₂) to give the digermylene [LGe^I–Ge^IL] (2) with a gauche-bent conformation. Compound 2 is oxidized by TEMPO (2,2,6,6-tetramethylpiperidinyloxy) and Ph₂E₂ (E = S, Se) to give [LGe(TEMPO)] (3) and [LGeEPh] (E = S (4), Se (5)), respectively. Overoxidation of 2 by Ph₂Se₂ to give a mixed-valent trinuclear species [{(PhSe)₂Ge^II}₂(μ-L)₂Ge^IV(SePh)₂] (6) is also noted. Besides, precursor 1 is converted into [LGeMe] (7) and [LGeOSiPh₃] (8) by treating it with MeMgBr and KOSiPh₃, respectively. However, none of these compounds leads to a desired [LGeH] species. Also, interestingly, Cl-abstraction from 1 by AgSbF₆ fails and it rather forms a 2 : 1 adduct [(LGeCl)₂Ag][SbF₆] (9).