Ge(0) Compound Stabilized by a Diimino-Carbene Ligand: Synthesis and Ambiphilic Reactivity

Abstract

The germylone dimNHCGe (5, dimNHC = diimino Nheterocyclic carbene) was successfully prepared via the reduction of the germanium cation [dimNHCGeCl] + with KC 8 . The molecular structure of 5 was unambiguously established by both NMR spectroscopy and single-crystal X-ray diffraction. The reactivity of 5 was investigated, revealing that it undergoes oxidative addition of HCl, CH 3 I, and PhI, accompanied by an unusual migration of the H, Me, and Ph groups from germanium to the carbene ligand. Related chemistry was also observed with C 5 F 5 N, which results in the migration of the fluorinated pyridine moiety to the carbene ligand. Compound 5 also undergoes cycloaddition with tetrachloro-o-benzoquinone to afford a Ge(IV) adduct.

Changing the Reactivity of Zero‐ and Mono‐Valent Germanium with a Redox Non‐Innocent Bis(silylenyl)carborane Ligand

“…Owing to the peculiar bonding situation and the zero‐valent nature of the central atoms, tetrylones may exhibit a versatile reactivity with access to new types of low‐valent Group 14 element compounds. Utilizing iminopyridines, [10, 11] iminocarbenes, [12, 13] carbenes, [14–19] silylenes, [20–24] and germylenes [25, 26] as supporting σ‐donor ligands L, various examples of carbones, [14, 15] silylones, [16, 18, 20, 22–24, 26] germylones, [11–13, 17, 19, 21, 25] and stannylones [10] have been synthesized and structurally characterized. However, compared to carbenes and related metallylenes, the number of isolable tetrylones is still limited and their reactivity much less explored.…”

Entering new chemical space with isolable complexes of single, zero-valent silicon and germanium atoms

“…49 Very recently, the group of Nikonov succeeded in the synthesis of the germanium(0) complex H, in which the germanium atom is stabilised by a tridentate diimino-NHC (dimNHC) ligand. 23 In contrast to the bis(imino)pyridine-supported Ge 0 G, complex H exhibits some interesting reactivity towards organic substrates with the involvement of the NHC-carbon(II) atom [C(II) oxidised to C(IV), vide infra].…”

“…Similarly, utilising the germylone K (Chart 2), Nikonov and co-workers explored very recently the reaction with GeCl 2 (dioxane), giving rise to the corresponding [GeCl] + complex with [GeCl 3 ] À as counterion. 23…”

“…of MeOTf to afford the Ge(IV) species I-2, shown by Kinjo and co-workers. 75 In the case of the (dimNHC)Ge H developed in 2020 by Nikonov, 23 the carbene donor of the tridentate ligand is involved in H/C-X (X = halogen) activation. In reactions with HCl, MeI, PhI and C 5 F 5 N, a Ge-X bond and a C-H or C-C bond form at the carbene-C to give the new species H-1-4 (Chart 3) respectively.…”

“…18 In the same year, our group reported the first cyclic silylone 1 (Chart 2) with the central silicon atom coordinated by a neutral chelating bis(NHC) ligand, 19 followed by the analogous germylone 2 (Chart 2, also known as germadicarbene) with the same bis(NHC) ligand. 20 Meanwhile, the isolation of cAAC-supported acyclic germylone F (Chart 2) was achieved by Roesky, Zhu, Stalke, and Andrada, 21 and subsequently the germanium(0) complexes G, 22 H, 23 and I 24 ligated by imino containing systems were obtained by Nikonov and Kinjo, respectively.…”