Mono‐ and Dicoordinate Germanium(0) as a Four‐Electron Donor

Abstract

We report the synthesis and isolation of molecular iron germanide motifs in the stoichiometry of Fe Ge and Fe Ge, which are stabilized by the coordination of N-heterocyclic carbene (NHC) and carbon monoxide (CO) ligands. NHCiPr2Me2 ⋅Ge[Fe(CO) ][Fe (CO) ] (NHCiPr2Me2 =1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene), a germanium(0) ligand with just one NHC as an auxiliary ligand, assumes a bridging coordination mode between a mononuclear [Fe(CO) ] and a dinuclear [(CO) FeFe(CO) ] unit with rapid exchange between the two binding modes in solution. The electronic structure of this species is analysed by NBO and ELF calculations with DFT methods, as well as the mechanistic details of its fluxional coordination behaviour. Treatment of NHCiPr2Me2 ⋅Ge[Fe(CO) ] [Fe (CO) ] with the sterically less demanding NHCMe4 (NHCMe4 =1,3,4,5-tetramethylimidazol-2-ylidene) leads to a dinuclear iron complex (NHCMe4 ) Ge[Fe(CO) ] that contains a bridging germylone ligand with two stabilizing NHC equivalents.

Germylone-bridged bimetallic Ir and Rh complexes

“…13 Recently, the group of Jana and Rzepa prepared the first dicoordinate germylone-iron complex C by the transformation of the NHC-digermanium(0)-iron complex. 14 Note that both synthetic routes to the germylone-iron complexes B and C are not straightforward from the isolable germylones. In contrast, Driess and co-workers reported the direct complexation between an isolable germylone and excess AlBr3 affording bis(AlBr3)-germylone adduct D. 15 Recently, we have reported the isolation of germylone 1 stabilized by a bidentate imino-N-heterocyclic carbene, which can readily react with M(CO)5(thf) (M = Cr, Mo, W) to generate the corresponding mono-coordinate germylone-metal complexes [1⦁M(CO)5] (E).…”

An Approach to Carbide-Centered Cluster Complexes

“…Theoretical studies have dismissed bonding descriptions with metal–metal bonds in Fe 2 (CO) 9 . Along these lines, Fe 2 (CO) 8 (μ-L) complexes exhibit a large range of intermetallic distances (μ-CH 2 : 2.507(1) Å, μ-CF 2 : 2.5816(6) Å, μ-[Ge 0 ]: 2.7596(18) Å). , …”

Base-stabilized formally zero-valent mono and diatomic molecular main-group compounds

“…135 Further, the reaction of compound 112 with Fe 2 (CO) 9 resulted in a Ge(0) adduct 113b in a low yield (Scheme 32). 136 Compound 113b can be synthesized in a good yield from the reaction of [NHC iPr2Me2 •GeCl 2 •Fe(CO) 4 ] ( 111) with excess Fe 2 (CO) 9 (Scheme 32). The single-crystal X-ray structural data of 113b revealed the presence of an NHC i Pr 2 Me 2 coordinated Ge(0) motif, and the germanium center is coordinated to Fe (CO) 4 and Fe 2 (CO) 8 in a terminal (σ-type) and bridging (π-type) mode, respectively.…”

“…Although, isolation and characterization of 114 was not successful due to stability issues and insufficient solubility differences between 114 and 115. 136 The first isolable NHC-stabilized Ge(0) complex with a single germanium atom was reported by Driess and co-workers in 2013. 137 An equimolar reaction of bis-NHC with GeCl 2 •dioxane resulted in Ge(II) salt [bis-NHCGeCl] + Cl − (116) in an excellent yield.…”