The Preparation of Complexes of Germanone from a Germanium μ‐Oxo Dimer

Abstract

Complexes of germanone containing formal Ge=O→M bonds (M=Zn, B, Ge, Sn) were isolated and characterized. The compounds were prepared through a novel synthetic route using a germanium μ-oxo dimer 3 as the starting material. This method circumvents the need to employ germanones to prepare complexes of germanones.

Isolation of a Cyclic (Alkyl)(amino)germylene

“…The Ge-S bond distances ( 6a : 2.2462(13) Å and 2.2406(13) Å, 6b : 2.231(3) Å and 2.237(3) Å) are in the range reported of Ge-S single bonds (2.17–2.25 Å) [61], and longer than the Ge=S double bond length of 2.049(3) Å in [Tbt(Trip)Ge=S] (Tbt = 2,4,6-{(Me 3 Si) 2 CH} 3 C 6 H 2 , Trip = 2,4,6- i Pr 3 C 6 H 2 ) [62]. To investigate the reaction mechanism, we attempted to quench the reaction intermediate employing Lewis bases (pyridine, Me 3 N, Ph 3 P and Et 3 N) and Lewis acids (BPh 3 and B(C 6 F 5 ) 3 ) [63,64,65]. However, none of them afforded any trapped products, and only the formation of 6a and 6b were observed.…”

New Perspectives for Aminotroponiminates: Coordination Chemistry, Redox Behavior, Cooperativity, and Catalysis

“…In recent years, it has been demonstrated that ATI ligands are well‐suited for stabilizing heavy analogs of carbon oxo compounds. With the Ge IV complexes [GeO(ATI i Bu/ i Bu ) i Pr(LA)] ( 45‐LA ) were the first Lewis acid adducts of a heavy ketone analog isolated and fully characterized (Scheme a; LA = Lewis acid) . DFT calculations confirmed a decreased ATI Ge–O bond order for 45‐LA [Wiberg bond indices (WBI): 0.60–0.72] compared to that in the theoretically investigated parent germanone 45 (WBI: 1.08).…”

Donor–acceptor-stabilised germanium analogues of acid chloride, ester, and acyl pyrrole compounds: synthesis and reactivity

“…Strategies that utilise tailor-made ligands and/or provide donor–acceptor stabilisation to M/O atoms have been applied to address the aforementioned problems and have yielded various stable compounds containing MO bonds 7–11. Thus, silanones (silaketones) and germanones (germaketones) with formal SiO and GeO bonds, respectively, were successfully isolated, and the variety of silanones exceeds that of the germanones 7–10. In addition to silanones, silicon analogues of aldehyde, ester, amide, formyl chloride, carboxylic acid, and acid anhydride compounds were also synthesised via various methods mainly by the groups of Driess, Roesky, Baceiredo, and Kato 12.…”

“…12 a Surprisingly, such analogues of germanium [LGe(O)Y] [L = a monoanionic ligand; Y = H (germaaldehyde), Cl (germaacid chloride), OR (germaester), NR 2 (germaamide), OH (germacarboxylic acid), and (OGe(O)L) germaacid anhydride] are not yet known, perhaps due to the difficulty in adding an electron-withdrawing Y atom/group to the germanium atom in light of the already heavily polarised GeO bond. Owing to our continued interest in the chemistry of germanium, we were able to isolate the Lewis acid (LA) complexes (i-Bu) 2 ATIGe(i-Pr)O → LA (LA = B(C 6 F 5 ) 3 ( IV ), ZnCl 2 ( V ), SnCl 2 ( VI ), and GeCl 2 ( VII )) of a germanone10 starting from a germanium-μ-oxo dimer [ATI = aminotroponiminate, a monoanionic bidentate ligand]. We now understand that this synthetic protocol is exploitable for the synthesis of hitherto unknown germaacid chlorides and germaesters.…”

“…However, all of these reactions were typically unsuccessful until now (see the ESI‡ for details). Surprisingly, the germanium-μ-oxo dimer {(i-Bu) 2 ATIGe(i-Pr)(μ-O)} 2 ( D ) with Ge–i-Pr bonds was insensitive to the nature of the Lewis acid used 10. Thus, it reacted smoothly with B(C 6 F 5 ) 3 , ZnCl 2 , SnCl 2 , and GeCl 2 to afford the donor–acceptor-stabilised germanones IV , V , VI , and VII , respectively 10…”