Durch ein N‐heterocyclisches Carben koordinierte neutrale und kationische schwere Cyclopropylidenanaloga

Abstract

Cyclopropyliden ist ein kurzlebiges Zwischenprodukt der Allen-Propin-Cyclopropen-Isomerisierung. Der Einbau schwerer Gruppe-14-Elemente in das Cyclopropyliden-Grundgerüst war bisher auf den formalen Austausch des Carbenkohlenstoffatoms durch ein einzelnes basenstabilisiertes Silicium(II)-Zentrum beschränkt. Hier berichten wir über die Synthese und Charakterisierung von NHC-koordinierten schweren Cyclopropylidenanaloga (Si 2 GeR 3 X und Si 3 R 3 Br; X = Cl, Mesityl; R = Tip = 2,4,6-iPr 3 C 6 H 2 ), bei denen der Dreiring ausschließlich aus Silicium und Germanium besteht. Im Falle des chlorsubstituierten Si 2 Ge-Analogons wird durch eine NHC-induzierte Chloridabspaltung ein stabiles, schweres, kationisches Cycloprop-1-yl-2-ylidenanalogon erhalten.

A Stable Heterocyclic Amino(phosphanylidene‐σ4‐phosphorane) Germylene

“…[27] An original NHC-stabilized germacyclopropylidene was also recently described. [28] Of particular interest, the molecular structure of 4 shows unusually small Ge1-P3-Ge2 [89.904(7)8 8]a nd P2-P3-Ge2 [84.078(9)8 8]a ngles,a nd very short interatomic distances (Ge1-Ge2:3 .10 , P2-Ge2: 3.09 ). Thei nteratomic distances are shorter than the sum of the van der Waals radii (Ge-Ge:4.6 , P-Ge:4.1 ), thus suggesting the presence of the interactions between either Ge1 and Ge2 or P2 and Ge2.…”

SiSi Double Bonds: Synthesis of an NHC‐Stabilized Disilavinylidene

“…[17] Notably,a nN HC-stabilized disilavinylidene was recently presumed to be one of the intermediates during the formation of an NHC-stabilized trisilacycloprop-1-ylidene, but no experimental evidence was provided. [18] Also recent theoretical work predicted that NHC-stabilized silavinylidenes and the heavier homologues should be stable and isolable molecules. [19] We set out to combine the well-known Lewis base character of ECl 2 (NHC) (E = Si, Ge) [8b, 20] with the electrophilicity of multiply bonded low-valent silicon compounds,s uch as the 1,2-dihalodisilenes, [6c, 12d, 21, 22] and envisaged that this approach might lead to new interesting silicon chemistry.Herein, we report the realization of this approach with the syntheses and full characterization of an unprecedented NHC-stabilized bromo(silyl)silylene and its reduction product, an NHC-stabilized disilavinylidene.…”

σ,π‐Conjugated Bis(germylene) Adducts with NHC and CAACs

“…The slight upfield shift compared to the parent tetragermadiene 1 (4.27 ppm) [58] and silyldigermenes and ‐germylenes in general (13.5 to −2.7 ppm) [27,58,61,62] is in line with a certain donation of the germanium‐centered lone pairs of 4 to σ*‐orbitals at the SiMe 2 bridge. The characteristic 1 H and 13 C{ 1 H} signals of the Me 2 IPr methine groups (5.54 ppm) and the carbenic carbons (177.08, 177.00 ppm) confirm the coordination of Me 2 IPr to the germanium centers [19,20,23,27,28,63–67] . The GeTip 2 /Me 2 IPr adduct shows similar 1 H NMR septets at 5.64 and 5.34 ppm and a 13 C{ 1 H} resonance at 176.94 ppm for the coordinated Me 2 IPr.…”

“…The characteristic 1 H and 13 C{ 1 H} signals of the Me 2 IPr methine groups (5.54 ppm) and the carbenic carbons (177.08, 177.00 ppm) confirm the coordination of Me 2 IPr to the germanium centers. [19,20,23,27,28,[63][64][65][66][67] The GeTip 2 /Me 2 IPr adduct shows similar 1 H NMR septets at 5.64 and 5.34 ppm and a 13 C { 1 H} resonance at 176.94 ppm for the coordinated Me 2 IPr.…”