CO Fixation to Stable Acyclic and Cyclic Alkyl Amino Carbenes: Stable Amino Ketenes with a Small HOMO–LUMO Gap

Abstract

A quick fix: In contrast to cyclic diamino carbenes, stable alkyl amino carbenes react with CO to give stable ketenes (see scheme, top). Contrary to the acyclic versions, cyclic amino ketenes cannot escape from the destabilizing n–π donation of the nitrogen lone pair, which induces a diradical character and unusual optical (see scheme, bottom and photographs of crystals) and NMR spectroscopic properties.

Reactivity of a Stable Phosphinonitrene towards Small Molecules

“…For example, carbenes B and C are known to react with CO 2 , [10] CS 2 , [10] and P 4 . [11] The more nucleophilic and electrophilic carbenes C even react with CO, [12] H 2 , and NH 3 [13] to give the corresponding adducts, whereas NHCs B are inert under the same conditions. Studies dealing with aminonitrene D are limited to its decomposition reactions, [7b, 14] and its coordination behavior toward transition metals.…”

Revisiting the reactivity of different carbon bases: A theoretical study

“…(iii) If not then, what other criterion may be used to distinguish a carbene from carbone? To address these questions, quantum mechanical calculations have been carried out on the following closed-shell singlet carbenes (1-7) and carbones (8)(9)(10)(11)(12) as shown in Scheme 1. This study reveals that the distinction based on the previously proposed reactivity parameters [14,15] becomes blurred for electron rich carbones.…”

Reaktivität eines Dihydrodiborens gegen CO: Koordination, Insertion, Spaltung und spontane Bildung eines cyclischen Alkins

“…Among these are the cyclic and acyclic (alkyl)(amino)carbenes (cAACs and aAACs), in which the ylidenic carbon atom undergoes facile addition of H2 [15] as well as CO binding to afford the aminoketene product. [16] A bulky diarylgermylene reported by Power and co-workers was shown to undergo H2 addition as well as double CO insertion/coupling into both a Ge-C and an aryl-isopropyl bond of the ligand. [17] In the area of low-valent boron chemistry the dicoordinate cAACsupported aminoborylene reported by Stephan and Bertrand was shown to add H2 across the B-CcAAC bond and coordinate CO. [18] Scheme 1.…”