A Fischer Carbene within an Arduengo Carbene

Abstract

A Fischer carbene complex within the N‐heterocyclic carbene skeleton is present in MnI/AuI heterometallic compounds that were synthesized from an acyclic diaminocarbene complex, through a translocation process of metallic ions under basic conditions and subsequent alkylation with methyl triflate (see scheme; bipy=bipyridyl, [Mn]=[Mn(CO)2(bipy)]).

Supramolecular aggregation in dithia-arsoles: chlorides, cations and N-centred paddlewheels

“…14 Despite the poorer donor ability, a number of examples of metal-arsenium com-plexes have been reported affording structures homologous to Fischer carbenes. 15,16 One of the earliest dithia-arsolidinium cations (3a, Scheme 1) to be described was reported by Burford in 1989 but its solid-state structure was never eluci-dated. 17 Whilst dithiaarsolidinium cations have been shown to exhibit Lewis acidic properties towards both pyridine and triphenylphosphine, 8,18 more recent studies into arsenic- In the current report we describe a series of structural studies on the dithia-chloro-arsoles, 1 and 2 (Scheme 1).…”

An Ambidentate Janus‐Type Ligand System Based on Fused Carbene and Imidato Functionalities

“…These are illustrated, for example, by heterobimetallic complexes of 1,2,4-triazolyl-3,5-diylidenes (A), [4] benzobis(imidazolylidene)s (B), [5] 4-phosphinoimidazol-2-ylidenes (C) [6] and 1,3-imidazol-2,4-ylidenes (D) [7] as well by the gold(I) complex E supported by a Fischer carbene-containing NHC (Scheme 1). [8] In a logical continuation of our original work on the construction of modular anionic and neutral NHCs incorporating a malonate backbone, [3f, 9] which are receiving growing attention, [10] we reasoned that, based on the isolobal analogy between "CÀR' group and "N' atom, it would be of interest to synthesize the N-heterocyclic carbene imidNHC (Scheme 2) incorporating an imidato backbone (a biologically relevant functionality) [11] susceptible to act as a labile donor group toward various transition metals. [12] The mesoionic precursor 1,3-dimesityl-s-triazine-4,6-dione 2·H was prepared in high yield through decisive modifications of a procedure which had been previously found to give only poor yields of analytically impure samples of the compound.…”

“…Further synthetic possibilities and applications of this fascinating new carbenic (5), C3ÀN3 1.348(6), C2À01 1.215(4), C3ÀO2 1.208(5). Selected bond angle [8]: C1-Au1-P1 173.29 (8).…”

Strong electron-donating metalla-N-heterocyclic carbenes

“…13 Recently, our group has described the synthesis of unique NHC-gold complexes containing a metal atom within the NHC 35 skeleton (C). 14 In the present work it has been found a new experimental protocol for the formation of metalla-N-heterocyclic carbenes (MNHCs) 15,16 and proved for the first time its strong electron-donor character by comparison with classical imidazol-2-ylidenes, based on the variation of the ν(CO) and ν(CN) doubly deprotonated form of the ADC to bind ruthenium in a chelating manner. A substitution reaction of the chloride ligand in 4 by isocyanide, using TlPF 6 as halogen abstractor, yields the cationic complex 5, which is finally transformed to 6 by treatment with HCl.…”