Coordination Chemistry of Main Group Metals with Organic Isocyanides

Abstract

This review deals with advances in the chemistry of organic isocyanide complexes of the main group metals. Isocyanides acting as functional groups show a great dichotomy between nucleophilic and electrophilic characters, which diversifies the course of different multicomponent reactions. The carbon and nitrogen centers can serve as the donor atom in different metal isocyanide frameworks. Along with the variation in ligation properties and different coordination modes, the metalated isocyanides emerge as a well-established organometallic system with an effective synergistic mechanism, making them chemically and synthetically significant to chemists. However, the linear arrangement of the MÀ C=NÀ R induces the formation of multinuclear isocyanide complexes of good thermal stability, which draws the metalated isocyanides into the focal point of advanced reactivity and catalytic studies. A thorough literature survey on molecular main group metal complexes with organic isocyanides has been provided.

Evidence for Carbene Intermediates in Isocyanide Homologation by Aluminium(I)

“…The formation of 3 via an isocyanide dimerization/CÀ H activation sequence is peculiar, and similar metal-mediated transformations have hitherto only been reported by Cui et al. [19,37] Both the AlÀ C65 and AlÀ N3 bond lengths (2.027(2) and 1.8272(19) Å, respectively) in 3 are similar to those reported by Cui et al ( 2.003(5) and 1.818(4) Å, respectively). Comparing the 1 H NMR spectra of 3 and 13 Clabeled 3 reveals that the proton within the AlNC2 ring resonates at 5.24 ppm (J CÀ H = 142.6 and 2.0 Hz, Figure S24; for the 13 C NMR spectrum, see Figure S26).…”

“…Unlike other low-valent main group centers, a coordination complex of Al I with an isocyanide has not yet been isolated. [19] Whereas attempts to pinpoint this intermediate by 1 H and 13 C NMR spectroscopy at À 70 °C failed (Figures S19 and S20), quantum chemical calculations (DLPNO-CCSD(T)/def2-TZVPP//r 2 SCAN-3c with correction for solvation in THF, Figure S92; cf. Figure 6 for PhNC) suggest that end-on coordinated 1-η 1 -BhpNC (ΔG = 0 kJ mol À 1 ) is more stable than the side-on coordinated 1-η 2 -BhpNC (ΔG = + 45 kJ mol À 1 ).…”

“…[15][16][17][18] Isocyanides are isoelectronic with carbon monoxide and, thus, find extensive application in related chemical transformations. [19] As for FT-type homocouplings, isocyanides may oligomerize (e.g., trimerization, [20][21][22][23] tetramerization, [24][25][26] and pentamerization [27,28] ) or even polymerize [29] in the presence of suitable catalysts. Whereas isocyanide-derived free carbenes have been proposed in some of these CÀ C bond formation processes, [21,23,24,26] as far as we know, they have never been isolated or trapped.…”

Bismuth Cations: Fluoride Ion Abstraction, Isocyanide Coordination, and Impact of Steric Bulk on Lewis Acidity

“…[38] In addition to the rich portfolio of organic compounds that can be derived from isocyanides, their coordination chemistry towards main group metals has been investigated in some detail. [39] In contrast, only little is known about the chemistry of isocyanides with heavy main group Lewis acids in general and group 15 species in specific. For instance, the insertion of isocyanides into BiÀ B and BiÀ N bonds has been reported, exploiting the high reactivity of boryl anions [40] and ring-strained BiC 2 N cycles.…”

Über Carbenintermediate in der AlI vermittelten Homologisierung von Isocyaniden

“…Solche metallinduzierten Transformationen sind bisher nur von Cui et al. beschrieben worden [19,37] . Die Bindungslängen Al−C65 sowie Al−N3 in 3 (2.027(2) bzw.…”