Homo- and Heteroleptic Complexes of Four-Membered Group 13 Metal(I) N-Heterocyclic Carbene Analogues with Group 10 Metal(0) Fragments

Abstract

A series of complexes between recently developed four-membered group 13 metal(I) heterocycles and group 10 metal(0) fragments have been prepared and structurally characterized. One prepared complex, [Pt{Ga[N(Ar)]2CNCy2}3] (Ar = C6H3Pri2-2,6; Cy = cyclohexyl), possesses the shortest Pt-Ga bonds yet reported, the covalent components of which are suggested by theoretical studies to have significant pi character.

Complexes of Four‐Membered Group 13 Metal(I) N‐Heterocyclic Carbene Analogues with Metal Carbonyl Fragments

“…These occur at higher wavenumbers in the gallium complex, which, in the absence of significant Ru→M π‐bonding, is indicative of the gallium heterocycle, 1 , being more nucleophilic than its indium counterpart, 2 . Indeed, this has been demonstrated in previous studies 12,14,15. The presence of two CO stretching bands in the infrared spectra of 5 and 6 suggests that the complexes exist as one isomeric form in the solid state.…”

“…Compounds 1 and 2 have been utilized as ligands in the preparation of a range of group 10 metal(0) complexes, e.g. [(dppe)Pt{M(Giso)} 2 ] [dppe = 1,2‐bis(diphenylphosphanyl)ethane] and [Pt{Ga(Giso)} 3 ],14 and platinum(II) complexes, e.g. cis ‐[Pt(Ar f ) 2 {Ga(Giso)} 2 ], trans ‐[Pt(Ar f ) 2 {In(Giso)} 2 ] and trans ‐[Pt(Ar f ) 2 {In(Giso)} 3 ] [Ar f = p ‐C 6 HF 4 or p ‐C 6 (OMe)F 4 ] 15.…”

“…These studies have revealed 1 and 2 to be poorly nucleophilic ligands [compared to group 13 metal(I) alkyl compounds]. In addition, there was some experimental and theoretical evidence for dπ–pπ back‐bonding associated with the covalent component of the Pt–Ga bonds of the homoleptic complex, [Pt{Ga(Giso)} 3 ] 14. Nevertheless, as the ionic component of these bonds dominates, the degree of back‐bonding was not thought substantial.…”

“Crowned” Univalent Indium Complexes as Donors? Experimental and Computational Insights on the Valence Isomers of EE′X4 Species

“…For example, the anionic compounds featuring E I centers stabilized by a-diimine ligands and the related neutral complexes featuring b-diketiminate ("nacnac") ligands provide Group 13 reagents that can be used as donors. [17,23,24] It is perhaps worth noting that such Group 13 donors can behave as pure s-donors in complexes with main group Lewis acids and, depending on the nature of the ligand attached to the Group 13 element, transition-metal complexes of such donors may exhibit metal to ligand pbackbonding in addition to s-donation. [25][26][27][28] Of somewhat more fundamental interest have been the homonuclear complexes in which both the donor and acceptor atoms are Group 13 elements because these species may be considered as valence isomers of dinuclear compounds containing the elements in the + 2 oxidation state.…”

Insights into the Factors Controlling the Origin of Activation Barriers in Group 13 Analogues of the Four-Membered N-Heterocyclic Carbenes

“…Therefore, these theoretical works strongly suggest that such four-membered heterocyclic NHCs with a central E element can be considered good σ-donor and weak π-acceptor ligands. 20 − 23 Based on these works, much experimental effort has been devoted to studying the structural and spectroscopic properties of the coordinated complexes arising from these four-membered group 13 NHC species with transition-metal fragments. 24 − 27 Nevertheless, so far neither experimental nor theoretical studies have been performed on the reactivity of these four-membered group 13 NHC analogues toward small organic molecules, let alone on comprehending the root of their reactivity.…”