Two‐Coordinate Cu(I) and Au(I) Complexes Supported by BICAAC and CAAC Ligands

Abstract

Two‐coordinate Cu(I) and Au(I) complexes supported by bicyclic (alkyl)(amino)carbene, [BICAAC‐CuCl] (1), [BICAAC‐CuI] (2), [(BICAAC)2Cu]+[PF6]– (3) and [(BICAAC)2Au]+[AuCl2]– (6) have been synthesized. The reaction of cyclic (alkyl)(amino)carbene, CAACcy with CuCl afforded [CAACcy‐CuCl] (4) and its further reaction with KPF6 gave [(CAACcy)2Cu]+[PF6]– (5). Complexes 1–6 have been characterized by multinuclear NMR, IR and UV‐Vis., spectroscopic method and high‐resolution mass spectrometry (HRMS). Single crystal X‐ray structure of heteroleptic complexes 1 and 4 and homoleptic complexes [(BICAAC)2Cu]+[CuI2]– (2’), 3 and 6 have also been determined. The crystal structure of these complexes confirmed linear two‐coordinate geometry around the metal centers. In the solid‐ state, complexes 1, 2’, 4 and 6 displayed C−H⋯M (M=Cu, Au) and weak non‐covalent C−H⋯X (X=Cl, I) and C−H⋯H−C interactions. Computational calculations correlate well to the experimentally observed geometry and help elucidate the absorption characteristics type of transitions and the frontier orbitals involved in them.

Recent Advances in the Domain of Cyclic (Alkyl)(Amino) Carbenes

“…Additionally, coordinate low-valent Cu(I) and Au(I) have also been stabilized by BicAAC. [114] In order to synthesize (cAACs) 2 M complex (M=Mn and Zn), we initially prepared an adduct (Me 2 À cAAC)MCl 2 by reacting Me 2 À cAAC (44) with anhydrous M(II)Cl 2 in 1 : 1 molar ratio in THF (Scheme 22 and 23). Here (Me 2 À cAAC)ZnCl 2 (45) was reduced in the presence of two equivalents of KC 8 to form dark blue colored (Me 2 À cAAC * )Zn II (46) (Me 2 À cAAC * = radical anion on carbene carbon atom) or dark purple solution of (Me 2 À cAAC) 2 Mn in low yield.…”

“…This is quite a remarkable observation. Additionally, coordinate low‐valent Cu(I) and Au(I) have also been stabilized by BicAAC [114] …”

Synthesis and Characterization of Novel PEPPSI type Pd–BICAAC Complexes

“…Although the literature of BICAAC-complexes are still limited, some transition metal BICAAC complexes have already been reported: copper-group metals (Cu, Ag, and Au) were complexed with BICAAC ligands, [25][26][27] and bis-BICAAC complexes were prepared giving zinc(0) 28 and palladium(II) 29 complexes; the latter was found to be an effective catalyst in crosscoupling reactions. 4…”

Coordination modulated on-off switching of flexibility in a metal–organic framework

“…We note that Cu(I) complexes are known to readily access a digonal geometry. 35,[41][42][43][44][45][46][47]48 Indeed, density functional theory (DFT) calculations performed on representative molecular subunits reveal that there is a slight energetic preference for the digonal 1•[CuCl]unlocked over the trigonal planar 1•[CuCl] species (~5 kJ/mol). However, for the analogous Br and I species, the trigonal planar coordination is thermodynamically favoured (Figures S7, S8).…”