Bicyclic (alkyl)(amino)carbene stabilized zinc(0) complex with singlet biradicaloid ground state

Abstract

A storable bicyclic (alkyl)(amino)carbene (BICAAC) stabilized two coordinate zinc(0) complex [(BICAAC)2Zn] (2) was synthesized. DFT calculations reveal that BICAAC plays decisive role for imparting the stability of 2. This complex...

Ultra‐Long Lived Luminescent Triplet Excited States in Cyclic (Alkyl)(amino)carbene Complexes of Zn(II) Halides

“…[36] The zincÀ halide bond lengths progressively increase in a row Cl > Br > I (Figure 1), whereas the ZnÀ C carbene bonds of 1-3 show only minor variations and are very similar to those found for the NHC-and BIcAAC-based dimers mentioned above (~2.0 Å). [34][35][36] Dimers 1-3 are not soluble in aliphatic or aromatic hydrocarbons, or chlorinated solvents; however, they could be redissolved in acetonitrile for further characterization by multinuclear NMR spectroscopy (see Experimental Section). Coordination of the Me cAAC ligand to the Zn II ion leads to a significant upfield shift of the C carbene resonance in the 13 C{ 1 H} NMR spectra in CD 3 CN to ~250 ppm for 1-3 compared to 304.2 ppm of free Me cAAC.…”

“…The structures of 1 – 3 in the single‐crystalline solid state can be viewed as two pseudo‐tetrahedral {( Me cAAC)Zn(μ‐X) 2 X} units sharing one edge consisting of two bridging halides, with overall approximate D 2 symmetry. Only a few analogous Zn II carbene complexes have been reported in the literature to compare the structural parameters, which are [(IPr)BrZn(μ‐Br) 2 ZnBr(IPr)] [34] (IPr=1,3‐dimesityl‐imidazol‐4,5‐dihydro‐2‐ylidene), [(IPr’)ClZn(μ‐Cl) 2 ZnCl(IPr’)] [35] (IPr’=1‐mesityl‐3‐(methoxyethanyl)‐imidazol‐4,5‐dihydro‐2‐ylidene) and [(BIcAAC)ClZn(μ‐Cl) 2 ZnCl(BIcAAC)] (BIcAAC=bicyclic (alkyl)(amino)carbene) [36] . The zinc−halide bond lengths progressively increase in a row Cl > Br > I (Figure 1), whereas the Zn−C carbene bonds of 1 – 3 show only minor variations and are very similar to those found for the NHC‐ and BIcAAC‐based dimers mentioned above (∼2.0 Å) [34–36] …”

Ambiphilic singlet carbenes: Electron donors and acceptors

“…42f In 2021, Mandal et al reported a two-coordinate Zn (0) complex, (BICAAC) 2 Zn (Scheme 15). 43 Similar to (CAAC) 2 Zn, (BICAAC) 2 Zn is a singlet biradicaloid complex and was investigated by DFT calculations. (BICAAC) 2 Zn can be stored indefinitely at room temperature in an inert atmosphere and is stable for 24 h in degassed water (10 equiv.…”

Bicyclic (alkyl)(amino)carbene (BICAAC) as a metal-free catalyst for reduction of nitriles to amines

“…7 Recently, our group reported a BICAAC-stabilized Zn(0) complex and its reactivity with CO 2 and Ph 3 CCl. 8 In addition, BICAACs have attracted interest as a ligand in metal catalysed cross coupling reactions and terminal alkyne protoboration. 9,10…”