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Pyridine-alkoxide (pyalk) ligands that support transition metals have been studied for their use in electrocatalytic applications. Herein, we used the pyalk proligands diphenyl(pyridin-2-yl)methanol ([H]PhPyalk, L1), 1-(pyren-1-yl)-1-(pyridin-2-yl)ethan-1-ol ([H]PyrPyalk, L2), 1-(pyridine-2-yl)-1-(thiophen-2-yl)ethan-1-ol ([H]ThioPyalk, L3), and 1-(ferrocenyl)-1-(pyridin-2-yl)ethan-1-ol ([H]FePyalk, L4) to synthesize CuII complexes that vary in nuclearity and secondary coordination sphere. Also, the proligand 1-(ferrocenyl)-1-(5-methoxy-pyridin-2-yl)ethan-1-ol ([H]FeOMePyalk, L5) was synthesized with a methoxy substituted pyridine; however, the isolation of a CuII complex ligated by L5 was not possible. Under variable reaction conditions, the pyalk ligands reacted with CuII precursors and formed either mononuclear or dinuclear CuII complexes depending on the amount of ligand added. The resulting complexes were characterized by single crystal X-ray diffraction, elemental analysis, and cyclic voltammetry. 

Abstract Main‐group element‐mediated C−H activation remains experimentally challenging and the development of clear concepts and design principles has been limited by the increased reactivity of relevant complexes, especially for the heavier elements. Herein, we report that the stibenium ion [(^pyCDC)Sb][NTf₂]₃(1) (^pyCDC=bis‐pyridyl carbodicarbene; NTf₂=bis(trifluoromethanesulfonyl)imide) reacts with acetonitrile in the presence of the base 2,6‐di‐tert‐butylpyridine to enable C(sp³)−H bond breaking to generate the stiba‐methylene nitrile complex [(^pyCDC)Sb(CH₂CN)][NTf₂]₂(2). Kinetic analyses were performed to elucidate the rate dependence for all the substrates involved in the reaction. Computational studies suggest that C−H activation proceeds via a mechanism in which acetonitrile first coordinates to the Sb center through the nitrogen atom in a κ¹fashion, thereby weakening the C−H bond which can then be deprotonated by base in solution. Further, we show that1reacts with terminal alkynes in the presence of 2,6‐di‐tert‐butylpyridine to enable C(sp)−H bond breaking to form stiba‐alkynyl adducts of the type [(^pyCDC)Sb(CCR)][NTf₂]₂(3 a–f). Compound1shows excellent specificity for the activation of the terminal C(sp)−H bond even across alkynes with diverse functionality. The resulting stiba‐methylene nitrile and stiba‐alkynyl adducts react with elemental iodine (I₂) to produce iodoacetonitrile and iodoalkynes, while regenerating an Sb trication. 

Abstract The synthesis and characterization of (^tBuPBP)Ni(OAc) (5) by insertion of carbon dioxide into the Ni−C bond of (^tBuPBP)NiMe (1) is presented. An unexpected CO₂cleavage process involving the formation of new B−O and Ni−CO bonds leads to the generation of a butterfly‐structured tetra‐nickel cluster (^tBuPBOP)₂Ni₄(μ‐CO)₂(6). Mechanistic investigation of this reaction indicates a reductive scission of CO₂by O‐atom transfer to the boron atom via a cooperative nickel‐boron mechanism. The CO₂activation reaction produces a three‐coordinate (^tBuP₂BO)Ni‐acyl intermediate (A) that leads to a (^tBuP₂BO)−Ni^Icomplex (B) via a likely radical pathway. The Ni^Ispecies is trapped by treatment with the radical trap (2,2,6,6‐tetramethylpiperidin‐1‐yl)oxyl (TEMPO) to give (^tBuP₂BO)Ni^II(η²‐TEMPO) (7). Additionally,¹³C and¹H NMR spectroscopy analysis using¹³C‐enriched CO₂provides information about the species involved in the CO₂activation process. 

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures. Related Article: Fanji Kong, Diane A. Dickie, T. Brent Gunnoe|2022|CSD Communication|||