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While the oxidative chemistry of transition metals such as iron and copper is a highly developed area of investigation, the study of similar chemistry with nickel is much younger. However, nickel offers rich coordination chemistry with oxygen and other oxidants and is a promising avenue of research for applications such as sustainable hydrocarbon functionalization. Herein, we summarize the progress made recently in nickel coordination chemistry relevant to hydrocarbon functionalization and offer our perspectives on open questions in the field. [ABSTRACT FROM AUTHOR]

Click reactions on poly[(methyl acrylate)‐co‐(5‐azido‐1‐pentene)], synthesized by radical polymerization of methyl acrylate and 1‐bromo‐5‐pentene, and converted into the click‐ready azido form by nucleophilic substitution with sodium azide, were studied. Propargyl benzoate and propargyl acetate were clicked onto the polymeric substrate, with the latter known to be a poor click reactant. The impact of solvents (dimethyl formamide (DMF) and tetrahydrofuran (THF)), catalytic systems (CuSO4/Na ascorbate, [Cu(BPMEN)(ClO4)2]/Na ascorbate, bromotris(triphenylphosphine) copper(I) ([CuBr(PPh3)3])) and the addition of chelating nitrogenous bases (triethylamine (TEA), diisopropylethylamine, N,N,N′,N″,N″‐pentamethyldiethylenetriamine) on the degree of conversion was analyzed. Only reactions catalyzed with [CuBr(PPh3)3] led to high or complete conversions in both solvents. Reactions catalyzed with the pre‐catalyst complexes CuSO4⋅5H2O and [(CuBPMEN)(ClO4)2], which require the in situ reduction of Cu(II) to Cu(I) by sodium ascorbate, yielded incomplete conversions in both solvents. Adding chelating nitrogenous bases, with TEA being the most effective, yielded complete conversions for propargyl benzoate with all three catalytic systems in DMF. Adding TEA to reactions of propargyl acetate in DMF increased conversion by 17.9% for CuSO4⋅5H2O/Na ascorbate and 29.6% for [(CuBPMEN)(ClO4)2]/Na ascorbate. The addition of chelating bases was more effective in DMF than in THF, which was also the less suited solvent in reactions without chelating bases. The results show that click reactions with propargyl reagents that cannot increase the nucleophilicity of the vinylidene‐like β‐carbon through electron conjugation yield lower conversions. The effectiveness of catalytic systems that undergo in situ reductions can be enhanced by nitrogenous chelating bases that stabilize the Cu(I) stage. © 2023 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

This paper describes the synthesis, and electronic and redox properties of three nickel(II) and two copper(II) complexes, namely, [Ni(L1)(Cl)2]·2H2O (1), [Ni(L2)(Cl)2]·H2O (2), [Cu(L2)(ClO4)]ClO4 (3), [Ni(L3)(Cl)2]·H2O (4), and [Cu(L3)(ClO4)]ClO4·2H2O (5). Ligands L1, L2 and L3 each contain a 1,2-bis((pyridine-2-ylmethyl)-azaneyl)ethane framework decorated with electron donating methyl and methyl/methoxy substituents. We observe a correlation between the electron donating capability of the ligands (L1 < L2 < L3) and the redox potential for the MII/MI couple (1 > 2 > 4 and 3 > 5). After thorough identification of the spectroscopic and redox properties of 1–5, the reactivity of the complexes was investigated towards proton and water reduction by means of electro and photocatalysis. These species seemingly support H2 evolution and display tunable catalytic properties achieved through the presence of differentiated electron donicity. Evidence of degradation with nanoparticle conversion was found to depend on the nature of both ancillary ligand and metal center. [ABSTRACT FROM AUTHOR]

This tutorial review illustrates opportunities for the resolution of structure-function relationships to aid in the development of new materials for solar energy conversion using a combination of spectroscopy and catalysis measurements with X-ray scattering analyses to provide in situ structural characterization of solar fuels catalysts. As an example, the use of molecular cobaloxime catalysts in bimolecular and supramolecular photocatalysis schemes for proton reduction is briefly reviewed. These highlight the need to develop new modular, hierarchical, self-healing supramolecular architectures for solar fuels catalysis. Examples of the X-ray scattering structural analysis of amorphous materials in the context of photocatalytic function are discussed in detail.