The reaction of a nickel(i) carbonyl species with CH3I revealed the formation of (PNP)NiCOCH3 which differs from its zerovalent congener.

Reactions of nickel complexes supported by an anionic PNP pincer ligand (PNP − = N[2-P i Pr 2 -4-Me-C 6 H 3 ] 2 ) toward CO 2 and CO are investigated, particularly for interrogating their C−O bond formation/cleavage chemistry.The formation of a nickel formate species (2) was accomplished by the reaction of (PNP)NiH with CO 2 , while the structural isomer complex (PNP)NiCOOH-κC (4) was successfully produced from the corresponding nickel hydroxyl compound by exposing it to CO(g). Its structurally unique character was gleaned by obtaining two solid-state structures for (PNP)NiCOOH-κC (4) and {(PNP)Ni} 2 -μ-CO 2 -κ 2 C,O (6); the latter was obtained from the reaction of 4 with a nickel hydroxyl complex. Both species possess a NiCOO-κC binding mode, which is reminiscent of the binding mode found at the carbon monoxide dehydrogenase (CODH) active site with its Ni−COO− Fe fragment. The cationic species {(PNP)NiCO} + (7) was also prepared via the protonation of 4, which then led to the investigation of the C−O bond formation in 7 by adding a nucleophile such as OH − .

Annulated BODIPY chalcogenide (Se, Te) systems were synthesized from their respective bis(o-formylphenyl)dichalcogenide intermediates. The annulated BODIPY selenide product was confirmed by X-ray diffraction. The red-shifted telluride version was found to be sensitive and selective for hypochlorite detection, reversible upon treatment with biothiols.

To explore the reactivity of copper-alkylperoxo species enabled by the heterolytic peroxide activation, room-temperature stable mononuclear nonheme copper­(II)–alkylperoxo complexes bearing a N-(2-ethoxyethanol)-bis(2-picolyl)­amine ligand (HN3O2), [CuII(OOR)­(HN3O2)]+ (R = cumyl or t Bu), were synthesized and spectroscopically characterized. A combined experimental and computational investigation on the reactivity and reaction mechanisms in the phosphorus oxidation, C–H bond activation, and aldehyde deformylation reactions by the copper­(II)–alkylperoxo complexes has been conducted. DFT-optimized structures suggested that a hydrogen bonding interaction exists between the ethoxyethanol backbone of the HN3O2 ligand and either the proximal or distal oxygen atom of the alkylperoxide moiety, and this interaction consequently results in the enhanced stability of the copper­(II)–alkylperoxo species. In the phosphorus oxidation reaction, both experimental and computational results indicated that a phosphine-triggered heterolytic O–O bond cleavage occurred to yield phosphine oxide and alcohol products. DFT calculations suggested that (i) the H-bonding between the ethoxyethanol backbone and distal oxygen of the alkylperoxide moiety and (ii) the phosphine binding to the proximal oxygen of the alkylperoxide moiety engendered the heterolytic peroxide activation. In the C–H bond activation reactions, temperature-dependent reactivity of the copper­(II)–alkylperoxo complexes was observed, and a relatively strong activation energy of 95 kcal mol–1 was required to promote the homolytic peroxide activation. A rate-limiting hydrogen atom abstraction reaction of xanthene by the putative copper­(II)-oxyl radical resulted in the formation of the dimeric copper product and the substrate radical that further underwent autocatalytic oxidation reactions to form an oxygen incorporated product. Finally, amphoteric reactivity of copper­(II)–alkylperoxo complexes has been assessed by conducting kinetic studies and product analysis of the aldehyde deformylation reaction.