Various unsymmetrical aryl sulfides were synthesized by nickel-catalyzed C–S bond formation in good to excellent yields. The reactions employed arylsulfonyl chlorides as an aryl thiol source and Mn dust as a reducing agent. The scope and versatility of the method have been successfully demonstrated with 42 examples. Mechanistic studies revealed the existence of an intermediate disulfide substance. A catalytic cycle was proposed including a three-step reduction by Mn for the achievement of the reaction, and Ni(0) and Ni(I) species were supposed to be involved in the reaction mechanism.

A di-(2-pyridylmethyl)phenylamine ((PyCH2)2NPh) supported Cu(II)/O2 catalytic system was explored with the synthesis of pyridylmethyl-based compounds of carboxylate (PyCOOH), amide (PyC(O)NHPh), and imine (PyCHNPh) from the oxidative N-dealkylation of N-(2-pyridylmethyl)phenylamine (PyCH2NHPh) and its derivatives, by means of controlling the addition of a base and/or water to the reaction system under a dioxygen atmosphere at room temperature. Experimental studies showed that the imine and amide species could be precursors in succession in the way to the final oxidation state of carboxylates. A cyclic catalytic mechanism was proposed including the base triggered C–H bond activation of the 2-pyridylmethyl group (PyCH2–) and the intermolecular Cu–OOH α-hydrogen atom abstraction from the coordinated imine substrate (PyCHNPh).

•Synthesis of a tetranuclear carbonate-bridged Cu(II) through oxidation of Cu(I) by controlling concentration of O2 in CO2.•Lower concentration of O2 generated the target product, but higher would give product as a bis-μ2-hydroxo Cu(II) complex.•Nucleophilic attack of μ-peroxo Cu(II) species to CO2 molecules was proposed as the key step to form the desired product.A dimeric tetranuclear carbonate-bridged Cu(II) complex [Cu4(DPA-iBu)4(μ2-CO3)2(MeOH)2]4 +1 was prepared in-situ through oxidation of Cu(I) species by controlling the concentration of O2 in CO2. Lower concentration of O2 led to the formation of 1 after CO2 fixation but higher would give product as bis-μ2-hydroxo complex [Cu(DPA-iBu)(OH)]22 +2, which was found to be an intermediate to generate trinuclear carbonated complex [Cu3(DPA-iBu)3(μ3-CO3)(MeCN)2(H2O)]4 +3. The mechanism of this reaction was proposed and the nucleophilic attack of μ-peroxo Cu(II) species to CO2 molecules was suggested to be responsible for the generation of 1.A dimeric tetranuclear carbonate-bridged Cu(II) complex [Cu4(DPA-iBu)4(μ2-CO3)2(MeOH)2]4 +1 was prepared in-situ through oxidation of Cu(I) species by controlling the concentration of O2 in CO2.

Various unsymmetrical aryl sulfides were synthesized by nickel-catalyzed C–S bond formation in good to excellent yields. The reactions employed arylsulfonyl chlorides as an aryl thiol source and Mn dust as a reducing agent. The scope and versatility of the method have been successfully demonstrated with 42 examples. Mechanistic studies revealed the existence of an intermediate disulfide substance. A catalytic cycle was proposed including a three-step reduction by Mn for the achievement of the reaction, and Ni(0) and Ni(I) species were supposed to be involved in the reaction mechanism.