Nickel complexes sulfur dioxide

Reduction of both nickel porphyrins and thiaporphyrins to Ni1 species has been studied by EPR and 2H NMR spectroscopy.179, 2 58 The Ni1 complex of 5,10,15,20-tetraphenyl-21-thiaporphyrin has been isolated and characterized. Reaction of this complex with sulfur dioxide produced a paramagnetic five-coordinated Ni1 S02 adduct, while reaction with nitrogenous base ligands (amines, pyridines, imidazoles) yielded five- and six-coordinate complexes. In addition, the crystal structure of Ni1 diphenyldi-p-tolyl-21-thiaporphyrin has been determined. The coordination geometry about the nickel center is essentially square planar with extremely short Ni—N and Ni—S bonds (Ni—N = 2.015(2) A, 2.014(12) A, and 1.910(14) A and Ni—S = 2.143(6) A).2359... 

Fig. 25. Ni(np3)(S02). (Reprinted, with permission, from Synthesis and Structural Characterization of a Sulfur Dioxide Complex of Nickel with Tris-(2-(d henylphosphino)ethyl)amine, Mealli, C. et al. Inorg. Chem. 17, 3021, Fig. 1, copyright, 1978, by the American Chemicd Society)...

The production of coke by the carbonization of bituminous coal leads to the release of chemically complex emissions from coke ovens that include both gases and particulate matter of varying chemical composition. The chemical and physical properties of coke oven emissions vary depending on the constituents. The emissions include coal tar pitch volatiles (e.g., particulate polycyclic organic matter, polycyclic aromatic hydrocarbons, and polynuclear aromatic hydrocarbons), aromatic compounds (e.g., benzene and jS-naphthyl amine), trace metals (e.g., arsenic, beryllium, cadmium, chromium, lead, and nickel), and gases (e.g., nitric oxides and sulfur dioxide). 

The Ni(0)-mediated coupling reaction could be successfully applied to Vitamin D derivatives. Nickel chloride is reduced with zinc powder in pyridine to nickel(O), and this forms a brick-red complex with the acrylate ester. This, in turn, is smoothly alkylated by the alkyl iodide. The reaction is widely appUcable it can also be carried out successfully with the sulfur dioxide adducts, and ethyl acrylate may be replaced by methyl vinyl ketone as well. 

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