On the mechanism of reduction of maleate and fumarate by NiI(1,4,8,11-tetraazacyclotetradecane)+ in aqueous solutions

Abstract

Ni(I)(1,4,8,11-tetraazacyclotetradecane)(+), Ni(I)L(+), was produced in neutral aqueous solutions by radiolytic techniques. The mechanism and kinetics of the reaction of Ni(I)L(+) with maleate and fumarate were studied applying pulse-radiolysis and analysis of the final products. Surprisingly the mechanisms of reduction of maleate and fumarate differ considerably. Based on the results it was also shown that Ni(II)L(2+) is an electrocatalyst for the reduction of alkenes in aqueous solutions.

On the mechanism of reduction of maleate by a Co(I) complex with a macrocylic ligand in aqueous solutions

“…The mechanism observed in the CoL-maleate systems is similar to that observed in the NiL 2 system [34] in that initially maleate forms a -complex with the central metal cation. It differs from that observed for the NiL 2 system in that the yield of succinate is y = 1270x -3000 considerably lower in the cobalt system.…”

“…CO À 2 , on the mechanism of reduction of alkenes by Ni(I)L þ yielded the following results [34]. The mechanisms of reduction of maleate and fumarate by [Ni(I)L 1 ] þ differ significantly from each other in spite of the similarity of the two substrates.…”

Electrocatalytic H2 Evolution by Proton-Gated Hangman Iron Porphyrins

“…Future studies will use recently reported methods to determine the mechanism of proton reduction on iron porphyrins and exploit our ability to modulate the effective rate of proton transfer to the catalyst’s active site. For instance, in cases where H 2 evolution represents a parasitic side reaction, such as carbon dioxide reduction, , nitrite reduction, − and olefin reduction in the acidic solutions, we wish to tailor the rate of proton transfer to the catalyst active site in order to minimize parasitic evolution of H 2 .…”

Developing electrochemical hydrogenation towards industrial application

“…Similar reactivity under reductive conditions was also reported for other alkenes earlier always accompanied by dimerization. [287][288][289][290] In combination with molecular nickel phosphine hydrogenation catalysts, 4 mediates the hydrogenation of alkynes and enones. 291 The application of the simple complex Ni(bpy) 3 2+ 5 (bpy = 2,2 0 -bipyridine) enabled the semihydrogenation of alkynes via molecular electrosynthesis.…”

“…Similar reactivity under reductive conditions was also reported for other alkenes earlier always accompanied by dimerization. 287–290 In combination with molecular nickel phosphine hydrogenation catalysts, 4 mediates the hydrogenation of alkynes and enones. 291…”