Electrochemical monitoring of the oxidative coupling of alkynes catalyzed by triphenylphosphine gold complexes

Abstract

Abstract. Electrochemical monitoring of the oxidative coupling of alkynes in the homogeneous phase through catalytic cycles involving triphenylphosphine gold complexes and selectfluor as oxidant reveals that at least two gold species in +3 and +1 oxidation states are implicated. Electrochemically driven homocoupling of terminal alkynes using molecular oxygen as the oxidant can be performed using such catalysts.

Self-Assembly of Catalytically Active Supramolecular Coordination Compounds within Metal–Organic Frameworks

“…Conventional solution-phase voltammetry was performed as previously described for studying homocoupling reaction. 17 The voltammetric and catalytic activity of the studied SCCs@MOFs was analyzed using microparticulate deposits of such compounds on glassy carbon electrode. Such deposits were prepared by evaporation on the electrode surface of a drop (50 L) of a suspension (1 mg/mL) of the solid in ethanol.…”

“…This synthetic approach inherently induces the formation of SCCs with isolated fully-coordinated metal atoms as structural nodes, which hampers any activation of external reagents on the metal sites without destroying the assembly, thus severely limiting their use in metal-based Supramolecular Catalysis. This is exemplified by the few reactions reported with the archetypal roughly spherical polyhedra of general formula PdnL2n, in catalytic amounts, [14][15][16][17] as well as by the need to build up ensembles with already known catalytically-active metalloligands as linkers. [18][19][20] Thus, a new avenue of research may be opened by finding ways to exploit the metal-catalysis of the pivotal metal atoms building the SCCs.…”

Unique distal size selectivity with a digold catalyst during alkyne homocoupling

“…The results were nearly identical, with the same amounts of homocoupling products 2a (495%) or 2b (45%) obtained, and free alkyne 1-dodecyne 1b (B50%) released into solution for the case of the dodecynyl acetylide 6b. Cyclic voltammetry (Supplementary Figs 6 and 7 and Supplementary Discussion) confirmed that, in all the complexes tested, oxidation of Au(I) to Au(III) occurs without detecting any Au(II) species 9,16,23,28 . These results validate the mixed-valence digold intermediate Int-1 and clearly show that aurophilic bonding improves the reaction rate but that it is not involved in the distal size selectivity.…”

The Homocoupling Reaction of Aromatic Terminal Alkynes by a Highly Active Palladium(II)/AgNO3 Cocatalyst in Aqueous Media Under Aerobic Conditions

“…Palladium complexes in combination with Cu salts are traditionally employed as cocatalysts for the reaction [11,12,13,14,15,16,17,18]. Recently, apart from copper salts, catalysts, based on other transition metals such as Ni [19], Co [20], Au [21], and Ti [22] have also been employed in terminal alkyne homocoupling reactions. Moreover, an iron in combination with a Cu salt cocatalyst has also been reported [23].…”