Electrocarboxylation of chloroacetonitrile mediated by a Ni(I) terpyridine complex: Voltammetric and spectroscopic studies

Photocatalytic 2‐Iodoethanol Coupling to Produce 1,4‐Butanediol Mediated by TiO2 and a Catalytic Nickel Complex

“…When terpyridine is co‐present, the SWV of Ni 2+ shows three reduction waves at the investigated potential range. The first reduction wave is a background signal (Figure S5), derived from the solvent (MeCN+MeOH); the other two reduction waves at −1.64 and −1.91 V are ligand‐based one‐electron reduction of [Ni(terpy) 2 ] 2+ [21] . This distinct reduction behaviour rationalises the chemical stability of [Ni(terpy) 2 ] 2+ against reduction to Ni clusters.…”

“…Therefore, the stabilization of Ni 2+ to inhibit precipitation on semiconductors is the premise for IEO coupling to produce BDO. Coordination with ligand has been used to inhibit metal ion deposition into nanoparticles, thanks to the favourable thermodynamics reflected in reduction potential [21] . Here we used terpyridine to stabilize Ni 2+ , also expecting to construct a steric chemical environment around Ni 2+ for selective coupling of β HE radical.…”

“…Apart from the first background signal, [Ni(terpy) 2 ] 2+ all show two reduction waves lower than −2.0 V (versus Fc + /Fc), and the reduction potential increases with terpyridine content (Figure 3b). Both the reduction waves have been studied to be ligand‐based reduction, [23] the first reduction product could be described as [Ni II (terpy)(terpy⋅ − )] + , which can be converted to [Ni I (terpy)Cl] with the removal of a terpyridine ligand [21, 24] . Therefore, when terpyridine is much less than Ni 2+ , such as 0.5 equivalents, the first reduction wave consists of the reduction of [Ni(terpy) 2 ] 2+ to [Ni II (terpy)(terpy⋅ − )] + and [Ni I (terpy)Cl].…”

“…Apart from this reduction process, [Ni II (terpy⋅ − ) 2 ] may also lose one terpyridine ligand, with the electron transfer to Ni II to afford [Ni I (terpy⋅ − )Cl] − . [Ni I (terpy)Cl] can also be reduced to a ligand‐based reduction product, with a reduction potential also in this range [21] . The above three reduction processes consequently constitute the third reduction wave with varied reduction potential.…”

“…Coordination with ligand has been used to inhibit metal ion deposition into nanoparticles, thanks to the favourable thermodynamics reflected in reduction potential. [21] Here we used terpyridine to stabilize Ni 2 + , also expecting to construct a steric chemical environment around Ni 2 + for selective coupling of βHE radical. We prepared the terpyridine-coordinated Ni 2 + .…”