Cobalt-based molecular electrocatalysis of nitrile reduction: evolving sustainability beyond hydrogen.

Two new cobalt bis-iminopyridines, [Co(DDP)(H2O)2](NO3)2 (1, DDP = cis-[1,3-bis(2-pyridinylenamine)] cyclohexane) and [Co(cis-DDOP)(NO3)](NO3) (2, cis-DDOP = cis-3,5-bis[(2-Pyridinyleneamin]-trans-hydroxycyclohexane) electrocatalyse the 4-proton, 4-electron reduction of acetonitrile to ethylamine. For 1, this reduction occurs in preference to reduction of protons to H2. A coordinating hydroxyl proton relay in 2 reduces the yield of ethylamine and biases the catalytic system back towards H2.