Reduction of nitrile to primary amine using sodium borohydride: Synthesis and protonation of a cis-octahedral macrocyclic nickel(II) complex bearing two 2-aminoethyl pendant arms

A cis-octahedral complex [NiL2]2+ bearing two coordinated N-CH2CH2NH2 pendant arms was prepared by a reaction of N-CH2CN groups attached to the L1 of [Ni(L1)(CH3COO)]+ with NaBH4. In acidic aqueous solutions, only one N-CH2CH2NH2 group of [NiL2]2+ was protonated selectively to yield [Ni(HL2)]3+, which is inert to protonation.50