Template synthesis of N2S and N3S chelates via alkylation of bis(2-aminoethanethiolato)Ni: sulfur- and nitrogen-centered alkylations

Alkylation of bis(2-aminoethanethiolato)nickel(II) (1) with alkylating agents containing pendant donor groups has been investigated. Reaction with 2-bromoethylamine is strictly sulfur-centered yielding (2-(2-aminoethyl)thio]ethaneamine)nickel(II)bromide, (DAES)₂Ni]Br₂ (2), which was isolated as a lilac solid. Addition of chloroacetamide yields the sulfur- and nitrogen-alkylated product (2-(2-aminoethyl)thio]acetamide)nickel(II)chloride, (AETA)NiCl₂ (3a), as a green solid. Recrystallization from water/acetone yields 3a as single crystals along with single crystals of (AETA)NiCl(OH₂)]Cl (3b). The strictly S-alkylated product (2-(2-amino-2-oxoethyl)thio]acetamide)nickel(II)iodide, (AOTA)₂Ni]I₂ (4), is obtained upon reaction of 1 with iodoacetamide. A pathway is proposed consistent with the observed leaving group effect on the site of alkylation. The X-ray structures of 3a, 3b, and 4 are reported and the hydrogen-bonding network is described.