Reactions of Bis(β-Alaninato) Metal(II) Complexes with Formaldehyde and Benzamide: The Crystal Structure of Bis[N-Methyl-N-(N′-Methyl-Benzamido)-β-Alaninato]Copper(II) Monohydrate and Characterization of Bis[N,N-DI(N′-Methylbenzamido)-β-Alaninato]Metal(II) Complexes

Abstract

The bis[N-methyl-N-(N'-methylbenzamido)-β-alaninato]copper(II), Cu(II)[Me-MeBA]2, is synthesized by reacting bis(β-alaninato)copper(II) with formaldehyde and benzamide in the presence of a base (NaOH) over the pH range 5.5-8.5. However, the bis[N,N-di (N'-methylbenzamido)-β-alaninato]metal(II) complexes, M(II)[DMeBA]2 (M = Zn, Ni, Co), are obtained when the respective bis(β-alaninato)metal(II) reacts with formaldehyde and benzamide in the presence of the base in similar pH ranges. Nevertheless, Cu(II)[DMeBA]2 can be synthesized if the reaction is carried out in the absence of base. The M(II)[DMeBA]2 complexes are characterized by elemental analysis, IR and UV-Visible spectroscopy and magnetic susceptibility measurements. X-ray crystal structure analysis of Cu(II)[Me-MeBA]2 suggests that the N'-methylbenzamido substituent of the β-alanine moiety is formed through Mannich aminomethylation, and that the other N-methyl substituent is formed via a Canizzaro-type methylation.