Kinetics of substitution of cis-bis(malonato)diaquochromate(III) with glycine, DL-alanine and DL-phenylalanine

The kinetics of interaction between amino acids such as glycine, DL-alanine and DL-phenylalanine and cis-bis(malonato)diaquochromate(III) has been studied spectrophotometrically as a function of [glycine], [DL-alanine] and [DL-phenylalanine]. The effect of pH, temperature and substrate is also studied. The substrate exists predominantly as the diaquospecies and amino acids (glycine, DL-alanine and DL-phenylalanine) as the zwitterion at the experimental conditions. The substitution reaction has been found to proceed via two steps: amino acid dependent and amino acid independent paths indicating that the substitution reaction occurs through associative interchange (Ia) mechanism in the amino acid dependent path and the dissociative mechanism in the independent path, showing the higher reactivity of single ended malonate complex.