N-acetyl-DL-tryptophanatometal(II) (Co(II), Ni(II) and Zn(II)) complexes and their amine adducts.

First row transition metal(II) complexes of N-acetyl-DL-tryptophan of the type M(Actrp)2·xH2O (M = Co(II), Zn(II) and x = 2; M = Ni(II) and x = 3; Actrp = N-acetyl-DL-tryptophanato ion) and their amine adducts of the type M(Actrp)2B2 (B = py, 3-pic and 4-pic) were prepared and investigated by means of magnetic measurements, electronic and infrared spectroscopy. The diamagnetic zinc(II) complexes were also investigated in solution by means of 1H n.m.r. spectroscopy. All the experimental results on solid complexes suggest that the carboxylate is coordinated to the metal atom. The effect of the amines in axial position results in a weakening of the strength of the amino acid in-plane coordination. 1H n.m.r. spectra of the diamagnetic zinc(II) complexes indicate that the same type of amino acid coordination also exists in solution.