The crystal structure of (L-proline-L-alanine) copper (II)·2·5 H2O

The crystal and molecular structure of (L-proline-L-alanine) Cu·2·5 H2O has been determined by the heavy atom method with 583 visually estimated reflexions and refined by full matrix least squares toR=0·101. The crystals are monoclinic witha=16·47 (3),b=7·74 (2),c=9·51 (3) Å andβ=109·7 (5)°; space groupC2;Z=4. The copper coordination is nearly square pyramidal with one water in the basal plane and another occupying the apical together with the aminoN, peptideN and the carboxylO of the dipeptide in the coordination. The Cu-peptide-Cu linkage isvia the hydrogen bonding between the water in the basal plane and the carbonyl O atom of the proline residue. One water is on the 2-fold axis.