Stereochemistry of Complexes With N -Alkylated Amino Acids. X. Crystal Structure and Molecular Mechanics Calculations for Bis(d,l-N,n -Dimethylvalinato)copper(ii)

The crystal structure of dark red, monoclinic (space group P21/c) bis(D,L-N,N-dimethylvalinato)-copper(II) was solved by X-ray diffraction methods and refined to R = 0.035. Coordination around copper(II) atom is irregular square-planar with oxygen and nitrogen atoms in trans positions [Cu-O = 1.911(2), Cu-N = 2.018(2)Å, O-Cu-N = 84.11(7), O-Cu-N′ = 95.89(7)°]. The structure of the molecule corresponds to the most stable conformation, as predicted by molecular mechanics calculations. MM calculations reproduced (as measured by root-mean-square deviations) the angles around copper(II) to 0.49° and interatomic distances in the molecule to 0.055 Å. The MM calculations in the crystal state suggest an influence of packing interactions on molecular conformation.