Stereochemistry of Complexes with N-Alkylated Amino Acids. VI. Crystal Structure of BIS(N-Tert-Butyl-N-Methylglycinato)Aquacopper(II). Conformational Analysis and Molecular Mechanics Calculations

The structure of blue, orthorhombic crystals of bis(N-tert-butyl-N-glycinato)aquacopper(II) was solved by X-ray diffraction method and refined to R = 0.026. The copper atom has a distorted square-pyramidal coordination with two nitrogen atoms and two oxygen atoms in trans positions in the equatorial plane and an apically coordinated water molecule. The structure is built up of discrete molecules linked together via C=O...H-OH hydrogen bridges. The Cu-O [1.922 (2)Å], Cu-N [2.081 Å(2)] and Cu-OW [2.464 (2)Å] distances are comparable with those of copper(II) complexes with other α-amino acids. The conformation of the molecule corresponds to the most stable conformer predicted theoretically.