Crystal and molecular structure of di-μ-phenoxido-bis-[N-{(2-hydroxybenzyl)-(S)-alaninato-κ3-O,O′,N}copper(II)].: A simple homodimetallic model for N-terminal tyrosine coordination with (S)-alanine as a second amino acid residue

Single-crystal X-ray diffraction study established the dimeric [Cu-2(ohb-(S)-Aln)(2)] structure (ohb-(S)-Ala = N-(2-hydroxylbenzyl-(S)-alaninate). The complex crystallizes in the tetragonal space group P4(3)2(1)2 with a = b = 8.849(1) Angstrom, c = 24.913(2) Angstrom, V = 1950.8(3) Angstrom(3), Z = 8. The Cu(II) ion has distorted square-pyramidal geometry with the equatorial positions occupied by three oxygen and one nitrogen atom. Each copper atom is weakly coordinated at the apical position by carbonyl oxygen atom of the neighbouring molecule at the distance 2.329(2) Angstrom. The Cu-Cu separation 3.0204(7) Angstrom and the Cu-O3-Cu angle 100.8(1)degrees lend to antiferromagnetic coupling (at room temperature mu(eff) = 1.35 mu(B)). The O1-Cu-O3 angle (151.9(1)degrees) indicates distortion of the square pyramid toward a trigonal bipyramid (tau = 0.23).