Model compounds for galactose oxidase:: The crystal and molecular structure of dimeric (4-methylpyridine-N) (N-salicylidene-tyrosinato-O, N, O′)copper(II)

Galactose oxidase is a type II copper protein that contains a square-pyramidal five-coordinate copper center and catalyzes the oxidation of primary alcohols to aldehydes with a concomitant reduction of molecular oxygen. Dimeric (4-methylpyridine-N)(N-salicylidene-tyrosinato-O, N, O')copper(II), which contains two square-pyramidal five-coordinate copper centers and thus serves as a model for galactose oxidase, crystallizes in the monoclinic space group P2(1)/c with a = 8.914(1) Angstrom, b = 18.415(2) Angstrom, c = 12.802(2) Angstrom, beta = 107.70(1)degrees. The dinuclear unit comprises two four-coordinate units each consisting of the tridentate Schiff base and 4-methylpyridine with a weaker out-of-plane link to the phenolic oxygen atom from the adjoining unit in a typical 4 + 1 distorted square-pyramidal geometry.