A tetra-nuclear copper(II) complex stabilizes an extended structure of a water nonamer:: Synthesis and characterization of [Cu4(C54H46N4O14)(OH)2] • 10H2O

A tetra-nuclear copper(II) complex [Cu-4(C54H46N4O14)(OH)(2)] center dot 10H(2)O (1) has been synthesized starting from L-tyrosine, NaOH, 2,6diformyl-4-methylphenol (dfp) and CUSO4 center dot 5H(2)O. Compound 1 crystallizes from an ethanol-water mixture in triclinic P (l) over bar space group. In the crystal of 1, two binuclear copper units, related by a center of symmetry, are bridged by two hydroxo bridges and results in the formation of a tetra-nuclear {Cu-4} structure. Five lattice water molecules, located in the asymmetric unit, interact among themselves and form an unusual form of a water nonamer. In the crystal, the water nonamer is again hydrogen bonded to the next nonamer forming a chainlike polymer. Each {Cu-4} complex unit attaches four such water nonamer chains. Variable temperature magnetic data fit to the Bleaney-Bower's equation with a Curie type of impurity of S = 0.5. The best fit of the magnetic data to this equation yielded 2J = -217, g = 2.019 and a TIP value of 60 x 10(-6) cm(3) mol(-1). (c) 2006 Elsevier Ltd. All rights reserved.