SYN VERSUS ANTI CONFORMATION IN MONODENTATELY COORDINATED SULFONATE GROUPS - CRYSTAL-STRUCTURE DETERMINATION AND MMX FORCE-FIELD CALCULATIONS FOR NZENESULFONATO)BIS(1,3-DIAMINOPROPANE)-COPPER(II), C20H34CUN4O6S2

The structure of the title compound was determined by single-crystal X -ray methods. The compound crystallizes in the orthorhombic crystal sy stem (space group Pbca, No. 61) with a = 25.282(2), b = 11.318(2), c = 8.765(2) angstrom, V = 2508(1) angstrom3 and Z = 4. The Cu(II) ion li es at a centre of symmetry and displays elongated pseudo-octahedral st ereochemistry. The equatorial Cu-N distances are Cu-N1 = 2.036(5) and Cu-N2 = 2.021(5) angstrom. The axial 4-methylbenzenesulfonate ion is m onodentately coordinated to the Cu(II) ion, displaying an anti conform ation. The Cu-0 distance is 2.581(5) angstrom and the Cul-01-S1 angle is 129.6(2)-degrees. The chelate ring, consisting of a 1,3-diaminoprop ane ligand coordinated to the Cu(II) ion, has a chair conformation wit h puckering values close to those calculated using semiempirical MMX f orce-field calculations. The calculations also predict that the anti c onformation is the most stable coordination mode for the 4-methylbenze nesulfonate anion.