CRYSTAL-STRUCTURE AND MOLECULAR-STRUCTURE OF O)BIS(1,3-DIAMINO-2-HYDROXYPROPANE-N,N')COPPER(II) AT 193-K AND 296-K

The structure of the title compound was determined by single-crystal X -ray methods. -O)bis(1,3-diamino-2-hydroxypropane-N,N)copper(II) cryst allises in the monoclinic crystal system, space group P2(1)/c, no. 14, Z = 2. At 193 K a = 6.507(9), b = 7.182(7), c = 24.300(8) Angstrom, b eta = 95.02(7)degrees and V = 1131(2) Angstrom(3); at 296 K a = 6.519( 2), b = 7.205(2), c = 24.445(5) Angstrom, beta = 95.12(2)degrees and V = 1144(1) Angstrom(3). The copper(II) displays elongated pseudo-octah edral coordination polyhedron with the site symmetry Ci. The 1,3-diami no-2-hydroxypropane forms a six-membered chelate ring displaying a cha ir conformation in the equatorial direction. The non-coordinated hydro xyl group in the chelate ring forms a hydrogen bond to a neighbouring coordinated oxygen atom of the carboxylate group. The axially situated carboxylate group is twisted about 82 degrees with respect to the ana logous compound, where the equatorial ligand is 1,3-diaminopropane wit hout a hydroxyl group. The non-coordinated oxygen is now projected in between the two chelate rings. The only significant difference upon co oling is seen in the compression of the axial Cu-O bond length from 2. 479(3) to 2.459(2) Angstrom. Based upon EHMO calculations, the amount of d-s mixing as a rationale for the axial elongation is about 6%.