CONFORMATIONAL FLEXIBILITY OF THE DI(1,3-DIAMINOPROPANE)COPPER(II) CATION .2. STRUCTURE DETERMINATION FOR AQUA-DI(1,3-DIAMINOPROPANE-N,N')COPPER(II) DICHLORIDE AND CHLORODI(1,3-DIAMINOPROPANE-N,N')COPPER(II) CHLORIDE METHANOL SOLVATE AND DFT CALCULATIONS FOR AQUA-DI(1,3-DIAMINOPROPANE-N,N')COPPER(II) CATION

The structures of aqua-di(1,3-diaminopropane-N,N')copper(II) dichlorid e (1) and chloro-di(1,3-diaminopropane-N,N')copper(II) chloride methan ol solvate (2) were determined by single crystal X-ray methods. [Cu(tn )(2)H2O]Cl-2 (1) (tn=1,3-diaminopropane), C6H22Cl2CuN4O, M(r)=300.72, tetragonal, space group P4(2)nm (No. 102), a=9.3146(5), c=7.591(1) Ang strom, V=658.63(9) Angstrom(3), Z=2, D-c=1.516 g cm(-3). [Cu(tn)(2)Cl] Cl . MeOH (2), C7H24Cl2CuN4O, M(r)=314.74, monoclinic, space group P2( 1)/c (No. 14), a=8.598(2), b=16.176(2), c=10.418(4) Angstrom, beta=107 .11(3)degrees, V=1384.7(7) Angstrom(3), Z=4, D-c=1.510 g cm(-3). Compo und 1 is formed in aqueous solution, whereas 2 was obtained in methano l. The coordination polyhedron in 1 is square pyramid with exceptional ly high site symmetry of 4mm (C-4 nu) around the copper(II) cation. Th e distances from the central copper(II) cation to the two nearest chlo ride ions are different in 2, 2.736(2) and 3.322(2) Angstrom. If the r emote chloride is not taken into consideration, the coordination polyh edron could be described as distorted square pyramid. In both compound s the chelate rings display chair conformation. In 1 the two tn ligand s are coordinated to copper in syn-like fashion, whereas in 2 the ring s are in normal anti-like conformation. The rare syn-like conformation is a stable conformation, since the overall geometry was not changed during optimization carried out at the LDA/DNP level of theory. The op timized syn-like conformation is favoured by 16.38 kJ mol(-1) over the optimized anti-like conformation of the [Cu(tn)(2)(H2O)](2+) cation.