Ns. Begum et H. Manohar, SYNTHESIS AND X-RAY CRYSTAL-STRUCTURE OF A CU-II-THEOPHYLLINE COMPLEX- [CU(THEO)(2) (H2O)(3)]CENTER-DOT-2H(2)O, Polyhedron, 13(2), 1994, pp. 307-312
The complex [Cu-II (theo)(2)(H2O)(3)].2H(2)O (theo = theophylline) was
obtained from aqueous solution. The crystals belong to the monoclinic
system, space group P2(1)/n, and are reflection twins about the (001)
face. The structure was solved using data from a twinned crystal and
refined to final R and R(W) values of 0.069 and 0.064, respectively. C
opper has a square-pyramidal coordination with two thee molecules coor
dinating through N(7) at equatorial positions. The remaining sites are
occupied by water molecules. O(6) of one of the thee molecules is at
the other axial site at a longer distance of 3.18 Angstrom. This could
lead to an alternate (4+1+1) octahedral coordination geometry for Cu-
II. The packing is stabilized by stacking interactions between the the
ophylline moieties at an average separation of 3.46 Angstrom.