Caffeine in copper(II) complexes: crystal and molecular structure of di(caffeine) tetrakis(naproxenato) dicopper(II)

The crystal and molecular structure of di(caffeine)tetrakis(naproxenato)- d icopper(II) was determined by direct method and Fourier techniques. The str ucture was refined by full-matrix least-squares methods to a weighted R fac tor of 0.0705. The compound is binuclear with square pyramidal geometry at each copper(II) centre. The two copper(II) atoms are bridged by four carbox ylate groups, while the apical ligands are caffeine molecules. The Cu-Cu di stance is 2.649(2) Angstrom. The Cu atoms are displaced by 0.217 Angstrom f rom the plane containing four oxygen atoms bonded to Cu towards the apical caffeine molecules. The structural data are compared with those found in si milar [Cu-2(RCOO)(4)(caf)(2)] (caf = caffeine) complexes. (C) 2000 Elsevier Science S.A. All rights reserved.