HYDROGEN-BONDING IN BE[C2(COO)2] 4H2O-A NEUTRON-DIFFRACTION STUDY AT 15-K

Lattice constants for orthorhombic Be[C2(COO)2]·4H2O at 15 K are a=1006.4(6), b=663.0(4), and c=1263.1(7) pm, Z=4, space group Cmcm. Anisotropic refinement on single crystal neutron diffraction data led to Rw=0.0229. The crystal structure is made up by slightly distorted Be(H2O)2+/4 tetrahedra (Be-H2O 161. 3 and 162.0 pm) and planar [C2(COO)2]2- anions linked together by strong (O... H2O 262.0 and 263.5 pm) asymmetric hydrogen bonds. A layer-like arrangement extending parallel to (010) consisting of [C2(COO)2]2- anions and hydrogen bound water molecules of the Be(H2O2+/4 tetrahedra is the primary structural feature of Be[C2(COO)2]·4H2O. These layers are stacked in ... ABAB... sequence and interlinked by coordinative bonds between Be2- and H2O to yield a rigid three-dimensional framework. O-H bond length corrected for thermal motion are 100.4 and 100.5 pm, respectively. The H-O-H angle are rather wide (111.12 and 114.36°). The anion has mmm symmetry. © 1992 Academic Press, Inc.