Synthesis, X-ray structure, and characterization of a complex containing the Hexakis(urea) cobalt(II) cation and lattice urea molecules

The 12 : 1 reaction of urea (U) with CoI2 in EtOH yielded the "clathrate-coordination" compound [CoU6] I-2 center dot 4U (1). The complex crystallizes in the monoclinic space group P2(1)/c. The lattice constants are a = 9.844(4), b = 7.268(3), c = 24.12(1) angstrom, and beta = 98.12(1)degrees. The crystal structure determination demonstrates the existence of octahedral [CoU6](2+) cations, I- counterions, and two different types (two U-1 and two U-2) of hydrogen- bonded, lattice urea molecules. The [CoU6](2+) cations and the U-1 lattice molecules form two- dimensional hydrogen- bonded layers which are parallel to the ab plane. The I- anions are placed above and below each layer, and are hydrogen bonded both to U1 molecules and [CoU6](2+) cations. Each U-2 molecule is connected to a [CoU6](2+) cation through an N-H center dot center dot center dot O hydrogen bond resulting in a three- dimensional network. Room temperature magnetic susceptibility and spectroscopic (solid-state UV/Vis, IR, Raman) data of 1 are discussed in terms of the nature of bonding and the known structure. Copyright (c) 2007 Labrini Drakopoulou et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.