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

Abstract

The 12 : 1 reaction of urea (U) with CoI2 in EtOH yielded the "clathrate-coordination" compound [ CoU 6 ]I2 ·4U (1). The complex crystallizes in the monoclinic space group P21/c. The lattice constants are a = 9.844(4), b = 7.268(3), c = 24.12(1) , and β=98.12 (1) ° . The crystal structure determination demonstrates the existence of octahedral [ CoU 6 ] 2+ cations, I- counterions, and two different types (two U1 and two U2) of hydrogen-bonded, lattice urea molecules. The [ CoU 6 ] 2+ cations and the U1 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 [ CoU 6 ] 2+ cations. Each U2 molecule is connected to a [ CoU 6 ] 2+ cation through an NH⋯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.