Crystal structure of the clathrate compound [dibromotetra(pyridine)copper(II)]·pyridine. Characterization by EXAFS of the pyridine desorption product
Tóm tắt
Powder samples of the new compound [Cu(C5H5N)4·Br2](C5H5N) and of its desorption product have been studied by EXAFS. The crystal structure of [Cu(C5H5N)4Br2]·(C5H5N) has been determined from three-dimensional X-ray diffraction data and refined to theR value 0.038 for 379 observed reflections. (orthorhombic,Ccca,a=12.033(8),b=14.764(3),c=16.768 Å,V=1897(3) Å3,Z=4). The copper atom lies on a 222 symmetry site and is hexacoordinated with four nitrogen and two bromine atoms, forming an elongated octahedron with the bromine atoms in apical positions (Cu−Br distance: 3.201(2) Å, Cu−N1/N2 distances: 2.02(1)/2,07(1) Å). The host molecules (Cu(C5H5N)4Br2) form layers parallel to the (001) plane. Cavities in the space between these layers, bound by pyridine ligands protruding into this space, are occupied by the guest molecules (C5H5N). The guest desorption at room temperature is accompanied by a chemical and structural destruction of the host, leading to the known compound Cu(C5H5N)2Br2.
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