The Jahn-Teller effect in solutions of flexible molecules: a neutron diffraction study on the structure of a Cu 2+ solution in ethylene glycol
1995; Taylor & Francis; Volume: 85; Issue: 5 Linguagem: Inglês
10.1080/00268979500101601
ISSN1362-3028
Autores Tópico(s)Chemical and Physical Properties in Aqueous Solutions
ResumoAbstract The method of isotopic substitution in time-of-flight neutron diffraction is used to measure the coordination environment of Cu2+ in a 2·180(2) molal solution of Cu(CF3SO3)2 in fully deuterated ethylene glycol (EG). The results show that EG acts as a bidentate ligand to form [Cu(EG)3]2+ tris-chelate complexes. There is strong evidence for Jahn-Teller distortion of the complex which is best represented by a model wherein the octahedron is tetragonally elongated to give a (4 + 2) configuration with 4 oxygen atoms at 1·98 Å and 2 oxygen atoms at 2·26 Å. The cation correlations display intermediate range ordering, having a correlation length of approximately 32 Å, which can be interpreted in terms of an arrangement of the Cu2+ complexes which maximizes their mean separation. A new analysis is made for the results obtained from previous neutron diffraction experiments on a 2·00 molal solution of Cu(ClO4)2 in D2O and a 1·00 molal solution of Cu(NO3)2 in D2O. The [Cu(D2O)6]2+ complex in both solutions comprises a (4 + 2) structural configuration for which the degree of distortion is larger than indicated by the majority of X-ray diffraction and extended X-ray absorption fine structure measurements.
Referência(s)