Termocromismo em soluções de alcóxidos de Vanádio(IV): uma abordagem pela modelagem molecular Thermochromic behavior of vanadium(IV) alkoxides in solution: a molecular modeling aproach
| Autor: | Alexandre C. de Freitas, Kátia C. M. Westrup, Giovana G. Nunes, Denis J. Gulin, Roberto L. A. Haiduke, Jaísa F. Soares, Eduardo L. de Sá |
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| Jazyk: | English<br />Spanish; Castilian<br />Portuguese |
| Rok vydání: | 2010 |
| Předmět: | |
| Zdroj: | Química Nova, Vol 33, Iss 1, Pp 52-56 (2010) |
| Druh dokumentu: | article |
| ISSN: | 0100-4042 1678-7064 |
| DOI: | 10.1590/S0100-40422010000100011 |
| Popis: | The thermochromic behavior exhibited by vanadium(IV) alkoxides, [V2(μ-OPr i)2(OPr i) 6] and [V2(μ-ONep)2(ONep)6 ], OPr i = isopropoxide and ONep = neopentoxide, was studied by molecular modeling using DFT, TDDFT and INDO/S methods. The vibrational and electronic spectra calculated for [V2(μ-OPr i)2(OPr i) 6] were very similar to the experimental data registered for crystalline samples of the complex and for its solutions at low temperature (< 210 K), while spectra recorded at high temperature (> 315 K) were compatible with those calculated for the monomeric form, [V(OPr i)4]. These results consistently point to a monomer/dimer equilibrium as an explanation for the solution thermochromism of {V(OPr i)4}n. In spite of the structural similarity between [V2(μ-ONep)2(ONep)6 ] and [V2(μ-OPr i)2(OPr i) 6] in the solid state, the thermochromic behavior of the former could not be explained by the same model, and the possibility of tetranuclear aggregation at low temperatures was also investigated. |
| Databáze: | Directory of Open Access Journals |
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