Chemical reactivity of hypervalent silicon compounds: The local hard and soft acids and bases principle viewpoint |
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Affiliation: | (1) Departamento de Química, División de Ciencias Básicas e Ingeniería, Universidad Autónoma Metropolitana-Iztapalapa, A.P. 55-534, 09340 México, D.F., México |
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Abstract: | The silicon atom may increase its coordination number to values greater than four, to form pentacoordinated compounds. It has been observed experimentally that, in general, pentacoordinated compounds show greater reactivity than tetracoordinated compounds. In this work, density functional theory is used to calculate the global softness and the condensed softness of the silicon atom for SiH n F4−n and SiH n F 5−n 1− . The values obtained show that the global and condensed softness are greater in the pentacoordinated compounds than in the tetracoordinated compounds, a result that explains the enhanced reactivity. If the results are analysed through a local version of the hard and soft acids and bases principle, it is possible to suggest that in nucleophilic substitution reactions, soft nucleophiles preferably react with SiH n F 5−n 1− , and hard nucleophiles with SiH n F4−n . |
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Keywords: | Density functional theory hard and soft acid and bases principle hypervalent silicon compounds |
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