Al(OH)_4-、Al(OH)_5^<2->、Al(OH)_6^<3->クラスターの非経験的^<27>Al NMR化学シフト計算

概要

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The effect of coordination number on ^<27>Al NMR chemical shift was studied using ab initio molecular orbital calculation. In order to mimic Al of four-, five- and six-coordinations Al, the clusters of Al (OH) 4_^-, Al (OH)_ 5^<2-> and Al (OH) _6^<3-> were employed for the calculation. The obtained shifts for Al (OH) _4^- , Al (OH) _5^<2-> and Al (OH)_ 6^<3-> were + 70.3, + 31.5 and -3.9 ppm, respectively, and were in reasonable agreement with observed shifts of Al-containing oxides. Present calculation supports the assignment of +30 ppm peak observed in aluminosilicate glasses as five-coordination state. Ab initio molecular orbital calculation can be used to establish the correlation between local structure and NMR chemical shift of Al-containing materials.
社団法人日本セラミックス協会の論文
1997-01-01