A DFT Quantum-Chemical Study on the Structures and Active Sites of Polymethylaluminoxane Научная публикация
| Журнал |
Macromolecular Theory and Simulations
ISSN: 1022-1344 , E-ISSN: 1521-3919 |
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| Вых. Данные | Год: 1999, Том: 8, Номер: 3, Страницы: 272-278 Страниц : 7 DOI: 10.1002/(SICI)1521-3919(19990501)8:3<272::AID-MATS272>3.0.CO;2-E | ||
| Ключевые слова | OLEFIN POLYMERIZATION CATALYSTS; ETHYLENE POLYMERIZATION; METHYL ALUMINOXANE; COMPLEXES; EQUILIBRIA; SYSTEMS | ||
| Авторы |
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| Организации |
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Информация о финансировании (1)
| 1 | Российский фонд фундаментальных исследований | 98-03-33132 |
Реферат:
The electronic structure and geometry of polymethylaluminoxane (MAO) [—Al(CH3)O—]n with different size (n = 4–12) have been studied using quantum-chemical DFT (density functional theory) calculations. It has been found: 1) Starting from n = 6, the three-dimensional oxo-bridged (cage) structure of MAO is more stable than the cyclic structure. 2) Both for cage structure and for cyclic structure the Lewis acidity of Al atoms characterized by their net positive charge amplifies with increasing size of MAO (n). 3) Trimethylaluminium (AlMe3) reacts with the cage structure of MAO with cleavage of an Al-O dative bond and formation of acidic tri-coordinated Alv and basic di-coordinated Ov atoms in the MAO molecule. Two molecules AlMe3 are associated with acidic Alv and basic Ov centers. As the MAO increases in size, the acidity of Alv centers amplifies and the distance Alv-(AlMe3) shortens; on the contrary, interaction of AlMe3 with Ov centers weakens and the distance Ov-(AlMe3) increases with increasing n value. The total heat of Al2Me6 interaction with MAO (sum interaction of Alv-(AlMe3) and Ov-(AlMe3)) noticeably decreases as the size of MAO increases (from 50.9 kcal/mol for n = 4 to 20.2 kcal/mol for n = 12). It is proposed that acidic Alv and basic Ov centers formed in the cage structure of MAO interact with zirconocene yielding ‘cation-like’ zirconium active centers.
Библиографическая ссылка:
Zakharov I.I.
, Zakharov V.A.
, Potapov A.G.
, Zhidomirov G.M.
A DFT Quantum-Chemical Study on the Structures and Active Sites of Polymethylaluminoxane
Macromolecular Theory and Simulations. 1999. V.8. N3. P.272-278. DOI: 10.1002/(SICI)1521-3919(19990501)8:3<272::AID-MATS272>3.0.CO;2-E WOS Scopus РИНЦ CAPlusCA OpenAlex
A DFT Quantum-Chemical Study on the Structures and Active Sites of Polymethylaluminoxane
Macromolecular Theory and Simulations. 1999. V.8. N3. P.272-278. DOI: 10.1002/(SICI)1521-3919(19990501)8:3<272::AID-MATS272>3.0.CO;2-E WOS Scopus РИНЦ CAPlusCA OpenAlex
Даты:
| Поступила в редакцию: | 26 июл. 1998 г. |
| Принята к публикации: | 25 нояб. 1998 г. |
| Опубликована online: | 21 апр. 1999 г. |
| Опубликована в печати: | 1 мая 1999 г. |
Идентификаторы БД:
| Web of science: | WOS:000080179500011 |
| Scopus: | 2-s2.0-22644450963 |
| РИНЦ: | 13309286 |
| Chemical Abstracts: | 1999:304284 |
| Chemical Abstracts (print): | 131:58879 |
| OpenAlex: | W1983686384 |