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A novel type of imidazole one-atom bridged cyclopentadienyl ligands and its reaction with Group 4 metal saltsдипломная работа (Специалист)
- Научный руководитель: Borzov Maxim V.
- Автор: Wang Xiaowu
- Тип: Специалист
- Организация, в которой проходила защита: College of Chemistry and Material Science, the North-West University of Xi’an, Taibai Bei Avenue 229, Xi’an 710069, Shaanxi Province, People’s Republic of China
- Год защиты: 2009
- Аннотация: One novel type of imidazole one-atom bridged cyclopentadienyl ligands and its reaction with IVB salts has been established, as well as the studies of their synthesis, structural and reactive activity. The synthetic route of this novel imidazole one-atom bridged cyclopentadienyl ligands has been thoroughly studied. Treatment 1-diethoxylmethylimidazole(1) and 1-dimethoxylmethylimidazole(5) with 6,6-diphenylfulvene (2), 6-monopehylfulvene (11) has been shown to afford pure ligands C5H5CR2-(2-C3H3N2) (R2 = Ph, Ph; Ph, H (4), (12) respectively). The novel bidentate ligands are finally characterized. Reaction of ligands (4), (12) with n-BuLi afford the corresponding dilithium salt (7), (14). Dilithium salt LiC5H4CR2(2-C3H2N2Li) (R2 = Ph, Ph; 7) has been isolated in pure state as an adduct with 2 molecules of THF. Crystal and molecular structure of 7 * 2THF has been established by X-ray diffraction analysis. For this compound, an interesting case of organolithium compound catenation provided by h5-Cp-Li(CN=2)-N(imidazolide) intermolecular interactions has been found. A brief quantum-chemical modeling for (7) revealed a good match of the observed and calculated structural parameters for the h5-Cp-Li(CN=2)-N(imidazolide) moiety and outlined considerable pi-interaction within this fragment. An interesting n-BuLi invoked rearrangement of 1-diethoxymethyl-1H-imidazole (1) or 1-dimethoxylmethyl-1H-imidazole (5) into their 2-isomers (17) and (20) has been observed. The suggested method allows to prepare 2-1H-imidazole carbaldehyde (18) (quantitative acidic hydrolysis of (17) and/or (20)) in a cheap and convenient way comparatively to the literature synthetic routines. Compound (18) isa rather useful pharmaceutical intermediate (20$/g). Attempts to prepare the ligand (F) under various base conditions proved to be a failure. Under the gas chromatograph column conditions, compound (17) has been proved to undergo a quantitative conversion into 4,8-diethoxy-3a,4,7a,8-tetrahydro-1,3a,5,7a-tetraza-s-indacenes [19a (4RS,8RS)- and 19b (4R,8S)-diastereomers]. Crystal and molecular structures of (17) and 19(b) have been established by X-ray diffraction analysis. For compound (13), NMR-time scale slow-limit tautomeric rearrangement has been observed. Crystal structure of (13) has been established by X-ray diffraction analysis. Attempts to develop an alternative route to the 1H-imidazol-2-yl side-chain functionalized cyclopentadienes (C) failed. Reaction of dilithium salt (7) with the Group 4 metal tetrahalides, ZrCl4*2THF and TiC4, has been studied. Formation of supposedly polymeric products has been postulated in this case. Treatment of bidentate ligands (12 and 4) with Ti(NEt2)4 (9) in toluene at 80-90 C has been shown to lead to pure {[2-h5-cyclopenta-2,4-dienyl]-mono (or di-) phenylmethyl]-lH-imidazole-KN]}bis(N,N-diehtylamido)titaniums(+4), C23H32N4Ti (15) and C39H37N4Ti (10) in 60 and 50% yields, respectively. Crystal structure of (15) has been established by X-ray diffraction analysis. The Ti-linked amido-nitrogen atoms of NEt2 and imidazole groups have been proved to possess planar environments what is indicative of an additional n-donation from all of the amido-type groups towards the Ti-center. Thus, the titanium atom in (15) formally possesses an 18e- shell, that presents a rather untypical phenomenon in Ti(IV) organochemistry. Generally, it possesses a 16 e- shell.
- Добавил в систему: Борзов Максим Владимирович
Прикрепленные файлы
| № | Имя | Описание | Имя файла | Размер | Добавлен |
|---|---|---|---|---|---|
| 1. | Полный текст | WangXiaowu.pdf | 33,9 МБ | 26 ноября 2018 [BorzovMV] |