Synthesis and Structural Characterization of Neutral and Cationic Alkylaluminum Complexes Based on Bidentate Aminophenolate Ligands
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- 作者：Samuel Dagorne ; Laurent Lavanant ; Richard Welter ; Christophe Chassenieux ; Pierre Haquette ; and Gé ; rard Jaouen
- 刊名：Organometallics
- 出版年：2003
- 出版时间：September 1, 2003
- 年：2003
- 卷：22
- 期：18
- 页码：3732 - 3741
- 全文大小：197K
- 年卷期：v.22,no.18(September 1, 2003)
- ISSN：1520-6041
文摘
The reaction of the aminophenols 2-(CH2L)-6-R-C6H3OH (R = Ph, L = NMe2, 1a; R = tBu,L = NMe2, 1b; R = tBu, L = NC4H8, 1c; R = tBu, L = NC5H10, 1d) with 1 equiv of AlMe3affords the corresponding dimethyl Al complexes {2-(CH2L)-6-R-C6H3O}AlMe2 (R = Ph, L =NMe2, 2a; R = tBu, L = NMe2, 2b; R = tBu, L = NC4H8, 2c; R = tBu, L = NC5H10, 2d) inhigh yields. Compounds 2a-d appear to be monomeric, on the basis of X-ray analysis for2b,d and NMR data for 2a-d, and are stable in the presence of THF. {2-(CH2NMe2)-6-Ph-C6H3O}AlMe2 (2a) cleanly reacts with B(C6F5)3 to yield the dinuclear cationic Al species3a+. X-ray diffraction analysis shows that the cation 3a+ can be seen as an adduct of thethree-coordinate cation {2-(CH2NMe2)-6-Ph-C6H3O}AlMe+ and the neutral precursor 2a, inwhich the two Al centers are connected via a 
2-O aminophenolate bridge. Similarly, thereaction of Al dimethyl complexes 2b-d with B(C6F5)3 yields dinuclear cationic Al species3b-d+/3b'-d'+ (3b+/3b'+ in a 1/1 ratio; 3c,d+/3c',d'+ in a 3/1 ratio, respectively) asdiastereomeric mixtures. Cations 3b-d+/3b'-d'+ adopt a structure similar to that of cation3a+, as determined by X-ray crystallography analysis for 3b'+ and 2D NMR studies for 3a+and 3c,d+/3c',d'+. All the formed dinuclear cations are quite stable and robust in solution,and no fluxional behavior for any of them was observed up to 80 
C in C6D5Br. Cations3b-d+/3b'-d'+ react with a Lewis base such as THF to afford the corresponding THF adductcation 4b-d+ along with 1 equiv of the corresponding neutral precursor 2b-d. In contrast,3a+ reacts with THF to yield unidentified species. 3a+ and 3c,d+/3c',d'+ are inactive inethylene polymerization, but cations 3b-d+/3b'-d'+ polymerize PO with moderate activityto yield low-molecular-weight PPO.
2-O aminophenolate bridge. Similarly, thereaction of Al dimethyl complexes 2b-d with B(C6F5)3 yields dinuclear cationic Al species3b-d+/3b'-d'+ (3b+/3b'+ in a 1/1 ratio; 3c,d+/3c',d'+ in a 3/1 ratio, respectively) asdiastereomeric mixtures. Cations 3b-d+/3b'-d'+ adopt a structure similar to that of cation3a+, as determined by X-ray crystallography analysis for 3b'+ and 2D NMR studies for 3a+and 3c,d+/3c',d'+. All the formed dinuclear cations are quite stable and robust in solution,and no fluxional behavior for any of them was observed up to 80 C in C6D5Br. Cations3b-d+/3b'-d'+ react with a Lewis base such as THF to afford the corresponding THF adductcation 4b-d+ along with 1 equiv of the corresponding neutral precursor 2b-d. In contrast,3a+ reacts with THF to yield unidentified species. 3a+ and 3c,d+/3c',d'+ are inactive inethylene polymerization, but cations 3b-d+/3b'-d'+ polymerize PO with moderate activityto yield low-molecular-weight PPO.