Study of Ketene-Bridged Ditungsten Complexes

• Main Authors: Wang, Jun-Jieh, 王俊傑
• Other Authors: Lin Ying-Chih
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/62534719013321231938

碩士 === 國立臺灣大學 === 化學系研究所 === 85 === The reaction of Cp(CO)3WNa (1) with diiodomethane in CH3OH for three days at 253 K gave ketene-bridged ditungsten complex Cp(CO)3W[μ2-η1:η2-CH2C(O)]W(C O)2Cp (3) exhibiting η2-acyl feature. When the same reaction was carried out in CH3CN, the ditungsten acetylide complex [Cp(CO)3W]2(μ2-C≡C) (4) was obtai ned. Complex 4 transformed to 3 upon dissolution in CH3CN at room temperature. Treatment of 3 with two-electron donor ligands such as phosphines, isocyanide , and carbon oxide gave coordinated products Cp(CO)3W[μ2-CH2C(O)]W(CO)2LCp ( 6, L = PR3; 7, L = CNR; 8, L = CO). The tetratungsten complexes {Cp(CO)3W[μ2- CH2C(O)]W(CO)2Cp}2 (μ2-L) (9, L = dppe; 10, L = CN(CH2)6NC) were also obtaine d from 3 with bidentate four-electron donor ligands. When complexes 6-7 dissol ved in CH3Cl, cleavage of the W-CH2 bond lead to the mononuclear complexes Cp( CO)2LWC(O)CH3 (11, L = PR3; 12, L = CNR) and Cp(CO)3WCl (23). The same reactio n of complexes 9-10 gave ligand-bridged complexes [CH3C(O)W(CO)2Cp]2(μ2-L) (1 3, L = dppe; 14, L = CN(CH2)6NC) and 23 , but treatment of complex 8 with H2O gave nucleophilic product Cp(CO)3WCH2C(O)OH (26) and Cp(CO)WH (24). The react ions of complex 3 with various hetero-cumulenes afforded different results. Wh en 3 reacted with allene, η3-allylic complex Cp(CO)3W[μ2-η1:η3-CH2C(O)(C3H 4)]W(CO)2Cp (16) was obtained by coupling of allene with the acyl group. In th e reaction of 3 with CS2, cleavage of the CS bond was accompanied with inserti on of the sulfer atom into the W-acyl bond to afford Cp(CO)3W[μ2-CH2C(O)S]W(C O)2(CS)Cp (18). The reaction of 3 with thioisocyanate gave thio-ketene-bridged complex Cp(CO)3W[μ2-η1:η2-SC(CH2)]W(CO)2Cp (20) in which the CS portion be haved as a four-electron donor, and the reaction could possibly proceed via a [2+2] cycloaddition of RNCS and ketene-unit to generate RNCO and thioketene-li ke product. Treatment of complex 18 with nucleophiles such as H2O, alcohols, a nd amines for eight hours at 323 K gave carboxylic acid, esters, and amides by nucleophilic substitution. These results were similar to the same reaction ca rried out in complex 8. Reaction of complex 20 with CF3COOH afforded the proto nation product Cp(CO)3W[μ2-η1:η2-SC(CF3COO)(CH3)]W(CO)2Cp (31) which was ob eying Markovnikov's rule. If non-coordinated anion BF4- is used, an ionic prod uct {Cp(CO)3W[μ2-η1:η2-SC(CH3)]W(CO)2Cp}BF4 (32) would be obtained. Complex 32 could be reversible to 20 in the presence of amines.