Experimental and Theoretical Studies of the Hydrogenation of 伪,尾-Unsaturated Acids by an 18e Hydride Carbonylniobocene Complex

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• 作者：Antonio Anti帽olo ; Kh茅didja Dorani ; Santiago Garc铆a-Yuste ; Isabel L贸pez-Solera ; Antonio Otero ; Mar铆a Teresa Tercero-Morales ; G谩bor Kov谩cs ; Gregori Ujaque ; Agust铆 Lled贸s
• 刊名：Organometallics
• 出版年：2012
• 出版时间：July 23, 2012
• 年：2012
• 卷：31
• 期：14
• 页码：5177-5184
• 全文大小：361K
• 年卷期：v.31,no.14(July 23, 2012)
• ISSN：1520-6041

文摘

The reaction of the niobocene complex [Nb(畏⁵-C₅H₄SiMe₃)₂(H)(CO)] (1) with 伪,尾-unsaturated acids, namely, fumaric and maleic acids, and methylfumarate ester yielded the corresponding carboxylato-containing niobocene derivatives [Nb(畏⁵-C₅H₄SiMe₃)₂(魏¹-O-OOC-CH₂-CH₂-R)(CO)] (R = COOH (2); R = COOMe (3)), resulting from the hydrogenation of the C鈺怌 bond and the consequent coordination of a carboxylato moiety on the Nb center. The process represents the first reported example of the hydrogenation of 伪,尾-unsaturated acids mediated by a hydride niobocene complex. Spectroscopic and theoretical studies at the DFT level have allowed for proposing a plausible reaction mechanism. Initial coordination of the C鈺怌 bond to the Nb center is followed by the insertion of this bond into the Nb鈥揌 bond, and the reaction is completed by a proton transfer from the carboxylic moiety to the 伪-carbon of the alkyl moiety, giving rise to the final 魏¹-carboxylato ligand.