Synthesis, X-ray Characterization, and Reactivity of 伪-Aminoacidato Ethoxide Complexes of Niobium(V) and Tantalum(V)

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• 作者：Mohammad Hayatifar ; Fabio Marchetti ; Guido Pampaloni ; Stefano Zacchini
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：April 1, 2013
• 年：2013
• 卷：52
• 期：7
• 页码：4017-4025
• 全文大小：386K
• 年卷期：v.52,no.7(April 1, 2013)
• ISSN：1520-510X

文摘

High yields of the ethoxo-伪-aminoacidates of the general formula M(OEt)₄[OC(O)CHRNHR鈥?魏O,魏N] (M = Nb, R = CH₂Ph, R鈥?= H, 2; R = CHMe₂, R鈥?= H, 3; R = CH₂CHMe₂, R鈥?= H, 4; R = H, R鈥?= Me, 5; R = CH₂CH₂SMe, R鈥?= H, 6; M = Ta, R = CH₂Ph, R鈥?= H, 7; R = CH₂CH₂SMe, R鈥?= H, 8) and M(OEt)₄(OC(O)CH(CH₂CH₂CH₂)NH-魏O,魏N) (M = Nb, 9; Ta, 10) have been obtained by the reaction of the l-enantiopure 伪-amino acid (or sarcosine) with a slight molar excess of M(OEt)₅ (M = Nb, 1a; Ta, 1b) in a dichloromethane solution. The new complexes 2鈥?b>10 have been fully characterized by spectroscopic and analytical methods and by X-ray diffraction for 2 and 7鈥?b>9. Such X-ray structures are the first ones ever reported for niobium and tantalum coordination compounds containing an 伪-aminoacidato ligand. The early鈥搇ate heterobimetallic derivative Ta(OEt)₄[O₂CCH(NH₂)CH₂CH₂S(CH₃)(AuCl)] (11) has been prepared by the reaction of 8 with a stoichiometric amount of Au(CO)Cl. The bulk polymerization of d,l-lactide initiated by complexes 2 and 7 gave a slightly heterotactic enchainment (P_r = 0.54 and 0.63, respectively), whereas complexes 1a and 1b formed fully atactic polylactide with P_r 鈮?0.4.