Dehydropolymerization of H<sub>3</sub>B·NMeH<sub>2</sub> To Form Polyaminoboranes Using [Rh(Xantphos-alkyl)] Catalysts
作者:Gemma M. Adams、Annie L. Colebatch、Joseph T. Skornia、Alasdair I. McKay、Heather C. Johnson、Guy C. Lloyd−Jones、Stuart A. Macgregor、Nicholas A. Beattie、Andrew S. Weller
DOI:10.1021/jacs.7b11975
日期:2018.1.31
cationic 6 (Mn = 9000 g mol-1, Đ = 2.9). For 6 isotopic labeling studies suggest a rate-determining NH activation, while speciation studies, coupled with DFT calculations, show the formation of a dimetalloborylene [Rh(κ3-P,O,P-Xantphos-iPr)}2B]+ as the, likely dormant, end product of catalysis. A dual mechanism is proposed for dehydropolymerization in which neutral hydrides (formed by hydride transfer
据报道,使用基于中性和阳离子 Rh(Xantphos-R)} 片段的催化剂,其中 PR2 基团选自 Et, iPr 和 tBu。最有效的系统基于 Rh(Xantphos-iPr)},即 [Rh(κ3-P,O,P-Xantphos-iPr)(H)2(η1-H3B·NMe3)][BArF4], 6 , 和 Rh(κ3-P,O,P-Xantphos-iPr)H, 11. 虽然 H2 演化动力学表明两者都是快速催化剂 (ToF ≈ 1500 h-1),但脱氢聚合的聚合物生长动力学表明了一个经典的链增长过程中性 11 (Mn = 28 000 g mol-1, Đ = 1.9) 促进聚合度明显高于阳离子 6 (Mn = 9000 g mol-1, Đ = 2.9)。6 项同位素标记研究表明 NH 活化速率决定性,而形态研究和 DFT 计算表明,二金属亚硼烯 [Rh(κ3-P,O,P-Xantphos-iPr)}2B]+