Guanidinophosphazenes: Design, Synthesis, and Basicity in THF and in the Gas Phase
作者:Alexander A. Kolomeitsev、Ilmar A. Koppel、Toomas Rodima、Jan Barten、Enno Lork、Gerd-Volker Röschenthaler、Ivari Kaljurand、Agnes Kütt、Ivar Koppel、Vahur Mäemets、Ivo Leito
DOI:10.1021/ja053543n
日期:2005.12.1
dimethylamino (or tetramethylguanidino) fragments are replaced by methylated triguanide fragments, (tmg)2C=N-. The gas-phase basicity (around 300-310 kcal/mol) of the resulting base, [(tmg)2C=N-]3P=NH, having only one phosphorus atom, is predicted to exceed the basicity of (dma)3P=NH by more than 40 powers of 10 and to surpass also the basicity of the widely used commercial [(dma)3P=N]3P=N-t-Bu (t-BuP4)
提出了创建新一代非离子超强碱的原理。它基于使用四甲基胍或容易获得的 1,3-二甲基咪唑烷-2-亚胺将四烷基胍基、1,3-二甲基咪唑烷-2-亚氨基或双(四烷基胍基)carbimino 基团连接到亚氨基正膦基团的磷原子上。已经合成了七种新的非离子超碱性磷腈碱,四甲基胍基取代了 P 原子。它们的碱强度是通过分光光度法滴定在四氢呋喃 (THF) 溶液中确定的,并与专为本研究设计的八种参考超碱 P2- 和 P4-亚氨基正膦进行比较。几种胍基和N',N',N'',N''的气相碱度 计算了-四甲基胍基(tmg)-取代的磷腈及其环状类似物,并确定了(tmg)3P=Nt-Bu和(tmg)3P=Nt-Bu x HBF4的晶体结构。对于 THF 介质中的四甲基胍基,该原理的巨大碱度增加效果得到了实验验证:当从 (dma)3P=Nt-Bu (pKalpha = 18.9) 移动到 (tmg)3P=Nt-Bu 时,碱度增加(