Fluxional Behavior of a Cadmium Zwitterion Complex: Proton Transport and Tautomerism in Methylene Chloride Solution

The synthesis and structure of the tautomeric Cd(II) isoindoline
zwitterion coordination compound [Cd(4‘-MeLH)(NO3)2]·CH3OH (4‘-MeLH = 1,3-bis{2-(4-methylpyridyl)imino}isoindoline) are reported.
In methylene chloride solution, tautomer interconversion occurs
as the N−H proton moves between the identical imine nitrogen
atoms. We report the kinetics of proton transfer as followed by
variable temperature 1H NMR spectroscopy and demonstrate that
methanol of solvation and adventitious water facilitate rapid proton
transfer.

本文报道了互变异构型镉(II)异吲哚啉两性离子配位化合物[Cd(4‘-MeLH)(NO3)2]·CH3OH（其中4‘-MeLH代表1,3-双{2-(4-甲基吡啶基)亚胺基}异吲哚啉）的合成与结构。在二氯甲烷溶液中，当N-H质子在两个等价的亚胺氮原子间迁移时，会发生互变异构体的相互转化。本文采用变温核磁共振氢谱(1H NMR)追踪质子转移过程，报道了其动力学特征，并证实溶剂化甲醇与痕量外来水可促进质子转移的快速进行。