Author:
Molčanov Krešimir,Babić Darko,Kojić-Prodić Biserka,Stare Jernej,Maltar-Strmečki Nadica,Androš Lidija
Abstract
A crystal engineering approach is used to stabilize a radical anion in the crystalline state and to modulate the separation distance within π-stacks of anion radicals. Alkali metal salts of 2,3-dicyano-5,6-dichlorosemiquinone (C8Cl2N2O2, DDQ^{\bullet -}) radical anions were prepared and their crystal structures determined: LiDDQ·2H2O·(CH3)2CO, RbDDQ·2H2O and CsDDQ·2H2O. In these structures, stacked dimers of radical anions are formed within π-stacked columns. Within the stacked dimers, interplanar separation distances are significantly shorter than the sum of the van der Waals radii for two C atoms; the shortest is 2.812 Å for the Li salt and the longest is 2.925 Å for the Cs salt. Diamagnetic character, observed by electron paramagnetic resonance spectroscopy, indicates spin-coupling of the unpaired electrons within the radical anion dimer. The electron-rich cyano substituents on DDQ^{\bullet -} influence the electron redistribution within the ring skeleton. The crystalline compounds are also characterized by IR spectroscopy, complemented by quantum-chemical calculations based on both isolated and periodic models.
Publisher
International Union of Crystallography (IUCr)
Subject
Materials Chemistry,Metals and Alloys,Atomic and Molecular Physics, and Optics,Electronic, Optical and Magnetic Materials
Cited by
20 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献