摘要
采用量子化学ab initio法对具有甲氧基的碳、氮双自由基邻、间、对二甲氧基亚甲基苯及衍生物体系基态自旋耦合规律进行研究,得到非平面共轭体系中自由基之间磁性耦合的拓朴规则:共轭体系中,两个自由基之间以偶数个碳原子耦合,则有效交换积分J_(ij)<0,体系具有低自旋基态;两个自由基之间以奇数个碳原子耦合,则J_(ij)>O,体系具有高自旅基态.自由基性质对自旋耦合的影响较大,正离子自由基间磁性耦合能力较强,这些结论为有机磁性材料的分子设计与实验合成提供了理论依据.
Spin coupling rules for the ground state of the carbon or nitrogen biradicals of o - , m - , p -bimethoxymethanobenzene and its derivatives containing the carbon, nitrogen biradicals have been studied quantum chemical ab initio methods. It is proved that there are topological rules for the magnetic couplings between the radicals of nonplane conjugated systems: In conjugated system, the effective exchange integrals of radical sites through the even number of carbons with a π - electron network are negative in sign, which means the low spin state corresponds to a stable ground state, while those through odd carbon atoms are positive in sign, (i.e., the high spin state corresponds to a stable ground state). The properties of radical have obvious influence on the spin coupling. Stronger ferromagnetic coupling occurs between positive ion radicals, which provides theoretical guide for molecular design and experimental synthesis of organic magnetic materials.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2000年第5期594-597,共4页
Acta Chimica Sinica
