Ortu Fabrizio, Liu Jingjing, Burton Matthew, Fowler Jonathan M, Formanuik Alasdair, Boulon Marie-Emmanuelle, Chilton Nicholas F, Mills David P
School of Chemistry, The University of Manchester , Oxford Road, Manchester M13 9PL, U.K.
Inorg Chem. 2017 Mar 6;56(5):2496-2505. doi: 10.1021/acs.inorgchem.6b02683. Epub 2017 Feb 16.
A series of lanthanide complexes bearing organic radical ligands, [Ln(Cp)(bipy·)] [Ln = La, Cp = Cp (1); Ln = Ce, Cp = Cp (2); Ln = Ce, Cp = Cp″ (3); Ln = Ce, Cp = Cp‴ (4)] [Cp = {CHBu-1,3}; Cp″ = {CH(SiMe)-1,3}; Cp‴ = {CH(SiMe)-1,2,4}; bipy = 2,2'-bipyridyl], were prepared by reduction of [Ln(Cp)(μ-I)] or [Ce(Cp‴)(I) (THF)] with KC in the presence of bipy (THF = tetrahydrofuran). Complexes 1-4 were thoroughly characterized by structural, spectroscopic, and computational methods, together with magnetism and cyclic voltammetry, to define an unambiguous Ln(III)/bipy· radical formulation. These complexes can act as selective reducing agents; for example, the reaction of 3 with benzophenone gives [{Ce(Cp")(bipy)}{κ-O,O'-OPhC(CH)CPhO}] (7), a rare example of a "head-to-tail" coupling product. We estimate the intramolecular exchange coupling for 2-4 using multiconfigurational and spin Hamiltonian methods and find that the commonly used Lines-type isotropic exchange is not appropriate, even for single 4f e/organic radical pairs.
一系列带有有机自由基配体的镧系配合物，[Ln(Cp)(bipy·)] [Ln = La，Cp = Cp (1)；Ln = Ce，Cp = Cp (2)；Ln = Ce，Cp = Cp″ (3)；Ln = Ce，Cp = Cp‴ (4)] [Cp = {CHBu-1,3}；Cp″ = {CH(SiMe)-1,3}；Cp‴ = {CH(SiMe)-1,2,4}；bipy = 2,2'-联吡啶]，是通过在联吡啶存在下用KC还原[Ln(Cp)(μ-I)]或[Ce(Cp‴)(I) (THF)]制备的（THF = 四氢呋喃）。配合物1 - 4通过结构、光谱和计算方法以及磁性和循环伏安法进行了全面表征，以确定明确的Ln(III)/bipy·自由基结构。这些配合物可以作为选择性还原剂；例如，3与二苯甲酮反应得到[{Ce(Cp")(bipy)}{κ-O,O'-OPhC(CH)CPhO}] (7)，这是一个罕见的“头对尾”偶联产物的例子。我们使用多组态和自旋哈密顿方法估计了2 - 4的分子内交换耦合，发现即使对于单个4f e/有机自由基对，常用的Lines型各向同性交换也不合适。
