Department of Chemistry and Pharmacy & Interdisciplinary Center for Molecular Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.
J Am Chem Soc. 2010 Jul 7;132(26):9078-86. doi: 10.1021/ja101856j.
We report for the first time the versatile Ce(2)@I(h)-C(80) building block toward synthesizing a novel electron donor-acceptor conjugate, Ce(2)@I(h)-C(80)-ZnP (1). A systematic investigation of the charge transfer chemistry documents a reductive charge transfer (i.e., formation of (Ce(2)@I(h)-C(80))(-)-(ZnP)(+)) in nonpolar media (i.e., toluene/THF), while an oxidative charge transfer (i.e., formation of (Ce(2)@I(h)-C(80))(+)-(ZnP)(-)) dominates in polar media (i.e., benzonitrile/DMF). Reduction of the Ce(2) cluster, which is highly localized and collinearly arranged with respect to the quaternary bridge carbon, is sufficiently exothermic in all solvents. Notably weak is the electronic coupling between the Ce(2) cluster and the electron-donating ZnP. The oxidation of C(80)(6-) and the simultaneous reduction of ZnP, on the other hand, necessitate solvent stabilization. In such a case, the strongly exothermic (Ce(2)@I(h)-C(80))(-)-(ZnP)(+) radical ion pair state formation is compensated within the framework of a nonadiabatic charge transfer by a C(80)(6-)/ZnP electronic matrix element, as the sum of good overlap and short distance, that exceeds that for Ce(2)/ZnP.
我们首次报道了多功能 Ce(2)@I(h)-C(80) 构建基块，用于合成新型电子给体-受体轭合物 Ce(2)@I(h)-C(80)-ZnP（1）。我们对电荷转移化学进行了系统研究，记录了在非极性介质（即甲苯/THF）中发生还原电荷转移（即形成（Ce(2)@I(h)-C(80))(-)-(ZnP)(+))，而在极性介质（即苯腈/DMF）中发生氧化电荷转移（即形成（Ce(2)@I(h)-C(80))(+)-(ZnP)(-))。[Ce(2)]6+ 簇的还原，对于四元桥碳来说，其高度局域且共线排列，在所有溶剂中都是足够放热的。值得注意的是，[Ce(2)]6+ 簇与供电子 ZnP 之间的电子耦合很弱。另一方面，C(80)(6-)的氧化和 ZnP 的同时还原需要溶剂稳定化。在这种情况下，强放热的（Ce(2)@I(h)-C(80))(-)-(ZnP)(+)自由基离子对态形成通过非绝热电荷转移，由 C(80)(6-)/ZnP 电子矩阵元来补偿，该矩阵元是良好重叠和短距离的总和，超过了[Ce(2)]6+/ZnP 的总和。
