A molecular Ce2@I(h)-C80 switch--unprecedented oxidative pathway in photoinduced charge transfer reactivity.
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)](6+) 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)](6+) 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)](6+)/ZnP.
Guldi
Dirk M
DM
Department of Chemistry and Pharmacy & Interdisciplinary Center for Molecular Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany. guldi@chemie.uni-erlangen.de
Feng
Lai
L
Radhakrishnan
Shankara Gayathri
SG
Nikawa
Hidefumi
H
Yamada
Michio
M
Mizorogi
Naomi
N
Tsuchiya
Takahiro
T
Akasaka
Takeshi
T
Nagase
Shigeru
S
Herranz
M Angeles
MA
Martín
Nazario
N