We have succeeded in constructing an electron-transfer gating system involving a copper complex, 1.BF4, that is regulated by the rotational motion of a pyridylpyrimidine ligand. 4-Methyl-2-(2'-pyridyl)pyrimidine confined between two bulky groups underwent a dynamic process derived from pyrimidine-ring coordination inversion between inner and outer isomers, and these isomers interconverted with each other in solution with a barrier of 73 kJ mol(-1) at 293 K. As the ring-inversion process induces a change in redox potential on the copper center, electron transfer between V and the electrode can be gated through on/off control of the inversion by changing the temperature, resulting in a -0.14 V shift of the electrode potential.