Steric Interference on the Redox-conjugated Pyrimidine Ring Rotation of Mono- and Dinuclear Copper Complexes with (4-Methyl-2-pyrimidinyl)imine Ligands
Steric Interference on the Redox-conjugated Pyrimidine Ring Rotation of Mono- and Dinuclear Copper Complexes with (4-Methyl-2-pyrimidinyl)imine Ligands
Steric Interference on the Redox-conjugated Pyrimidine Ring Rotation of Mono- and Dinuclear Copper Complexes with (4-Methyl-2-pyrimidinyl)imine Ligands
A mononuclear copper(I) complex with N-[(4-methyl-2-pyrimidinyl)methylene]-p-toluidine (1·BF4) and a dinuclear copper(I) complex with N,N′-bis[(4-methyl-2-pyrimidinyl)methylene]-p-phenylenediamine (2·(BF4)2) were synthesized as BF4− salts to evaluate the influence of the imine moiety on the pyrimidine ring rotation isomerism. 1·BF4 existed in solution as a mixture of two isomers; 2·(BF4)2 was present as a mixture of three isomers. The redox potentials of the copper centers were changed by pyrimidine ring rotation. Comparison of 1+ and 22+ indicated that increasing the steric congestion around the copper center increased the o/i isomer ratio; the redox potentials of both the o- and i-isomers shifted in the positive direction, and the CuII/I redox reaction became slower.