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• Isomericdiruthenium complexes with bis(ethynyl)pyridine as bridge core 1 – 3 were synthesized and characterized. • Compared with compounds 1 and 2 , compound 3 with linear conjugate structure has higher charge-beneficial capacity. • IVCT band parameters (H ab = 387 cm−1 and Г = 0.08) revealed that 3 + belongs to a weakly coupled class II system. Isomeric diruthenium complexes with bis(ethynyl)pyridine as bridge core [2,6-bis(ethynyl)pyridine (1), 3,5-bis(ethynyl)pyridine (2), 2,5-bis(ethynyl)pyridine (3)] were successfully prepared and characterized by 1H NMR, 13C NMR and elemental analysis. The electrochemical properties of complexes 1–3 were investigated by cyclic voltammetry (CV) and square-wave voltammetry (SWV), and different potential difference values were revealed and affected by N atom position and distance between redox metal centers. Electron absorption spectra showed that the absorption of the linear molecule 3 displayed a red shift relative to that of complexes 1 and 2. The broad near-infrared absorption characteristic of the singly-oxidized complex 3 + revealed the existence of a mixed-valence state, which can be classified as a class II mixed-valence system according to the intervalence charge transfer (IVCT) absorption parameter H ab and Г. These results indicated that 3 has higher conjugation and charge delocalization ability than isomers 1 and 2. Density functional theory (DFT) calculations spin density distribution analysis further confirmed the above results, and time-dependent DFT showed the NIR multi-absorption of complex 3+ , and effectively attributed to Ru–C C→Ru IVCT absorption characteristics. [Display omitted] [ABSTRACT FROM AUTHOR]