Manipulating the Spin States of Ru 2 V -Based Compounds: A Dual Pathway via Redox Chemistry and Thermal Activation

In this article, a series of MII-CN-Ru2V (M = Fe, Ru) compounds and their one-electron oxidation compounds were synthesized and fully characterized, namely, Cp5(modppe)Fe-(μ-CN)-Ru2(DiMeOap-4-Me)3(OAc)BF4n (1BF4n), Cp5(modppe)Fe-(μ-CN)-Ru2(ap-4-Me)2(OAc)2(H2O)PF6n (2PF6n), and Cp5(modppe)Ru-(μ-CN)-Ru2(DiMeOap-4-Me)3(OAc)PF6n (3PF6n) (n = 1, 2; Cp5 = 1,2,3,4,5-pentamethyl-cyclopentadienyl, modppe = 1,2-bis(di(4-methoxyphenyl)-phosphino)ethane, DiMeOap-4-Me = 2-(3, 5-dimethoxy)anilino-4-methylpyridine, ap-4-Me = 2-anilino-4-methylpyridine, OAc = CH3COO). The analysis of data shows that the electron configurations of Ru2V in 1BF4, 2PF6, and 3PF6 with the structure of MII-CN-Ru2V (M = Ru, Fe) are high spin (σ2π4δ2)π*2δ* (SRu2 = 3/2). Upon one-electron oxidation, compound 1BF42 exhibits temperature-dependent spin crossover behavior for the Ru2V unit from low spin π*3 (SRu2 = 1/2) to high spin π*2δ* (SRu2 = 3/2), whereas the Ru2 unit in 2PF62 and 3PF62 are assigned as high spin π*2δ* (SRu2 = 3/2) Ru2V and π*2 (SRu2 = 1) Ru2VI, respectively, confirmed by single-crystal X-ray diffraction structure analyses, infrared microspectroscopy, and magnetic analyses and supported by the TDDFT calculations. To the best of our knowledge, the pair of complexes 1BF4/1BF42 is the first example of a spin-state transition initiated by the redox process of an organometallic substituent.