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The 1: 1 assembly of an electron donor (D) and electron acceptor (A) results in a D+A– charge transfer ion set, contingent upon the intrinsic highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels and packing structure. When these form charge-transfer one-dimensional (1d) chains, crystallization is often challenging, thereby complicating the systematic understanding of the correlation among their structure, charge state, and magnetism. Notably, only a few instances of ionic 1d chains formed by charge transfer between a paddlewheel diruthenium (II, II) complex (Ru2II, II) and an N, N′-dicyanoquinodiimine (DCNQI) or 7, 7, 8, 8-tetracyano-p-quinodimethane (TCNQ) derivative are known. In this study, we report two types of D+A– ionic chains, Ru2 (5-X-2-OHArCO2) 4 (TCNQF2) ·n (solv) (5-X-2-OHArCO2– = 5-halogeno-2-hydroxybenzoate; TCNQF2 = 2, 5-difluorotetracyanoquinodimethane; X = Br, n (solv) = (anisole) (p-xylene), 1; X = Cl, n (solv) = 2 (anisole), 2), which provide an alternating spin chain composed of S = 3/2 for Ru2II, III+ and S = 1/2 TCNQF2·–. Strong antiferromagnetic coupling with J ≈ −100 K was observed between two spin units in both compounds, forming ferrimagnetic chains. The correlation between the structure and exchange coupling of a series of Ru2II, III+–DCNQI·–/TCNQ·– ion chains was investigated. The findings of this study suggest that the Ru–N distance may be the most significant factor influencing the magnitude of the exchange interaction.
Ji et al. (Tue,) studied this question.