Layered ferrimagnets constructed from charge-transferred paddlewheel [Ru2] units and TCNQ derivatives: the importance of interlayer translational distance in determining magnetic ground statet

A donor (D)/acceptor (A) assembly reaction using the paddlewheel-type diruthenium(II,II) complex [Ru-2(3,5-F2PhCO2)(4)(THF)(2)) (3,5-F2PhCO2- = 3,5-difluorobenzoate; abbreviated hereafter as [Ru-2]) as D and 7,7,8,8-tetracyano-p-quinodimethane derivatives (TCNQR(x); 2,5-R -substituted TCNQ) as A in a DCM/TCE or DCE solvent system (DCM = dichloromethane, TCE-1,1,2,2-tetrachloroethane, DCE = 1,2-dichloroethane) led to the formation of DA-type two-dimensional layered compounds [{Ru-2(3,5F(2)PhCO(2))(4))(2){TCNQR(x)}].nsolv (R-x = H-2 (1), R-x = Me-2, (2), and R-x = (OEt)(2) (3)). All the compounds had similar two-dimensional fishnet-type structures, where the two [Ru-2] units were fully coordinated with the four cyano groups of TCNQR(x). The compounds 1-3 were categorized as a one-electron transferred ionic state (1e-I) with D+-A(-)-D formulation (D+equivalent to[Ru-2(II,III)](+); A(-)equivalent to TCNQR(x)(center dot-)). This subunit state formally derived a ferrimagnetically ordered state composed of up-spins with S = 1 for and S = 3/2 for [Ru-2(IIIII)](+) and a down-spin of S = 1/2 for TCNQR(x)(center dot-) with antiferromagnetic superexchange interactions in each layer. Eventually, 1-3 became three-dimensional ferrimagnets with Curie temperatures T-c = 93, 93, and 92 K, respectively, owing to the presence of interlayer ferromagnetic interactions. The interlayer translational distances (t(2)) for the three compounds were 10.56, 10.54, and 10.84 angstrom, respectively, which agreed with the empirical prediction based on the threshold value of t(2) > 10.3 angstrom for a valid ferromagnetic interaction.