Metamagnetism with TN = 97 K in a layered assembly of paddlewheel [Ru2] units and TCNQ: An empirical rule for interlayer distances determining the magnetic ground state

Abstract

A donor (D)/acceptor (A) assembly reaction of the paddlewheel-type diruthenium(II,II) complex [Ru2(m-ClPhCO2)4(THF)2] (m-ClPhCO2 = meta-chlorobenzoate; abbreviated hereafter as [Ru2]) with 2,5-dimethoxy-7,7,8,8-tetracyano-p-quinodimethane (TCNQ(MeO)2) in a dichloromethane (DCM)/1,1,2,2tetrachloroethane (TCE) solvent system led to the formation of a two-dimensional layered D2A compound with crystallization solvents located between layers: [{Ru2(m-ClPhCO2)4}2{TCNQ(MeO)2}]3.3DCM2TCE (1). Compound 1 undergoes an intra-lattice one-electron transfer to form a charge-distributed state with the formula [{RuII,III2 }+-TCNQ-{RuII,II2 }] with intra-layer ferrimagnetic spin ordering through dp*-pp* orbital overlap that results in ferrimagnetic arrangement with antiferromagnetic interactions over heterospins of S = 1 for [RuII,II2 ] and S = 3/2 for [RuII,III2 ] via S = 1/2 for TCNQ. Consequently, because of the presence of interlayer antiferromagnetic interactions, 1 has an antiferromagnetic ground state with TN = 97 K. On applying a field of less than 0.5 T, a spin flip is induced, yielding a field-induced ferrimagnet (a type of metamagnet) with a large coercive field of 1.2 T at 1.8 K. Compound 1 has interlayer translational (i.e., interlayer [Ru2] [Ru2] or TCNQ TCNQ distance) (l2) and interlayer vertical (l1) distances of 10.30 and 9.82 Å, respectively. By comparison of the magnetostructural correlations of this type of layered magnet, this class of antiferromagnets, including 1, reveal a trend of having l2 r 10.3 Å.