Access to a new family of thioether-linked PSRT ligands, 4-substituted-3,5-bis{[(2-pyridylmethyl)sulfanyl]methyl}-4H-1,2,4-triazoles (analogues of the previously studied amino-linked PMRT ligands), has been established. Four such ligands have been prepared, PSPhT, PSiBuT, PSt-BuPhT, and PSMePhT, with R = Ph, Bu-i, (t-B)uPh, and MePh, respectively. Three dinuclear colorless to pale green iron(II) complexes, [Fe-2(II)(PSRT)2](BF4)4 center dot solvent, featuring N4S2 donor sets, were prepared. Single-crystal structure determinations on [Fe-2(II)(PSPhT)(2)](BF4)(4)center dot 2MeCN center dot H2O, [Fe-2(II)(PSPhT)(2)](BF4)4 center dot 21/2MeCN center dot 1/2H2O center dot THF, [FeII2(PSMePhT)(2)](BF4)(4)center dot 2MeCN, and [Fe-2(II)(PSiBuT)(2)](BF4)(4)center dot 4MeCN reveal that all four are stabilized in the [HS-HS] state to 100 K and that both possible binding modes of the bis-terdentate ligands, cis- and trans-axial, are observed. Variable-temperature magnetic susceptibility studies of air-dried crystals (solvatomorphs of the single crystal samples) reveal the first examples of spin crossover (SCO) for a dinuclear iron(II) complex with N4S2 coordination. Specifically, [Fe-2(II)(PSPhT)(2)](BF4)4 center dot 21/2H(2)O undergoes a multistep but complete SCO from [HS-HS] to [LS-LS], whereas [FeII2(PSMePhT)2](BF4)4 center dot 11/2MeCN center dot 2H(2)O exhibits a half-SCO from [HS-HS] to [HS-LS]. In contrast, [Fe-2(II)(PSiBuT)2](BF4)4 center dot MeCN center dot H2O remains [HS-HS] down to 50 K. The reflectance spectrum of pale green [FeII2(PSPhT)2](BF4)4 center dot 1/2CHCl3 center dot 21/2H2O (solvatomorph A) reveals a trace of LS character (572 nm band (1)A(1g) -> T-1(1g)). Evans 1H NMR method and UVvis spectroscopy studies revealed that on cooling dark green acetonitrile solutions of these complexes from 313 to 233 K, all three undergo SCO centered at or near room temperature. The tendency of the complexes to go LS in solution reflects the electronic impact of R on the s-donor strength of the PSRT ligand, whereas the opposite trend in stabilization of the LS state is seen in the solid state, where crystal packing effects, of the R group and solvent content, dominate the SCO behavior.