The five-coordinate iron-dithiolate complex (N,N'-4,7-bis-(2'-methyl-2'-mercatopropyl)-1-thia-4,7-diazacyclononane)i ron(III), [LFe](+), has been isolated as the triflate salt from reaction of the previously reported LFeCl with thallium triflate. Spectroscopic characterization confirms an S = 1/2 ground state in non-coordinating solvents with room temperature mu(eff) = 1.78 mu(B) and electron paramagnetic resonance (EPR) derived g-values of g(1) = 2.04, g(2) = 2.02 and g(3) = 2.01. [LFe](+) binds a variety of coordinating solvents resulting in six-coordinate complexes [LFe-solvent](+). In acetonitrile the low-spin [LFe-NCMe](+) (g(1) = 2.27, g(2) = 2.18, and g(3) = 1.98) is in equilibrium with [LFe](+) with a binding constant of K-eq = 4.7 at room temperature. Binding of H2O, DMF, methanol, DMSO, and pyridine to [LFe]+ yields high-spin six-coordinate complexes with EPR spectra that display significant strain in the rhombic zero-field splitting term E/D. Addition of 1 equiv of triflic acid to the previously reported diiron species (LFe)(2)O results in the formation of [(LFe)(2)OH]OTf, which has been characterized by X-ray crystallography. The aqueous chemistry of [LFe](+) reveals three distinct species as a function of pH: [LFe-OH2](+), [(LFe)(2)OH]OTf, and (LFe)(2)O. The pK(a) values for [LFe-OH2](+) and [(LFe)(2)OH]OTf are 5.4 +/- 0.1 and 6.52 +/- 0.05, respectively.