We demonstrate that incorporation of a redoxactive benzoquinoid ligand into a one-dimensional chain compound can give rise to a material that exhibits simultaneous solid-state redox switching of optical, magnetic, and electronic properties. Metalation of the ligand 4,5-bis(pyridine-2-carboxamido)-1,2-catechol ((LH4)-L-N,O) with Mn-III affords the chain compound Mn(L-N,L-O)(DMSO). Structural and spectroscopic analysis of this compound show the presence of Mn-II centers bridged by L-N,O(2)- ligands, resulting partially from a spontaneous ligand-to-metal electron transfer. Upon soaking in a solution of the reductant Cp2Co, Mn(L-N,L-O)(DMSO) undergoes a ligand-centered solid-state reduction to [Mn(L-N,L-O)](-), as revealed by a suite of techniques, including Raman and X-ray absorption spectroscopy. The ligand-based reduction engenders a dramatic modulation of the physical properties of the chain compound. An electrochromic response, evidenced by a color change from dark green to dark purple is accompanied by a nearly 40-fold increase in magnetic coupling strength, from J = -0.38(1) to -15.6(2) cm(-1), and a 10,000-fold increase in electronic conductivity, from sigma = 2.33(1) x 10(-12) S/cm (E-a = 0.64(1) eV) to 8.61(1) x 10(-8) S/cm (E-a = 0.39(1) eV). Importantly, the chemical reduction is reversible: treatment of the reduced compound with [Cp2Fe](+) regenerates the oxidized chain. Taken together, these results highlight the ability of benzoquinoid ligands to facilitate solid-state ligand-based redox reactions in nonporous coordination solids, giving rise to reversible switching of optical properties, magnetic exchange interactions, and electronic conductivity.