Solid-State Redox Switching of Magnetic Exchange and Electronic Conductivity in a Benzoquinoid-Bridged MnII Chain Compound

We demonstrate that incorporation of a redox-active 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 (N,OLH4) with MnIII affords the chain compound Mn(N,OL)(DMSO). Structural and spectroscopic analysis of this compound show the presence of MnII centers bridged by N,OL2– ligands, resulting partially from a spontaneous ligand-to-metal electron transfer. Upon soaking in a solution of the reductant Cp2Co, Mn(N,OL)(DMSO) undergoes a ligand-centered solid-state reduction to [Mn(N,OL)]−, 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 inc...