A New Class of Easily Generated TCNQ²⁻-Based Coordination Polymers

New types of coordination polymers containing [M(TCNQ)] sheets in which the TCNQ component is present as the little known dianion TCNQ²⁻ are obtained in a very simple manner using readily available TCNQH₂ (i.e. 1,4-(NC)₂CH·C₆H₄·CH(CN)₂) as the starting material. Above and below the metal centers in the sheets, a range of pyridine derivatives can be attached, some terminal and some acting as pillars linking sheet to sheet to form a 3D coordination network. The following compounds, generally in solvated form, were isolated and structurally characterized[M(TCNQ)(pyridine)₂] (M = Mn or Zn), [M(TCNQ)(quinoline)₂] (M = Co or Zn), [Mn(TCNQ)(4-methylpyridine)₂], [Zn(TCNQ)(4-phenylpyridine)₂], [Zn(TCNQ)(isoquinoline)₂], [Zn(TCNQ)(nicotinamide)₂], [M(TCNQ)(bipy)] (M = Mn, Fe, Zn, Cd, and bipy =4,4′-bipyridine, which links sheet to sheet to generate 3D coordination polymers), [Zn(TCNQ)(bpe)] (bpe = 1,2-bis(4-pyridyl)ethylene), and [Zn(CH₃OH)(TCNQ)(Obip)_1/2] (Obip = 4,4′-bipyridine di-N-oxide). The TCNQH₂/TCNQ²⁻ approach opens the way to numerous new types of crystalline and structurally characterizable TCNQ-based networks (and not just the sheet structures that are the focus of this preliminary report) that may lead to solids with unusual and useful electronic/magnetic properties.