Iron/2,6‐Di(pyrazol‐1‐yl)pyridine Complexes with a Discotic Pattern of Alkyl or Alkynyl Substituents

2,6-Di(4-iodopyrazol-1-yl)pyridine is converted to 2,6-di(4-{alkyn-1-yl}pyrazol-1-yl)pyridine (L1R; R’=CnH2n−3, n=12, 14, 16) derivatives by Sonogashira reactions. Hydrogenation of these intermediates yields the corresponding 2,6-di(4-alkylpyrazol-1-yl)pyridine (L2R; R=CnH2n+1) derivatives. Homoleptic Fe[BF4]2 complexes all ligands were prepared, bearing four long chain substituents in a discotic-type array. Crystallographic data from two L1R imply alkynyl do not undergo intermolecular interdigitation solid state, which could explain lower crystallinity and ill-defined spin-crossover their iron complexes. Solid [Fe(L2R)2][BF4]2 (n=12 14) exhibit an irreversible, abrupt low→high-spin event near 350 K, associated with solvent loss may involve disordering alkyl conformations. No mesophase behavior was observed any compounds.