Mechanochemical assembly of hybrid organic–organometallic materials. Solid–solid reactions of 1,1′-di-pyridyl-ferrocene with organic acids

Abstract

Manual kneading of the organometallic complex [Fe(η⁵-C₅H₄-C₅H₄N)₂] with solid fumaric, succinic, tridecanedioic, terephthalic, trimesic and thiophene-2,5-dicarboxylic acids generated the corresponding adducts, whether salts or molecular complexes: [Fe(η⁵-C₅H₄-C₅H₄N)(η⁵-C₅H₄-C₅H₄NH)][HOOC(CH)₂COO]·CH₃OH, [Fe(η⁵-C₅H₄-C₅H₄N)(η⁵-C₅H₄-C₅H₄NH)][HOOC(CH₂)₂COO]·[HOOC(CH₂)₂COOH], [Fe(η⁵-C₅H₄-C₅H₄N)₂]·[HOOC(CH₂)₁₁COOH]·2CH₃OH, [Fe(η⁵-C₅H₄-C₅H₄N)₂]·[HOOC(C₆H₄)COOH], [Fe(η⁵-C₅H₄-C₅H₄NH)₂][C₆H₃(COOH)₂(COO)]₂ and 3{[Fe(η⁵-C₅H₄-C₅H₄N)(η⁵-C₅H₄-C₅H₄NH)][HOOC(SC₄H₂)COO]}·[Fe(η⁵-C₅H₄-C₅H₄N)₂]·2[HOOC(SC₄H₂)COOH]. Direct reaction in solution yielded the same compounds, which were characterized by single crystal X-ray diffraction, thus allowing comparison of observed and calculated powder diffraction patterns. Kneading of the organometallic complex with maleic acid, on the other hand, yielded a different product from the one obtained via reaction in solution, which was characterized by single crystal X-ray diffraction as the salt [Fe(η⁵-C₅H₄-C₅H₄NH)₂][HOOC(CH)₂COO]₂. The solid–solid processes described herein imply molecular diffusion through the lattice and breaking and reassembling of hydrogen bonded networks with or without proton transfer from acid to base.