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

Manual kneading of the organometallic complex [Fe(eta(5)-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(eta(5)-C5H4-C5H4N)(eta(5)-C5H4-C5H4NH)][HOOC(CH)(2)COO]center dot CH3OH, [Fe(eta(5)-C5H4-C5H4N)(eta(5)-C5H4C5H4NH)][HOOC(CH2)(2)COO]center dot[HOOC(CH2)(2)COOH], [Fe(eta(5)-C5H4-C(5)H4N)(2)]center dot [HOOC(CH2)(11)COOH]center dot 2CH(3)OH, [Fe(eta(5)-C5H4-C5H4N)(2)]center dot[HOOC(C6H4)COOH], [Fe(eta(5)-C5H4-C5H4NH)(2)][C6H3(COOH)(2)(COO)](2) and 3{[Fe(eta(5)-C5H4-C5H4N)(eta(5)-C5H4C5H4NH)][HOOC(SC4H2)COO]}center dot[Fe(eta(5)-C5H4-C5H4N)(2)]center dot 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(eta(5)-C5H4-C5H4NH)(2)][HOOC(CH)(2)COO](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.