Organometallic crystals engineering Part 7. Construction of mixed-metal crystalline systems via electrostatic interactions and cooperative strong and weak hydrogen bonds

摘要

The dicarboxylic organometallic acid [#eta#~5-C_5H_4COOH)_2Fe] (FeACH_2) has been used to produce to produce a series of novel mixed-metal mixed-valent crystalline materials by the sequence of reaction step: (i) oxidation in the air of THF solutions of [(#eta#~5-C_2H_5)_2Co] and [(#eta#~6-C_6H_6)_2Cr] and consequent reduction of O_2 to the strongly basic anion O_2~-; (ii) deprotonation of FeACH_2 to yield the anion FeACH~- (or FEAC~2); (iii) precipitation of the insoluble organometallic salts formed between the organometallic acidate and the diamagnetic cation [(#eta#~5-C_5H_5)_2Co]~+ or the paramagnetic cation [(#eta#~6-C_6H_6)_2Cr]~+. The novel materials [(#eta#~5-C_5H_5)_2Co]~+ [(#eta#~5-C_5H_4COOH)(#eta#~5-C_5H_4COO)Fe] (1), [(#eta#~5-C_5H_5)_2Co]~+[(#eta#~5-C_5H_4COOH)(#eta#~5-C_5H_4COO)Fe]. H_2O (2), {[#eta#~6-C_6H_6)_2Cr]~+}_(2-) {[(#eta#~5-C_5H_4COOH)(#eta#~5-C_5H_4COOH)_2Fe]}~(2-) (3) and [(#eta#~6-C_6H_6)_2Cr]~+ {[(#eta#~5-C_5H_4COOH)(#eta~5-C_5H_4COOH)(#eta~5-C_5H_4COO)-Fe}~-. H_2O (4) have been prepared and structurally characterised by low temperature single-crystal X-ray diffraction. The four species contain different electronic and spin metal centres: 18 electrons Fe~(II) and Co~(III) are present in 1 and 2 whereas Fe~(II) an paramagnetic 17 electrons Cr~1 are present in 3 and 4. The crystalline edifices are held together by the complementary contribution of neutral O-H...O and/or negatively charged O-H...O~(-) hydrogen bonding interactions between the acid moieties and of charge assisted C-H~δ+...O~δ- bonds between cations and anions. The structure of the heavily hydrated' species [{(#eta#~5-C_5H_5)_2Co]~+}_2[(#eta#~5-C_5H_4COO)_2Fe]~(2-). 7.75 H_2O (5), in which the acid is completely deprotaonated, will also be discussed.