The Utilisation of Solvent-Free Synthesis for the Reaction of Cobalt with Imidazole: MOF Conversion from 3∞[Co3(Im)6(ImH)2] via 3∞[Co4(Im)8(ImH)] to 3∞[Co(Im)2]

The redox potential of cobalt metal proves sufficient to oxidise the metal with a melt of imidazole. Depending on the temperature of the organic melt different three-dimensional cobalt imidazolate frameworks and hydrogen form. The initial product is (3)(infinity)[Co-3(Im)(6)(ImH)(2)], which transforms under release of imidazole at 210 degrees C into (3)(infinity)[Co-4(Im)(8)(ImH)]. The latter releases the remaining imidazole at temperatures >225 degrees C and forms homoleptic (3)(infinity)[Co(Im)(2)], which is thermally stable up to 550 degrees C. Thereby, a direct reaction route starting from the metal was established that prevents the use of toxic and sensitive metallocenes.