Liquid reagents are not enough for liquid assisted grinding in the synthesis of [(AgBr)(n-pica)]_n

This study investigates the mechanochemical reactions between AgBr 3-picolylamine and 4-picolylamine. The use of different stoichiometry ratios of the reagents allows [(AgBr)(n-pica)](n) and [(AgBr)(2)(n-pica)](n) to be obtained, and we report the new structures of [(AgBr)(2)(3-pica)](n) and [(AgBr)(2)(4-pica)](n) which are characterized by the presence of the following: (a) infinite inorganic chains, (b) silver atom coordinated only by bromide atoms and (c) argentophilic interactions. Furthermore, we studied the interconversion of [(AgBr)(n-pica)](n)/[(AgBr)(2)(n-pica)](n) by mechanochemical and thermal properties. The in situ experiments suggest that [(AgBr)(3-pica)](n) is kinetically favoured while [(AgBr)(2)(3-pica)](n) is converted into [(AgBr)(3-pica)](n) only with a high excess of the ligand. Finally, the liquid nature of the ligands is not sufficient to assist the grinding process, and the complete reaction is observed with the addition of a small quantity of acetonitrile.