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

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)] and [(AgBr)₂(n-pica)] to be obtained, and we report the new structures of [(AgBr)₂(3-pica)] and [(AgBr)₂(4-pica)] 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)]/[(AgBr)₂(n-pica)] by mechanochemical and thermal properties. The in situ experiments suggest that [(AgBr)(3-pica)] is kinetically favoured while [(AgBr)₂(3-pica)] is converted into [(AgBr)(3-pica)] 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.