From monomers to solids: Controlled hydrolysis to form novel, heteroleptic hydroxide-containing complexes

Four novel alkaline earth metal tetranuclear aryloxide/pyrazolate hydroxides of the general formula M₄(ligand)₆-(OH) ₂(donor)_n have been prepared by either adding stoichiometric quantities of water to preformed alkaline earth metal aryloxides or in a direct metalation regime combining metal, ligand (alcohol, pyrazole), and donor with stoichiometric amounts of water. The compounds are considered as potential intermediates in the sol-gel process. A nonhydrolyzable magnesium aryloxide has also been obtained using the same reaction scheme. Unexpectedly, a dimeric strontium complex with further association of a second dimer via hydrogen bonding from the solvent of crystallization, ethylenediamine, has been isolated by the treatment of strontium metal with a mixture of alcohol and water. All compounds were characterized using X-ray crystallography, ¹H and ¹³C NMR, and IR spectroscopy.