Isolation of Tetranuclear Organoantimony Oxo Clusters and Hexa-decanuclear Polyoxostibonates

Reaction of phenolic pyrazolyl ligands with arylstibonic acids afforded two novel tetranuclear clusters [(p-X-C6H4Sb)(4)(O)(5)(OH)(2)(HPhPzR(1))(4)] (where X = Cl, R-1 = Ph (1); X = Br, R-1 = Ph (2); X = Br, R-1 = t-Bu (3)) and [(p-Br-C6H4Sb)(4)(PhPz)(4)(O)(4)] (4). Depending on the steric bulk of the group present on the pyrazole ring, either one (1-3) or two (4) of the ring nitrogens have been found to coordinate to the metal atoms. Remarkably, when 3,5-DMPz is reacted with arylstibonic acid, hexa-decanuclear polyoxostibonates [(p-X-C6H4Sb)(16)(O)(28)(OH)(8)](3,5-DMPz)(6) (X = Cl (5), Br (6)) have been isolated.