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(HPhPzR1)4] (where X = Cl, R1 = Ph (1); X = Br, R1 = Ph (2); X = Br, R1 = 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.