Reaction of (p-halophenyl)stibonic acid with diphenylsilanediol (in ratio 1:1) in refluxing toluene for 6 h afforded colorless crystalline products in high yields. Single-crystal X-ray structural elucidation reveals the formation of the products [(p-Cl-C6H4Sb)4(O)4(Ph2SiO2)4] (1) and [(p-Br-C6H4Sb)4(O)4(Ph2SiO2)4] (2), respectively. The clusters 1 and 2 were isostructural; the core consists of a distorted Sb4O4 cubane framework with the siloxides acting as bridging ligands across the antimony atoms present at alternate corners of the cube.

A series of tetranuclear lanthanide (Ln = Tb, Dy, Ho) hydroxo clusters has been synthesized by reaction of LnCl3·6H2O (Ln = Tb (1), Dy (2), Ho (3)) with o-vanilin based schiff base ligand 2-(2,3 dihydroxpropyl imino methyl) 6-methoxy phenol (H3L) in methanol and in the presence of triethylamine as base. The solid state structures of all the products were established by single crystal X-ray diffraction technique. Magnetism studies reveal that Dy4 analogue exhibits slow magnetic relaxation at low temperatures.

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.

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Depolymerization reactions of organostibonic acids with protic ligands have been investigated. Reaction of arylstibonic acids with 8-hydroxyquinoline (8-HQ), or {2-[1H-pyrazol-5(3)-yl]naphthalene-1-ol} (H(2)naphpz) in a 1 : 1 stoichiometry in refluxing toluene affords adamantane-like L(4)(RSb)(4)O(6) clusters [(p-XC(6)H(4)Sb)(4)(O)(6)(Q)(4)] (where X = Cl (1), Br (2), QH = 8-hydroxyquinoline), [(p-ClC(6)H(4)Sb)(4)(O)(6)(Hnaphpz)(4)]·H(2)naphpz (3) and [(p-Br-C(6)H(4)Sb)(4)(O)(6)(Hnaphpz)(4)](2)·H(2)naphpz (4). Further a tetrameric organoantimony oxo cluster, L(4)(RSb)(4)O(4) [(p-ClC(6)H(4)Sb)(4)(O)(4)(naphpz)(4)] (5) has also been isolated as a side product in the reaction of arylstibonic acid with naphthylphenolic pyrazole. Interestingly 1-4 structurally resemble the dimeric form of the antimony oxide Sb(2)O(3) and its mineral senarmontite.