Molecular oxo-hydroxo clusters have been synthesized by reactions of arylstibonic acids with organophosphonic acid and phenylseleninic acid. Single crystal X-ray structural elucidation revealed the formation of [(p-i-PrC6H4Sb)4(OH)4(t-BuPO3)6] (1), [(p-t-BuC6H4Sb)4(O)2(PhPO3)4(PhPO3H)4] (2), [(p-i-PrC6H4Sb)4(O)3(OH)(PhSeO2)2(t-BuPO3)4(t-BuPO3H2)2] (3), [(p-MeC6H4Sb)4(O)3(OH)(PhSeO2)2(t-BuPO3)4(t-BuPO3H2)2] (4) and [(p-t-BuC6H4Sb)2(O) (PhSeO2)2(t-BuPO3H)4] (5) respectively. Mass spectral studies reveal that the clusters maintain their structural integrity in solution as well. Solution NMR studies ((1)H, (31)P and (77)Se) show spectral patterns which correlate well with the observed solid state structures of 1-5.

Isolation and structural characterization of novel organoantimony­(V)-based oxo clusters are reported. (RSb)4(OH)4(t-BuPO3)6 and (RSb)2(O)­(t-BuPO3H)6 independently in the presence of pyridine under solvothermal conditions afford the hexanuclear organoantimonate clusters [(RSb)6(μ3-O)2(μ2-O)6(t-BuPO3)4], where R = p-i-PrC6H4 (1), p-ClC6H4 (2). Further, reaction of organostibonate phosphonate with Ti­(O i Pr)4 in the presence of pyridine under solvothermal conditions afforded the mixed-metal titanium stibonate hexanuclear clusters [(RSb)2Ti4(μ3-O)2(μ2-O)2(t-BuPO3)4(μ-OCH3)4(OCH3)4], where R = p-i-PrC6H4 (3), p-ClC6H4 (4). Band gap measurements were performed on 1–4. They reveal a remarkable reduction in the band gap on moving from the heavier main-group-based oxo cages (1 and 2) to the titanium-incorporated oxo cages (3 and 4).

The reaction of RSbO3H2 with t-butylsilanetriol has led to the isolation of organoantimony(v) based molecular triangles stabilized by siloxane frameworks. Depending on the reaction conditions employed or the substituents present on the antimony atom, either a combination of a disiloxane and a tetrasiloxane framework or a trisiloxane framework was generated in situ leading to the stabilization of the Sb3 triangle.