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)(mu(3)-O)(2)(mu(2)-O)(6)(t-BuPO3)(4)], where R = p-i-PrC6H4 (1), p-CIC6H4 (2). Further, reaction of organostibonate phosphonate with Ti(O'Pr)(4) in the presence of pyridine under solvothermal conditions afforded the mixed-metal titanium stibonate hexanuclear clusters [(RSb)(2)Ti-4(mu(3)-O)(2)(mu(2)-O)(2)(t-BuPO3)(4)(mu-OCH3)(4)(OCH3)(4)], where R = p-i-PrC6H4 (3), p-CIC6H4 (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).