Novel Organic-Soluble Molecular Titanophosphonates with Cage Structures Comparable to Titanium-Containing Silicates

Reactions of Cp*TiMe3 (Cp* = C5Me5) with methyl-, phenyl- and tert-butylphosphonic acids [RP(O)(OH)2] (R = Me, Ph, t-Bu) yield the air-stable titanophosphonates [(Cp*TiO3PR)4(μ-O)2] (R = Me (1), Ph (2)) and [(Cp*Ti)3(t-BuPO3)2{t-BuPO2(OH)}(μ-O)2] (3), which are freely soluble in organic solvents. Alternatively, the reaction between Cp*TiCl3 and methylphosphonic acid was also found to produce 1. The titanophosphonates mentioned are the first examples of organic-soluble molecular transition metal phosphonate cages.