Metal containing new inorganic ring systems based on siloxane and phosphazane frameworks

Abstract

High-Field P-31 NMR spectroscopy and single crystal X-ray diffraction studies have been used to study the ring opening and nucleophilic substitution reactions of the lambda (3)-cyclotriphosphazane [EtNPCl](3). The synthesis of the ring opened silicophosphonate [RSi(OH){OP(O)(H)(OH)}](2)O (R=(2,6-iPr(2)C(6)H(3))NSiMe3) (1) represents the first ever molecular silicophosphonate to be isolated bearing free reactive hydroxyl groups. The structure and conformation of the bulky aryloxide substituted lambda (3)-cyclotriphosphazane derivative [EtNP(OAr)](3) (Ar = 2,6-iPr(2)C(6)H(3)) (2) has also been investigated. Interaction of 2 with transition metal precursor complexes leads to the isolation of phosphazane metal complexes with different mode of co-ordination of 2. Further, the reaction of Cp*Ti(OAr)Cl-2 (Ar = 2,6-(CH3)(2)C6H3H) with O{SiPh2(OH)}(2) gave the eight-membered trititanosiloxane [Cp*Ti(Cl) (O(SiPh2O)(2)SiPh2O) (3). Siloxane chain expansion effects, presumed to be a consequence of ring strain, have been observed in the product. The presence of reactive Ti-Cl bond in 3 offers opportunities for its reaction chemistry to be explored.