Abstract
The phosphonate-substituted zirconium oxo clusters Zr6O2(OBu)12(O3PPh)4 and Zr7O2(OiPr)12(O3PCH2CH2CH2Br)6, with octahedrally coordinated Zr atoms, were synthesized by reaction of zirconium alkoxides with phosphonic acid bis(trimethylsilyl) esters. The basic structural motif are Zr3O(µ2-OR)3(OR)3 units which are connected in different ways.