The invention relates to new compounds of the formula, wherein R and R.sup.1 are each independently hydrogen, a linear or branched C.sub.1-40 alkyl, C.sub.2-40 alkenyl or C.sub.2-40 alkynyl group, an aryl or C.sub.1-40 alkylaryl group or an optionally complex metal ion M.sup.n+/n wherein n is an integer from 1 to 8; the free valences of the silicate oxygen atoms are saturated by one or more of: silicon atoms of other groups of the formula, hydrogen, a linear or branched C.sub.1-12 alkyl group or by cross-linking bridge members R.sup.3.sub.qM.sup.1(OR.sup.2).sub.mO.sub.k/2 or Al(OR.sup.2).sub.3-pO.sub.p/2 or R.sup.3 Al(OR.sup.-).sub.2-1 O.sub.1/2; wherein M.sup.1 is Si or Ti; R.sup.2 is linear or branched C.sub.1-12 alkyl group; and R.sup.3 is alinear or branched C.sub.1-6 alkyl group; k is an integer from 1 to 4 and q and m are integers from 0 to 2; such that M+k+q=4; and p is an integer from 1 to 3; and r is an integer from 1 to 2; or other known oxo metal bridging systems; x, y and z are integers such that the radio of x:y+z, varies from 0.00001 to 100,000 with the fragments [O.sub.3/2SiCH(CH.sub.2PO(OR)(OR.sup.1))CH.sub.2CH.sub.2SiO.sub- .3/2].sub.x and [O.sub.3/2SiCH.sub.2CH.sub.2PO(OR)(OR.sup.1)].sub.y always present whilst the integer z varies from 0 to 200y. The compounds are useful as catalysts for a wide variety of reactions and have the advantages that they can be prepared in a one-pot reaction and functional group losding can be tailored to be at a required level. In addition, the compounds have high chemical and thermal stability, fixed and rigid structures, are insoluble in organic solvents, high resistance to ageing, and can easily be purified and reused.