Abstract: Compounds of the formula(R.sup.11 Re).sub.k O.sub.1 R.sup.12 .sub.m .multidot.L.sub.n (III)in whichR.sup.11 is a hydrocarbon group which is bonded to the rhenium via a carbon atom to which at least one hydrogen atom is still attached,R.sup.12 is aliphatic hydrocarbon radical which may contain silicon bridge atoms, or is an unsubstituted or substituted phenyl radical,L is a ligand which is bonded to the rhenium metal via one to three oxygen and/or nitrogen atoms, and theindex k is 1 or 2, the index 1 is an integer from 1 to three times k, the index m is zero or an integer from 1 to twice k, and the index n is an integer from 1 to three times k, and in which the indices k, l, m and n are selected such that their combination satisfies the 5-, 6- or 7-valence of rhenium.The invention also provides compounds of the formula(polymer).sub.f .multidot.(CH.sub.3 ReO.sub.3).sub.8 (VI)in which the rhenium compound CH.sub.3 ReO.sub.3 is bonded to the polymer via amine or amide nitrogen in the polymer.