Metal complexes with heterocycles carbenes

A metal complex of the formula

• ›L.sub.a M.sub.b X.sub.c !.sup.n (A).sub.n I
• wherein M is ion of oxidation state of 1 to 8 of metals of groups 8, 9 and 10 of the periodic table as central atom, X is uni- or multidentate charged or uncharged ligands bound to the central atom, and L are ligands similarly bound to the central atom M, selected from the group consisting of monocarbenes of the formulae ##STR16## or dicarbenes of the formulae ##STR17## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are individually selected from the group consisting of optionally sulfonated alkyl of 1 to 7 carbon atoms, optionally sulfonated aliphatic mono- or poly-cyclics of 5 to 18 carbon atoms, optionally sulfonated alkenyl of 2 to 5 carbon atoms, optionally sulfonated aryl of 6 to 14 carbon atoms and optionally sulfonated arylalkyl of 7 to 19 carbon atoms, or R.sup.3, R.sup.4, R.sup.5 and R.sup.6 also can be hydrogen, or R.sup.3 and R.sup.4 together and R.sup.5 and R.sup.6 together in each case with the carbon atoms to which they are attached individually form fused and optionally sulfonated groups of 3 to 7 carbon atoms, Y is an optionally unsaturated alkylidene of 1 to 4 carbon atoms or a dialkylsilylene or a tetraalkyldisilylene, A is a singly charged anion or the chemical equivalent of a multiply charged anion, b is an integer from 1 to 3, a is an integer from 1 to 5.times.b and c=0 or an integer from 1 to 4.times.b, n=0 or an integer from 1 to 6, and c+n>0, but not (N,N'-dimethyl-benzimidazolin-2-ylidene)-chloro-(1,5-cyclooctadiene)-rhodi um.