A metal-carbene complex of the general formula in which the variables are each defined as follows: R 1 is independently hydrogen, a linear or branched alkyl radical which has 1 to 20 carbon atoms, is optionally interrupted by at least one heteroatom and optionally bears at least one functional group, a cycloalkyl radical which has 3 to 20 carbon atoms, is optionally interrupted by at least one heteroatom and optionally bears at least one functional group, a substituted or unsubstituted aryl radical which has 6 to 30 carbon atoms and optionally bears at least one functional group, a substituted or unsubstituted heteroaryl radical which has a total of 5 to 18 carbon atoms and heteroatoms and optionally bears at least one functional group, or the two R 1 radicals, together with the carbon atom to which they are bonded, are a substituted or unsubstituted C 5, C 6, C 7 or C 8 ring, R 5 and R 6 together, or R 6 and R 7 together, form a unit of the formula: in which * denotes the connection to the carbon atoms of the benzene ring bearing the R 5 and R 6 radicals or R 6 and R 7 radicals, and the oxygen atom is connected to the carbon atom bearing the R 5, R 6 or R 7 radical, A is oxygen or sulfur, R 2 is a linear or branched alkyl radical which has 1 to 20 carbon atoms, is optionally interrupted by at least one heteroatom and optionally bears at least one functional group, a cycloalkyl radical which has 3 to 20 carbon atoms, is optionally interrupted by at least one heteroatom and optionally bears at least one functional group, a substituted or unsubstituted aryl radical which has 6 to 30 carbon atoms and optionally bears at least one functional group, a substituted or unsubstituted heteroaryl radical which has a total of 5 to 18 carbon atoms and/or heteroatoms and optionally bears at least one functional group, R 3, R 4 are each independently a linear or branched alkyl radical which has 1 to 20 carbon atoms, is optionally interrupted by at least one heteroatom and optionally bears at least one functional group, a cycloalkyl radical which has 3 to 20 carbon atoms, is optionally interrupted by at least one heteroatom and optionally bears at least one functional group, a substituted or unsubstituted aryl radical which has 6 to 30 carbon atoms and optionally bears at least one functional group, a substituted or unsubstituted heteroaryl radical which has a total of 5 to 18 carbon atoms and/or heteroatoms and optionally bears at least one functional group, R 8 is a linear or branched alkyl radical having 1 to 4 carbon atoms, m, n are each independently 0, 1, 2 or 3. R 1 is independently hydrogen, a linear or branched alkyl radical which has 1 to 20 carbon atoms, is optionally interrupted by at least one heteroatom and optionally bears at least one functional group, a cycloalkyl radical which has 3 to 20 carbon atoms, is optionally interrupted by at least one heteroatom and optionally bears at least one functional group, a substituted or unsubstituted aryl radical which has 6 to 30 carbon atoms and optionally bears at least one functional group, a substituted or unsubstituted heteroaryl radical which has a total of 5 to 18 carbon atoms and heteroatoms and optionally bears at least one functional group, or the two R 1 radicals, together with the carbon atom to which they are bonded, are a substituted or unsubstituted C 5, C 6, C 7 or C 8 ring, R 5 and R 6 together, or R 6 and R 7 together, form a unit of the formula: in which * denotes the connection to the carbon atoms of the benzene ring bearing the R 5 and R 6 radicals or R 6 and R 7 radicals, and the oxygen atom is connected to the carbon atom bearing the R 5, R 6 or R 7 radical, A is oxygen or sulfur, R 2 is a linear or branched alkyl radical which has 1 to 20 carbon atoms, is optionally interrupted by at least one heteroatom and optionally bears at least one functional group, a cycloalkyl radical which has 3 to 20 carbon atoms, is optionally interrupted by at least one heteroatom and optionally bears at least one functional group, a substituted or unsubstituted aryl radical which has 6 to 30 carbon atoms and optionally bears at least one functional group, a substituted or unsubstituted heteroaryl radical which has a total of 5 to 18 carbon atoms and/or heteroatoms and optionally bears at least one functional group, R 3, R 4 are each independently a linear or branched alkyl radical which has 1 to 20 carbon atoms, is optionally interrupted by at least one heteroatom and optionally bears at least one functional group, a cycloalkyl radical which has 3 to 20 carbon atoms, is optionally interrupted by at least one heteroatom and optionally bears at least one functional group, a substituted or unsubstituted aryl radical which has 6 to 30 carbon atoms and optionally bears at least one functional group, a substituted or unsubstituted heteroaryl radical which has a total of 5 to 18 carbon atoms and/or heteroatoms and optionally bears at least one functional group, R 8 is a linear or branched alkyl radical having 1 to 4 carbon atoms, m, n are each independently 0, 1, 2 or 3.