A metal-carbene complex of the general formula wherein M is Pd or Pt, m is an integer selected from 0 or 1, R 1 and R 1 ' are each independently a linear or branched alkyl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 3 to 20 carbon atoms, substituted or unsubstituted aryl radical, optionally bearing at least one functional group and having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having a total of 5 to 18 carbon atoms and/or heteroatoms; R 2, R 2 ', R 3 and R 3 ' are each independently hydrogen, a linear or branched alkyl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 3 to 20 carbon atoms, substituted or unsubstituted aryl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having a total of 5 to 18 carbon atoms and/or heteroatoms, or a group with donor or acceptor action, or R 1 and R 2 and/or R 1 ' and R 2 ' together with the atoms to which they are bonded form an optionally substituted, saturated or unsaturated or aromatic ring optionally interrupted by at least one further heteroatom and having a total of 5 to 18 carbon atoms and/or heteroatoms, and may optionally be fused to at least one further optionally substituted saturated or unsaturated or aromatic ring optionally interrupted by at least one further heteroatom and having a total of 5 to 18 carbon atoms and/or heteroatoms; K is a neutral monodentate ligand, L is a monoanionic ligand, which can be mono- or bidentate. M is Pd or Pt, m is an integer selected from 0 or 1, R 1 and R 1 ' are each independently a linear or branched alkyl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 3 to 20 carbon atoms, substituted or unsubstituted aryl radical, optionally bearing at least one functional group and having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having a total of 5 to 18 carbon atoms and/or heteroatoms; R 2, R 2 ', R 3 and R 3 ' are each independently hydrogen, a linear or branched alkyl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 3 to 20 carbon atoms, substituted or unsubstituted aryl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having a total of 5 to 18 carbon atoms and/or heteroatoms, or a group with donor or acceptor action, or R 1 and R 2 and/or R 1 ' and R 2 ' together with the atoms to which they are bonded form an optionally substituted, saturated or unsaturated or aromatic ring optionally interrupted by at least one further heteroatom and having a total of 5 to 18 carbon atoms and/or heteroatoms, and may optionally be fused to at least one further optionally substituted saturated or unsaturated or aromatic ring optionally interrupted by at least one further heteroatom and having a total of 5 to 18 carbon atoms and/or heteroatoms; K is a neutral monodentate ligand, L is a monoanionic ligand, which can be mono- or bidentate.