Use of metal complex compounds of formula (1) [LnMcmXp]zYq wherein Mc is manganese, titanium, iron, cobalt, nickel or copper, X is a coordinating or bridging radical, n and m are each independently of the other an integer having a value of from 1 to 8, p is an integer having a value of from 0 to 32, z is the charge of the metal complex, Y is a counter-ion, q=z/(charge Y), and L is a ligand of formula (2) wherein R1, R2, R3, R4, R5, R6, R7, R8, R9, R10 and R11 are each independently of the others hydrogen: unsubstituted or substituted C1-C18alkyl or aryl; cyano; halogen; nitro; —COOR12 or —SO3R12 wherein R12 is in each case hydrogen, a cation or unsubstituted or substituted C1-C18alkyl or aryl: —SR13, —SO12R13 or —OR13 wherein R13 is in each case hydrogen or unsubstituted or substituted C1-C18alkyl or aryl; —NR14R15; —(C1-C6alkylene)-NR14R15; —NoR14R15R16; —(C1-C6alkylene)-NoR14R15R16; —N(R)15)—(C1-C6alkylene)-NR1R15; —N[(C1-C6alkylene)-NR14R15]2; —N(R13)—(C1-C6alkylene)-NoR14R15R16, —N[C1-C6alkylene)-NoR14R15R16]2; —N(R13)—N—R14R15 or —N(R13)—NoR14R15R16: wherein R13 is as defined above and R14, R15 and R16 are each independently of the other(s) hydrogen or unsubstituted or substituted C1-C18alkyl or aryl, or R14 and R15 together with the nitrogen atom bonding them form an unsubstituted or substituted 5-, 6- or 7-membered ring which may optionally contain further heterotatoms; with the proviso that (i) at least one of the substituents R1—R11 contains a quaternized atom which is not directly bonded to one of the three pyridine A, B or C and that (ii) Y is neither I′ nor Cl′ in the case that Me is Mn(II), R1—R5 and R7—R11 are hydrogen and R6 is formula (III) as catalysts for oxidation reactions, and the novel metal complex compounds of formula (1), the novel ligands of formula (2) and their starting materials.