Use of metal complex compounds of formula (1): [L>n m p Yq wherein Me 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-C18 alkyl 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, -SO2R13 or -OR13 wherein R13 is in each case hydrogen or unsubstituted or substituted C1-C18alkyl or aryl;-N(R13)-NR'13R"13 wherein R13, R'13 and R"13 are as defined above for R13; -NR14R15 or -N R14R15R16 wherein 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 hetero atoms; with the proviso that R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, and R11 are not simultaneously hydrogen, as catalysts for oxidation reactions, and the novel metal complex compounds of formula (1) and the novel ligands of formula (2).