Ruthenium-based complexes according to general formula wherein X 1 represents an anionic ligand; Y is O or S, preferably S; R 1 is C 6 -C 14 -aryl, an N-heterocyclic carbene ligand or P(R') 3 with R' being identical or different and representing either straight chain or branched C 1 -C 14 alkyl, C 6 -C 24 aryl, or C 3 -C 20 cycloalkyl; R means straight chain or branched C 1 -C 14 -alkyl; L 1 is an N-heterocyclic carbene ligand which is different from general structures (Ia*), (Ib*), (Ic*), and (Id*) defined below for L 2; L 2 means a ligand having the general structure (Ia*) or (Ib*) or a ligand having the general structure (Ic*) or (Id*) in which formulae (Ia*), (Ib*), (Ic*) and (Id*) n is identical or different and represents an integer in the range of from 1 to 20, D is identical or different and represents hydroxy, alkoxy, aryloxy, thiol, thiolate, thioether, selenol, selenoether, amine, phosphine, phosphate, phosphite, arsine, sulfoxide, sulfone, alkyl, phosphinimine, aminophosphine, carbene, selenoxide, imidazoline, imidazolidine, phosphine oxide, phosphine sulfide, phosphine selenide, ketone, ester, pyridyl, or any moiety able of acting as a two electron donor; R 3 is identical or different and represents H, alkyl or aryl; E is identical or different and represents a divalent moiety able of acting as a two electron donor selected from the group consisting of -O-, -S-, -Se-,-N -, -P -, -As -, -S(=O)-. -PR(=S)-, -PR(=O)-, -C(=O)-, -C(=S)-, 2,6-pyridylene and any other divalent moiety able of acting as a two electron donor; and R 2 are identical or different in a respective moiety (Ia*), (Ib*), (Ic*) or (Id*) and represent H, alkyl, aryl, halide, preferably chloride, or in the alternative two R 2 together with the two adjacent carbon atoms to which they are bound in a moiety (Ia*), (Ib*), (Ic*) or (Id*) form a fused-on five- or six-membered saturated or unsaturated ring. X 1 represents an anionic ligand; Y is O or S, preferably S; R 1 is C 6 -C 14 -aryl, an N-heterocyclic carbene ligand or P(R') 3 with R' being identical or different and representing either straight chain or branched C 1 -C 14 alkyl, C 6 -C 24 aryl, or C 3 -C 20 cycloalkyl; R means straight chain or branched C 1 -C 14 -alkyl; L 1 is an N-heterocyclic carbene ligand which is different from general structures (Ia*), (Ib*), (Ic*), and (Id*) defined below for L 2; L 2 means a ligand having the general structure (Ia*) or (Ib*) or a ligand having the general structure (Ic*) or (Id*) in which formulae (Ia*), (Ib*), (Ic*) and (Id*) n is identical or different and represents an integer in the range of from 1 to 20, D is identical or different and represents hydroxy, alkoxy, aryloxy, thiol, thiolate, thioether, selenol, selenoether, amine, phosphine, phosphate, phosphite, arsine, sulfoxide, sulfone, alkyl, phosphinimine, aminophosphine, carbene, selenoxide, imidazoline, imidazolidine, phosphine oxide, phosphine sulfide, phosphine selenide, ketone, ester, pyridyl, or any moiety able of acting as a two electron donor; R 3 is identical or different and represents H, alkyl or aryl; E is identical or different and represents a divalent moiety able of acting as a two electron donor selected from the group consisting of -O-, -S-, -Se-,-N -, -P -, -As -, -S(=O)-. -PR(=S)-, -PR(=O)-, -C(=O)-, -C(=S)-, 2,6-pyridylene and any other divalent moiety able of acting as a two electron donor; and R 2 are identical or different in a respective moiety (Ia*), (Ib*), (Ic*) or (Id*) and represent H, alkyl, aryl, halide, preferably chloride, or in the alternative two R 2 together with the two adjacent carbon atoms to which they are bound in a moiety (Ia*), (Ib*), (Ic*) or (Id*) form a fused-on five- or six-membered saturated or unsaturated ring. n is identical or different and represents an integer in the range of from 1 to 20, D is identical or different and represents hydroxy, alkoxy, aryloxy, thiol, thiolate, thioether, selenol, selenoether, amine, phosphine, phosphate, phosphite, arsine, sulfoxide, sulfone, alkyl, phosphinimine, aminophosphine, carbene, selenoxide, imidazoline, imidazolidine, phosphine oxide, phosphine sulfide, phosphine selenide, ketone, ester, pyridyl, or any moiety able of acting as a two electron donor; R 3 is identical or different and represents H, alkyl or aryl; E is identical or different and represents a divalent moiety able of acting as a two electron donor selected from the group consisting of -O-, -S-, -Se-,-N -, -P -, -As -, -S(=O)-. -PR(=S)-, -PR(=O)-, -C(=O)-, -C(=S)-, 2,6-pyridylene and any other divalent moiety able of acting as a two electron donor; and R 2 are identical or different in a respective moiety (Ia*), (Ib*), (Ic*) or (Id*) and represent H, alkyl, aryl, halide, preferably chloride, or in the alternative two R 2 together with the two adjacent carbon atoms to which they are bound in a moiety (Ia*), (Ib*), (Ic*) or (Id*) form a fused-on five- or six-membered saturated or unsaturated ring.