Compounds of formula wherein X is N or P; -SO 3 - is -O-S 2 - or -S 2 -O-; R 3 is C 1 -C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 10 alkynyl, C 6 -C 12 aryl or C 7 -C 24 aralkyl, which may be substituted by one or more groups selected from F, cyclopropyl, 1,2-epoxyethyl, and sulfonate, and wherein one or more CH 2 groups of alkyl, alkenyl, alkynyl and aralkyl which are not directly bound to the X-atom may be replaced by O, 1,2-epoxyethylene, cyclopropylene or SO 3; R 1 and R 2 are linked and jointly selected from -(CH 2) m - alkylene with m = 4 or 5 forming together with the central X-atom a five- or six-membered heterocycle wherein one or more H of -(CH 2) m - alkylene may be substituted by one or more substituents selected from F and optionally fluorinated C 1 -C 10 alkyl, and wherein one or more CH 2 groups of -(CH 2) m - alkylene may be replaced by O, S or NR'; R' is selected from C 1 -C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 10 alkynyl, C 6 -C 12 aryl, and C 7 -C 24 aralkyl, which may be substituted one or more groups selected from F, cyclopropyl, 1,2-epoxyethyl, and sulfonate, and wherein one or more CH 2 groups of alkyl, alkenyl, alkynyl and aralkyl which are not directly bound to the N-atom may be replaced by O, 1,2-epoxyethylene, cyclopropylene or SO 3; n is an integer from 1 to 8 and wherein one or more CH 2 groups of the -(CH 2) n - alkylene chain which are not directly bound to the X-atom or the SO 3 group may be replaced by O and wherein two adjacent CH 2 groups of the -(CH 2) n - alkylene chain may be replaced by a C-C double bond or a C-C triple bond; R 4 is selected from C 1 -C 6 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, C 6 -C 12 aryl, and C 7 -C 24 aralkyl, which may be substituted one or more groups selected from F, cyclopropyl, 1,2-epoxyethyl, and sulfonate, and wherein one or more CH 2 groups of alkyl, alkenyl, alkynyl and aralkyl which are not directly bound to the SO 3 group may be replaced by O, 1,2-epoxyethylene, cyclopropylene or SO 3; R 5 is selected from C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, C 6 -C 12 aryl, and C 7 -C 24 aralkyl, wherein alkyl, alkenyl, alkynyl and aralkyl may be substituted by a group selected from cyclopropyl and 1,2-epoxyethyl, and wherein one or more CH 2 groups of alkyl, alkenyl, alkynyl and aralkyl which are not directly bound to the SO 3 group may be replaced by one or more groups selected from O, 1,2-epoxyethylene, cyclopropylene, SO 3, and NR"; and R" is selected from C 1 -C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 10 alkynyl, C 6 -C 12 aryl, and C 7 -C 24 aralkyl, which be substituted by one or more groups selected from 1,2-epoxyethyl, cyclopropyl, and sulfonate, and wherein one or more CH 2 group of alkyl, alkenyl, alkynyl, and aralkyl, which are not directly bound to the N-atom may be replaced by O, 1,2-epoxyethylene, cyclopropylene or SO 3. X is N or P; -SO 3 - is -O-S 2 - or -S 2 -O-; R 3 is C 1 -C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 10 alkynyl, C 6 -C 12 aryl or C 7 -C 24 aralkyl, which may be substituted by one or more groups selected from F, cyclopropyl, 1,2-epoxyethyl, and sulfonate, and wherein one or more CH 2 groups of alkyl, alkenyl, alkynyl and aralkyl which are not directly bound to the X-atom may be replaced by O, 1,2-epoxyethylene, cyclopropylene or SO 3; R 1 and R 2 are linked and jointly selected from -(CH 2) m - alkylene with m = 4 or 5 forming together with the central X-atom a five- or six-membered heterocycle wherein one or more H of -(CH 2) m - alkylene may be substituted by one or more substituents selected from F and optionally fluorinated C 1 -C 10 alkyl, and wherein one or more CH 2 groups of -(CH 2) m - alkylene may be replaced by O, S or NR'; R' is selected from C 1 -C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 10 alkynyl, C 6 -C 12 aryl, and C 7 -C 24 aralkyl, which may be substituted one or more groups selected from F, cyclopropyl, 1,2-epoxyethyl, and sulfonate, and wherein one or more CH 2 groups of alkyl, alkenyl, alkynyl and aralkyl which are not directly bound to the N-atom may be replaced by O, 1,2-epoxyethylene, cyclopropylene or SO 3; n is an integer from 1 to 8 and wherein one or more CH 2 groups of the -(CH 2) n - alkylene chain which are not directly bound to the X-atom or the SO 3 group may be replaced by O and wherein two adjacent CH 2 groups of the -(CH 2) n - alkylene chain may be replaced by a C-C double bond or a C-C triple bond; R 4 is selected from C 1 -C 6 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, C 6 -C 12 aryl, and C 7 -C 24 aralkyl, which may be substituted one or more groups selected from F, cyclopropyl, 1,2-epoxyethyl, and sulfonate, and wherein one or more CH 2 groups of alkyl, alkenyl, alkynyl and aralkyl which are not directly bound to the SO 3 group may be replaced by O, 1,2-epoxyethylene, cyclopropylene or SO 3; R 5 is selected from C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, C 6 -C 12 aryl, and C 7 -C 24 aralkyl, wherein alkyl, alkenyl, alkynyl and aralkyl may be substituted by a group selected from cyclopropyl and 1,2-epoxyethyl, and wherein one or more CH 2 groups of alkyl, alkenyl, alkynyl and aralkyl which are not directly bound to the SO 3 group may be replaced by one or more groups selected from O, 1,2-epoxyethylene, cyclopropylene, SO 3, and NR"; and R" is selected from C 1 -C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 10 alkynyl, C 6 -C 12 aryl, and C 7 -C 24 aralkyl, which be substituted by one or more groups selected from 1,2-epoxyethyl, cyclopropyl, and sulfonate, and wherein one or more CH 2 group of alkyl, alkenyl, alkynyl, and aralkyl, which are not directly bound to the N-atom may be replaced by O, 1,2-epoxyethylene, cyclopropylene or SO 3.