. . . "R7 is ##STR4## in which R11, R12 and R13 are identical or different and are a hydrogen atom, a halogen atom, a C1 -C10 -, preferably C1 -C4 -alkyl group, in particular a methyl group, a C1 -C10 -fluoroalkyl group, preferably a CF3 -- group, a C6 -C10 -, preferably C6 -C8 -aryl group, a C6 -C10 -fluoroaryl group, preferably a pentafluorophenyl group, a C1 -C10 -, preferably C1 -C4 -alkoxy group, in" . . . . . .