The present invention relates to compounds of the formula (I), in particular to phenylamidines of the formula (I), to a process for their preparation, to the use of phenylamidines of the formula (I) according to the invention for controlling unwanted microorganisms, in particular phytopathogenic fungi and also to a composition for this purpose, comprising the phenylamidines of the formula (I) according to the invention. Furthermore, the invention relates to a method for controlling unwanted microorganisms, in particular phytopathogenic fungi, characterized in that the compounds of the formula (I) are applied to the microorganisms, in particular to the phytopathogenic fungi and/or in their habitat.