Bicyclic compounds of the formula I in which A1 or A5 is C and the other of the two variables A1, A5 is N, C or C—R3; A2, A3, A4 independently of one another are N or C—R3a, where one of the variables A2, A3 or A4 may also be S or a group N—R4 if A1 and A5 are both C, and where A4 is not N or C—R3a if A1 is N, A3 is C—R3a and A5 is C, and where A1 is attached to A2 and A3 to A4 or A2 is attached to A3 and A4 to A5 or A1 is attached to A5 and A2 to A3 or A1 is attached to A5 and A3 to A4 or A1 is attached to A2 and A4 to A5 by double bonds; n is 0, 1, 2, 3, 4 or 5; Ra is halogen, cyano, C1-C6-alkyl, C1-C6-alkoxy, C1-C6-haloalkyl, C1-C6-haloalkoxy, C2-C6-alkenyl, C2-C6-alkenyloxy or C(O)R5; R1 is halogen, cyano, C1-C10-alkyl, where a carbon atom of the C1-C10-alkyl radical may be replaced by a silicium atom, C1-C6-haloalkyl, C2-C10-alkenyl, C2-C6-haloalkenyl, C2-C6-alkynyl, C3-C8-cycloalkyl, C3-C8-cycloalkyl-C1-C4-alkyl, where the cycloalkyl moiety of the two last-mentioned groups may be unsubstituted or contain 1, 2, 3, 4, 5, or 6 radicals selected from the group consisting of C1-C4-alkylidene, C1-C4-alkyl, halogen, C1-C4-haloalkyl and hydroxy and the alkyl moiety of C3-C8-cycloalkyl-C1-C4-alkyl may be unsubstituted or contain 1, 2, 3, or 4 radicals selected from the group consisting of halogen, C1-C4-haloalkyl and hydroxy, C5-C8-cycloalkenyl which may be unsubstituted or contain 1, 2, 3 or 4 radicals selected from the group consisting of C1-C4-alkyl, halogen, C1-C4-haloalkyl and hydroxy, OR6, SR6, NR7R8, a radical of the formula —C(R11)(R12)C(═NOR13)(R14) or a radical of the formula —C(═NOR15)C(═NOR16)(R17); R2 is halogen, cyano, C1-C6-alkyl, C1-C6-haloalkyl, C2-C6-alkenyl, C2-C6-haloalkenyl, C2-C6-alkynyl, C3-C8-cycloalkyl, C5-C8-cycloalkenyl, OR6, SR6 or NR7R8; and the agriculturally acceptable salts of the compounds I, crop protection compositions comprising at least one compound of the formula I and/or an agriculturally acceptable salt of I and at least one solid or liquid carrier and a method for controlling phytopathogenic harmful fungi are described.