Compound of the formula I-2 in which L 1 and L 2 both denote F, and each, independently of one another, and, if present more than once, also independently of one another, denote (a) a trans-1,4-cyclohexylene radical, in which, in addition, one or two non-adjacent CH 2 groups may be replaced by -O- and/or -S-, (b) (c) a 1,4-phenylene radical, in which, in addition, one or two non-adjacent CH groups may be replaced by N, or (d) a radical selected from the group 1,4-bicyclo[2.2.2]octylene, 1,3-bicyclo[1.1.1]pentylene, spiro[3.3]heptane-2,4-diyl, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl and 1,2,3,4-tetrahydronaphthalene-2,6-diyl, R 1 and R 2 each, independently of one another, denote H, halogen, -CN, -SCN, -SF 5, -CF 3, -CHF 2, -CH 2 F, -OCF 3, -OCHF 2, an alkyl group having 1 to 15 C atoms which is monosubstituted by CN or CF 3 or at least monosubstituted by halogen, where, in addition, one or more CH 2 groups may each, independently of one another, be replaced by -O-, -S-, -CH=CH-, -CF=CF-, -CF=CH-, -CH=CF-, -CO-, -CO-O-, -O-CO- or -O-CO-O- in such a way that neither O nor S atoms are linked directly to one another, or one of R 1 and R 2 denotes alkyl or alkoxy having 1 to 12 C atoms, alkoxyalkyl, alkenyl or alkenyloxy having 2 to 12 C atoms and the other, independently of the first, like-wise denotes alkyl or alkoxy having 1 to 12 C atoms, alkoxyalkyl, alkenyl or alkenyloxy having 2 to 12 C atoms or alternatively F, Cl, Br, -CN, -SCN, -SF 5, -CF 3, -CHF 2, -CH 2 F, -OCF 3 or -OCHF 2, Z 1 and Z 2 each, independently of one another, denote -CH2-CH2-, -CF 2 -CF 2 -, -CF2-CH2-, -CH 2 -CF 2 -, -CH=CH-, -CF=CF-, -CF=CH-, -CH=CF-, -C≡C-, -COO-, -OCO-, -OCH 2 -, -CH 2 O-, -CF 2 O-, -OCF 2 -, or a combination of two of these groups, where no two O atoms are bonded to one another, or a single bond and n and m each denote 0, 1 or 2, where n + m denotes 0, 1, 2 or 3. L 1 and L 2 both denote F, (a) a trans-1,4-cyclohexylene radical, in which, in addition, one or two non-adjacent CH 2 groups may be replaced by -O- and/or -S-, (b) (c) a 1,4-phenylene radical, in which, in addition, one or two non-adjacent CH groups may be replaced by N, or (d) a radical selected from the group 1,4-bicyclo[2.2.2]octylene, 1,3-bicyclo[1.1.1]pentylene, spiro[3.3]heptane-2,4-diyl, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl and 1,2,3,4-tetrahydronaphthalene-2,6-diyl, R 1 and R 2 each, independently of one another, denote H, halogen, -CN, -SCN, -SF 5, -CF 3, -CHF 2, -CH 2 F, -OCF 3, -OCHF 2, an alkyl group having 1 to 15 C atoms which is monosubstituted by CN or CF 3 or at least monosubstituted by halogen, where, in addition, one or more CH 2 groups may each, independently of one another, be replaced by -O-, -S-, -CH=CH-, -CF=CF-, -CF=CH-, -CH=CF-, -CO-, -CO-O-, -O-CO- or -O-CO-O- in such a way that neither O nor S atoms are linked directly to one another, or R 1 and R 2 each, independently of one another, denote H, halogen, -CN, -SCN, -SF 5, -CF 3, -CHF 2, -CH 2 F, -OCF 3, -OCHF 2, an alkyl group having 1 to 15 C atoms which is monosubstituted by CN or CF 3 or at least monosubstituted by halogen, where, in addition, one or more CH 2 groups may each, independently of one another, be replaced by -O-, -S-, -CH=CH-, -CF=CF-, -CF=CH-, -CH=CF-, -CO-, -CO-O-, -O-CO- or -O-CO-O- in such a way that neither O nor S atoms are linked directly to one another, or R 1 and R 2 denotes alkyl or alkoxy having 1 to 12 C atoms, alkoxyalkyl, alkenyl or alkenyloxy having 2 to 12 C atoms and the other, independently of the first, like-wise denotes alkyl or alkoxy having 1 to 12 C atoms, alkoxyalkyl, alkenyl or alkenyloxy having 2 to 12 C atoms or alternatively F, Cl, Br, -CN, -SCN, -SF 5, -CF 3, -CHF 2, -CH 2 F, -OCF 3 or -OCHF 2, Z 1 and Z 2 each, independently of one another, denote -CH2-CH2-, -CF 2 -CF 2 -, -CF2-CH2-, -CH 2 -CF 2 -, -CH=CH-, -CF=CF-, -CF=CH-, -CH=CF-, -C≡C-, -COO-, -OCO-, -OCH 2 -, -CH 2 O-, -CF 2 O-, -OCF 2 -, or a combination of two of these groups, where no two O atoms are bonded to one another, or a single bond and n and m each denote 0, 1 or 2, where n + m denotes 0, 1, 2 or 3.