S-indacene and indeno[5,6-d][1,3]dioxol-derivatives and use thereof as components of liquid-crystal mixtures

1,2,3,6,7,8-Hexahydro-s-indacene and 6,7-dihydro-5H-indeno-[5,6-d]-1,3-dioxole derivatives of the general formula I

• in which
• R1 denotes H, halogen, a linear or branched alkyl radical having 1 to 15 C atoms which is unsubstituted, monosubstituted by CN or CF3 or at least monosubstituted by halogen and in which one or more CH2 groups may each, independently of one another, be replaced by —O—, —S—, —CO—, —(CO)O—, —CH═CH—, —CH═CF—, —CF═CF— or —C≡C— in such a way that heteroatoms are not linked directly to one another and asymmetrical groups may be present in both orientations,
• A1 in each case, independently of one another, identically or differently, denotes
• a) trans-1,4-cyclohexylene, in which, in addition, one or more non-adjacent CH2 groups may be replaced by —S—, tetrahydropyran-2,5-diyl or 1,3-dioxane-2,5-diyl,
• b) 1,4-phenylene, in which one or two CH groups may be replaced by N and in which one or more H atoms may be replaced by halogen,
• c) a radical from the group 1,4-bicyclo[2.2.2]octylene, spiro[3.3]heptane-2,6-diyl, cyclobutane-1,3-diyl, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl and 1,2,3,4-tetrahydronaphthalene-2,6-diyl, in which, in addition, CH may be replaced by N and in which, in addition, one or more H atoms may be replaced by halogen, or
• d) 1,4-cyclohexenylene,
• X denotes —CH2—, —CF2— or —O—,
• Y denotes F, Cl, CF3, CN, NCS, SCN, SF5 or 2- to 6-C perfluoroalkyl,
• in each case, independently of one another, in the case of asymmetrical bridging units Z1 in either of the two orientations, denotes a single bond, —CH2O—, —(CO)O—, —CF2O—, —CF═CF—, —CH2CH2CF2O—, —CF2CF2—, —CH2CF2—, —CH2CH2—, —CH═CH—, —CH═CF— or —C≡C—, and
• n denotes 0, 1, 2 or 3.