Alkynyl-tolanes, liquid-crystal mixtures containing them and components for high-frequency technology

A compound of formula I

• in which
• where in the 1,4-phenylene groups, one C—H group or two C—H groups are replaced by N, which one C—H group or two C—H groups are present as a result of L0 being H on the carbon atom of said one C—H group or two C—H groups,
• where in the 1,4-phenylene groups, one C—H group or two C—H groups are optionally replaced by N,
• L0 on each occurrence, independently of one another, denotes H, Br, Cl, F, —CN, —NCS, —SCN, SF5, C1-C10 alkyl, C1-C10 alkoxy, C3-C6 cycloalkyl or a mono- or polyfluorinated C1-C10 alkyl or alkoxy group,
• R01 and R02 each, independently of one another, denote a halogenated or unsubstituted alkyl radical having 1 to 15 C atoms, in which one or more CH2 groups are optionally replaced, independently of one another, by —C≡C—, —CH═CH—, —CF═CF—, —CF═CH—, —CH═CF—, —(CO)O—, —O(CO)—, —(CO)—, —O— or —S— in such a way that O or S atoms are not linked directly to one another, and R01 also denotes ethynyl, and
• R03 and R04 each, independently of one another, denote a halogenated or unsubstituted alkyl radical having 1 to 6 C atoms, in which one or more CH2 groups are optionally replaced, independently of one another, by —C≡C—, —CH═CH—, —CF═CF—, —CF═CH—, —CH═CF—, —(CO)O—, —O(CO)—, —(CO)—, —O— or —S— in such a way that O or S atoms are not linked directly to one another.