A compound of formula I wherein (Het)Ar is linked via a carbon atom and is selected from the group consisting of phenyl, naphthyl and a mono- or bicyclic heteroaromatic group having 5 to 10 ring member atoms of which 2 to 9 ring members are carbon atoms and either one ring member is an unsubstituted or substituted heteroatom selected from N, NH, NR N, O, S, S(=O) and S(=O) 2, or one ring member is N and a second ring member is selected from N, NH, NR N, O, S, S(=O) and S(=O) 2, or two ring members are N and a third ring member is selected from N, NH, NR N, O, S, S(=O) and S(=O) 2, wherein in naphthyl, the ring not attached to the indanyl-O atom of formula I may be partially saturated, wherein in bicyclic heteroaromatic groups the ring not attached to the indanyl-O atom of formula I may be partially saturated, while at least one aromatic ring includes a heteroatom, and optionally one ring member in the partially or fully saturated bridge is replaced by N, NH, NR N, O, S, S(=O) or S(=O) 2, or one ring member in the partially or fully saturated bridge is replaced by N, NH or NR N and a second ring member is replaced by NH, NR N, O, S, C(=O), S(=O) or S(=O) 2, or two not vicinal ring members in a fully saturated bridge are replaced by O atoms, wherein any of these groups is optionally and independently substituted with 1 to 5 R 1 groups; R 1 is selected from the group consisting of F, Cl, Br, I, CN, NO 2, NH 2, C 1-4 -alkyl-NH-, (C 1-4 -alkyl) 2 N-, C 1-4 -alkyl-, C 2-4 -alkenyl-, C 2-4 -alkynyl-, OH, HO-C 1-4 -alkyl, C 1-4 -alkyl-O-, C 1-4 -alkyl-O-C 1-4 -alkyl, C 1-4 -alkyl-S-, C 1-4 -alkyl-S(=O)-, C 1-4 -alkyl-S(=O) 2 -, C 3-6 -cycloalkyl-, and C 3-6 -cycloalkyl-O-, wherein any alkyl and cycloalkyl group or submoiety is optionally substituted with 1 to 5 F atoms; and R N is selected from the group consisting of C 1-4 -alkyl, C 3-4 -alkenyl, HO-C 1-4 -alkyl, C 1-4 -alkyl-O-C 1-4 -alkyl, C 1-4 -alkyl-C(=O)-, C 1-4 -alkyl-S(=O) 2 -, and C 3-6 -cycloalkyl-, wherein any alkyl and cycloalkyl group or submoiety is optionally substituted with 1 to 5 F atoms; wherein in any definition mentioned hereinbefore and if not specified otherwise, any alkyl group or sub-group may be straight-chained or branched, or a salt thereof. (Het)Ar is linked via a carbon atom and is selected from the group consisting of phenyl, naphthyl and a mono- or bicyclic heteroaromatic group having 5 to 10 ring member atoms of which 2 to 9 ring members are carbon atoms and either one ring member is an unsubstituted or substituted heteroatom selected from N, NH, NR N, O, S, S(=O) and S(=O) 2, or one ring member is N and a second ring member is selected from N, NH, NR N, O, S, S(=O) and S(=O) 2, or two ring members are N and a third ring member is selected from N, NH, NR N, O, S, S(=O) and S(=O) 2, wherein in naphthyl, the ring not attached to the indanyl-O atom of formula I may be partially saturated, wherein in bicyclic heteroaromatic groups the ring not attached to the indanyl-O atom of formula I may be partially saturated, while at least one aromatic ring includes a heteroatom, and optionally one ring member in the partially or fully saturated bridge is replaced by N, NH, NR N, O, S, S(=O) or S(=O) 2, or one ring member in the partially or fully saturated bridge is replaced by N, NH or NR N and a second ring member is replaced by NH, NR N, O, S, C(=O), S(=O) or S(=O) 2, or two not vicinal ring members in a fully saturated bridge are replaced by O atoms, wherein in naphthyl, the ring not attached to the indanyl-O atom of formula I may be partially saturated, wherein in bicyclic heteroaromatic groups the ring not attached to the indanyl-O atom of formula I may be partially saturated, while at least one aromatic ring includes a heteroatom, and optionally one ring member in the partially or fully saturated bridge is replaced by N, NH, NR N, O, S, S(=O) or S(=O) 2, or one ring member in the partially or fully saturated bridge is replaced by N, NH or NR N and a second ring member is replaced by NH, NR N, O, S, C(=O), S(=O) or S(=O) 2, or two not vicinal ring members in a fully saturated bridge are replaced by O atoms, one ring member in the partially or fully saturated bridge is replaced by N, NH, NR N, O, S, S(=O) or S(=O) 2, or one ring member in the partially or fully saturated bridge is replaced by N, NH or NR N and a second ring member is replaced by NH, NR N, O, S, C(=O), S(=O) or S(=O) 2, or two not vicinal ring members in a fully saturated bridge are replaced by O atoms, R 1 is selected from the group consisting of F, Cl, Br, I, CN, NO 2, NH 2, C 1-4 -alkyl-NH-, (C 1-4 -alkyl) 2 N-, C 1-4 -alkyl-, C 2-4 -alkenyl-, C 2-4 -alkynyl-, OH, HO-C 1-4 -alkyl, C 1-4 -alkyl-O-, C 1-4 -alkyl-O-C 1-4 -alkyl, C 1-4 -alkyl-S-, C 1-4 -alkyl-S(=O)-, C 1-4 -alkyl-S(=O) 2 -, C 3-6 -cycloalkyl-, and C 3-6 -cycloalkyl-O-, wherein any alkyl and cycloalkyl group or submoiety is optionally substituted with 1 to 5 F atoms; and R N is selected from the group consisting of C 1-4 -alkyl, C 3-4 -alkenyl, HO-C 1-4 -alkyl, C 1-4 -alkyl-O-C 1-4 -alkyl, C 1-4 -alkyl-C(=O)-, C 1-4 -alkyl-S(=O) 2 -, and C 3-6 -cycloalkyl-, wherein any alkyl and cycloalkyl group or submoiety is optionally substituted with 1 to 5 F atoms;