A compound of the formula: wherein A is oxygen (-O-) or a polyorganosiloxanyl residue comprising at least one siloxy unit selected from the group consisting of R 1 3 SiO 1/2, R 1 2 SiO 2/2, R 1 SiO 3/2 and SiO 4/2, wherein R 1 is an organic group and the polyorganosiloxanyl residue is bonded to Si via an oxygen atom, with the provisos that (i) if A is oxygen (-O-), then z is 2, and (ii) if A is a polyorganosiloxanyl residue, then the polyorganosiloxanyl residue contains at least two siloxy groups which can bond to the silicon atom; each R 2 is independently selected from the group consisting of a straight chain alkylene group having from 1 to 10 carbon atoms, branched chain alkylene group having from 3 to 10 carbon atoms, a cycloalkylene group having from 3 to 10 carbon atom, an arylene group having from 6 to 12 carbon atoms, an aralkylene group having from 7 to 10 carbon atoms and an arenylene group having from 7 to 10 carbon atom, preferably methylene, propylene, 2-methylbutylene and 2,2-dimethylbutylene and more preferable a branched chain alkylene group having from 3 to 10 carbon atoms, such as 2,2-dimethylbutylene bound in particular to the Si and N atoms as shown schematically below: each R 3 and R 4 is independently selected from the group consisting of a straight chain alkyl group of from 1 to 10 carbon atoms, a branched chain alkyl group having from 3 to 10 carbon atoms and a cycloalkyl group having from 3 to 10 carbon atoms; each R 5 and R 6 is independently selected from the group consisting of a straight chain alkyl group of from 1 to 10 carbon atoms, a branched chain alkyl group having from 3 to 10 carbon atoms and a cycloalkyl group having from 3 to 10 carbon atoms; x is an integer independently 0 or 1, preferably x is 0; and z is an integer independently from 2 to 8, preferably 2, 3 or 4, and more preferably 2. A is oxygen (-O-) or a polyorganosiloxanyl residue comprising at least one siloxy unit selected from the group consisting of R 1 3 SiO 1/2, R 1 2 SiO 2/2, R 1 SiO 3/2 and SiO 4/2, wherein R 1 is an organic group and the polyorganosiloxanyl residue is bonded to Si via an oxygen atom, with the provisos that (i) if A is oxygen (-O-), then z is 2, and (ii) if A is a polyorganosiloxanyl residue, then the polyorganosiloxanyl residue contains at least two siloxy groups which can bond to the silicon atom; each R 2 is independently selected from the group consisting of a straight chain alkylene group having from 1 to 10 carbon atoms, branched chain alkylene group having from 3 to 10 carbon atoms, a cycloalkylene group having from 3 to 10 carbon atom, an arylene group having from 6 to 12 carbon atoms, an aralkylene group having from 7 to 10 carbon atoms and an arenylene group having from 7 to 10 carbon atom, preferably methylene, propylene, 2-methylbutylene and 2,2-dimethylbutylene and more preferable a branched chain alkylene group having from 3 to 10 carbon atoms, such as 2,2-dimethylbutylene bound in particular to the Si and N atoms as shown schematically below: each R 3 and R 4 is independently selected from the group consisting of a straight chain alkyl group of from 1 to 10 carbon atoms, a branched chain alkyl group having from 3 to 10 carbon atoms and a cycloalkyl group having from 3 to 10 carbon atoms; each R 5 and R 6 is independently selected from the group consisting of a straight chain alkyl group of from 1 to 10 carbon atoms, a branched chain alkyl group having from 3 to 10 carbon atoms and a cycloalkyl group having from 3 to 10 carbon atoms; x is an integer independently 0 or 1, preferably x is 0; and z is an integer independently from 2 to 8, preferably 2, 3 or 4, and more preferably 2.