The invention relates to a compound of formula (I), wherein: A represents a binding group comprising at least one nitrogen atom; Q1 and Q2 represent, independently of one another, a linkage group; x is an integer between 2 and 6; and Z represents the group of formula (I), wherein each R′ represents, independently, an alkyl group having between 1 and 4 carbon atoms. The invention also relates to a rubber composition comprising said compound.