. "R1 and R2 are each, independently, alkyl or aryl groups having at least 3 carbon atoms, R3 and R4 are each, independently, a hydrogen atom, a halogen atom, or a hydrocarbyl group, R3??? and R4??? are as defined for R3 and R4, and R5 is a bridging group that links the two imidazoline rings. 6." . . . .