A compound represented by the formula: wherein R is selected from the group consisting of (i) substituted or unsubstituted alkyl with C=0 to 12 inclusive; (ii) substituted or unsubstituted aryl; and (iii) substituted and unsubstituted alkylaryl; wherein X1, X2, X3 and X4 are each selected from the group consisting of alkyl, aryl, alkylaryl groups and hydrogen; wherein R1, R2, R3, and R4 are each selected from the group consisting of alkyl, aryl, alkylaryl groups and hydrogen and R2 and R3 may optionally be bridged by a polymethylene group; wherein when C=0 in R, the combined group R1 R2 is the same as the combined group R3 R4; and wherein when C=1 in R, each of R1, R2, R3, and R4 are hydrogen.