Lubricant additive compositions containing thiophosphates and thiophosphate derivatives

A compound of formula (I)

• or a tribologically acceptable salt thereof,
• wherein A is:
• each R1 is the same or different and is independently selected from alkyl;
• each R2 and R3 are independently selected from H and alkyl;
• Y is —R4—R5—R6;
• R4 is alkylene;
• R5 is —C(O)—;
• R6 is selected from the group consisting of alkyl and hydroxy;
• m is an integer from 2 to 8;
• X1 is R8 or Z;
• X2 is selected from the group consisting of R8,
• R8 is alkyl;
• and
• Z is
• wherein when X2 is R8, X1 is Z.