Thiophosphates and thiophosphate derivatives as lubricant additives

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, alkenyl, cycloalkyl, cycloalkylalkyl, aryl, and aralkyl, wherein said aryl and aralkyl are optionally substituted with one to three substituents each independently selected from alkyl and alkenyl;
• each R2 and R3 are independently selected from H, alkyl, alkenyl, cycloalkyl and cycloalkylalkyl;
• Y is selected from the group consisting of alkyl, alkoxyalkyl, benzyl, and —R4-R5-R6;
• R4 is alkylene;
• R5 is selected from the group consisting of a bond, alkylene;
• —C(O)— and —C(R7)—;
• R6 is selected from the group consisting of alkyl, hydroxyalkyl, hydroxyalkyleneoxy, hydroxy and alkoxy,
• R7 is 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, alkenyl, cycloalkyl, cycloalkylalkyl, aryl, and aralkyl, wherein said aryl and aralkyl are optionally substituted with one to three substituents each independently selected from alkyl and alkenyl;
• and
• Z is
• wherein when X2 is R8, X1 is Z.