A compound of the formula: ##STR35## wherein R1 is C1 C6 lower alkyl, C1 C6 alkylthio, C6 C10 aryl, C7 C16 arylalkyl, C6 C10 arylthio, {HEAD ~ C7 C16 arylalkylthio}, cyano, C1 C6 perfluorinated lower alkyl, or ##STR36## wherein R is a chain of 1 5 carbon atoms; and R2, R3, and {TAIL ~ R4} are each independently: 
A compound of the formula : # # STR35 # # wherein R1 is C1 C6 lower alkyl , C1 C6 alkylthio , C6 C10 aryl , C7 C16 arylalkyl , C6 C10 arylthio , { HEAD ~ C7 C16 arylalkylthio } , cyano , C1 C6 perfluorinated lower alkyl , or # # STR36 # # wherein R is a chain of 1 5 carbon atoms ; and R2 , R3 , and { TAIL ~ R4 } are each independently :
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH