{HEAD ~ Rb} is, independently at each occurrence, C1 6 alkyl, {TAIL ~ ORa}, Cl, F, Br, NRaRa1, CRa, CORa, CNRaRa1, S2NRaRa1, NRaS2Ra3, SpRa3, or CF3 
{ HEAD ~ Rb } is , independently at each occurrence , C1 6 alkyl , { TAIL ~ ORa } , Cl , F , Br , NRaRa1 , CRa , CORa , CNRaRa1 , S2NRaRa1 , NRaS2Ra3 , SpRa3 , or CF3
HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH