1397198-00-3Relevant academic research and scientific papers
A cooperative role for the counteranion in the PCl5-initiated living, cationic chain growth polycondensation of the phosphoranimine Cl 3P=NSiMe3
Blackstone, Vivienne,Pfirrmann, Stefan,Helten, Holger,Staubitz, Anne,Presa Soto, Alejandro,Whittell, George R.,Manners, Ian
, p. 15293 - 15296 (2012)
The counteranion associated with the cationic initiator [Cl 3P=N=PCl3]+ ([4]+) generated during the PCl5-initiated living, cationic chain growth polycondensation of the N-silylphosphoranimine Cl3P=NSiMe3 (3) to give poly(dichlorophosphazene), [N=PCl2]n (2), has been found to have a dramatic effect on the polymerization. When the counteranion of [4]+ was changed from PCl6- or Cl- to the weakly coordinating anions [Bar*F4] - and [BArF4]- (Ar* F = 3,5-{CF3}2C6H3, ArF = C6F5) instead of the polymerization of 3 being complete in 4-6 h, no reaction was observed after 24 h. Remarkably, the polymerization of 3 may be initiated by Cl- anions even in the absence of an active cation such as [4]+. However, in the presence of [4]+, the reaction proceeded significantly faster and allowed for molecular weight control. These results reveal that the currently accepted mechanism for the PCl5-initiated living polymerization of 3 needs to be revised to reflect the key role of the counteranion present.
