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Trapping of photogenerated group IV radicals by TEMPO: Potential new organometallic initiators for “living” free radical polymerization
Author(s) -
Skene W. G.,
Connolly Terrence J.,
Scaiano J. C.
Publication year - 2000
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/(sici)1097-4601(2000)32:4<238::aid-kin6>3.0.co;2-a
Subject(s) - chemistry , radical , flash photolysis , reaction rate constant , photochemistry , hydrogen atom abstraction , polymerization , radical polymerization , stoichiometry , polymer chemistry , kinetics , polymer , organic chemistry , physics , quantum mechanics
A series of trialkyl and triaryl organometallic radicals from group IV generated by hydrogen abstraction by tert ‐butoxyl radical from the parent hydrides have been examined using laser flash photolysis. The rate constants for the trapping of the metal‐centered radicals by the persistent radical TEMPO were measured and were found to be large and similar to those of the carbon‐centered radical systems, yet below the diffusion controlled limit. The metal‐centered radicals were found to be efficiently trapped by TEMPO and would appear to be candidates suitable for “living” free radical polymerization similar to carbon analogue stoichiometric initiators. The radical trapping rate constants for the trialkyl series (M = Si, Ge, Sn) were found to be 8.9 × 10 8 M −1 s −1 (M = Si), 7.2 × 10 8 M −1 s −1 (M = Ge), and 6.2 × 10 8 M −1 s −1 (M = Sn), respectively. The triaryl (Ph 3 M•) series gave slightly slower rates of 1.6 × 10 8 M −1 s −1 (M = Si), 3.4 × 10 8 M −1 s −1 (M = Ge), and 1.9 × 10 7 M −1 s −1 (M = Sn), respectively. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 238–244, 2000