Acylgermanes: Photoinitiators and Sources for Ge-Centered Radicals. Insights into their Reactivity

Neshchadin, Dmytro; Rosspeintner, Arnulf; Griesser, Markus; Lang, Bernhard Felix; Mosquera Vazquez, Sandra; Vauthey, Eric; Gorelik, Vitaly; Liska, Robert; Hametner, Christian; Ganster, Beate; Saf, Robert; Moszner, Norbert; Gescheidt, Georg

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Title		Acylgermanes: Photoinitiators and Sources for Ge-Centered Radicals. Insights into their Reactivity
Authors		Neshchadin, Dmytro Rosspeintner, Arnulf Griesser, Markus Lang, Bernhard Felix Mosquera Vazquez, Sandra Vauthey, Eric Gorelik, Vitaly Liska, Robert Hametner, Christian Ganster, Beate Saf, Robert Moszner, Norbert Gescheidt, Georg show all authors [1 - 13]
Published in		Journal of the American Chemical Society. 2013, vol. 135, no. 46, p. 17314-17321
Abstract		Acylgermanes have been shown to act as efficient photoinitiators. In this investigation we show how dibenzoyldiethylgermane 1 reacts upon photoexcitation. Our real-time investigation utilizes femto- and nanosecond transient absorption, time-resolved EPR (50 ns), photo-chemically induced dynamic nuclear polarization, DFT calculations, and GC-MS analysis. The benzoyldiethylgermyl radical G• is formed via the triplet state of parent 1. On the nanosecond time scale this radical can recombine or undergo hydrogen-transfer reactions. Radical G• reacts with butyl acrylate at a rate of 1.2 ± 0.1 × 108 and 3.2 ± 0.2 × 108 M–1 s–1, in toluene and acetonitrile, respectively. This is ˜1 order of magnitude faster than related phosphorus-based radicals. The initial germyl and benzoyl radicals undergo follow-up reactions leading to oligomers comprising Ge–O bonds. LC-NMR analysis of photocured mixtures containing 1 and the sterically hindered acrylate 3,3-dimethyl-2-methylenebutanoate reveals that the products formed in the course of a polymerization are consistent with the intermediates established at short time scales.
Identifiers		DOI: 10.1021/ja404433u
Full text		Article (Published version) (398 Kb) - Limited access to UNIGE Other version: http://pubs.acs.org/doi/abs/10.1021/ja404433u
Structures		Faculté des sciences / Section de chimie et biochimie / Département de chimie physique
Research group		Groupe Vauthey
Citation (ISO format)		NESHCHADIN, Dmytro et al. Acylgermanes: Photoinitiators and Sources for Ge-Centered Radicals. Insights into their Reactivity. In: Journal of the American Chemical Society, 2013, vol. 135, n° 46, p. 17314-17321. https://archive-ouverte.unige.ch/unige:31278