Radical Reaction Mechanisms of and at Organic Germanium, Tin and Lead

Taraban, Marc B.; Волкова, О. С.; Kruppa, Alexander I.; Leshina, Tatyana V.

doi:10.1002/9780470682531.pat0261

Cited by 1 publication

(1 citation statement)

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“…Germanium-centered radicals are key intermediates in a broad range of chemical reactions. − The reactivity of the related tin- and silicon-based radicals has been well described, but the reactivity of the related Ge-centered radicals is much less explored. − …”

Section: Introductionmentioning

confidence: 99%

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

Neshchadin¹,

Rosspeintner

Grießer³

et al. 2013

J. Am. Chem. Soc.

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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 × 10(8) and 3.2 ± 0.2 × 10(8) 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.

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