Reduction of Bromo- and Iodo-2,6-bis(diphenylphosphanylmethyl)benzene with Magnesium and Calcium
Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University of Jena, 07745 Jena, Germany
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Academic Editor: Lee J. Higham
Inorganics 2016, 4(4), 39; https://doi.org/10.3390/inorganics4040039
Received: 1 November 2016
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Revised: 21 November 2016
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Accepted: 25 November 2016
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Published: 1 December 2016
(This article belongs to the Special Issue Organophosphorus Chemistry 2016)
Arylmagnesium and -calcium reagents are easily accessible; however, ether degradation processes limit storability, especially of the calcium-based heavy Grignard reagents. Ortho-bound substituents with phosphanyl donor sites usually block available coordination sites and stabilize such complexes. The reaction of bromo-2,6-bis(diphenylphosphanylmethyl)benzene (1a) with magnesium in tetrahydrofuran yields [Mg{C6H3-2,6-(CH2PPh2)2}2] (2) after recrystallization from 1,2-dimethoxyethane. However, the similarly performed reduction of bromo- (1a) and iodo-2,6-bis(diphenylphosphanylmethyl)benzene (1b) with calcium leads to ether cleavage and subsequent degradation products. α-Deprotonation of tetrahydrofuran (THF) yields 1,3-bis(diphenylphosphanylmethyl)benzene. Furthermore, the insoluble THF adducts of dimeric calcium diphenylphosphinate halides, [(thf)3Ca(X)(µ-O2PPh2)]2 [X = Br (3a), I (3b)], precipitate verifying ether decomposition and cleavage of P–C bonds. Ether adducts of calcium halides (such as [(dme)2(thf)CaBr2] (4)) form, supporting the initial Grignard reaction and a subsequent Schlenk-type dismutation reaction.
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Keywords:
Grignard reagent; arylmagnesium halide; phosphinates; calcium phosphinates; direct synthesis; ether degradation; calcium bromide
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MDPI and ACS Style
Koch, A.; Krieck, S.; Görls, H.; Westerhausen, M. Reduction of Bromo- and Iodo-2,6-bis(diphenylphosphanylmethyl)benzene with Magnesium and Calcium. Inorganics 2016, 4, 39. https://doi.org/10.3390/inorganics4040039
AMA Style
Koch A, Krieck S, Görls H, Westerhausen M. Reduction of Bromo- and Iodo-2,6-bis(diphenylphosphanylmethyl)benzene with Magnesium and Calcium. Inorganics. 2016; 4(4):39. https://doi.org/10.3390/inorganics4040039
Chicago/Turabian StyleKoch, Alexander, Sven Krieck, Helmar Görls, and Matthias Westerhausen. 2016. "Reduction of Bromo- and Iodo-2,6-bis(diphenylphosphanylmethyl)benzene with Magnesium and Calcium" Inorganics 4, no. 4: 39. https://doi.org/10.3390/inorganics4040039
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