ISSN:
0044-2313
Keywords:
Diphosphane(4)
;
Diborane(6)
;
Borane-tetrahydrofuran
;
Diphosphane-borane
;
Diphosphane-1,2-bis(borane)
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
Contributions to the Chemistry of Phosphorus. 239. On the Reaction of Diphosphane(4) with Diborane(6) and with THF-Borane: Formation of Diphosphane-borane, P2H4 · BH3, and Diphosphane-1,2-bis(borane), BH3 · P2H4 · BH3Diphosphane(4) always reacts with diborane(6) in the temperature range of -118 to -78°C, to furnish a mixture of diphosphane-borane, P2H4 · BH3 (1), and diphosphane-1,2-bis(borane), BH3 · P2H4 · BH3 (2), in addition to small amounts of triphosphane-1,3-bis(borane), BH3 · P3H5 · BH3, and phosphane-borane, BH3 · PH3, irrespective of the molar ratios of the reactants employed. The formation of the 1 : 1 adduct P2H4 · B2H6 reported in the literature [4] could not be confirmed. The structures of compounds 1 and 2 were investigated by nuclear magnetic resonance spectroscopy which revealed the complete, homolytic cleavage of diborane(6). As a result of the bonding of one BH3 group to diphosphane(4), the Lewis basicity of the other PH2 group is markedly reduced. Similar mixtures of products are obtained when the borane adduct THF · BH3 is employed in an analogous reaction. In the case of a 1 : 1 molar ratio of P2H4 : THF · BH3 at -78°C, the reaction furnishes compound 1 exclusively. This product can be isolated in the pure state and is found to be appreciably more stable than diphosphane(4).
Notes:
Diphosphan(4) reagiert mit Diboran(6) im Temperaturbereich von -118 bis -78°C bei unterschiedlichen Reaktandenverhältnissen stets zu einem Gemisch aus Diphosphan-boran, P2H4 · BH3 (1), und Diphosphan-1,2-bis(boran), BH3 · P2H4 · BH3 (2), mit etwas Triphosphan-1,3-bis(boran), BH3 · P3H5 · BH3, und Phosphan-boran, BH3 · PH3. Die Bildung des in der Literatur beschriebenen 1 : 1-Adduktes P2H4 · B2H6 [4] konnte nicht bestätigt werden. Nach kernresonanzspektroskopischen Strukturuntersuchungen der Verbindungen 1 und 2 findet eine vollständige homolytische Spaltung von Diboran(6) statt. Durch die Bindung einer BH3-Gruppe an Diphosphan(4) wird die Lewis-Basizität der anderen PH2-Gruppe deutlich herabgesetzt. Mit dem Boran-Addukt THF · BH3 entstehen ähnliche Produktgemische. Bei Reaktion im Molverhältnis P2H4 : THF · BH3 = 1 : 1 (-78°C) wird ausschließlich Verbindung 1 gebildet, die rein isolierbar und merklich beständiger als Diphosphan(4) ist.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/zaac.19966221206
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