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- Title
An Insight into the Reversible Dissociation and Chemical Reactivity of a Sterically Encumbered Diphosphane.
- Authors
Förster, Daniela; Dilger, Herbert; Ehret, Fabian; Nieger, Martin; Gudat, Dietrich
- Abstract
The known 1,1′,3,3′-tetrahydro-2,2′-bi-1,3,2-diazaphosphole 4a was for the first time synthesized on a preparative scale and characterized by spectroscopy. Equilibrium constants for the dissociation 4a [rlarr2] 2 5a were determined from quantitative variable-temperature electron paramagnetic resonance(VT-EPR) studies and were used to obtain thermochemical data for the P-P bond homolysis. The calculated bond dissociation energy of 79(1) kJ mol-1 is substantially lower than the gas-phase dissociation energies of small diphosphanes. Modeling of the molecular structure of 4a by DFT calculations was feasible if dispersion effects were included, but the calculations still failed to give a reasonable account of the energetics of the dissociation process. Chemical reactions of 4a with alkynes proceeded, depending on substrate structure, either as a radical-induced diphosphanation of the triple bond or by a nonradical reaction to give an unprecedented ring metathesis.
- Subjects
DIPHOSPHINE; PHOSPHINE synthesis; EQUILIBRIUM constant (Chemistry); ELECTRON paramagnetic resonance; DOUBLE bonds; HOMOLYSIS; MOLECULAR structure; DENSITY functional theory
- Publication
European Journal of Inorganic Chemistry, 2012, Vol 2012, Issue 25, p3989
- ISSN
1434-1948
- Publication type
Article
- DOI
10.1002/ejic.201200633