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An Insight into the Reversible Dissociation and Chemical Reactivity of a Sterically Encumbered Diphosphane (Eur. J. Inorg. Chem. 25/2012)
Author(s) -
Förster Daniela,
Dilger Herbert,
Ehret Fabian,
Nieger Martin,
Gudat Dietrich
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201290077
Subject(s) - chemistry , steric effects , radical , homolysis , dissociation (chemistry) , photochemistry , bond dissociation energy , bond cleavage , reactivity (psychology) , medicinal chemistry , alkyne , stereochemistry , organic chemistry , catalysis , medicine , alternative medicine , pathology
The cover picture shows the amazingly diverse reactivity of a sterically encumbered diphosphane towards alkynes. The steric hindrance facilitates homolytic cleavage of the P–P bond: the experimentally determined dissociation energy of 79 kJ mol –1 is substantially lower than the gas‐phase dissociation energies of small diphosphanes, and a substantial amount of the diphosphane dissociates even at ambient temperature into phosphanyl radicals (the double horse, which is reminiscent of the arms of the city of Stuttgart, is meant as an allegory for this process). Chemical reactions of this equilibrium mixture may either follow a radical mechanism as in the trans addition of two radicals to the triple bond of an unactivated alkyne. Alternatively, a substrate can bypass the radicals to react with the intact diphosphane, as in the unexpected ring metathesis reaction with an electron‐poor alkyne. Details are discussed in the article by D. Gudat et al. on p. 3989 ff.