1416042-57-3Relevant academic research and scientific papers
An insight into the reversible dissociation and chemical reactivity of a sterically encumbered diphosphane
Foerster, Daniela,Dilger, Herbert,Ehret, Fabian,Nieger, Martin,Gudat, Dietrich
, p. 3989 - 3994 (2012/11/13)
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. The tendency of sterically encumbered diphosphanes to dissociate at room temperature into phosphanyl radicals is explained by a low P-P bond enthalpy of 79 kJ mol -1. Still, reactions with alkynes do not necessarily proceed as radical additions to the triple bond but may proceed by direct attack of the diphosphane at the alkyne, yielding unexpected ring metathesis products with intact P-P bonds. Copyright
Formation of a new class of 7π radicals via sterically induced P-P bond cleavage of the dimers [(CH)2(NR)2P]2
Edge, Ruth,Less, Robert J.,McInnes, Eric J. L.,Müther, Kristine,Naseri, Vesal,Rawson, Jeremy M.,Wright, Dominic S.
supporting information; experimental part, p. 1691 - 1693 (2009/08/08)
The 2c-2e- P-P bonded dimers [(CH)2(NR) 2P]2 dissociate in solution to give the persistent new 7π radicals [(CH)2(NR)2P]?, which are isoelectronic with the well known S/N thiazol
