ChemInform Abstract: THE REACTIONS OF ETHOXY RADICALS WITH OPTICALLY ACTIVE TERTIARY PHOSPHINES. STEREOCHEMISTRY OF THE SUBSTITUTION PROCESS AND THE QUESTION OF PERMUTATION MODES FOR THE POSSIBLE PHOSPHORANYL RADICAL INTERMEDIATES

1983 ◽  
Vol 14 (52) ◽  
Author(s):  
W. G. BENTRUDE ◽  
M. MORIYAMA ◽  
H.-D. MUELLER ◽  
A. E. SOPCHIK
Keyword(s):  
Optically Active ◽  
Radical Intermediates ◽  
Substitution Process ◽  
Tertiary Phosphines ◽  
Phosphoranyl Radical

Homolytic Substitution at Phosphorus: An Ab initio Study of the Reaction of Hydrogen Atom and Methyl Radical With Phosphine and Methylphosphine

1995 ◽  
Vol 48 (2) ◽  
pp. 175 ◽  
Author(s):  
CH Schiesser ◽  
LM Wild
Keyword(s):  
Hydrogen Atom ◽  
Ab Initio ◽  
Phosphorus Atom ◽  
Methyl Radical ◽  
Orbital Theory ◽  
Energy Barriers ◽  
Radical Intermediates ◽  
Phosphoranyl Radical ◽  
High Level ◽  
Homolytic Substitution

Homolytic substitution reactions of hydrogen atom and methyl radical at the phosphorus atom in phosphine and methylphosphine have been examined by high-level ab initio molecular orbital theory. MP4SDTQ/6-31G**//MP2(FC)/6-31G** calculations predict that free-radical attack at the phosphorus atom in phosphines is facile, with energy barriers of 14-33 kJ mol-1 and likely to involve hypervalent phosphoranyl radical intermediates. These intermediates, in turn, are found to have dissociative energy barriers of 10-31 kJ mol-1, depending on leaving group, and are unlikely to undergo pseudorotation prior to dissociation. MP5/6-31G**//MP2/6-31G** calculations indicate that permutational isomerism of phosphoranyl radical is likely to involve barriers of 145 and 127 kJ mol-1 for mechanisms involving transition states of D4h and C4v symmetry respectively.

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