Premium
The Role of Ate Complexes in Halogen(Metalloid)–Metal Exchange Reactions: A Theoretical Study
Author(s) -
Boche Gernot,
Schimeczek Michael,
Cioslowski Jerzy,
Piskorz Pawel
Publication year - 1998
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(199809)1998:9<1851::aid-ejoc1851>3.0.co;2-n
Subject(s) - chemistry , electronegativity , halogen , halide , steric effects , trihalide , lithium (medication) , inorganic chemistry , bromide , transition metal , iodine , magnesium , metalloid , metal , computational chemistry , organic chemistry , catalysis , alkyl , medicine , endocrinology
Correlated electronic structure calculations predict that [(CH 3 ) n +1 X] − methyl ate anions, where X is an element of the main groups 14, 15, 16, or 17 up to Bi, possess widely varying stabilities that are governed by the electronegativities of their central atoms X. These stabilities correlate well with the propensities of the elements in question to undergo exchange with lithium and magnesium halide, except in the cases where steric hindrance in the transition states of the exchange reactions is important. These findings are nicely confirmed by calculations of the transition states [(CH 3 ) 2 XLi] # (X = Cl, Br, I) and [(CH 3 ) 3 SeLi] # of the corresponding degenerate exchange reactions CH 3 X (X = Cl, Br, I) + CH 3 Li and (CH 3 ) 2 Se + CH 3 Li, respectively. The computed relative stabilities of the mixed [R–I–CH 3 ] − ate anions of iodine (where R = phenyl, ethynyl, vinyl, ethyl, or cyclopropyl) are in excellent agreement with the experimentally observed equilibria of the corresponding lithium–iodine exchange reactions. The recent experimental observation of a highly stable α‐iodine‐substituted iodine ate complex as an intermediate in an iodine–magnesium bromide exchange reaction is also corroborated by our studies. Thus, the present calculations provide strong evidence for ate complexes being key intermediates in halogen(metalloid)–lithium(magnesium halide) exchange reactions.