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Synthesis, Structure, and Reactivity of Chiral Rhenium Cycloalkene Complexes of the Formula ; Facile Vinylic Deprotonation of a Coordinated Alkene
Author(s) -
Kowalczyk James J.,
Arif Atta M.,
Gladysz J. A.
Publication year - 1991
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19911240410
Subject(s) - chemistry , deprotonation , cyclopentadienyl complex , cycloalkene , ligand (biochemistry) , reactivity (psychology) , alkene , rhenium , crystal structure , stereochemistry , crystallography , double bond , medicinal chemistry , polymer chemistry , catalysis , organic chemistry , medicine , ion , biochemistry , receptor , alternative medicine , pathology
Reactions of [(η 5 ‐C 5 H 5 )Re(NO)(PPh 3 )(ClC 6 H 5 )] + BF − 4 and ( n = 5, a ; 6, b ; 7, c ; 8, d ) give cycloalkene complexes ( 6a – d , 94 to 79%). A crystal structure of the methylcyclopentadienyl analog of 6a shows the Re – plane and Re – PPh 3 bond to be coplanar, with the vinyl protons syn to the cyclopentadienyl ligand. Reaction of 6a and t BuO − K + leads to the vinyl complex ( 9a , 90%) instead of expected allyl complex ( 10a ) Analogous reactions of 6b – d give varying mixtures of 9b – d/10b – d . HBF 4 · OEt 2 and 9a react to form the cyclopentylidene complex ( 10 + BF − 4 , 96%), the stability of which precludes any intermediacy in the deprotonation of 6a . A crystal structure of 11 + PF − 6 shows the ReCC planes to be perpendicular to the Re – P bond. Spectroscopic features of compounds 6 are analyzed in detail, and NMR data show a high barrier to cyclopentylidene ligand rotation in 11 + BF − 4 (ΔG≢ (110°C) ≥ 19 kcal/mol).