REACTIONS OF BENZYLRHENIUM COMPLEXES (ETA-5-C5H5)RE(NO)(L)(CH2AR) WITH PH3C+PF6- - ANALYSIS OF THE RE-C-ALPHA ROTAMERS INVOLVED IN ALPHA-HYDRIDE ABSTRACTION Academic Article uri icon

abstract

  • Sequential reaction of [(5-C5H5)Re(NO)(PMe3)(CO) +BF4- (4) with CH3ONa, C6H5MgBr, and then BH3THF gives (5-C5H5)Re(NO)(PMe3)(CH 2C6H5) (7, 15%). Reaction of [5-C5H5)Re(NO)(PPh3)(= CH2)]+PF6- with o-CH3C6H4MgBr and mesitylmagnesium bromide gives (5-C5H5)Re(NO)(PPh3)(LH 2-(2-C6H4CH3)) (8,52%) and (5-C5H5)Re(NO)(PPh3)(CH 2(2,4,6-C6H2(CH3)3)) (9, 78%), respectively. Reactions of Ph3C+PF6- with 7, 8, and 9 are examined and compared to that of Ph3C+PF6- with (5-C5H5)Re-(NO)(PPh3)(CH 2C6H5) (1). With 1, the pro-R H is abstracted to give sc-[(5-C5H5)Re(NO)(PPh3)(= CHC6H5)]+PF6- (2k). In contrast, 9 undergoes exclusively pro-S H abstraction to give ac-[(5-C5H5)-Re(NO)(PPh 3)(=CH(2,4,6-C6H2(CH3) 3))]+PF6- (12t). With 8, both the pro-R and pro-S H are abstracted to give approximately equal amounts of sc- and ac-[(5-C5H5)Re(NO)(PPh 3)(=CH(2-C6H4CH3))] +PF6- (11k and 11t). With 7, the pro-S H is abstracted to give aC-[(5-C5H5)Re(NO)(PMe 3)(=CHC6H5)]+PF6- (13t). These data are discussed within the context of the Curtin-Hammett principle. Photolysis of 12t and 13t at -78C gives ca. 50:50 mixtures of t/k (ac/sc) Re=C isomers, but in the dark at 25C 99:1 equilibrium mixtures are reestablished. For 12k 12t, H = 18.8 0.3 kcal/mol and S = 0.5 1.1 eu. Reaction of 13t with Li(C2H5)3BD gives a (77 1):(23 1) mixture of (5-C5H5)Re(NO)(PMe3)(CHDC 6H5) diastereomers. 1984 American Chemical Society.

published proceedings

  • ORGANOMETALLICS

author list (cited authors)

  • KIEL, W. A., BUHRO, W. E., & GLADYSZ, J. A.

citation count

  • 28

complete list of authors

  • KIEL, WA||BUHRO, WE||GLADYSZ, JA

publication date

  • June 1984