Multisite magnetization transfer studies of metal migration in (eta(3)-C7H7)Re(CO)(4), (eta(3)-C7H7)Os(CO)(3)SnPh3, (eta(3)-C7H7)Re(CO)(3)PMe3, (eta(5)-C7H7)Re(CO)(3), (eta(5)-C7H7)Fe(CO)(2)SnPh3, (eta(5)-C7H7)OS(CO)(2)SnPh3, and (eta(5)-C7H7)Ru(CO)(2)SnPh3

TY - JOUR

T1 - Multisite magnetization transfer studies of metal migration in (eta(3)-C7H7)Re(CO)(4), (eta(3)-C7H7)Os(CO)(3)SnPh3, (eta(3)-C7H7)Re(CO)(3)PMe3, (eta(5)-C7H7)Re(CO)(3), (eta(5)-C7H7)Fe(CO)(2)SnPh3, (eta(5)-C7H7)OS(CO)(2)SnPh3, and (eta(5)-C7H7)Ru(CO)(2)SnPh3

AU - Muhandiram, D R

AU - Kiel, G Y

AU - Aarts, G H M

AU - Saez, I M

AU - Reuvers, J G A

AU - Heinekey, D M

AU - Graham, W A G

AU - Takats, J

AU - McClung, R E D

PY - 2002/6/24

Y1 - 2002/6/24

N2 - Multisite magnetization transfer (MMT) studies of metal migration around the C7H7 rings in (eta(3)-C7H7)Re(CO)(4) (1), (eta(3)-C7H7)Os(CO)(3)SnPh3 (2), (eta(3)-C7H7)Re(CO)(3)PMe3 (3), (eta(5)-C7H7)Re(CO)(3) (4), (eta(5)-C7H7)Fe(CO)(2)SnPh3 (5), (eta(5)-C7H7)OS(CO)(2)SnPh3 (6), and (eta(5)-C7H7)Ru(CO)(2)SnPh3 (7) are reported. The possible presence of 1,2-, 1,3-, and/or 1,4-metal shifts in the ring fluxionality was investigated in all compounds, and it was shown that both 1,2- and 1,3-shifts occur concurrently in 5 and 6, but that only 1,2-shifts occur in 1, 2, 3, and 4, and only 1,3-shifts in 7. Several of the compounds exist as mixtures of isomers, and the application of MMT was crucial in unraveling the fluxionality of one isomer in the presence of the other. Thus, MMT experiments allowed the study of the rate of metal migration in the symmetric isomer of 2, which occurs in the presence of more rapid exchange in the asymmetric isomer. The symmetric isomer of 3 was found to exchange faster than the asymmetric isomer. MMT study of the exchange between symmetric and asymmetric isomers of 7 at low temperatures showed that the two enantiomers of the asymmetric isomer exchange directly with the symmetric isomer, but not with each other. MMT experiments allowed the study of metal migration in 7 in the presence of the isomer interchange process. The rate constants and free energies of activation for the metal shifts and for the isomer interchange are reported. It was concluded that orbital symmetry considerations do not provide useful predictions about the mechanisms of metal migration in compounds containing eta(1)-,eta(3)-, or eta(5)-C7H7 rings.

AB - Multisite magnetization transfer (MMT) studies of metal migration around the C7H7 rings in (eta(3)-C7H7)Re(CO)(4) (1), (eta(3)-C7H7)Os(CO)(3)SnPh3 (2), (eta(3)-C7H7)Re(CO)(3)PMe3 (3), (eta(5)-C7H7)Re(CO)(3) (4), (eta(5)-C7H7)Fe(CO)(2)SnPh3 (5), (eta(5)-C7H7)OS(CO)(2)SnPh3 (6), and (eta(5)-C7H7)Ru(CO)(2)SnPh3 (7) are reported. The possible presence of 1,2-, 1,3-, and/or 1,4-metal shifts in the ring fluxionality was investigated in all compounds, and it was shown that both 1,2- and 1,3-shifts occur concurrently in 5 and 6, but that only 1,2-shifts occur in 1, 2, 3, and 4, and only 1,3-shifts in 7. Several of the compounds exist as mixtures of isomers, and the application of MMT was crucial in unraveling the fluxionality of one isomer in the presence of the other. Thus, MMT experiments allowed the study of the rate of metal migration in the symmetric isomer of 2, which occurs in the presence of more rapid exchange in the asymmetric isomer. The symmetric isomer of 3 was found to exchange faster than the asymmetric isomer. MMT study of the exchange between symmetric and asymmetric isomers of 7 at low temperatures showed that the two enantiomers of the asymmetric isomer exchange directly with the symmetric isomer, but not with each other. MMT experiments allowed the study of metal migration in 7 in the presence of the isomer interchange process. The rate constants and free energies of activation for the metal shifts and for the isomer interchange are reported. It was concluded that orbital symmetry considerations do not provide useful predictions about the mechanisms of metal migration in compounds containing eta(1)-,eta(3)-, or eta(5)-C7H7 rings.

KW - X-RAY STRUCTURE

KW - SELECTIVE-INVERSION EXPERIMENTS

KW - SLOW CHEMICAL-EXCHANGE

KW - LEAST-SQUARES ANALYSIS

KW - COUPLED SPIN SYSTEMS

KW - N = 1

KW - FLUXIONAL BEHAVIOR

KW - CRYSTAL-STRUCTURE

KW - ROTATIONAL BARRIERS

KW - HAPTOTROPIC SHIFTS

U2 - 10.1021/om011061o

DO - 10.1021/om011061o

M3 - Article

SN - 0276-7333

VL - 21

SP - 2687

EP - 2704

JO - Organometallics

JF - Organometallics

IS - 13

ER -