Metal fragment rotation in triangular metal clusters: H-1, H-2, and C-13 NMR studies of the fluxional behavior of the anion {[Re-3(mu-H)(3)(mu-eta(2)-NC5H4)(CO)(10)](-)}
Articolo
Data di Pubblicazione:
1997
Citazione:
Metal fragment rotation in triangular metal clusters: H-1, H-2, and C-13
NMR studies of the fluxional behavior of the anion
{[Re-3(mu-H)(3)(mu-eta(2)-NC5H4)(CO)(10)](-)} / T. Beringhelli, G. D'Alfonso, M. Freni, M. Panigati. - In: ORGANOMETALLICS. - ISSN 0276-7333. - 16:12(1997), pp. 2719-2725.
Abstract:
Variable-temperature C-13 NMR spectroscopy, 1D SPT, and 2D EXSY
experiments have been used to investigate the fluxionality of the
triangular cluster anion {[Re-3(mu-H)(3)(mu-eta(2)-NC5H4)(CO)(10)](-).
The (CO)-C-13 resonances have been assigned through H-1-C-13 2D HMQC and
C-13 2D DQF-COSY experiments and through the measurement of the
(CO)-C-13 longitudinal relaxation times. The exchange pattern observed
in the C-13 2D EXSY experiments proved the occurrence of a synchronous
axial-axial and equatorial-equatorial carbonyl exchange on the apical
metal. The rate constants at 303 and 313 K compare well with those
previously measured, through H-1 NMR spectroscopy, for the exchange of
the two hydrides bridging the lateral edges of the cluster. The rigid
rotation of the whole apical [H2Re(CO)(4)] moiety around an axis
passing through the midpoint of the basal bimetallic fragment is in
agreement with these results. A deuterium kinetic isotope effect
k(H)/k(D) = 1.45(24) has been measured through H-1 and H-2 2D EXSY
experiments, supporting the involvement of the hydrides in the
rate-determining step of the exchange process.}
Tipologia IRIS:
01 - Articolo su periodico
Elenco autori:
T. Beringhelli, G. D'Alfonso, M. Freni, M. Panigati
Link alla scheda completa: