TY - JOUR
T1 - Restricted rotation about the arene-iron bond in (arene)Fe(CO)(SiCl3)2 complexes
AU - Hansen, Valerie M.
AU - Batchelor, Raymond J.
AU - Einstein, Frederick W.B.
AU - Male, Jonathan L.
AU - Pomeroy, Roland K.
AU - Zaworotko, Michael J.
PY - 1997/10/28
Y1 - 1997/10/28
N2 - Complexes of formula (η6-C6H6-x-Rx)Fe(CO)(SiCl 3)2 have been prepared from the reaction of Fe(CO)4(SiCl3)2 and the appropriate arene at 210 °C. The characterization of the complexes included the crystal structures of the 1,4-C6H4Pr2i and C6Me6 derivatives. As ascertained by variable-temperature 1H NMR spectroscopy, the (η6-1,4-C6H4R2)Fe(CO)(SiCl 3)2 (R=Me, Et, Pri) compounds exhibit restricted rotation of the arene ring about the iron atom. Lineshape analyses of the NMR spectra reveal the barriers to the rotation in the three compounds are approximately the same (ΔG‡298=9.6-10.8 kcal mol-1). This finding is rationalized in terms of gearing of the R and SiCl3 groups with the rotation. The 1,3,5-C6H3Me3 and C6Me6 derivatives do not show restricted rotation of the arene ring by 1H NMR spectroscopy to -120 °C. It is concluded from these observations that both ground-state and transitionstate effects are important in determining the barrier to rotation of the arene ring in organometallic molecules.
AB - Complexes of formula (η6-C6H6-x-Rx)Fe(CO)(SiCl 3)2 have been prepared from the reaction of Fe(CO)4(SiCl3)2 and the appropriate arene at 210 °C. The characterization of the complexes included the crystal structures of the 1,4-C6H4Pr2i and C6Me6 derivatives. As ascertained by variable-temperature 1H NMR spectroscopy, the (η6-1,4-C6H4R2)Fe(CO)(SiCl 3)2 (R=Me, Et, Pri) compounds exhibit restricted rotation of the arene ring about the iron atom. Lineshape analyses of the NMR spectra reveal the barriers to the rotation in the three compounds are approximately the same (ΔG‡298=9.6-10.8 kcal mol-1). This finding is rationalized in terms of gearing of the R and SiCl3 groups with the rotation. The 1,3,5-C6H3Me3 and C6Me6 derivatives do not show restricted rotation of the arene ring by 1H NMR spectroscopy to -120 °C. It is concluded from these observations that both ground-state and transitionstate effects are important in determining the barrier to rotation of the arene ring in organometallic molecules.
UR - http://www.scopus.com/inward/record.url?scp=0011053504&partnerID=8YFLogxK
U2 - 10.1021/om970021a
DO - 10.1021/om970021a
M3 - Article
AN - SCOPUS:0011053504
SN - 0276-7333
VL - 16
SP - 4875
EP - 4881
JO - Organometallics
JF - Organometallics
IS - 22
ER -