Restricted rotation about the arene-iron bond in (arene)Fe(CO)(SiCl3)2 complexes

Valerie M. Hansen; Raymond J. Batchelor; Frederick W.B. Einstein; Jonathan L. Male; Roland K. Pomeroy; Michael J. Zaworotko

doi:10.1021/om970021a

Restricted rotation about the arene-iron bond in (arene)Fe(CO)(SiCl₃)₂ complexes

Valerie M. Hansen
, Raymond J. Batchelor
, Frederick W.B. Einstein
, Jonathan L. Male
, Roland K. Pomeroy
, Michael J. Zaworotko

Research output: Contribution to journal › Article › peer-review

Abstract

Complexes of formula (η⁶-C₆H_6-x-R_x)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.

Original language	English
Pages (from-to)	4875-4881
Number of pages	7
Journal	Organometallics
Volume	16
Issue number	22
DOIs	https://doi.org/10.1021/om970021a
Publication status	Published - 28 Oct 1997
Externally published	Yes

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@article{64b6c7bed5ae4b0282d78d4860986d67,

title = "Restricted rotation about the arene-iron bond in (arene)Fe(CO)(SiCl3)2 complexes",

abstract = "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.",

author = "Hansen, \{Valerie M.\} and Batchelor, \{Raymond J.\} and Einstein, \{Frederick W.B.\} and Male, \{Jonathan L.\} and Pomeroy, \{Roland K.\} and Zaworotko, \{Michael J.\}",

year = "1997",

month = oct,

day = "28",

doi = "10.1021/om970021a",

language = "English",

volume = "16",

pages = "4875--4881",

journal = "Organometallics",

issn = "0276-7333",

number = "22",

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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 - https://www.scopus.com/pages/publications/0011053504

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 -

Restricted rotation about the arene-iron bond in (arene)Fe(CO)(SiCl₃)₂ complexes

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