The gas-phase structure of chloroferrocene from microwave spectra

Drouin, Brian J.; Dannemiller, Jennifer J.; Kukolich, Stephen G.

doi:10.1063/1.480708

Cited by 16 publications

(12 citation statements)

References 12 publications

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“…All minima have an eclipsed ring configuration. Though experimentally determined structures are not available for 12 − 14 , a recent gas-phase structure of chloroferrocene reveals an eclipsed conformation (also in agreement with molecular mechanics calculation). In the sense that ferrocenes may be regarded as “three-dimensional arenes”, it may be noted that the gas-phase structures of ethylbenzene and isopropylbenzene have methyl and hydrogen perpendicular and parallel to the ring plane, respectively, 21a,b in contrast to 2 and 13 .…”

Section: Resultssupporting

confidence: 67%

Conformational Properties of Substituted Ferrocenes: Experimental and Theoretical Studies of the Molecular Structures of 1,1‘-Di-tert-butylferrocene and Isopropylferrocene

Morrison¹,

Bone²,

Rankin³

et al. 2001

Organometallics

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The molecular structures of 1,1′-di-tert-butylferrocene (1) and isopropylferrocene (2) have been examined by solid-state X-ray crystallography, gas-phase electron diffraction, and DFT and molecular mechanics calculations. Whereas the solid-state structure of 1 has crystallographically imposed staggered C 2h symmetry, electron diffraction and calculations support a mixture of C 2 eclipsed isomers. The eclipsed ring-ring and the ring-isopropyl conformations found for 2 are essentially identical in the solid and gas phase and are supported by calculations. The molecular mechanics analysis may be extended to other alkylferrocene derivatives.

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Section: Resultssupporting

confidence: 67%

Conformational Properties of Substituted Ferrocenes: Experimental and Theoretical Studies of the Molecular Structures of 1,1‘-Di-tert-butylferrocene and Isopropylferrocene

Morrison¹,

Bone²,

Rankin³

et al. 2001

Organometallics

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“…We first assumed C 2 v symmetry for the vibrationally averaged structure. Second, studies of similar complexes have shown that the cyclopentadienyl rings deviate very little from planarity. − Thus, we have constrained the C 5 H 5 rings to be planar in the analysis. Also, the Cp carbon−hydrogen bond distance, r (C−H), was fixed at 1.077 Å, which was the average value from the DFT calculations and was in agreement with the average value from a neutron diffraction study of the (C 5 H 5 ) 2 MoH 2 complex .…”

Section: Discussionmentioning

confidence: 99%

Microwave Spectra and Gas-Phase Structural Parameters of Bis(η⁵-cyclopentadienyl)tungsten Dihydride

et al. 2007

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Microwave spectra for 11 isotopomers of bis(η 5 -cyclopentadienyl)tungsten dihydride ((C 5 H 5 ) 2 WH 2 ) were recorded in the 5-14 GHz region using a Flygare-Balle-type pulsed beam spectrometer. Spectra arising from four tungsten isotopomers of both the (C 5 H 5 ) 2 WH 2 and (C 5 H 5 ) 2 WHD species and three W isotopomers for the (C 5 H 5 ) 2 WD 2 complex have been measured. The ∼250 b-type transition frequencies assigned for these near-prolate asymmetric top molecules were accurately described (σ fit ) 2-4 kHz) using the rotational parameters A, B, and C and one centrifugal distortion constant, ∆ J . The small value obtained for ∆ J indicates a fairly rigid structure. From a least-squares fit using the resulting 33 rotational constants to obtain the molecular structure, we were able to determine the W-H bond length, r(W-H) ) 1.703(2) Å, the H-W-H bond angle, ∠(H-W-H) ) 78.0(12)°, the W-Cp centroid distance, r(W-Cp) ) 1.940(8) Å, the angle made by the Cp centroids with tungsten, ∠(Cp-W-Cp) ) 155(2)°, and the average C-C bond length, r(C-C) ) 1.429(8) Å. The hydrogen atom separation is r(H-H) ) 2.14(2) Å, indicating that this is clearly a "classical dihydride" rather than an "η 2 -dihydrogen" complex. The WH 2 moiety parameters determined from Kraitchman's equations (r(W-H) ) 1.682(2) Å, ∠(H-W-H) ) 78.6(2), r(H-H) ) 2.130(2) Å) agree well with the least-squares results. Furthermore, the r e parameters obtained from DFT calculations agree well with the experimental r 0 structural parameters. To our knowledge, this work marks the first microwave study of a bent-metallocene complex. The present measurements were made with a pulsed-beam Fourier transform spectrometer employing a homodynetype detection system, and this configuration is described. This homodyne system greatly simplifies the microwave circuit, with no apparent loss in sensitivity.

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“…However, the monosubstituted derivatives are often difficult to crystalize, and for the 1,1‘-disubstituted derivatives, only one structural isomer has been observed in previous solid-state measurements. In the gas phase, monosubstituted derivatives are readily studied, − and multiple conformations of complexes have been observed …”

Section: Introductionmentioning

confidence: 99%

Microwave Spectroscopy Measurements of Rotational Spectra and DFT Calculations for Two Distinct Structural Isomers of 1,1‘-Dimethylferrocene

2003

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Microwave spectra were obtained for two distinct structural isomers of 1,1'-dimethylferrocene, an eclipsed synperiplanar isomer (phi = 0 degrees, the E0 isomer), with A = 1176.9003(2) MHz, B = 898.3343(2) MHz, C = 668.7469(2) MHz, and an eclipsed synclinal isomer (phi = 72 degrees, the E72 isomer) with A = 1208.7117(14) MHz, B = 806.4101(12) MHz, and C = 718.7179(8) MHz. The b-dipole, asymmetric-top spectra of both structural isomers were measured in the frequency range of 5-12 GHz using a Flygare-Balle type of spectrometer. A very good fit to observed transitions, with small distortion constants, was obtained for the E0 conformer, indicating that this conformer is nearly rigid. The deviations obtained in a similar least-squares fit for the E72 confomer are significantly larger, indicating possible fluxional behavior for this conformer. In addition, 7 out of the 26 transitions observed for the E72 isomer conformer clearly exhibit very small splittings, giving further evidence for internal motion. DFT calculations for the different possible conformations of 1,1'- dimethylferrocene arising from rotation of one methyl cyclopentadienyl ligand relative to the other about the nominal C5 axis by an angle phi (dihedral angle) were performed using the B3PW91 functional. The calculations converged and were optimized for five structures on this torsional potential energy surface corresponding to different dihedral angles phi; three yielded energy minima, and two gave energy maxima, corresponding to transition states. The experimental results are in very good agreement with the results of the DFT calculations.

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The gas-phase structure of chloroferrocene from microwave spectra

Abstract: Articles you may be interested inRotational spectra of rare isotopic species of fluoroiodomethane: Determination of the equilibrium structure from rotational spectroscopy and quantum-chemical calculations

Cited by 16 publications

References 12 publications

Conformational Properties of Substituted Ferrocenes: Experimental and Theoretical Studies of the Molecular Structures of 1,1‘-Di-tert-butylferrocene and Isopropylferrocene

Conformational Properties of Substituted Ferrocenes: Experimental and Theoretical Studies of the Molecular Structures of 1,1‘-Di-tert-butylferrocene and Isopropylferrocene

Microwave Spectra and Gas-Phase Structural Parameters of Bis(η⁵-cyclopentadienyl)tungsten Dihydride

Microwave Spectroscopy Measurements of Rotational Spectra and DFT Calculations for Two Distinct Structural Isomers of 1,1‘-Dimethylferrocene

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The gas-phase structure of chloroferrocene from microwave spectra

Abstract: Articles you may be interested inRotational spectra of rare isotopic species of fluoroiodomethane: Determination of the equilibrium structure from rotational spectroscopy and quantum-chemical calculations

Cited by 16 publications

References 12 publications

Conformational Properties of Substituted Ferrocenes: Experimental and Theoretical Studies of the Molecular Structures of 1,1‘-Di-tert-butylferrocene and Isopropylferrocene

Conformational Properties of Substituted Ferrocenes: Experimental and Theoretical Studies of the Molecular Structures of 1,1‘-Di-tert-butylferrocene and Isopropylferrocene

Microwave Spectra and Gas-Phase Structural Parameters of Bis(η5-cyclopentadienyl)tungsten Dihydride

Microwave Spectroscopy Measurements of Rotational Spectra and DFT Calculations for Two Distinct Structural Isomers of 1,1‘-Dimethylferrocene

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Microwave Spectra and Gas-Phase Structural Parameters of Bis(η⁵-cyclopentadienyl)tungsten Dihydride