Molecular structure of tetracarbonyldihydroiron: Microwave measurements and density functional theory calculations

Brian J. Drouin, Stephen G Kukolich

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Microwave spectra of seven isotopomers of tetracarbonyldihydroiron were measured in the 4-16 GHz range using a Flygare-Balle type microwave spectrometer. Measured transitions were fit using a rigid rotor Hamiltonian with five independent distortion constants. Structural parameters from a least-squares fit to the rotational constants are r(Fe-H) = 1.576(64) Å, r(Fe-C1) = 1.815(54) Å, r(Fe-C3 = 1.818(65) Å, r(C1-O1) = 1.123(80) Å, r(C3-O3) = 1.141(74) Å, <(H-Fe-H) 88.0(2.8)°, <(C1-Fe-C2) = 154.2(4.2)°, <(C3-Fe-C4) = 99.4(4.3)°, <(Fe-C1-O1) = 172.5(5.6)°, and <(Fe-C3-O3) 177.8(6.8)°. All of the carbonyl groups are bent slightly toward the hydrogen atoms. The least-squares-determined structural parameters are in excellent agreement with the substitution coordinates determined from the Kraitchman equations, the structural parameters calculated using density functional theory, and the previously published electron diffraction data. The C(2v) molecular symmetry is consistent with the results ofthe microwave data and with theoretical calculations. All of the analyses show that the H atoms are separated by about 2.2 Å, and this indicates that the complex is clearly a 'classical dihydride' rather than an η2-'dihydrogen' complex. Structural parameters obtained from a density functional theory calculation agreed with measured values to within 2%. The density functional theory analysis of the anharmonicity in the Fe-H symmetric stretching potential is shown to support the observed deuterium isotope effects observed for the hydrogen atom coordinates. The anharmonicity effects are larger for the Fe-H stretching coordinate than for the <H-Fe-H interbond angle. The r0(Fe-D) bond lengths were observed to be 0.05(4) Å shorter than the r0(Fe-H) bond lengths.

Original languageEnglish (US)
Pages (from-to)6774-6780
Number of pages7
JournalJournal of the American Chemical Society
Volume120
Issue number27
DOIs
StatePublished - Jul 15 1998

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Microwave measurement
Microwaves
Molecular Structure
Molecular structure
Density functional theory
Bond length
Least-Squares Analysis
Atoms
Stretching
Hydrogen
Microwave spectrometers
Rigid rotors
Hamiltonians
Deuterium
Electron diffraction
Isotopes
Substitution reactions
Electrons

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Molecular structure of tetracarbonyldihydroiron : Microwave measurements and density functional theory calculations. / Drouin, Brian J.; Kukolich, Stephen G.

In: Journal of the American Chemical Society, Vol. 120, No. 27, 15.07.1998, p. 6774-6780.

Research output: Contribution to journalArticle

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title = "Molecular structure of tetracarbonyldihydroiron: Microwave measurements and density functional theory calculations",
abstract = "Microwave spectra of seven isotopomers of tetracarbonyldihydroiron were measured in the 4-16 GHz range using a Flygare-Balle type microwave spectrometer. Measured transitions were fit using a rigid rotor Hamiltonian with five independent distortion constants. Structural parameters from a least-squares fit to the rotational constants are r(Fe-H) = 1.576(64) {\AA}, r(Fe-C1) = 1.815(54) {\AA}, r(Fe-C3 = 1.818(65) {\AA}, r(C1-O1) = 1.123(80) {\AA}, r(C3-O3) = 1.141(74) {\AA}, <(H-Fe-H) 88.0(2.8)°, <(C1-Fe-C2) = 154.2(4.2)°, <(C3-Fe-C4) = 99.4(4.3)°, <(Fe-C1-O1) = 172.5(5.6)°, and <(Fe-C3-O3) 177.8(6.8)°. All of the carbonyl groups are bent slightly toward the hydrogen atoms. The least-squares-determined structural parameters are in excellent agreement with the substitution coordinates determined from the Kraitchman equations, the structural parameters calculated using density functional theory, and the previously published electron diffraction data. The C(2v) molecular symmetry is consistent with the results ofthe microwave data and with theoretical calculations. All of the analyses show that the H atoms are separated by about 2.2 {\AA}, and this indicates that the complex is clearly a 'classical dihydride' rather than an η2-'dihydrogen' complex. Structural parameters obtained from a density functional theory calculation agreed with measured values to within 2{\%}. The density functional theory analysis of the anharmonicity in the Fe-H symmetric stretching potential is shown to support the observed deuterium isotope effects observed for the hydrogen atom coordinates. The anharmonicity effects are larger for the Fe-H stretching coordinate than for the <H-Fe-H interbond angle. The r0(Fe-D) bond lengths were observed to be 0.05(4) {\AA} shorter than the r0(Fe-H) bond lengths.",
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T1 - Molecular structure of tetracarbonyldihydroiron

T2 - Microwave measurements and density functional theory calculations

AU - Drouin, Brian J.

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N2 - Microwave spectra of seven isotopomers of tetracarbonyldihydroiron were measured in the 4-16 GHz range using a Flygare-Balle type microwave spectrometer. Measured transitions were fit using a rigid rotor Hamiltonian with five independent distortion constants. Structural parameters from a least-squares fit to the rotational constants are r(Fe-H) = 1.576(64) Å, r(Fe-C1) = 1.815(54) Å, r(Fe-C3 = 1.818(65) Å, r(C1-O1) = 1.123(80) Å, r(C3-O3) = 1.141(74) Å, <(H-Fe-H) 88.0(2.8)°, <(C1-Fe-C2) = 154.2(4.2)°, <(C3-Fe-C4) = 99.4(4.3)°, <(Fe-C1-O1) = 172.5(5.6)°, and <(Fe-C3-O3) 177.8(6.8)°. All of the carbonyl groups are bent slightly toward the hydrogen atoms. The least-squares-determined structural parameters are in excellent agreement with the substitution coordinates determined from the Kraitchman equations, the structural parameters calculated using density functional theory, and the previously published electron diffraction data. The C(2v) molecular symmetry is consistent with the results ofthe microwave data and with theoretical calculations. All of the analyses show that the H atoms are separated by about 2.2 Å, and this indicates that the complex is clearly a 'classical dihydride' rather than an η2-'dihydrogen' complex. Structural parameters obtained from a density functional theory calculation agreed with measured values to within 2%. The density functional theory analysis of the anharmonicity in the Fe-H symmetric stretching potential is shown to support the observed deuterium isotope effects observed for the hydrogen atom coordinates. The anharmonicity effects are larger for the Fe-H stretching coordinate than for the <H-Fe-H interbond angle. The r0(Fe-D) bond lengths were observed to be 0.05(4) Å shorter than the r0(Fe-H) bond lengths.

AB - Microwave spectra of seven isotopomers of tetracarbonyldihydroiron were measured in the 4-16 GHz range using a Flygare-Balle type microwave spectrometer. Measured transitions were fit using a rigid rotor Hamiltonian with five independent distortion constants. Structural parameters from a least-squares fit to the rotational constants are r(Fe-H) = 1.576(64) Å, r(Fe-C1) = 1.815(54) Å, r(Fe-C3 = 1.818(65) Å, r(C1-O1) = 1.123(80) Å, r(C3-O3) = 1.141(74) Å, <(H-Fe-H) 88.0(2.8)°, <(C1-Fe-C2) = 154.2(4.2)°, <(C3-Fe-C4) = 99.4(4.3)°, <(Fe-C1-O1) = 172.5(5.6)°, and <(Fe-C3-O3) 177.8(6.8)°. All of the carbonyl groups are bent slightly toward the hydrogen atoms. The least-squares-determined structural parameters are in excellent agreement with the substitution coordinates determined from the Kraitchman equations, the structural parameters calculated using density functional theory, and the previously published electron diffraction data. The C(2v) molecular symmetry is consistent with the results ofthe microwave data and with theoretical calculations. All of the analyses show that the H atoms are separated by about 2.2 Å, and this indicates that the complex is clearly a 'classical dihydride' rather than an η2-'dihydrogen' complex. Structural parameters obtained from a density functional theory calculation agreed with measured values to within 2%. The density functional theory analysis of the anharmonicity in the Fe-H symmetric stretching potential is shown to support the observed deuterium isotope effects observed for the hydrogen atom coordinates. The anharmonicity effects are larger for the Fe-H stretching coordinate than for the <H-Fe-H interbond angle. The r0(Fe-D) bond lengths were observed to be 0.05(4) Å shorter than the r0(Fe-H) bond lengths.

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