Equilibrium studies on metalmetal bond dissociation in the [(C5Me5)Cr(CO)3]2 dimer by use of NMR spectroscopy

Lai Yoong Goh; S. K. Khoo; Y. Y. Lim

doi:10.1016/0022-328X(90)80089-I

Equilibrium studies on metalmetal bond dissociation in the [(C₅Me₅)Cr(CO)₃]₂ dimer by use of NMR spectroscopy

Lai Yoong Goh
, S. K. Khoo
, Y. Y. Lim

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

21 Citations (Scopus)

Abstract

The thermodynamics of metalmetal bond dissociation in the [(C₅Me₅)Cr(CO)₃]₂ dimer was studied by variable-temperature room NMR study in toluene-d₈. Dissociation constants and proton isotropic shifts at various temperatures were obtained. Application of the van ′ Hoff equation gives the following thermodynamic parameters: ΔH = 18.3 (±0.6) kcal mol^-1; ΔS = 54.8 (±2.2) cal mol^-1 K^-1 (ΔG = 1.9 kcal mol^-1 at 300 K). These parameters were compared with those of the [(C₅H₅)Cr(CO)₃]₂ dimer. The most likely spin delocalization mechanism for the methyl protons is believed to be a combination of σ and π spin delocalization. The ESR spectrum in toluene (g₀ = 2.004±0.001) or at below 273 K is consistent with a non-degenerate ground state of the monomer.

Original language	English
Pages (from-to)	115-123
Number of pages	9
Journal	Journal of Organometallic Chemistry
Volume	399
Issue number	1-2
DOIs	https://doi.org/10.1016/0022-328X(90)80089-I
Publication status	Published - 4 Dec 1990
Externally published	Yes

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@article{dd6f935e3643458187437e5f0dcb7271,

title = "Equilibrium studies on metalmetal bond dissociation in the [(C5Me5)Cr(CO)3]2 dimer by use of NMR spectroscopy",

abstract = "The thermodynamics of metalmetal bond dissociation in the [(C5Me5)Cr(CO)3]2 dimer was studied by variable-temperature room NMR study in toluene-d8. Dissociation constants and proton isotropic shifts at various temperatures were obtained. Application of the van ′ Hoff equation gives the following thermodynamic parameters: ΔH = 18.3 (±0.6) kcal mol-1; ΔS = 54.8 (±2.2) cal mol-1 K-1 (ΔG = 1.9 kcal mol-1 at 300 K). These parameters were compared with those of the [(C5H5)Cr(CO)3]2 dimer. The most likely spin delocalization mechanism for the methyl protons is believed to be a combination of σ and π spin delocalization. The ESR spectrum in toluene (g0 = 2.004±0.001) or at below 273 K is consistent with a non-degenerate ground state of the monomer.",

author = "Goh, \{Lai Yoong\} and Khoo, \{S. K.\} and Lim, \{Y. Y.\}",

note = "Funding Information: The authors acknowledge with thanks IRPA R\&D Grant No. 04-07-04-127 and the financial support from the University of Malaya. They also thank Professor Martyn C.R. Symons for helpful discussions. Copyright: Copyright 2014 Elsevier B.V., All rights reserved.",

year = "1990",

month = dec,

day = "4",

doi = "10.1016/0022-328X(90)80089-I",

language = "English",

volume = "399",

pages = "115--123",

journal = "Journal of Organometallic Chemistry",

issn = "0022-328X",

publisher = "Elsevier BV",

number = "1-2",

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TY - JOUR

T1 - Equilibrium studies on metalmetal bond dissociation in the [(C5Me5)Cr(CO)3]2 dimer by use of NMR spectroscopy

AU - Goh, Lai Yoong

AU - Khoo, S. K.

AU - Lim, Y. Y.

N1 - Funding Information: The authors acknowledge with thanks IRPA R&D Grant No. 04-07-04-127 and the financial support from the University of Malaya. They also thank Professor Martyn C.R. Symons for helpful discussions. Copyright: Copyright 2014 Elsevier B.V., All rights reserved.

PY - 1990/12/4

Y1 - 1990/12/4

N2 - The thermodynamics of metalmetal bond dissociation in the [(C5Me5)Cr(CO)3]2 dimer was studied by variable-temperature room NMR study in toluene-d8. Dissociation constants and proton isotropic shifts at various temperatures were obtained. Application of the van ′ Hoff equation gives the following thermodynamic parameters: ΔH = 18.3 (±0.6) kcal mol-1; ΔS = 54.8 (±2.2) cal mol-1 K-1 (ΔG = 1.9 kcal mol-1 at 300 K). These parameters were compared with those of the [(C5H5)Cr(CO)3]2 dimer. The most likely spin delocalization mechanism for the methyl protons is believed to be a combination of σ and π spin delocalization. The ESR spectrum in toluene (g0 = 2.004±0.001) or at below 273 K is consistent with a non-degenerate ground state of the monomer.

AB - The thermodynamics of metalmetal bond dissociation in the [(C5Me5)Cr(CO)3]2 dimer was studied by variable-temperature room NMR study in toluene-d8. Dissociation constants and proton isotropic shifts at various temperatures were obtained. Application of the van ′ Hoff equation gives the following thermodynamic parameters: ΔH = 18.3 (±0.6) kcal mol-1; ΔS = 54.8 (±2.2) cal mol-1 K-1 (ΔG = 1.9 kcal mol-1 at 300 K). These parameters were compared with those of the [(C5H5)Cr(CO)3]2 dimer. The most likely spin delocalization mechanism for the methyl protons is believed to be a combination of σ and π spin delocalization. The ESR spectrum in toluene (g0 = 2.004±0.001) or at below 273 K is consistent with a non-degenerate ground state of the monomer.

UR - https://www.scopus.com/pages/publications/0000049225

U2 - 10.1016/0022-328X(90)80089-I

DO - 10.1016/0022-328X(90)80089-I

M3 - Article

AN - SCOPUS:0000049225

SN - 0022-328X

VL - 399

SP - 115

EP - 123

JO - Journal of Organometallic Chemistry

JF - Journal of Organometallic Chemistry

IS - 1-2

ER -

Equilibrium studies on metalmetal bond dissociation in the [(C5Me5)Cr(CO)3]2 dimer by use of NMR spectroscopy

Abstract

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Equilibrium studies on metalmetal bond dissociation in the [(C₅Me₅)Cr(CO)₃]₂ dimer by use of NMR spectroscopy