1,3-ditungstacyclobutadienes. 2. the Synthesis of Alkoxide Derivatives of W2(μ-csime3)2(ch2sime3)4 and Investigations of the Electronic Structures of the M2(μ-csime3)2 core as a Function of Dn-dninteractions (n = 0, M = Ta; N = 1, M = W; N = 2, M = Re)

Malcolm H. Chisholm; Joseph A. Heppert; Edward M. Kober; Dennis L. Lichtenberger

doi:10.1021/om00148a026

1,3-ditungstacyclobutadienes. 2. the Synthesis of Alkoxide Derivatives of W₂(μ-csime₃)₂(ch₂sime₃)₄ and Investigations of the Electronic Structures of the M₂(μ-csime₃)₂ core as a Function of Dⁿ-dⁿinteractions (n = 0, M = Ta; N = 1, M = W; N = 2, M = Re)

Malcolm H. Chisholm, Joseph A. Heppert, Edward M. Kober, Dennis L. Lichtenberger

Research and Innovation

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Abstract

W₂(μ-CSiMe₃)₂(CH₂SiMe₃)₄(I) reacts with t-BuOH in alkane solvents to produce a mixture of two isomers of W₂(μ-CSiMe)₂(O-t-Bu)₂(CH₂SiMe₃)₂from which the minor isomer can be isolated by fractional crystallization. the electronic structures of several related dimetallacyclobutadiene derivatives have been investigated by UV photoelectron spectroscopy, UV/visible spectrophotometry, and MO calculations. the M-M bonding configurations for the M₂(μ-CSiMe₃)₂(CH₂SiMe₃)₄molecules have been determined as σ°δ*°, σ²δ*⁰, and σ²δ*²for M = Ta, W, and Re, respectively, by EHMO and Fenske-Hall MO calculations. This result is better reconciled with the previously observed M-M distances—Nb₂> Re₂> W₂—than with the original proposal of a σ 2 π 2 configuration for the Re derivative. On replacement of the terminal alkyl ligands of the W complex by O-i-Pr ligands, the 2a_uLUMO (W-W δ*) and 2b_2g w- μ -c π bond are strongly destabilized by antibonding interactions with pπ orbitals on oxygen. Destabilizaμon of the 2b_2gorbital results in the appearance of a clearly defined ionization representing this orbital at 7.2 eV in the PE spectrum of W₂(μ-CSiMe₃)₂(0-i-Pr)₄. Mulliken population analyses of the 6ag orbitals of I and W₂(μ-CSiMe₃)₂(0-i-Pr)4 correctly predict that I prefers a shorter W-W distance of 2.54 A, while the alkoxide-substituted compound prefers the longer W-W distance of 2.62 A.

Original language	English
Pages (from-to)	1065-1073
Number of pages	9
Journal	Organometallics
Volume	6
Issue number	5
DOIs	https://doi.org/10.1021/om00148a026
State	Published - May 1 1987

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Chisholm, M. H., Heppert, J. A., Kober, E. M., & Lichtenberger, D. L. (1987). 1,3-ditungstacyclobutadienes. 2. the Synthesis of Alkoxide Derivatives of W₂(μ-csime₃)₂(ch₂sime₃)₄ and Investigations of the Electronic Structures of the M₂(μ-csime₃)₂ core as a Function of Dⁿ-dⁿinteractions (n = 0, M = Ta; N = 1, M = W; N = 2, M = Re). Organometallics, 6(5), 1065-1073. https://doi.org/10.1021/om00148a026

Chisholm, Malcolm H. ; Heppert, Joseph A. ; Kober, Edward M. ; Lichtenberger, Dennis L. / 1,3-ditungstacyclobutadienes. 2. the Synthesis of Alkoxide Derivatives of W₂(μ-csime₃)₂(ch₂sime₃)₄ and Investigations of the Electronic Structures of the M₂(μ-csime₃)₂ core as a Function of Dⁿ-dⁿinteractions (n = 0, M = Ta; N = 1, M = W; N = 2, M = Re). In: Organometallics. 1987 ; Vol. 6, No. 5. pp. 1065-1073.

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title = "1,3-ditungstacyclobutadienes. 2. the Synthesis of Alkoxide Derivatives of W2(μ-csime3)2(ch2sime3)4 and Investigations of the Electronic Structures of the M2(μ-csime3)2 core as a Function of Dn-dninteractions (n = 0, M = Ta; N = 1, M = W; N = 2, M = Re)",

abstract = "W2(μ-CSiMe3)2(CH2SiMe3)4(I) reacts with t-BuOH in alkane solvents to produce a mixture of two isomers of W2(μ-CSiMe)2(O-t-Bu)2(CH2SiMe3)2from which the minor isomer can be isolated by fractional crystallization. the electronic structures of several related dimetallacyclobutadiene derivatives have been investigated by UV photoelectron spectroscopy, UV/visible spectrophotometry, and MO calculations. the M-M bonding configurations for the M2(μ-CSiMe3)2(CH2SiMe3)4molecules have been determined as σ°δ*°, σ2δ*0, and σ2δ*2for M = Ta, W, and Re, respectively, by EHMO and Fenske-Hall MO calculations. This result is better reconciled with the previously observed M-M distances—Nb2> Re2> W2—than with the original proposal of a σ 2 π 2 configuration for the Re derivative. On replacement of the terminal alkyl ligands of the W complex by O-i-Pr ligands, the 2auLUMO (W-W δ*) and 2b2g w- μ -c π bond are strongly destabilized by antibonding interactions with pπ orbitals on oxygen. Destabilizaμon of the 2b2gorbital results in the appearance of a clearly defined ionization representing this orbital at 7.2 eV in the PE spectrum of W2(μ-CSiMe3)2(0-i-Pr)4. Mulliken population analyses of the 6ag orbitals of I and W2(μ-CSiMe3)2(0-i-Pr)4 correctly predict that I prefers a shorter W-W distance of 2.54 A, while the alkoxide-substituted compound prefers the longer W-W distance of 2.62 A.",

author = "Chisholm, {Malcolm H.} and Heppert, {Joseph A.} and Kober, {Edward M.} and Lichtenberger, {Dennis L.}",

year = "1987",

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Chisholm, MH, Heppert, JA, Kober, EM & Lichtenberger, DL 1987, '1,3-ditungstacyclobutadienes. 2. the Synthesis of Alkoxide Derivatives of W₂(μ-csime₃)₂(ch₂sime₃)₄ and Investigations of the Electronic Structures of the M₂(μ-csime₃)₂ core as a Function of Dⁿ-dⁿinteractions (n = 0, M = Ta; N = 1, M = W; N = 2, M = Re)', Organometallics, vol. 6, no. 5, pp. 1065-1073. https://doi.org/10.1021/om00148a026

1,3-ditungstacyclobutadienes. 2. the Synthesis of Alkoxide Derivatives of W₂(μ-csime₃)₂(ch₂sime₃)₄ and Investigations of the Electronic Structures of the M₂(μ-csime₃)₂ core as a Function of Dⁿ-dⁿinteractions (n = 0, M = Ta; N = 1, M = W; N = 2, M = Re). / Chisholm, Malcolm H.; Heppert, Joseph A.; Kober, Edward M.; Lichtenberger, Dennis L.

In: Organometallics, Vol. 6, No. 5, 01.05.1987, p. 1065-1073.

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

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T1 - 1,3-ditungstacyclobutadienes. 2. the Synthesis of Alkoxide Derivatives of W2(μ-csime3)2(ch2sime3)4 and Investigations of the Electronic Structures of the M2(μ-csime3)2 core as a Function of Dn-dninteractions (n = 0, M = Ta; N = 1, M = W; N = 2, M = Re)

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AU - Lichtenberger, Dennis L.

PY - 1987/5/1

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N2 - W2(μ-CSiMe3)2(CH2SiMe3)4(I) reacts with t-BuOH in alkane solvents to produce a mixture of two isomers of W2(μ-CSiMe)2(O-t-Bu)2(CH2SiMe3)2from which the minor isomer can be isolated by fractional crystallization. the electronic structures of several related dimetallacyclobutadiene derivatives have been investigated by UV photoelectron spectroscopy, UV/visible spectrophotometry, and MO calculations. the M-M bonding configurations for the M2(μ-CSiMe3)2(CH2SiMe3)4molecules have been determined as σ°δ*°, σ2δ*0, and σ2δ*2for M = Ta, W, and Re, respectively, by EHMO and Fenske-Hall MO calculations. This result is better reconciled with the previously observed M-M distances—Nb2> Re2> W2—than with the original proposal of a σ 2 π 2 configuration for the Re derivative. On replacement of the terminal alkyl ligands of the W complex by O-i-Pr ligands, the 2auLUMO (W-W δ*) and 2b2g w- μ -c π bond are strongly destabilized by antibonding interactions with pπ orbitals on oxygen. Destabilizaμon of the 2b2gorbital results in the appearance of a clearly defined ionization representing this orbital at 7.2 eV in the PE spectrum of W2(μ-CSiMe3)2(0-i-Pr)4. Mulliken population analyses of the 6ag orbitals of I and W2(μ-CSiMe3)2(0-i-Pr)4 correctly predict that I prefers a shorter W-W distance of 2.54 A, while the alkoxide-substituted compound prefers the longer W-W distance of 2.62 A.

AB - W2(μ-CSiMe3)2(CH2SiMe3)4(I) reacts with t-BuOH in alkane solvents to produce a mixture of two isomers of W2(μ-CSiMe)2(O-t-Bu)2(CH2SiMe3)2from which the minor isomer can be isolated by fractional crystallization. the electronic structures of several related dimetallacyclobutadiene derivatives have been investigated by UV photoelectron spectroscopy, UV/visible spectrophotometry, and MO calculations. the M-M bonding configurations for the M2(μ-CSiMe3)2(CH2SiMe3)4molecules have been determined as σ°δ*°, σ2δ*0, and σ2δ*2for M = Ta, W, and Re, respectively, by EHMO and Fenske-Hall MO calculations. This result is better reconciled with the previously observed M-M distances—Nb2> Re2> W2—than with the original proposal of a σ 2 π 2 configuration for the Re derivative. On replacement of the terminal alkyl ligands of the W complex by O-i-Pr ligands, the 2auLUMO (W-W δ*) and 2b2g w- μ -c π bond are strongly destabilized by antibonding interactions with pπ orbitals on oxygen. Destabilizaμon of the 2b2gorbital results in the appearance of a clearly defined ionization representing this orbital at 7.2 eV in the PE spectrum of W2(μ-CSiMe3)2(0-i-Pr)4. Mulliken population analyses of the 6ag orbitals of I and W2(μ-CSiMe3)2(0-i-Pr)4 correctly predict that I prefers a shorter W-W distance of 2.54 A, while the alkoxide-substituted compound prefers the longer W-W distance of 2.62 A.

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Chisholm MH, Heppert JA, Kober EM, Lichtenberger DL. 1,3-ditungstacyclobutadienes. 2. the Synthesis of Alkoxide Derivatives of W₂(μ-csime₃)₂(ch₂sime₃)₄ and Investigations of the Electronic Structures of the M₂(μ-csime₃)₂ core as a Function of Dⁿ-dⁿinteractions (n = 0, M = Ta; N = 1, M = W; N = 2, M = Re). Organometallics. 1987 May 1;6(5):1065-1073. https://doi.org/10.1021/om00148a026