Unusual structure and reactivity of the photogenerated intermediate Cp*Cr(μ-CO)3CrCp* (Cp* = η5-C5Me5)

Ian G. Virrels; Trevor F. Nolan; Michael W. George; James J. Turner

doi:10.1021/om970641b

Unusual structure and reactivity of the photogenerated intermediate CpCr(μ-CO)₃CrCp (Cp* = η⁵-C₅Me₅)

Ian G. Virrels, Trevor F. Nolan, Michael W. George, James J. Turner

Research output: Journal Publication › Article › peer-review

11 Citations (Scopus)

Abstract

Employing time-resolved IR spectroscopy, we have demonstrated that, following photolysis of [Cp*Cr(CO)₂]₂ (D in n-heptane, the only initial photoproduct is the triply bridged CO-loss intermediate Cp*Cr(μ-CO)₃CrCp* (4). Two bridging v(CO) bands are observed, resulting from the splitting of the e′ mode of 4, which leads to the conclusion that the CO bridging groups are asymmetric. The rate of the back reaction of 4 with CO has been measured (k₂ = 5.2 (±0.5) × 10⁷ M^-1 s^-1), and this is 1000 times faster than the rate of the analogous back reaction of CO with CpFe(μ-CO)₃FeCp. Moreover, unlike many CO-loss intermediates, there is no reaction of 4 with PPh₃. The rate of reaction of 4 with THF, to produce Cp*₂Cr₂(CO)₃(THF) (6), has been estimated (k₂ = 1.6 (±0.2) x 10⁸ M^-1 s^-1).

Original language	English
Pages (from-to)	5879-5883
Number of pages	5
Journal	Organometallics
Volume	16
Issue number	26
DOIs	https://doi.org/10.1021/om970641b
Publication status	Published - 23 Dec 1997
Externally published	Yes

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Organic Chemistry
Inorganic Chemistry

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title = "Unusual structure and reactivity of the photogenerated intermediate Cp*Cr(μ-CO)3CrCp* (Cp* = η5-C5Me5)",

abstract = "Employing time-resolved IR spectroscopy, we have demonstrated that, following photolysis of [Cp*Cr(CO)2]2 (D in n-heptane, the only initial photoproduct is the triply bridged CO-loss intermediate Cp*Cr(μ-CO)3CrCp* (4). Two bridging v(CO) bands are observed, resulting from the splitting of the e′ mode of 4, which leads to the conclusion that the CO bridging groups are asymmetric. The rate of the back reaction of 4 with CO has been measured (k2 = 5.2 (±0.5) × 107 M-1 s-1), and this is 1000 times faster than the rate of the analogous back reaction of CO with CpFe(μ-CO)3FeCp. Moreover, unlike many CO-loss intermediates, there is no reaction of 4 with PPh3. The rate of reaction of 4 with THF, to produce Cp*2Cr2(CO)3(THF) (6), has been estimated (k2 = 1.6 (±0.2) x 108 M-1 s-1).",

author = "Virrels, {Ian G.} and Nolan, {Trevor F.} and George, {Michael W.} and Turner, {James J.}",

year = "1997",

month = dec,

day = "23",

doi = "10.1021/om970641b",

language = "English",

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journal = "Organometallics",

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T1 - Unusual structure and reactivity of the photogenerated intermediate Cp*Cr(μ-CO)3CrCp* (Cp* = η5-C5Me5)

AU - Virrels, Ian G.

AU - Nolan, Trevor F.

AU - George, Michael W.

AU - Turner, James J.

PY - 1997/12/23

Y1 - 1997/12/23

N2 - Employing time-resolved IR spectroscopy, we have demonstrated that, following photolysis of [Cp*Cr(CO)2]2 (D in n-heptane, the only initial photoproduct is the triply bridged CO-loss intermediate Cp*Cr(μ-CO)3CrCp* (4). Two bridging v(CO) bands are observed, resulting from the splitting of the e′ mode of 4, which leads to the conclusion that the CO bridging groups are asymmetric. The rate of the back reaction of 4 with CO has been measured (k2 = 5.2 (±0.5) × 107 M-1 s-1), and this is 1000 times faster than the rate of the analogous back reaction of CO with CpFe(μ-CO)3FeCp. Moreover, unlike many CO-loss intermediates, there is no reaction of 4 with PPh3. The rate of reaction of 4 with THF, to produce Cp*2Cr2(CO)3(THF) (6), has been estimated (k2 = 1.6 (±0.2) x 108 M-1 s-1).

AB - Employing time-resolved IR spectroscopy, we have demonstrated that, following photolysis of [Cp*Cr(CO)2]2 (D in n-heptane, the only initial photoproduct is the triply bridged CO-loss intermediate Cp*Cr(μ-CO)3CrCp* (4). Two bridging v(CO) bands are observed, resulting from the splitting of the e′ mode of 4, which leads to the conclusion that the CO bridging groups are asymmetric. The rate of the back reaction of 4 with CO has been measured (k2 = 5.2 (±0.5) × 107 M-1 s-1), and this is 1000 times faster than the rate of the analogous back reaction of CO with CpFe(μ-CO)3FeCp. Moreover, unlike many CO-loss intermediates, there is no reaction of 4 with PPh3. The rate of reaction of 4 with THF, to produce Cp*2Cr2(CO)3(THF) (6), has been estimated (k2 = 1.6 (±0.2) x 108 M-1 s-1).

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DO - 10.1021/om970641b

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JF - Organometallics

IS - 26

ER -

Unusual structure and reactivity of the photogenerated intermediate CpCr(μ-CO)₃CrCp (Cp* = η⁵-C₅Me₅)

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