Interactions of CpM'(CO)3- (M' = chromium, molybdenum, or tungsten) with cations: effects on CO exchange and RX addition reactions

Darensbourg, Marcetta Y.; Jimenez, Pedro; Sackett, James R.; Hanckel, John M.; Kump, Robin L.

doi:10.1021/ja00370a012

Cited by 71 publications

(33 citation statements)

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“…22 The weak component at ∼1980 cm -1 can be assigned to a fraction of [Cp 2 Cr(CO)] + species. 23,24 The k 3 -weighted FT of the EXAFS data and the corresponding XANES spectra (Figure 4a-d) reflect the behavior observed by IR and highlight the structural variations undergone by the Cp 2 Cr molecule upon CO addition in the two matrices. In particular, for the Cp 2 Cr/PS system, the |FT| (Figure 4a) exhibits an increase of the intensity of the first shell and a shift toward higher R values.…”

Section: Vibrational and Structural Properties Of The Reaction Producmentioning

confidence: 65%

Formation and reactivity of Cr^IIcarbonyls hosted in polar and non polar supports

Gianolio

Groppo

Estephane

et al. 2009

J. Phys.: Conf. Ser.

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Organometallic complexes hosted inside porous frameworks are particularly interesting because of possible application in heterogeneous catalysis or electronic devices and optical materials. We present here a detailed spectroscopic investigation on the structure and reactivity towards simple reagents (such as CO) of chromocene molecules (Cp 2 Cr) encapsulated into the nanovoids of two different matrices: a non polar polystyrene (PS) and a polar NaY zeolite. We demonstrate that stable Cp 2 Cr(CO) complexes are formed in PS, while in NaY the presence of high internal electric fields confers to the Cp 2 Cr molecules a much higher reactivity towards CO. In situ EXAFS data, combined with other spectroscopic techniques and ab initio theoretical calculations, allowed the structural determination of the reaction products and afforded the full comprehension of the complex reactivity of Cp 2 Cr molecules inside the cavities of PS and NaY hosts.

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Section: Vibrational and Structural Properties Of The Reaction Producmentioning

confidence: 65%

Formation and reactivity of Cr^IIcarbonyls hosted in polar and non polar supports

Gianolio

Groppo

Estephane

et al. 2009

J. Phys.: Conf. Ser.

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“…35b). [868][869][870] On this basis, reaction (39) was inferred and supported by parallel Cr K-edge EXAFS analysis. 866,867 This reaction requires the presence of two Cp 2 Cr molecules inside the same supercage, as shown in the top-left inset in Fig.…”

Section: 1mentioning

confidence: 74%

Probing zeolites by vibrational spectroscopies

et al. 2015

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This review addresses the most relevant aspects of vibrational spectroscopies (IR, Raman and INS) applied to zeolites and zeotype materials. Surface Brønsted and Lewis acidity and surface basicity are treated in detail. The role of probe molecules and the relevance of tuning both the proton affinity and the steric hindrance of the probe to fully understand and map the complex site population present inside microporous materials are critically discussed. A detailed description of the methods needed to precisely determine the IR absorption coefficients is given, making IR a quantitative technique. The thermodynamic parameters of the adsorption process that can be extracted from a variable-temperature IR study are described. Finally, cutting-edge space- and time-resolved experiments are reviewed. All aspects are discussed by reporting relevant examples. When available, the theoretical literature related to the reviewed experimental results is reported to support the interpretation of the vibrational spectra on an atomic level.

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“…In particular, the hydrogen atoms 1 and 6–11 in the anions resonate at higher field than in their methylated relatives by an average of 0.15 ppm, and the corresponding dinuclear metal carbonyl stretching frequencies are attenuated by an average of ≈6 cm −1 . At the same time, charge depletion of the anionic center is indicated by more energetic CO bands (≈11 cm −1 ) than those measured for free [CpM(CO) 3 ] − 7b…”

Section: Methodsmentioning

confidence: 72%

Electron Exchange Along the Tercyclopentadienyltrimetallic Scaffold: Kinetics, Equilibria, and Bond Strengths

Cammack¹,

Amouri²,

Leonard³

et al. 2004

Angewandte Chemie

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___Electron transfer is fundamental to chemical reactivity.[1] A prototype example in organometallic chemistry is the attack of an anionic metal center on a metal-metal bond,Such is not cleanly found, however, the outcome of this mechanistically complex transformation usually being controlled by thermodynamic factors through electron redistribution to eventually provide M-M + M' -.[2] We report the first direct observation of such equilibria for cyclopentadienyl (Cp) metals by NMR, mechanistic studies, and the utilization of the data in the estimation of CpM-M'Cp bond strengths. Key to these results is the employment of the tercyclopentadienyl ligand as a frame on which to render the desired transformations intramolecular and regiospecific (Scheme 1). [3] ___The required materials were made according to described protocols (Table 1), [3,4] with a minor modification for the preparation of the anions 1-4, 7, 8, and 9, which, to avoid (competing) reduction of the metal-metal bond, were generated using NaH or (for 9) tert-BuOK. Structural proof of all new compounds rested on spectral data, conversion to stable methyl derivatives (in the case of the anions), and X-ray analyses of 3 and 4.Particularly diagnostic were the 1 H NMR spectra, which could be assigned, as appropriate, by comparison with known systems or known substructures, [3] by exploiting the effect of the anisotropy of a metal-metal bond on the δ values of the 1

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Interactions of CpM'(CO)3- (M' = chromium, molybdenum, or tungsten) with cations: effects on CO exchange and RX addition reactions

Cited by 71 publications

References 0 publications

Formation and reactivity of Cr^IIcarbonyls hosted in polar and non polar supports

Formation and reactivity of Cr^IIcarbonyls hosted in polar and non polar supports

Probing zeolites by vibrational spectroscopies

Electron Exchange Along the Tercyclopentadienyltrimetallic Scaffold: Kinetics, Equilibria, and Bond Strengths

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Interactions of CpM'(CO)3- (M' = chromium, molybdenum, or tungsten) with cations: effects on CO exchange and RX addition reactions

Cited by 71 publications

References 0 publications

Formation and reactivity of CrIIcarbonyls hosted in polar and non polar supports

Formation and reactivity of CrIIcarbonyls hosted in polar and non polar supports

Probing zeolites by vibrational spectroscopies

Electron Exchange Along the Tercyclopentadienyltrimetallic Scaffold: Kinetics, Equilibria, and Bond Strengths

Contact Info

Product

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About

Formation and reactivity of Cr^IIcarbonyls hosted in polar and non polar supports

Formation and reactivity of Cr^IIcarbonyls hosted in polar and non polar supports