The vibrational spectra of cyclopentadienyltungsten tricarbonyl complexes

Davidson, G.; Duce, David A.

doi:10.1016/s0022-328x(00)98029-x

Cited by 6 publications

(2 citation statements)

References 10 publications

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“…Bending modes of metal hydrides normally appear in the 700-950 cm -1 region, 30,31 but numerous absorptions appear in that region of the IR spectrum, so δ(M-H) bending modes are often difficult to assign. An IR and Raman spectroscopic study of Cp(CO) 3 WH did not locate the δ(W-H) bending modes, 32 but δ(M-H) bending modes were located and assigned in related metal carbonyl hydrides, 731 cm -1 for (CO) 5 MnH 33 and 708 cm -1 for (CO) 4 CoH. 34 A recent computational study supported these assignments and also calculated δ(M-H) bending modes for several related metal carbonyl hydrides.…”

Section: Resultsmentioning

confidence: 98%

Isotope Effects on Hydride Transfer Reactions from Transition Metal Hydrides to Trityl Cation. An Inverse Isotope Effect for a Hydride Transfer

Cheng

Bullock

1999

J. Am. Chem. Soc.

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Hydride transfer from transition metal hydrides (MH) to Ph3C+BF4 - gives M−FBF3 and Ph3CH. Deuterium kinetic isotope effects were determined for several MH/MD pairs (CH2Cl2 solution, 25 °C). For hydride transfer from Cp*(CO)3MoH (Cp* = η5-C5Me5) to substituted trityl cations containing zero, one, two, or three p-MeO groups [Ph n (p-MeOC6H4)3 - n C+BF4 -; n = 3, 2, 1, 0], the isotope effect remains essentially constant at k MoH/k MoD = 1.7−1.9 as the rate constant decreases from k H − = 6.5 × 103 to 1.4 M-1 s-1. For hydride transfer to Ph3C+BF4 - from five metal hydrides [Cp(CO)3MoH, Cp*(CO)3WH, (indenyl)(CO)3WH, Cp*(CO)3MoH, and trans-Cp(CO)2(PCy3)MoH; Cp = η5-C5H5] with second-order rate constants k H − ≥ 3.8 × 102 M-1 s-1, the kinetic isotope effects are also k MH/k MD = 1.7−1.8. For a series of five tungsten hydrides with substituted Cp ligands, the kinetic isotope effects decrease from k WH/k WD = 1.8 to 0.47 as the rate constant decreases (from k H − = 2.0 × 103 to 0.72 M-1 s-1). The steadily decreasing values of k MH/k MD with decreasing rate constants of hydride transfer are interpreted as indicating progressively stronger force constants of isotopically sensitive modes of the transition state, as the reaction slows down in progressing from more electron-donating Cp ligands to less electron-rich Cp ligands. The inverse isotope effect (k WH/k WD = 0.47) found for the slowest tungsten hydride, (C5H4CO2Me)(CO)3WH, is proposed to be due to a product-like transition state for irreversible hydride transfer.

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Section: Resultsmentioning

confidence: 98%

Isotope Effects on Hydride Transfer Reactions from Transition Metal Hydrides to Trityl Cation. An Inverse Isotope Effect for a Hydride Transfer

Cheng

Bullock

1999

J. Am. Chem. Soc.

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“…The lower frequency band is broader and has nonsymmetric shape due to overlap of the asymmetric stretching vibrations ν 2 CO (A′′) and ν 3 CO (A′). 47,48 The high frequency band ν 1 CO is assigned to symmetric stretching vibration of CO groups A′. The position of the low frequency ν CO band depends slightly on temperature, shifting to lower frequencies upon cooling (see the Supporting Information for details) with the concomitant increase in the intensity of both bands.…”

Section: Hydrogen Bonds Between Hydrides 1 and Bases (In Hexanementioning

confidence: 99%

Neutral Transition Metal Hydrides as Acids in Hydrogen Bonding and Proton Transfer: Media Polarity and Specific Solvation Effects

et al. 2010

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Structural, spectroscopic, and electronic features of weak hydrogen-bonded complexes of CpM(CO)(3)H (M = Mo (1a), W (1b)) hydrides with organic bases (phosphine oxides R(3)PO (R = n-C(8)H(17), NMe(2)), amines NMe(3), NEt(3), and pyridine) are determined experimentally (variable temperature IR) and computationally (DFT/M05). The intermediacy of these complexes in reversible proton transfer is shown, and the thermodynamic parameters (DeltaH degrees , DeltaS degrees ) of each reaction step are determined in hexane. Assignment of the product ion pair structure is made with the help of the frequency calculations. The solvent effects were studied experimentally using IR spectroscopy in CH(2)Cl(2), THF, and CH(3)CN and computationally using conductor-like polarizable continuum model (CPCM) calculations. This complementary approach reveals the particular importance of specific solvation for the hydrogen-bond formation step. The strength of the hydrogen bond between hydrides 1 and the model bases is similar to that of the M-H...X hydrogen bond between 1 and THF (X = O) or CH(3)CN (X = N) or between CH(2)Cl(2) and the same bases. The latter competitive weak interactions lower the activities of both the hydrides and the bases in the proton transfer reaction. In this way, these secondary effects shift the proton transfer equilibrium and lead to the counterintuitive hampering of proton transfer upon solvent change from hexane to moderately polar CH(2)Cl(2) or THF.

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2018

Vibrational Spectra of Organometallics

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The vibrational spectra of cyclopentadienyltungsten tricarbonyl complexes

Cited by 6 publications

References 10 publications

Isotope Effects on Hydride Transfer Reactions from Transition Metal Hydrides to Trityl Cation. An Inverse Isotope Effect for a Hydride Transfer

Isotope Effects on Hydride Transfer Reactions from Transition Metal Hydrides to Trityl Cation. An Inverse Isotope Effect for a Hydride Transfer

Neutral Transition Metal Hydrides as Acids in Hydrogen Bonding and Proton Transfer: Media Polarity and Specific Solvation Effects

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