Electronic structure of molybdenocene and tungstenocene: detection of paramagnetism by magnetic circular dichroism in argon matrixes

Cox, P. A.; Grebenik, Peter D.; Perutz, Robin N.; Robinson, Mark D.; Grinter, R.; Stern, David R.

doi:10.1021/ic00166a025

Cited by 35 publications

(26 citation statements)

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“…From the experimental point of view, chromocene is a stable triplet compound22 whereas molybdenocene and tungstenocene cannot be isolated. However, a magnetic circular dichroism study demonstrates their triplet ground state 23,24. The calculated Cr–Cp (center) distance of 1.833 Å for triplet Cp 2 Cr is in relatively good agreement with the experimentally determined one of 1.791(4) Å 25.…”

Section: Resultssupporting

confidence: 72%

Orbital Splitting and Pairing Energy in Open‐Shell Organometallics: A Study of Two Families of 16‐Electron Complexes [Cp₂M] (M = Cr, Mo, W) and [CpM(PH₃)] (M = Co, Rh, Ir)

Poli

Cacelli

2005

Eur J Inorg Chem

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The singlet-triplet gap for two families of 16-electron organometallic complexes has been examined in detail by DFT calculations at the B3LYP level with polarized basis sets on both metal and ligands. For the first family, the group 6 metallocenes (Cp 2 M with Cp = η 5 -C 5 H 5 and M = Cr, Mo, W), the singlet-triplet gap (E S -E T ) is always positive and decreases continuously on going from Cr to Mo to W. For the family of group 9 CpM(PH 3 ), on the other hand, there is a decrease on going from Co to Rh, followed by a slight increase on going further to Ir. These trends have been analyzed in qualitative monoelectronic terms as a function of the competition be-

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Section: Resultssupporting

confidence: 72%

Orbital Splitting and Pairing Energy in Open‐Shell Organometallics: A Study of Two Families of 16‐Electron Complexes [Cp₂M] (M = Cr, Mo, W) and [CpM(PH₃)] (M = Co, Rh, Ir)

Poli

Cacelli

2005

Eur J Inorg Chem

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“…The 16-electron bis(cyclopentadienyl) complexes were computed in two spin states, singlet and triplet. The triplet is more stable than the singlet for all systems investigated here, as experimentally established for Mo and W. 17 For the non ansa complexes, the triplet has a "linear" structure around the metal, with nearly parallel cyclopentadienyl rings. In contrast, the higher-lying singlet has a bent structure, with a Cnt-M-Cnt' angle in the 149-159Њ range, lower for the Mo species than the corresponding W species.…”

Section: [M] and 1 [M]supporting

confidence: 60%

Theoretical investigation of the spin crossover transition states of the addition of methane to a series of Group 6 metallocenes using minimum energy crossing points

Green

Harvey

Poli

2002

J. Chem. Soc., Dalton Trans.

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Density functional calculations are reported on the addition of methane to group 6 metallocenes, M(-C5H5)2 (M), M(CH2(-C5H4)2) (a-M) and M(-C5Me5)2 (M*) where M = Mo and W. Full geometry optimisations were carried out on the singlet and triplet 16 electron complexes, 1 [M and 3 [M]], the  2 -methane complexes, 1 [M( 2 -CH4)], and the hydridomethyl adducts, 1 [M(CH3)(H)]. The triplet state for [M] was found to be more stable for all six metallocenes, the difference being least in the case of the ansa-bridged system. Formation of the hydridomethyl comples was exoenergetic for all tungsten systems and for a-Mo, the other two Mo systems being endoenergetic. Minumum energy crossing points between the triplet and singlet surfaces were calculated for Mo, W, a-W and W*. These MECP formed the barrier to formation of the methane complex. Transition states for insertion of M into the C-H bond and exchange between the coordinated H of the methane complex were also calculated for Mo, W, a-W and W*. For W and W* these were of similar height to the MECP. For a-W the insertion barrier was lower than the MECP while for Mo it was higher. Activation of methane was established as being most favourable for a-W. The calculated results are fully in accord with published experimental data on hydrogen exchange in and thermal stablity of 1 [M(CH3)(H)] where M = W, a-W and W*.

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“…90 cm-', when the matrix is warmed to 30 K and subsequently recooled (Figure 2b). One component comes close to wavelengths of site absorption, whereas the other site is quite new (6). The separation between successive members of each progression, Y(, is about 314 cm-I (Table I, supplementary material).…”

Section: Wcpz In Nitrogenmentioning

confidence: 96%

Laser-Induced Fluorescence of Molybdenocene and Tungstenocene in Low-Temperature Matrixes

Hill¹,

Perutz²,

Rooney³

1995

J. Phys. Chem.

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The reactive metallocenes, tungstenocene and molybdenocene (M($-CsH5)2; M = Mo, W), have been generated by photolysis of the corresponding dihydnde complexes, M($-C~H~)ZHZ, in argon and nitrogen matrices at 12 K. The metallocenes have been probed by laser-induced fluorescence with a pulsed tunable laser and by UV/vis absorption spectroscopy. Structured emission is observed from the LMCT excited states (lifetimes 10 ns). The spectra are complicated by multiple sites/conformers, but emission spectra of a single site/ conformer may be obtained with appropriate selection of matrix and excitation wavelength. Corresponding excitation spectra are measured from the area of selected emission peaks as a function of excitation wavelength.Vibrational progressions are dominated by the ring-metal-ring symmetric stretching mode (v4 x 300 cm-l).Nevertheless, this mode changes in frequency by 1 4 cm-' (51.3%) in the LMCT excited state. The bestresolved peaks have a full width at half-maximum of ca. 10 cm-'. Most of the emission is vibrationally fully relaxed, but weak emission peaks arising from u' = 1 states are found for MoCpz in N2 matrices.

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Electronic structure of molybdenocene and tungstenocene: detection of paramagnetism by magnetic circular dichroism in argon matrixes

Cited by 35 publications

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Orbital Splitting and Pairing Energy in Open‐Shell Organometallics: A Study of Two Families of 16‐Electron Complexes [Cp₂M] (M = Cr, Mo, W) and [CpM(PH₃)] (M = Co, Rh, Ir)

Orbital Splitting and Pairing Energy in Open‐Shell Organometallics: A Study of Two Families of 16‐Electron Complexes [Cp₂M] (M = Cr, Mo, W) and [CpM(PH₃)] (M = Co, Rh, Ir)

Theoretical investigation of the spin crossover transition states of the addition of methane to a series of Group 6 metallocenes using minimum energy crossing points

Laser-Induced Fluorescence of Molybdenocene and Tungstenocene in Low-Temperature Matrixes

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Electronic structure of molybdenocene and tungstenocene: detection of paramagnetism by magnetic circular dichroism in argon matrixes

Cited by 35 publications

References 0 publications

Orbital Splitting and Pairing Energy in Open‐Shell Organometallics: A Study of Two Families of 16‐Electron Complexes [Cp2M] (M = Cr, Mo, W) and [CpM(PH3)] (M = Co, Rh, Ir)

Orbital Splitting and Pairing Energy in Open‐Shell Organometallics: A Study of Two Families of 16‐Electron Complexes [Cp2M] (M = Cr, Mo, W) and [CpM(PH3)] (M = Co, Rh, Ir)

Theoretical investigation of the spin crossover transition states of the addition of methane to a series of Group 6 metallocenes using minimum energy crossing points

Laser-Induced Fluorescence of Molybdenocene and Tungstenocene in Low-Temperature Matrixes

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Orbital Splitting and Pairing Energy in Open‐Shell Organometallics: A Study of Two Families of 16‐Electron Complexes [Cp₂M] (M = Cr, Mo, W) and [CpM(PH₃)] (M = Co, Rh, Ir)

Orbital Splitting and Pairing Energy in Open‐Shell Organometallics: A Study of Two Families of 16‐Electron Complexes [Cp₂M] (M = Cr, Mo, W) and [CpM(PH₃)] (M = Co, Rh, Ir)