Photoelectron studies of some bent bis(η-cyclopentadienyl)metal complexes. Part I. Some eighteen-electron systems with hydride, alkyl, olefin, allyl, and carbonyl ligands

Green, Jennifer C.; Jackson, Sally E.; Higginson, Brian R.

doi:10.1039/dt9750000403

Cited by 55 publications

(21 citation statements)

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“…That of [W(η-C 5 H 5 ) 2 H 2 ] has been published previously. 12 Band A is assigned to ionisation of the two d electrons. Band B comprises ionisations from both the highest occupied orbitals of the cyclopentadienyl rings and the tungsten-hydrogen bonding electrons.…”

Section: Resultsmentioning

confidence: 99%

Studies of ansa-bis(cyclopentadienyl)tungsten derivatives

Conway¹,

Dijkstra²,

Doerrer³

et al. 1998

J. Chem. Soc., Dalton Trans.

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The new compounds [W{(η-C 5 H 4 )X(η-C 5 H 4 )}Cl 2 ] 1, [W{(η-C 5 H 4 )X(η-C 5 H 4 )}Me 2 ] 2, [W{(η-C , where X = SiMe 2 , SiEt 2 or CMe 2 CMe 2 , and Y = BF 4 or Cl, have been prepared. The crystal structures of [W{(η-C 5 H 4 )X(η-C 5 H 4 )}Me 2 ] (X = SiMe 2 or CMe 2 CMe 2 ) have been determined.Recently we have described ansa-metallocenes of tungsten and molybdenum and shown that their properties are significantly different from non-ansa analogues. 1,2 In particular we noted that the complex [W{(η-C 5 H 4 )CMe 2 (η-C 5 H 4 )}H 3 ] ϩ PF 6 Ϫ displays exceptional highly temperature variable 1 H NMR spectroscopic data with 2 J(HH) of ca. 16 000 Hz at Ϫ70 ЊC attributed to quantum mechanical exchange coupling. By comparison, [W(η-C 5 H 5 ) 2 H 3 ] ϩ BF 4 Ϫ shows very different temperature independent behaviour. 3 We have prepared a number of related ansa-tungstenocene complexes to investigate the effect that changes in the bridging ring substituents have upon their properties.Compound and analysis a 1a [W{(η-C 5 H 4 )SiMe 2 (η-C 5 H 4 )}Cl 2 ] Green C, 28.7 (28.7); H, 3.7 (3.3) Spectroscopic data b 1 H: c 6.12 (4 H, m, C 5 H 4 ), 5.81 (4 H, m, C 5 H 4 ), 0.09 (6 H, s, Me 2 Si) 13 C-{ 1 H}: c 125.9 (s, C 5 H 4 ), 78.7 (s, C 5 H 4 ), 66.0 (s, C 5 H 4 , C ipso ), Ϫ5.9 (s, SiMe 2 ) Mass (FAB): m/z 442 (M ϩ ), 405 (M ϩ Ϫ Cl) 1b [W{(η-C 5 H 4 )SiEt 2 (η-C 5 H 4 )}Cl 2 ] Green 1

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Section: Resultsmentioning

confidence: 99%

Studies of ansa-bis(cyclopentadienyl)tungsten derivatives

Conway¹,

Dijkstra²,

Doerrer³

et al. 1998

J. Chem. Soc., Dalton Trans.

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“…The broadness of these low energy ionization bands indicates large reorganization energies upon formation of the cation structures 25. For comparison with the ionizations of metal d electrons that are largely localized on the metal center and in non-bonding interactions, the width at half-height of the predominantly metal d a 1 ionization of (η 5 -C 5 H 5 ) 2 Mo(CH 3 ) 2 is about 0.3 eV26 and that of the predominantly metal d a 1g ionization of ferrocene is about 0.1 eV 27. The width at half-height for the first ionizations shown in Figure 3 are on the order of 0.6 eV.…”

Section: Resultsmentioning

confidence: 99%

New Insights into Solvolysis and Reorganization Energy from Gas-Phase, Electrochemical, and Theoretical Studies of Oxo-Tp*Mo^V Molecules

et al. 2009

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Molecules of the general form Tp*MoO(OR)2 (where Tp* = hydrotris(3,5-dimethyl-1-pyrazolyl)borate and (OR)2 = (OMe)2, (OEt)2, and (OnPr)2 for alkoxide ligands, and (OR)2 = O(CH2)3O, O(CH2)4O, and O[CH(CH3)CH2CH(CH3)]O for diolato ligands) were studied using gas-phase photoelectron spectroscopy, cyclic voltammetry, and density functional theory calculations to examine the effect of increasing ligand size and structure on the oxo-molybdenum core. Oxidation potentials and first ionization energies are shown to be sensitive to the character of the diolato and alkoxide ligands. A linear correlation between the solution-phase oxidation potentials and the gas-phase ionization energies resulted in an unexpected slope of greater than unity. Density functional theory calculations indicated that this unique example of a system in which oxidation potentials are more sensitive to substitution than vertical ionization energies is due to the large differences in the cation reorganization energies, which range from 0.2 eV or less for the molecules with diolato ligands to around 0.5 eV for the molecules with alkoxide ligands.

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“…This scheme has been used in the interpretation of PE spectra [3,4]. Only some points of special relevance for our work will be discussed here.…”

Section: Bonding Schemementioning

confidence: 99%

“…Crystallography, EPR and UPS studies [3,6,9] on d°, d 1 and d 2 complexes prove that the HOMO is a metal d orbital of ai symmetry (in C2v). Upon occupation of this orbital (going from d° to d 1 to d 2 ) the LML bond angle decreases owing to electrostatic repulsion.…”

Section: Introductionmentioning

confidence: 99%

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UV Photoelectron Spectra of Some Bent Bis(η⁵ -cyclopentadienyl) Niobium and Tantalum Complexes

Dam

Terpstra

Oskam

et al. 1981

Zeitschrift Für Naturforschung B

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Abstract He(I) and He(II) photoelectron spectra are reported for (η5-C5H5)2MLX (M = Nb, Ta; L = H, CO; X - propene, 1-butene, propyl) and some methylcyclopentadienyl deriva-tives. Also the spectra of some π-allyl and dihalide complexes are reported. Unambiguous assignments could be made of the metal d a1 orbital, the Cp orbitals, the olefin π ionization and the M-hydride and π-allyl orbitals. Very regular trends are observed in the ionization energies upon substitution of the ligands. The olefin π ionization is found at very low energy indicating that the π backbonding to the olefin is very important. He(I)/He(II) cross section differences show clearly differences in metal character of the various M.O.'s.

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Photoelectron studies of some bent bis(η-cyclopentadienyl)metal complexes. Part I. Some eighteen-electron systems with hydride, alkyl, olefin, allyl, and carbonyl ligands

Cited by 55 publications

References 0 publications

Studies of ansa-bis(cyclopentadienyl)tungsten derivatives

Studies of ansa-bis(cyclopentadienyl)tungsten derivatives

New Insights into Solvolysis and Reorganization Energy from Gas-Phase, Electrochemical, and Theoretical Studies of Oxo-Tp*Mo^V Molecules

UV Photoelectron Spectra of Some Bent Bis(η⁵ -cyclopentadienyl) Niobium and Tantalum Complexes

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Photoelectron studies of some bent bis(η-cyclopentadienyl)metal complexes. Part I. Some eighteen-electron systems with hydride, alkyl, olefin, allyl, and carbonyl ligands

Cited by 55 publications

References 0 publications

Studies of ansa-bis(cyclopentadienyl)tungsten derivatives

Studies of ansa-bis(cyclopentadienyl)tungsten derivatives

New Insights into Solvolysis and Reorganization Energy from Gas-Phase, Electrochemical, and Theoretical Studies of Oxo-Tp*MoV Molecules

UV Photoelectron Spectra of Some Bent Bis(η5 -cyclopentadienyl) Niobium and Tantalum Complexes

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Product

Resources

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New Insights into Solvolysis and Reorganization Energy from Gas-Phase, Electrochemical, and Theoretical Studies of Oxo-Tp*Mo^V Molecules

UV Photoelectron Spectra of Some Bent Bis(η⁵ -cyclopentadienyl) Niobium and Tantalum Complexes