η3-Allyl complexes of molybdenum—IV. Preparation and crystal structures of some substituted-cyclopentadienyl molybdenum allyl derivatives

Andell, Ove S.; Goddard, Richard; Holle, Sigrid; Jolly, P. W.; Tsay, Yi‐Hung

doi:10.1016/s0277-5387(00)86504-3

Cited by 20 publications

(10 citation statements)

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“…The only previously known organometallic Mo(III) compounds containing only Mo-C bonds are CpMo( 3 -allyl) 2 and analogues with substituted Cp rings, 34,35 and the one-electron oxidization product of system V. 44 The potentials for the oxidation of 4 to 5 are in the range observed for Cp*MoCl(CO)L 2 derivatives (e.g. E 1/2 = -0.48 V for L = PMe 3 and -0.44 V for L 2 = dppe), 52 whereas compound 1 is more stable in the Mo(III) neutral form relative to the reduced Mo(II) anion (E 1/2 = -1.03 V).…”

Section: Methodsmentioning

confidence: 99%

“…Precedents for structures containing allyl or diene ligands for half sandwich Mo(III) are CpMoCl 2 (supine- 4 -C 4 H 6 ) 14 and a variety of (Ring)Mo(supine- 3 -C 3 H 5 ) 2 (Ring = Cp, 2-methylindenyl, 2-metoxyindenyl, and 5,6-dimetoxyindenyl). 34,35 Figure 7. Molecular geometry of the cation 5b with the numbering scheme employed.…”

Section: (B) Electrochemistry Studies and Syntheses And Epr Characterization Of Mo(iii)mentioning

confidence: 99%

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Cyclopentadienylmolybdenum(II) and -(III) Complexes Containing Diene and Allyl Ligands. 1. Isomeric Preferences and Isomerization Rates in a Pair of Redox-Related Organometallic Complexes

1997

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Treatment of CpMoCl 2 (-C 4 H 6 ) (1) with 1 equiv of allylmagnesium bromide yields the dinuclear complexes [CpMo(-C 4 H 6 )(µ-Br)] 2 (2, major) and Cp 2 Mo 2 (-C 4 H 6 ) 2 (µ-Br)(µ-Cl) (3, minor). A solid solution of compounds 2 and 3 adopts an anti geometry in the solid state, as shown by X-ray crystallography, whereas both anti and syn isomers are observed in benzene solution by 1 H NMR spectroscopy. The reaction of 1 with 2 equiv of allylmagnesium bromide yields [CpMo(-C 3 H 5 )(-C 4 H 6 )] as an equilibrium mixture of a major (98%, 4a) and a minor (2%, 4b) isomer. NOE-NMR studies indicate the CpMo(prone-C 3 H 5 )(supine-C 4 H 6 ) orientation for the major isomer 4a, which is also found in the solid state by X-ray crystallography. The orientation of 4b is suggested by the 1 H-NMR chemical shifts as CpMo(supine-C 3 H 5 )(supine-C 4 H 6 ). Oxidation of 4a/b by ferrocenium hexafluorophosphate in dichloromethane gives the 17-electron compounds [CpMo(-C 3 H 5 )(-C 4 H 6 )][PF 6 ] (5a/b).The green compound 5a converts into the more stable red-violet 5b with an estimated half-life of < 20 s in THF. It can be observed, however, at low temperature by EPR spectroscopy. The [CpMo(supine--C 3 H 5 )(supine--C 4 H 6 )][PF 6 ] configuration for 5b has been confirmed by Xray diffraction methods. Upon reduction with cobaltocene, 5b is converted selectively to 4b, followed by slow equilibration (t 1/2 = 6.5 h) with 4a. Refluxing or photolyzing a solution of 4a/b in benzene generates a third isomer, 4c, which adopts a CpMo(supine-C 3 H 5 )(s-trans-C 4 H 6 ) configuration as confirmed by an X-ray analysis. The distribution of 4a and 4c at equilibrium is approximately 1:1 either by starting from 4a/b or from pure 4c and independent of equilibration method (thermal/photochemical).Oxidation of 4c generates the corresponding 1-electron oxidation product 5c, which rapidly isomerizes to 5b. It can be observed, however, by EPR in THF together with a fourth isomer 5d (ca. 1:1), believed to differ from 5c only in the orientation of the allyl ligand. Equilibrium, rate, and electrochemical data allow to sort out most of the thermodynamic and kinetic parameters related to the transformation of the different compounds. The faster s-trans-to s-cis-butadiene isomerization for 5 relative to 4 indicates the easier accessibility of the unsaturated 15-electron vs. 16-electron intermediate. Possible reasons for this trend are analyzed.

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Section: Methodsmentioning

confidence: 99%

Section: (B) Electrochemistry Studies and Syntheses And Epr Characterization Of Mo(iii)mentioning

confidence: 99%

Cyclopentadienylmolybdenum(II) and -(III) Complexes Containing Diene and Allyl Ligands. 1. Isomeric Preferences and Isomerization Rates in a Pair of Redox-Related Organometallic Complexes

1997

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“…and have shown compati-bility with a large array of ligands. Examples with X = halide, 1-5 hydrosulfido, alkane-and aryenethiolato, 6-9 amido, 10 dialkylphosphido, 11 phenyldiazo, 12 isocyanato, 13 azido, 14 alkyl, 15 and hydroborate units, 16 L=phosphine, 17-21 CO 22-26 isocyanides 27, 28 and MeCN, 27,29,30 L2 =diphosphines, [31][32][33] phosphine sulfides 34 and dienes, [35][36][37][38] and XL=phosphine-thiolato 34 and allyl [37][38][39][40] have been reported. Our own work in this area has been summarized in review articles.…”

mentioning

confidence: 99%

Half-sandwich complexes of molybdenum-(III), -(IV) and -(V) with P–O and P–N bifunctional ligands Ph2PCH2X (X = 2-oxazolinyl, or C(O)NPh2)

Camus

Morales

Andrieu

et al. 2000

J. Chem. Soc., Dalton Trans.

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“…[31], while the corresponding Mo complex 2 does not undergo a similar process under mild conditions [6,32,33], in accord with the expected greater stability of the heavier metal in the higher oxidation state. We have now found that 2 yields a mixture of propene and 1,5-hexadiene in a ca.…”

Section: Allyl-allyl Couplingmentioning

confidence: 83%

Comparative chemistry of 18-electron Mo(II) and 17-electron Mo(III) compounds containing only carbon-based ligands

Poli

Wang²

1998

Coordination Chemistry Reviews

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η3-Allyl complexes of molybdenum—IV. Preparation and crystal structures of some substituted-cyclopentadienyl molybdenum allyl derivatives

Cited by 20 publications

References 10 publications

Cyclopentadienylmolybdenum(II) and -(III) Complexes Containing Diene and Allyl Ligands. 1. Isomeric Preferences and Isomerization Rates in a Pair of Redox-Related Organometallic Complexes

Cyclopentadienylmolybdenum(II) and -(III) Complexes Containing Diene and Allyl Ligands. 1. Isomeric Preferences and Isomerization Rates in a Pair of Redox-Related Organometallic Complexes

Half-sandwich complexes of molybdenum-(III), -(IV) and -(V) with P–O and P–N bifunctional ligands Ph2PCH2X (X = 2-oxazolinyl, or C(O)NPh2)

Comparative chemistry of 18-electron Mo(II) and 17-electron Mo(III) compounds containing only carbon-based ligands

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