μ-Dichloro-bis-[(π-benzene-π-allyl)molybdenum(II)]

Prout, Keith; Rees, G. V.

doi:10.1107/s0567740874006868

Cited by 6 publications

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“…The 1:1 ratio of syn and anti isomers in solution for both dinuclear compounds 2 and 3 indicates little or no steric interaction between the ligands bonded to the two different metals. The previously reported isoelectronic complexes [(η 6 -C 6 H 6 )Mo(η 3 -allyl)(μ-Cl)] 2 could not be investigated by NMR because of low solubility; thus, their relative syn/anti proportion is not known, although an X-ray structure of anti -[(η 6 -C 6 H 6 )Mo(η 3 -C 3 H 5 )(μ-Cl)] 2 has been determined . For the related compound [(η 6 -2,6-lutidine)Mo(η 3 -C 3 H 5 )(μ-Cl)] 2 on the other hand, only one isomer has been reported in solution and the X-ray analysis shows the anti arrangement in the solid state …”

Section: Discussionmentioning

confidence: 99%

“…The previously reported isoelectronic complexes [(η 6 -C 6 H 6 )Mo(η 3 -allyl)(µ-Cl)] 2 could not be investigated by NMR because of low solubility; thus, their relative syn/anti proportion is not known, 41 although an X-ray structure of anti-[(η 6 -C 6 H 6 )-Mo(η 3 -C 3 H 5 )(µ-Cl)] 2 has been determined. 42 For the related compound [(η 6 -2,6-lutidine)Mo(η 3 -C 3 H 5 )(µ-Cl)] 2 on the other hand, only one isomer has been reported in solution and the X-ray analysis shows the anti arrangement in the solid state. 43 This phenomenon may be attributed to the large steric bulk of the 2,6-lutidine ligand.…”

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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: Discussionmentioning

confidence: 99%

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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The Coordination and Bioinorganic Chemistry of Molybdenum

Stiefel¹

1977

Progress in Inorganic Chemistry

386

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Röntgenstrukturanalyse der dreifach methoxoverbrückten Komplexe η³‐Cycloheptatrienyldicarbonylmolybdäntris‐(μ‐methoxo)‐ η⁷‐cycloheptatrienylmolybdän, η³‐C₇H₇(CO)₂ Mo(μ‐OCH₃)₃Mo‐η⁷‐C₇H₇ und η³‐Cycloheptatrienyldicarbonylwolframtris‐ (μ‐methoxo)‐η⁴‐cycloheptatriendicarbonylwolfram, η³‐C₇H₇(CO)₂W (μ‐OCH₃)₃
Weidenhammer
¹
,
Ziegler
²

1979
Zeitschrift anorg allge chemie
7
0
0
0
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Die Kristall‐ und Molekülstrukturen der analog hergestellten Komplexe η3‐C7H7(CO)2Mo (μ‐OCH3)3Mo‐η7‐C7H7 und η3‐C7H7 (CO)2W(μ‐OCH3)3W‐ η4C7H8(CO)2 wurden mit tels Röntgenstrukturanlyse ermittelt. Die Anordnung der Brücken im triklinen Molybdänkomplex weist angenähert C3v‐Symmetrie auf, im monoklinen Wolframkomplex C8‐Symmetrie. In der paramagnetischen mixed‐valence Molybdänspezies sind die C7H7‐Ringe η3‐ bzw. η7‐gebunden, im diamagnetischen Wolframkomplex liegt ein η3‐koordinierter C7H7‐ bzw. ein η4‐gebundener C7H8‐Ligand vor.

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μ-Dichloro-bis-[(π-benzene-π-allyl)molybdenum(II)]

Abstract: Patterson methods were used to determine the structure from linear diffractometer intensity measurements. The final R was 0.049. The deviations from the expected values in bond lengths and angles were not significant. The molecules do not have an intramolecular metal-metal bond.

Cited by 6 publications

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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

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

The Coordination and Bioinorganic Chemistry of Molybdenum

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