Die Kristallstruktur und das Schwingungsspektrum von Tetramethylammonium‐tricarbonyl‐(π‐cyclopentadienyl)‐chromat(1‐), NMe4 [C5H5Cr(CO)3]

Feild, R.; Hellner, E.; Klopsch, A.; Dehnicke, Kurt

doi:10.1002/zaac.19784420122

Cited by 17 publications

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References 14 publications

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“…The average Cr−C(Cp) ring distance in the latter is 2.214 Å, slightly greater than that in the Cr−Cr bonded neutral system (2.189 Å). The trends observed compare well to those in the analogous FvW 2 pair 1a and are also evident in the couples Cp 2 Mo 2 (CO) 6 28a/CpMo(CO) 3 - 28b and Cp 2 Cr 2 (CO) 6 /CpCr(CO) 3 - . Finally, and as in the W relatives,1a the Cp−Cp bridge of the Fv moiety lengthens somewhat on going from the neutral (1.433 Å) to the charged complex (1.480 Å), a phenomenon attributable to a number of factors, including removal of the bridging Cr−Cr bond and charge repulsion.…”

Section: Resultssupporting

confidence: 72%

Thermodynamic and Kinetic Study of Oxidative Addition/Reductive Elimination of H₂ and D₂ to FulvaleneCr₂(CO)₆: Evidence for Relatively Strong Metal−Metal Bonds in Fulvalenedimetals

et al. 1999

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Hydrogen adds reversibly to the chromium-chromium bond of FvCr 2 (CO) 6 yielding FvCr 2 (CO) 6 (H) 2 (Fv ) fulvalene). Equilibrium data for this process have been measured in toluene and deuteriobenzene in the temperature range 50-80 °C and pressures up to 72 atm H 2 [∆H°) -1.0(0.4) kcal/mol, ∆S°) -14.0(2.0) cal/mol deg]. These data are used to estimate the enthalpy [16.5 (2.0) kcal/mol] and entropy (11 cal/mol deg) for breaking the Cr-Cr bond in FvCr 2 (CO) 6 . A theoretical calculation of the isodesmic process FvCr 2 (CO) 6 (H) 2 + [η 5 -C 5 H 5 Cr-(CO) 3 ] 2 f FvCr 2 (CO) 6 + 2 η 5 -C 5 H 5 Cr(CO) 3 H predicts it to have an enthalpy of -1.74 kcal/mol, very close to the experimental value of -2 kcal/mol. Thus, and assuming that the individual Cr-H bonds in FvCr 2 (CO) 6 (H) 2 and η 5 -C 5 H 5 Cr(CO) 3 H are equal, these results lead to the conclusion that the metal-metal bond in the fulvalene system is 2 ( 2 kcal/mol stronger than that in [η 5 -C 5 H 5 Cr(CO) 3 ] 2 , despite the greater Cr-Cr bond length in the former. This result is also in accord with the measured enthalpy of reaction [FvCr 2 (CO) 6 ] 2-(Na + ) 2 + [η 5 -C 5 H 5 -Cr(CO) 3 ] 2 f FvCr 2 (CO) 6 + 2 [η 5 -C 5 H 5 Cr(CO) 3 ] -Na + , ∆H ) -2.4(0.4) kcal/mol. Deuterium was found to add to FvCr 2 (CO) 6 with a normal equilibrium isotope effect: K eq (H 2 )/K eq (D 2 ) ) 1.45(0.10). A kinetic study of reductive elimination of H 2 in the temperature range 45-75 °C shows that it obeys first-order kinetics: [k -1 45.5 ) 1.0 × 10 -5 s -1 , ∆H q ) 27.8(2.0) kcal/mol, ∆S q ) 5.6(3.0) cal/mol deg]. Similarly, the oxidative addition reaction reveals first-order behavior in both FvCr 2 (CO) 6 and H 2 [∆H q ) 26.8(2.5) kcal/mol, ∆S q ) -19.6 (6.0) cal/mol deg]. The obtained combined kinetic data are in reasonable agreement with the measured equilibrium constant. The rate of hydrogenation under 60 atm of H 2 is not retarded by addition of 15 atm of CO, arguing against a transition state involving CO loss. Studies of the rate of oxidative addition/reductive elimination of D 2 suggest a late transition state for the former which involves cleavage of the D-D (H-H) bond. Substitution of 12 CO in FvCr 2 ( 12 CO) 6 by 13 CO occurs 1-2 orders of magnitude faster than does hydrogenation [k 1 43.7 ) 5.6 × 10 -6 s -1 atm -1 , ∆H q ) 16.7(1.5) kcal/mol, ∆S q ) -30.0(4.0) cal/mol deg] but is much slower than in analogous complexes [η 5 -C 5 R 5 Cr(CO) 3 ] 2 (R ) H, Me). The crystal structure of [FvCr 2 (CO) 6 ] 2-(Na + ) 2 is reported.

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Section: Resultssupporting

confidence: 72%

Thermodynamic and Kinetic Study of Oxidative Addition/Reductive Elimination of H₂ and D₂ to FulvaleneCr₂(CO)₆: Evidence for Relatively Strong Metal−Metal Bonds in Fulvalenedimetals

et al. 1999

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Ion Pairing Effects on Transition Metal Carbonyl Anions

Darensbourg

1985

Progress in Inorganic Chemistry

136

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Applications in Organometallic Chemistry

2008

Infrared and Raman Spectra of Inorganic and Coordination Compounds

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Die Kristallstruktur und das Schwingungsspektrum von Tetramethylammonium‐tricarbonyl‐(π‐cyclopentadienyl)‐chromat(1‐), NMe₄ [C₅H₅Cr(CO)₃]

Cited by 17 publications

References 14 publications

Thermodynamic and Kinetic Study of Oxidative Addition/Reductive Elimination of H₂ and D₂ to FulvaleneCr₂(CO)₆: Evidence for Relatively Strong Metal−Metal Bonds in Fulvalenedimetals

Thermodynamic and Kinetic Study of Oxidative Addition/Reductive Elimination of H₂ and D₂ to FulvaleneCr₂(CO)₆: Evidence for Relatively Strong Metal−Metal Bonds in Fulvalenedimetals

Ion Pairing Effects on Transition Metal Carbonyl Anions

Applications in Organometallic Chemistry

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Die Kristallstruktur und das Schwingungsspektrum von Tetramethylammonium‐tricarbonyl‐(π‐cyclopentadienyl)‐chromat(1‐), NMe4 [C5H5Cr(CO)3]

Cited by 17 publications

References 14 publications

Thermodynamic and Kinetic Study of Oxidative Addition/Reductive Elimination of H2 and D2 to FulvaleneCr2(CO)6: Evidence for Relatively Strong Metal−Metal Bonds in Fulvalenedimetals

Thermodynamic and Kinetic Study of Oxidative Addition/Reductive Elimination of H2 and D2 to FulvaleneCr2(CO)6: Evidence for Relatively Strong Metal−Metal Bonds in Fulvalenedimetals

Ion Pairing Effects on Transition Metal Carbonyl Anions

Applications in Organometallic Chemistry

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Die Kristallstruktur und das Schwingungsspektrum von Tetramethylammonium‐tricarbonyl‐(π‐cyclopentadienyl)‐chromat(1‐), NMe₄ [C₅H₅Cr(CO)₃]

Thermodynamic and Kinetic Study of Oxidative Addition/Reductive Elimination of H₂ and D₂ to FulvaleneCr₂(CO)₆: Evidence for Relatively Strong Metal−Metal Bonds in Fulvalenedimetals

Thermodynamic and Kinetic Study of Oxidative Addition/Reductive Elimination of H₂ and D₂ to FulvaleneCr₂(CO)₆: Evidence for Relatively Strong Metal−Metal Bonds in Fulvalenedimetals