Organometallic nitrosyl chemistry. 54. Reactions of 16-electron Cp'M(NO)R2 complexes of molybdenum and tungsten with water

Legzdins, Peter; Lundmark, Penelope J.; Phillips, Everett C.; Rettig, Steven J.; Veltheer, John E.

doi:10.1021/om00045a010

Cited by 19 publications

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“…Table 1 shows the calculated (NO) values for the more stable compounds, along with relevant experimental values. 6,9, [40][41][42] The Mo frequencies are calculated to be ~20 cm 1 higher than for W, accurately reflecting the experimentally-observed trend. 18 However, the calculated values are uniformly higher than the experimental frequencies, by up to 70 cm 1 or more for the methyl amido compounds.…”

Section: Cpm(no)(h2chch3)supporting

confidence: 71%

Theoretical Studies of the Reactivity of Cyclopentadienyl Nitrosyl Alkyl Species of Molybdenum and Tungsten

Poli

Smith

2000

Organometallics

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The reactivity differences observed experimentally for Cp*W(NO)(CH2CMe3)2 and CpMo(NO)(CH2CMe3)2 are investigated using density functional theory (DFT) techniques. The reactions of the CpW(NO)(CH2) model complex with NH3 and CH4 are more exothermic and have lower activation barriers than the corresponding processes for CpMo(NO)(CH2). The  2 -C,H methane complex CpM(NO)(CH2)(CH4) (M = Mo, W) can undergo two competitive processes: CH activation to afford CpM(NO)(CH3)2 or loss of methane. The relative barrier heights are almost identical for M = W, whereas the formation of CpM(NO)(CH3)2 is significantly disfavored for M = Mo. The activation of CH and NH bonds proceeds via a direct, metal-assisted 1,2 addition across the M=CH2 bond without a distinct carbene-hydride intermediate. The relative stability order of the products can be rationalized in part through metalligand -bonding considerations. The relative orbital energies, which are consistently lower for Mo than for W, can be used to rationalize various reactivity differences observed experimentally for the CpM(NO)(alkyl)2 species, including the selective coordination of small molecules. The absence of sufficient steric bulk in the model complexes likely contributes to the overestimation of the calculated activation energies, and the discrepancy between some of the calculated and experimental structural parameters.

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Section: Cpm(no)(h2chch3)supporting

confidence: 71%

Theoretical Studies of the Reactivity of Cyclopentadienyl Nitrosyl Alkyl Species of Molybdenum and Tungsten

Poli

Smith

2000

Organometallics

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“…Syntheses of 11 do not proceed cleanly, and the final product mixture typically contains some Cp*Mo(NO)(CH 2 SiMe 3 ) 2 even after having been chromatographed on silica. The presence of this byproduct is evident in the 1 H NMR spectrum of the product mixture, which displays a characteristic doublet at −1.17 ppm attributable to one of the diastereotopic protons of the C H 2 SiMe 3 ligand …”

Section: Resultsmentioning

confidence: 99%

Differing Reactions of Functionalized Hydrocarbons with Cp*M(NO)(alkyl)(η³-allyl) Complexes of Molybdenum and Tungsten

et al. 2011

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Cp*W(NO)(CH 2 CMe 3 )(η 3 -CH 2 CHCHMe) (1) is known to initiate facile and selective aliphatic C-H bond activations of hydrocarbons at ambient temperatures. Its ability to effect C-H activations of unfunctionalized hydrocarbon portions of more complex molecules containing various functional groups has now been investigated in some detail. In addition, molybdenum analogues of 1 have also been examined in order to see how the C-H activation chemistry is affected when the central metal is changed. Thermolyses of 1 in neat 1-chloropropane, 1-chlorobutane, and 1-bromobutane at room temperature result in activation of the terminal C-H bonds at the end opposite the carbon-halogen linkage and the clean formation of the alkyl-allyl complexes Cp*W(NO)(CH 2 CH 2 CH 2 Cl)(η 3 -CH 2 CHCHMe) (2), Cp*W(NO)(CH 2 (CH 2 ) 2 -CH 2 Cl)(η 3 -CH 2 CHCHMe) (3), and Cp*W(NO)(CH 2 (CH 2 ) 2 CH 2 Br)(η 3 -CH 2 CHCHMe) (4), respectively. No reaction occurs with the C-Cl or C-Br bonds in the haloalkanes even though they are weaker than the C-H bonds that are activated. Similarly, treatment of 1 with n-Bu 2 O yields exclusively the terminal 5), whereas the reaction with THF results in the single activation of a secondary sp 3 C-H bond R to the oxygen atom in THF and the formation of Cp*W(NO)(C 4 H 7 O)(η 3 -CH 2 CHCHMe) (6). Consistently, reaction of 1 with ethylcyclohexane results in preferential activation of one of the primary sp 3 C-H linkages of the ethyl group and the formation of Cp*W(NO)(CH 2 CH 2 C 6 H 11 )(η 3 -CH 2 CHCHMe) (7). The Cp*Mo(NO)(alkyl)(η 3allyl) complexes analogous to 1 are generally thermally unstable and react at or slightly above room temperature. The first member of this family of complexes to be studied was Cp*Mo(NO)(CH 2 CMe 3 )(η 3 -C 3 H 5 ) (8), whose thermolysis in the presence of pyridine at 35 °C over 3 days leads to the formation of Cp*Mo(NO)(C 5 H 5 N)(η 2 -CH 2 dCHCH 2 CH 2 -t-Bu) (9), an η 2 -olefin complex in which the allyl and neopentyl ligands have coupled. The related Cp*Mo(NO)(CH 2 SiMe 3 )(η 3 -CH 2 CHCHMe) complex (11) exists as a 2:1 mixture of isomers distinguishable by the orientation of the endo, syn allyl ligand. In the less sterically congested major isomer, the methyl group on the allyl ligand is adjacent to the NO ligand, but in the minor isomer the methyl group is adjacent to the more sterically demanding CH 2 SiMe 3 ligand. In general, the thermal reaction of 11 is similar to that of 1. Spectroscopic monitoring indicates that the loss of TMS from 11 at room temperature results in the formation of a 16e η 2 -diene intermediate complex that can be trapped with PMe 3 as an 18e adduct, Cp*Mo(NO)(η 2 -CH 2 dCHCHdCH 2 )(PMe 3 ) (12). However, reactions of 11 with various substrates (e.g., pentane, Et 2 O, and mesitylene) all lead to a single product, Cp*Mo(NO)(η 4 -trans-butadiene) (13). Evidently, the formation of the 18e butadiene complex is favored over the activation of a relatively electron-poor C-H bond by this molybdenum system. The results of DFT calculations on the model reaction ...

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“…Despite all this research, very few anionic alkylidene complexes have been isolated to date, even though deprotonation of an alkyl ligand in a neutral organometallic precursor would appear to be an attractive synthetic route to such species . We now report that an anionic alkylidene complex of molybdenum can be synthesized by exposing the 16e dialkyl complex Cp*Mo(NO)(CH 2 SiMe 3 ) 2 ( 1 ) to various lithium reagents and that the mechanistic pathway followed by these reactions is dependent on the lithium reagent employed. The chemistry that forms the basis of this report is summarized in Scheme in which R = SiMe 3 throughout.…”

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confidence: 96%

Novel Synthetic Routes to the Anionic Alkylidene Complex [Cp*Mo(NO)(CH₂SiMe₃)(CHSiMe₃)]^- from Its Neutral Dialkyl Precursor

Legzdins

Sayers

1996

Organometallics

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Organometallic nitrosyl chemistry. 54. Reactions of 16-electron Cp'M(NO)R2 complexes of molybdenum and tungsten with water

Cited by 19 publications

References 0 publications

Theoretical Studies of the Reactivity of Cyclopentadienyl Nitrosyl Alkyl Species of Molybdenum and Tungsten

Theoretical Studies of the Reactivity of Cyclopentadienyl Nitrosyl Alkyl Species of Molybdenum and Tungsten

Differing Reactions of Functionalized Hydrocarbons with Cp*M(NO)(alkyl)(η³-allyl) Complexes of Molybdenum and Tungsten

Novel Synthetic Routes to the Anionic Alkylidene Complex [Cp*Mo(NO)(CH₂SiMe₃)(CHSiMe₃)]^- from Its Neutral Dialkyl Precursor

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Organometallic nitrosyl chemistry. 54. Reactions of 16-electron Cp'M(NO)R2 complexes of molybdenum and tungsten with water

Cited by 19 publications

References 0 publications

Theoretical Studies of the Reactivity of Cyclopentadienyl Nitrosyl Alkyl Species of Molybdenum and Tungsten

Theoretical Studies of the Reactivity of Cyclopentadienyl Nitrosyl Alkyl Species of Molybdenum and Tungsten

Differing Reactions of Functionalized Hydrocarbons with Cp*M(NO)(alkyl)(η3-allyl) Complexes of Molybdenum and Tungsten

Novel Synthetic Routes to the Anionic Alkylidene Complex [Cp*Mo(NO)(CH2SiMe3)(CHSiMe3)]- from Its Neutral Dialkyl Precursor

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Differing Reactions of Functionalized Hydrocarbons with Cp*M(NO)(alkyl)(η³-allyl) Complexes of Molybdenum and Tungsten

Novel Synthetic Routes to the Anionic Alkylidene Complex [Cp*Mo(NO)(CH₂SiMe₃)(CHSiMe₃)]^- from Its Neutral Dialkyl Precursor