Synthesis, Structure, and Reactivity of Niobium and Tantalum Alkyne Complexes

Parker, Kyle D. J.; Fryzuk, Michael D.

doi:10.1021/om5010385

Cited by 57 publications

(33 citation statements)

References 113 publications

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“…3), have been widely discussed, in particular by comparison with  2 -alkene ligands [110,111]. The four-electron ,-donor ability of alkynes has been demonstrated in metallacyclopropene complexes of group 4 and 5 metals [112,113]. In the titanocene series, for example ( Fig.…”

Section:  2 -Alkyne π-Complexesmentioning

confidence: 99%

On the nature of the dative bond: Coordination to metals and beyond. The carbon case

Lepetit

Maraval

Canac

et al. 2016

Coordination Chemistry Reviews

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Section:  2 -Alkyne π-Complexesmentioning

confidence: 99%

On the nature of the dative bond: Coordination to metals and beyond. The carbon case

Lepetit

Maraval

Canac

et al. 2016

Coordination Chemistry Reviews

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“…The insertion of unsaturated molecule into a metal–hydride bond is considered a fundamental chemical step in several catalytic cycles and frequently leads to reactive intermediates . In particular, the insertion of an alkyne into transition metal–hydrogen bond is a key elementary step in catalytic polymerization and hydrogenation processes, which has received considerable attention …”

Section: Introductionmentioning

confidence: 99%

Stereoselectivity and nonmigratory insertion mechanism of dimethylacetylene dicarboxylate into metallocene‐hydride of Cp₂M(L)H [Cp =η⁵‐C₅H₅; M = Nb, V; L = CO, P (OMe)₃]: A DFT study

Huo

Zeng

et al. 2020

Applied Organom Chemis

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The insertion of an alkyne into transition metal–hydrogen bonds is a key elementary step in catalytic polymerization and hydrogenation processes. It was found that a (Z)‐ or (E)‐type alkyenyl complex can be formed through trans/cis stereospecific processes. In this work, the reaction mechanism of Cp2M(L)H [Cp = η5‐C5H5; M = Nb, V; L = CO, P (OMe)3] with dimethylacetylene dicarboxylate (DMAD), and the factors influencing the stereoselectivity have been investigated based on density functional theory calculations. The calculated results show that all of the reactions are exothermic. For L = CO, the Z‐isomer product forms first even at low temperatures because of the low Gibbs free energy barrier (ΔG#). Then the Z‐pro converts to E‐pro, while for L = P (OMe)3, the exclusive product is the E‐isomer. For different metal centers, the reaction mechanisms of the Cp2M(CO)H + DMAD (M = Nb and V) reaction are similar, while their products are different at room temperature. For M = Nb, because the energy barrier of the isomerization from Z‐pro to E‐pro is low and the relative free energies of Z‐pro and E‐pro are almost equal, both Z‐pro and E‐pro can be obtained. While for the Cp2V(CO)H + DMAD reaction, only the Z‐pro can be obtained under mild conditions, E‐pro can be obtained only at high temperatures. For the Cp2M(CO)H+DMAD(M=V and Nb) reactions, the formation of E‐isomer products proceeds via two five‐membered ring transition states. The calculated results provide an reasonable explanation for the experimental results and predict a new insertion reaction.

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“…Recently, the synthesis and characterization of metal alkyne complexes have been reported by some groups . The reactivity, stereochemistry, and mechanism of alkyne or alkene insertion into ME bonds have also received increasingly more attention.…”

Section: Introductionmentioning

confidence: 99%

“…Even the ( E )‐alkenyl isomers have two forms, namely, antiperiplanar and synperiplanar conformers . The migratory mechanism involves a four‐center (MCCH) transition state, which occurs from the coordination of the unsaturated CC bond to the M center and its subsequent insertion into the MH bond …”

Section: Introductionmentioning

confidence: 99%

“…The first example of alkyne insertion into the MH bond in experiment is the reaction of Cp 2 TaH 3 with the esters RO 2 CCCCO 2 R (RMe, SiMe 3 ), which are activated alkynes containing two electron‐withdrawing substituents that inserted into the TaH bond in trans form to give an alkenyl‐dihydride intermediate and following a subsequent rearrangement to give the ( E )‐type hydride complex Cp 2 Ta(H)( E RO 2 CCHCHCO 2 R). The ( Z )‐type hydride complexes have not been obtained yet . By now, the reaction mechanism and stereoselective process by which the ( E )‐type hydride complex occurs are unclear.…”

Section: Introductionmentioning

confidence: 99%

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Mechanism and Stereoselectivity of the Elementometalation Process of Activated Alkyne RCCR(RCO₂Me) by Cp₂TaH₃

Wang

Zheng

et al. 2019

J Comput Chem

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The elementometalation process is a fundamental chemical step in several catalytic cycles. In this work, density functional theory computations have elucidated the detailed elementometalation mechanism of activated alkyne RCCR(RCO2Me) by Cp2TaH3 and rationalized the selectivity in experimental findings. The calculated results show that in the formation process of (E)‐olefin monohydride((E)‐Pro), the Gibbs free energy barrier is low and the entire reaction is spontaneous and exothermic; thus, (E)‐Pro can be formed easily. The formation of (Z)‐η2‐olefin monohydride complex ((Z)‐Pro) is difficult due to its high Gibbs free energy barrier. The formation process (E)‐Pro consists of the following five steps: hydride H1‐shift, conformational isomerism 1, hydride H2‐shift, conformational isomerism 2, and olefin coordination process. Topological analysis shows that there is a five‐membered ring plane structure in the reaction pathway and that the final product (E)‐Pro belongs to a typical η2‐olefin monohydride complex. Our calculated results provide an explanation for experimental observations and useful insights for further development of olefin functionalization. © 2019 Wiley Periodicals, Inc.

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Synthesis, Structure, and Reactivity of Niobium and Tantalum Alkyne Complexes

Cited by 57 publications

References 113 publications

On the nature of the dative bond: Coordination to metals and beyond. The carbon case

On the nature of the dative bond: Coordination to metals and beyond. The carbon case

Stereoselectivity and nonmigratory insertion mechanism of dimethylacetylene dicarboxylate into metallocene‐hydride of Cp₂M(L)H [Cp =η⁵‐C₅H₅; M = Nb, V; L = CO, P (OMe)₃]: A DFT study

Mechanism and Stereoselectivity of the Elementometalation Process of Activated Alkyne RCCR(RCO₂Me) by Cp₂TaH₃

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Synthesis, Structure, and Reactivity of Niobium and Tantalum Alkyne Complexes

Cited by 57 publications

References 113 publications

On the nature of the dative bond: Coordination to metals and beyond. The carbon case

On the nature of the dative bond: Coordination to metals and beyond. The carbon case

Stereoselectivity and nonmigratory insertion mechanism of dimethylacetylene dicarboxylate into metallocene‐hydride of Cp2M(L)H [Cp =η5‐C5H5; M = Nb, V; L = CO, P (OMe)3]: A DFT study

Mechanism and Stereoselectivity of the Elementometalation Process of Activated Alkyne RCCR(RCO2Me) by Cp2TaH3

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Stereoselectivity and nonmigratory insertion mechanism of dimethylacetylene dicarboxylate into metallocene‐hydride of Cp₂M(L)H [Cp =η⁵‐C₅H₅; M = Nb, V; L = CO, P (OMe)₃]: A DFT study

Mechanism and Stereoselectivity of the Elementometalation Process of Activated Alkyne RCCR(RCO₂Me) by Cp₂TaH₃