“Grignard‐Analogous” Rhodium Phosphane Complexes

Bogdanović, Borislav; Leitner, Walter; Six, Christian; Wilczok, Ursula; Wittmann, Klaus

doi:10.1002/anie.199705021

Cited by 27 publications

(30 citation statements)

References 32 publications

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“…10 In addition, certain metal complexes abstract oxygen readily from CO 2 , 11 but the resulting metal-oxygen bonds are necessarily strong and catalytic turnover is rare. 12 Sadighi and his coworkers have developed a way to reduce carbon dioxide to carbon monoxide by organocopper(I) complexes supported by NHC ligands with a diboron reagent. 13 Recently, Cummins et al, reported the reactions of some new terminal Ta-H complexes with CO 2 to give bimetallic methylene diolate complexes.…”

Section: Introductionmentioning

confidence: 99%

DFT study on activation of carbon dioxide by (tBuArN)3MN (MNb,V,Ta): the electronic structure and activity

2011

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The reaction mechanism for the reduction of CO(2) gas activated by (tBuArN)(3)M≡N was studied by the means of density functional theory (DFT) calculations. The calculations indicated that this reaction has a two step reaction mechanism. From our calculations, we found that (tBuArN)(3)Ta≡N held the best activity among the three (tBuArN)(3)M≡N complexes studied. Our results also indicated that the reaction of (tBuArN)(3)M≡N with CO(2) occurred under orbital control involving the HOMO-3 orbital of (tBuArN)(3)M≡N, which could give higher overlapping with the LUMO of the CO(2) molecule. The substitutions on the amino donor ligands studied here took larger effect on the HOMO structure of the (tBuArN)(3)M≡N molecules. The electronic structure of the (tBuArN)(3)M≡N complexes also showed their ability for activating CO(2) molecules, in the order of M = V < Nb < Ta.

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Section: Introductionmentioning

confidence: 99%

DFT study on activation of carbon dioxide by (tBuArN)3MN (MNb,V,Ta): the electronic structure and activity

2011

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“…A more conclusive example is provided by the example of the complexes ML 4 - , where M = Rh(1−) or Ir(1−) and L = PZ 3 or CO. These complexes are stabilized by weak donors/good π-acceptors, even when sterics are not at issue . For example, equilibrium 7 lies too far to the right to be measured spectroscopically 7e.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamics of Phosphine Coordination to the [PNP]Rh^I Fragment: An Example of the Importance of Reorganization Energies in the Assessment of Metal−Ligand “Bond Strengths”

et al. 1998

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Reaction enthalpies of the complexes [RPNP]Rh(COE) ([RPNP] ) N(SiMe 2 CH 2 PPh 2 ) 2 , N(SiMe 2 -CH 2 P i Pr 2 ) 2 ; COE ) cyclooctene) with a series of phosphine ligands and CO have been measured by solution calorimetry. The measured enthalpies span a range of ca. 40 kcal/mol. These systems favor coordination of strong π-acceptor/weak σ-donor ligands as shown by the trend in ∆H rxn : CO . Ppyrl′ 3 > Ppyrl 3 > PPhpyrl 2 > PPh 2 pyrl > PPh 3 . This trend is exactly the opposite of that observed in another square planar rhodium(I) system, trans-RhCl(CO)(PZ 3 ) 2 . With the exception of CO, the ligands investigated are isosteric, and so the observed trends are electronic in nature. Single-crystal X-ray diffraction studies on several of theses complexes ([RPNP]RhL where R, L ) Ph, PPh 3 ; Ph, Ppyrl 3 ; Ph, CO; i Pr, PPh 3 ; i Pr, Ppyrl 3 ; i Pr, CO; i Pr, COE) have been performed. Although the structural trends are readily understood in terms of the electronic (donor/acceptor) nature of each ligand array, it is not obvious that the structural data predict the trends or, in particular, the trend reversal in ∆H rxn in the two Rh(I) systems. Rather, these results illustrate the importance of reorganization energies in thermodynamic analyses of metal-ligand bonding, especially in the presence of synergistic bonding involving σ-donor, π-donor, and π-acceptor ligands, interacting through shared metal orbitals (electron pushpull). In such cases the interpretation of a metal-ligand bond dissociation enthalpy (D) as an intrinsic, universal, and transferable property of that bond (e.g., a "bond strength") is an invalid proposition.

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“…The 1 J RhÀP coupling constants are 186 and 119 Hz, which are suggestive of CÀCN bond cleavage; however, this possibility was eliminated from consideration when the reaction was repeated with 13 The major resonance at δ 163 is proposed to be an imine carbon on the basis of DEPT-135 and 1 HÀ 13 C HSQC NMR experiments. A positive signal was observed for this resonance when a DEPT-135 NMR experiment was performed, indicative of a carbon bonded to an odd number of hydrogens, and a 1 H correlation for δ 163 was found at δ 7.4 in a 1 HÀ 13 C HSQC experiment.…”

Section: Attempted Càcn Activation With [(Dippe)rh(η 6 -Ph-bph 3 )]mentioning

confidence: 97%

C–CN Bond Activation of Benzonitrile with [Rh^–I(dippe)]⁻

et al. 2011

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The complex [Rh(dippe)(μ-Cl)]2 (1) was reduced with potassium metal to produce the highly reactive Rh–I species [Rh(dippe)(μ-K·THF)]2 (2). 2 was characterized by NMR spectroscopy (31P, 1H) and IR spectroscopy after forming the derivative K[Rh(dippe)(CO)2] (2a). The C–CN bond of benzonitrile was cleaved by oxidative addition when it was reacted stoichiometrically with 2 to form the anionic Rh(I) complex K[Rh(dippe)(CN)(Ph)] (3). 3 has been characterized by NMR spectroscopy (31P, 1H, 13C), and by the use of 13C-labeled benzonitrile. C–CN bond cleavage was also attempted by reacting benzonitrile with the zwitterionic complex [Rh(dippe)(η6-Ph-BPh3)] (4). A product 5 was formed from reaction with 2 equiv of benzonitrile. Reaction with 13C-labeled benzonitrile has ruled out the possibility of C–CN cleavage in this species, and a C–H bond activation pathway is operative instead.

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“Grignard‐Analogous” Rhodium Phosphane Complexes

Cited by 27 publications

References 32 publications

DFT study on activation of carbon dioxide by (tBuArN)3MN (MNb,V,Ta): the electronic structure and activity

DFT study on activation of carbon dioxide by (tBuArN)3MN (MNb,V,Ta): the electronic structure and activity

Thermodynamics of Phosphine Coordination to the [PNP]Rh^I Fragment: An Example of the Importance of Reorganization Energies in the Assessment of Metal−Ligand “Bond Strengths”

C–CN Bond Activation of Benzonitrile with [Rh^–I(dippe)]⁻

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“Grignard‐Analogous” Rhodium Phosphane Complexes

Cited by 27 publications

References 32 publications

DFT study on activation of carbon dioxide by (tBuArN)3MN (MNb,V,Ta): the electronic structure and activity

DFT study on activation of carbon dioxide by (tBuArN)3MN (MNb,V,Ta): the electronic structure and activity

Thermodynamics of Phosphine Coordination to the [PNP]RhI Fragment: An Example of the Importance of Reorganization Energies in the Assessment of Metal−Ligand “Bond Strengths”

C–CN Bond Activation of Benzonitrile with [Rh–I(dippe)]−

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Thermodynamics of Phosphine Coordination to the [PNP]Rh^I Fragment: An Example of the Importance of Reorganization Energies in the Assessment of Metal−Ligand “Bond Strengths”

C–CN Bond Activation of Benzonitrile with [Rh^–I(dippe)]⁻