Ligand Redistribution Reactions of Five-Coordinate d6 Species: RuHX(CO)P2, IrH2XP2, and Cp*RuXP

Poulton, Jason T.; Hauger, Bryan E.; Kuhlman, Roger L.; Caulton, Kenneth G.

doi:10.1021/ic00093a021

Cited by 11 publications

(14 citation statements)

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“…The key point of the mechanism presented is the formation of octahedral ruthenium complexes in which the cis position of the Ru−SiR 3 and Ru−H bonds with respect to π-bonded styrene and vinylsilane, respectively, is necessary for the observed insertion. However, spectroscopic and X-ray determination of the structure of five-coordinate complexes of the formulas RuCl(SiR 3 )(CO)(PPh 3 ) 2 and RuHCl(CO)(PR 3 ) 2 a,b showed their approximately square-pyramidal geometry with the silyl ligand and the hydride ligand, respectively, at the apical positions and the triphenylphosphine ligands arranged mutually trans . According to these data, the attack of the olefin (styrene and vinylsilane) should readily lead to the olefin binding trans to the hydride ( 4 ) or silyl ( 5 ) ligands, respectively, so these isomers would not easily lead to the insertion of the CC bond of the examined olefins into the Ru−Si and Ru−H bond.…”

Section: Resultsmentioning

confidence: 99%

“…In this isomer, the hydride is at the cis position to the empty site, i.e., to the incoming silylolefin in a square pyramid. On the other hand, according to the considerations of Caulton at al 11c. the five-coordinate energy surface implies that attack of an incoming ligand (e.g., vinylsilane) is facile via direction a (in the HRu(CO) plane of complex 4).…”

Section: Resultsmentioning

confidence: 99%

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Silylation of Styrene with Vinylsilanes Catalyzed by RuCl(SiR₃)(CO)(PPh₃)₂ and RuHCl(CO)(PPh₃)₃

1997

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The coupling reaction of styrene with vinylsilanes catalyzed by ruthenium complexes was investigated. RuHCl(CO)(PPh3)3 (I) and RuCl(SiR3)(CO)(PPh3)2 (where R3 = Me3 (II), Me2Ph (III), (EtO)3 (IV)) were found to be efficient and selective catalysts for the formation of E-1-phenyl-2-silylethene and evolution of ethene. Stoichiometric reactions of styrene with the Ru−Si bonds of II−IV in argon and silylstyrene with the Ru−H bond in air (I*) as well as a MS study of the product of the deuterated styrene with vinylsilanes are convincing evidence for the mechanism of the process involving the migratory insertion of styrene into the Ru−Si bond (and vinylsilane into Ru−H bond) followed by β-H (and β-Si) elimination to give phenylsilylethene (and ethene). Kinetic tests (TOF) indicate a prior dissociation of the PPh3 molecule (or by its oxygenation) from I to yield pentacoordinated RuHCl(CO)(PPh3)2 which is almost as active as II.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Silylation of Styrene with Vinylsilanes Catalyzed by RuCl(SiR₃)(CO)(PPh₃)₂ and RuHCl(CO)(PPh₃)₃

1997

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“…The large phosphine ligands in these complexes are employed to prevent dimer formation. However, halide bridges have been shown in similar complexes to mediate halide exchange reactions . If dimerization is rapid and reversible on the NMR time scale, then an AB 2 pattern should still be observed for these trihydrides.…”

Section: Resultsmentioning

confidence: 99%

“…However, halide bridges have been shown in similar complexes to mediate halide exchange reactions. 35 If dimerization is rapid and reversible on the NMR time scale, then an AB 2 pattern should still be observed for these trihydrides. However, the observed coupling would have contributions from both the monomeric complex and the dimeric complex, as shown in eq 12, where values are mole fractions and J values are coupling constants of individual configurations (eq 13).…”

Section: Methodsmentioning

confidence: 99%

Quantum Exchange Coupling: A Hypersensitive Indicator of Weak Interactions

et al. 1997

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Os(H) 3 ClL 2 (L ) P i Pr 3 ) forms a 1:1 adduct with L′ ) PEt 3 , NH 3 , MeCN, acetone, methanol, and THF. The case L′ ) PEt 3 permits the clearest identification of adduct structure as pentagonal bipyramidal. For NH 3 and MeCN, the respective kinetics of L′ loss are measured as ∆H q ) 20.7(3) and 17.6(3) kcal/mol and ∆S q ) 16(1) and 14.7(9) cal/(mol K). For acetone, methanol, and THF, the following respective ∆H°and ∆S°values for L′ binding are measured: ∆H°) -10.4(1), -6.66(8), and -5.8(2) kcal/mol; ∆S°) -41.8(5), -25.5(3), and -33(1) cal/(mol K). Decoalesced 1 H NMR spectra are reported for several of these Os(H) 3 ClL 2 L′ species, and they show a variety of examples of quantum exchange coupling among the hydride ligands. The values of J ex are higher when L′ is a more weakly-binding ligand. The quantum exchange coupling constants of Os(H) 3 XL 2 (X ) Cl, Br, I, OCH 2 CF 3 , OCH(CF 3 ) 2 ) in CD 2 Cl 2 , in toluene, and in methylcyclohexane show an unprecedented decrease of J with increasing temperature, which is attributed to weak formation of Os(H) 3 Cl(solvent)L 2 adducts at low temperature. For L′ ) CO, adduct formation leads to liberation of coordinated H 2 . Excess L′ ) MeCN or NH 3 slowly leads to formation of [Os(H) 3 L′ 2 L 2 ]Cl; the X-ray structure for L′ ) NH 3 is reported. Crystal data (-171°C): a ) 11.561(4) Å, b ) 14.215(5) Å, c ) 8.851(3) Å, R ) 97.51(2)°, ) 107.73(2)°, γ ) 104.47(2)°, with Z ) 2 in space group P1 h. The potential energy was calculated for exchange of 2H of OsH 3 X(PH 3 ) 2 L (X ) Cl with L ) no ligand and PH 3 , X ) I with L ) no ligand) using effective core potential ab initio methods at the MP2 level. The site exchange is found to be energetically easier for Cl than for I, in agreement with experiment. The hydride site exchange in the sevencoordinate species OsH 3 Cl(PH 3 ) 3 (a model for coordination of either ligand or solvent to Os) is found to be easier than that in the 16-electron species. No dihydrogen ligand is located on the reaction path for site exchange. The current theory which relates quantum exchange to a tunneling effect was used for calculating J ex as a function of temperature. The dynamic study was done using several sets of coordinates, in particular the rotation angle φ and the internuclear distance r between the exchanging H. The vibrational levels have been calculated and the symmetry of each level assigned within the permutation group in order to determine the nature of the nuclear spin function associated with each level. It is found that the rotation, φ, gives rise to the largest tunneling effect but that r cannot be neglected. The influence of the temperature, J ex (T), was included by a Boltzmann distribution. The results are in qualitative agreement with experiment in that quantum exchange coupling is larger in the case of Cl than in the case of I. Additional ligand L increases the value of the quantum exchange coupling mostly by lowering the activation energy for pairwise exchange.

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“…We have been exploring the ability of ligands containing lone pairs of electrons on their alpha atom to donate such electrons into otherwise empty metal orbitals. − This subject includes the entire range of molecules traditionally termed unsaturated (16- or 14-valence electrons), such as IrCl(CO)L 2 , RhClL 3 , RuHCl(PPh 3 ) 3 , Os(H) 2 Cl 2 (P i Pr 3 ) 2 , RuCl(Ph 2 PC 2 H 4 PPh 2 ) 2 + , Rh(PPh 3 ) 3 + , etc. We have studied potential π-donor ligands that extend from halide to amide, alkoxide, siloxide, and thiolate …”

Section: Introductionmentioning

confidence: 99%

Phosphine Dissociation Mediates C−H Cleavage of Fluoroarenes by OsH(C₆H₅)(CO)(P^tBu₂Me)₂

et al. 1999

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OsH(Ph)(CO)L 2 (L ) P t Bu 2 Me, Ph ) C 6 H 5 ) is synthesized and studied by spectroscopic and DFT (B3LYP) calculations. It forms 1:1 adducts with CO or MeCN, but D 2 causes reductive elimination of C 6 H 6 . Reaction with C 6 D 6 gives exclusively OsD(C 6 D 5 )(CO)L 2 . Lack of conversion of OsD(C 6 H 5 )(CO)L 2 to OsH-(C 6 H 4 D)(CO)L 2 under the same conditions indicates that zerovalent Os(η 2 -C 6 H 5 D)(CO)L 2 is not kinetically relevant. DFT calculations confirm that an η 2 -arene complex is not accessible and also show that the dissociatiVe reductive elimination of arene is a high energy process. Reaction of OsH(Ph)(CO)L 2 with fluorinated arenes, HAr F gives benzene and OsH(Ar F )(CO)(P t Bu 2 Me) 2 (i.e., attack on the HAr F C-H bond), with the fastest attack involving more heavily fluorinated arenes (but C 6 F 6 does not react) and the attack occurring preferentially at the C-H bond ortho to fluorine. DFT calculations show that the observed isomer is thermodynamically controlled. These results, isotope-labeling results, and rate suppression and exchange involving added free phosphine lead to a mechanism where reagent arene associates with OsH(Ph)(CO)L 2 , but benzene loss demands preliminary dissociation of phosphine from such an adduct.

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Ligand Redistribution Reactions of Five-Coordinate d6 Species: RuHX(CO)P2, IrH2XP2, and Cp*RuXP

Cited by 11 publications

References 1 publication

Silylation of Styrene with Vinylsilanes Catalyzed by RuCl(SiR₃)(CO)(PPh₃)₂ and RuHCl(CO)(PPh₃)₃

Silylation of Styrene with Vinylsilanes Catalyzed by RuCl(SiR₃)(CO)(PPh₃)₂ and RuHCl(CO)(PPh₃)₃

Quantum Exchange Coupling: A Hypersensitive Indicator of Weak Interactions

Phosphine Dissociation Mediates C−H Cleavage of Fluoroarenes by OsH(C₆H₅)(CO)(P^tBu₂Me)₂

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Ligand Redistribution Reactions of Five-Coordinate d6 Species: RuHX(CO)P2, IrH2XP2, and Cp*RuXP

Cited by 11 publications

References 1 publication

Silylation of Styrene with Vinylsilanes Catalyzed by RuCl(SiR3)(CO)(PPh3)2 and RuHCl(CO)(PPh3)3

Silylation of Styrene with Vinylsilanes Catalyzed by RuCl(SiR3)(CO)(PPh3)2 and RuHCl(CO)(PPh3)3

Quantum Exchange Coupling: A Hypersensitive Indicator of Weak Interactions

Phosphine Dissociation Mediates C−H Cleavage of Fluoroarenes by OsH(C6H5)(CO)(PtBu2Me)2

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Silylation of Styrene with Vinylsilanes Catalyzed by RuCl(SiR₃)(CO)(PPh₃)₂ and RuHCl(CO)(PPh₃)₃

Silylation of Styrene with Vinylsilanes Catalyzed by RuCl(SiR₃)(CO)(PPh₃)₂ and RuHCl(CO)(PPh₃)₃

Phosphine Dissociation Mediates C−H Cleavage of Fluoroarenes by OsH(C₆H₅)(CO)(P^tBu₂Me)₂