Binuclear Palladium Complexes with Bridging Hydrides. Unusual Coordination Behavior of LiBEt4 and NaBEt4

Fryzuk, Michael D.; Lloyd, Brian R.; Clentsmith, Guy K. B.; Rettig, Steven J.

doi:10.1021/ja00088a017

Cited by 72 publications

(49 citation statements)

References 2 publications

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“…The optimized structure of the dihydride complex 1‐H (Scheme ) shows that the two Pd centers and the two H atoms are coplanar ( θ =180°), in agreement with available crystal structures 19. Furthermore, the calculated PdH bond distances are equal, and the PdPd bond distance (2.82 Å) is significantly longer than in 1‐Si (2.62 Å).…”

Section: Methodssupporting

confidence: 81%

“…In this case, only the metal 5s orbital is available for bonding with an X orbital, which formally contains a single electron. When X is spherical, such as a hydride, either planar or slightly distorted planar geometry19 results in good overlap between X and the 5s orbitals of the Pd atoms. This arrangement generates a symmetrical bridging situation, which stabilizes the two remaining electrons.…”

Section: Methodsmentioning

confidence: 99%

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An Unusual Example of Hypervalent Silicon: A Five‐Coordinate Silyl Group Bridging Two Palladium or Nickel Centers through a Nonsymmetrical Four‐Center Two‐Electron Bond

et al. 2013

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Pd and Ni dimers supported by PSiP ligands in which two hypervalent five-coordinate Si atoms bridge the two metal centers are reported. Crystallographic characterization revealed a rare square-pyramidal geometry at Si and an unusual asymmetric M2 Si2 core (M=Pd or Ni). DFT calculations showed that the unusual structure of the core is also found in a model in which the phosphine and Si centers are not part of a pincer group, thus indicating that the observed geometry is not imposed by the PSiP ligand. NBO analysis showed that an asymmetric four-center two-electron (4c-2e) bond stabilizes the hypervalent Si atoms in the M2 Si2 core.

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Section: Methodssupporting

confidence: 81%

Section: Methodsmentioning

confidence: 99%

An Unusual Example of Hypervalent Silicon: A Five‐Coordinate Silyl Group Bridging Two Palladium or Nickel Centers through a Nonsymmetrical Four‐Center Two‐Electron Bond

et al. 2013

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“…Preparation of cationic alkyls and hydrides of Pd II We have previously reported the preparation of dinuclear hydrides of palladium() 22 and catalytically active palladium(0) 23 complexes that incorporate electron-rich chelating ligands bearing isopropyl substituents, i.e. 1,2-bis(diisopropylphosphino)ethane (dippe) and 1,3-bis(diisopropylphosphino)propane (dippp).…”

Section: Resultsmentioning

confidence: 99%

Reactivity of electrophilic palladium alkyl cations stabilized by electron-rich chelating diphosphine ligands. Evidence for dinuclear intermediates and the formation of a dinuclear mixed-valence methyl cation ‡

Fryzuk¹,

Clentsmith²,

Rettig³

1998

J. Chem. Soc., Dalton Trans.

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The reactivity of the electron-rich palladium alkyl cation, [Pd(dippe)R] ϩ BAr 4 Ϫ (dippe = 1,2-bis(diisopropylphosphino)ethane; R = η 3 -CH 2 Ph or CH 3 ; BAr 4 = {B[3,5-(F 3 C) 2 C 6 H 3 ] 4 }) with a variety of small molecules is reported. Although the benzyl cation is unreactive towards carbon monoxide and dihydrogen, the corresponding methyl cation, [Pd(dippe)Me(s)] ϩ (s = Et 2 O, THF or o-dichlorobenzene) reacts rapidly with H 2 to produce the dihydride-bridged dimer {[(dippe)Pd] 2 (µ-H) 2 } 2ϩ , and with CO to produce the dinuclear mixed-valence, cationic complex [Pd(dippe)(µ-CO)Pd(dippe)Me][BAr 4 ]. In addition, the methyl cation can abstract alkyl groups from neutral dialkyl complexes; thus, the addition of [Pd(dippe)Me(s)] ϩ to Pd(dippe)(CH 2 Ph) 2 results in the formation of the methyl benzyl derivative Pd(dippe)Me(CH 2 Ph) and the cationic benzyl cation [Pd(dippe)(η 3 -CH 2 Ph)] ϩ . Methyl group interchange is also observed for the reaction of the methyl cation with the neutral dimethyl; when [Pd(dippe)Me(s)] ϩ is mixed with Pd(dippe)( 13 CH 3 ) 2 , the carbon-13 label is immediately scrambled to the cation. These exchange reactions are suggested to occur via dinuclear intermediates. The mixed-valence dinuclear species mentioned above has been investigated in some detail; mechanistic studies have indicated that the addition of CO to [Pd(dippe)Me(s)] ϩ probably proceeds via simple substitution of the solvent by CO to generate the expected mononuclear methyl carbonyl cation [Pd(dippe)Me(CO)] ϩ , followed by migratory insertion to give the acetyl carbonyl derivative [Pd(dippe)(COMe)(CO)] ϩ . The final product is the dinuclear mixed-valence species [Pd(dippe)(µ-CO)Pd(dippe)Me][BAr 4 ], which is accompanied by the formation of acetone (Me 2 CO) and the dicarbonyl dication [Pd(dippe)(CO) 2 ] 2ϩ . Presumably, methyl transfer occurs at some stage from the methyl cation to generate the methyl-acetyl complex, Pd(dippe)Me(COMe); reductive elimination of acetone under CO from the methyl-acetyl complex produces the Pd 0 complex Pd(dippe)CO which then reacts with the starting methyl cation to generate the dinuclear mixed-valence species. Addition of CO to the mixed-valence species does not result in formation of mononuclear complexes, rather 1 equivalent of CO adds to form a new dinuclear complex with two bridging COs.

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“…We found that the iodo complex 5 is the best starting compound for the metathesis reaction. 24 Both complexes 1 or 2 can be used as starting compounds for the activation of fluorinated heterocycles, but also for fluorinated olefins. 6,9,10 Thus treatment of 1 with pentafluoropyridine yields the Rh(I) complex [Rh(4-C 5 NF 4 )(PEt 3 ) 3 ] (3) (Scheme 1).…”

Section: Discussionmentioning

confidence: 99%

Hydrodefluorination of pentafluoropyridine at rhodium using dihydrogen: detection of unusual rhodium hydrido complexes

et al. 2007

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The pentafluoropyridyl complex [Rh(4-C5NF4)(PEt3)3] (3) reacts with H2 to give initially the dihydrido complex cis-mer-[Rh(H)2(4-C5NF4)(PEt3)3] (6). Within a few hours 2,3,5,6-tetrafluoropyridine as well as two rhodium(III) complexes mer-[Rh(H)3(PEt3)3] (mer-) and fac-[Rh(H)3(PEt3)3] (fac-) are formed. A catalytic C-F activation process for the formation of 2,3,5,6-tetrafluoropyridine starting from pentafluoropyridine and dihydrogen using 3 as a catalyst has been developed. Reaction of [RhH(PEt3)3] (1) with hydrogen affords fac-[Rh(H)3(PEt3)3] (fac-7) and mer-[Rh(H)3(PEt3)3] (mer-7) in a ratio of 1 : 7.25 at 193 K. The latter complex represents the first mononuclear rhodium compound bearing trans-hydrides.

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Binuclear Palladium Complexes with Bridging Hydrides. Unusual Coordination Behavior of LiBEt4 and NaBEt4

Cited by 72 publications

References 2 publications

An Unusual Example of Hypervalent Silicon: A Five‐Coordinate Silyl Group Bridging Two Palladium or Nickel Centers through a Nonsymmetrical Four‐Center Two‐Electron Bond

An Unusual Example of Hypervalent Silicon: A Five‐Coordinate Silyl Group Bridging Two Palladium or Nickel Centers through a Nonsymmetrical Four‐Center Two‐Electron Bond

Reactivity of electrophilic palladium alkyl cations stabilized by electron-rich chelating diphosphine ligands. Evidence for dinuclear intermediates and the formation of a dinuclear mixed-valence methyl cation ‡

Hydrodefluorination of pentafluoropyridine at rhodium using dihydrogen: detection of unusual rhodium hydrido complexes

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