Crystal and molecular structure of allyl(bromo)bis(triethylphosphine)platinum(II).  An example of .sigma. bonding of an .eta.1-allyl group

Huffman, John C.; Laurent, M. P.; Kochi, J. K.

doi:10.1021/ic50176a043

Cited by 18 publications

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“…The Pd−C(23) and Pd−Cl bond distances and P−Pd−N(1) angle are similar to those in [Pd(Me)Cl( P,N )], where P,N is a six-membered ring phosphino-amine ligand . The C−C bond distances and angles within the allyl ligand are consistent with other examples of transition metal η 1 -allyl complexes described in the literature. − ,,, …”

Section: Resultssupporting

confidence: 84%

Palladium Complexes with a New Hemilabile Bis(oxazoline)phenylphosphonite Ligand. Characterization of an Unprecedented Chloro Palladium(II)−(η¹-Allyl) Complex

et al. 2001

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The coordination chemistry of the new, structurally characterized ligand bis(oxazoline)phenylphosphonite (I, abbreviated NOPON Me 2 ), shows its flexibility which is due to the possible formation of six-membered chelate rings. In the Pd(II) complexes [Pd(NCMe)-(NOPON Me 2 -N,P,N)](BF 4 ) 2 , 1 (characterized by X-ray diffraction in 1‚0.5Et 2 O‚0.33MeCN), and [PdCl(NOPON Me 2 -N,P,N)](PF 6 ), 2, this ligand behaves in a static tridentate manner, whereas in [Pd(Me)Cl(NOPON Me 2 -N,P)], 3, [PdI 2 (NOPON Me 2 -N,P)], 4, [PdCl 2 (NOPON Me 2 -N,P)], 5, and the allyl complex [Pd(η 3 -C 3 H 5 )(NOPON Me 2 -N,P)](PF 6 ), 6, it displays fluxional bidentate behavior, as shown by variable-temperature NMR studies. In 3, only the isomer in which the methyl ligand is trans to nitrogen is formed. In the related complex [Pd(η 3 -C 3 H 5 )-(NOPON Me 2 -N,P)]Cl, 7, an equilibrium has been evidenced between 7a and 7b, which involves coordination of the chloride and isomerization of the allyl ligand from η 3 to η 1 . The latter isomer is quantitatively formed in toluene at 259 K and in the solid state. This was established using NMR spectroscopy by combined variable-temperature solution and solidstate studies. Isomer 7b was also characterized by X-ray diffraction, a rare example of a fully characterized allyl η 1 -bonding mode for Pd complexes and the first in transition metal chemistry for a mutual cis arrangement of η 1 -allyl and chloride ligands, a situation relevant to intermediates involved in catalytic transformations. The tridentate coordination mode of I found in complexes 1 or 2 never occurred in the related alkyl or allyl complexes. This is consistent with the antisymbiotic effect between carbon and phosphorus donors, and this finding was confirmed by theoretical calculations. To understand whether the mutually cis disposition in 3 and 7b of the chloride ligand (trans to P) and of a σ-donor ligand such as the methyl or the η 1 -allyl ligand (trans to N) is intrinsic to the nature of these ligands or related in one way or another to the P,N heterobidentate nature and resulting asymmetry of the NOPON Me 2 ligand, DFT-B3LYP calculations were carried out on a series of isomeric structures of four-and three-coordinate chloro, methyl, and η 1 -allyl Pd(II) complexes. The existence of an energetic barrier against the formation of a compound where the phosphorus atom of tridentate NOPON Me 2 is trans to an alkyl or η 1 -allyl ligand was established.

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Section: Resultssupporting

confidence: 84%

Palladium Complexes with a New Hemilabile Bis(oxazoline)phenylphosphonite Ligand. Characterization of an Unprecedented Chloro Palladium(II)−(η¹-Allyl) Complex

et al. 2001

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“…The stereochemistry of allyl formation has been studied for many years on many different transition-metal complexes. − ,, ,, While the formation of allyl complexes from Pt(II) and allyl alcohol is unusual, the stereochemistries are typical. Table and Scheme provide a summary of the main stereochemical results.…”

Section: Resultsmentioning

confidence: 99%

Formation of [Pt(η³-allyl)(TPPTS)₂]⁺ from Reaction of cis-Pt(Cl)₂(TPPTS)₂ with Alkenols in Water

2005

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Reactions of alkenols with cis-Pt(Cl)2(TPPTS)2 (TPPTS = P(m-C6H4SO3Na)3) in water result in [Pt(η3-allyl)(TPPTS)2]+ as the exclusive platinum product with 1 equiv of oxidized alkenol. The η3-allyl is not fluxional in water, and the syn and anti isomers can be distinguished at room temperature. For 3-buten-1-ol and 4-penten-1-ol, in addition to the η3-allyl complex and oxidation of the alkene, catalytic isomerization of the alkene is observed. No reaction occurs for cis-Pt(Cl)2(P(p-tolyl)3)2, cis-Pt(Cl)(THF)(P(p-tolyl)3)2 +, or cis-Pt(THF)2(P(p-tolyl)3)2 2+ with the alkenols in THF, indicating the importance of H2O. Excess Cl- inhibits the reaction. The oxidation product is selectively deuterated. These observations are combined into a proposed mechanism.

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“…Large P−P coupling constants have been observed for trans -Mo 2 Cl 2 (NH 2 R)(PY 3 )(PY‘ 3 ), where ∠(P−Mo−P) = 155° . A 2 J PP coupling constant >500 Hz has been reported in the systems of trans -MX 2 (PY 3 )(PY‘ 3 ) (M = Pd, Pt; X = Cl, I). , The P−M−P angles here are likely greater than 170° as crystallographically found in the analogous compounds like trans -MLL‘(PY 3 ) 2 . − Many examples have been reported to show that P−P coupling is larger for trans groups than for cis. − …”

Section: Discussionmentioning

confidence: 51%

Kinetics and Mechanism of Phosphine Autoxidation Catalyzed by Imidorhenium(V) Complexes

Wei-dong

Espenson

2001

Inorg. Chem.

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The relative binding abilities of PY(3) (PMe(3), PMe(2)Ph, PMePh(2), PPh(3), P(OMe)(3), P(OMe)(2)Ph, PEt(3), P(OEt)(3), P(OEt)Ph(2), and dmpe) toward Re(V) were evaluated. The equilibrium constants for the reactions, MeRe(NAr)(2)[P(OMe)(3)](2) + PY(3) = MeRe(NAr)(2)(PY(3))(2) (1) + P(OMe)(3), decrease in the order PMe(3) > dmpe > PMe(2)Ph > P(OMe)(2)Ph approximately PEt(3) > P(OEt)(3) > PMePh(2) > P(OEt)Ph(2) > PPh(3). Both electronic and steric factors contribute to this trend. The equilibrium constant increases as the basicity of PY(3) increases when the steric demand is the same. However, steric effects play a major role in the coordination, and this is the reason that the affinity of PEt(3) toward Re(V) is less than that of PMe(2)Ph. A mixed-ligand complex, MeRe(NAr)(2)[P(OMe)(3)](PY(3)), was also observed in the course of the stepwise formation of 1. The large coupling constant, (2)J(PP) > or = 491 Hz, between the two phosphorus atoms suggests a trans geometry for the phosphines. Compound 1 catalyzes the oxidation of PY(3) by molecular oxygen. Kinetic studies suggest that the reaction of 1 with O(2) is first-order with respect to [O(2)] and inverse-first-order with respect to [PY(3)]. A mechanism involving a peroxorhenium intermediate MeRe(NAr)(2)(eta(2)-O(2)) is proposed for the catalytic processes. The reactivity of MeRe(NAr)(2)(eta(2)-O(2)) toward triaryl phosphines parallels that of the known compound MeReO(2)(eta(2)-O(2)).

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Crystal and molecular structure of allyl(bromo)bis(triethylphosphine)platinum(II). An example of .sigma. bonding of an .eta.1-allyl group

Abstract: Crystal and Molecular Structure of Allyl(bromo)bis(triethylphosphine)platinum(H). An

Cited by 18 publications

References 2 publications

Palladium Complexes with a New Hemilabile Bis(oxazoline)phenylphosphonite Ligand. Characterization of an Unprecedented Chloro Palladium(II)−(η¹-Allyl) Complex

Palladium Complexes with a New Hemilabile Bis(oxazoline)phenylphosphonite Ligand. Characterization of an Unprecedented Chloro Palladium(II)−(η¹-Allyl) Complex

Formation of [Pt(η³-allyl)(TPPTS)₂]⁺ from Reaction of cis-Pt(Cl)₂(TPPTS)₂ with Alkenols in Water

Kinetics and Mechanism of Phosphine Autoxidation Catalyzed by Imidorhenium(V) Complexes

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Crystal and molecular structure of allyl(bromo)bis(triethylphosphine)platinum(II). An example of .sigma. bonding of an .eta.1-allyl group

Abstract: Crystal and Molecular Structure of Allyl(bromo)bis(triethylphosphine)platinum(H). An

Cited by 18 publications

References 2 publications

Palladium Complexes with a New Hemilabile Bis(oxazoline)phenylphosphonite Ligand. Characterization of an Unprecedented Chloro Palladium(II)−(η1-Allyl) Complex

Palladium Complexes with a New Hemilabile Bis(oxazoline)phenylphosphonite Ligand. Characterization of an Unprecedented Chloro Palladium(II)−(η1-Allyl) Complex

Formation of [Pt(η3-allyl)(TPPTS)2]+ from Reaction of cis-Pt(Cl)2(TPPTS)2 with Alkenols in Water

Kinetics and Mechanism of Phosphine Autoxidation Catalyzed by Imidorhenium(V) Complexes

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Palladium Complexes with a New Hemilabile Bis(oxazoline)phenylphosphonite Ligand. Characterization of an Unprecedented Chloro Palladium(II)−(η¹-Allyl) Complex

Palladium Complexes with a New Hemilabile Bis(oxazoline)phenylphosphonite Ligand. Characterization of an Unprecedented Chloro Palladium(II)−(η¹-Allyl) Complex

Formation of [Pt(η³-allyl)(TPPTS)₂]⁺ from Reaction of cis-Pt(Cl)₂(TPPTS)₂ with Alkenols in Water