Half-Sandwich Ruthenium-Phosphine Complexes with Pentadienyl and Oxo- and Azapentadienyl Ligands

Reyna-Madrigal, Amira; Moreno-Gurrola, Anabel; Pérez‐Camacho, Odilia; Navarro-Clemente, M. Elena; Juárez-Saavedra, Patricia; Leyva‐Ramírez, Marco A.; Arif, Atta M.; Ernst, Richard D.; Paz-Sandoval, M. Ángeles

doi:10.1021/om300657z

Cited by 13 publications

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“…Over the past decade various studies on the chemistry of the pentadienyl (Pdl = C 5 H 7 ) ligand have given valuable insight into the reactivity of the Pdl ligand in comparison to the similar, and more well known, cyclopentadienyl ligand (Cp). A wide variety of Pdl ligands have been synthesized, and studies − have revealed several unique properties of Pdl, , leading to numerous possible applications of metal pentadienyl reaction chemistry. , Metal complexes containing the Pdl ligand often exhibit interesting reactivity due to the accessibility of a range of η 1 , η 3 , and η 5 bonding modes . While the Pdl ligand has an extreme tendency to bond to transition metals in low oxidation states as a result of the high δ acidities of these ligands, higher valent (≥+3) complexes have been reported. , Previous studies on Pdl ligands also show a marked reversal in the favorability of the bonding in comparison to that for the Cp ligand depending on the metal oxidation state, leading to differences in structure and reactivity of the low-valent and high-valent metal complexes. , The Pdl ligand bonds more strongly to a metal center than does a Cp ligand in lower valent metal complexes, and the reverse is observed for high-valent metal complexes.…”

Section: Introductionmentioning

confidence: 99%

Phosphine-Substituted (η⁵-Pentadienyl) Manganese Carbonyl Complexes: Geometric Structures, Electronic Structures, and Energetic Properties of the Associative Substitution Mechanism, Including Isolation of the Slipped η³-Pentadienyl Associative Intermediate

et al. 2013

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The molecule (η5-Me2Pdl)Mn(CO)3 (η5-Me2Pdl = 2,4-dimethyl-η5-pentadienyl) has been prepared by a new method and used as a starting material to prepare the molecules (η5-Me2Pdl)Mn(CO) n (PMe3)3–n (n = 2, 1) by phosphine substitution for carbonyls. The first carbonyl substitution is achieved thermally in refluxing cyclohexane, and the second carbonyl substitution requires photolysis. At room temperature in benzene the associative intermediate (η3-Me2Pdl)Mn(CO)3(PMe3) that precedes the initial loss of carbonyl is observed. Single-crystal structures are reported for all complexes, including the associative intermediate of the first substitution in which the pentadienyl ligand has slipped to the η3 bonding mode. These molecules offer an opportunity to examine fundamental principles of the interactions between metals and pentadienyl ligands in comparison to the well-developed chemistry of metal cyclopentadienyl (Cp) complexes as a function of electron richness at the metal center. Photoelectron spectra of these molecules show that the Me2Pdl ligand has π ionizations at energy lower than that for the analogous Cp ligand and donates more strongly to the metal than the Cp ligand, making the metal more electron rich. Phosphine substitutions for carbonyls further increase the electron richness at the metal center. Density functional calculations provide further insight into the electronic structures and bonding of the molecules, revealing the energetics and role of the pentadienyl slip from η5 to η3 bonding in the early stages of the associative substitution mechanism. Computational comparison with dissociative ligand substitution mechanisms reveals the roles of dispersion interaction energies and the entropic free energies in the ligand substitution reactions. An alternative scheme for evaluating the computational translational and rotational entropy of a dissociative mechanism in solution is offered.

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Section: Introductionmentioning

confidence: 99%

Phosphine-Substituted (η⁵-Pentadienyl) Manganese Carbonyl Complexes: Geometric Structures, Electronic Structures, and Energetic Properties of the Associative Substitution Mechanism, Including Isolation of the Slipped η³-Pentadienyl Associative Intermediate

et al. 2013

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“…Treatment of compound 7 with 1 equivalent of triflic acid in diethyl ether leads to the formation of dark red 8 , the monoprotonation product. The NMR spectra of 8 indicate that it is a single isomer in which protonation has occurred at the iridium center and the azapentadienyl ligand has coordinated in an unusual η 3 , η 1 fashion involving both its allyl moiety and its nitrogen lone pair (see Scheme ) . In the 1 H NMR spectrum, the metal hydride signal is observed at δ −28.79 and is a doublet of doublets due to coupling to two inequivalent PEt 3 ’s.…”

Section: Resultsmentioning

confidence: 99%

Synthesis, Spectroscopy, Structure, and Reactivity of Azapentadienyl-Rhodium-Phosphine and Azapentadienyl-Iridium-Phosphine Complexes1

2013

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We report the synthesis, spectroscopy, structure, and reactivity of (1,2,3-η 3 )-(5-tert-butylazapentadienyl)Rh-(PMe 3 ) x (1, x = 2; 4, x = 3) and (1,2,3-η 3 )-(5-tert-butylazapentadienyl)Ir(PEt 3 ) x (7, x = 2; 12, x = 3), which are produced by reacting [(cyclooctene) 2 M(μ-Cl)] 2 with the appropriate amount of phosphine, followed by potassium tert-butylazapentadienide. Each of these compounds reacts with 1 equivalent of triflic acid to produce a monoprotonation product. Rhodium compounds 1 and 4 react at nitrogen to produce 2 and 5, respectively. Iridium compound 7 reacts at the metal center, generating an iridiumhydride product, 8, in which the azapentadienyl ligand coordinates in an unusual η 3 , η 1 -fashion, while compound 12 reacts at nitrogen to produce 13. The monoprotonation products have been treated with additional acid, and in each case the secondary site of electrophilic addition has been determined. Rhodium compounds 2 and 5 both react with a second equivalent of triflic acid at the metal center to produce unstable metal-hydrides. These species reductively eliminate protonated tertbutylcrotonaldimine and ultimately produce isolable octahedral Rh(III) complexes 3 and 6 after addition of a third equivalent of triflic acid. In contrast, when iridium compound 8 is treated with a second equivalent of triflic acid, addition occurs at nitrogen to produce diprotonation product 9. Similarly, 13 reacts with a second equivalent of acid at nitrogen, generating a product with a diprotonated nitrogen, 14. All of the compounds reported herein have been identified by NMR, while the structures of 2, 4, 5, 6, 12, 13, and 14 have been confirmed by single-crystal X-ray diffraction.

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“…It should be noted that 4a and 4b represent, to the best of our knowledge, the first structurally characterised half-sandwich pentadienyl ruthenium complexes with a (formal) electron count of 16, and previously described pentadienyl species are usually 18-electron complexes with common three-legged piano-stool ( pseudo-tetrahedral) geometries. 16,19,27,28 29,30 In contrast, a significantly larger number of 16-electron complexes are known that contain the sterically more demanding (η 5 -C 5 Me 5 )Ru fragment. [31][32][33] Fig.…”

Section: Preparation and Electronic Structure Of The Half-open Ruthen...mentioning

confidence: 99%

16-Electron pentadienyl- and cyclopentadienyl-ruthenium half-sandwich complexes with bis(imidazol-2-imine) ligands and their use in catalytic transfer hydrogenation

et al. 2015

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Bis(η(5)-2,4-dimethylpentadienyl)ruthenium(II), [(η(5)-C7H11)2Ru] (1, “open ruthenocene”), which has become accessible in high yield and large quantities via an isoprene-derived diallyl ruthenium(IV) complex, can be converted into the protonated open ruthenocene 2 by treatment with HBF4 and subsequently into the protonated half-open ruthenocene 3 by reaction with cyclopentadiene. The electronic structure of 3 was studied by DFT methods, revealing that the CH-agostic complex [(η(5)-C5H5)Ru{(1-4η)-C7H12-η(2)-C(5),H(5)}]BF4 (A) represents the global minimum, which is 3.7 kcal mol(−1) lower in energy than the hydride complex [(η(5)-C5H5)RuH(η(5)-C7H11)]BF4 (B). 2 and 3 were treated with the ligands N,N′-bis(1,3,4,5-tetramethylimidazolin-2-ylidene)-1,2-ethanediamine (BL(Me)) and N,N′-bis(1,3-diisopropyl-4,5-dimethylimidazolin-2-ylidene)-1,2-ethanediamine (BL(iPr)) to afford the cationic 16-electron pentadienyl and cyclopentadienyl complexes [(η(5)-C7H11)Ru(BL(R))]BF4 (4a, R = Me; 4b, R = iPr) and [(η(5)-C5H5)Ru(BL(R))]BF4 (5a, R = Me; 5b, R = iPr). All complexes catalyse the transfer hydrogenation of acetophenone in isopropanol, and the most active complex 4a in this reaction was employed for the hydrogenation of a broader range of aliphatic and aromatic ketones.

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Half-Sandwich Ruthenium-Phosphine Complexes with Pentadienyl and Oxo- and Azapentadienyl Ligands

Cited by 13 publications

References 80 publications

Phosphine-Substituted (η⁵-Pentadienyl) Manganese Carbonyl Complexes: Geometric Structures, Electronic Structures, and Energetic Properties of the Associative Substitution Mechanism, Including Isolation of the Slipped η³-Pentadienyl Associative Intermediate

Phosphine-Substituted (η⁵-Pentadienyl) Manganese Carbonyl Complexes: Geometric Structures, Electronic Structures, and Energetic Properties of the Associative Substitution Mechanism, Including Isolation of the Slipped η³-Pentadienyl Associative Intermediate

Synthesis, Spectroscopy, Structure, and Reactivity of Azapentadienyl-Rhodium-Phosphine and Azapentadienyl-Iridium-Phosphine Complexes1

16-Electron pentadienyl- and cyclopentadienyl-ruthenium half-sandwich complexes with bis(imidazol-2-imine) ligands and their use in catalytic transfer hydrogenation

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Half-Sandwich Ruthenium-Phosphine Complexes with Pentadienyl and Oxo- and Azapentadienyl Ligands

Cited by 13 publications

References 80 publications

Phosphine-Substituted (η5-Pentadienyl) Manganese Carbonyl Complexes: Geometric Structures, Electronic Structures, and Energetic Properties of the Associative Substitution Mechanism, Including Isolation of the Slipped η3-Pentadienyl Associative Intermediate

Phosphine-Substituted (η5-Pentadienyl) Manganese Carbonyl Complexes: Geometric Structures, Electronic Structures, and Energetic Properties of the Associative Substitution Mechanism, Including Isolation of the Slipped η3-Pentadienyl Associative Intermediate

Synthesis, Spectroscopy, Structure, and Reactivity of Azapentadienyl-Rhodium-Phosphine and Azapentadienyl-Iridium-Phosphine Complexes1

16-Electron pentadienyl- and cyclopentadienyl-ruthenium half-sandwich complexes with bis(imidazol-2-imine) ligands and their use in catalytic transfer hydrogenation

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Phosphine-Substituted (η⁵-Pentadienyl) Manganese Carbonyl Complexes: Geometric Structures, Electronic Structures, and Energetic Properties of the Associative Substitution Mechanism, Including Isolation of the Slipped η³-Pentadienyl Associative Intermediate

Phosphine-Substituted (η⁵-Pentadienyl) Manganese Carbonyl Complexes: Geometric Structures, Electronic Structures, and Energetic Properties of the Associative Substitution Mechanism, Including Isolation of the Slipped η³-Pentadienyl Associative Intermediate