Synthesis and Structure of New (Polyphosphane)ruthenium Complexes with the Hemilabile Ligand 2‐(Diphenylphosphanyl)‐1‐methyl‐1H‐imidazole − An Unexpected Rearrangement of [RuCl2(PN)(PPh3)2]

Espino, Gustavo; Jalón, Félix A.; Maestro, Miguel A.; Manzano, Blanca R.; Pérez-Manrique, Mercedes; Bacigalupe, Ana C.

doi:10.1002/ejic.200300892

Cited by 16 publications

(8 citation statements)

References 58 publications

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“…By simulating the appearance of that portion of the spectrum for the four imidazole aromatic hydrogens, we determined for the site exchange of chelating and nonchelating imidazoles the following parameters: E a = 6 ± 2 kcal mol -1 and Δ S ⧧ = −6 ± 4 cal mol -1 K -1 . We are aware of only a single recent report on such a process in imidazolylphosphine complexes, however, without data on the activation parameters . There are a few examples in pyrid-2-ylphosphine chemistry of complexes with one chelating and one nonchelating phosphine, some without exchange − and others with some evidence of exchange. − There are examples of other hemilabile Pd complexes, for example ones with pyridylphosphines in which the heterocycle and the phosphine are separated by several atoms, − or complexes with phosphines containing ethers as well as other functional groups …”

Section: Resultsmentioning

confidence: 99%

“…Ligands with three imidazole groups have been used as tridentate (N) 3 ligands, bioinorganic models for three histidines in a protein. − In these species the phosphorus is not bound to the metal and only serves as a connecting element. There have been a few reports of imidazolylphosphines as bridging ligands, − bound through both P and N, but fewer of mononuclear complexes such as the ones described in this paper. − …”

Section: Introductionmentioning

confidence: 86%

“…[60][61][62][63][64] In these species the phosphorus is not bound to the metal and only serves as a connecting element. There have been a few reports of imidazolylphosphines as bridging ligands, [65][66][67][68][69][70][71][72][73] P and N, but fewer of mononuclear complexes such as the ones described in this paper. [71][72][73][74][75][76][77] Our interest in imidazolylphosphines stems from our 2001 report 75 of a catalyst for anti-Markovnikov hydration of terminal alkynes to aldehydes which was more than 90 times faster than the best catalyst reported elsewhere in the literature.…”

Section: Introductionmentioning

confidence: 99%

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Changes in Coordination of Sterically Demanding Hybrid Imidazolylphosphine Ligands on Pd(0) and Pd(II)

et al. 2005

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Low-coordinate organometallic complexes are important in structure and catalysis, and hemilability or secondary interactions such as hydrogen bonding enabled by hybrid ligands are receiving increasing attention. To study the factors controlling these phenomena, three new imidazol-2-ylphosphine ligands, L, were made. In these ligands, the bulk around P and the hindrance at the basic and potentially coordinating imidazole N-3 were varied. Remarkably, L(2)Pd(0) complexes 3a-c were shown to be two-coordinate, 12-electron species, despite the availability of imidazole N-3 to enter into eta(2)-P,N chelation. In oxidative additions of C-X bonds to the Pd(0) complexes, reaction rates and products could be controlled by the nature of the C and X groups and the R groups on the phosphine. Most significantly, whereas 4c-PhI and 4c-MeOTf from 3c are normal trans-bis(phosphine)Pd(R)(X) species, 5a-PhI, 5a-PhBr, and 5b-PhI from 3a and 3b were shown by X-ray diffraction to be a monomeric species with a single eta(2)-P,N-chelating phosphine. From 3a and methyl triflate, an ionic complex [6a-Me](+)[OTf](-) with one chelating and one nonchelating phosphine was formed, with temperature-dependent windshield-wiper exchange of the two, showing hemilability. Thus, large phosphine substituents (R = tert-butyl rather than isopropyl) favor chelation. The chelate Pd-imidazole N-3 bond is longer when the heterocyclic nitrogen is hindered by an adjacent tert-butyl group at C-4 (comparing 5a-PhI and 5b-PhI). Finally, whereas in [8b-Ph](+)[OTf](-) from 5b-PhI and isopropylamine, the amine coordinates without chelate opening or hydrogen bonding, in [10c-Me](+)[OTf](-) made from 4c-MeOTf and isopropylamine, the amine is not only coordinated at N but also donates a hydrogen bond to each phosphine imidazol-2-yl substituent.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

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Changes in Coordination of Sterically Demanding Hybrid Imidazolylphosphine Ligands on Pd(0) and Pd(II)

et al. 2005

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“…It has also been reported the preparation of Pd(0) and Pd(II) complexes with new bulky imidazolylphosphines [13]. In a previous paper we also described the synthesis and characterization of new Ru derivatives that contain the dpim ligand in the three possible coordination modes: monodentate, bidentate chelate and bridging [14]. In the work described here we decided to explore the coordination possibilities of the dpim ligand in palladium complexes in an effort to obtain information about its hemilabile behaviour.…”

Section: Introductionmentioning

confidence: 92%

Synthesis and structure of new palladium complexes with the ligand 2-(diphenylphosphino)-1-methylimidazole: Evidence of hemilability

Diez

Espino

Jalón

et al. 2007

Journal of Organometallic Chemistry

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“…This compound was first reported in 1993, although a more convenient synthetic route was subsequently published in 2001 . Some complexes of late transition metals with the dpim ligand have been described, , and we have reported new ruthenium derivatives containing this ligand in the three possible coordination modes: monodentate, bidentate chelate, and bridge . When coordinated as a bidentate system, the relative 1,3-positions of the donor atoms in the dpim ligand are associated with a strained angle in the metallacycle after κ 2 -coordination, a situation that could favor partial decoordination of this ligand.…”

Section: Introductionmentioning

confidence: 96%

Ruthenium Arene Derivatives with PN Hemilabile Ligands. P−C Cleavage and Phosphine to Phosphinite Transformation

et al. 2004

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Complexes of formula [RuCl 2 (arene)(κ 1 -dpim)] (dpim ) 2-(diphenylphosphino)-1-methylimidazole) (arene ) p-cymene, 1a; C 6 H 6 , 1b) were prepared by the reaction of [RuCl 2 (pcymene)] 2 or [RuCl 2 (C 6 H 6 )(CH 3 CN)] with dpim. Complexes 1a and 1b were structurally characterized by NMR spectroscopy and X-ray diffraction. The reaction of these precursors with BF 4salts led, in dichloromethane, to cationic complexes of formula [RuCl(arene)(κ 2dpim)]BF 4 (arene ) p-cymene, 2a; C 6 H 6 , 2b). However, in methanol the products were unexpected phosphinite derivatives of the type [RuCl(arene)(HImMe){κ 1 -PPh 2 (OMe)}]A (A ) BF 4 , arene ) p-cymene, 3a; C 6 H 6 , 3b; A ) BPh 4 , arene ) p-cymene, 3d) (ImMe ) methylimidazole). This transformation implies the existence of an easy P-C bond cleavage and phosphine functionalization with methanol at room temperature. The precursors 1a,b or the analogous derivative with 2-(diphenylphosphino)pyridine (PPh 2 py), [RuCl 2 (p-cymene)-(κ 1 -PPh 2 py)], 1c, reacted with HBF 4 to give cationic derivatives by protonation of the imidazole or the pyridine fragment, [RuCl 2 (arene)(κ 1 -PNH)]BF 4 (PNH ) dpimH, arene ) p-cymene, 4a; C 6 H 6 , 4b; PNH ) PPh 2 pyH, arene ) p-cymene, 4c). In these compounds the existence of an asymmetric and bifurcated hydrogen bond NH‚‚‚Cl 2 has been structurally determined (even by X-ray studies for 4a,b). Complexes 2a and 4a also yield the corresponding and analogous phosphinite derivatives in the presence of methanol-d 4 but at a markedly slower rate. NMR and spectrophotometric studies provided information concerning the formation of the phosphinite derivatives. It was concluded that the phosphine is not functionalized if it is not coordinated and that, very probably, a methanol solvatesintermediate between 1a and 2asparticipates in the P-C bond cleavage and allows the aforementioned transformation. Some preliminary catalytic tests involving the transfer hydrogenation of cyclohexanone and the hydrogenation of phenylacetylene have also been carried out.

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Synthesis and Structure of New (Polyphosphane)ruthenium Complexes with the Hemilabile Ligand 2‐(Diphenylphosphanyl)‐1‐methyl‐1H‐imidazole − An Unexpected Rearrangement of [RuCl₂(PN)(PPh₃)₂]

Cited by 16 publications

References 58 publications

Changes in Coordination of Sterically Demanding Hybrid Imidazolylphosphine Ligands on Pd(0) and Pd(II)

Changes in Coordination of Sterically Demanding Hybrid Imidazolylphosphine Ligands on Pd(0) and Pd(II)

Synthesis and structure of new palladium complexes with the ligand 2-(diphenylphosphino)-1-methylimidazole: Evidence of hemilability

Ruthenium Arene Derivatives with PN Hemilabile Ligands. P−C Cleavage and Phosphine to Phosphinite Transformation

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