Synthesis of Novel Phosphaalkene-Based Bidentate Ligands Mes*PCH(3-R-Ar) (R = Pyridyl, Carbaldimino) and Formation of Three-Membered Palladacycles Mes*(Me)P−CH(3-R-Ar)−PdCl by Carbapalladation of the PC Double Bond

Sluis, M. van der; Beverwijk, V.; Termaten, Arjan T.; Bickelhaupt, F. Matthias; Kooijman, Huub; Spek, Anthony L.

doi:10.1021/om980913q

Cited by 31 publications

(25 citation statements)

References 40 publications

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“…As shown in Scheme b, Bickelhaupt et al . reported that the cross‐coupling reaction using gem‐ dibromophosphaethene 1 was unsuccessful because the palladated intermediate easily generates the phosphanylidenecarbene (phosphaisonitrile) intermediate [Mes*P=C:], affording phosphaalkyne (phosphaethyne) 2 . Nevertheless, reaction conditions for cross‐coupling using 1 warrant investigation and one approach is to prevent the dual elimination of bromides from 1 .…”

Section: Figurementioning

confidence: 99%

Palladium-Catalyzed Arylation of a Sterically Demandinggem-Dibromophosphaethene

2016

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Dedicated to Prof. Masaaki Yoshifuji on the occasion of his 75th birthdayThe trans bromide of 2,2-dibromo-1-(2,4,6-tri-t-butylphenyl)-1phosphaethene (Mes*P=CBr 2 ; Mes* = 2,4,6-tBu 3 C 6 H 2 ) can be successfully substituted with an aryl group by using a palladium version of the Kumada-Tamao-Corriu cross-coupling process. Predominant formation of the 2-aryl-2-bromo-1-phosphaethene [(Z)-Mes*P=C(Br)Ar] required suitable conditions including optimization of the ancillary phosphine ligand, thereby retarding the dual elimination of bromides leading to phosphaalkyne (Mes*C P). The 2-aryl-2-bromo-1-phosphaethenes hold promise as versatile synthons for functional p-conjugated molecules, and stereospecific transformations of the bromine atom by halogen-metal exchange and palladium-catalyzed arylations were demonstrated.[a] Prof.

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Section: Figurementioning

confidence: 99%

Palladium-Catalyzed Arylation of a Sterically Demandinggem-Dibromophosphaethene

2016

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“…Figure 1a shows an STM image obtained for a 1 mm solution of Ir-C 18 on HOPG. The image shows several crystalline domains with dimensions of tens of nanometers.…”

Section: Resultsmentioning

confidence: 99%

“…Our attempts to obtain an STM image afforded only diffuse unclear images. We believe that this is due to a more disordered, and hence more mobile, molecular arrangement as im- On the basis of the above observations, we have concluded that the molecular arrangement in the two-dimensional domains from the optically active Ir-C 18 is different from that of racemic Ir-C 18 . This in turn leads to the conclusion that the nano-and microslips prepared from the racemic mixture of Ir-C 18 are racemates.…”

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confidence: 81%

“…The ligands with a long alkyl chain, 2-(3-alkoxyphenyl)pyridine, were obtained by alkylation of 3-iodophenol followed by the Stille coupling with 2-(tributylstannyl)pyridine. [18] Alternatively, the ligands could also be obtained by alkylation of 3-(pyridin-2-yl)phenol, [19] obtained by the Stille coupling of 3-iodophenol and 2-(tributylstannyl)pyridine. [18] The ligands thus prepared were refluxed in ethylene glycol with [IrA C H T U N G T R E N N U N G (acac) 3 ] to afford the desired Ir-C n .…”

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confidence: 99%

“…[18] Alternatively, the ligands could also be obtained by alkylation of 3-(pyridin-2-yl)phenol, [19] obtained by the Stille coupling of 3-iodophenol and 2-(tributylstannyl)pyridine. [18] The ligands thus prepared were refluxed in ethylene glycol with [IrA C H T U N G T R E N N U N G (acac) 3 ] to afford the desired Ir-C n . Optical resolution (> % 90 % ee) was achieved by chiral HPLC on a Jasco chromatograph (PU-1580) system equipped with a Chiralcel OD (Daicel) column by using hexane/2-propanol 96:4.…”

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Ordered Arrays of Organometallic Iridium Complexes with Long Alkyl Chains on Graphite

Otsuki

Tokimoto

Noda

et al. 2007

Chemistry A European J

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Iridium(III) fac-tris(2-phenylpyridine) fac-[Ir(ppy)3] complexes equipped with long alkyl chains were prepared to examine their capability to form organized arrays on the surface of highly oriented pyrolytic graphite (HOPG). The molecules form lamellar arrays at the 1-phenyloctane/HOPG interface. From the analysis of the STM images, it was concluded that the molecules align with alkyl chains being interdigitated. Similar lamellar arrays were also obtained at the air/HOPG interface upon drop-casting of toluene solutions. The lamellar structure at the molecular level leads to rectangular two-dimensional crystalline domains a few hundred nanometers long (nanoslips). Infrared external reflection spectroscopy suggested that the adsorbed alkyl chains adopt the trans-zigzag conformation in the nanoslip, although the orientations of the zigzag plane of the alkyl groups are mixed. Cyclic voltammetry indicates fast electron transfer between the adsorbed molecules and the substrate and significant intermolecular electronic interactions. It was found that annealing at high temperatures is an effective method to prepare ordered assemblies more than a few micrometer scale (microslips). The orientations of the nanoslips prepared from the racemic mixture exhibited an apparent 12-fold symmetry, while its optically active enantiomer resulted in more irregular domains with a six-fold symmetry, implying an important role of chirality on packing at the molecular level and on the orientation of the domains at larger scales. When drop-cast from more concentrated solutions than a few hundreds of micromolar, multilayers were obtained, in which the alkyl chains in the molecules are more or less perpendicular to the surface. This structure can be transformed into the nanoslips upon standing.

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Synthesis and Reactions of Palladium and Platinum Complexes Bearing Diphosphinidenecyclobutene Ligands: A Thermally Stable Catalyst for Ethylene Polymerization

et al. 2000

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Diphosphaalkenes are phosphorus analogues of diimines and form stable chelate rings with transition metal species. [1±3] The coordination structures resemble those of diimine complexes. However, owing to the unique electronic nature of PC bonds, diphosphaalkene complexes are expected to possess rather intriguing chemical properties, significantly different from the diimine analogues. Thus, we have been interested in the reaction chemistry of diphosphaalkene complexes, particularly in catalytic systems; data for such systems is extremely limited. [2] Herein we examine the synthesis, structures, and catalytic properties of some methylpalladium and platinum complexes (1 ± 4) coordinated with 3,4-bis[(2,4,6-tri-tert-butylphenyl)phosphinidene]cyclobutene derivatives. [4] A cationic monomethylpalladium complex derived from 1 exhibits good catalytic activity for ethylene polymerization. P P R R M Me Me tBu tBu tBu tBu tBu tBu 3: M = Pd, R = H 4: M = Pt, R = Ph 1: M = Pd, R = Ph 2: M = Pd, R = SiMe 3The diphosphaalkene ligands in 1 ± 4 were chosen with reference to findings reported by Brookhart et al. on nickeland palladium-based catalysts for ethylene polymerization. [5,6] There the key to high catalytic activity was the use of a-diimine ligands having bulky aryl groups at the nitrogen atoms. The diphosphinidenecyclobutene ligands possess similar structural features.Complexes 1 and 2 were prepared by ligand displacement of [PdMe 2 (tmeda)] (tmeda tetramethylethylenediamine) with phenyl-and trimethylsilyl-substituted ligands in Et 2 O and isolated as orange crystals in 94 % and 63 % yields, respectively. Complex 3 was not obtained by this method but prepared in 60 % yield by using [PdMe 2 (cod)] (cod cyclooctadiene) in place of [PdMe 2 (tmeda)]. The platinum complex 4 was synthesized from [Pt 2 Me 4 (SMe 2 ) 2 ] in 89% yield. All complexes were characterized by NMR spectroscopy and elemental analysis (see Supporting information).The X-ray structure of 4, [7] which clearly shows chelate coordination of the diphosphinidenecyclobutene ligand (Figure 1). The two aryl rings on the phosphorus atoms are almost Figure 1. Molecular structure of 4. Hydrogen atoms are omitted for clarity. Selected bond lengths [] and angles [8]: Pt-C(1) 2.093(3), Pt-P 2.

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Synthesis of Novel Phosphaalkene-Based Bidentate Ligands MesPCH(3-R-Ar) (R = Pyridyl, Carbaldimino) and Formation of Three-Membered Palladacycles Mes(Me)P−CH(3-R-Ar)−PdCl by Carbapalladation of the PC Double Bond

Cited by 31 publications

References 40 publications

Palladium-Catalyzed Arylation of a Sterically Demandinggem-Dibromophosphaethene

Palladium-Catalyzed Arylation of a Sterically Demandinggem-Dibromophosphaethene

Ordered Arrays of Organometallic Iridium Complexes with Long Alkyl Chains on Graphite

Synthesis and Reactions of Palladium and Platinum Complexes Bearing Diphosphinidenecyclobutene Ligands: A Thermally Stable Catalyst for Ethylene Polymerization

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