Phosphines organometallic

The Karplus angle relationship works quite well for organometallic phosphine complexes. For example in the compound [IrlPMeslsHCllCsHsN)], the /( P, H) is 153.5 Hz for the PMes trans to the hydride, but only 19.8 Hz to the (chemically equivalent) cis phosphines. 

Compounds Carbonyls, nitrosyls, organometallics phosphine complexes Halides, oxides, aquo complexes alkoxides, ammines. 

Transition-metal organometallic catalysts in solution are more effective for hydrogenation than are metals such as platinum. They are used for reactions of carbon monoxide with olefins (hydroformyla-tion) and for some ohgomerizations. They are sometimes immobihzed on polymer supports with phosphine groups. 

Low surface energy substrates, such as polyethylene or polypropylene, are generally difficult to bond with adhesives. However, cyanoacrylate-based adhesives can be effectively utilized to bond polyolefins with the use of the proper primer/activa-tor on the surface. Primer materials include tertiary aliphatic and aromatic amines, trialkyl ammonium carboxylate salts, tetraalkyl ammonium salts, phosphines, and organometallic compounds, which are initiators for alkyl cyanoacrylate polymerization [33-36]. The primer is applied as a dilute solution to the polyolefin surface, solvent is allowed to evaporate, and the specimens are assembled with a small amount of the adhesive. With the use of primers, adhesive strength can be so strong that substrate failure occurs during the course of the shear tests, as shown in Fig. 11. 

With rare exceptions, such as [Fe(bipy)3]°, oxidation states lower than +2 are represented only by carbonyls, phosphines, and their derivatives. These will be considered together with other organometallic compounds in Section 25.3.6. 

Besides [Ni(CO)4] and organometallic compounds discussed in the next section, nickel is found in the formally zero oxidation state with ligands such as CN and phosphines. Reduction of K2[Ni (CN)4] with potassium in liquid ammonia precipitates yellow K4[Ni (CN)4], which is sensitive to aerial oxidation. Being... 

Indeed, these reactions proceed at 25 °C in ethanol-aqueous media in the absence of transition metal catalysts. The ease with which P-H bonds in primary phosphines can be converted to P-C bonds, as shown in Schemes 9 and 10, demonstrates the importance of primary phosphines in the design and development of novel organophosphorus compounds. In particular, functionalized hydroxymethyl phosphines have become ubiquitous in the development of water-soluble transition metal/organometallic compounds for potential applications in biphasic aqueous-organic catalysis and also in transition metal based pharmaceutical development [53-62]. Extensive investigations on the coordination chemistry of hydroxymethyl phosphines have demonstrated unique stereospe-cific and kinetic propensity of this class of water-soluble phosphines [53-62]. Representative examples outlined in Fig. 4, depict bidentate and multidentate coordination modes and the unique kinetic propensity to stabilize various oxidation states of metal centers, such as Re( V), Rh(III), Pt(II) and Au(I), in aqueous media [53 - 62]. Therefore, the importance of functionalized primary phosphines in the development of multidentate water-soluble phosphines cannot be overemphasized. 

Various phosphines are valuable ligands for metal centers involved in catalytic and noncatalytic organometallic chemistry. Unfortunately, phosphines are readily oxidized to phosphine oxides and to prevent their oxidation they... 

A. From Halogenophosphine and Organometallic Reagent.—Mesityl-magnesium bromide reacts with chlorodiethylphosphine and dichloroethyl-phosphine at — 10 °C in THF to yield mesityldiethylphosphine and dimesitylethylphosphine respectively. ... 

The catalysts used in hydroformylation are typically organometallic complexes. Cobalt-based catalysts dominated hydroformylation until 1970s thereafter rhodium-based catalysts were commerciahzed. Synthesized aldehydes are typical intermediates for chemical industry [5]. A typical hydroformylation catalyst is modified with a ligand, e.g., tiiphenylphoshine. In recent years, a lot of effort has been put on the ligand chemistry in order to find new ligands for tailored processes [7-9]. In the present study, phosphine-based rhodium catalysts were used for hydroformylation of 1-butene. Despite intensive research on hydroformylation in the last 50 years, both the reaction mechanisms and kinetics are not in the most cases clear. Both associative and dissociative mechanisms have been proposed [5-6]. The discrepancies in mechanistic speculations have also led to a variety of rate equations for hydroformylation processes. 

Second, as a logical development of the first approach, polyphosphazenes have been synthesized that bear phosphine units connected to aryloxy side groups (37). The phosphine units bind organometallic compounds, such as those of iron, cobalt, osmium, or ruthenium (38). In several cases, the catalytic activity of the metal is retained in the macromolecular system (39). A similar binding of transition metals has been accomplished through nido carboranyl units linked to a polyphosphazene chain (40). 

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