Diphosphines reactions with

The alkah metal phosphides of formula M P and the alkaline-earth phosphides of formula M2P2 contain the P anion. Calcium diphosphide [81103-86-8] CaP2, contains P reaction with water Hberates diphosphine and maintains the P—P linkage. 

The borane group of MiniPHOS was removed using the same protocol (Scheme 21). In contrast, however, reaction of free diphosphines 13 with [Rh(nbd)2]+X (X=Bp4, PFg) afforded in all cases, and independently of the reaction conditions, bischelate complexes 106. James and Mahajan demonstrated... 

The proposed reaction mechanism involves intermolecular nucleophilic addition of the amido ligand to the olefin to produce a zwitterionic intermediate, followed by proton transfer to form a new copper amido complex. Reaction with additional amine (presnmably via coordination to Cn) yields the hydroamination prodnct and regenerates the original copper catalyst (Scheme 2.15). In addition to the NHC complexes 94 and 95, copper amido complexes with the chelating diphosphine l,2-bis-(di-tert-bntylphosphino)-ethane also catalyse the reaction [81, 82]. 

A P NMR study of stoichiometric reactions using the di-primary phosphine H2PCH2CH2CH2PH2 provided more information on the reaction mechanism (Scheme 5-12, Eq. 2). Norbornene was displaced from Pt(diphosphine)(norbornene) by ethyl acrylate. Reaction with the diphosphinopropane was very fast this gave the hydrophosphination product, which, remarkably, did not bind Pt to give Pt(diphos-phine), instead, Pt(diphosphine)(norbornene) was observed [12]. 

Scheme 1.62 Test reaction with 2,2 -biphosphole-derived diphosphine sulfide.

Scheme 5.11 Pd- and Pt-catalysed Diels-Alder reactions with C2-symmetric biheteroaromatic diphosphines.

Complexes [Ni(H)(diphosphine)2]+ can be prepared by two ways, either by reaction of [Ni11 (diphosphine)2]2+ with H2 in the presence of base, or by reaction of [Ni°(diphosphine)2] with NH4+. A linear free energy relationship exists between the half-wave potentials of the Ni /Ni" couples of different [Ni(diphosphine)2] complexes and the hydride donor ability of the corresponding [Ni(H)(diphosphine)2]+.2320 Several methods have been used to determine those hydride... 

The ionic P-P bond polarization renders P-phosphino-NHPs highly active reactants for various metathesis and addition reactions at exceedingly mild conditions. Metathesis is observed in reactions with alcohols, chloroalkanes, and complex transition metal halides (Schemes 11 and 12) [39, 73], Of particular interest are the reactions with chlorotrimethylstannane which yield equilibria that are driven by a subtle balance of P-X bond strengths to yield either diphosphines or P-chloro-NHPs as preferred product (Scheme 11). Chlorotrimethylsilane does not react with... 

The metal and ammonium salts of dithiophosphinic acids tend to exhibit far greater stability with respect to this thermal decomposition reaction, and consequently these acids are often prepared directly in their salt form for convenience and ease of handling. Alkali-metal dithiophosphinates are accessible from the reaction of diphosphine disulfides with alkali-metal sulfides (Equation 22) or from the reaction of alkali-metal diorganophosphides with two equivalents of elemental sulfur (Equation 23). Alternatively, they can be prepared directly from the parent dithiophosphinic acid on treatment with an alkali-metal hydroxide or alkali-metal organo reagent. Reaction of secondary phosphines with elemental sulfur in dilute ammonia solution gives the dithiophosphinic acid ammonium salts (Equation 24). 

In sharp contrast to the intensely studied reactions of dipenteles with transition metal compounds, reactions with group 13 metal compounds are almost unknown. Only two diphosphine-borane bisadducts of Type C ([H3B]2[Me4P2], [H2(Br)B]2[Me4P2]) have been synthesized and structurally characterized65 but no diarsine, distibine or dibismuthine adducts. We, therefore, became interested in the synthesis of such compounds, focusing... 

Until now, only a few effective ligands of this type have been identified (Fig. 25.4). Kagan and co-workers [5] prepared one of the few chiral diphosphines with only planar chirality and obtained 95% ee for the hydrogenation of DM IT with LI (Table 25.1, entry 1.1.), but enantioselectivities for several enamide derivatives were below 82% ee (the best results were with the cyclohexyl analogue of LI). For the reactions with DM IT or MAC, the cationic Rh-kephos complex showed comparable or better performance than corresponding duphos catalysts. 

When an appropriate chiral phosphine ligand and proper reaction conditions are chosen, high enantioselectivity is achievable. If a diphosphine ligand with C2 symmetry is used, two diastereomers for the enamide-coordinated complex can be formed because the olefin can interact with the metal from either the Re- or Sf-face. Therefore, enantioselectivity is determined by the relative concentrations and reactivities of the diastereomeric substrate-Rh complexes. It should be mentioned that in most cases it is not the preferred mode of initial binding of the prochiral olefinic substrate to the catalyst that dictates the final stereoselectivity of these catalyst systems. The determining factor is the differ-... 

From MetallatedPhosphines. The synthesis of polymeric tertiary phosphines based on the reaction of lithium diphenylphosphide with chloromethylated polystyrenes continues to attract interest.9 10 Considerable breakdown of the carbon-carbon back-bone of PVC occurs on reaction with lithium diphenylphosphide in THF, and only oligomers of low molecular weight result.11 The potassium salt (9) reacts with chloromethylated polystyrene to form the polymeric diphosphine (10).12... 

The diphosphines (102) undergo ready degradation to give derivatives of (103) on reaction with oxygen, methyl iodide, bromine, or acetic acid a mechanistic scheme has been suggested.104... 

The formation of ester via reaction (11) of Figure 12.10 deserves some further attention as it is not one of the elementary steps discussed in Chapter 2. One possible mechanism is the direct, outer-sphere attack of an alcohol or alkoxide at the acyl carbon atom, similar to the reaction of acid halides and alcohols (17-18 in Figure 12.13). This reaction is accessible for both cis and trans diphosphine complexes 12 and 13. Since monophosphines give mainly trans acyl complexes 13, not suited for insertion reactions, they were thought to have a preference for making esters or low molecular weight products. Trans complexes do form esters in reactions with alcohols or alkoxides, but this does not give direct information about the mechanism [42,43,44],... 

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