Phosphines aminophosphine complexes

Pt(II) complexes generally give hydroformylation products with higher asymmetric induction than Rh(I) complexes. A Pt(II)-SnCl2 complex with a chiral phosphine, aminophosphine, or phosphinite also catalyzes the hydroformylation of styrene in up to 86% optical yield (115). Stille noticed that the PtCl2(bppm)-SnCl2 combined catalyst is... 

The bidentate phosphine dppe (l,2-bis(diphenylphosphino)ethane) and the aminophosphine eddp (2-aminoethyl-diphenylphosphine) form mixed ligand (N, P, O) complexes such as Co(acac) (edpp)2 and Co(acac)(en)(dppe). A preference for trans N-Co-P and P-Co-P configurations over N-Co-N was found for the bis(edpp) complexes.925... 

Pure phosphine-metal atom studies with the early transition metals have been lacking. The only complex prepared this way prior to 1978 was Cr(Pp3)6. King and Chang, with the unique aminophosphine systems Me2NPF2 and MeN(Pp2)2, have generated a variety of new homoleptic M-(L) systems (see Homoleptic Compound). The codeposition of Cr vapor with these ligands yields the complexes shown ... 

Of the aminophosphines, tris(dimethylamino)phosphine is the most widely used. It has the feature of combining three hard nitrogen and the soft phosphorus sites, thus being potentially an eight-electron donor hgand. In complexes such as [M(CO)5P(NMe2)3], it is a two-electron P-donor ligand. ... 

Aminophosphines. - The bis(V-pyrrolidinyl)phosphines (139), prepared conventionally by treatment of the appropriate organodichlorophosphine with an excess of pyrrolidine, have proved to be unusually electron-rich <7-donor ligands when compared to either tris(V-pyrrolidinyl)phosphine, or trialkyl-and triaryl-phosphines. Full details of a route to the polycylic aminophos-phirane systems (140) have now appeared. The bis(aminophosphine) (141) has been prepared and used in the synthesis of macrocyclic metal complexes. Two new chiral aminophosphine systems (142) and (143) have been prepared by transamidation of related aryl bis(dimethylamino)phosphines with a chiral amine. The chiral aminophosphine (144) has been obtained from the reaction of chlorodiphenylphosphine with the methyl ester of alanine. A range of ether-functionalised aminophosphines (145) has also been prepared. 

A variety of other nucleophiles have been used for the metal-catalyzed displacement of chlorine in nonactivated chloroarenes, including arylthiolate [191-193] and iodide [194, 195] anions, primary and secondary amines [196, 197], tertiary phosphines [198,199], and aminophosphines [200]. All these reactions are catalyzed by either preformed or generated in situ Ni(0) complexes. Very recently, however, Reddy and Tanaka [201] and Koie et al. [202] reported the arylation of secondary amines with chlorobenzene and other chloroarenes, catalyzed by palladium complexes containing bulky, electron-rich phosphines,... 

Since Wymore and Bailar (1) first prepared trans-[CoX2 l,2-bis (diethylphosphino)ethane ]X (X = Cl-, Br , and I-) in I960, many cobalt(III)-phosphine complexes have been reported (2). However, no optically active cobalt(III)-phosphine complex has ever been prepared. This paper deals with the preparation, characterization and circular dichroism (CD) spectra of octahedral cobalt(III) complexes containing aminophosphines of the type,... 

Similarly, there are examples of rhodium(I) and iridium(I) tertiary phosphine complexes that form isolable dihydrides, which with separate treatment with external base yield monohydrides, equation (k) . Hydrogenations catalyzed by rran5-RhCl(CO)(PPh3)2 " may involve rrani-RhH(CO)(PPh3)2 formed according to equation (1) via an undetected dihydride intermediate. In some aminophosphine analogues, a coordinated N atom may act as proton acceptor s. 

Mechanistic Studies. - The mechanism of the reaction of tetra-zole-activated phosphoramidites with alcohols has been studied. A series of diethyl azolyl phosphoramidites (85) was prepared from diethyl phosphorochloridite and fully characterized, and the same compounds shown to be formed from the phosphoramidite (86) and azole. The degree of formation of (85) from (86) increases with the acidity of the azole, and the proposed mechanism is a fast protonation of (86), followed by a slow, reversible formation of (85) and a fast reaction of (85) with alcohols. Another study was concerned with the influence of amine hydrochlorides on the rate of methanolysis of the phosphoramidites (87) or (88), or tris(diethylamino)phosphine.The chloride content was measured to be 10-20 mM in doubly distilled samples which explains that "uncatalysed alcoholysis is possible. Intensive purification, including treatment with butyllithium and distillation from sodium, brought the chloride content down to 0.1-1 mM. The methanolysis reaction, in methanol as the solvent, was found to be first-order in catalyst concentration. An aJb initio calculation on N- and P-protonated aminophosphine (89) gave similar proton affinities for N and P this contrasts with earlier MNDO calculations which had ff-protonated species as the most stable. The M-protonated compound had an electronic structure reminiscent of a phosphenium ion-ammonia complex. 

Other similar phosphorus ligands on solid supports and screened them in the Heck reaction.Starting from supported amino alcohols, representative members of five different families of phosphine and phosphinite ligands were synthesised /3-aminophosphines 73, A, /3-diphosphinoamines 74, a,/3-diphosphinoamines 75, /3-aminophosphi-nites 76, and A -phosphino-/3-aminophosphinites 77. Following their complexation with Pd(OAc)2, the ligands were screened in the Heck reaction and led to the identification of two lead ligands for future studies. 

A great number of aminophosphines were known prior to 1970 and were listed by Kosolapoff and Maier". Derivatives with no substituents on the nitrogen atom are stable only when the phosphorus substituents are very bulky or highly electronegative, e.g. the amino-rer -butylphosphines 24 and 25 and the amino(trifluoromethyl)phosphines 26 and 27. Derivatives with one N—H bond are more common, although eliminations (equation 34) or further reactions (equation 35) may complicate their preparation. A few aminophosphines which contain a P—H bond are known, e.g. 28, 29 and 30 they are prepared by complex hydride reduction of the corresponding aminochlorophosphines. 

Displacements. Nickel complexes can serve as an alternative to the Pd catalysts, e.g., in the synthesis of allylamines and a-allylmalonic esters. A report on the latter reaction states that bis(aminophosphine) ligands are more efficient than dppb and other usual phosphines. 

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