Tris phosphite structure

Catalyst deactivation essentially results from the formation of cyanides, such as Ni(CN) or CuCN. The role of (he phosphite ligands in Ni(0) caralysis is to prevent such inhibition pathways. Tlie phosphite structure is very critical in achieving the best catalytic activity [Ig). Tri(/J / butylphenyl)phosphiie (1) is, for example, much more active than triphenylphosphitc (2). 

The two classes of hindered substituted bis- and tris- phosphites having either (a) dibenzo[d,f][1,3,2]dioxaphosphepin or (b) dibenzo[d,g][1,2,3Jdioxaphosphocin rings were selected for study as processing stabilizers because their bicyclic structures promised stabilizers of increased thermal and hydrolytic stability compared to the acyclic hindered phenylphosphonites previously studied (1). 

Several cationic q -alkenyl-complexes obtained by protonation or deuteria-tion of tris(phosphite)iron q -diene complexes have been studied by nmr spectroscopy (Ittel et ai, 1979). The structures are octahedral, coordinated with phosphite ligands at three of the sites. The q -alkenyl group occupies two sites and a hydrogen atom which is adjacent to the alkenyl-group fills the sixth site giving a noble gas (18-electron) configuration at the iron centre. 

Cobalt complexes find various applications as additives for polymers. Thus cobalt phthalocyanine acts as a smoke retardant for styrene polymers,31 and the same effect in poly(vinyl chloride) is achieved with Co(acac)2, Co(acac)3, Co203 and CoC03.5 Co(acac)2 in presence of triphenyl phosphite or tri(4-methyl-6- f-butylphenyl) phosphite has been found to act as an antioxidant for polyenes.29 Both cobalt acetate and cobalt naphthenate stabilize polyesters against degradation,73 and the cobalt complex of the benzoic acid derivative (12) (see Section 66.4) acts as an antioxidant for butadiene polymers.46 Stabilization of poly(vinyl chloride)-polybutadiene rubber blends against UV light is provided by cobalt dicyclohexyldithiophosphinate (19).74 Here again, the precise structure does not appear to be known. 

Tetracarbonyl cations [Cr(CO)4(L2)]+, where L2 represents arylphosphines, alkyl, or aryl phosphites, or a bidentate ligand with phosphorus or arsenic donor atoms, have been produced by both chemical and electrochemical means. However, oifly one of these complexes, namely, tra i -[Cr(CO)4(PPh3)2]+, is stable enough to be isolated as the perchlorate salt. Exposure to light and moisture produces tra i -Cr(CO)4(PPh3)2 via disproportionation. Just as easily isolated, but somewhat less sensitive, are the [Cr(CO)3(PR3)3]+ cations. " Oxidation with a silver ion or NO+ converts the /uc-(R3 = Me2Ph, (OMe)3) and mer-(R3 = (OMe)3, (OMe)2Ph, (OPh)3) complexes into Cr products with mer structures. Light and heat promote the formation of reduced wer-Cr(CO)3 (PR3)3. These tetra(carbonyl) and tri(carbonyl) cations have been the subject of ESR spectroscopy and theoretical study. 

Some complexes dissociate fully in solution (e.g., 7r-allyl nickel tri-fluoroacetate) whence [63] Rp cc [C2][M]. Donor solvents (triphenyl-phosphite, nitrobenzene) can also coordinate with the metal and influence catalyst dissociation with effects on rate and polymer molecular weight the structure of the polymer may also be affected [173]. 

As in past years, there have been reports of the reactions of quinones with phosphites. It has been supposed that these reactions initially involve transfer of an electron from the phosphite to the quinone. Support for this postulate has come from the observation of the formation of paramagnetic species in the reactions by e.s.r. spectroscopy. A quantitative study has now shown that the rate of the electron process correlates with the reduction potential of the quinone. The actual structures of the radicals produced in some of these reactions have also been elucidated. For example, triethyl phosphite reacts with 2,7-dinitrophenanthraquinone to give the quinone radical ion and ethyl radicals. Tris(dimethylamino)phosphine reacts with phenanthraquinone to give the radical cation (56). This was identified by use of... 

The new trinorborn-l-yl phosphite (7) has been prepared and shown to give quasi-phosphonium salts which are even more stable than those derived from trineopentyl phosphite thus the salt with methyl iodide had a half-life of more than 100 h in deuterochloroform at 150 C, compared to less than 2 h at 33 C for the neopentyl analogue. Although phenacyl chloride gave mainly the Arbuzov intermediate (8), with p-nitrophenacyl chloride a stable Perkow intermediate (9) could be isolated and its X-ray crystal structure studied. Trifluoroiodomethane with tris(dialkylamino)phosphines gave the normal trifluoromethylphosphonium salts (10) in the absence... 

The reaction of calix[4]arene or its p-t-butyl derivative with tris(dimethylamino)phosphine gives the basket zwitterionic six-coordinate phosphorus derivatives (177 R = H, Bu ) <90JA9422, 91CC562, 93PS(75)253, 94IC2657). The attempted deprotonation at phosphorus with -butyllithium to give the basket aminophosphorane with four basal P—O bonds was unsuccessful (the NH proton was removed), but trifluoroacetic acid or heat yielded the bicyclic phosphite (178 R = H, Bu ). The crystal structures of (177 R = H) and the oxidized form of (178 R = H) were determined. The P—H atom in (177 R = Bu ) is inside the basket. 

As listed in Table 3.24, organic phosphorous compounds such as tris(2,4-di-ieri-butyl-phenyl)phosphite [165] and tris(tribromoneopentyl) phosphate [166] have been attempted. A new class of iV-alkoxy hindered amines (NOR HAS) have been pursued by Ciba as fire retardants [167]. An example of these compounds is Flamstab NOR TM 116, the structure of which is shown below. It is a reaction product of A,A -ethane -l,2-diyl6z5(l,3-propanediamine),... 

FIGURE 1 The molecular structure of Irgafos 168 [tris (2, 4-di-tert-butylphenyl) phosphite], (Schwetlick 1990)... 

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