Acrylonitrile complexes

In addition to OH , other nucleophiles such as BH4 ,318 CN-319,320 and N3-321 also add at the nitrile carbon of cobalt(III)-nitrile complexes at rates which are = 104 times those of the corresponding reactions of the free ligands. Catalysis by C032 in the hydration of [(NH3)5RuNCMe]3+,316 and of the acrylonitrile complex [(NH3)5CoNCCH=CH2]3+,322 has been observed. In the latter complex, a direct nucleophilic pathway results in the incorporation of oxygen from C032 into the amide product with elimination of C02. 

Spontaneous homopolymerization of the (isoprene-complexed acrylonitrile) complex ... 

As previously discussed, the copolymers produced in the zinc chloride-free radical system are not necessarily random copolymers but are probably the result of the copolymerization of the acrylonitrile-complexed acrylonitrile complex with the olefin-complexed acrylonitrile complex. Further, the olefin-alkylaluminum halide complexed acrylonitrile complex only differs from the olefin—zinc chloride complexed acrylonitrile complex in degree rather than in kind—i.e., the former is an unstable charge transfer complex capable of spontaneous uncoupling of the diradical system followed by intermolecular diradical coupling, while the latter is a stable charge transfer complex requiring radical attack to uncouple the diradical system. 

As shown in Figure 1, the-yield of copolymer is extremely temperature dependent, indicating that either the acrylonitrile-ethylaluminum dichloride complex is unstable or the propylene-ethylaluminum dichloride complexed acrylonitrile complex is not formed as the temperature is increased. 

Acrylonitrile and related compounds displace all the carbonyl groups from nickel carbonyl to form [(RCH CHCN)2Ni], in which the nitrile bonds through the olefinic double bond 222, 418). The bis(acrylonitrile) complex catalyzes many reactions, including the conversion of acrylonitrile and acetylene to heptatrienenitrile and the polymerization of acetylene to cyclooctatetraene 418). Cobalt carbonyl gave a brown-red amorphous material with acrylonitrile, which had i cn absorptions typical of uncoordinated nitrile groups, but interestingly, the presence of C=N groups was also indicated 419). In acidic methanol, cobalt carbonyl converts a,j8-unsaturated nitriles to saturated aldehydes 459). 

Most remarkably, no codimerization involving the unsaturated ester molecule is observed, even though nickel compounds such as the acrylonitrile complex are efficient catalysts for such codimerization reactions vide infra). An additional homodimer, l,3-bis(methylene)cy-clohexane (6), is formed as a minor product with phosphane-modified nickel catalysts. Only trace amounts of product 6 are obtained with maleic anhydride as cocatalyst. 

A correlation of a high thermal stability with a high ionization potential for a olefin has been observed with iron (O)-olefin complexes of the type Fe(CO)4-(olefin) 96> i.e. poor donor but good acceptor properties increase the stability of the complex. The acrylonitrile complex is one of the most stable, the ethylene complex the least stable and the complexes of styrene or vinyl chloride are of intermediate stability. 

More recently, Dimonie and Negulescu reported that the use of the BF3-acrylonitrile complex instead of BF3 OEt2 as initiator but otherwise under identical conditions eliminates the induction period in the polymerization of TXN in benzene solvent at 35 °C 95>. The proposed interpretation may require confirmation. 

A range of related acrylonitrile complexes (28) (R = H, Me, MeO R = H, Me R = OMe, OEt) have been prepared for the first time, and the regiospecificity of addition by carbon and heteroatomic nucleophiles examined. ... 

This also applies to the polymerization of MX, with unsaturated nitriles, although homopolymerization of acrylonitrile complexes with Zn(II) halides (in... 

In the reaction of aromatic aldehydes with acrylonitrile, complexes 105 containing two molecules of MBH adduct and one molecule of DABCO... 

Whatever the cause for deviation of sequence distribution in SAN, there has been considerable interest in the development of polymerization methods to minimize the AN sequence length [6,7,58,68-75]. Many researchers [6,7,71-73,75,76] have shown that the addition erf Lewis acids to SAN copolymerization has a strong influence upon sequence distribution. Electron poor Lewis adds ormplex with the electron rich nitrile group of acrylonitrile. Complexation of the nitrile group increases its inductive effect resulting in a decrease of electron density of the acrylonitrile double bond (its Alfrey-Price e-value becomes more positive). Thus oopolymerization of the acrylonitrile ... 

The presence of the electron-withdrawing nitrile group in acrylonitrile leads to polarization (6+CH2=CH-C=N6-) that promotes nucleophilic attack at the methylene carbon atom. The coordination of acrylonitrile to a metal center through the nitrile group results in enhanced polarization and further promotes reactions with nucleophilic reagents. For example, acetylacetonate ion reacts with the acrylonitrile complex, [Co(NH3)5NsCCH=CH2] , in aqueous solution at pH = 9, Eq. 1.28 62... 

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