Nickel complexes imino

There is another structure which, although it does not represent a typical azomethine compound, is synthesized from nickel complexes of the anilide of di-imino butyric acid (35). 

Phenylmethylsilanediol, synthesis, 42 155 Phenylsilanetriol, monosodium salts, 42 169 4 -Phenyl-2,2 6, 2 -terpyridine bis nickel complex, 30 74 molecular structure, 30 74 PhjtfluorenyllSiOH, 42 197 (Ph(Me2N)C-=Nli], 37 59-65 orientation of imino ligand, 37 61-63 (PhMe SiljCSiH OH, 42 244-245, 248 (PhMe SiljCsiMeHlOH), 42 191 Phosphaalkenes acyclic, 33 338-353 butadienes, 33 346-349 cumulenes, 33 352... 

Not only palladium, but many more non-metallocene late (and early) transition metal catalysts for the coordination polymerization of ethene and 1-olefins were reported [11]. Among the most significant findings in this area are the disclosures of novel highly active and versatile catalysts based on (i) bidentate diimine [N,N] nickel and palladium complexes [12], (ii) tridentate 2,6-bis(imino)pyridyl [N,N,N] iron and cobalt complexes [13], and (iii) bidentate salicyl imine [N,O] nickel complexes [14]. 

Conjugation between the imino and acyl [121], or nitrile (in complex 1.47) [122] moieties permitted the remote activation of nickel. Another catalyst (1.48) exhibiting coordination via an alkenyl moiety is noteworthy because of its sterically small size, which should prohibit the production of high molecular weight polymers [123], This is believed to be possible because of the catalyst s unique electronic properties. As bulkier imino-aryl substituents are introduced, polymerization activity and polymer molecular weight increases, as expected [124],... 

The square-planar Ni(II) complex of an anionic macrocyclic ligand, 21, was prepared from the template reaction of 3,3 -(ethylenebis(imino-methylidene)bis(2,4-pentanedionato)nickel(II) with 1,3-diamino-2-pro-panol [Eq. (10)]. The uncoordinated -OH group reacted smoothly with acylating agents, resulting in -COPh and -COCH3 (28). 

The alkali metals Li and Na promote the dimerization of the complex N,N -o phenylenebis(salicylideneiminato)nickel(II), [Ni(salophen)], by means of the reductive coupling of two imino groups between two Ni(salophen) molecules (Scheme 29).2352... 

In contrast to nickel(II) complexes with saturated tetraaza macrocycles, which exhibit a variety of coordination numbers and geometries, the ligands being in either a planar or a folded coordination, the majority of the complexes formed by unsaturated tetraaza macrocycles are square planar. Few six-coordinate complexes have been prepared with 14- and 16-membered macrocycles. It is expected that imino groups present in the chelate rings reduce the possibility of the folded coordination of the macrocycles and the conformational possibilities of the chelate rings. 

A nickel-based catalyst system, which produces, in the absence of comonomers, highly short-chain branched polyethene was developed by Brookhart et al. [23]. Independently, the groups of Brookhart [24, 25, 26] and Gibson [27, 28, 29, 30] developed efficient iron- and cobalt-based catalyst systems. Nickel or palladium is typically sandwiched between two a-di-imine ligands, while iron and cobalt are tridentate complexed with imino and pyridyl ligands. 

Complexes of 107 have been isolated for copper(II), cobalt(II), and nickel(II) cations103). Condensation of 2,6-diaminopyridine with 108 affords the dimeric macrocycle 111 (70%). No complexes have been reported for ligands 111l08) or 113104 106>. in addition, the reaction of l,3-6is[(l-imino-4,5,6,7-tetrahydro-3-iso-indoline)amino]benzene with 2,6-diaminopyridine gives 113 (70%) 104>107>. 

Oxazolidines (53) are readily formed from aldehydes or ketones and ethanolamines they can be hydrolyzed with ease and show reactions that might be expected of the imino alcohol intermediate (54). Among these are the addition of Grignard reagentsand catalytic hydrogenolysis of the C—O Ixjnd (equation 28).This reaction is exothermic over Adam s catalyst in methanol but slower in acetic acid. Nickel and copper chromite are also effective but at higher temperatures and pressures,as is the case with palladium. The same cleavage occurs with LAH (unassisted)and with the borane-THF complex. ... 

Although the term dynamical combinatorial chemistry has only been coined at the end of the last century, the template effect has been used for a much longer time. Some of the best known macrocyclic ligands such as cyclam probably would not have been known so well if their synthesis had not implied the template effect. Probably the first example of a metal ion template for the formation of imino-macrocycles N. F. Curtis, D. A. House, Structure of some aliphatic Schiff-base complexes of nickel (II) and copper (II), Chem. and End., 1961, 42, 1708-1709. 

Britovsek et al. [38] reported a bidentate imino quinolinyl nickel dibromide complex (Fig. 3.9) for the polymerization of ethylene, but it showed moderate activity toward the formation of oligomers rather than polymers [37]. 

An a-hydrogen elimination is the microscopic reverse of hydride insertion/imino formyl formation and affords the nickel(ii) hydride complex (c. Scheme 2). Subsequent olefin insertion and isocyanide insertion gives hydrocarbation product (f. Scheme 2). Isotopic labeling experiments by using < 4-ethylene or [Ni C(D)N(D)xylyl (triphos)](CF3S03)2 showed deuterium at both the methylene group and the methyl group of the a-ethyl carbene (f. Scheme 2), not expected in an alkene pathway. 

Another example of asymmetric reduction of a polyketone was given by Schulz [185] who reported the quantitative reduction of polyvinyl-p-acetophenone by AlLiH4//-quinine complexes. The optical yield is very poor and was evaluated as 9%. Asymmetric hydro-genetion of ketone [186] or imino groups [187] was described by Plateh etal. The catalyst used was Raney nickel modified by /-glutamic or tartaric acid or by a macromolecular substrate (e.g. OA polyhydroxyesters). (More details are given by Dr Luisi in his chapter). The studied polymers were [186, 187] ... 

In contrast to the above results, the nickel isocyanide complexes react with tolane to afford diiminocyclobutenes in variable yield (Suzuki and Takizawa, 1972). These reactions presumably proceed via mixed isocyanide-acetylene complexes since these can be prepared independently and gave the same product on thermolysis. The imino compounds are readily hydrolyzed to cyclobutenediones. 

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