Nickel macrocyclic complexes synthesis

Taraszewska, J., G. Roslonek, Y.D. Lampeka, and I.M. Maloshtan (1998). Oxalate-bridged dinuclear nickel azacyclam macrocyclic complexes Synthesis and electrochemical study. J. Electroanal. Chem. 452(1), 49-56. 

Nickel-allyl complexes prepared from Ni(CO)4 and allyl bromides are useful for the ole-fination of alkyl bromides and iodides (E.J. Corey, 1967 B A.P. Kozikowski, 1976). The reaction has also been extended to the synthesis of macrocycles (E.J. Corey, 1967 C, 1972A). 

Neutral nickel(II) complexes with a number of deprotonated porphyrins have been prepared in most cases by the direct reaction of a nickel salt, usually Ni(ac)2-4H20, with the preformed diacid macrocycle, using media such as DMF, MeC02H or PhCl at refluxing temperature. Recently, the template synthesis of the complex with tetraalkylporphyrins has been reported (Scheme 61).2883 On the other hand the condensation reaction of 1,3,4,7-tetraalkylisoindole and nickel acetate tetrahydrate gives the [Ni(omtbp)] complex (omtbp = octamethyltetrabenzoporphyrinate dianion), 2884... 

Template reactions between malonaldehydes and diamines in the presence of copper(II), nickel(II) or cobalt(II) salts yield neutral macrocyclic complexes (equation 15).99-102 Both aliphatic102 and aromatic101 diamines can be used. In certain cases, non-macrocyclic intermediates can be isolated and subsequently converted into unsymmetrical macrocyclic complexes by reaction with a different diamine (Scheme ll).101 These methods are more versatile and more convenient than an earlier template reaction in which propynal replaces the malonaldehyde (equation 16).103 This latter method can also be used for the non-template synthesis of the macrocyclic ligand in relatively poor yield. A further variation on this reaction type allows the use of an enol ether (vinylogous ester), which provides more flexibility with respect to substituents (equation 17).104 The approach illustrated in equation (15), and Scheme 11 can be extended to include reactions of (3-diketones. The benzodiazepines, which result from reaction between 1,2-diaminobenzenes and (3-diketones, can also serve as precursors in the metal template reaction (Scheme 12).101 105 106 The macrocyclic complex product (46) in this sequence, being unsubstituted on the meso carbon atom, has been shown to undergo an electrochemical oxidative dimerization (equation 18).107... 

The analogy between imines and carbonyls was introduced earlier, and just as 1,3-dike-tonate complexes undergo electrophilic substitution reactions at the 2-position, so do their nitrogen analogues. Reactions of this type are commonly observed in macrocyclic ligands, and many examples are known. Electrophilic reactions ranging from nitration and Friedel-Crafts acylation to Michael addition have been described. Reactions of 1,3-diimi-nes and of 3-iminoketones are well known. The reactions are useful for the synthesis of derivatised macrocyclic complexes, as in the preparation of the nickel(n) complex of a nitro-substituted ligand depicted in Fig. 5-12. 

Transamination reactions of this type have found some synthetic application. The synthesis of the nickel(n) complex of a macrocycle indicated in Fig. 5-58 clearly involves... 

As mentioned above, reactions of this type have been widely used in the synthesis of macrocyclic ligands. Indeed, some of the earliest examples of templated ligand synthesis involve thiolate alkylations. Many of the most important uses of metal thiolate complexes in these syntheses utilise the reduced nucleophilicity of a co-ordinated thiolate ligand. The lower reactivity results in increased selectivity and more controllable reactions. This is exemplified in the formation of an A -donor ligand by the condensation of biacetyl with the nickel(n) complex of 2-aminoethanethiol (Fig. 5-78). The electrophilic carbonyl reacts specifically with the co-ordinated amine, to give a complex of a new diimine ligand. The beauty of this reaction is that the free ligand cannot be prepared in a metal-free reac-... 

In many cases it is possible to utilise the hole size effects for the synthesis of specific types of macrocycle. Thus, a tetradentate macrocycle (6.33) is expected to be obtained from a template condensation of 2,6-diacetylpyridine with 1,5,9-triazanonane in the presence of small, first-row transition metal dications. The hole size of 6.33 closely matches the size of these metal ions. This is indeed what happens when Ni2+ (r = 0.8 A) is used as a template for the condensation and the nickel(n) complex of 6.33 is obtained in good yield (Fig. 6-32). However, when Ag+ (r = 1.0 A) is used as a template, the metal ion... 

In some of the earliest experiments involving in situ macrocyclic ligand synthesis, it was shown that the reaction of 2,6-diacetylpyridine with certain polyamines in the presence of metal ions leads to the preparation of new macrocyclic complexes. As is often the case with Schiff-base condensations of the type, the addition of a small amount of acid catalyzes the reaction. Thus treatment of 2,6-diacetylpyridine with 3,3 -diaminodipropylamine [A-(3-aminopropyl)-l,3-pro-panediamine] in the presence of nickel(II) leads to the isolation of nickel complexes of the macrocyclic ligand (Me2-Pyo[14] trieneN4). " ... 

The starting material for both of these target molecules is the neutral nickel(II) complex [3,11-diacetyl-4,10-dimethyl-1,5,9,13-tetraazacyclohexa-deca-1, 3, 9, ll-tetraenato(2 —)-K N ]nickel(II), ([Ni(Ac2Me2[16]-tetra-enatoN )]). This complex is prepared by the procedure described earlier. The lacunar cyclidene ligands are constructed on the nickel(II) ion, and the formation of the second macrocyclic ring is a template reaction. The first two reactions in the Scheme are required unless R is to be methyl. Thus, the synthesis of the cobalt complex does not require these steps, whereas... 

We have reported the synthesis of functionalized calixarene 60. The crystal structure of the nickel azide complex of this dinuclear host indicates two nickel ions bound (one centered in each of the appended lower rim macrocycles), with three unique azide 1,1 end on bridging ligands cascaded in between (Fig. 6) (152). 

Camacho, D.H., Salo, E.V., Guan, Z.B., andZiUer, J.W. (2005) Nickel(ll) andpaUadium(ll) complexes with an aUcane-bridged macrocyclic ligand Synthesis, characterization, and polymerization tests. Organometallics, 24,4933—4939. 

Tetraaza macrocycles nickel complexes, 5, 5 synthesis, 2, 903 Tetraazaporphyrin, octaphenyl-metallation, 2, 858 Tetraazaporphyrins synthesis, 2, 857... 

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