Nickel template synthesis

A recent example, with references to previous literature, is in nickel(II) template synthesis of macrotricyclic complexes from formaldehyde and triamines, M. P. Suh, W. Shin, S.-G. Kang, M. S. Lah and T.-M. Chung, Inorg. Chem. 28, 1602 (1989). 

Various metal and metal oxide nanoparticles have been prepared on polymer (sacrificial) templates, with the polymers subsequently removed. Synthesis of nanoparticles inside mesoporus materials such as MCM-41 is an illustrative template synthesis route. In this method, ions adsorbed into the pores can subsequently be oxidized or reduced to nanoparticulate materials (oxides or metals). Such composite materials are particularly attractive as supported catalysts. A classical example of the technique is deposition of 10 nm particles of NiO inside the pore structure of MCM-41 by impregnating the mesoporus material with an aqueous solution of nickel citrate followed by calicination of the composite at 450°C in air [68]. Successful synthesis of nanosized perovskites (ABO3) and spinels (AB2O4), such as LaMnOs and CuMn204, of high surface area have been demonstrated using a porous silica template [69]. 

The template synthesis has also been successfully employed for the preparation of macrocycles containing mixed donor atoms. Examples which refer to tetra- and bexa-dentate ligands are given in Schemes 42, 47 and 50.2649,2653 2654,2658 Apart from the template synthesis a number of nickel macrocycles have been prepared by direct combination of the appropriate nickel(II) salt with the preformed macrocyclic ligand in alcoholic medium, often MeOH (see also Tables 103, 106-108). 

NiXL]X N2S2X 2.80-3.01 Template synthesis nickel complex with Five-coordinate 2813... 

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... 

Nickel(II) complexes have also been reported with reduced porphyrins, usually referred to as chlorins and corrins. Some nickel(II) complexes with chlorins (406)2883 have been obtained as by-products in the template synthesis of tetraalkylporphyrins. The main difference between [Ni(tmc)] and [Ni(tmp)] (tmc = deprotonated tetramethylchlorin, tmp = deprotonated tetra-methylporphyrin Table 110) is the lack of symmetry in the former complex with respect to the latter. The synthesis and reactivity properties of a number of corrin-nickel(II) complexes have been reported, mostly by Johnson and co-workers.2910-2915 Scheme 62 is a typical example of oxidative cyclization in the presence of a nickel salt.2914... 

In this context it is interesting to note that benzonitrile, Ph—C=N, trimerizes to a triazine on a Raney nickel surface. It was assumed that Jt-bonded nitriles were involved in the reaction mechanism.10 This reaction resembles the well-known template synthesis of phthalocyanine complexes from phthalodinitrile. Formation of linear polymers [—C(R)—N—] occurs on heating aryl or alkyl cyanides with metal halides.11... 

Template syntheses of P macrocycles are a new area. In fact, a 1978 review93 of template synthesis made no mention of P macrocycles. Template syntheses have been developed by Stelzer and co-workers.94 Firstly, two molecules of the bidentate secondary phosphine are complexed with a nickel(II) or palladium(II) salt (Scheme 6) and the resultant secondary phosphine complex is then condensed with a diketone to form the macrocyclic metal complex. Unfortunately, these macrocycles are strong field ligands and no method has yet been devised to remove the metal from the ring. On the other hand, Cooper and co-workers95 have used a template synthesis to produce a [l4]aneP2N2 macrocycle (Scheme 7). 

Simple macrocyclic quadridentate complexes can be synthesized by template reactions from ethers derived from salicylaldehyde and diamines in the presence of appropriate metal ions such as nickel(II) (equation 3).35>36 However, these reactions can also be carried out quite effectively in the absence of metal ions to yield the free ligands, which can be obtained by hydrolysis of the complexes. An iron(II) macrocyclic quinquedentate chelate of this type has been produced by template synthesis (equation 4).37... 

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... 

C.4. TEMPLATE SYNTHESIS AND MAGNETIC MANIPULATION OF NICKEL NANOWIRES... 

C.4. Template Synthesis and Magnetic Manipulation of Nickel Nanowires... 

The template synthesis of the nickel sepulchrate proved to be rather complicated because of macrocyclic and acyclic amines (Scheme 69), competitive formation reactions occurred upon refluxing ethylenediamine, formaldehyde, and ammonia in the presence of Ni + ion. 

As mentioned above, a template synthesis is a very efficient approach to the preparation of sarcophaginates and sepulchrates of certain metals. For all other metal ions, this synthetic pathway is inapplicable or gives the desired products in low yields. For instance, the yields of nickel(II) and chromium(III) sepulchrates resulting from template condensation are only ca 1 and 10%, respectively. This problem can largely be overcome if the synthesis of a variety of metal... 

The metal-ion-templated synthesis of a peraza macrocycle was reported more than 30 years ago. The macrocycle resulted from the reaction of tris(l,2-diaminoethane)nickel(ll) perchlorate with acetone to form a 14-membered macrocyclic ligand-Ni(ll) complex (5) (Curtis, 1960 Curtis and House, 1961). Numerous examples of this and other metal-ion-templated reactions have been investigated in the intervening years (Black and Hartshorn, 1972-1973 Busch, 1964 Curtis, 1968). Slightly earlier, the methyl-substituted peroxa-... 

Another celebrated example of the template effect is the synthesis of crown ethers by Pedersen [11], but it was Busch who first intentionally used templates in synthesis and who first articulated the concept of the template effect in the 1960s [12]. Busch used the reaction of a nickel(Il) dithiolate complex 7 with l,2-bis(bromomethyl)benzene 8 to illustrate his ideas (Scheme 1-3) [13]. Once one end of the l,2-bis(bromomethyl)ben-zene has reacted with the nickel complex, the nickel template induces the reactive ends of the intermediate 9 to come into close proximity and favors cyclization. The metal template allows the synthesis of a metallated macrocycle 10 the free ligand cannot be prepared by the reaction of l,2-bis(bromomethyl)benzene with the unbound thiol (in the absence of a template other cyclic and acyclic products are formed). 

Scheme 5.2. Structures of Ni-azacyclams complexes obtained by template synthesis. Reprinted from Scheme 5.1 R Abba, G. De Santis, L. Fabrizzi, M. Licchelli, A.M. Manotti Lanfredi, R Pallavicini, A. Poggi and F. Ugozzoh, Nickel (II) complexes of azacyclams Oxidation and reduction behavior and catalytic effects in the elctroreduction of carbon dioxide. Inorganic Chemistry 33 (1994) 1366-1375. Copyright 1994, with permission of American Chemical Society.

Thus, according to the purposes it is proved, that template synthesis leads to reception of the materials possessing selective properties in relation to template ion. The bioinorganic matrix of polymer (BIP-M) synthesized on ions of nickel in a series of tests proves as template sorbent possessing high absorbing selectivity to related ions and low to another s. So, factors of distribution for BIP-M in solutions with concentration 0.01 mol/l are (NP) =15.5 and (Cu ) =12.6. 

Thus, the template approach demonstrates the interesting behaviour of complexes based on pentan-2,4-dione bis-(5 -alkylisothiosemicarbazones). Some are also suitable precursors for constructing macrocyclic compounds. Of these open-chain complexes, the most useful have proved to be complexes of the [Ni (HL63)] family. These have been prepared by deprotonation of the species [Ni (H2L63)]I in ethanol/ammonia [93] or by template synthesis directly from the corresponding ligsons and a nickel salt in ethanol/water (1 1) in an inert atmosphere, followed by the addition of KOH [83]. 

By using the approach described [201], template synthesis of nickel(II) [202] and copper(II) [203] complexes of L165 and L166, which are isomeric with those of L163 and L164, was carried out according to reactions (Eq. 2.96). 

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