Square planar systems, synthesis

Thus, in examples of synthesis of tetraazamacrocyclic compounds on nickel ions (mainly) and on copper(II), square-planar system assembling is realised [38,47-49]. Guanidium ion promotes building of 27-crown-9-ether [60]. o-Aminobenzaldehyde self-condensation on the copper ion as matrix results exclusively in forming a complex with TAAB [67]. When using nickel(II) or cobalt(II) as templates under the same conditions, two types of macrocyclic azomethine systems - TAAB and TRI - may be synthesised [67-71]. Macrocychsation of phthalonitrile on the anisotropic matrix 0=U=0 ends with obtaining the so-called superphthalocyanine product [U02(L29)] [72, 73], rather than with the isolation of the corresponding complex with the phthalocyanine (Pc), as observed for other metal ions (Eq. 1.18) [11,74]. 

Considering the synthesis of an artificial system with coordinative or covalent bonds in square planar metal chelates for binding small molecules or catalytic use, main points are donor ligand activation, reduced aggregation, and irreversible oxidation of the chelate. 

An especially interesting mixed-valence double salt was obtained from the equilibrium mixture in the redox system Te/12/r, which is described in Section III,B for the synthesis of Tel4 . With benzyl-trie-thylammonium cations the compound [(C7H7)(C2H5)3N]4[Te l4] [Te Iel could be crystallized, which contains the two kinds of mononuclear iodotellurate anions with different oxidation numbers 107,108). The square planar Tel4 ions (mean Te-I 2.956 A) are connected to form layers through weak intermolecular I- T interactions (4.218 A) a similar association to layers (I-T 4.191 A) is observed for the slightly distorted Tele octahedra (mean Te-I 2.925 A). The unit cell is shown in Fig. 32. 

Equally strong interactions do not necessarily have to exist in square planar binuclear complexes, a problem that is of great concern to us. There is very little information in the literature about the synthesis or properties of such materials. Possibly planar binuclear systems are the ethanetetraaldehyde-bridged nickel aminotroponeiminato complexes, 2, reported by Trofimenko (26). The preparation of the bisimidazole complexes 3 was described (27) of which the tetracarbonyl derivatives might well be the very first example of completely planar binuclear transition metal compounds that are capable of extended interactions. 

Further work has been reported on the synthesis of complex phosphine-based ligand systems via the coordination-promoted self-assembly of simpler phosphines bearing appropriate functional groups. A series of ligands bearing one to four mem-substituted diphosphinoarene groups attached to a central core has been prepared and self-assembled via coordination to silver. Also reported is a route to the pyrene-appended phosphine (122), which, when coordinated to rhodium in a square-planar complex via the P and S centres, forms a self-assembled tweezer system in which two nearby pyrenyl... 

Bazan reported on the synthesis of pseudo-tetrablock copolymers comprised of ethene and 5-norbomen-2-yl acetate, using the initiator system (LiPr2)Ni(q -CH2Ph) (PMes) [(LiPr2) = 77-(2,6-diisopropylphenyl)-2-(2,6-diisopropylphenylimino) propanamide] and 2.5 equivalents of Ni(cod)2 [bis(l,5-cyclooctadiene)nickel [121, 130, 131]. Square-planar nickel complexes with anionic P,0-chelate ligands were used by Goodall and coworkers for the co- and terpolymerization of norbomene and 5-norbomene-2-carboxylic acid ethyl ester with ethene [126]. 

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