Preparation of metal -complexes

This reaction has been observed for porphyrins, and used to establish relative stabilities.51,53 It is of practical use in the preparation of metal complexes, e.g., metallophthalocyanines by metal exchange with dilithium(I) phthalocyanine.54... 

Although many complexes of Sc and Y can be seen in the literature, these complexes have been mostly used as Lewis acids in organic synthesis. There are a few examples where addition reactions of organometal species to C=0 double bond, C=N double bond, and C=N triple bond were used in preparation of metal complex. 

Introduction 231 Fundamental concepts 233 Electronic structure of transition-metal ions 235 Structural characteristics necessary for complex formation 240 Preparation of metal-complex colorants 248 Isomerism in metal-complex dyes 260 Stability of metal-complex dyes 261 Chromium-related problems in the mordant dyeing of wool 268 References 277... 

The preparation of metal complexes from hydroxypyridinones is usually simple and straightforward—the more difficult task is generally the synthesis of the required ligand. There may also be difficulties in separating complex from ligand, especially for the more lipophilic complex S sublimation, used in the case of A -n-hexyl, may be more successful than recrystallization. 3-Hydroxy-4-pyridinones are for the most part accessible from hydroxypyranones. Reagents developed for analytical and separation purposes (preparative methods may be traced back... 

Various routes have been used by many groups for the preparation of metal complexes with weakly bonded anions. These are... 

The well-known capacity to replace one ligand by another one was used for the preparation of metal complexes as far back as the nineteenth century. Such reactions can be illustrated by two examples [(3.89), (3.90)] [11] ... 

Motterlini RA, Mann BE (2002) Preparation of metal complexes for therapeutic delivery of carbon monoxide as vasodilator. Patent WO 2002/092075... 

As a first step toward this purpose, we have studied the chelation effect of tetrapeptides of sequences Cys-X-Y-Cys, by preparation of metal complexes of mainly the first transition series. The hydrophobic effect of the peptides was also studied by utilizing the side chain bulkiness of the amino acid residues interposed between the two cysteine residues. A special effect of aromatic side chains of tyrosine, phenylalanine, and tryptophan has also been examined in order to assess their ability to ease electron transfer to and from the nearby iron core. 

In addition to the above reactions, the preparation of metal complexes directly from 46 was also studied. Upon treatment of 46 with either Zn(II) or Cu(II) an immediate ring contraction occurred and the meso-substituted porphyrin derivatives 54 and 55 were again obtained. 

This method has been the most useful for the preparation of metal complexes. Several compounds containing main-group elements such as boron, gallium, indium, silicon, germanium, tin and lead as the metal are shown in equations 134 , 135, 136 , 13791.146, i3gi3i 139 , 140 and 141 . 

Syntheses are reported for 113 compounds along with resolution procedures for some metal complexes. Several organic ligands are included, but their inclusion is warranted, since they are of interest primarily for the preparation of metal complexes. In several cases metal ions play an important role in the template synthesis of the ligands. There are several chapters of nonmetals, including an interesting phosphorus ylide and some of its metal complexes. 

The use of metal phthalocyanine compounds has also been described (66,67). The catalysts can either be supported on an inert carrier or used in a liquid-liquid two-phase system. Various functionalized phthalocyanine ruthenium complexes have been mentioned for the reaction of interest. For instance, ruthenium phthalocyanine disulfonate transformed hept-3-ene into 3- -propylpentanol (80°C, 18 hours, 120 bar) in a two-phase system. Further details (67) on the preparation of metal complexes supported on silica- and alumina-type supports have appeared. Generally, a mixture of metal phthalocyanine sulfonate and hydrated alumina pro-... 

Out of a number of preparative routes described in Section II for preparing metal alkoxides, those involving (a) the metal-carbon bond cleavage reaction (Section II.F), (b) the chloride-alkoxide exchange reaction (Section II.C. 1), (c) the amido-alkoxo exchange reaction (Section II.E), and (d) the alcoholysis reaction (Section II.D) appear to be more convenient and versatile. Schemes 1-6 summarize some of the typical reactions studied for the preparation of metal complexes of alcohol ligands with large steric requirements. 

Since the heterocycle can have available to it more than one mode of coordination, preparation of metal complexes may lead to isolation of either kinetie or thermodynamic product. A tautomeric system like 4 5)-methylimidazole coordinates with Co(NH3)5 + to give a mixture of two isomers. The more sterically hindered of these (where the metal is ortho to the methyl group) can cyclize intramolecularly on heating to give the more remote isomer as the thermodynamic product <83IC2693>, and there are other similar examples <9UCS(D)303i>. 

The tetrahedral [CoCl(Tppll,vle) reacts with L (L = hydroxypyridinone, hydroxypyridinethione, pyrone, and thiopy-rone) giving [Co(L)(Tpph,Me)]. Single-crystal X-ray studies show that the [Co(L)(TpPh Me)] is pentacoordinate with a general tendency toward square pyramidal geometry.138 The molecular structure of [Co(N03)(Tpph,Me)(THF)] has been also reported.139 Mechanochemical synthesis of [NiCl(Tpph,Me)] has been developed, which enabled the preparation of metal complexes of... 

Cyclopentadiene is used in the manufacture of resins, in the synthesis of sesquiterpenes and camphors, and as a ligand in the preparation of metal complexes. 

Base for C-H or N-H Deprotonation of Precursors to Carbene or Amide Ligands in the Preparation of Metal Complexes. KHMDS has been used as a base for the deprotonation of N-H or B-H bonds in imine-based ligands or trispyrazolyl borate-derived ligands to synthesize calcium complexes, which were used as initiators of the ring-opening polymerization of lactides. A first example of a two-coordinate, neutral In singlet carbene complex has been prepared via an in situ deprotonation of the imine ligand precursor with KHMDS in the presence of In I to afford the In(I) complex in 36% unoptimized yield as pale yellow, thermally stable crystals. ... 

Figure 6-1. Two routes for the preparation of metal complexes as part of a...

Many of the first successful approaches concerned the preparation of metal complexes that resembled those observed at the active sites of metallo-enzymes. 

The preparation of metal complexes generally involves the reaction between a salt and some other molecule or ion (Chapter 4). Much of the early work was done with ammonia, and the resulting complexes were, and are, known as metal ammines. It was also found that anions such as CN, NO2, NCS, and Cl form metal complexes. Many compounds were prepared from these anions, and at first each was named after the chemist who originally prepared it (Table 1.1). Some of these names are still used, but it soon become apparent that the system of nomenclature was not satisfactory. 

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