Phthalimide metal complexes

Yet another structural principle is represented by metal complex pigments based on isoindolinones. Condensation of amino-iminoisoindolinones (imino-phthalimide) with 2-aminobenzimidazole in a high boiling solvent affords an azomethine (36). This compound reacts with salts of divalent metals, such as Co, Cu, Ni, to yield yellow azomethine metal complex pigments [10] ... 

Guanidine forms salts with such relatively weak acids as nitromethane, phthalimide, phenol and carbonic acid [20], Interactions between carboxylate anions of proteins and added guanidinium ion are thought [19, 56] to be weaker than the interactions with ammonium ions the role of guanidinium-carboxylate interactions in stabilizing natural protein conformations has been discussed [36c]. A few reports of metal complex formation by guanidines [57-60], and aminoguanidines [61] have appeared. 

Phthalimide, JV-thio-metal complexes, 800 Phthalocyanines, 863-870 chelate complexes, 374 demetallation, 863 IR spectra, 861 mass spectra, 861 metallation, 863 NMR, 861 photochemistry, 869 reactions, 863 at metal, 869 redox chemistry, 870 spectra, 860 synthesis, 861 two-metal complexes, 868 Phytic acid zinc complexes, 985 2-Picoline... 

The phthalocyanines, naphthalocyanines, and certain of their metal derivatives (Figure 6.17) are infrared fluorophores. 61"64 As a class, they are exceptionally stable compounds, with copper (Cu) phthalocyanine (not a fluorophore) remaining intact above 300 °C in air. First used for textile dyeing in the last century and still widely used, there is a rich chemistry of phthalocyanines. Most derivatives can be made by prolonged heating of a phthalimide or phthalic acid derivative with a metal in powder or salt form at elevated temperature. Several derivatives absorb in the near-IR, and either fluoresce or phosphoresce. The electronic transitions of phthalocyanines are complex and have been extensively studied, at least in part because the symmetry of the molecule makes theoretical calculations of its spectroscopic behavior more tractable. Unsubstituted phthalocyanines and naphthalocyanines are, as a class, very insoluble in solvents other than, for instance, nitrobenzene. Sulfonated phthalocyanines are water soluble and exhibit spectra comparable to the parent derivative. Photolumines-cent phthalocyanines (Pcs) include SiPc, ZnPc, and PC itself. These compounds have been little used for practical infrared fluorometry to date however, Diatron Corpora-... 

History. Braun and Tschemak [23] obtained phthalocyanine for the first time in 1907 as a byproduct of the preparation of o-cyanobenzamide from phthalimide and acetic anhydride. However, this discovery was of no special interest at the time. In 1927, de Diesbach and von der Weid prepared CuPc in 23 % yield by treating o-dibromobenzene with copper cyanide in pyridine [24], Instead of the colorless dinitriles, they obtained deep blue CuPc and observed the exceptional stability of their product to sulfuric acid, alkalis, and heat. The third observation of a phthalocyanine was made at Scottish Dyes, in 1929 [25], During the preparation of phthalimide from phthalic anhydride and ammonia in an enamel vessel, a greenish blue impurity appeared. Dunsworth and Drescher carried out a preliminary examination of the compound, which was analyzed as an iron complex. It was formed in a chipped region of the enamel with iron from the vessel. Further experiments yielded FePc, CuPc, and NiPc. It was soon realized that these products could be used as pigments or textile colorants. Linstead et al. at the University of London discovered the structure of phthalocyanines and developed improved synthetic methods for several metal phthalocyanines from 1929 to 1934 [1-11]. The important CuPc could not be protected by a patent, because it had been described earlier in the literature [23], Based on Linstead s work the structure of phthalocyanines was confirmed by several physicochemical measurements [26-32], Methods such as X-ray diffraction or electron microscopy verified the planarity of this macrocyclic system. Properties such as polymorphism, absorption spectra, magnetic and catalytic characteristics, oxidation and reduc-... 

Equations (II) to (IX) illustrate basic methods of preparation, but many variations are used, particularly in industry, to obtain an economic yield. Phthalic acid, phthalamide, phthalimide, and phthalic anhydride, together with urea, are often used instead of phthalonitrile, and catalysts such as ammonium molybdate or zirconium tetrachloride may be employed (249, 251, 269). The reaction between phthalonitrile and metals (finely divided or acid-etched) is usually very vigorous at 250°-300°C, sufficient heat being generated to maintain the reaction temperature. This is an illustration of the ease with which the phthalocyanine skeleton is formed. Even more surprising are the observations that palladium black (118) and gold (189) will dissolve in molten phthalonitrile. Reaction (III) between phthalonitrile and a finely divided metal, metal hydride, oxide, or chloride is perhaps the most generally employed. For the unstable phthalocyanine complexes such as that of silver (11), the double decomposition reaction... 

Our return to amination chemistry was inspired by the mechanistic studies of the Ullman reaction (Scheme 8). Hartwig had shown that the Cu(I)-phthalimide complex (38) could undergo oxidative addition with aryl halides to form a Cu(lll) intermediate (39), which then reductively eliminated to form a C—N bond (40). We hypothesized that a Cu(III)-phthalimide intermediate (42) could also be created by oxidation of 38 and a subsequent C—H metalation, presumably via a CMD mechanism (Scheme 8). Consequently, we synthesized 38 and reacted it with a series of oxidants and arenes in an attempt to discover a synthesis of protected anilines (e.g., 40) via C-H activation. The initial reactions were performed using stoichiometric amoimts of 38, but we intended to lower the catalyst loading once a lead reaction was discovered. 

Template reactions are those in which formation of a complex places the ligands in the correct geometry for reaction. One of the earliest was for the formation of phthalocyanines (Figure 12.17). The study of this chanistry began in 1928, after discovery of a blue impurity in phthalimide prepared by reaction of phthalic anhydride with ammonia in an enameled vessel. This impurity was later discovered to be an iron phthalocyanine complex, created from iron released into the mixture via a scratch in the enamel surface. A similar reaction takes place with copper intermediates isolated from this reaction are shown in Hgure 12.17. Phthalic acid and ammonia first form phthalimide, then l-keto-3-iminoisoindoline, and then l-amino-3-iminoisoindolenine. The cyclization reaction then occurs, probably with the assistance of the metal ion, which holds the chelated reactants in position. This is confirmed by the lack of cyclization in the absence of the metals. The essential feature of these reactions is the formation of the cyclic compound by coordination to a metal ion. 

Because the reactions of related in -cyclohexadienyl complexes are synthetically valuable, the reactions of this ligand have been studied extensively. An outline of how this chemistry can be conducted on the Fe(CO)j fragment is shown in Equation 11.51. A variety of cyclohexadienes are readily available from Birch reduction of substituted aromatics. Coordination and abstraction of a hydride, typically by trityl cation, leads to cationic cyclohexadienyl complexes. These cyclohexadienyl complexes are reactive toward organolithium, -copper, -cadmium, and -zinc reagents, ketone enolates, nitroal-kyl anions, amines, phthalimide, and even nucleophilic aromatic compounds such as indole and trimethoxybenzene. Attack occurs exclusively from the face opposite the metal, and exclusively at a terminal position of the dienyl system. This combination of hydride abstraction and nucleophilic addition has been repeated to generate cyclohexa-diene complexes containing two cis vicinal substituents. The free cyclohexadiene is ttien released from the metal by oxidation with amine oxides. ... 

---