Melts metal complexes

Table 1 Hsts many of acetamide s important physical properties. Acetamide, CH2CONH2, dissolves easily ia water, exhibiting amphoteric behavior. It is slow to hydroly2e unless an acid or base is present. The autodissociation constant is about 3.2 x 10 at 94°C. It combines with acids, eg, HBr, HCl, HNO, to form soHd complexes. The chemistry of metal salts ia acetamide melts has been researched with a view to developing electroplating methods. The hterature of acetamide melts and complexes, their electrochemistry and spectroscopy, has been critically reviewed (9).

Detailed, critical surveys of the variants and complexities of crystal growth from the melt were published for low-melting metals by Goss (1963) and for high-melting metals (which present much greater difficulties) by Schadler (1963). 

The recoil-free fraction /a of transition metal complexes or proteins in frozen solution can be as small as 0.1-0.3, when measured just below the melting point, but the /-factor increases strongly when the temperature is lowered to fiquid nitrogen temperatures (77 K), and at fiquid helium temperatures (4.2 K) it may reach values of 0.7-0.9 [35]. This makes a substantial difference to the acquisition time of the spectra because of the square dependency on the signal (3.1). 

Solvent-soluble metal complex azo black dyes are used in both industrial ink jet printing and hot melt ink jet printing. Cl Solvent Black 35 (61) is a typical dye.48... 

Ferrocene is a very stable compound that melts at 173 °C and can be sublimed without disruption of the metal complex. Many reactions exhibited by ferrocene are essentially those of an aromatic organic compound. For example, sulfonation of ferrocene can be achieved as follows ... 

A series of complex silico-arsenides has been obtained 6 by melting metals with silicon and an excess of arsenic under a layer of molten cryolite and sodium chloride. The following have thus been prepared copper silico-arsenide, a grey crystalline brittle mass zinc silico-arsenide, which behaved as above with hydrochloric acid iron, cobalt and nickel siMco-arsenides, of composition M2SisAs4, similar in appearance to the copper compound. When platinum was treated in the same way, a hard white product of indefinite composition was obtained, almost insoluble in nitric acid. 

The first metal complex of quinuclidine (2) was reported in 1966.58 Ag(quinuclidine)2N03 was isolated as a white solid after reaction of quinuclidine and silver nitrate in acetonitrile for several days. The formation constants were determined in DMSO (Table 11). The complex melted with decomposition at 158 °C. 

Hopkins and co-workers [6] have used the selective complexation of transition metals by two distant EDTA modified amino acids to stabilize the a-helical conformation of peptides 2 and 3 (Fig. 3). The results were particularly impressive in the case of 3 where the helicity increased from 0 to about 80% upon complexation of Cd2 4 ions. Along the same lines, Ghadiri and coworkers [7] reported the important stabilization of the helical conformation of 4 and 5 by the formation of selective metal complexes (Ru2+, Zn2+, Cu2+, and Cd2+) involving either two imidazoles of histidines or one imidazole and one thiol from a cysteine separated by three amino acids (I, 1 + 4) (Fig. 4). They also reported that peptide 4 is Cd2+-selective and that the helical conformation of the inert Ru2+ complex of 5 is remarkably stable. For instance, it has a melting point 25 °C higher than the uncomplexed peptide in water. 

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