Ethylenediamine, complexes Subject

Gianguzza and Orecchio [147] have carried out comparative trials of various methods for estimating nitrites in seawaters. These workers compared a method using sulfanilic acid/a-naphthylamine complexes with a method using sulfanilamide/N( 1-naphthyl) ethylenediamine complexes for the determination of nitrites in saline waters. The second method has the greater sensitivity and lower detection limits. The former method is subject to interference from chlorides, and this interference can be completely eliminated by the coupling diazotisation procedure of the latter method. 

The phenomenon was observed for the first time by Brdicka [13] in the reduction of riboflavin and methylene blue studied by d.c. polaro-graphy. It did not receive much attention until it was rediscovered by several workers studying systems such as Tl+/Tl(Hg), Pb2+/Pb(Hg), and the more obvious system Co(III)—Co(II)—tris-ethylenediamine using impedance measurements [14—16]. The confusion that arose initially in the literature around this subject in the end led to the correct theoretical description [15, 17, 18], the general treatment remaining very complex [18,19]. 

In addition, such a method of synthesis can be generated by making use of another destructive means for ligand synthesis. In that sense, the method was verified by achieving some polycondensation products of polyethylene terephthalate and ethylenediamine and their complexation with different metals by irradiating the system with cobalt-60 (gamma rays). These results also make up the subject of other studies. 

Ethylenediamine (en), diethylenetriamine (dien), triethylene-tetramine (trien), and tetraethylenepentamine (tetren) form well characterized complexes with M(ii) ions. Such complexes have been the subjects of a number of NMR exchange studies. (299-303) studies have established the identities of [Cu(en)(H20)4], [Cu(en)2-(HjOjj], and complexes involving both en and sulphosalicylic acid ligands. (299-301) NMR studies have been made on aqueous solutions of [Ni(dien)(H20)3], [Ni(tren)(H20)2], and... 

The mononuclear cations of chromium(III) and cobalt(lll) of the tetraammine and the bis(ethylenediamine) series belong to a class of complexes that has been most extensively studied. The present complexes will often prove useful as starting materials for preparing complexes within their class, and reactions with these complexes are likely to form the subject of many future investigations. 

The first reports of a reaction of an amine with an aldehyde by Schiff [584] led to the establishment of a large class of ligands called Schiff bases. Among the most important of the Schiff bases are the tetradentate salen ligands (N,N -bis(salicy-laldehydo)ethylenediamine), which were studied extensively by Kochi and coworkers, who observed their high potential in chemoselective catalytic epoxidation reactions [585]. The best known method to epoxidize unfunctionalized olefins enantioselectively is the Jacobsen-Katsuki epoxidation reported independently by these researchers in 1990 [220,221]. In this method [515,586-589], optically active Mn salen) compounds are used as catalysts, with usually PhlO or NaOCl as the terminal oxygen sources, and with a O=Mn (salen) species as the active [590,591] oxidant [586-594]. Despite the undisputed synthetic value of this method, the mechanism by which the reaction occurs is still the subject of considerable research [514,586,591]. The subject has been covered in a recent extensive review [595], which also discusses the less-studied Cr (salen) complexes, which can display different, and thus useful selectivity [596]. Computational and H NMR studies have related observed epoxide enantioselectivities... 

Perchlorates are powerful oxidizing substances. These compounds explode when mixed with combustible, organic, or other easily oxidizable compounds and subjected to heat or friction. Perchlorates explode violently at ambient temperatures when mixed with mineral acids, finely divided metals, phosphorus, trimethylphosphite, ammonia, or ethylenediamine. Explosions may occur when perchlorates are mixed with sulfur, or hydride of calcium, strontium, or barium and are subjected to impact or ground in a mortar. Perchlorates react with fluorine to form fluorine perchlorate, an unstable gas that explodes spontaneously. Heating perchlorates to about 200°C (392°F) with charcoal or hydrocarbons can produce violent explosions. Metal perchlorates from complexes with many organic solvents, which include benzene, toluene, xylenes, aniline, diozane, pyridine, and acetonitrile. These complexes are unstable and explode when dry. Many metal perchlorates explode spontaneously when recrystaUized from ethanol. Saturated solution of lead perchlorate in mathanol is shock sensitive. 

For Class B (substitution labile) metal complexes, reequilibration to more thermodynamically favorable coordination modes will be very rapid relative to immobilization. Such behavior is typical of first-row TM complexes. In addition, these ions are usually very oxophilic, so the metal complexes are typically subject to ICC interactions with oxide materials. Since these metal ions are generally immobilized under conditions of thermodynamic control, all pertinent speciation equilibria, including ICC reactions (Section III.B), must be considered in order to understand or predict the outcome of immobilization reactions. It is essential to understand the relevant equilibria if direct imprinting of active site structures is to be successful. The studies of Klonkowski et al. (210-213), for example, underscore this point Sol-gel immobilization of copper complexes bearing silylated amine and ethylenediamine ligands were shown by EPR to result in multiple copper environments, suggesting competition between immobilization and ICC reactions. 

The transesterification of N-(j3-hydroxyethyl)ethylenediamine by p-nitro-phenyl picolinate has been shown to be subject to zinc ion catalysis by Sigman and Jorgensen 27). Their investigations indicate that reaction very probably occurs through the formation of a ternary complex in which zinc ion functions both to lower the pKa of the hydroxyethyl moiety, and to serve as a template for the reaction. The high specificity manifest in this catalytic process is emphasized by the fact that no catalysis of acyl-group transfer occurs when N-((8-hydroxy-ethyl) ethylenediamine is replaced by ethylenediamine, 1,5-diaminopentane, di-ethylenetriamineor aminoethanol. Furthermore, the reactions of the p-nitrophenyl esters of isonicotinic and acetic acids with N-((8-hydroxyethyl) ethylenediamine are not subject to zinc ion catalysis. 

Pechini route. The solution of corresponding nitrate salts and tetraethoxysilane in ethanol was mixed with complexation/polymerization agents citric acid (CA), ethylene glycol (EG) and ethylenediamine (ED). The molar ratios of CA EG metal ions (Me) in the solution were 3 15.2 1 when only EG was used as polymerization agents [52]. When both EG and ED were used, the molar ratios of CA EG ED Me were 3.75 11.25 3.75 1. The mixed viscous solution was heated until the formation of a transparent polymeric gel which was then calcined at 50-1200°C. In some cases, the precursors calcined at 600°C were subjected to the mechanical activation for 5 min before further calcination. The composition and synthesis conditions for some samples are presented in Table 2. 

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