Complex adducts

Antimony pentafluoride is a strong Lewis acid and a good oxidizing and fluorinating agent. Its behavior as a Lewis acid leads to the formation of numerous simple and complex adducts. It reacts vigorously with water to form a clear solution from which antimony pentafluoride dihydrate [65277-49-8], SbF 2H2O, may be isolated. This is probably not a tme hydrate, but may well be better formulated as [H O] [SbF OH]. 

Complexes. The structure of an n a charge-transfer complex between quinoxaline and two iodine atoms has been obtained by X-ray analysis and its thermal stability compared with those of related complexes. The hydrogen bond complex between quinoxaline and phenol has been studied by infrared spectroscopy and compared with many similar complexes. Adducts of quinoxaline with uranium salts and with a variety of copper(II) alkano-ates have been prepared, characterized, and studied with respect to IR spectra or magnetic properties, respectively. 

The catalytic activity of the N4 complexes depends both on the nature of the central metal ion and on the nature of the ligand and aU substituents. It was found that the metal ion is the active site where the electrocatalytic process is accomplished. During its adsorption, an oxygen molecule forms a stable complex (adduct) with the... 

Solvent extraction is used in nnmerons chemical industries to produce pure chemical compounds ranging from pharmaceuticals and biomedicals to heavy organics and metals, in analytical chemistry and in environmental waste purification. The scientific explanation of the distribution ratios observed is based on the fundamental physical chemistry of solute-solvent interaction, activity factors of the solutes in the pure phases, aqueous complexation, and complex-adduct interactions. Most university training provides only elementary knowledge about these fields, which is unsatisfactory from a fundamental chemical standpoint, as well as for industrial development and for protection of environmental systems. Solvent extraction uses are important in organic, inorganic, and physical chemistry, and in chemical engineering, theoretical as well as practical in this book we try to cover most of these important fields. 

In our NMR studies 143,147,148,322-324) of amine and other adducts of Ni[R-dtp]2 complexes neat amines were employed in order to eliminate variations in extent of association (H-bonding) of the amines, to permit observation of NH proton shifts, and to maximize the concentration of the preferred adduct. The use of high concentration of primary amines in solutions with Ni[R-dtp]2 complexes can lead to products other than those expected, e.g., with aliphatic diamines, the R-dtp anion salts of f/zs(diamine)nickel(ll) chelates are obtained ). Furlani and co-workers ) have shown that Ni-(ethyl-dtp)2 reacts with n-butyl amine to yield complexes containing the NiS2N4 chromophore, presumably with monodentate ethyl-dtp. In all work with adducts it is necessary to assure that the complexes, adduct molecules and solvent systems are anhydrous. A number of authors 132,284,295,329) shown that Ni[ R-dtp ]2 complexes decompose when in contact with water. 

In conclusion, it appears that the classical ozonide 03 ion can be regarded as a well-characterized species on oxide surfaces. In contrast, the situation on the characterization of the so-called anomalous 03 complex is quite different. It is not possible at present to provide a clear theoretical explanation of the observed g values on the basis of an 03 species and the available I70 data is consistent with interaction with only two oxygen nuclei. The identity of this species must be regarded as uncertain at this stage and on the whole is more consistent with a complex adduct species, which may involve... 

Various stereochemical permutations are observed for octahedral tin complexes. Adducts of tin(IV) chloride and bromide generally exhibit the cis geometry (37), 240-247 although some examples of the trans geometry are known.248-252 Reasons for the preference for the cis... 

Urea dewaxing a continuous dewaxing process for producing low-pour-point oils, and using urea which forms a solid complex (adduct) with the straight-chain wax paraffins in the stock the complex is readily separated by filtration. 

Somewhat similar are the so-called adductive crystallization processes, often (wrongly) called extractive crystallization, where reactions of complex/ adduct formation are used to separate compounds that are otherwise difficult to separate. Examples of adductive crystallization include separation of p- and m-cresols (137), separation of o- and p - n i troch I oro ben zcn cs (138), separation of quinaldine and isoquinoline (139), separation of nonaromatic compounds from naphtha-cracking raffinate (140), and separation of p-cresol from 2,6-xylenol (141). Other examples of reactive crystallization/precipitation reported in the literature are listed in Table 5. 

Practically all transformations discussed in this section represent reactions of molecular complexes (adducts) formation. At the same time, it is necessary to take into account that, in some cases, more complex processes can take place, for example cyclometallation (3.226) [460], (3.227) [496], and (3.228) [497] ... 

The aromatic products often contain an arene-complexed chromium tricarbonyl unit. The metal-free product is obtained by oxidation commonly using CAN or air under irradiation. The formation of complexed adducts can be used to prepare chiral chromium tricarbonyl arene complexes (Scheme 44, see Arene Complexes). 

Chain growth differs from step growth in that it involves initiation and usually also termination reactions in addition to actual growth. This makes its kinetic behavior similar to that of chain reactions (see Chapter 9). However, the chain carriers in chain-growth polymerization need not be free radicals, as they are in ordinary chain reactions. Instead, they could be anions, cations, or metal-complex adducts. While the general structure of kinetics is similar in all types of chain-growth polymerizations, the details differ depending on the nature of the chain carriers. 

Later, a complete chromatographic resolution of Co(acac)3 and Cr(acac)3 on an optically active poly(triphenyhnethyl methacrylate) column was accomplished. The optical data of the pure enantiomers were obtained. Extensive use was made of columns composed of clay plus metal complex adducts. Thus, optical resolution was accomplished by LC on a column packed with an ion-exchange adduct of synthetic hectorite and optically active [Ni(II)](phen)3 and [Ru(II)](phen)3 . Using these systems, Co(acac)3, Cr(acac)3, Rh(acac)3 and [Co(acac)2(en)]+ (en = ethelenediamine) were resolved completely into enantiomers . Enantiomers of these four species were separated by LC on a column packed with ion-exchange adduct of synthetic hectorite and optically active metal complexes . One optically active metal complex used was tris(LlO-phenanthroline)-nickel(n), which was ion exchanged into synthetic hectorite. Racemic Co(acac)3, Cr(acac)3 and Ru(acac)3 were also enantiomerically separated via LC using poly(t-butylisocyanide) as stationary phase . ... 

In reality, the second possibility occurred (57), and the same was true for the adducts containing other olefins. Finally, we verified the presence of hydroxyl in structure (IV) through reaction with phenyl isocyanate. Thus, the convincing experiments of Hoffmann, Middleton, and R. Adams were confirmed by our decisive evidence, so that 7T-structures were condemned to fade from the scene for these compounds. However, to emphasize the behavioristic similarity with the 77-complcxes, I suggested the term quasicomplex for the compounds which are formed from metallic salts and olefins or acetylenes through addition to the 7T-bond. A number of such quasi-complex compounds were obtained and studied by us. In particular, we showed that butadiene or its homologs, contrary to the earlier opinion of Sand, also formed the quasi-complex adducts in water, e.g.,... 

We hope to have demonstrated that a OjO-conjugated system, if attacked at its extreme points, will undergo /3-elimination, e.g., the quasi-complex adducts will eliminate acetylene or olefin. Longer systems which include different alternations of a- and 77-conjugated systems are also possible. If a cr-bond is centered in a conjugated chain, an attack directed at, for example, the 1,6-position, will break the molecule. Such a reaction searched for and found by us (together with Freidlina and A. Kochetkov) is shown below 115, 116). 

The term addition compounds covers donor-acceptor complexes (adducts) and a variety of lattice compounds. The method described here, however, is relevant not just to such compounds, but also to multiple salts and to certain compounds of uncertain structure or compounds for which the full structure need not be communicated. 

Photolysis or thermolysis of diarylzirconocenes or arylalkylzirconocenes lead to reactive aryne-zirconocene complexes which can be trapped with several types of electron-donating ligands including dienes, phosphines, and carbon monoxide [13-15]. After being postulated by VoPpin et al. [14] and Erker [13], benzyne-zirconocene 1 (Eq. 1) was fully characterized by Buchwald et al. [16] by X-ray crystallographic studies of its trimethylphosphine complex adduct ... 

See also activated complex adduct charge-transfer COMPLEX ELECTRON-DONOR-ACCEPTOR COMPLEX ENCOUNTER COMPLEX INCLUSION COMPOUND PI (n) ADDUCT SIGMA (o) ADDUCT, TRANSITION STATE. 

Ethylenediamine is a common aliphatic chain chelate, and it forms very stable chelating compounds with a variety of transition metals. Howe and Lunsford incorporated Con-ethylenediamine complex into zeolites X and Y to form composite compounds that can adsorb oxygen.11731 In both zeolite cages the oxygen adduct [Con])(en)202]2+ may be formed, and this complex adduct is stable up to 70 °C in the presence of oxygen. The ESR parameters of the adduct are similar to those for the adduct in solution. 

The complexes of urea and thiourea with boron trifluoride have been studied and, as with other boron trifluoride complexes, the shifts are very similar namely 19 2+0-3 p.p.m. [with respect to (MeO)aB]. A similar shift was observed for the more complex adducts with cadmium chloride or nickel bromide. It was found that dimethyl ether-boron trifluoride (shift of 17-6) and di-t-butylthiourea-boron... 

The use of conventional low-molecular-weight emulsiners did not solve these problems. However, much progress has been made wifli flie introduction of amphiphilic macromolecules as emulsifiers. These multianchoring flexible macromolecules can improve the steric stabilization by forming thick multilayered coating on the droplets. A variety of hybrids, complexes, adducts between the am-phiphiles, and coemul-sifiers as cosolvents have been studied. These molecules improved the stability significantly and slowed the release rates. 

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