Metal ions dimethylformamide

Tris(o-hydroxyphenyl)triazine possesses structural features similar to 8-hydroxyquinoline. Linear polymers can be prepared by reaction of this trifunctional ligand with divalent metal salts in solution (32, 34). Reaction in bulk leads to the formation of cross-linked network polymers. Exactly how the difference in polymer structures [31] and [32] was determined was not made clear because both products were insoluble and infusible. It was postulated that the linear structure was obtainable because it precipitated from the reaction solvent before reaction with a third metal ion. Dimethylformamide was used in conjunction with an alcohol, such as methanol or ethanol, for the solution reaction. Temperatures up to 330°C were used for the bulk reaction. 

The polarographic determination of metal ions such as Al3 + which are readily hydrolysed can present problems in aqueous solution, but these can often be overcome by the use of non-aqueous solvents. Typical non-aqueous solvents, with appropriate supporting electrolytes shown in parentheses, include acetic acid (CH3C02Na), acetonitrile (LiC104), dimethylformamide (tetrabutyl-ammonium perchlorate), methanol (KCN or KOH), and pyridine (tetraethyl-ammonium perchlorate), In these media a platinum micro-electrode is employed in place of the dropping mercury electrode. 

Angeltr—>has briefly reported in a patent the addition of metal ions to several types of polyimides. The object of the invention was a process for forming particle-containing (transparent polyimide shaped structures. Unlike the work discussed previously, all of the metals were added in the form of coordination complexes rather than as simple anhydrous or hydrated salts. The properties of only one film (e.g. cast from a N,N-dimethylformamide(DMF) solution of 4,4 -diaminodiphenyl methane, pyromellitic dianhydride and bis(acetylacetonato)-... 

Fig. 4. Limiting single ion mobilities vs. reciprocal of estimated crystallographic radii of alkali metal ions AN, acetonitrile NM, nitromethane DMF,dimethylformamide PY, pyridine NB, nitrobenzene DMSO, dimethylsulfoxide EC, ethylene carbonate...

It is unrealistic to treat molecules of solvents such as N,N-dimethylformamide (DMF) as spheres in estimating AV for solvent exchange as for water. One can, however, anticipate that solvents which have unusually open structures because of extensive hydrogen bonding (notably water) will lose a relatively large fraction of their molar volume V on coordination to a metal ion, whereas for dipolar aprotic solvents this fraction will be much less, with partially H-bonded solvents... 

Table 4.4 Kinetic Parameters for Dimethylformamide Exchange of First-Row Divalent Transition Metal Ions, M(dmf)2+ at 25°C Refs. 27, 29...

The oxidation-reduction potentials of metal ions differ in different solvents due chiefly to differences in the strength of coordination of the solvents to the metal ions. Thus, Schaap and coworkers,33 who measured reduction potentials polarographically in anhydrous ethylenediamine, found the order of half-wave potentials to be Cd2+ > Pb2+ > Cu2+ - Cu+ > Ti+, whereas, in aqueous solution, the order is Cd2+ > Ti+ > Pb2+ > Cu2+ -> Cu+. Oxidation—reduction potentials have been measured in a great variety of non-aqueous solvents, both protonic and non-protonic. Among the former are liquid ammonia and concentrated sulfuric acid.34 Among the latter are acetonitrile, cyanopropane, cyanobenzene, dimethyl sulfoxide, methylene chloride, acetone, tet-rahydrofuran, dimethylformamide and pyridine.34... 

Inorganic radicals and transition metal ions typically exhibit broad lines, and hence diminished sensitivity in the EPR method. Consequently, when dealing with small quantities of paramagnetic material, it is often more difficult to detect inorganic species. Several important studies have been reported, however. Kastening s study [64] of the reduction of S02 in dimethylformamide showed that an equilibrium was established between the SO radical ion and the dimer S20, ... 

Hexaza 18-crown-6 151 (7.8%) and 152 (8.0%) have also been synthesized by treatment of 2,6-fc(chloromethyl)pyridine with jym-dimethylethylenediamine or piperazine in dimethylformamide, utilizing potassium carbonate as the base. The cobalt(II) and copper(II) complexes 153 of 151 have been made and the single crystal X-ray structure determination of each shows that in both cases the metal ion is octahedrally coordinated by the six nitrogen atoms of the ligand. In the case of... 

The electrochemistry of the polymeric and isomorphous cobalt(II) and nickel(II) methylsquarates was also studied by Iwuoha et al. In aqueous solutions, they found evidence that both the nickel(II) methylsquarate and its cobalt analog were dissociated without any reversible redox processes occurring for the metal ions. However, the cyclic and Osteryoung square wave voltammograms, obtained using a Pt electrode for solutions of these complexes in dimethylformamide and dimethylsulfoxide, contained signals attributable to both ligand-based and metal-based redox processes 142). 

Scheme 9.3 shows an example of an ionic gel adsorbing metal ion. A suspension of ionic gel (1) was gently stirred at 30 °C in a solution (orange color) of Pd-(OAc)2 in dimethylformamide. The orange supernatant became colorless after a few... 

The oxidation of thiols is accelerated remarkably by traces of catalyst and this reaction forms the basis of petroleum sweetening processes. Although transition metal ions are the most effective catalysts, any additive capable of catalysing electron transfer accelerates the reaction. Nitrobenzene in dimethylformamide/potassium hydroxide [118], 2-nitro-thiophene, tetracyanoethylene, and 4-nitropyridine-N-oxide [118] are all good catalysts for the oxidation of 1-butane thiol. The alkaline hydrolysis of disulphides containing aryl, carbonyl, and alpha unsaturated groups also results in catalysis, apparently due to the setting up of a sulphinate—sulphenate redox cycle [119—121]. 

Although the ratio of biaryls formed in these halogenative oxidations is somewhat sensitive to the reaction medium, it is noteworthy that the amount of biaryl formation is quite dependent both on the nature of the solvent and the metal ion (L, Na" ", or K+). Although potassium phenyl(tri-/7-tolyl)borate (58) dissolved in chloroform reacted with iodine to yield a 1.4 1.0 ratio of biaryl to p-iodotoluene, the same reaction in dimethylformamide gave almost exclusively p-iodotoluene. Likewise, the sodium analog of 58 gave a biaryl p-iodotoluene ratio of 1 32 (48). 

The ligand substitution reactions of the bivalent first-row transition metal ions are the most studied of those of the labile metal ions, probably because the visible d-d spectra of the transition metal ions make them particularly amenable to spectrophotometric study, and also because their reaction timescale is usually well within those of the SF and NMR techniques. Thus it has been shown that the mechanism of dimethylformamide (dmf) exchange on [M(dmf)6] (M = Mn—Ni) varies systematically from L to D, in contrast to the analogous [M(solvent)6] in water, methanol, and acetonitrile where the mechanism varies from L h the number of d electrons increases. This has occasioned a spectrophotometric SF study of the closely related substitution of the bidentate ligands trans-pyndine-2-azo(p-dimethylaniline) (Pada) and diethyldithiocarbamate (Et2DTC) on [M(dmf)6] shown in Eq. (13) (where L-L represents a bidentate ligand) which... 

Rate constants for the incorporation of several metal ions of the first transition series into N-methyltetraphenylporhyrin in N,N-dimethylformamide solution have been determined by Bain-Ackerman and Lavalle [36], Table 1.8.The rate order parallels that of the solvent exchange of the metal ions. Thus rapid solvent exchange in the d Jahn Teller distorted connerCII) leads to a rapid incorporation rate. 

Interaction of iodides on non-transitional metals in dimethylformamide. The iodides of the bivalent and tervalent ions of non-transitional elements... 

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