Metal cyanide complexes

The photocatalytic activity of silica-supported Ti02 materials has been evaluated with different model pollutants, such as potassium cyanide, metal-complexed cyanides, alcohols, organic dyes, pesticides and organochloride compounds (see Table 16). The photocatalytic experiments have been carried out in different photocatalytic reactors, using both UV lamps and the solar light [549-552]. 

Ion exchange is used in the metal plating industry to purify rinse water and spent plating bath solutions. Cation exchangers ranove cationic metal species, such as Cu, from such solutions. Anion exchangers remove anionic cyanide metal complexes, such as Ni(CN), and chromium(VI) species, such as CrOI. Radionuclides can be ranoved from radioactive and mixed radioactive/ hazardous chemical waste by ion exchange resins. 

Dehalogenation of monochlorotoluenes can be readily effected with hydrogen and noble metal catalysts (34). Conversion of -chlorotoluene to Ncyanotoluene is accompHshed by reaction with tetraethyl ammonium cyanide and zero-valent Group (VIII) metal complexes, such as those of nickel or palladium (35). The reaction proceeds by initial oxidative addition of the aryl haHde to the zerovalent metal complex, followed by attack of cyanide ion on the metal and reductive elimination of the aryl cyanide. Methylstyrene is prepared from -chlorotoluene by a vinylation reaction using ethylene as the reagent and a catalyst derived from zinc, a triarylphosphine, and a nickel salt (36). 

Cyanide phosphine complexes of transition metals. P. Rigo and A. Turco, Coord. Chem. Rev., 1974,13,133-172 (151),... 

Entries where the oxidation state of a metal has been specified occur after all the entries for the unspecified oxidation state, and the same or similar entries may occur under both types of heading. Thus cyanide appears under Chromium complexes, Chromium(O) complexes, Chromium(I) complexes, etc. More specific entries, such as Chromium, hexacyano-, may also occur. Similar ligands may also occur in different entries. Thus a carboxylic acid-metal complex may occur under Carboxylic acid complexes, under entries for specific carboxylic acids, and under the specific metal. Coordination complexes may also be listed in the Cumulative Formula Index. 

The Lewis bases attached to the central metal atom or ion in a d-metal complex are known as ligands they can be either ions or molecules. An example of an ionic ligand is the cyanide ion. In the hexacyanoferrate(II) ion, [Fe(CN)6]4, the CN- ions provide the electron pairs that form bonds to the Lewis acid Fe2+. In the neutral complex Ni(CO)4, the Ni atom acts as the Lewis acid and the ligands are the CO molecules. 

The biosorption capacity of Aspergillus niger was much greater than that of brewery yeast, and the biosorption capacity of metal-cyanide anion complexes was significantly lower than that of metal ion only. 

Luque-Almagro VM, M-J Huertas, M Martmez-Luque, C Moreno-Vivi an, MD Roldan, LJ Garcfa-Gil, F Castillo, R Blasco (2005) Bacterial degradation of cyanide and its metal complexes under alkaline conditions. Appl Environ Microbiol 71 940-947. 

In addition to the need for an adequate method for free cyanide and an adequate sample preservation method, a methodology should be developed for the differentiation of species, especially between free (HCN and CM ), metallic complexes, and organic complexes. 

Most low-valence metal complexes are generally deactivated by air and sometimes also by water. Carbon monoxide, hydrogen cyanide, and PH3 frequently act as poisons for these catalysts. Poisoning by strongly co-ordinating molecules occurs by formation of catalytically inert complexes. An example is the poisoning of Wilkinson s catalyst for alkene hydrogenation ... 

After these subcategorization bases were evaluated, raw waste characterization was selected as the basis for subcategorization. The raw waste characterization is divided into two components, inorganic and organic wastes. These components are further subdivided into the specific types of wastes that occur within the components. Inorganics include common metals, precious metals, complexed metals, hexavalent chromium, and cyanide. Organics include oils and solvents. 

The cyanide exchange on [M(CN)4]2 with M = Pt, Pd, and Ni is a rare case in which mechanistic comparisons between 3d, 4d, and 5d transition-metal complexes. Surprisingly, the behavior of these metal square-planar centers leads to mechanistic diversity involving pentacoordinated species or transition states as well as protonated complexes. The reactivities of these species are strongly pH-dependent, covering 15 orders of magnitude in reaction rates.85... 

X. Wu, X. Li, F. King, J. Xiao, Angew. Chem. Int. Ed. 2005, 44, 3407. Surprisingly, no direct references to cyanide inhibition of hydrogenation catalysts could be found. For a general reaction showing the swift reaction of a transition metal complex with cyanide as a means to isolate the ligand, see for ex-... 

Carbon-13 NMR was utilized to study different aspects of the reactivity of the metal complexes as a function of certain structural features in the selected oxocyano complexes of Mo(IV), W(IV), Tc(V), Re(V), and Os(VI) as depicted in Scheme 1 and illustrated in Figs. 1-4. The NMR spectral properties were similar to those obtained from 13C NMR in general, i.e., very sharp lines indicative of fairly long relaxation times in the order of a few seconds. The large quadrupolar moment ofTc-99 (7 = 9/2, 100% abundance) led to a very broad bound 13C signal (Fig. 5), thus excluding the quantitative study of the cyanide exchange by 13C NMR. However, 16N NMR was successfully used instead. 

Boucabeille C, Bories A, Ollivier P, et al. 1994b. Microbial degradation of metal complexed cyanides and thiocyanate from mining wastewaters. Environ Poll 84(l) 59-67. 

Oxidizing agents have been shown to be extremely effective for removing many complex organics from wastewater, including phenols, cyanide, selected pesticides such as ureas and uracils, COD, and organo-metallic complexes [11]. Many oxidants can be used in wastewater treatment. Table 9 shows the oxidation potentials for common oxidants [24]. The most widely used oxidants in the... 

Copper(i).—Halides and Cyanides.cation, [Me2N=CH2] , which has been reported previously by Eschenmoser (Symposium on Stereochemistry, Sheffield, 1970) is potentially useful in stabilizing low-valent metal complexes, and its reaction with Cu(CO)Cl has been examined. The results are outlined in Scheme 9. 

Optically active a-amino acids are prepared by a cyanide addition to imines, known as the Strecker reaction. Several organobase catalysts and metal complex catalysts have been successfully applied to the asymmetric catalytic Strecker amino... 

Sodium nitroprusside is the only clinically used metal complex of NO, so that its reactions provide an indication of the types of reactivity that metallonitrosyl complexes might be expected to have in physiological environments (see Fig. 1). The in vivo activation of nitroprusside depends on its reduction to [Fe(CN)5NO], which then releases cyanide to give [Fe(CN)4NO] which in turn releases NO and additional CN to yield Fejl,) and [Fe(CN)g] [75]. [Fe(CN)5(NO)] is paramagnetic (g, = 1.9993, g, = 1.9282, g = 2.008,... 

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