Mercury complexes thiourea

Dithiocarbamates and thioureas are included in this section because of their useful electrochemical behavior at mercury and mercury amalgam electrodes. The formation of mercury complexes results in an easy oxidation at the mercury electrode. On the other hand, carbon electrodes are not well suited for the detection of these compounds because the oxidation occurs beyond the usual scope of carbon detector cells. 

HgS films have also been deposited from more conventional deposition solutions using thiourea and the tetraiodide complex of mercury—a strong complex—in alkaline solution. Both these and the previous films showed an optical absorption with a gradual absorption onset at 700 nm and a sharp one at 400 nm. 

Both 1 1 and 2 1 complexes of Af,.ZV-diethyl- and N,iV-dimethyl-thiourea with zinc, cadmium and mercury halides have been prepared. The 2 1 complexes are either monomeric and tetrahedral or polymeric and halogen-bridged with octahedral metal coordination the 1 1 complexes also possess a polymeric, halogen-bridged structure, but with tetrahedral metal coordination.894 5... 

Four different thiourea complexes of mercury(II) are easily prepared from aqueous solutions of mercury(II) chloride and thiourea. The proportions of reagents are not as critical as the temperature, elevation of which results in precipitation of black mercury (II) sulfide. Electrical conductivities and freezing points provide evidence for the constitution of the complexes. 

Thiourea, mercury(II) chloride complexes with, 6 26 Thorium, powder by reduction of oxide with calcium, 6 50 removal of, in extraction of... 

Thiourea is known to form a series of complexes HgCl2Lrt (n = 1 — 4, L = thiourea). Structural studies on the complexes n = 2 or 4 have now been reported. The crystal structure of HgCl2L2187 shows the mercury to be co-ordinated in a distorted trigonal coplanar conformation by two equivalent thiourea sulphur atoms (Hg—S = 2-42 A) and a chlorine atom (Fig—Cl = 2.57 A). The other ionic chlorine atom lies normal to this plane, between and equidistant from a pair of mercury atoms (Hg—Cl = 3.22 A). 

A combination of IPC and inductively coupled plasma (ICP) MS was extensively explored for the speciation of phosphorus, arsenic, selenium, cadmium, mercury, and chromium compounds [108-118] because it provides specific and sensitive element detection. Selenium IPC speciation was joined to atomic fluorescent spectrometry via an interface in which all selenium species were reduced by thiourea before conventional hydride generation [119], Coupling IPC separation of monomethyl and mercuric Hg in biotic samples by formation of their thiourea complexes with cold vapor generation and atomic fluorescence detection was successfully validated [120]. The coupling of IPC with atomic absorption spectrometry was also used for online speciation of Cr(III) and Cr(VI) [121] and arsenic compounds employing hydride generation [122]. 

In the presence of millimolar concentrations of stronger nucleophiles such as CN and thiourea for Pt + complexes, or molar concentrations of Cl for Hg+ complexes, nncleic acid base substitution takes place. However, steric constraints can lead to surprising inertness, as demonstrated for N-3-platinated T and U. In contrast to coordination bonds of Hg + to heterocyclic N-atoms of nucleic acid bases, the covalent bond of mercury ion to C-5 of pyrimidines see Mercury Organometallic Chemistry) is stable even in the presence of 1M NaCl. ... 

Selenourea is less stable than urea or thiourea, as it is sensitive to air and light, particularly in solution, and tends to dimerize in certain systems. In general, the donor properties of selenourea are similar to those of thiourea,2.3 and complexes with cobalt(II),4,5 palladium(II), platinum(n), zinc, cadmium, and mercury acceptors can be obtained by appropriate modification of the methods used for the preparation of the analogous thiourea derivatives. 

Complexes of thiourea with mercury(II) halides have been known for almost a century, and compounds containing one, two, three, or four molecules of coordinated thiourea can be isolated from aqueous solution. With selenourea in acetone, it is possible to prepare 1 2 complexes Hg[(NH2)2CSe]2X2 (X = C, Br, I) and a dimeric 1 1 complex [Hg (NH2)2CSe Cl2]2 in excellent yields. 

Inorganic complexing reagents such as Hg(N03)2, AgNOs, NiS04 and KCN can be used for complex-formation titrations. Mercury(II) ion forms neutral complexes with most of the anions that precipitate with silver nitrate such as Br, CD, SCN, CN and thiourea. 

ASH] Ashcroft, S. J., Thermochemistry of thiourea complexes of the type [M (tu)4Cl2] (M = manganese, iron, cobalt, nickel, zinc, cadmium and mercury, J. Chem. Soc. A, (1970), 1020-1024. Cited on pages 128, 129,338. 

Cadmimn, copper, mercury, silver, and tin form white precipitates with thiourea when present in high concentrations. Only antimony(III) (and vanadate) gives a weak yellow color with thiourea. Hg, SeOj and SeO " are reduced and interfere by forming colored complexes and precipitates. ... 

CungFeNgSu, Bis(isothiocyanato)bis(thiourea)irondl), 46B, 983 CftH8HgNgS2, Bis(thiourea)dicyanomercury(II), 37B, 615 CijHgHgNgSu, Mercury(II) thiocyanate-thiourea complex, 28, 113 31B, 401... 

The separation of solvent effects on reactivities into constituent initial-state and transition-state effects by the use of appropriate kinetic and thermodynamic data has been successfully carried out for several organic reactions. Thus, for example, the solvolysis of t-butyl chloride and the Menschutkin reaction were treated in this manner some time ago a recent organic example is afforded by the solvolysis of isopropyl bromide in aqueous ethanol. For inorganic reactions, this approach was early used for reactions of tetra-alkyltin(iv) compounds with mercury(ii) halides. A more recent analysis of reactions of low-spin iron(n) complexes with hydroxide and with cyanide in binary aqueous mixtures was complicated by the need to make assumptions about single-ion values in such ion+ion reactions. Recent estimates of thermodynamic parameters for solvation of complexes of the [Fe(phen)3] + type are helpful in this connection. However, it is more satisfactory to work with uncharged reactants when trying to undertake this type of analysis of reactivity trends. A suitable system is provided by the reaction of [PtClaCbipy)] with thiourea. In dioxan-and tetrahydrofuran-water solvent mixtures, reactivity is controlled almost entirely... 

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