Mercury complexing

The most general method for synthesis of cyclic enamines is the oxidation of tertiary amines with mercuric acetate, which has been investigated primarily by Leonard 111-116) and applied in numerous examples of structural investigation and in syntheses of alkaloids 102,117-121). The requirement of a tram-coplanar arrangement of an a proton and mercury complexed on nitrogen, in the optimum transition state, confers valuable selectivity to the reaction. It may thus be used as a kinetic probe for stereochemistry as well as for the formation of specific enamine isomers. 

Due to the relatively high acidities of their hydroxy groups, hydroxyazoles readily exchange their protons with metal ions, which leads to stabilization of metal derivatives of the hydroxy tautomeric forms in metal coordination compounds of 2(5)-oxoazoles [97UK434 98AHC(72)1]. A typical example is the mercury complex 361 [93JCS(D)1003]. 

Photoelectron spectra of furyl mercury complexes 26-30 were studied [79JCS(D)2037]. 

Occasionally the histidine-mercury complex settles slowly. In this case the supernatant liquid may be siphoned off and filtered. The small amount of material collected on the filter is then returned to the main portion. 

Other transition metals have received much less attention. Complexes of palladium and 2-amino-phenyl-containing formazans have been reported.397 Mercury complexes of tridentate formazans have been studied.398 Silver complexes of tridentate benzothiazolyl-containing formazans have also been studied.399 Recently, alkali and alkaline earth metals have been the subject of many studies. Formazans such as 228 and 229 as well as the macrocyclic 204 have received considerable attention as metal-specific analytical reagents.400-41 1... 

Bebout DC, Berry SM (2006) Probing Mercury Complex Speciation with Multinuclear NMR 120 81-105... 

Mass spectrometry (MS) in its various forms, and with various procedures for vaporization and ionization, contributes to the identification and characterization of complex species by their isotopomer pattern of the intact ions (usually cation) and by their fragmentation pattern. Upon ionization by the rough electron impact (El) the molecular peak often does not appear, in contrast to the more gentle field desorption (FD) or fast-atom bombardment (FAB) techniques. An even more gentle way is provided by the electrospray (ES) method, which allows all ionic species (optionally cationic or anionic) present in solution to be detected. Descriptions of ESMS and its application to selected problems are published 45-47 also a representative application of this method in a study of phosphine-mercury complexes in solution is reported.48... 

Organic compounds such as terminal alkynes can undergo direct mercuration using various mercury salts. For instance, alkyne 61 has been shown to react with Hg(OAc)2 to form the symmetrical bis-alkyl-mercury complex 62 (Equation (21)).73... 

Longer Hg-7r interactions are observed in the /> ra-/-butylcalix[4]arene mercury complex 162. The mercury atom forms primary bonds with the two sulfur atoms and engages in weaker secondary interactions with two arene rings of the calixarene whose centroids sit at 3.07-3.11 A from the metal center.201... 

Mercury Mercury complexed with ammonium tetra methylene- Chloroform extract analysed by < 5 ng/1 Hg absolute dithiocarbamate, extracted with chloroform graphite tube AAS... 

These reactions are compared with those of the equivalent 1-alkenyl HgCl compounds. Some differences are observed, notably that the mercury complexes will react with PhSe—SePh, while the tin complexes undergo no reaction at all. The reactions with ChHg, QHgCl and RHgCl, however, are broadly similar to that shown in reaction 26. 

The cationic carbene-mercury complex 22 was prepared more than 30 years ago (3) via the reaction of 1,3-diphenylimidazolium perchlorate 5 (R = Ph R = H) with mercuric acetate. The same synthetic approach has been used more recently for the preparation of the analogous l,3-dimethylimidazol-2-ylidene complex, 23 (20). Thus, although 22 possesses a linear carbene-Hg-carbene skeleton (21), that of 23 is distorted toward a tetrahedral arrangement (C(carbene)-Hg-(C(carbene)) = 161.4(3)°) due to interactions with the chloride anions... 

The six equations in the six unknowns xlt x2,..., x6 are the electroneutrality condition, conservation of mercury and chloride components, plus the three mass action laws corresponding to water dissociation and mercury complexation by Cl- and OH-. The condition of electroneutrality reads... 

To circumvent some of the above-mentioned drawbacks of sulfur-based mercury chemodosimeters, a system based on the alkyne oxymercuration of 58 has been developed (Fig. 22) [146]. 58 shows high selectivity, a limit of detection of ca. 8 ppm, resistance against strong oxidants, and a positive reaction even in the presence of cysteine, which is known to form stable mercury complexes and is used for the extraction of mercury from tissue samples. Another metal that is well-known for its catalytic ability is palladium, catalyzing different reactions depending on its oxidation state. Since this metal is toxic, assessment of the maximum allowable concentration of Pd in consumer products such as pharmaceuticals requires highly sensitive and selective detection schemes. For this purpose, indicator 60 was conceived to undergo allylic oxidative insertion to the fluorescein... 

A few mercury complexes featuring diynyl ligands are known. Deprotonation of W =C(NMe2)C=CC=CH (CO)s with BuLi, followed by treatment with HgCl2 has afforded Hg C=CC=CC(NMe2)=W(CO)5 2 and mercury(I) derivatives of more common terminal diynes HC=CC CR (R = Me, Ph) have also been described. ... 

Borovik, A. S. Bott, S. G. Barron, A. R. Arene-Mercury Complexes Stabilized Aluminum and Gallium Chloride Synthesis and Structural Characterization. J. Am. Chem. Soc. 

Kouwenhoven (6) sjmthesised two bis-olefinic ligands related to the simple pent-4-enyl compounds mentioned above. These were of the general formula PhD[(CH2)aCH =CH2]2 (D = P, As) and formed platinum(II) and mercury(II) complexes. The platinum complexes LPtCla (L = PhD[(CH2)3 CH=CH2]2) were found to be monomeric species containing, as shown by their i. r. spectra, one coordinated and one free double bond. The two mercury complexes [LHgClaJs did not contain coordinated olefinic groups. 

Safavi and Gholivand [44] have studied electrochemical reduction of mercury complexes with 2-aminocyclopentene-l-dithiocarboxylic acid (ACD = L) and its selected derivatives at mercury electrodes in DMSO. Reduction of Hg(ACD)2 proceeded in a single 2-e step ... 

Electrochemical synthesis and structural characterization of zinc, cadmium, and mercury complexes of heterocyclic... 

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