The Coordination Chemistry of the Mercuric Halides

Dean, Philip A. W.

doi:10.1002/9780470166253.ch3

Cited by 78 publications

References 204 publications

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Mercury: Inorganic & Coordination ChemistryBased in part on the article Mercury: Inorganic & Coordination Chemistry by Gregory J. Grant which appeared in the Encyclopedia of Inorganic Chemistry, First Edition .

Bebout

2005

Encyclopedia of Inorganic Chemistry

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Mercury is one of the oldest known elements. The element exhibits surprisingly different chemistry from its congeners zinc and cadmium, and it is the only group 12 member without a known beneficial biological role. Unique properties associated with the element and its compounds have led to diverse applications. However, many of these are being phased out to minimize further increases in the environmental and atmospheric burden with this toxic heavy metal. Motivations to study the compounds and complexes of mercury include potential for discovery of novel properties such as high‐temperature superconductivity and improved understanding of its interactions in physiological systems. Valuable characterization of mercury‐containing compounds is possible with 199 Hg NMR techniques. Mercury is the only group 12 member to have a stable monovalent state. Observed primarily in the oldest known and most common of all metal polycations, Hg 2 2+ , this metal–metal bonded species readily disproportionates into Hg 2+ and Hg 0 . Mercury(I) compounds, typically, have a linear structure of type XHgHgX. Halides, oxy salts, oxides, and coordination compounds with oxygen and weakly basic nitrogen‐donor ligands are best known for Hg 2 2+ . The most prevalent ionization state of mercury, Hg 2+ , is a d 10 metal ion, which lacks strong coordination number and geometry preferences. As a result, structural characterization of its compounds by X‐ray crystallography is particularly critical. A wide range of halides, pseudohalides, and chalcogenides of Hg 2+ are known. The softness of Hg 2+ has led to an investigation of coordination, with a wide variety of sulfur ligands and physiological sulfur donors being assumed to be the most important. Mercury(II) typically has a stronger affinity for S‐, N‐, and P‐donors than any other divalent metal ion. However, Hg 2+ also has a tendency to undergo incredibly rapid ligand exchange. Recent studies have shown that sterically demanding multidentate ligand systems can suppress ligand exchange processes.

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Mercury: Inorganic & Coordination ChemistryBased in part on the article Mercury: Inorganic & Coordination Chemistry by Gregory J. Grant which appeared in the Encyclopedia of Inorganic Chemistry, First Edition .

Bebout

2005

Encyclopedia of Inorganic Chemistry

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Mercury(II) Complexes with Heterocyclic Thiones − Preparation and Characterization of the 1:1 and 1:2 Mercury(II) Complexes with Benzo-1,3-imidazole-2-thione

Popović

Soldin

Matković‐Čalogović

et al. 2002

Eur. J. Inorg. Chem.

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A series of complexes HgX2(bzimtH2) and HgX2(bzimtH2)2 (X = Cl−, Br−, I−, SCN−; bzimtH2 = benzo‐1,3‐imidazole‐2‐thione) was obtained by reaction of the mercury(II) salts with benzo‐1,3‐imidazole‐2‐thione in the appropriate molar ratio (1:1 or 1:2). Hg(bzimtH)2 was obtained by the deprotonation of bzimtH2 with mercury(II) acetate (irrespective of the molar ratio of the reactants). The complexes were characterised by chemical and thermal analysis, IR, 1H, and 13C NMR spectroscopy, and some [HgX2(bzimtH2), X = I− and HgX2(bzimtH2)2, X = I− and SCN−] by X‐ray single crystal diffractometry. 1H and 13C NMR spectroscopic measurements in dimethyl sulphoxide revealed that the sulphur atom is coordinated to the mercury centre. The greatest complexation effects on the chemical shifts were observed for the thione carbon atom and thioamide proton. The crystal structures of HgI2(bzimtH2)2 and Hg(SCN)2(bzimtH2)2·C2H5OH consist of discrete monomeric molecules with halide or pseudohalide donor atoms and thione sulphur atoms tetrahedrally coordinated to the mercury atom. The structure of HgI2(bzimtH2) is polymeric with a trigonal bipyramidal 3 + 2 coordination geometry around the mercury atom. Polymerisation occurs through Hg···I interactions with neighbouring molecules. The distribution of the π‐electron density in bzimtH2 corresponds to the thioketo tautomeric form in the solid state, and also in the DMSO solution of the complexes. Intermolecular hydrogen bonds of the type N−H···N, N−H···S and N−H···I are observed.

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Mixed-Valence Thallium(I, III) Bromides The Crystal Structure of α—Tl2Br3

Ackermann

Hirschle

Rotter

et al. 2002

Z. anorg. allg. Chem.

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Thallium sesquibromide Tl 2 Br 3 is dimorphic. Scarlet coloured crystals of α-Tl 2 Br 3 were obtained by reactions of aqueous solutions of TlBr 3 and Tl 2 SO 4 in agarose gel. In case of rapid crystallisation of hydrous TlBr 3 /TlBr solutions and from TlBr/TlBr 2 melts ß-Tl 2 Br 3 is formed as scarlet coloured, extremely thin lamellae. The crystal structures of both forms are very similar and can be described as mixed-valence thallium(I)-hexabromothallates(III) Tl 3 [TlBr 6 ]. In the monoclinic unit cell of α-Tl 3 [TlBr 6 ] (a ϭ 26.763(7) Å ; b ϭ 15.311(6) Å ; c ϭ 27.375(6) Å ; ß ϭ 108.63(2)°, Z ϭ 32, space gr. C2/c) the 32 Tl III -cations are found in strongly distorted octahedral TlBr 6 groups. The 96 Tl I cations are surrounded either by four or six TlBr 6 groups with contacts to 8 or 9 Br neighbors. Crystals of ß-Tl 3 [TlBr 6 ] by contrast show almost hexagonal metrics Gemischtvalente Thallium(I,III)-bromide. Die Kristallstruktur von α-Tl 2 Br 3InhaltsübersichtThalliumsesquibromid Tl 2 Br 3 ist dimorph. Dunkelrote Kristallblättchen von α-Tl 2 Br 3 wurden durch Umsetzungen von wässrigen Tl 2 SO 4 /TlBr 3 -Lösungen in Agarose-Gel erhalten. β-Tl 2 Br 3 entsteht in Form extrem dünner, roter Lamellen bei raschen Kristallisationen aus wässrigen TlBr/TlBr 3 -Lösungen oder TlBr/ TlBr 2 -Schmelzen. Beide Formen besitzen einen ähnlichen Aufbau; sie sind als gemischtvalente Thallium(I)-hexabromothallate(III) Tl 3 [TlBr 6 ] zu beschreiben. In der monoklinen Elementarzelle von α-Tl 2 Br 3 (a ϭ 26,763(7) Å ; b ϭ 15,311(6) Å ; c ϭ 27,375(6) Å ; β ϭ 108,63(2)°, Z ϭ 32, Raumgruppe C2/c) sind 32 Tl III -Kationen in stark verzerrten, oktaedrischen TlBr 6 -Baugruppen enthalten. Die 96 Tl I -Kationen sind von vier oder sechs TlBr 6 -Baugruppen umgeben und bilden Kontakte zu 8 oder 9 Br-Nachbarn aus. 2675(a ϭ 13.124(4) Å , b ϭ 13.130(4) Å , c ϭ 25.550(7) Å , γ ϭ 119.91(9)°, Z ϭ 12, P2 1 /m). Refinements of the parameters revealed structural disorder of TlBr 6 units, possibly resulting from multiple twinning. Both structures are composed of Tl 2 [TlBr 6 ] Ϫ and Tl 4 [TlBr 6 ] ϩ multilayers, which alternate parallel (001). The structural relationships of the complicated structures of α-and ß-Tl 3 [TlBr 6 ] to the three polymorphous forms of Tl 2 Cl 3 as well as to the structures of monoclinic hexachlorothallates M 3 TlCl 6 (M ϭ K,Rb) and the cubic elpasolites are discussed.

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The Coordination Chemistry of the Mercuric Halides

Cited by 78 publications

References 204 publications

Mercury: Inorganic & Coordination ChemistryBased in part on the article Mercury: Inorganic & Coordination Chemistry by Gregory J. Grant which appeared in the Encyclopedia of Inorganic Chemistry, First Edition .

Mercury: Inorganic & Coordination ChemistryBased in part on the article Mercury: Inorganic & Coordination Chemistry by Gregory J. Grant which appeared in the Encyclopedia of Inorganic Chemistry, First Edition .

Mercury(II) Complexes with Heterocyclic Thiones − Preparation and Characterization of the 1:1 and 1:2 Mercury(II) Complexes with Benzo-1,3-imidazole-2-thione

Mixed-Valence Thallium(I, III) Bromides The Crystal Structure of α—Tl2Br3

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