Reactions of Hydrosilanes with Transition-Metal Complexes: Formation of Stable Transition-Metal Silyl Compounds.

Mono-, bi-, tetra- and polynuclear copper(II) halogenocarboxylates

The existence of synthetic macrocyclic molecules with hydrophilic cavities containing multiple binding atoms and with hydrophobic exteriors gives rise to extraordinary possibilities with respect to the design and synthesis of molecules with specific cation and anion binding properties. The preparation of many new macrocyclic compounds has recently been reported, but few practical applications for them have been suggested. From the information available, it is becoming clear that it should be possible to synthesize macrocycles that will have specified, or selected, ion binding properties. Cavity size can be varied to accommodate only those cations or anions within a specified narrow band of sizes. Numbers and types of coordinating atoms can be chosen to give essentially electrostatic or covalent bonding or a combination of the two in a metalmacrocycle complex. The metal ligand bond appears to be predominantly ionic in the case of the cyclic polyethers but the covalent character increases on substitution of sulfur or nitrogen for oxygen donor atoms. The essential hydrophobic exteriors of the macrocycles can be modified by the addition of side chains and groups to facilitate the solution of anions and cations in organic solvents. The structures of many macrocycles can be made to approximate naturally occurring molecules, that is, cyclic polyethers similar to macrocyclic antibiotics of the valinomycin and nonactin types and cyclic polyamines similar to porphyrins. Macrocycles are also useful as model compounds for the study of metal interactions with biological systems. The synthetic macrocycles thus represent an intriguing new area of coordination chemistry, the systematic study of which should lead to many interesting and useful chemical applications in the field of metal complexation in solution.

https://science.sciencemag.org/content/sci/174/4008/459.full.pdf

Ion binding by synthetic macrocyclic compounds.

Methods for molecular mechanics modeling of coordination compounds

Chemical speciation governs the biologic behavior of Hg. Because sulfide-producing microoganisms accomplish methylation, Hg speciation in sulfidic habitats is of scientific interest. Here, speciation is determined from solubilities of cinnabar (HgS) only and of cinnabar + sulfur in 0.7 M KCl medium at 298 K over the ranges, pH 1−12, and total dissolved sulfide, 10-3−10-1 M. Without dissolved zero-valent sulfur (S0), solubilities can be explained by the following:  HgS(cinn) + H2S ⇄ Hg(SH)20, pK = 5.36 ± 0.10; HgS(cinn) + SH- ⇄ HgS(SH)-, pK = 5.34 ± 0.30; and HgS(cinn) + 2SH- ⇆ HgS22- + H2S, pK = 7.14 ± 0.16 (all at I = 0.7 M). Unlike ZnS and CdS, HgS solubility is increased by S0, which promotes formation of bidentate polysulfide ligands. Additional Hg solubility in S0 saturated solutions up to pH 9.5 can be explained by:  HgS(cinn) + SH- + (n − 1)S0(rhom) ⇄ Hg(Sn)SH-, pK = 3.97 ± 0.17; n could not be determined but is probably 4−6. In near-neutral, sulfidic natural waters, previously unknown Hg(Sn)SH- mi...

Inorganic Speciation of Mercury in Sulfidic Waters: The Importance of Zero-Valent Sulfur

Preparation and Raman spectra of compounds of the trimercury(2+) cation. Crystal structure of trimercury bis(hexafluoroarsenate(V) Hg3(AsF6)2

Crystal and molecular structure of trifluorosilyltetracarbonylcobalt

Preparation and crystal structure of tetramercury bis(hexafluoroarsenate) Hg4(AsF6)2

Acidopentaminecobalt(III) complexes with polyamine ligands. III. The crystal structure of β-chloro(ethylenediamine)(dipropylenetriamine)cobalt(III) tetrachlorozincate(II)

Acidopentaminecobalt(III) complexes with polyamine ligands. IV. The crystal structure of α-chloro(ethylenediamine)(dipropylenetriamine)cobalt(III) iodide monohydrate and strain energy minimisation calculations for the α- and β-isomeric cations

Peter R. Ireland

Papers

Preparation and Raman spectra of compounds of the trimercury(2+) cation. Crystal structure of trimercury bis(hexafluoroarsenate(V) Hg3(AsF6)2

Crystal and molecular structure of trifluorosilyltetracarbonylcobalt

Preparation and crystal structure of tetramercury bis(hexafluoroarsenate) Hg4(AsF6)2

Acidopentaminecobalt(III) complexes with polyamine ligands. III. The crystal structure of β-chloro(ethylenediamine)(dipropylenetriamine)cobalt(III) tetrachlorozincate(II)

Acidopentaminecobalt(III) complexes with polyamine ligands. IV. The crystal structure of α-chloro(ethylenediamine)(dipropylenetriamine)cobalt(III) iodide monohydrate and strain energy minimisation calculations for the α- and β-isomeric cations