Strong Closed-Shell Interactions in Inorganic Chemistry.

Synthesis, structure, and bonding in polyiodide and metal iodide-iodine systems.

Bonding and structure trends of thiosemicarbazone derivatives of metals—An overview

Recent studies suggest that the developmental toxicity associated with childhood lead poisoning may be attributable to interactions of Pb(II) with proteins containing thiol-rich structural zinc-binding sites. Here, we report detailed structural studies of Pb(II) in such sites, providing critical insights into the mechanism by which lead alters the activity of these proteins. X-ray absorption spectroscopy of Pb(II) bound to structural zinc-binding peptides reveals that Pb(II) binds in a three-coordinate Pb(II)-S3 mode, while Zn(II) is known to bind in a four-coordinate mode in these proteins. This Pb(II)-S_3 coordination in peptides is consistent with a trigonal pyramidal Pb(II)-S_3 model compound previously reported by Bridgewater and Parkin, but it differs from many other reports in the small molecule literature which have suggested Pb(II)-S_4 as a preferred coordination mode for lead. Reexamination of the published structures of these “Pb(II)-S_4” compounds reveals that, in almost all cases, the coordination number of Pb is actually 5, 6, or 8. The results reported herein combined with this new review of published structures suggest that lead prefers to avoid four-coordination in sulfur-rich sites, binding instead as trigonal pyramidal Pb(II)-S_3 or as Pb(II)-S_(5-8). In the case of structural zinc-binding protein sites, the observation that lead binds in a three-coordinate mode, and in a geometry that is fundamentally different from the natural coordination of zinc in these sites, explains why lead disrupts the structure of these peptides and thus provides the first detailed molecular understanding of the developmental toxicity of lead.

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Reexamination of lead(II) coordination preferences in sulfur-rich sites: implications for a critical mechanism of lead poisoning.

Bismuth chemistry has received much less attention in comparison with that of N, P, As, and Sb, but the last years have revealed an increasing interest in the investigation of both the inorganic and the organometallic chemistry of the heaviest element of the group 15 elements.1 There are several fields Cristian Silvestru (left) was born in Baia-Mare, Romania, in 1955 and graduated in chemistry at the Babes-Bolyai University, Cluj-Napoca, in 1979. He obtained his M.Sc. degree 1 year later. After 2 years as Chemist in a mining company, he was a Research Chemist at the Institute of Chemical and Biochemical Energetics from 1982 to 1989. He received his Ph.D. degree in the group of Professor Ionel Haiduc in Cluj in 1990, with his dissertation research on organometallic compounds with potential biologic activity. In 1990, he joined the Chemistry Department of the BabesBolyai University in Cluj-Napoca. Since 1995 he has been a Full Professor of Inorganic Chemistry and since 1996 Vice-Dean of the Faculty of Chemistry and Engineering Chemistry. He published a book, Organometallics in Cancer Chemotherapy (with I. Haiduc, 2 volumes, CRC Press: Boca Raton, FL, 1989, 1990), and in 1992 received the “Petre Spacu” award of the Romanian Academy for his contributions on the antitumor properties of organometallic compounds (with Dr. Carmen Socaciu and Dr. Adela Bara). Professor Silvestru spent several research stays in Germany (Bremen University 1993sVisiting Professor, 1996sDAAD Grant), Belgium (Vrije Universiteit Brussel 1993sEuropean Community Grant), and Mexico (Instituto de Quimica, Universidad Nacional Autonoma de Mexico 1993−95sVisiting Research Professor, CONACYT Grant). His research interests include organometallic chemistry of main group elements, coordination chemistry of thioligands (mainly organophosphorus compounds), and biological (antitumor) properties of main group organometallics.

Structural chemistry of bismuth compounds. I. Organobismuth derivatives.

Abstract Reduction of Mes2BiBr with Na in liquid NH3 or with Cp2Co in THF or C6D6 gives Mes4Bi2 (1) as a red solid that reversibly becomes pink on cooling with liquid nitrogen. Oxidation of 1 in air, or reaction of Mes2BiBr with NaOH, gives (Mes2Bi)2O (2). (Mes2Bi)2S (3) and (Mes2Bi)2Se (4) are formed by reaction of Mes2BiBr with Na2S in water or with Na2Se in liquid NH3, respectively. (Mes2Bi)2Te (5) is obtained by reaction of 1 with Te or by reaction of Mes2BiBr with Na2Te. Reactions of Me4Bi2 with Se or Te produce (Me2Bi)2Se (6) and (Me2Bi)2Te (7). With equimolar amounts of p-benzoquinone tetramethyldibismuthane yields 1,4-C6H4(OBiMe2)2 (8). 1H NMR data and mass spectra of 1-8, UV-VIS data of 1-4, and the crystal structures of 2·0,5C2H5OH, 3 and 4 are reported.

Tetramesityldibismutan, Bis(dimesitylbismut)- und Bis(dimethylbismut)chalkogenide / Tetramesityldibismuthane, Bis(dimesitylbismuth)- and Bis(dimethylbismuth)chalcogenides

Strukturen und reaktionen von methylantimondihalogeniden und versuche zur darstellung von methylantimon

Novel Coordination Pattern of Dithiophosphorus Ligands - Crystal and Molecular-Structure of (Diphenylphosphinodithioato)Phenyltellurium(II), Phtes2Pph2 - Supramolecular Association Through Monodentate Biconnective Dithiophosphorus Ligands

Exchange reactions of R3Sb (R = o-Tol, m-Tol, p-Tol) with SbCl3 in a 1:2 molar ratio give RSbCl2. Silylstibanes RSb(SiMe3)2 were obtained by reaction of RSbCl2 and Me3SiCl with Mg in THF. Slow access of air to solutions of RSb(SiMe3)2 afforded orange crystals of the composition (RSb)n. Crystal structures were determined by X-ray crystallography for R = o-Tol and m-Tol as stacks of (RSb)6 rings in the chair conformation with equatorial substituents. In the crystals of (m-TolSb)6 there are short intermolecular Sbb distances of 420 pm. Solutions of (RSb)n (R = Ph, o-Tol, m-Tol, p-Tol) in C6D6 were analyzed by 1H-NMR spectroscopy. They contain (RSb)5 and (RSb)4 in equilibria. Raman spectra of (PhSb)6 or (p-TolSb)n show signals for Sbn at β = 151 or 153 cm-1. 13C-CP-MAS-NMR data of (p-TolSb)n are reported.

Syntheses, Structures, and Equilibria of o‐, m‐, p‐Tolyl‐ and Phenylantimony Rings

New aryltellurium(II) diorganophosphinodithioates. Crystal structure of red (294 K) and yellow (173 K) ∞1[PhTeS (S)PPh2], a supramolecular polymer displaying an unusual coordination pattern of the phosphinodithioato ligand

Klaus H. Ebert

Papers

Tetramesityldibismutan, Bis(dimesitylbismut)- und Bis(dimethylbismut)chalkogenide / Tetramesityldibismuthane, Bis(dimesitylbismuth)- and Bis(dimethylbismuth)chalcogenides

Strukturen und reaktionen von methylantimondihalogeniden und versuche zur darstellung von methylantimon

Novel Coordination Pattern of Dithiophosphorus Ligands - Crystal and Molecular-Structure of (Diphenylphosphinodithioato)Phenyltellurium(II), Phtes2Pph2 - Supramolecular Association Through Monodentate Biconnective Dithiophosphorus Ligands

Syntheses, Structures, and Equilibria of o‐, m‐, p‐Tolyl‐ and Phenylantimony Rings

New aryltellurium(II) diorganophosphinodithioates. Crystal structure of red (294 K) and yellow (173 K) ∞1[PhTeS (S)PPh2], a supramolecular polymer displaying an unusual coordination pattern of the phosphinodithioato ligand