Showing papers in "Coordination Chemistry Reviews in 1990"

Hard and soft acids and bases ― the evolution of a chemical concept

Abstract: The present paper will deal mainly with the more recent developments of the concept of chemical hardness. However, a necessary summary of the early work will be given

The activation of small molecules by dinuclear complexes of copper and other metals

Abstract: Revue synthetique concernant la reactivite de complexes avec des coordinats divers (macrocycles, bases de Schiff, heterocycles azotes), vis a vis de O 2 , CO 2 H 2 O 2 etc... Synthese bibliographique

Complexes of polyaza macrocycles bearing pendent coordinating groups

Abstract: Presentation de travaux relatifs a la reactivite chimique de metaux de transitions vis a vis de macrocycles substitues triaza, tetraaza et pentaaza, ions Co(III) et Ni(II), principalement. Synthese bibliographique

Aromatic nitrogen heterocycles as bridging ligands; a survey

Abstract: Revue synthetique concernant une serie de coordinats bidentes et tridentes, heterocycliques azotes. Synthese bibliographique

The coordination chemistry of platinum anticancer drugs and related compounds with DNA

Abstract: A. Introduction 293 B. Historical interest in Pt-DNA interactions 295 C. Platinum antitumor drugs 295 (i) DNAasthetarget.. 295 (ii) Kinetics of binding to DNA 2% (iii) RegioseIectivity and structures of DNA adducts 296 (iv) Mechanism of action studies. 300 (v) New platinum drugs 303 D. PIatinum compounds as DNA intercaIators 303 (i) The discovery of metaIIointercaIation 303 (ii) Properties of metaIlointercaIators 304 (iii) Structural details 307 (iv) Proof of the neighbor exclusion principle 308 . Linked Pt-intercaIator complexes 309 (i) Tetheredmolecules 309 (ii) Directly Iinked complexes 310 F. Interactions of cis-DDP and intercaIators on DNA 312 G. Summaryandalooktowardsthefuture.. 315 References 317

Quenching of excited states by lanthanide ions and chelates in solution

Abstract: Etude du transfert de charge et energetique entre des ions lanthanides et des composes organiques derives dicetoniques, principalement. Etude du processus et parametre cinetique. Synthese bibliographique

Thermal and light-induced spin crossover in iron(II) complexes

Abstract: Recently, we have discovered a fascinating photophysical effect in spin crossover complexes of iron(II) : Light-Induced Excited Spin State Trapping (LIESST). At sufficiently low temperatures, the low spin state (1A1) can be converted quantitatively to the high spin state (5T2) by irradiating the sample into the 1A1 → 1T1 d-d absorption band (—540 nm). The resulting metastable HS state has a very long lifetime at low temperatures, in some cases it does not decay noticeably over a period of several days at 10 K. Only at temperature above some critical temperature does thermal relaxation back to the LS state set in. The sample can also be reconverted to the LS state by irradiating into the 5T2 → 5E absorption band (∞50 nm). The system thus behaves like an optical switch. The relative positioning - horizontally and vertically - of the potential wells of the two spin states is crucial for the lifetime of the metastable HS state.

Selective air oxidation of light alkanes catalyzed by activated metalloporphyrins - the search for a suprabiotic system

Abstract: Halogenated metalloporphyrins have been examined as catalysts for the air oxidation of propane and isobutane at low temperature. Room temperature oxidation of isobutane with air gives > 13,000 turnovers with > 90% selectivity to tert -butyl alcohol.

Metal compounds in cancer chemotherapy

Abstract: Revue synthetique de complexes metalliques utilisables en chimiotherapeutique. Synthese bibliographique

The role of group 14 element carbene analogues in transition metal chemistry

Abstract: This article is concerned with the role of heavy group 14 element carbene analogues MX 2 , in transition metal (M') chemistry (M=Ge, Sn or Pb; X is a bulky monohapto ligand; X=CHR 2 , NR 2 , OAr or SAr

Soluble selenides and tellurides

Abstract: Caracterisation structurale de complexes metalliques telluro et seleno. Reactivite chimique; synthese bibliographique

The chemistry and solid state properties of nickel, palladium and platinum bis(maleonitriledithiolate) compounds

Abstract: Travaux concernant la reactivite de complexes vis a vis au cours de reactions intramoleculaires, d'echange, d'oxydoreduction. Etudes structurales. Synthese bibliographique

Coordination chemistry of halocarbons

Abstract: Revue synthetique de travaux concernant la reactivite de complexes de metaux divers avec des derives halogenes. Synthese bibliographique jusqu'a mars 1989

Spectroscopy, photophysics and photochemistry of zerovalent transition metal α-diimine complexes

Abstract: Formation de complexes metalliques carbonyles avec des derives de diimine et etude du mecanisme de reactions photochimiques au moyen de plusieurs techniques spectrometriques

Platinum(II) diimine dithiolates. New solution luminescent complexes

Abstract: A series of Pt(diimine)(dithiolate) complexes has been synthesized and characterized spectroscopically. The diimine ligands include 2,2′-bipyridine (bpy), 1,10-phenanthroline (phen), 4,4′-dimethyl-2,2′-bipyridine (dmbpy), 4,4′-diphenyl-2,2′-bipyridine (dpbpy) and 4,7-diphenyl-1,10-phenanthroline (dpphen) while the dithiolates are maleonitriledithiolate (mnt), 2,2-dicyano-1,1-ethylenedithiolate (i-mnt) and ethyl-2-cyano-3,3-dithiolatoacrylate (ecda). The complexes are solvatochromic showing a linear correlation of absorbance with solvent polarity. The most notable feature of the complexes is that they luminesce in fluid solution. The luminescence differs depending on the nature of the dithiolate - mnt complexes show structured emissions while i-mnt and ecda complexes do not - but the emitting state appears to be d-π * (dithiolate) for all complexes. The relative quantum yields for emission have been determined, as have lifetime measurements at 298 K and 77 K in both rigid and fluid media. Quenching studies have been done for Pt(dpphen)(mnt) and Pt(dpphen)(ecda) using dimethylaniline (DMA) as a donor and o-nitrobenzaldehyde (ONB) as an acceptor. Good Stern-Volmer behavior is observed for both reductive and oxidative quenching.

Ambidentate ligands, the schizophrenics of coordination chemistry

Abstract: Representative examples of ambidentate ligand chemistry, drawn primarily from studies published during the past decade, are presented. An overview of the physical methods used for structural elucidation is included, with major emphasis being placed on structures emanating from single crystal X-ray diffraction studies. A great variety of ambidentate ligands are covered, although the bulk of the review deals with the schizophrenic behaviour of the classic ambidentate ligands NO2−CN− NCO−, NCS− NCSe− and NCTe−. As usual, the thiocyanate ion is accorded the most extensive coverage. Other ambidentate ligands discussed include CNO−, CNS−, azaphospholes, aminobenzonitriles, 4,4'-bipyrimidine, cyanoborohydrides, CCO, ClC(CN)3, chloranilate ion, isonitroso(β-ketoimine), nicotinate ion, nitramines, nitrosobenzenes and -anilines, Ph2PC(S)NHR, phosphine/arsine, phosphine sulfide/methine, and phosphinethioamide hybrid ligands, pyridine-2-thione, N-(2-pyridyl)imidazole, 4,6-dimethylpyrimidine, saccharinate ion, H2NSO3−, SO32−, Me2SO, SO2, SO2−, SNO−, NSO−, S2O32−, S2CO2−, SeO32−, SC(O)NHR−, OSNH−, dithioimidodiphosphinate ion, dithiosquarate ion, triphosphate ion, and ureas. Transition metal complexes of ambidentate ligands are emphasized throughout the review.

Coordination chemistry of polychalcogen anions and transition metal carbonyls

Abstract: This article focuses on the chemistry of heavy polychalcogenides as ligands to transition metal centers. After reviewing some of the general synthetic strategies leading to metal polyselenides and polytellurides, work from the author's labs is discussed, which involves the coordination of polychalcogenide anions to metal carbonyls. It has been found that coordination of polychalcogenide anions to metal carbonyls often results in oxidation of the metal center, with loss of some or all of the carbonyl ligands. This oxidative decarbonylation reaction provides a convenient entry to a wide variety of new and existing metal chalcogenide complexes. The scope and potential of this unusual reaction is discussed.

Spectroscopic studies on Cu2Zn2SOD: a continuous advancement of investigation tools

Abstract: Resultats des analyses spectrales effectuees avec diverses techniques spectrometriques dans le but de caracteriser le site actif de complexation de la superoxide dismutase avec les ions Cu 2+ et Zn 2+ . Synthese bibliographique

Infrared spectra of metal β-ketoenolates and related complexes

Abstract: Presentation des frequences IR caracteristiques de complexes metalliques de degre d'oxydation II et de l'uranyle avec des derives cetoniques: tautomerie, substitution de coordinat, formation de compose d'addition. Synthese bibliographique

Complexes of groups 3, 4, the lanthanides and the actinides containing neutral phosphorus donor ligands

Abstract: Revue synthetique de travaux concernant la reactivite de complexes avec des derives du phosphore. Synthese bibliographique

Reactions of alkynes, isocyanides and cyanides at dinitrogen-binding transition metal centres

Abstract: Caracterisation structurale et reactivite de complexe metalliques: reduction chimique, activation des alcynes, protonation et transfert d'hydrogene

Photochemistry of Coordination Compounds of the Main Group Metals

Abstract: A general concept is developed which relates characteristics excited states of main group metal complexes to typical photoreactions. With regard to their electronic spectra and photochemistry the main group metals are classified according to their ground state electron configuration nsxnpy. The photochemistry is generally dominated by the reactivity of metal-centered sp and ligand to metal charge transfer excited states which in most cases initiate inter- and intramolecular photoredox processes.