Showing papers in "Inorganic Chemistry in 1988"

Absolute Electronegativity and Hardness: Application to Inorganic Chemistry

Abstract: The recent concepts of absolute electronegativity, {chi}, and absolute hardness, {eta}, are briefly reviewed. Experimental values for a large number of molecules and radicals are presented. The values are shown to be in good agreement with the known chemical behavior, both as to nucleophilic-electrophilic properties and as to rates of reaction. Applications are also given for the use of empirical rank orders of the local hardness, {bar {eta}}. The uses of {chi} and {eta} are consistent with frontier orbital theory. To make meaningful comparisons in a series of molecules, it is necessary that these orbitals remain the same. Also it is necessary that the observed I and A values of the molecules relate to the appropriate frontier orbitals. 39 refs., 10 tabs.

Synthesis of isopolymetalate-pillared hydrotalcite via organic-anion-pillared precursors

Abstract: Preparation de l'hydrotalcite Mg 4 Al 2 (OH) 12 (TA)•xH 2 O ou TA est le terephtalate. Insertion de molybdates ou de vanadates par reaction d'echange avec la terephtalate pour aboutir aux composes Mg 12 Al 6 (OH) 36 (Mo 7 O 24 )•xH 2 O et Mg 12 Al 6 (OH) 36 (V 10 O 28 )•xH 2 O. Etude au moyen de la microscopie electronique

Synthetic routes to new polypyridyl complexes of osmium(II)

Abstract: New luminescent complexes of Os(II) that contain either 2,2{prime}-bipyridine (bpy) or 1,10-phenanthroline (phen) as the chromophorib acceptor ligand have been prepared by a combination of established and new synthetic methods. Extensive use of Os(IV) and Os(III) precursors, e.g., Os{sup IV}(bpy)Cl{sub 4} and mer-Os{sup III}(PMe{sub 2}Ph){sub 3}Cl{sub 3} has led to the preparation of materials with ancillary ligands such as tertiary phosphines as preparative intermediates, including Os{sup III}(bpy)(PMe{sub 2}Ph)Cl{sub 3} and cis-Os{sup II}(phen)(diphosphine)Cl{sub 2}. Further substitution of chloro ligands into complexes such as these results in the formation of emissive complexes of Os(II). Another new synthetic route utilizes the versatile Os(II) precursor Os(bpy){sub 2}CO{sub 3}, which allows the facile preparation of dicationic, disubstituted species such as (Os(bpy){sub 2}(norbornadiene)){sup 2+}. Another general procedure, based on the control of solvent and temperature in the substitution chemistry of cis-Os(bpy){sub 2}Cl{sub 2}, has been further developed to produce a variety of new complexes of the types cis-(Os(bpy){sub 2}(L)Cl){sup +} and cis(Os(bpy){sub 2}(L){sub 2}){sup 2+}, where L is a phosphine, arsine, nitrogen, or olefin donor ligand. In a few cases, phosphine entering groups cause the cis geometry to be unfavorable and new trans-(Os(bpy){sub 2}(L){sub 2}){sup 2+} complexes have also been isolated. The resultant complexes comprise themore » largest family of transition-metal-based excited-state reagents with tunable photophysical and redox properties available. When possible, the new complexes have been characterized by UV-visible spectroscopy, emission spectroscopy, cyclic voltammetry, and {sup 31}P and/or {sup 1}H NMR spectroscopy.« less

Synthesis, structure, electrochemistry, and photophysics of methyl-substituted phenylpyridine ortho-metalated iridium(III) complexes

Abstract: Synthetic, structural, photophysical, and electrochemical characterizations of ortho-metalated (Ir(NC)/sub 2/Cl)/sub 2/ dimeric and (Ir(NC)/sub 2/NN)Cl monomeric complexes, where NC = 2(p-tolyl)pyridine (ptpy) or 3-methyl-2-phenylpyridine (mppy) and NN = 2,2'-bipyridine (bpy) are described. Structural characterizations by /sup 1/H and /sup 13/C nuclear magnetic resonance (NMR) indicate the presence of symmetry elements in these complexes. The ultraviolet-visible absorption properties of these complexes are reported. The results of voltametric measurements of these complexes are included. 55 references, 10 figures, 6 tables.

cis- and trans-dihalotetrakis(dimethyl sulfoxide)ruthenium(II) complexes (RuX2(DMSO)4; X=Cl, Br): synthesis, structure, and antitumor activity

Abstract: The chemistry of halogen-dimethyl sulfoxide-ruthenium(II) complexes with the general formula RuX/sub 2/(DMSO)/sub 4/ (X = Cl, Br) is reported. In particular the synthesis and x-ray structure of trans-RuCl/sub 2/(DMSO)/sub 4/ are described and compared with those of the already known cis-RuCl/sub 2/(DMSO)/sub 4/ and trans-RuBr/sub 2/(DMSO)/sub 4/. The structure op a new crystal form of cis-RuCl/sub 2/(DMSO)/sub 4/ is also reported. While the cis isomers are thermodynamically more stable and form from the trans species a photochemically driven cis to trans isomerization reaction is observed in dimethyl sulfoxide solution. Kinetic parameters for the thermal trans to cis isomerization reactions for trans-RuCl/sub 2/(DMSO)/sub 4/ and trans-RuBr/sub 2/(DMSO)/sub 4/ are reported. In chloroform solution the complexes, and in particular the trans isomers, tend to release a dimethyl sulfoxide molecule to give pentacoordinated Ru(II) complexes. However, in aqueous solution, while the cis complexes immediately release one DMSO, the trans ones release two. In both cases, this step is followed by the slow dissociation of a halide ion. For the chloro derivatives the dissociation is completely inhibited at physiological chloride concentrations. Preliminary results from pharmacological tests show that trans-RuCl/sub 2/(CMSO)/sub 4/ is more active than the cis isomer against Lewis lung carcinoma, a metastasizingmore » murine tumor. A remarkable dependence of activity on the halogen nature (Cl > Br) is also observed. 33 refs., 4 figs., 9 tabs.« less

The anomeric effect with central atoms other than carbon. 2. Strong interactions between nonbonded substituents in mono- and polyfluorinated first- and second-row amines, FnAHmNH2

Abstract: Structure des conformeres d'amines mono- et polyfluorees de type F n AH m NH 2 (A=Be, B, C, N, O, Mg, Al, Si, P, S)

Electrocatalytic reduction of carbon dioxide by 2,2'-bipyridine complexes of rhodium and iridium

Abstract: Preparation des complexes cis-[M(bpy) 2 (TFMS) 2 ] + ou M est le rhodium ou l'iridium, bpy est la bipyridine, TFMS est le trifluoromethanesulfonate. Etude de l'activite catalytique de ces complexes au cours de la reduction du CO 2 par voie electrochimique

Metal ion coordinating properties of pyrimidine-nucleoside 5'-monophosphates (CMP, UMP, TMP) and of simple phosphate monoesters, including D-ribose 5'-monophosphate. Establishment of relations between complex stability and phosphate basicity

Abstract: Constantes de stabilite des complexes 1:1, determinees par titrage potentiometrique en solution aqueuse. Modes de liaison

Observations on the composition of Prussian blue films and their electrochemistry

Abstract: Prussian blue (PB) films grown on Pt and SnO2 electrodes are investigated by cyclic voltammetry, energy dispersive X-ray analysis (EDX), XPS, ferric equivalent weight determination, and spectroelectrochemistry.

Vanadium-51 shielding in vanadium(V) complexes: a reference scale for vanadium binding sites in biomolecules

Abstract: NMR data have been employed in the development of an explanation of the interaction of vanadium(V) and large biomolecules such as ribonuclease, transferrin, and peroxidase from A. nodosum. Reported herein is a referencing scale for /sup 51/V chemical shifts, /delta/(/sup 51/V), which incorporates all presently available chemical shift data on V/sup +5/ compounds background theory. A rationalization for the observed shielding trends of the vanadium compounds is presented. 26 refs., 3 figs., 3 tabs.

Structure and magnetic properties of ferrimagnetic chains formed by manganese(II) and nitronyl nitroxides

Abstract: C 20 H 21 MnH 2 O 6 F 12 cristallise dans le systeme monoclinique, groupe d'espace P2 1 /c et sa structure est affinee jusqu'a R=0,054

Equilibrium and structural studies of silicon(IV) and aluminum(III) in aqueous solution. 17. Stable and metastable complexes in the system hydrogen (+)-aluminum(3+)-citric acid

Abstract: Cinetique de complexation de l'acide citrique avec Al 3+ . Formation de Al(H −1 Cit) − et Al(OH)(H −1 Cit) 2− dans les solutions fraichement preparees. Dans les solutions de pH 7 a 9,5, formation de Al 3 (OH) 4 (H −1 Cit) 3 4−

Synthesis and spectroscopic and electrochemical properties of mononuclear and dinuclear bis(2,2'-bipyridyl)ruthenium complexes containing 3,5-bis(pyridin-2-yl)-1,2,4-triazole

Abstract: Preparation, spectres RMN et proprietes electrochimiques de [Ru(bpy)2(bpt)] + et [(Ru(bpy) 2 ) 2 (bpt)] 3+

Silicon-29 NMR studies of aqueous silicate solutions. 1. Chemical shifts and equilibria

Abstract: In the /sup 29/Si NMR spectra of aqueous alkali-metal (M) silicate solutions ((MOH):(Si/sup IV/) = 1.0 or higher), variations in solution composition cause displacements of the peaks of up to 1 ppm largely through interaction of silicate units with M/sup +/. The analysis of the chemical shift data provides a means of predicting /sup 29/Si resonance frequencies for new silicate species and has aided in the identification of the Si/sub 4/O/sub 10//sup 4/minus// (Q/sub 4//sup 3/) anion, in which the Si atoms are at the corners of a regular tetrahedron. A quantitative study of the dependence of silicate connectivity upon temperature (-5 to +144 /degree/C) and solution composition shows that silicate polymerization is favored by low temperature, low alkalinity, and high (Si/sup IV/). In no case could silicate centers with 4-fold connectivity (Q/sup 4/) be detected. The effect of M/sup +/ on the distributions of silica species is small, but the larger M/sup +/ atoms do preferentially stabilize the more highly polymerized silicate anions. 35 refs., 8 figs., 3 tabs.