Solution and structural investigations of ligand preorganization in trivalent lanthanide complexes of bicyclic malonamides.

This report describes an investigation into the coordination chemistry of trivalent lanthanides in solution and the solid state with acyclic and preorganized bicyclic malonamide ligands. Two experimental investigations were performed: solution binding affinities were determined through single-phase spectrophotometric titrations and the extent of conformational change upon binding was investigated with single-crystal X-ray crystallography. Both experimental methods compare the bicyclic malonamide (BMA), which is designed to be preorganized for binding trivalent lanthanides, to an analogous acyclic malonamide.

Regioselective formation of beta-alkyl-alpha-phenyliridabenzenes via unsymmetrical 3-vinylcyclopropenes: probing steric and electronic influences by varying the alkyl ring substituent.

The synthesis of unsymmetrical (Z)-1-alkyl-3-(2-iodovinyl)-2-phenyl-1-cyclopropenes (R=Me (8 a), Et (8 b), iPr (8 c), and tBu (8 d)) and their reactions with Vaska's complex [Ir(CO)Cl(PPh3)2] and its trimethylphosphine analogue [Ir(CO)Cl(PMe3)2] were investigated. Iridabenzvalene (13/20), iridabenzene (14/21), and/or eta(5)-cyclopentadienyliridium complexes (15/22) were obtained in modest yields and were fully characterized by spectroscopic means. X-ray structural data was secured for iridabenzvalene 13 d and iridabenzenes 14 a,b,d.

K2[HCr2AsO10]: redetermination of phase II and the predicted structure of phase I.

Our prediction that phase II of dipotassium hydrogen chromatoarsenate, K(2)[HCr(2)AsO(10)], is ferroelectric, based on the analysis of the atomic coordinates by Averbuch-Pouchot, Durif & Guitel [Acta Cryst. (1978), B34, 3725-3727], led to an independent redetermination of the structure using two separate crystals. The resulting improved accuracy allows the inference that the H atom is located in the hydrogen bonds of length 2.

Phase transitions in K2Cr2O7 and structural redeterminations of phase II.

Crystals of phase II K2Cr2O7, potassium dichromate, space group P1 , grown from aqueous solution undergo a first-order transition to phase I, space group reportedly P21/n, at a phase-transition temperature, TPT, of 544 (2) K on first heating; the corresponding transition on cooling is at 502 (2) K. The endotherm on subsequent heatings occurs reproducibly at TPT = 531 (2) K. Mass loss between ca 531 and 544 K, identified as included water, is rapid and continues more slowly to higher temperatures for a total loss of ca 0.

Experimental and theoretical investigation of the coarctate cyclization of (2-Ethynylphenyl)phenyldiazenes.

A new route to substituted 2-phenyl-2H-indazoles through the cyclization of (2-ethynylphenyl)phenyldiazenes is presented. A coarctate reaction pathway forms the isoindazole carbene under neutral conditions, at moderate temperatures, and without the requirement of a carbene stabilizer. A wide variety of previously unknown diazene precursors was synthesized and cyclized.

Disodium chromium(III) hexamolybdoiodate(VII) 24-hydrate, Na(2)Cr[IMo(6)O(24)].24H(2)O.

The title compound can be formulated as [Cr(H(2)O)(6)][Na(2)(H(2)O)(10)][IMo(6)O(24)].8H(2)O. The anion has the I atom on an inversion centre and has close to $\overline 3$m symmetry, with I-O bond lengths in the range 1.

Honeycomb nets with interpenetrating frameworks involving iminodiacetato-copper(II) blocks and bipyridine spacers: syntheses, characterization, and magnetic studies.

Three coordination polymers of copper(II), viz. ([Cu(ida)(4,4'-bipyH)]ClO(4))( proportional, variant ) (1), ([Cu(2)(ida)(2)(micro-4,4'-bipy)].2H(2)O)( proportional, variant ) (2), and [Cu(2)(ida)(2)(bpa)]( proportional, variant ) (3) have been synthesized by the process of self-assembly using Cu(ida) [ida = iminodiacetate(2-)] as the building block and 4,4'-bipyridyl and 1,2-bis(4-pyridyl)ethane (bpa) as linkers.

Radical cage effects in the photochemical degradation of polymers: effect of radical size and mass on the cage recombination efficiency of radical cage pairs generated photochemically from the (CpCH2CH2N(CH3)C(O)(CH2)nCH3)2Mo2(CO)6 (n = 3, 8, 18) complexes.

This study explored the effect of radical size, chain length, and mass on the cage recombination efficiency of photochemically generated radical cage pairs. Radical cage pairs containing long-chain radicals of the type [(CpCH(2)CH(2)N(CH(3))C(O)(CH(2))(n)CH(3))(CO)(3)Mo*, *Mo(CO)(3)(CpCH(2)CH(2)(CH(3))NC(O)(CH(2))(n)CH(3))] were generated in hexanes/squalane solution by photolysis (lambda = 546 nm) of the Mo-Mo bonds in (CpCH(2)CH(2)N(CH(3))C(O)(CH(2))(n)CH(3))(2)Mo(2)(CO)(6) (n = 3, 8, 18). The cage recombination efficiencies (denoted as F(cP), where F(cP) = k(cP)/(k(cP) + k(dP)), k(dP) is the diffusion rate constant, and k(cP) is the radical recombination rate constant) for the radical cage pairs were obtained by extracting them from quantum yield measurements for the photoreactions with CCl(4) (a metal-radical trap) as a function of solvent system viscosity.

Oxovanadium(IV) and -(V) complexes of dithiocarbazate-based tridentate Schiff base ligands: syntheses, structure, and photochemical reactivity of compounds involving imidazole derivatives as coligands.

The tridentate dithiocarbazate-based Schiff base ligands H(2)L (S-methyl-3-((5-R-2-hydroxyphenyl)methyl)dithiocarbazate, R = NO(2), L = L(2); R = Br, L = L(3)) react with [VO(acac)(2)] in the presence of imidazole derivatives as coligands to form oxovanadium(IV) and cis-dioxovanadium(V) complexes. With benzimidazole and N-methylimidazole, the products are oxovanadium(IV) complexes, viz. [VOL(3)(BzIm)].

Precursors to water-soluble dinitrogen carriers. Synthesis of water-soluble complexes of iron(II) containing water-soluble chelating phosphine ligands of the type 1,2-bis(bis(hydroxyalkyl)phosphino)ethane.

The reactions of the water-soluble chelating phosphines 1,2-bis(bis(hydroxyalkyl)phosphino)ethane (alkyl = n-propyl, DHPrPE; n-butyl, DHBuPE; n-pentyl, DHPePE) with FeCl(2).4H(2)O and FeSO(4).7H(2)O were studied as routes to water-soluble complexes that will bind small molecules, dinitrogen in particular.

[2.2]paracyclophane/dehydrobenzoannulene hybrids: transannular delocalization in open-circuited conjugated macrocycles.

Enhanced global delocalization throughout the "stepped" π-electron systems of the [2.2]paracyclophane/dehydrobenzoannulene (PC/DBA) hybrids 1 and 2 is strongly suggested by a comparison of their electronic absorption spectra with those of model compounds with complete and interrupted classical aromatic delocalization. A distinct bathochromic shift (for 1) and greater absorption intensity at higher wavelengths (for 1 and 2) is observed versus the corresponding model hydrocarbons.

Cyclization of 1-(2-alkynylphenyl)-3,3-dialkyltriazenes: a convenient, high-yield synthesis of substituted cinnolines and isoindazoles.

A new route to isoindazoles and cinnolines through the cyclization of (2-alkynylphenyl)triazenes under neutral conditions is presented. The products that result from heating the starting triazenes depend on both the type of alkyne ortho to the triazene functionality and the temperature used. Butadiyne moieties ortho to dialkyltriazenes yield bis-isoindazole dimers when heated to 150 degrees C in MeI.

Deliberate design of ligand architecture yields dramatic enhancement of metal ion affinity.

Evaluation of the malonamide substructure with respect to binding site preorganization and complementarity for lanthanide metal ions suggests a new ligand architecture specifically designed to enhance lanthanide ion affinity. Consideration of conformational reorganization, restricted bond rotation, and donor group orientation suggests that typical malonamide structures, for example, N,N,N'N'-tetrahexylpropane-1,3-diamide (1), N,N'-dibutyl-N,N'-dimethyl-2-tetradecylpropane-1,3-diamide (2), or N,N,N'N'-tetramethylpropane-1,3-diamide (6), are poorly organized for metal ion complexation. Molecular mechanics analyses show that the unfavorable enthalpic and entropic terms are eliminated by the use of the novel bicyclic architecture found in 3,9-diaza-3,9-dimethylbicyclo[4.

Synthesis, characterization, and reactivity of mononuclear O,N-chelated vanadium(IV) and -(III) complexes of methyl 2-Aminocyclopent-1-ene-1-dithiocarboxylate based ligand: reporting an example of conformational isomerism in the solid state.

Vanadium(IV) and -(III) complexes of a tetradentate N(2)OS Schiff base ligand H(2)L [derived from methyl 2-((beta-aminoethyl)amino)cyclopent-1-ene-1-dithiocarboxylate and salicylaldehyde] are reported. In all the complexes, the ligand acts in a bidentate (N,O) fashion leaving a part containing the N,S donor set uncoordinated. The oxovanadium(IV) complex [VO(HL)(2)] (1) is obtained by the reaction between [VO(acac)(2)] and H(2)L.

mu-Bis(diphenylphosphino)methane-P:P'-octacarbonyldimanganese(Mn-Mn) and its toluene hemisolvate.

The Mn-Mn bonds in the two independent molecules of the unsolvated title compound, [Mn(2)(C(25)H(22)P(2))(CO)(8)], (I), are 2.9714 (7) and 2.9746 (7) A.

Hepatitis B.

The management of acute HBV infection is supportive. Specific treatment is not indicated for HBV carriers because they often have no evidence of liver injury, and, further, do not respond to currently available therapies. Interferon monotherapy is best indicated for patients with chronic replicating HBV infection and evidence of chronic hepatitis.

Preparation, X-ray crystal structures, and reactivity of alkynylcyclopropenylium salts.

Several 1,2-diphenyl-3-alkynylcyclopropenes were prepared by the reaction of acetylenic nucleophiles with diphenylcyclopropenylium perchlorate. The cyclopropenes were converted into alkynylcyclopropenylium salts via hydride abstraction with triphenylmethyl cation. Attempts to prepare a dication from either ethyne-bridged or butadiyne-bridged biscyclopropenes produced only the corresponding monocations.

Synthesis, characterization, and isomerization of an iridabenzvalene.

Metal- halogen exchange of vinylcyclopropene 4 followed by addition of [(Me3P)2Ir(CO)Cl] produced iridabenzvalene 5. The metallabenzene valence isomer was characterized by NMR and IR spectroscopy and by X-ray crystallography. Isomerization of complex 5 to iridabenzene derivatives 6 and 13 was accomplished by thermolysis and by Ag+ ions, respectively.

Synthesis and Characterization of Water-Soluble 1,2-Bis(bis(hydroxyalkyl)phosphino)ethane Ligands and Their Nickel(II), Ruthenium(III), and Rhodium(I) Complexes.

The syntheses of the water-soluble, chelating phosphines 1,2-bis(bis(hydroxybutyl)phosphino)ethane (1, n = 3; DHBuPE) and 1,2-bis(bis(hydroxypentyl)phosphino)ethane (1, n = 4; DHPePE) are reported. These ligands (and, in general, other 1,2-bis(bis(hydroxyalkyl)phosphino)ethane ligands) can be used to impart water solubility to metal complexes. As examples of this, the [Ni(DHPrPE)(2)Cl]Cl (2), [Rh(DHPrPE)(2)][Cl] (3), and [Ru(DHBuPE)(2)Cl(2)][Cl] (4) complexes were synthesized; they are indeed soluble in water (>0.

Structure of difluorotriphenylphosphorane.

C18H15F2P, M(r) = 300.29, orthorhombic, Pbcn, a = 6.105 (2), b = 16.

N-adamant-1-yl-N'-(2-iodophenyl)guanidinium chloride.

N-(2-Iodophenyl)-N'-(tricyclo[3.3.1.