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Metal-organic frameworks (MOFs) are crystalline synthetic porous materials formed by binding organic linkers to metal nodes: they can be either rigid.sup.1,2 or flexible.sup.3. Zeolites and rigid MOFs have widespread applications in sorption, separation and catalysis that arise from their ability to control the arrangement and chemistry of guest molecules in their pores via the shape and functionality of their internal surface, defined by their chemistry and structure.sup.4,5. Their structures correspond to an energy landscape with a single, albeit highly functional, energy minimum. By contrast, proteins function by navigating between multiple metastable structures using bond rotations of the polypeptide.sup.6,7, where each structure lies in one of the minima of a conformational energy landscape and can be selected according to the chemistry of the molecules that interact with the protein. These structural changes are realized through the mechanisms of conformational selection (where a higher-energy minimum characteristic of the protein is stabilized by small-molecule binding) and induced fit (where a small molecule imposes a structure on the protein that is not a minimum in the absence of that molecule).sup.8. Here we show that rotation about covalent bonds in a peptide linker can change a flexible MOF to afford nine distinct crystal structures, revealing a conformational energy landscape that is characterized by multiple structural minima. The uptake of small-molecule guests by the MOF can be chemically triggered by inducing peptide conformational change. This change transforms the material from a minimum on the landscape that is inactive for guest sorption to an active one. Chemical control of the conformation of a flexible organic linker offers a route to modifying the pore geometry and internal surface chemistry and thus the function of open-framework materials.A new metal-organic framework has several conformational degrees of freedom that can be modified by the external chemical environment to change the structure and trigger the uptake of a guest molecule., Author(s): Alexandros P. Katsoulidis [sup.1] , Dmytro Antypov [sup.1] , George F. S. Whitehead [sup.1] , Elliot J. Carrington [sup.1] , Dave J. Adams [sup.1] [sup.2] , Neil G. Berry [...]

The reaction of the cyclic peroxides cyclobutane malonoyl peroxide and cyclopentane malonoyl peroxide to dimethylplatinum(II) complexes with the bidentate nitrogen donor ligand 4,4'-di-t-butyl-2,2'-bipyridine (bubpy) gave a mixture of the products of cis and trans oxidative addition, [Pt[Me.sub.2]{[([O.sub.2]C).sub.2]C([C.sub.3][H.sub.6])}(bubpy)] and [Pt[Me.sub.2]{[([O.sub.2]C).sub.2]C([C.sub.4][H.sub.8])}(bubpy)], respectively. The cis isomers exist with a chelating dicarboxylate ligand, forming a six-membered ring, while the trans isomers are thought to exist as oligomers, which may react with water or solvent to give complexes containing a monodentate dicarboxylate ligand. Equilibration of the product of cis oxidative addition, cis-[Pt[Me.sub.2]{[([O.sub.2]C).sub.2]C([C.sub.3][H.sub.6])}(bubpy)], with oxalic or phthalic acid to give equilibria with the oxalate cis-[Pt[Me.sub.2]([O.sub.4][C.sub.2])(bubpy)] or phthalate cis-[Pt[Me.sub.2]{[([O.sub.2]C).sub.2][C.sub.6][H.sub.4] }(bubpy)] derivative, respectively, indicated the expected sequence of chelate stability oxalate > cyclobutane malonate > phthalate. Key words: platinum, peroxide, oxidative addition, organometallic. La reaction de peroxydes cycliques, le peroxyde de cyclobutane malonoyle et le peroxyde de cyclopentane malonoyle, avec des complexes de dimethylplatine (II) en presence du 4,4'-di-t-butyl-2,2'-bipyridine (bubpy), ligand bidentate donneur d'azote, a forme un melange de produits d'addition oxydante cis et trans, le [Pt[Me.sub.2]{[([O.sub.2]C).sub.2]C([C.sub.3][H.sub.6])}(bubpy)] et le [Pt[Me.sub.2]{[([O.sub.2]C).sub.2]C([C.sub.4][H.sub.8])}(bubpy)], respectivement. Les complexes avec un ligand dicarboxylate chelatant existent sous forme d'isomeres cis et forment un cycle a six atomes, tandis qu'on croit que les isomeres trans existent sous forme d'oligomeres qui peuvent reagir avec l'eau ou un solvant pour produire des complexes comprenant un ligand dicarboxylate monodentate. L'equilibration du produit d'addition oxydante cis, le cis-[Pt[Me.sub.2]{[([O.sub.2]C).sub.2]C([C.sub.3][H.sub.6])}(bubpy)], avec l'acide oxalique ou phtalique qui se produit pour former respectivement a l'etat d'equilibre les derives cis-[Pt[Me.sub.2]([O.sub.4][C.sub.2])(bubpy)] oxalate ou cis- [Pt[Me.sub.2]{[([O.sub.2]C).sub.2][C.sub.6][H.sub.4]}(bubpy)] phtalate, revele la sequence de stabilite attendue des chelates : oxalate > malonate de cyclobutane > phthalate. [Traduit par la Redaction] Mots-cles : platine, peroxyde, addition oxydante, organometallique., Introduction Platinum metal and platinum complexes both play important roles in oxidation catalysis, especially using molecular oxygen or hydrogen peroxide as oxidants. (1-4) Combining C-H bond activation with oxidation is [...]

Fast time-resolved infrared spectroscopic measurements have allowed precise determination of the rates of activation of alkanes by Cp'Rh(CO) (Cp' = [[eta].sup.5]-[C.sub.5][H.sub.5] or [[eta].sup.5]-[C.sub.5][Me.sub.5]). We have monitored the kinetics of C-H activation in solution at room temperature and determined how the change in rate of oxidative cleavage varies from methane to decane. The lifetime of CpRh(CO)(alkane) shows a nearly linear behavior with respect to the length of the alkane chain, whereas the related Cp*Rh(CO)(alkane) has clear oscillatory behavior upon changing the alkane. Coupled cluster and density functional theory calculations on these complexes, transition states, and intermediates provide the insight into the mechanism and barriers in order to develop a kinetic simulation of the experimental results. The observed behavior is a subtle interplay between the rates of activation and migration. Unexpectedly, the calculations predict that the most rapid process in these Cp'Rh (CO)(alkane) systems is the 1,3-migration along the alkane chain. The linear behavior in the observed lifetime of CpRh(CO)(alkane) results from a mechanism in which the next most rapid process is the activation of primary C-H bonds (-C[H.sub.3] groups), while the third key step in this system is 1,2-migration with a slightly slower rate. The oscillatory behavior in the lifetime of Cp*Rh(CO)(alkane) with respect to the alkane's chain length follows from subtle interplay between more rapid migrations and less rapid primary C-H activation, with respect to CpRh(CO)(alkane), especially when the C[H.sub.3] group is near a gauche turn. This interplay results in the activation being controlled by the percentage of alkane conformers. organometallic | photochemistry | computation | transition metal | sigma complex doi/ 10.1073/pnas.1001249107

A computational investigation about the Lewis acid-base adducts between bases [Cp.sub.2]M[H.sub.2] (M = Mo, W) and acids B[X.sub.3] (X = F, Cl) and [Al([CH.sub.3].sub.3] is presented. Density functional methods based on pure and hybrid correlation-exchange functionals and relativistic corrections based on the zero order relativistic approximation (ZORA) have been applied. A comparison with experimental data has been addressed to give insights about the nature of the acid-base interaction with the aim to evaluate the role of the transition metal in charge donation toward the acid centre. In this respect, the likelihood of proposed criteria for recognizing the presence of transition-metal direct charge donation has been discussed. Key words: metallocenes, Lewis basicity, density functional theory (DFT), atoms in molecules (AIM), zero order relativistic approximation (ZORA). On a effectue une etude theorique des adduits acide-base de Lewis entre les bases [Cp.sub.2]M[H.sub.2] (M = Mo, W) et les acides B[X.sub.3] (X = F, Cl) et [Al([CH.sub.3].sub.3]. On a utilise les methodes de la fonctionnelle de la densite en faisant appel a des fonctionnelles de correlation-echange pures ainsi qu'hybrides et on a applique des corrections relativistes basees sur l'approximation relativiste d'ordre zero (AROZ). Une comparaison avec les donnees experimentales a ete realisee afin d'obtenir des informations sur la nature de l'interaction acide-base qui permettraient d'evaluer le role du metal de transition dans le transfert de charge vers le centre acide. Dans cette optique, on discute du potentiel d'utilite des criteres proposes pour reconnay tre la presence d'un transfert de charge direct de la part du metal de transition. Mots-cles : metallocenes, basicite de Lewis, theorie de la fonctionnelle de la densite (TFD), atomes dans une molecule << AIM >>, approximation relativiste d'ordre zero (AROZ). [Traduit par la Redaction], Introduction The acid-base adduct between bis(cyclopentadienyl)dihydridotungsten ([Cp.sub.2]W[H.sub.2]) and B[F.sub.3] was firstly communicated by Shriver (1) in 1963. It represented one of the first (and representative) examples of Lewis base behaviour [...]

The oxidative addition of alkyl bromides RC[H.sub.2]Br (R = [C.sub.5][H.sub.4]N, [C.sub.6][H.sub.4]CN, C[H.sub.2][C.sub.6][H.sub.4]C[O.sub.2]H, or C[H.sub.2][C.sub.6][H.sub.4]C[H.sub.2]C[O.sub.2]H) to dimethylplatinum(II) complexes [Pt[Me.sub.2](LL)] (LL = diimine ligand) gives the corresponding organoplatinum(IV) complexes [PtBr[Me.sub.2](C[H.sub.2]R)(LL)] containing functionality in the alkyl group RC[H.sub.2]. The pyridyl derivatives can be protonated, while abstraction of the bromide ligand from [PtBr[Me.sub.2](C[H.sub.2]R)(LL)] can form cationic complexes, which can react with water or form oligomers by self-assembly. Key words: platinum, organometallic, hydrogen bond, supramolecular. L'addition oxydante de bromures d'alkyle, RC[H.sub.2]Br [R = [C.sub.5][H.sub.4]N, [C.sub.6][H.sub.4]CN, C[H.sub.2][C.sub.6][H.sub.4]COOH ou C[H.sub.2][C.sub.6][H.sub.4]C[H.sub.2]COOH] sur des complexes de dimethylplatine(II) [Pt[Me.sub.2](LL)] [LL = ligand diimine], conduit a la formation de complexes organoplatine(IV) [PtBr[Me.sub.2](C[H.sub.2]R)(LL)] comportant une fonctionnalite dans le groupe alkyle RC[H.sub.2]. Les derives pyridyles peuvent etre protones alors que l'enlevement du ligand bromure a partir de [PtBr[Me.sub.2](C[H.sub.2]R)(LL)] peut conduire a la formation de complexes cationiques qui peuvent reagir avec de l'eau ou former des oligomeres par autoassemblage. Mots-cles : platine, organometallique, liaison hydrogene, supramoleculaire. [Traduit par la Redaction], Introduction The oxidative addition of small molecules to platinum(II) complexes to form organoplatinum(IV) complexes can be a key step in catalysis, and so this type of reaction has been studied [...]

The preparation and characterization of cationic, dinuclear complexes of the type trans-[Pt[([PPh.sub.3]).sub.2] (σ-[C.sub.6][H.sub.4]NHMe) -μ-L-Pt[([PPh.sub.3].sub.2] (σ-[C.sub.6][H.sub.4]NHMe)][(OTf).sub.2] (L = 4,4'-bipyridine, 4,7-phenanthroline, 4,4'-dipyrazolylmethane, and 1,1?-diphenyl-4,4'-dipyrazolylmethane; OTf = trifluoromethanesulfonate (triflate)) containing two [C.sup.3]-N-methylbenzamide ligands are described. The key structural feature of the cationic complexes is the presence of two convergent amide groups that may allow for charge-assisted, H-bonding interactions in solution with suitable heteroaromatic guest molecules such as nucleobases. Key words: organoplatinum(II) complex, organometallic host, dinuclear complex, N-methylbenzamide. On decrit la preparation et la caracterisation de complexes cationiques dinucleaires du type trans-[Pt[([PPh.sub.3]).sub.2] (σ-[C.sub.6][H.sub.4]NHMe)-μ-L-Pt[([PPh.sub.3].sub.2] (σ-[C.sub.6][H.sub.4]NHMe)][(OTf).sub.2] [L= 4,4?-bipyridine; 4,7-phenanthroline; 4,4?-dipyrazolylmethane; et 1,1'-diphenyl-4,4'-dipyrazolylmethane; OTf = trifluoromethanesulfonate (triflate)] contenant deux ligands [C.sup.3]-N-methylbenzamide. La caracteristique structurale cle des complexes cationiques est la presence de deux groupes amides convergents qui, en solution, peuvent favoriser des interactions de liaisons hydrogenes assistees par des charges avec des molecules hotes heteroaromatiques appropriees, telles des nucleobases. Mots-cles : complexe organique du platine(II), hote organometallique, complexe dinucleaire, N-methylbenzamide. [Traduit par la Redaction], Introduction There is great interest in the study of synthetic receptors for the selective binding of nucleobases (1, 2), owing to their many important functional roles in biological systems, e.g., [...]

Organometallic complexes offer chemistry that is not accessible to purely organic molecules and, hence, potentially new mechanisms of drug action. We show here that the presence of both an iodido ligand and a [sigma]-donor/[pi]-acceptor phenylazopyridine ligand confers remarkable inertness toward ligand substitution on the half-sandwich 'piano-stool' ruthenium arene complexes [[([[eta].sup.6]-arene)Ru(azpy)l].sup.+] (where arene = p-cymene or biphenyl, and azpy = N,N-dimethylphenylor hydroxyphenyl-azopyridine) in aqueous solution. Surprisingly, despite this inertness, these complexes are highly cytotoxic to human ovarian A2780 and human lung A549 cancer cells. Fluorescence-trapping experiments in A549 cells suggest that the cytotoxicity arises from an increase in reactive oxygen species. Redox activity of these azopyridine [Ru.sup.11] complexes was confirmed by electrochemical measurements. The first one-electron reduction step (half-wave potential -0.2 to -0.4 V) is assignable to reduction of the azo group of the ligand. In contrast, the unbound azopyridine ligands are not readily reduced. Intriguingly the ruthenium complex acted as a catalyst in reactions with the tripeptide glutathione ([gamma]-L-Glu-L-Cys-Gly), a strong reducing agent present in cells at millimolar concentrations; millimolar amounts of glutathione were oxidized to glutathione disulfide in the presence of micromolar ruthenium concentrations. A redox cycle involving glutathione attack on the azo bond of coordinated azopyridine is proposed. Such ligand-based redox reactions provide new concepts for the design of catalytic drugs. arenes | cytotoxicity | glutathione | redox reactions | ruthenium complexes

The first aryldiimine NCN-pincer ligated rare earth metal dichlorides are synthesized via transmetalation between 2,6-[(2,6-[C.sub.6][H.sub.3]-[R.sub.2]N[double bond]CH).sub.2]-[C.sub.6][H.sub.3]Li and Ln[Cl.sub.3](THF). The results have helped in improving the catalytic performance of the conventional Ziegler-Natta catalysts for the specific selective polymerization of dienes.

A series of bis(phenoxyketimine)titanium dichloride complexes are prepared and analyzed as catalysts for living, isoselective propylene polymerization upon activation with methylaluminoxane (MAO). Mechanical testing has shown that each of these polymers have exhibited good elastomeric properties.

The photolytic and thermal reactivity of [1]- and [2]-metallocenophanes are analyzed. This has shown that either reversible or irreversible haptotropic rearrangements from [[eta].sup.5]- to [[eta].sup.1]-Cp are seen depending on the degree of strain present.

Three new methods are described for preparing 2-substituted 3-furfurals starting from 3-furfural, 3-bromofuran and 3-vinylfurans. 3-Furyl imines have undergone the addition of organometallic reagents to provide furyl sulfonamides and 2-substituted 3-formyl pyrroles are formed under the oxidative rearrangement conditions.

Ultrahigh vacuum delamination of buried metal/organic interfaces has yielded unperturbed X-ray photoemission spectra and has enabled quantitative analysis of the titanium/organic monolayer interface chemistry. The studies have shown that the formation of titanium oxide is strongly dependent on the deposition rate and chamber pressure.

A series of novel organometallic sandwich molecular wires (SMWs) are constructed with alternating iron atoms and cyclopentadienyl (Cp) rings by using density functional theory (DFT) and nonequilibrium Green's function techniques. The studies have shown that the SMWs are good materials for using in molecular electronics.

[super 19]F NMR is used to show that for [beta]-phosphoglucomutase from Lactococcus lactis, the pH-switch in fluoride coordination is not derived from an Al[F.sub.4.sup.-] moiety converting into Al[F.sub.3]. The studies have shown that at near-physiological ratios of aluminum to magnesium, aluminum can dominate over magnesium in the enzyme-metal fluoride inhibitory transition state analog (TSA) complexes.

The synthesis of chiral biisoquinoline-based tricyclic chiral diaminocarbene ligands (BIQ) and their Pd and Cu complexes is reported. The cyclohexyl-BIQ-copper complex is an efficient catalyst for enantioselective [S.sub.N]2' allylic alkylation with Grignard reagents.

The development of a stepwise [3 + 3] annelation reaction that facilitates access to pyrans from epoxides and its application in the preparation of rhopaloic acid A is described. The procedure involves the addition of an allylmagnesium reagent prepared from methallyl alcohol, and a Pd-catalyzed cyclodehydration reaction.

A peptide-based metal-organic framework (MOF), a metal peptide framework (MPF), constructed from an oligovaline peptide family is described. The MPFs are stable and have some internal porosity, which has made them a promising prototype for the further development of MPFs.

Density functional theory (DFT) is used for assessing the [pi]-acidity and [pi]-basicity of metal-organic trimetallic macromolecular complexes of the type [[M([mu]-L)].sub.3], where M = Cu, Ag, or Au and L = carbeniate, imidazolate, pyridiniate, pyrazolate or triazolate. The results have indicated that the metal-organic macromolecules have shown superior [pi]-acidity and -basicity when compared to their organic counterparts.

The asymmetric synthesis of protected amines through the copper/phosphoramidite-catalyzed addition of organozinc and organoaluminum reagents to N-acylimines is described. Optically active N-formyl-protected amines and enantioselectivities are obtained and partial oxidation of the phosphoramidite ligand to the corresponding phosphoric amide is detected under these reaction conditions.

A unified strategy is described for the high-throughput synthesis of multigram quantities of [[eta].sup.3]-oxopyranyl- and [[eta].sup.3]-oxopyridinylmolybdenum complexes. This strategy has used the oxa- and aza-Achmatowicz reaction for preparing the organometallic enantiomeric scaffolds, in both racemic and high enantiopurity versions.

The fabrication of nonaromatic divalent nickel corroles with benzoate moiety by ring contraction of nickel meso-tetraarylporphyrins is reported. The corroles are found to be reactive molecules that could be acylated, halogenated, nitrated, or deoxygenated under very mild conditions.

Author(s): Douglas A. Reed [1]; Benjamin K. Keitz [1, 2]; Julia Oktawiec [1]; Jarad A. Mason [1]; Tome Runevski [1, 3]; Dianne J. Xiao [1]; Lucy E. Darago [1]; Valentina [...]

The synthesis and structural characterization of a microporous metal-organic framework Co(NDC)[(4,4'-Bipy).sub.0.5].Gx (NDC = 2,6-naphthalenedicarboxylate; bipy = bipyridine; G = guest molecules) is described. The anhydrous metal-organic framework exhibit highly selective sorption behaviors with respect to hydrogen- and nitrogen-gas molecules at different conditions.

The application of 2D- and 3D-quantitative structure activity relationships (QSAR) and database mining as a tool to search ligands from large drug database is described. The process would help to rationalize the catalytic high-activity of a synthetically flexible Ti-N=P ethylene polymerization catalysts system.

The creation and properties of colloidally stable shell-cross-linked cylindrical organometallic block copolymer micelles with adjustable length and swellability is reported. The findings showed that shell cross-linking is a prerequisite for generating ceramic replicas through the pyrolysis of polyisoprene-b-polyferrocenylsilane aggregates.

Single crystal XRD method is used to investigate structural differences between low and high surface area metal-organic framework (MOF)-5. The low surface area of MOF-5 had two different classes of crystals.

Studies were conducted to highlight the ability of palladium(II) to catalyze the oxidative amination of alkenes and illustrate the broad potential utility of organometallic oxidase reactions. The results show that the use of nonbasic nitrogen nucleophiles including sulfonamides, phthalimide, and carbamates are critical for success of these reactions, which help to avoid poisoning of the catalyst in the manner observed for alkyl and arylamines.

Metal--organic frameworks (MOFs) have high surface areas and tailorable molecular properties so they have the potential of being selective adsorbents for preconcentrators. In this paper, IRMOF1 is tested as an adsorbent for preconcentration for the first time using dimethyl methylphosphonate (DMMP) as a test case. We find that DMMP is selectively adsorbed on IRMOF1 and is released upon heating to 250[degrees]C. Concentration gains of more than 5000 are observed for DMMP with a 4-s sampling time. Sorption capacities are 0.95 g of DMMP/g of IRMOF1. By comparison, dodecane shows a preconcentration gain of ~5 under similar conditions. These results demonstrate that MOFs can be quite useful in selective preconcentrators.

A study used two organometallic compounds containing zinc and manganese in different ratios as single-source precursors for the synthesis of various new, bimetallic oxide materials with nanoscaled dimensions. The materials synthesis can be performed in the solid, liquid, and gas phases, and the molecular composition of the precursors determines the composition of the resulting materials.

A Ni(meso-daco) [where mese-daco= mercaptoethyl)(sulfinatoethyl)diazacyclooctane] (Ni-2) complex of W[(CO).sub.5] was isolated to compare its donor ability to the analogous ([[nu].sup.1]-Ni-1)W[(CO).sub.5] adduct (where Ni-1 is Ni(bme-daco) and (bme-daco)=bis(mercaptoethyl)-diazacycloethyl)sulfinatoethyl)diazacyclooctane]. It was shown that modification of the thiolate S to sulfinate could serve as a block to bidentate coordination that prevails in the nickel dithiolato complexes without significantly altering the monodentate ligation and donor ability of such metalloligands.

A simple, efficient and broadly applicable general method for the preparation of alkyl, unsaturated, (hetero)aryl, and N-protected [alpha]-amino ketones was developed by acylation of the corresponding N-acylbenzotriazoles with Grignard and heteroaryllithium reagents. The method used accessible acylating agents without any requirement of additional transition metal catalysts or organic ligands to obtain excellent yields of ketones.

An efficient acyclic stereocontrol in tandem 1,4-addition-aldol reactions triggered by catalytic asymmetric organometallic addition is reported. The versatility and efficiency of this methodology are shown in the first catalytic asymmetric synthesis of (-)-phaseolinic acid with 54% overall yield through a short and concise route.

Study is conducted to show that by using a simple MAS scheme for the constant-time (CT) acquisition of proton signal, a significant improvement in resolution can be observed in the NMR spectra of surface organometallic catalyst precursors. It is found that in the complex [syn-(SiO)Mo(=NAr)(=CH[super t]Bu)-(CH2[super t]Bu)], this approach allowed for the unambiquous observation and assignment of the methylene protons.

A study synthezised and characterized a metal-organic framework (MOF) based on Pt, Y, and 2,2'-bipyridine-5,5'-dicarboxylate (BPDC), stable up to 400 degree Celsius. The results reveal that the as-synthesized material would not suffer a permanent loss in porosity upon solvent removal.

The benzene-Ru(II)-supported dilacunary decatungstosilicate [{Ru(C6H6)(H2O)}{RU(C6H6)}(gamma-SiW10(O36)).sup.4-] (1)and the isostructural decatungstogermanate [{Ru(C5H5)(H2O)}{RU(C6H6)}(gamma-SiW10(O36)).sup.4-] (2) are synthesized and characterized by multinuclear solution NMR, IR, elemental analysis, and electrochemistry. A ligand substitution reaction was observed upon addition of dimethyl sulfoxide (dmso) to 1,2, or [Ru(C6H6)Cl2.sub.2], which facilitates substantially the oxidation of the Ru center.

A modular approach that involves selective polymer modification reactions with organometallic reagents was employed to prepare a new class of highly fluorescent triarylborane polymers from trimethylsilyl-substituted polystyrene. The photophysical properties of the new class of polymers indicated electronic communication between the chromophores attached to polysterene, which were exploited for the efficient probing of fluoride and cyanide in the micromolar concentration range.

The influence of molecular geometry, type of exchange-correlation functional, and contraction scheme of basis set applied at the iron nuclei in the calculation of [super.57.Fe] Mossbauer isomer shifts and quadrupole splittings for a wide range of ligand types in inorganic and organometallic systems is studied. Results suggest the use of only pure exchange-correlation functionals for accurate prediction Mossbauer spectra parameters in ferrocenes.

A robust metal-organic framework material [Zn(L)] based on Zn(II) bound to tetraanion of 4,4'-bipyridine-2,6,2',6'-tetracarboxylic acid is reported. The resulting material has a highly established framework structure and reversibly and selectively absorbs organic molecules, [H.sub.2], and methane into the framework pores.

The synthesis and structure of three novel coordination polymers are explored by using hydrothermal methods. The samples are characterized by using a variety of techniques and all the compounds have appeared to be active for the photocatalytic decomposition of common organic dyes used in textile industries.

The potential of tetrazolate-based ligands for forming metal-organic frameworks of utility in hydrogen storage is demonstrated with the use of 1,4-benzeneditetrazolate (BDT.sup.2-) to generate a series of robust, microporous materials. It is shown that the method for desolvating such compounds could dramatically influence the ensuing gas sorption properties.

The synthesis of Ni[N.sub.2][S.sub.2] metalloligands, including the solid-phase synthesis of resin-bound Ni[(CGC).sup.2-], and sulfur-based derivatization with W[(CO).sub.5] and Rh[(CO).sub.2.sup.+] are carried out and described. Through comparison to analogous well characterized, solution-phase complexes, Attenuated Total Reflectance FTIR spectroscopy establishes the presence of unique heterobimetalic complexes both in solution and immobilized on resin beads.

One-electron oxidation of selenomethionine (SeM), selenocystine (SeCys), methyl selenocysteine (MeSeCys) and selenourea (SeU) in aqueous solutions are examined with pulse radiolysis coupled with absorption detection. The bimolecular rate constants are found to be in the range of 2 x 10(super 9) to 10 x 10(super 9) M(super-1)S(super-1).

Hexasubstitution of apical triflate ligands in the octahedral clusters [M](sub 2) [Mo(sub 6X(sub 8)(CF(sub 3)SO(sub 3)(sub 6)] (M=n-Bu(sub 4)N or Cs, X=Br or I) and monosubstitution in [n-Bu(sub 4)N](sub 2)Mo(sub 6)Br(sub 13)(CF(sub 3)SO (sub 3)] was carried out in tetrahydrofuran with simple pyridines and then extended to organometallic pyridines. The organometallic pyridines yielded cluster-cored stars, and dendronic polyallyl and polyferrocenylpyridiens yielded cluster-coated polyallyl and polyferrocenyl dendrimers and dendrons.

The utility of (-)-sparteine-mediated directed ortho metalation (DoM) has been investigated in stereoselective preparation of planar chiral ferrocenes derived from 1,1'-N,N,N',N'-tetraisopropylferrocenedicarboxamide (5). In the synthesis of [C.sub.2]-symmetric analogs of 5, the protocol (base, solvent, and two-step DoM) was found to be crucial for obtaining high enantio- and diastereo-selectivities of the products. A variety of highly enantioenriched mono and doubly functionalized derivatives of 5 have been synthesized. The synthetic applications of these compounds as chiral ligands in asymmetric alkylation of aldehydes and asymmetric palladium-catalyzed allylic substitutions have been demonstrated. Key words: directed ortho metalation, stereoselective deprotonation, ferrocene ligands, asymmetric catalysis. On a etudie l'utilite de l'ortho metallation dirigee (oMD) orientee par la (-)-sparteine, dans la preparation stereoselective de ferrocenes chiraux planaires derives du 1,1'-N,N,N',N'-tetraisopropylferrocenedicarboxamide (5). Dans la synthese d'analogues de symetrie [C.sub.2] du compose 5, on a trouve que le protocole experimental (base, solvant et oMD en deux etapes) est crucial si on veut obtenir des valeurs elevees d'enantio- et de diastereo-selectivites des produits. On a pu synthetiser avec un degre d'enantioenrichissement eleve une grande variete de derives du compose 5 mono- et di-fonctionnalises avec un degre d'enantioenrichissement eleve. On a demontre l'utilite synthetique de ces composes, en particulier comme ligands chiraux dans l'alkylation asymetrique d'aldehydes et dans les substitutions allyliques asymetriques catalysees par le palladiium. Mots cles : ortho metallation dirigee, deprotonation stereoselective, ligands ferrocenes, catalyse asymetrique. [Traduit par la Redaction], The disclosure, with an interesting socio-chemical history, of the correct structure of ferrocene over half a century ago constituted a landmark achievement that heralded an entirely new theme of organometallic [...]

The effect of altering the terminal functional group on self-assembled monolayers (including -OH, -NH2, -SH, and -NH(CH3)) is investigated using density functional theory and MP2 perturbation theory. The results suggest a precursor-mediated deposition for both surfaces, verified by kinetic calculations at low deposition pressures.