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We analyze schemes of high-fidelity multi-qubit CNOT N and C 2 NOT 2 gates for alkali metal neutral atoms used as qubits. These schemes are based on the electromagnetically induced transparency and Rydberg blockade. The fidelity of homonuclear multi-qubit CNOT N gate based on Rydberg blockade was limited by the undesirable interaction between the target atoms and by the coupling laser intensity. We propose overcoming these limits by using strong heteronuclear dipole–dipole interactions via Förster resonances for control and target atoms, while the target atoms are coupled by a weaker van der Waals interaction. We optimized the gate performance in order to achieve higher fidelity, while keeping the coupling laser intensity as small as possible in order to improve the experimental feasibility of the gate schemes. We also considered the optimization of the schemes of the C 2 NOT 2 gates, where the fidelity is affected by the relation between the control–control, control–target and target–target interaction energies. Our numeric simulations confirm that the fidelity of the CNOT 4 gate (single control and four target atoms) can be up to 99.3% and the fidelity of the C 2 NOT 2 (two control and two target atoms) is up to 99.7% for the conditions which are experimentally feasible. [ABSTRACT FROM AUTHOR]

We analyze schemes of high-fidelity multi-qubit CNOTN and C2NOT2 gates for alkali metal neutral atoms used as qubits. These schemes are based on the electromagnetically induced transparency and Rydberg blockade. The fidelity of homonuclear multi-qubit CNOTN gate based on Rydberg blockade was limited by the undesirable interaction between the target atoms and by the coupling laser intensity. We propose overcoming these limits by using strong heteronuclear dipole–dipole interactions via Förster resonances for control and target atoms, while the target atoms are coupled by a weaker van der Waals interaction. We optimized the gate performance in order to achieve higher fidelity, while keeping the coupling laser intensity as small as possible in order to improve the experimental feasibility of the gate schemes. We also considered the optimization of the schemes of the C2NOT2 gates, where the fidelity is affected by the relation between the control–control, control–target and target–target interaction energies. Our numeric simulations confirm that the fidelity of the CNOT4 gate (single control and four target atoms) can be up to 99.3% and the fidelity of the C2NOT2 (two control and two target atoms) is up to 99.7% for the conditions which are experimentally feasible.

Dental research often uses bovine teeth as a substitute for human teeth. The aim of this study was to evaluate differences in the crystalline nanostructures of enamel and dentin between bovine and human teeth, using X-ray diffraction (XRD) and solid-state nuclear magnetic resonance (NMR). The crystallite size (crystallinity) and microstrains were analyzed using XRD with the Rietveld refinement technique and the Halder–Wagner method. The 31P and 1H NMR chemical environments were analyzed by two-dimensional (2D) 1H-31P heteronuclear-correlation (HETCOR) magic-angle spinning (MAS) NMR spectroscopy. Enamel had a greater crystallite size and fewer microstrains than dentin for both bovine and human teeth. When compared between the species, the bovine apatite had a smaller crystallite size with more microstrains than the human apatite for both dentin and enamel. The 2D HETCOR spectra demonstrated that a water-rich layer and inorganic HPO42− ions were abundant in dentin; meanwhile, the hydroxyl group in the lattice site was more dominant in enamel. A greater intensity of the hydroxyl group was detected in human than in bovine for both dentin and enamel. For 31P projections, bovine dentin and bovine enamel have wider linewidths than human dentin and human enamel, respectively. There are differences in the crystallite profile between human and bovine. The results of dental research should be interpreted with caution when bovine teeth are substituted for human teeth. [ABSTRACT FROM AUTHOR]

Two heteroctanuclear Au4Ag4 cluster complexes of 4,5-diethynylacridin-9-one (H2L) were prepared through the self-assembly reactions of [Au(tht)2](CF3SO3), Ag(tht)(CF3SO3), H2L and PPh3 or PPh2Py (2-(diphenylphosphino)pyridine). The Au4Ag4 cluster consists of a [Au4L4]4− and four [Ag(PPh3)]+ or [Ag(PPh2Py)]+ units with Au4L4 framework exhibiting a twisted paper clip structure. In CH2Cl2 solutions at ambient temperature, both compounds show ligand fluorescence at ca. 463 nm as well as phosphorescence at 650 nm for 1 and 630 nm for 2 resulting from admixture of 3IL (intraligand) of L ligand, 3LMCT (from L ligand to Au4Ag4) and 3MC (metal-cluster) triplet states. Crystals or crystalline powders manifest bright yellow-green phosphorescence with vibronic-structured emission bands at 530 (568sh) nm for complex 1 and 536 (576sh) nm for complex 2. Upon mechanical grinding, yellow-green emission in the crystalline state is dramatically converted to red luminescence centered at ca. 610 nm with a drastic redshift of the emission after crystal packing is destroyed. [ABSTRACT FROM AUTHOR]

Dental research often uses bovine teeth as a substitute for human teeth. The aim of this study was to evaluate differences in the crystalline nanostructures of enamel and dentin between bovine and human teeth, using X-ray diffraction (XRD) and solid-state nuclear magnetic resonance (NMR). The crystallite size (crystallinity) and microstrains were analyzed using XRD with the Rietveld refinement technique and the Halder–Wagner method. The 31P and 1H NMR chemical environments were analyzed by two-dimensional (2D) 1H-31P heteronuclear-correlation (HETCOR) magic-angle spinning (MAS) NMR spectroscopy. Enamel had a greater crystallite size and fewer microstrains than dentin for both bovine and human teeth. When compared between the species, the bovine apatite had a smaller crystallite size with more microstrains than the human apatite for both dentin and enamel. The 2D HETCOR spectra demonstrated that a water-rich layer and inorganic HPO42− ions were abundant in dentin; meanwhile, the hydroxyl group in the lattice site was more dominant in enamel. A greater intensity of the hydroxyl group was detected in human than in bovine for both dentin and enamel. For 31P projections, bovine dentin and bovine enamel have wider linewidths than human dentin and human enamel, respectively. There are differences in the crystallite profile between human and bovine. The results of dental research should be interpreted with caution when bovine teeth are substituted for human teeth.

Two heteroctanuclear Au4Ag4 cluster complexes of 4,5-diethynylacridin-9-one (H2L) were prepared through the self-assembly reactions of [Au(tht)2](CF3SO3), Ag(tht)(CF3SO3), H2L and PPh3 or PPh2Py (2-(diphenylphosphino)pyridine). The Au4Ag4 cluster consists of a [Au4L4]4− and four [Ag(PPh3)]+ or [Ag(PPh2Py)]+ units with Au4L4 framework exhibiting a twisted paper clip structure. In CH2Cl2 solutions at ambient temperature, both compounds show ligand fluorescence at ca. 463 nm as well as phosphorescence at 650 nm for 1 and 630 nm for 2 resulting from admixture of 3IL (intraligand) of L ligand, 3LMCT (from L ligand to Au4Ag4) and 3MC (metal-cluster) triplet states. Crystals or crystalline powders manifest bright yellow-green phosphorescence with vibronic-structured emission bands at 530 (568sh) nm for complex 1 and 536 (576sh) nm for complex 2. Upon mechanical grinding, yellow-green emission in the crystalline state is dramatically converted to red luminescence centered at ca. 610 nm with a drastic redshift of the emission after crystal packing is destroyed.

A new hetero trinuclear manganese(III)-iron(II) complex, [Mn(salen)(H2O)]2[Fe(CN)6], in which salen is the dianionic form of N,N’-bis(5-methylsalicylidene)-1,2-diaminoethane, has been prepared and characterized by elemental analyses, IR, and single crystal X-ray crystallographic determination. The crystal of the complex is monoclinic: space group P21/c, a = 10.768(2), b = 14.248(3), c = 15.222(3) Å, β = 95.394(2)º, V = 2325.0(8) Å3, Z = 2, R1 = 0.0754, wR2 = 0.2366. The bis-Schiff base ligand coordinates to the Mn atom through phenolate O and imine N atoms. Each Mn atom in the complex is in octahedral coordination, with the equatorial donor atoms come from the Schiff base ligand, and with the axial donor atoms come from a water O atom and a cyanide N atom. The effects of the complex on the antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans were studied. DOI: http://dx.doi.org/10.4314/bcse.v29i3.8

The metallostibine Os 2 (CO) 8 ( μ -SbPh), 2 , acts as a good two-electron donor ligand, reacting readily with Group 8 metal carbonyls to give heterometallic clusters. Specifically, it undergoes ligand substitution reaction with Fe 2 (CO) 9 , Os 3 (CO) 11 (CH 3 CN), or Os 3 (CO) 10 (CH 3 CN) 2 to afford Os 2 Fe(CO) 12 ( μ 3 -SbPh), 3 , Os 5 (CO) 19 ( μ 3 -SbPh), 4 , or Os 7 (CO) 26 ( μ 3 -SbPh) 2 , 5 , respectively, in moderate to high yields. An analogous reaction with Ru 3 (CO) 11 (CH 3 CN) afforded another spirocyclic cluster Os 3 Ru(CO) 14 ( μ -PhCO)( μ 4 -Sb), 9 . UV irradiation of 4 afforded the spirocyclic clusters Os 5 (CO) 18 ( μ , η 2 -PhCO)( μ 4 -Sb), 6 , and Os 5 (CO) 18 ( μ , η 2 -C 6 H 4 )( μ -H)( μ 4 -Sb), 7 , while the raft-like cluster Os 5 (CO) 19 ( μ 3 -SbPh), 8 , was obtained when a methanolic solution was exposed to natural light; cluster 5 failed to react under similar conditions. All the new clusters have been characterized spectroscopically and crystallographically, and possible pathways for the formation of 6 - 9 proposed. [ABSTRACT FROM AUTHOR]

Leveraging the demonstrated accuracy of the group contribution statistical associating fluid theory for potentials of variable range (GC-SAFT-VR) equation of state to predict the phase equilibrium and thermodynamic properties of fluids, we use this approach to study organic sulfur molecules and their mixtures. Knowledge of the phase equilibria and thermodynamic properties of sulfur containing compounds, while of interest in a number of fields, is important to the development of petroleum products with lower sulfur content. In this work the CH (thiophene) and –S- functional groups are characterized by fitting to experimental data for pure thiophene and cross interactions determined in order to extend the GC-SAFT-VR equation of state to the study of organic sulfur molecules. Theoretical predictions are compared with experimental results for the phase behavior of 3-methylthiophene, 2-methylthiophene, and benzothiophene, as well as their binary mixtures with alkanes, alkenes, aromatics, carbon dioxide, and alcohols. As far as we are aware, this work is the first SAFT-based study of mixtures containing thiophene molecules with aromatics, alcohols, and hydrocarbon molecules. The GC-SAFT-VR approach is found to accurately predict the phase behavior of the sulfur organic compounds studied, providing a method to determine the phase behavior of these compounds without heavy reliance on experimental data. [ABSTRACT FROM AUTHOR]

Fluorinated molecules such as perfluoroalkanes (PFA), perfluoroalkylalkanes (PFAA), fluoroalkanes, and hydrofluoroethers (HFE) possess attractive physical properties that have resulted in their use in a wide range of applications. However, while there is an abundance of thermophysical data for hydrocarbons in the literature, only limited studies have been performed that report the properties of the corresponding fluorinated species. Predictive approaches are therefore needed to accurately and reliably determine the physical properties of these molecules. The statistical associating fluid theory (SAFT) is a commonly used molecular-based equation of state that in its various forms has been applied to study a wide range of fluid systems. In recent work, several group contribution (GC) SAFT equations of state have been proposed, such as the GC-SAFT-VR equation that combines the SAFT equation for potentials of variable range (VR) with a group contribution approach that uniquely allows for the description of hetero-segmented chains. The GC-SAFT-VR equation has been shown to provide an excellent description of the phase behavior of pure associating and non-associating fluids and their mixtures, with a minimal reliance on fitting the model parameters to experimental data. Specifically, parameters for key functional groups (such as CH 3 , CH 2 , CH, CH 2 =CH, C=O, C 6 H 5 , ether and ester, OH, NH 2 , CH=O, COOH) have been obtained by fitting to experimental vapor pressure and saturated liquid density data for selected low molecular weight fluids and then used to predict the phase behavior of pure fluids and their mixtures without further adjusting the group parameters. To expand upon this effort, here we report parameters for the CF 3 , CF 2 , CF, CH 2 F, CHF 2 , and CHF functional groups and their cross interactions. The theoretical predictions are compared with experimental data for pure PFAs, PFAAs, and HFEs, as well as binary mixtures of alkanes, alkenes, PFAs, PFAAs, and CO 2 in order to test the transferability of the new group parameters. The GC-SAFT-VR approach is found to accurately predict the phase behavior of the systems studied. [ABSTRACT FROM AUTHOR]

Biodiesel fuels, which consist of a blend of long chain fatty acid methyl esters, have attracted increased interest in recent years as possible alternates to fuels derived from petroleum. An understanding of the thermophysical properties and phase behavior of these molecules are therefore important to the investigation and design of biodiesel processes; however, such data is limited, making the development of molecular based modeling approaches that can accurately and reliably determine the thermophysical properties of fatty acid methyl esters an important research area. Here we apply the group contribution based statistical associating fluid theory for potential of variable range (GC-SAFT-VR) equation of state to the study of long chain fatty acid methyl esters that comprise biodiesel fuels. With minimal reliance on experimental data, the GC-SAFT-VR equation of state offers a predictive approach that allows for the description of hetero-segmented chains that can correlate and predict the phase behavior of pure associating and non-associating fluids and their mixtures. Model parameters for the C O, CH 3 , CH 2 , CH CH 2 , OCH 2 , and OCH 3 functional groups and their cross interactions were taken from earlier work and used here in a transferable fashion to predict the thermophysical properties and phase behavior of pure fatty acid methyl esters and their mixtures with other fatty acid methyl esters, alcohols, and carbon dioxide. It is shown that the GC-SAFT-VR approach can be used as a purely predictive tool without fitting any new model parameters) to accurately predict the phase behavior of the fatty acid methyl ester fluids and their mixtures studied. [ABSTRACT FROM AUTHOR]

A new hetero trinuclear manganese(III)-iron(II) complex, [Mn(salen)(H2O)] 2[Fe(CN)6], in which salen is the dianionic form of N,N'-bis(5-methylsalicylidene)-1,2-diaminoethane, has been prepared and characterized by elemental analyses, IR, and single crystal X-ray crystallographic determination. The crystal of the complex is monoclinic: space group P21/c, a = 10.768(2), b = 14.248(3), c = 15.222(3) Å, β = 95.394(2)º, V = 2325.0(8) ų, Z = 2, R1 = 0.0754, wR2 = 0.2366. The bis-Schiff base ligand coordinates to the Mn atom through phenolate O and imine N atoms. Each Mn atom in the complex is in octahedral coordination, with the equatorial donor atoms come from the Schiff base ligand, and with the axial donor atoms come from a water O atom and a cyanide N atom. The effects of the complex on the antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans were studied. [ABSTRACT FROM AUTHOR]

Highlights: [•] A T box riboswitch Specifier domain–tRNA anticodon arm complex was prepared. [•] The complex mirrors ribosomal codon–anticodon pairing with three base pairs. [•] Specifier bases rotate towards the minor groove to engage the tRNA anticodon. [•] The structure of the anticodon loop evolves to adopt a U-turn motif in the complex. [•] Loss of the U-turn reduces affinity but does not prevent complex formation. [ABSTRACT FROM AUTHOR]

Highlights: [•] A T box riboswitch Specifier domain–tRNA anticodon arm complex was prepared. [•] The complex mirrors ribosomal codon–anticodon pairing with three base pairs. [•] Specifier bases rotate towards the minor groove to engage the tRNA anticodon. [•] The structure of the anticodon loop evolves to adopt a U-turn motif in the complex. [•] Loss of the U-turn reduces affinity but does not prevent complex formation. [ABSTRACT FROM AUTHOR]

Abstract: The hetero-segmented version of the statistical associating fluid theory for potentials of variable range (hetero-SAFT-VR) is used to develop a predictive molecular-based group-contribution SAFT-VR equation of state (GC-SAFT-VR). The hetero-SAFT-VR approach models molecules composed of segments of different size and/or energies of interaction enabling an accurate description of real molecules composed of different functional groups. The differences in interactions between functional groups are maintained throughout the theory in contrast to other approaches in which the parameters for functional groups are averaged in order to model a molecule as a homonuclear chain with “group-averaged” parameters. Through the GC-SAFT-VR approach we can study the effect of molecular functionality and topology on the thermodynamic properties of real fluid systems, since parameters are determined for each functional group and chain connectivity is explicitly specified. In this initial study GC-SAFT-VR parameters are developed for key organic functional groups (CH3, CH2, CH2 glyph name="dbnd" />O, C6H5, OCH3 and OCH2) by fitting to experimental vapor pressure and saturated liquid density data for a selected group of compounds that contain these functional groups. The transferability of the parameters obtained is tested by comparing theoretical predictions with experimental data for pure fluids not included in the fitting process and binary mixtures. Using the GC-SAFT-VR approach good agreement is obtained between experimental data and the theoretical predictions for pure substances, including isomers, and their mixtures. The GC-SAFT-VR approach is able to accurately predict the effect of molecular functionality on mixture phase behavior without fitting to any experimental data for the system being studied. [Copyright &y& Elsevier]

Abstract: A new group contribution (GC) approach based on the statistical associating fluid theory (SAFT-) has recently been proposed [A. Lymperiadis, C. S. Adjiman, A. Galindo, G. Jackson, J. Chem. Phys. 127 (2007) 234903]. In this continuum equation of state GC approach, the molecules are formed from fused heteronuclear spherical segments each of which represents a distinct chemical functional group. The different segments are characterised by size and attractive energy (well-depth and range) parameters, and a shape-factor parameter which describes the contribution that each segment makes to the overall molecular properties. In addition a number of bonding sites are included on a given segment to deal with association interactions where appropriate; the association between sites introduces two additional energy and range parameters. Our heteronuclear molecular models are thus fundamentally different from the homonuclear models employed with other GC versions of SAFT in which the GC concept is introduced to obtain average molecular parameters. In the current work, we generalise the SAFT- equation of state to treat chemical groups which are represented by more than a single spherical segment. This allows for a good description of the properties of large functional groups such as carboxyl and carbonyl groups. The original parameter table for the CH3, CH2, CH3CH, ACH (where AC denotes an aromatic carbon), ACCH2, CH2 lyph name="dbnd" /> and OH groups is now extended to include the Cand NH2 groups by examining the vapour–liquid equilibria (VLE) of pure 2-ketones, carboxylic acids, and primary amines. It is demonstrated that the proposed theory provides an excellent description of the vapour–liquid equilibria for all of the chemical families considered, and that the new group parameters can be used in a predictive fashion to model the phase behaviour of larger compounds not included in the estimation database. One of the principal advantages of the SAFT- formalism is that the binary interaction parameters between groups of different types can be estimated from pure component data alone. This is particularly useful in describing the properties of fluid mixtures. The adequacy of the method in predicting the VLE is assessed for selected binary mixtures of associating and non-associating compounds. A strict test of any GC method is its ability to capture both vapour–liquid and liquid–liquid equilibria (LLE) with the same set of group parameters. It is very gratifying to find that with SAFT- one is able to reproduce the VLE and LLE behaviour for several mixtures simultaneously, for example, n- , and n- . [Copyright &y& Elsevier]

Abstract: The reaction of Cp*Ir(CO)2 or CpIr(CO)2 with Ru3(CO)12 under a hydrogen atmosphere afforded the heterometallic clusters Cp*IrRu3(μ-H)2(CO)10 and CpIrRu3(μ-H)2(CO)10, respectively, in moderate yields. In the former reaction, the tetrahydrido cluster Cp*IrRu3(μ-H)4(CO)9 was also formed in trace amounts, although this cluster can be obtained in high yields by the hydrogenation of Cp*IrRu3(μ-H)2(CO)10; the Cp analogue was not obtainable. The reaction of Os3(μ-H)2(CO)10 with Cp*Ir(CO)2 afforded the osmium analogue Cp*IrOs3(μ-H)2(CO)10 in 70% yield, along with a trace amount of the pentanuclear cluster Cp*IrOs4(μ-H)2(CO)13. Hydrogenation of Cp*IrOs3(μ-H)2(CO)10 afforded Cp*IrOs3(μ-H)4(CO)9 in excellent yield. The reaction of Cp*Ir(CO)2 with Os3(CO)10(CH3CN)2 afforded the known trinuclear cluster Cp*IrOs2(CO)9 and the novel cluster Cp*IrOs3(CO)11. Solution-state NMR studies show that the hydrides in the iridium–ruthenium clusters are highly fluxional even at low temperatures while those in the iridium–osmium clusters are less so. [Copyright &y& Elsevier]

Abstract: The reactions of the heterometallic cluster Cp*IrOs3(μ-H)2(CO)10 with phosphines, isonitriles and pyridine under TMNO activation afforded the substitution products Cp*IrOs3(μ-H)2(CO)10−n L n (n =1, 2; L=PPh3, P(OMe)3, t BuNC, CyNC or py) in good yields. For the monosubstituted derivatives, the substitution site was exclusively at an osmium atom in an axial position for L=phosphine or phosphite. Spectroscopic evidence suggested the presence of isomers in solution for the PPh3 derivative. In contrast, for L=isonitrile, the ligand occupied an equatorial site. In the disubstituted derivatives, the group 15 ligands were coordinated to two different osmium atoms, one each at an axial and an equatorial site. The isomerism and fluxional behaviour of some of these clusters have also been examined. [Copyright &y& Elsevier]

Abstract: TMNO-activated reaction of the heteronuclear cluster Os3Ru(μ-H)2(CO)13 (1) with diphenylphosphine afforded the novel phosphido-bridged clusters Os3Ru(μ-PPh2)(μ-H)3(CO)11 (2), Os3Ru(μ-PPh2)2(μ-H)2(CO)10 (3), Os3Ru(μ-PPh2)2(μ-H)4(CO)9 (4), and Os3Ru(μ-PPh2)(μ-H)3(CO)11(PPh2H) (5). The formation of 2–5 proceeded via P–H bond cleavage in the adduct Os3Ru(μ-H)2(CO)12(PPh2H) (6). Reaction of 2 with PPh3 afforded the adduct Os3Ru(μ-PPh2)(μ-H)3(CO)11(PPh3) (7) and the substituted derivative Os3Ru(μ-PPh2)(μ-H)3(CO)10(PPh3) (8). [Copyright &y& Elsevier]

We report in this account on the controlled synthesis of novel d0–d8 early-late heteropolynuclear diolefin and carbonyl clusters. The synthetic approach was based on additive–deprotonation reactions involving the titanium and zirconium bis-hydrosulphido complexes of formula [Cp2Ti(SH)2] and [Cptt2Zr(SH)2] and appropriate rhodium and iridium diolefin and carbonyl compounds. The significant differences between the resulting early-late complexes and their structures coming from the titanium or zirconium metalloligand precursors are highlighted. The catalytic activity of some representative titanium–rhodium and zirconium–rhodium compounds towards alkene hydroformylation was explored. Interestingly, the heterotetranuclear ‘CpTi(μ3-S)3Rh3’ structure was maintained as such under mild conditions. To cite this article: L.A. Oro et al., C. R. Chimie 6 (2003) 000–000. [Copyright &y& Elsevier]

Organometallic compounds are increasingly recognized as promising anticancer and antibiotic drug candidates. Among the transition metal ions investigated for these purposes, rhenium occupies a special role. Its tri- and dicarbonyl complexes, in particular, attract continuous attention due to their relative ease of preparation, stability and unique photophysical and luminescent properties that allow the combination of diagnostic and therapeutic purposes, thereby permitting, e.g., molecules to be tracked within cells. In this review, we discuss the anticancer and antibiotic properties of rhenium tri- and dicarbonyl complexes described in the last seven years, mainly in terms of their structural variations and in vitro efficacy. Given the abundant literature available, the focus is initially directed on tricarbonyl complexes of rhenium. Dicarbonyl species of the metal ion, which are slowly gaining momentum, are discussed in the second part in terms of future perspective for the possible developments in the field. [ABSTRACT FROM AUTHOR]

A method, based on linewidth measurements, is described which permits the rapid and facile determination of JHNHα coupling constants from 15N labeled proteins. Using appropriately processed HMQC-J data, we have found that a simple linear relationship exists between the half-height linewidth (Δν1/2) of 15N–1H cross peaks and their corresponding JHNHα coupling constants. Tests indicate that this technique permits the accurate measurement of up to 100 JHNHα coupling constants in less than 30 min. Furthermore, the JHNHα measurements can be done manually – without the need of any computer-based curve-fitting or minimization. Comparisons between JHNHα values predicted from high resolution X-ray structures and those determined using this technique indicate that the method is both accurate and precise (correlation coefficient = 0.90, rmsd = 0.75 Hz). [ABSTRACT FROM AUTHOR]

In this article, we report on the synthesis and characterization of the tetracarboxylatodirhodium(II) complexes [Rh2(μ–O2CCH2OMe)4(THF)2] (1) and [Rh2(μ–O2CC6H4–p–CMe3)4(OH2)2] (2) by metathesis reaction of [Rh2(μ–O2CMe)4] with the corresponding ligand acting also as the reaction solvent. The reaction of the corresponding tetracarboxylato precursor, [Rh2(μ–O2CR)4], with PPh4[Au(CN)2] at room temperature, yielded the one-dimensional polymers (PPh4)n[Rh2(μ–O2CR)4Au(CN)2]n (R = Me (3), CH2OMe (4), CH2OEt (5)) and the non-polymeric compounds (PPh4)2{Rh2(μ–O2CR)4[Au(CN)2]2} (R = CMe3 (6), C6H4–p–CMe3 (7)). The structural characterization of 1, 3·2CH2Cl2, 4·3CH2Cl2, 5, 6, and 7·2OCMe2 is also provided with a detailed description of their crystal structures and intermolecular interactions. The polymeric compounds 3·2CH2Cl2, 4·3CH2Cl2, and 5 show wavy chains with Rh–Au–Rh and Rh–N–C angles in the ranges 177.18°–178.69° and 163.0°–170.4°, respectively. A comparative study with related rhodium-silver complexes previously reported indicates no significant influence of the gold or silver atoms in the solid-state arrangement of these kinds of complexes. [ABSTRACT FROM AUTHOR]

Herein, we describe the preparation of heteronuclear dirhodium-silver complexes by reaction between molecular Rh(II)-Rh(II) compounds [Rh2(μ-O2CR)4L2] (R = Me, Ph (1), CH2OEt (2); L = solvent molecules) with paddlewheel structure and PPh4[Ag(CN)2]. One-dimensional coordination polymers of (PPh4)n[Rh2(μ-O2CR)4Ag(CN)2]n (R = Me (3), Ph (4), CH2OEt (5)) formula have been obtained by replacement of the two labile molecules in the axial positions of the paddlewheel structures by a [Ag(CN)2]− bridging unit. The crystal structures of 3–5 display a similar arrangement, having anionic chains with a wavy structure and bulky (PPh4)+ cations placed between the chains. The presence of the (PPh4)+ cations hinders the existence of intermolecular Ag-Ag interactions although several C-H····π interactions have been observed. A similar reaction between [Rh2(μ-O2CCMe3)4(HO2CCMe3)2] and PPh4[Ag(CN)2] led to the molecular compound (PPh4)2{Rh2(μ-O2CCMe3)4[Ag(CN)2]2} (6) by replacement of the axial HO2CCMe3 ligands by two [Ag(CN)2]− units. The trimethylacetate ligand increases the solubility of the complex during the crystallization favouring the formation of discrete heteronuclear species. [ABSTRACT FROM AUTHOR]