Syntheses and metal-catalyzed C---H bond activation of Alkyne π complexes of copper(I) Trifluoromethanesulfonate

The copper(I) trifluoromethanesulfonate π complexes of 1,8-cyclotetradecadiyne and 1,7-octadiyne have been synthesized. For a series of terminal alkyne (CuO₃SCF₃) π complexes, vibrational spectra show weakening of both C ≡C and C_sp-H bonds upon copper(I) coordination. NMR analysis shows less Cu(I) caused deshielding of C(1) than C(2) of the alkyne and increased C_sp-H coupling. Copper(I) π coordination to terminal alkynes increases the rate of exchange of protium on C(1) for deuterium from CD₃COOD. Copper enhances the rate of exchange by a factor of 1.2 x 10⁵ with 1,7-octadiyne. The exchange is catalytic in copper(I) and is faster than the rate of copper alkynide formation in the absence of deuterium donor. Copper(I) catalyzes deuterium exchange for protium at C(1) between 1,7-octadiyne and 1-hexyne-1-d₁.     

Unsaturated macrocyclic compounds-CIX : Synthesis of a tetradehydrotetraaza[32]annulene

The conjugated aldehydes 6,9, and 12, containing terminal acetylenes, were prepared and converted to the corresponding azines 13, 14, and 15, respectively. Oxidative coupling of 14 gave the corresponding cyclic “dimer” 16, a tetradehydrotetraaza[32]annulene. Although 16 is a 4n π-electron system, the ¹H-NMR spectrum showed it to be an atropic molecule.     

<Superscript>103</Superscript>Rh, <Superscript>17</Superscript>O,and <Superscript>31</Superscript>P NMR study of Rh(III) complex formation in acidic sulfate-phosphate media

Rhodium(III) complex formation with phosphoric acid in strong acidic solutions has been studied by ¹⁰³Rh, ¹⁷O, and ³¹P NMR. Phosphoric acid is mainly coordinated to rhodium as a monodentate terminal HPO₄²⁻ ion, while the coordinated phosphate ion accounts for no more than 7%.     

Pair distribution function and 71Ga NMR study of aqueous Ga3+ complexes

The atomic structures, and thereby the coordination chemistry, of metal ions in aqueous solution represent a cornerstone of chemistry, since they provide first steps in rationalizing generally observed chemical information. However, accurate structural information about metal ion solution species is often surprisingly scarce. Here, the atomic structures of Ga³⁺ ion complexes were determined directly in aqueous solutions across a wide range of pH, counter anions and concentrations by X-ray pair distribution function analysis and ⁷¹Ga NMR. At low pH (<2) octahedrally coordinated gallium dominates as either monomers with a high degree of solvent ordering or as Ga-dimers. At slightly higher pH (pH ≈ 2–3) a polyoxogallate structure is identified as either Ga₃₀ or Ga₃₂ in contradiction with the previously proposed Ga₁₃ Keggin structures. At neutral and slightly higher pH nanosized GaOOH particles form, whereas for pH > 12 tetrahedrally coordinated gallium ions surrounded by ordered solvent are observed. The effects of varying either the concentration or counter anion were minimal. The present study provides the first comprehensive structural exploration of the aqueous chemistry of Ga³⁺ ions with atomic resolution, which is relevant for both semiconductor fabrication and medical applications.

With changing pH four different structural regions in Ga³⁺ aqueous solutions are observed. In contrast the effects of different anions and concentrations are minimal.     

A direct nitrogen-15 NMR study of praseodymium(III)-nitrate complex formation in aqueous solvent mixtures

A direct, low-temperature nitrogen-15(¹⁵N) NMR technique has been applied to the study of inner-shell complex formation between praseodymium(III) and nitrate ion in aqueous solvent mixtures. In water-acetone mixtures at –95°C, ligand exchange is slow enough to permit the observation of¹⁵N NMR signals for uncomplexed and coordinated nitrate ion, but satisfactory resolution is obtained only by the addition of Freon-12 to these systems for study at –110 to –115°C. Four coordinated nitrate signals are generally observed and a very small signal for an additional complex, or an isomer of one of the others, appears at the highest nitrate concentrations. Signals for the mono-and dinitrato complexes are unambiguously identified, but with the exception of the trinitrato complex, several possibilities exist for the remaining peaks. To overcome excessive viscosity signal broadening, measurements in methanol and ethanol are possible only with praseodymium trifluoromethanesulfonate (triflate). Coordinated nitrate signals in aqueous and anhydrous methanol are observed only for the mono-and dinitrato species, and signal areas indicate a maximum of two moles of nitrate per Pr(III) are complexed. A third signal is evident in the ethanol solution spectra, and the presence of this higher complex was confirmed by area measurement of the fraction of bound nitrate. The extent of complex formation in these solvent systems is attributed to differences in the dielectric constant. A comparison of the complexing tendencies of Pr(III) to other ions studied by this NMR method suggests the possibility of a coordination number change across the lanthanide series. Preliminary¹⁵N NMR results for metal-ion complexes with the isothiocyanate ion are presented.     

DFT Calculations of 1H NMR Chemical Shifts of Geometric Isomers of Conjugated Linolenic Acids,Hexadecatrienyl Pheromones,and Model Triene-Containing Compounds: Structures in Solution and Revision of NMR Assignments

A DFT study of the ¹H NMR chemical shifts, δ(¹H), of geometric isomers of 18:3 conjugated linolenic acids (CLnAs), hexadecatrienyl pheromones, and model triene-containing compounds is presented, using standard functionals (B3LYP and PBE0) as well as corrections for dispersion interactions (B3LYP-D3, APFD, M06–2X and ωB97XD). The results are compared with literature experimental δ(¹H) data in solution. The closely spaced “inside” olefinic protons are significantly more deshielded due to short-range through-space H^…H steric interactions and appear close to or even beyond δ-values of aromatic systems. Several regularities of the computational δ(¹H) of the olefinic protons of the conjugated double bonds are reproduced very accurately for the lowest-energy DFT-optimized single conformer for all functionals used and are in very good agreement with experimental δ(¹H) in solution. Examples are provided of literature studies in which experimental resonance assignments deviate significantly from DFT predictions and, thus, should be revised. We conclude that DFT calculations of ¹H chemical shifts of trienyl compounds are powerful tools (i) for the accurate prediction of δ(¹H) even with less demanding functionals and basis sets; (ii) for the unequivocal identification of geometric isomerism of conjugated trienyl systems that occur in nature; (iii) for tackling complex problems of experimental resonance assignments due to extensive signal overlap; and (iv) for structure elucidation in solution.     

Synthesis and Structural Characterization of a Silver(I) Pyrazolato Coordination Polymer

Coinage metal(I)···metal(I) interactions are widely of interest in fields such as supramolecular assembly and unique luminescent properties, etc. Only two types of polynuclear silver(I) pyrazolato complexes have been reported, however, and no detailed spectroscopic characterizations have been reported. An unexpected synthetic method yielded a polynuclear silver(I) complex [Ag(μ-L1Clpz)]_n (L1Clpz⁻ = 4-chloride-3,5-diisopropyl-1-pyrazolate anion) by the reaction of {[Ag(μ-L1Clpz)]₃}₂ with (ⁿBu₄N)[Ag(CN)₂]. The obtained structure was compared with the known hexanuclear silver(I) complex {[Ag(μ-L1Clpz)]₃}₂. The Ag···Ag distances in [Ag(μ-L1Clpz)]_n are slightly shorter than twice Bondi’s van der Waals radius, indicating some Ag···Ag argentophilic interactions. Two Ag–N distances in [Ag(μ-L1Clpz)]_n were found: 2.0760(13) and 2.0716(13) Å, and their N–Ag–N bond angles of 180.00(7)° and 179.83(5)° indicate that each silver(I) ion is coordinated by two pyrazolyl nitrogen atoms with an almost linear coordination. Every five pyrazoles point in the same direction to form a 1-D zig-zag structure. Some spectroscopic properties of [Ag(μ-L1Clpz)]_n in the solid-state are different from those of {[Ag(μ-L1Clpz)]₃}₂ (especially in the absorption and emission spectra), presumably attributable to this zig-zag structure having longer but differently arranged intramolecular Ag···Ag interactions of 3.39171(17) Å. This result clearly demonstrates the different physicochemical properties in the solid-state between 1-D coordination polymer and metalacyclic trinuclear (hexanuclear) or tetranuclear silver(I) pyrazolate complexes.     

The role of the activity coefficients of surface groups in the formation of surface charge of oxides. Part II: Ion exchange and ζ potentials

A new method is developed to calculate the surface charge densities and potentials of oxides in contact with electrolyte solution as functions of pH and ionic strength. For low ionic strength and not too far from p.z.c. (up to 3 pH units for 10^–3 mol dm^–3 NaCl) the previous model (Kosmulski, 1992) neglecting the ion exchange can be used but farther from p.z.c., correction for the ion exchange is necessary for some systems. This correction leads to increase of the calculated titration charge (that is not necessarily equal to the surface charge), but does not affect the diffuse charge and potential.     

Synthesis and crystal and molecular structure of Mo4O(OCH2But)10(py): A 12-electron butterfly cluster

From the reaction between Mo₂(OCH₂Bu^t)₆ and water (1/2 equiv) in toluene solution in the presence of pyridine the oxo-alkoxide tetranuclear cluster Mo₄O(OCH₂Bu^t)₁₀(py) has been isolated as a dark crystalline compound. Crystal data at –121°C:a=24.762(12) Å,b=24.799(9) Å,c=23.021(9) Å,Z=8,d _caled=1.27 g cm^–3 in space group 14/m. The compound contains a Mo₄ butterfly with a hinge angle of 137° between the two Mo₃ triangles. The molecule has a crystallographically-imposed mirror plane of symmetry that contains the wing-tip Mo atoms. One wing-tip Mo atom is in an octahedral environment being bonded to two terminal and two-bridging OR ligands, and one pyridine ligand that is trans to a ₃-oxo bridge. The other Mo atoms are each coordinated to only four oxygen atoms. The backbone Mo atoms have one terminal and two bridging OR ligands and form one bond each to the ₃-oxo group. The other wing-tip Mo atom is coordinated to two terminal and two bridging OR groups. The five Mo-Mo distances span the range 2.43–2.59 Å. The¹H and¹³C{¹H} NMR spectra in benzene-d₆ are consistent with the presence of this structure in solution. The present results are compared to earlier findings for 12-electron alkoxide clusters of Mo and W.     

Visible light driven deuteration of formyl C–H and hydridic C(sp3)–H bonds in feedstock chemicals and pharmaceutical molecules

Deuterium labelled compounds are of significant importance in chemical mechanism investigations, mass spectrometric studies, diagnoses of drug metabolisms, and pharmaceutical discovery. Herein, we report an efficient hydrogen deuterium exchange reaction using deuterium oxide (D₂O) as the deuterium source, enabled by merging a tetra-n-butylammonium decatungstate (TBADT) hydrogen atom transfer photocatalyst and a thiol catalyst under light irradiation at 390 nm. This deuteration protocol is effective with formyl C–H bonds and a wide range of hydridic C(sp³)–H bonds (e.g. α-oxy, α-thioxy, α-amino, benzylic, and unactivated tertiary C(sp³)–H bonds). It has been successfully applied to the high incorporation of deuterium in 38 feedstock chemicals, 15 pharmaceutical compounds, and 6 drug precursors. Sequential deuteration between formyl C–H bonds of aldehydes and other activated hydridic C(sp³)–H bonds can be achieved in a selective manner.

A selective hydrogen deuterium exchange reaction with formyl C–H bonds and a wide range of hydridic C(sp³)–H bonds has been achieved by merging tetra-n-butylammonium decatungstate photocatalyst and a thiol catalyst under 390 nm light irradiation.     

A hydrogen-1, nitrogen-15, and chlorine-35 NMR coordination study of Lu(ClO4)3 and Lu(NO3)3 in aqueous solvent mixtures

A coordination study of Lu(III) has been carried out for the nitrate and perchlorate salts in aqueous mixtures of acetone-d₆ and Freon-12 by¹H,¹⁵N and³⁵Cl NMR spectroscopy. At temperatures lower than –90°C, proton and ligand exchange are slow enough to permit the direct observation of¹H resonance signals for coordinated and free water molecules, leading to an accurate measure of the Lu(III) hydration number. In perchlorate solution, in the absence of inner-shell ion-pairing, Lu(III) exhibits a maximum coordination number of six over the allowable concentration range of study, contrasting markedly with the report of values of six to nine or greater as determined by a similar NMR method. The absence of contact ion-pairing was confirmed by³⁵Cl NMR chemical shift and linewidth measurements. Extensive ion-pairing was observed in the nitrate solutions as reflected by the lower Lu(III) hydration numbers of two to three in these systems, the observation of two coordinated water signals, and¹⁵N NMR signals for two complexes. The¹H and¹⁵N NMR spectra and the hydration number could be accounted for by the presence of (H₂O)₄Lu(NO₃)²⁺ and (H₂O)₂Lu(NO₃) ₂ ¹⁺ .     

Five-coordinate pentafluorobenzothiolate osmium(IV) complexes [Os(SC6F5)4(P(C6H4X-4)3)] (X = OCH3, CH3, F, Cl or CF3): Solid and solution structural characterization

The reactions of OsO₄ with excess of HSC₆F₅ and P(C₆H₄X-4)₃ in ethanol afford the five-coordinate compounds [Os(SC₆F₅)₄(P(C₆H₄X-4)₃)] where X = OCH₃ 1a and 1b, CH₃ 2a and 2b, F 3a and 3b, Cl 4a and 4b or CF₃ 5a and 5b. Single crystal X-ray diffraction studies of 1 to 5 exhibit a common pattern with an osmium center in a trigonal-bipyramidal coordination arrangement. The axial positions are occupied by mutually trans thiolate and phosphane ligands, while the remaining three equatorial positions are occupied by three thiolate ligands. The three pentafluorophenyl rings of the equatorial ligands are directed upwards, away from the axial phosphane ligand in the arrangement “3-up” (isomers a). On the other hand, ³¹P{¹H} and ¹⁹F NMR studies at room temperature reveal the presence of two isomers in solution: The “3-up” isomer (a) with the three C₆F₅-rings of the equatorial ligands directed towards the axial thiolate ligand, and the “2-up, 1-down” isomer (b) with two C₆F₅-rings of the equatorial ligands directed towards the axial thiolate and the C₆F₅-ring of the third equatorial ligand directed towards the axial phosphane. Bidimensional ¹⁹F–¹⁹F NMR studies encompass the two sub-spectra for the isomers a (“3-up”) and b (“2-up, 1-down”). Variable temperature ¹⁹F NMR experiments showed that these isomers are fluxional. Thus, the ¹⁹F NMR sub-spectra for the “2-up, 1-down” isomers (b) at room temperature indicate that the two S-C₆F₅ ligands in the 2-up equatorial positions have restricted rotation about their C–S bonds, but this rotation becomes free as the temperature increases. Room temperature ¹⁹F NMR spectra of 3 and 5 also indicate restricted rotation around the Os–P bonds in the “2-up, 1-down” isomers (b). In addition, as the temperature increases, the ¹⁹F NMR spectra tend to be consistent with an increased rate of the isomeric exchange. Variable temperature ³¹P{¹H} NMR studies also confirm that, as the temperature is increased, the a and b isomeric exchange becomes fast on the NMR time scale.     

A Direct Carbon-13 and Nitrogen-15 NMR Study of Cerium(III)–Isothiocyanate Complexation in Aqueous Solvent Mixtures

A study of lanthanide complexation with isothiocyanate is underway using a multinuclear magnetic resonance technique. For isothiocyanate solutions in water–acetone–Freon mixtures at low temperature, –85––125°C, ligand exchange is slow enough to permit the observation of ¹³C and ¹⁵N NMR signals for coordinated and free anions. For the Ce³⁺–NCS^– system, four coordinated anion signals, displaced from the free anion signal by about +450 to +550 ppm for ¹⁵N and +50 to +80 ppm for ¹³C, are observed. The ¹³C and ¹⁵N spectral data are complementary, showing a signal area concentration dependence and measured coordination numbers consistent with the formation of Ce(NCS)²⁺ through Ce(NCS)^1- ₄. In water–methanol, the extent of complexing is decreased, presumably because of the higher dielectric constant of this medium. In addition, the results of a competitive study of NCS^– and Cl^– ion binding, carried out using ³⁵Cl NMR, is presented.     

Copper-free and amine-free Sonogashira coupling in air in a mixed aqueous medium by palladium complexes of N/O-functionalized N-heterocyclic carbenes

Highly convenient copper-free and amine-free Sonogashira coupling of aryl bromides and iodides with terminal acetylenes under amenable conditions in air and in a mixed aqueous medium are reported using several new, user friendly and robust palladium precatalysts (1–5) of N/O-functionalized N-heterocyclic carbenes (NHCs). In particular, the precatalysts, 1 and 2, were synthesized from the imidazolium chloride salts by the treatment with PdCl₂ in pyridine in presence of K₂CO₃ as a base while the precatalysts, 3–5, were synthesized from the respective silver complexes by the treatment with (COD)PdCl₂. The DFT studies carried out on the 1–5 complexes suggest the presence of strong NHC–Pd σ-interactions arising out of deeply buried NHC–Pd σ-bonding molecular orbitals (MOs) that account for the inert nature of the metal–carbene bonds and also provide insights into the exceptional stability of these precatalysts.     

Direct hydrogen-1, carbon-13, and nitrogen-15 NMR study of magnesium(II)-isothiocyanate complexing

A hydrogen-1, carbon-13, and nitrogen-15 NMR study of magnesium(II)-isothiocyanate complexation in aqueous mixtures has been completed. At temperatures low enough to slow proton and ligand exchange, separate¹H,¹³C, and¹⁵N NMR signals are observed for coordinated and bulk water molecules and anions. The¹H NMR spectra reveal signals for the hexahydrate and the mono-through triisothiocyanato complexes, as well as two small signals attributed to [Mg(H₂O)₅(OH)]¹⁺ and [Mg(H₂O)₄(OH)(NCS)]. Accurate hydration numbers were obtained from signal area integrations at each NCS^– concentration. In the¹⁵N NMR spectra, signals also were observed for the mono-through triisothiocyanato complexes, and a small signal believed to be due to [Mg(H₂O)₄(OH)(NCS)]. Coordination number contributions for NCS^– were measured from these spectra and when combined with the hydration numbers they totalled essentially six at each anion concentration. Signals for [Mg(H₂O)₅(NCS)]¹⁺ through [Mg(H₂O)₃(NCS)₃]^1– also were observed in the¹³C NMR spectra and the area evaluations were comparable to the¹⁵N NMR results. An analysis of the magnitude and sign of the coordinated NCS^– chemical shifts identified the nitrogen atom as the anion binding site. All spectra indicated [Mg(H₂O)₅(NCS)]¹⁺ and [Mg(H₂O)₄(NCS)₂] were the dominat isothiocyanato complexes over the entire range of anion concentrations. The inability to detect evidence for complexes higher than the triisothiocyanato reflects the competitive binding ability of water molecules and perhaps the decreased electrostatic interaction between NCS^– and negatively charged higher complexes.     

Silver-water interactions: Part I. Model of the inner layer at the metal/water interface

Silver-water interactions, as expressed by the surface potential of the water molecules and the modification of the surface potential of the metal, are determined, at the potential of zero charge, as a function of the superficial structure of the electrode by means of the two more significant approaches, that based on the potential of zero charge-work function relation and that using the differential capacity of the inner-layer and its different components. The surface potential of water g^s(dip) is estimated from the inner-layer capacity while the modification of the surface potential of the metal δ_χ^M is obtained from theoretical calculations. The comparison of the [δ_gc^M − g^S(dip)] values with those deduced from the experimental pzc and work function is more than satisfactory. g^S(dip) is proposed to be equal to 0.19, 0.17 and 0.15 V, and −δ_χ^M equal to 0.41, 0.35 and 0.33 V, respectively for the (111), (100) and (110) faces of silver. Consequently, the strength of the silver-water interactions decreases from (111) to (110).The proposition of a large but electrode charge σ-independent capacitance contribution of the metal to the differential capacity of the inner layer Cⁱ is advanced from theoretical estimates and from the quantitative analysis of the Cⁱ(σ) curve for the mercury/water interface. The Cⁱ(σ) curve continues to represent the σ dependence of g^S(dip) as for the model with a σ- and metal-independent δ_χ^M. The basic change is that the capacity at fixed orientation of the water molecules C(ion) can no longer be identified with the minimum value of Cⁱ at high negative σ. A distance of 0.05 nm between the metal and the water molecules is proposed in order to interpret the low value of C(ion) equal to 8 μF cm⁻².The Cⁱ maximum located at the potential of zero charge for the three low-index faces of silver, is attributed to a maximum value of ∂g^S(dip)/∂σ, whatever the value of g^S(dip) for σ = 0 may be. On the other hand, the proposed estimates of the capacitance contribution of silver lead to an identical value of C(ion) and consequently to an identical structure of the inner layer at fixed orientation of the water molecules for the (111) face of silver as for mercury and the other sp metals. The same close-packed arrangement of the metal atoms at the surface of the electrode would be responsible for this identity.     

The effect of polyether ligands on the solution structure of [Li]-α-(phenylthio)benzyllithium in tetrahydrofuran: A H,Li-HOESY NMR study

[⁶Li]-α-(phenylthio)benzyllithium 1-⁶Li was studied in THF/[D₈]THF solution (1:1) in the presence of several acyclic and cyclic polyether ligands by ¹H,⁶Li-HOESY, ¹H and ¹³C NMR spectroscopy. The question whether these ligands are bonded to lithium or not is important for physical–organic investigations as well as for studies of the ground state of (stereoselective) reactions of organolithium compounds in the presence of such ligands. Dimethoxyethane is not bonded to lithium under these conditions. The acyclic ethers diglyme and triglyme coordinate only weakly to the organolithium compound and form contact ion pairs (CIPs) at 25°C. At −80°C, CIPs are in equilibrium with separated ion pairs (SIPs). Very stable complexes of 1-⁶Li are obtained with crown ether ligands. Addition of 12-crown-4 and 15-crown-5, respectively, results in the exclusive formation of SIPs at 25°C and −80°C. With 18-crown-6, a CIP–SIP equilibrium is observed at 25°C which is shifted entirely to the SIP side at −80°C. Graphical analyses of the ¹H and ¹³C NMR spectra of the polyether complexes of 1-⁶Li revealed correlations between the chemical shifts of the para phenyl carbon C-5, the para phenyl proton H-5, the benzylic carbon C-1, and the proton–carbon coupling constant J(C-1,H-1) of 1-Li, which are useful probes for the charge distribution within the carbanionic moiety of 1-⁶Li in the respective complexes, and thus for the ion pair character as a function of the polyether complexation of lithium.     

Formation of uniform silver particles from bis (1,2-ethanediamine)silver(I) complex

Uniform spherical silver particles were produced by decomposing the bis(1,2-ethanediamine)silver(I) complex, by aging a solution of 1.0×10^–3 mole dm^–3 in silver (I) nitrate, 1.0 mole dm^–3 in 1,2-ethanediamine, and 2.5×10^–1 mole dm^–3 in nitric acid (basic solution) at 100°C for 42 min. The average modal diameter was estimated to be 0.52 m with a relative standard deviation of 0.10. A moderately oxygenrich layer, 40 Å thick, on the surface of the particles was detected by means of photoelectron surface microanalysis (XPS). The silver particles grew through a polynuclear-layer mechanism, as judged from the concentration change in soluble silver(I) species in the supernatant solution. The particles' point of zero charge (PZC) was estimated at pH 6.5 by potentiometric titration.     

Cation recognition on a fullerene-based macrocycle

Heterocyclic orifices in cage-opened fullerene derivatives are regarded as potential ligands toward metals or ions, being reminiscent of truncated fullerenes as a hypothetical class of macrocycles with spherical π-conjugation. Among a number of cage-opened examples reported thus far, the coordination ability and dynamic behavior in solution still remained unclear due to difficulties in structural determination with multiple coordination sites on the macrocycles. Herein, we present the detailed solution dynamics of a cage-opened C₆₀ derivative bearing a diketo bis(hemiketal) moiety in the presence of alkali metal ions. The NMR spectroscopy disclosed the coordination behavior which is identified as a two-step process with a 1 : 2 stoichiometry. Upon coordination to the Li⁺ ion, the macrocycle largely varies its properties, i.e., increased absorption coefficients in the visible region due to weakly-allowed charge transfer transitions as well as the inner potential field from neutral to positive by the charge delocalization along with the spherical π-surface. The Li⁺-complexes formed in situ underwent unprecedented selective dehydroxyhydrogenation under high-pressure conditions. These findings would facilitate further studies on fullerene-based macrocycles as metal sensors, bulky ligands in organic reactions, and ion carriers in batteries and biosystems.

A fullerene-based Lewis-basic macrocyclic ligand underwent complexation with alkali-metal ions in 1 : 1 and 1 : 2 fashions, resulting in considerable perturbation to absorption properties as well as the potential surface inside the cage.     

Silver(I) thiosemicarbazone complex [Ag(catsc)(PPh3)2]NO3: Synthesis,characterization, crystal structure,and antibacterial study

We report the synthesis, characterization and crystal structure of a new mononuclear silver(I) complex, [Ag(catsc)(PPh₃)₂]NO₃ (catsc = 3-phenylpropenalthiosemicarbazone). The complex was prepared by the reaction of catsc and AgNO₃ in the presence of PPh₃ and characterized by elemental analysis (CHN), FTIR, ¹H, ¹³C and ³¹P NMR spectroscopy, and single-crystal X-ray diffraction. In the complex, catsc acts as a bidentate NS ligand while the nitrate is a counter ion. The silver ion is coordinated by a bidentate ligand and two PPh₃ in the form of a distorted tetrahedron. In addition, the antibacterial effect of the complex was studied against the standard strains of two gram-positive (Staphylococcus aureus and Enterococcus faecalis) and two gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria.