Assessment of soil quality of arable soils in Hungary using DRIFT spectroscopy and chemometrics

Nowadays, there is a great demand for precise, sensitive and adequate indicators for evaluating the quality of soils. In spite of recent developments in this field, a fast, non-destructive method for soil quality assessment has not yet been evaluated. The objective of this study was to investigate the possibility of using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy to estimate soil quality in the form of soil quality index (SQI). A set of soil samples (n = 89) was scanned and regression was carried out using a combination of DRIFT spectroscopy and partial least-squares (PLS). The reliability of the DRIFT-PLS calibration model (n = 53) was acceptable (coefficient of determination, R² = 0.49; residual prediction deviation, RPD = 1.4) for the estimating of the SQI values. The validation of the calibration model using a validation set (n = 36) of unknown samples also resulted in good acceptability with R² = 0.68 and RPD = 1.85. The DRIFT-PLS based model could provide a rapid, cheap estimate of SQI values and subsequently of soil quality by taking into account the integrated effects of the mineralogical and organic components of the soil. This approach could be useful to monitor soil quality under conditions where the analysis of a large number of soil samples is required.     

Spectroscopic studies and crystal structure of tetrabutylammonium trichlorodimethylstannate(IV): Bu4NSnMe2Cl3

The structure of Bu₄NSnMe₂Cl₃ is found to be monomer, containing a 5-coordinated bipyramidal trigonal tin(IV) center. Crystals belong to the monoclinic space group C2/c, with unit-cell dimensions a = 26.633(4) Å; b = 9.880(2) Å; c = 21.510(2) Å; β = 114.82(2)°; Z = 8; D = 1.287 Mg/m³; R is refined to 0.0537 and R_w = 0.0642 for 3330 reflections (F > 2σ(F)).     

Characterization and quantification of secondary metabolite profiles in leaves of red and white clover species by NIR and ATR-IR spectroscopy

Different varieties of two clover species (Trifolium pratense L. and Trifolium repens L.), cultivated in 2008 and 2009 were analysed by near-infrared (NIR) and mid-infrared (MIR) spectroscopy for establishing a fast and reliable quantification protocol for isoflavones and phenolic acids. Based on HPLC–UV/MS reference data, good results were obtained by PLS regression for the prediction of total isoflavone (R² = 0.90) as well as for glycitin content (R² = 0.88). Because of the lower concentration of formononetin and phenolic acids, their prediction quality was generally slightly lower (R² = 0.73 and R² = 0.64, respectively) compared to those of the isoflavones. The applicability of ‘leave one out’ cross validation for such a large data set is proven by comparison to an averaged randomized test-set validation leading to similar results. Additionally, the large sample set (n = 624) was screened by hierarchical cluster analysis allowing a fast evaluation of influences resulting from different cultivation parameters on the isoflavone and phenolic acid content. Climatic changes (cultivation year, date of harvest) seem to have the most impact on the metabolic profile as indicated by higher variability in the referring spectra when both cultivation years were simultaneously regarded. This work offers a new vibrational spectroscopic approach for the qualitative and quantitative determination of isoflavone and phenolic acid profiles, directly performed in the plant material without any laborious sample preparation and time-consuming chromatography. Once validated by HPLC reference, MIR and NIR spectroscopy can be used for the reliable prediction of secondary metabolites in clover as well as for fast screening and pre-evaluation of the diversity of a large sample set, aiming to reduce analytical costs, chemical waste and expenditure of time.     

Synthesis and asymmetric catalytic application of chiral imidazolium–phosphines derived from (1R,2R)-trans-diaminocyclohexane

Reaction between a chiral imidazole–amine precursor derived from (1R,2R)-trans-diaminocyclohexane and P¹Cl (where P¹ = PPh₂, P(1,3,5-Me₃C₆H₃)₂, P(2,2′-O,O′-(1,1′-biphenyl), P((R)-(2,2′-O,O′-(1,1′-binaphthyl))) and P((S)-(2,2′-O,O′-(1,1′-binaphthyl)))) followed by RX (where R = ⁿPr, ⁱPr, CHPh₂, X = Br; R = ⁱPr, X = I), respectively, gives a selection of chiral imidazolium–phosphine compounds. Deprotonation of the imidazolium salt gives the corresponding NHC–P ligands that can be used in metal-mediated asymmetric catalytic applications. Catalytic reactions show that NHC–P ligands give a significantly greater rate of reaction for a palladium catalysed allylic substitution reaction in comparison to analogous di-NHC or NHC–imine ligands and that NHC–P hybrids are also effective for iridium catalysed transfer hydrogenation.     

Reactivity of intramolecularly coordinated aluminum compounds to R3EOH (E = Sn,Si). Remarkable migration of N,C,N and O,C,O pincer ligands

The reaction of organoaluminum compounds containing O,C,O or N,C,N chelating (so called pincer) ligands [2,6-(YCH₂)₂C₆H₃]AlⁱBu₂ (Y = MeO 1, ^tBuO 2, Me₂N 3) with R₃SnOH (R = Ph or Me) gives tetraorganotin complexes [2,6-(YCH₂)₂C₆H₃]SnR₃ (Y = MeO, R = Ph 4, Y = MeO, R = Me 5; Y = ^tBuO, R = Ph 6, Y = ^tBuO, R = Me 7; Y = Me₂N, R = Ph 8, Y = Me₂N, R = Me 9) as the result of migration of O,C,O or N,C,N pincer ligands from aluminum to tin atom. Reaction of 1 and 2 with (ⁿBu₃Sn)₂O proceeded in similar fashion resulting in 10 and 11 ([2,6-(YCH₂)₂C₆H₃]SnⁿBu₃, Y = MeO 10; Y = ^tBuO 11) in mixture with ⁿBu₃SnⁱBu. The reaction 1 and 3 with 2 equiv. of Ph₃SiOH followed another reaction path and ([2,6-(YCH₂)₂C₆H₃]Al(OSiPh₃)₂, Y = MeO 12, Me₂N 13) were observed as the products of alkane elimination. The organotin derivatives 4–11 were characterized by the help of elemental analysis, ESI-MS technique, ¹H, ¹³C, ¹¹⁹Sn NMR spectroscopy and in the case 6 and 8 by single crystal X-ray diffraction (XRD). Compounds 12 and 13 were identified using elemental analysis,¹H, ¹³C, ²⁹Si NMR and IR spectroscopy.     

Thorocene adducts of the neutral 2,2′-bipyridine and its radical anion. Synthesis and crystal structures of [Th(η8-C8H8)2(κ2-bipy)] and [Th(μ-η8:η5-C8H8)2(κ2-bipy)K(py)2]∞

Thorocene [Th(Cot)₂] (Cot = η⁸-C₈H₈) readily reacts with 2,2′-bipyridine to give [Th(Cot)₂(κ²-bipy)], which has an unusual bent geometry. This compound is rapidly reduced by KC₈ into the anionic derivative [(Th(Cot)₂(κ²-bipy)]⁻. X-ray diffraction studies suggest the latter to be a Th(IV) compound with the bipyridyl radical anion. These complexes are rare examples of bent actinocene [An(Cot)₂(L)]^q− (q = 0, 1; An = actinide) and bipyridine-containing thorium species.     

New tripodal N-heterocyclic carbene chelators for small molecule activation

In an effort to develop new tripodal N-heterocyclic carbene (NHC) ligands for small molecule activation, two new classes of tripodal NHC ligands TIME^R and TIMEN^R have been synthesized. The carbon-anchored tris(carbene) ligand system TIME^R (R = Me, t-Bu) forms bi- or polynuclear metal complexes. While the methyl derivative exclusively forms trinuclear 3:2 complexes [(TIME^Me)₂M₃]³⁺ with group 11 metal ions, the tert-butyl derivative yields a dinuclear 2:2 complex [(TIME^t-Bu)₂Cu₂]²⁺ with copper(I). The latter complex shows both “normal” and “abnormal” carbene binding modes and accordingly, is best formulated as a bis(carbene)alkenyl complex. The nitrogen-anchored tris(carbene) ligands TIMEN^R (R = alkyl, aryl) bind to a variety of first-row transition metal ions in 1:1 stoichiometry, affording monomeric complexes with a protected reactivity cavity at the coordinated metal center. Complexes of TIMEN^R with Cu(I)/(II), Ni(0)/(I), and Co(I)/(II)/(III) have been synthesized. The cobalt(I) complexes with the aryl-substituted TIMEN^R (R = mesityl, xylyl) ligands show great potential for small molecule activation. These complexes activate for instance dioxygen to form cobalt(III) peroxo complexes that, upon reaction with electrophilic organic substrates, transfer an oxygen atom. The cobalt(I) complexes are also precursors for terminal cobalt(III) imido complexes. These imido complexes were found to undergo unprecedented intra-molecular imido insertion reactions to form cobalt(II) imine species. The molecular and electronic structures of some representative metal NHC complexes as well as the nature of the metal–carbene bond of these metal NHC complexes was elucidated by X-ray and DFT computational methods and are discussed briefly. In contrast to the common assumption that NHCs are pure σ-donors, our studies revealed non-negligible and even significant π-backbonding in electron-rich metal NHC complexes.     

Dialkyl- and diaryl-platinum(II) complexes with secondary phosphines: Preparation,structure and thermal reaction giving the metallopolymer

Alkyl and arylplatinum complexes with 1,5-cyclooctadiene ligand, [PtR₂(cod)] (R = Me, Ph, C₆H₄-p-CF₃, C₆F₅), react with secondary phosphines, PHR′₂ (R′ = i-Bu, t-Bu, Ph), to afford the mononuclear platinum complexes, cis-[PtR₂(PHR′₂)₂] (1a: R = Me, R′ = i-Bu; 1b: R = Me, R′ = t-Bu; 1c: R = Me, R′ = Ph; 2a: R = Ph, R′ = i-Bu; 2b: R = Ph, R′ = t-Bu; 2c: R = R′ = Ph; 3a: R = C₆H₄-p-CF₃, R′ = i-Bu; 3b: R = C₆H₄-p-CF₃, R′ = t-Bu; 3c: R = C₆H₄-p-CF₃, R′ = Ph; 4a: R = C₆F₅, R′ = i-Bu; 4c: R = C₆F₅, R′ = Ph) in 81–98% yields. Molecular structures of the complexes except for 1a, 1c and 2a were determined by X-ray crystallography. Complex 1b has a square-planar structure with Pt–C(methyl) bonds of 2.083(8) and 2.109(8) Å, while the Pt–C(aryl) bonds of 2b–c, 3a–c, 4a and 4c (2.055(1)–2.073(8) Å) are shorter than them. Thermal decomposition of 1b, 2a–c, and 3a–c releases methane, biphenyl or 4,4′-bis(trifluoromethyl)biphenyl as the organic products, which are characterized by NMR spectroscopy. The solid product of the thermal reactions of 2b and 2c were characterized as the metallopolymers formulated as [Pt(PR′₂)₂]_n (5b: R′ = ^tBu; 5c: R′ = Ph), based on the solid-state NMR and elemental analyses.     

Synthesis and crystal structure of the first chain-type nitridosilicates RE5Si3N9 (RE = La,Ce)

The novel branched chain-type nitridosilicates Ce₅Si₃N₉ and La₅Si₃N₉ have been synthesized in a radio-frequency furnace starting from the respective metals and silicon diimide Si(NH)₂ at 1625 °C for La₅Si₃N₉ and 1650 °C for Ce₅Si₃N₉, respectively. The structure of Ce₅Si₃N₉ has been determined by single-crystal X-ray diffraction (Ce₅Si₃N₉, Cmca (no. 64), a = 10.567(2) Å, b = 11.329(2) Å, c = 15.865(3) Å, V = 1899.3 Å³, Z = 8, R₁ = 0.0391, 1480 independent reflections, 90 refined parameters). The structure of isotypic La₅Si₃N₉ has been refined by the Rietveld method, starting from single-crystal data of Ce₅Si₃N₉ (La₅Si₃N₉, Cmca (no. 64), a = 10.647(4) Å, b = 11.414(4) Å, c = 16.030(5) Å, V = 1948.1 Å³, Z = 8, R_P = 0.0348, R_F² = 0.0533). Both compounds are built up of alternating Q²- and Q³-type corner sharing SiN₄ tetrahedra with additional corner sharing Q¹-units attached to the Q³-tetrahedra pointing alternately in opposing directions. These zipper-like chains are intertwined in both directions perpendicular to the chain itself to form a three-dimensionally interlocked structure with the rare-earth ions situated between the chains. Magnetic measurements resulted in a ferromagnetic ground state with a magnetic moment in agreement with Ce³⁺.     

Modelling the interaction of several bisphosphonates with hydroxyapatite using the generalised AMBER force field

The ability of the Generalised AMBER Force Field (GAFF) of Kollman and co-workers to model the structures of bisphosphonate ligands, C(R₁)(R₂)(PO₃²⁻)₂, important compounds in the treatment of bone cancer, by molecular mechanics methods is evaluated. The structure of 50 bisphosphonates and nine bisphosphonate esters were predicted and compared to their crystal structures. Partial charges were assigned from a RHF/6-31G¹ single point calculation at the geometry of the crystal structure. Additional parameters required for GAFF were determined using the methods of the force field’s developers. The structures were found to be well replicated with virtually all bond lengths reproduced to within 0.015 Å, or within 1.2σ of the crystallographic mean. Bond angles were reproduced to within 1.9° (0.8σ). The observed gauche or anti conformation of the molecules was reproduced, although in several instances gauche conformations observed in the solid state energy-minimised into anti conformations, and vice versa. The interaction of MDP (R₁ = R₂ = H), HEDP (R₁ = OH, R₂ = CH₃), APD (R₁ = OH, R₂ =  (CH₂)₂NH₃⁺), alendronate (R₁ = OH, R₂ = (CH₂)₃NH₃⁺) and neridronate (R₁ = OH, R₂ = (CH₂)₅NH₃⁺) with the (001), (010) and (100) faces of hydroxyapaptite was examined by energy-minimising 20 random orientations of each ligand 20 Å from the mineral (where there is no interaction), and then at about 8 Å from the surface whereupon the ligand relaxes onto the surface. The difference in energy between the two systems is the interaction energy. In all cases interaction with hydroxyapatite caused a decrease in energy. When modelled with a dielectric constant of 78ε_o, non-bonded interactions dominate; electrostatic interactions become important when the dielectric constant is <10ε_o. Irrespective of the value of the dielectric constant used, the structure of the ligands on the hydroxyapatite surface is very similar. On the (001) face, both phosphonate groups interact near a surface Ca²⁺ ion. The magnitude of the exothermic interaction energy varies with molecular volume (MDP<HEDP<APD<alendronate) except for neridronate which interacts less effectively than alendronate because the long amino side chain folds in on itself and does not align with the surface of the mineral. The bisphosphonates adopt two conformations on the (010) face. In the first of these, found for MDP and 40% of the alendronate structures, both phosphonates interact with the surface and the side chain points away from the surface. Hence, the interaction energy is similar for both species. In the second conformation, adopted by the majority of ligands, one phosphonate and the Cα side chain interact with the surface. The interaction energy, the magnitude of which is very similar to that on the (001) face, increases with the molecular volume of the ligand, again with the exception of neridronate. Two conformations also occur on the (100) face. In the first conformation, only one of the phosphonate groups points towards the surface and the Cα side chain interacts with the surface; in the second conformation the Cα side chain interacts strongly with the surface and both phosphonate groups point away from the surface towards the solution. The first conformation, which is the more common, is energetically more favourable. Its magnitude is virtually insensitive to the nature of the side chain and is similar to the magnitude of the interaction energy on the other two faces. The magnitude of the second conformation increases with the size of the Cα side chain.     

Synthesis and characterization of novel intramolecularly O,C,O-coordinated heteroleptic organostannylenes and their tungstenpentacarbonyl complexes

The syntheses are reported of the novel heteroleptic organostannylenes [2,6-(ROCH₂)₂C₆H₃]SnCl (1, R = Me; 2, R = t-Bu) and of their tungstenpentacarbonyl complexes [2,6-(ROCH₂)₂C₆H₃](X)SnW(CO)₅ (3, X = Cl, R = Me; 4, X = Cl, R = t-Bu; 5, X = H, R = Me). The compounds were characterized by means of elemental analyses, ¹H, ¹³C, ¹¹⁹Sn NMR spectroscopies, electrospray mass spectrometry and in case of 3 and 4 also by single crystal X-ray diffraction analysis. For the two latter compounds the substituents bound at the ether oxygen atom control the strength of intramolecular O → Sn coordination. Thus, the O–Sn distances amount to 2.391(5)/2.389(5) (3) and 2.464(3)/2.513(3) Å (4).     

Synthesis and characterization of thiosemicarbazone derivatives of 2-chloro-4-hydroxy-benzaldehyde and their rhenium(I) complexes

N-Thioamide thiosemicarbazone derived of 2-chloro-4-hydroxy-benzaldehyde (R = H, HL¹; R = Me, HL² and R = Ph, HL³) have been prepared and their reaction with fac-[ReX(CO)₃(CH₃CN)₂] (X = Br, Cl) in chloroform gave the adducts [ReX(CO)₃(HL)] (1a X = Cl, R = H; 1a′ X = Br, R = H; 1b X = Cl, R = CH₃; 1b′ X = Br, R = CH₃; 1c X = Cl, R = Ph; 1c′ X = Br, R = Ph) in good yield. Complexes 1a′ and 1b’ were also obtained by the reaction of HL¹ and HL³ with [ReBr(CO)₅] in toluene.All the compounds have been characterized by elemental analysis, mass spectrometry (FAB), IR and ¹H NMR spectroscopic methods. Moreover, the structures of HL², HL³ and 1a·H₂O were also established by X-ray diffraction. In 1a, the rhenium atom is coordinated by the sulphur and the azomethine nitrogen atoms, forming a five-membered chelate ring, as well as three carbonyl carbon and chloride atoms. The resulting coordination polyhedron can be described as a distorted octahedron.The study of the crystals obtained by slow evaporation of methanol and DMSO solutions of the adducts 1a′ and 1b, respectively, showed the formation of dimer structures based on rhenium(I) thiosemicarbazonates [Re₂(L¹)₂(CO)₆]·3H₂O (2a)·3H₂O and [Re₂(L²)₂(CO)₆]·(CH₃)₂SO (2b)·2(CH₃)₂SO. Amounts of these thiosemicarbazonate complexes [Re₂(L)₂(CO)₆] (2) were obtained by reaction of the corresponding free ligands with [ReCl(CO)₅] in dry toluene.In 2a·3H₂O and 2b·2(CH₃)₂SO the dimer structures are established by Re–S–Re bridges, where S is the thiolate sulphur from a N,S-bidentate thiosemicarbazonate ligand. In both structures the rhenium coordination sphere is similar; the dimers are in the same diamond Re₂S₂ face.     

Molecular switching complexes with iron and tin as central atom

The precursor [Fe^III(L)Cl] (LH₂ = N,N′-bis(2′-hydroxy-benzyliden)-1,6-diamino-3-N-hexane is a high-spin (S = 5/2) complex. This precursor is combined with the bridging units [Sn^IV(X)₄] (X = CN^?, NCS^?) to yield star-shaped pentanuclear clusters, [(LFe^III–X)₄Sn]Cl₄. For X = CN^? the ⁵⁷Fe-Mössbauer data show a multiple spin transition between iron(III) in the high-spin and low-spin state, while the ^119mSn-Mössbauer data indicate a valence tautomerism between Sn(IV) and Sn(II). Changing the bridging unit from X = CN^? to X = NCS^? turns the switchability off.     

Synthesis and structure of a new scorpionate-dithio carboxyl oxovanadium complex and an organic dithio carboxyl compound

A new complex of oxovanadium(IV), V₂O₂[(HB(pz)₃)₂(pyrro)₂ (1) and a dimer-dithio carboxyl compound (C₅H₈NS₂)₂ (2) have been synthesized by the reaction of VOSO₄·nH₂O with NaHB(pz)₃ and pyrrolidine dithio carboxylic acid ammonium salt. They were characterized by element analysis, IR spectra, UV–vis spectra and X-ray diffraction. Structural analyses of 1 and 2 gave the following parameters: 1, triclinic, P-1, a = 7.732(4) Å, b = 14.285(8) Å, c = 17.802(9) Å, α = 101.314(8)°, β = 92.682(9)°, γ = 92.228(9)°, V = 1923.6(18) Å³, and Z = 4; 2, monoclinic, C2/c, a = 13.857(2) Å, b = 10.4213(18) Å, c = 9.436(2) Å, β = 97.099(2), V = 1352.1(4) Å³, and Z = 4. In complex 1, vanadium atom adopts a distorted tetragonal bipyramid structure, which is typical for oxovanadium(IV) complexes. Compound 2 is a dimer-dithio carboxyl compound with S–S bond. In addition, thermal analysis was performed for analyzing the stabilization of the complexes.     

Standard Gibbs energy of formation of platinic acid H2Pt(OH) 6in the crystalline state

Heat capacity of platinic acid, hydrogen hexahydroxyplatinate(IV)H₂Pt(OH)₆ , was measured from T =  7 K toT =  310 K by means of adiabatic calorimetry. The standard entropy and the standard Gibbs energy of formation of platinic acid in the crystalline state were determined to be 176.5  ±  3.6 J · K ^− 1· mol ^− 1and  − 988.8  ±  3.8 kJ · mol ^− 1, respectively.     

Crystal chemistry and physical properties of the ternary compounds REBC (RE = Ce,Pr, Nd)

The ternary rare-earth metal boride carbides REBC (RE = Ce, Pr, Nd) were prepared by melting mixtures of the elements and subsequent annealing at temperatures between 1270 K and 1570 K. Their crystal structures were refined from single crystal X-ray diffraction data. They crystallize in the LaBC-type structure (space group P2₁2₁2₁, Z = 20); CeBC: a = 8.5021(5) Å, b = 8.5217(7) Å, c = 12.3834(7) Å, R1 = 0.033 (wR2 = 0.059) for 2838 reflections with I_o > 2σ(I_o); PrBC: a = 8.4478(5) Å, b = 8.4719(8) Å, c = 12.325(1) Å, R1 = 0.031 (wR2 = 0.063) for 2564 reflections with I_o > 2σ(I_o); NdBC: a = 8.370(1) Å, b = 8.392(1) Å, c = 12.253(3) Å, R1 = 0.035 (wR2 = 0.086) for 4275 reflections with I_o > 2σ(I_o). The structure consists of a three-dimensional framework of rare-earth metal atoms resulting from the stacking of slightly corrugated two-dimensional square nets, leading to voids filled with B₅C₅ finite chains. The magnetism of the compounds PrBC and NdBC is characterized by the onset of ferromagnetism with Curie temperatures around 10 K and 8 K, respectively. The reduced effective paramagnetic moment μ_eff ≈ 1.8 μ_B as well as the weak magnetization at 6 K, 5 T is discussed.     

Spontaneous resolution of a novel chiral coordination polymer through supramolecular interactions and solvent symmetry breaking

The spontaneous resolution reaction of racemic trans-2,3-dihydro-2,3-dipyridyl-benzo[e]indole 1 with Cd(ClO₄)₂·6H₂O in the presence of 2-butanol under solvothermal reaction conditions favors the formation of crystal 2 [P-Cd(R,R,-1)₂(ClO₄)₂], while a similar reaction in the presence of ethanol only favors the formation of crystal 3 [M-Cd(S,S,-1)₂(ClO₄)₂]. The crystal structural determination shows that both 2 and 3 crystallize in chiral enantiomorphous space groups (P6₁22 and P6₅22) and their structures are 1D infinite chain, and are just enantiomorphous pairs most like. The spontaneous resolution process displays estimated ee values of ca. +0.6 for 2-butanol and ca. −0.4 for ethanol. Enantiomerically pure (S,S)-trans-2,3-dihydro-2,3-dipyridyl-benzo[e]indole (S,S,-1) can be obtained through the decomposition of mechanically separated 3. Additionally (S,S,-1) also crystallizes in a chiral space group (P2₁). The CD (circular dichroism) spectra of both 2 and 3 in the solid state are also approximately enantiomorphous pairs. However, their fluorescent spectra in the solid state display a moderate difference in maximum emission peaks (Δλ = 19 nm). Crystal data for 2: C₄₄H₃₄Cl₂N₆O₈Cd, M = 958.07, hexagonal, P6₁22, a = 10.5488(5), c = 68.256(4) Å, α = γ = 90°, β = 120°, V = 6577.8(6) Å³, Z = 6, D_c = 1.451 mg m⁻³, R₁ = 0.0498, wR₂ = 0.1124, μ = 0.679 mm⁻¹, S = 0.623, Flack χ = −0.02(6). For space group P6₅22, R₁ = 0.0670, wR₂ = 0.1602, S = 0.725 with a Flack value of 1.03(7); Crystal data for 3, C₄₄H₃₄Cl₂N₆O₈Cd, M = 958.07, hexagonal, P6₅22, a = 10.5446(3), c = 68.265(3) Å, V = 6573.3(4) Å³, Z = 6, D_c = 1.452 mg m⁻³, R₁ = 0.0444,wR₂ = 0.1002, μ = 0.679 mm⁻¹, S = 0.558, Flack χ = 0.01(5). For space group P6₁22, R₁ = 0.0501, wR₂ = 0.1178, S = 0.599 with a Flack value of 1.00(5). The low Flack parameter indicates that the absolute configurations of 2 and 3 are stated; Crystal data for (S,S)-1, C₂₂H₁₇N₂, M = 323.39, orthorhombic, P2₁2₁2₁, a = 9.2598(7), b = 9.4617(8), c = 19.1452(16) Å, V = 1677.4(2) Å³, Z = 4, D_c = 1.281 mg m⁻³, R₁ = 0.0417, wR₂ = 0.1191, T = 293 K, μ = 0.077 mm⁻¹, S = 0.862.     

Synthesis,characterization and antibacterial activity of some new triphenyltin(IV) sulfanylcarboxylates: Crystal structure of [(SnPh3)2(p-mpspa)], [(SnPh3)2(cpa)] and [(SnPh3)2(tspa)(DMSO)]

Five new triphenyltin(IV) sulfanylcarboxylates of the general formula [(SnPh₃)₂L] (L = pspa, tspa, fspa, p-mpspa or cpa, where p = 3-(2-phenyl)-, t = 3-(2-thienyl)-, f = 3-(2-furyl)-, p-mp = 3-(4-methoxyphenyl)-, spa = 2-sulfanylpropenoato and cpa = 2-cyclopentilyden-2-sulfanylacetate) have been synthesized by reacting triphenyltin(IV) hydroxide with the corresponding acid in ethanol/acetone. The complexes have been characterized by elemental analysis and mass spectrometry and by vibrational and NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopies. In the case of [(SnPh₃)₂(p-mpspa)] and [(SnPh₃)₂(cpa)], X-ray structural studies showed that in both compounds each Sn atom is coordinated to three phenyl C atoms and to one S or O atom of the bridge ligand L. All five complexes are active against strains of Staphylococcus aureus, but are inactive against Escherichia coli and Pseudomonas aeruginosa. From a solution of [(SnPh₃)₂(tspa)] in DMSO-d₆ the new complex [(SnPh₃)₂(tspa)(DMSO)] was isolated. The single-crystal X-ray diffractometric study of this complex is also reported, showing that both Sn atoms are bridged by the tspa ligand, whereas the molecule of DMSO is coordinated to one of the tin atoms via the oxygen atom.