Kinetics and mechanism of the chromic oxidation of 3-O-methyl-d-glucopyranose

The oxidation of 3-O-methyl-d-glucopyranose (Glc3Me) by Cr^VI in acid medium yields Cr^III, formic acid and 2-O-methyl-d-arabinose as final products when a 50-times or higher excess of Glc3Me over Cr^VI is used. The redox reaction takes place through the combination of Cr^VI → Cr^IV → Cr^II and Cr^VI → Cr^IV → Cr^III pathways. Intermediacy of free radicals and Cr^II in the reaction was demonstrated by the observation of induced polymerization of acrylamide and detection of CrO₂²⁺ formed by reaction of Cr^II with O₂. Intermediate oxo-Cr^V–Glc3Me species were detected by EPR spectroscopy. In 0.3–0.5 mol/L HClO₄, intermediate Cr^V rapidly decompose to the reaction products, while, at pH 5.5–7.5, where the redox processes are very slow, five-coordinate Cr^V bis-chelates of the pyranose and furanose forms of Glc3Me remain more than 15 h in solution. The C1–C2 bond cleavage of Glc3Me upon reaction with Cr^VI distinguishes this derivative from glucose, which is oxidized to gluconic acid.     

New ionic liquid for inorganic cations analysis by capillary electrophoresis: 2-hydroxy- N , N , N -trimethyl-1-phenylethanaminium bis(trifluoromethylsulfonyl)imide (phenylcholine NTf2)

The potentialities of new ionic liquids (ILs) based on choline were evaluated as an electrophoretic medium in capillary electrophoresis for the analysis of alkaline and alkaline earth cations (Li⁺, K⁺, Na⁺, Cs⁺, Mg²⁺, Ba²⁺, Ca²⁺, and Sr²⁺) with indirect UV detection. Two types of capillaries were tested: an untreated fused silica and fused silica coated with a film of polyvinylalcohol. The coated capillary proved to be the best adapted for the metal ions studied. Moreover, it appeared that the nature of the ionic liquid anion influenced the baseline stability, and the bis(trifluoromethylsulfonyl) imide (NTf₂ ⁻) anion seemed to be the most efficient. These preliminary studies led us to synthesize a new ionic liquid, 2-hydroxy-N,N,N-trimethyl-1-phenylethanaminium NTf₂ (phenylcholine NTf₂). This liquid was able to act as the running electrolyte and probe, generating the background signal in indirect UV light and consequently simplifying the electrophoretic medium. Excellent baseline stability, good reproducibility, as well as good sensitivity of detection were obtained with this new ionic liquid. Thus, 510,000 plates/meter for Li⁺ with 40 mM IL were successfully obtained. The optimal concentration of IL was 20 mM with a detection limit ranging from 28 μg L⁻¹ for Li⁺ to 1,000 μg L⁻¹ for Cs⁺. This method (phenylcholine NTf₂ with polyvinylalcohol capillary) was applied to analyze different commercial source and mineral waters. Finally, the potentiality of this ionic liquid in nonaqueous capillary electrophoresis was explored. The use of phenylcholine NTf₂ with a fused silica capillary, in pure methanol medium and in the presence of acetic acid, made it possible to obtain separation selectivity different from that obtained in aqueous medium.     

B-frame supported bimetallics. [(PMe2ph)2PtB9H11Ru(η-PrC6H4Me)] and [(PMe2ph)2PtB9H9Ru(η-PrC6H4Me)]; an interesting pair of electron-deficient nido and closo geometries

[7,7-(PMe₂Ph)₂-9-(η⁶-^isoPrC₆H₄Me)-7,9-PtRuB₉H₁₁] has a formal closo Wadian cluster-electron count, but a nido geometry, whereas [1-(η⁶-^isoPrC₆H₄Me)-4,4-(PMe₂Ph)₂-1-4-RuPtB₉H₉], which does have a closo geometry, has a formal sub-closo cluster electron count; both compounds are formed in the reaction between [6-(η⁶-^isoPrC₆H₄Me)-nido-6 RuB₉H₁₃], KH and [PtCl₂(PMe₂Ph)₂].     

Preparation, properties, and reactivity of carbonylrhodium(I) complexes of di(2-pyrazolylaryl)amido-pincer ligands

A series of six carbonylrhodium(I) complexes of three new and three previously reported di(2-3R-pyrazolyl)-p-Z/X-aryl)amido pincer ligands, (^RZX)Rh(CO), (R is the substituent at the 3-pyrazolyl position proximal to the metal; Z and X are the aryl substituents para- to the arylamido nitrogen) were prepared. The metal complexes were studied to assess how their properties and reactivities can be tuned by varying the groups along the ligand periphery and how they compared to other known carbonylrhodium(I) pincer derivatives. This study was facilitated by the discovery of a new CuI-catalyzed coupling reaction between 2-(pyrazolyl)-4-X-anilines (X = Me or CF₃) and 2-bromoaryl-1H-pyrazoles that allow the fabrication of pincer ligands with two different aryl arms. The NNN-pincer scaffolds provide an electron-rich environment for the carbonylrhodium(I) fragment as indicated by carbonyl stretching frequencies that occur in the range of 1948-1968 cm⁻¹. As such, the oxidative addition (OA) reactions with iodomethane proceed instantaneously to form trans-(NNN-pincer)Rh(Me)(CO)(I) in room temperature acetone solution. The OA reactions with iodoethane proceeded at a convenient rate in acetone near 45 °C which allowed detailed kinetic studies. The relative order of reactivity was found to be (CF₃CF₃)Rh(CO) < (^iPrMeMe)Rh(CO) < (^MeMeMe)Rh(CO) ∼ (CF₃Me)Rh(CO) < (MeH)Rh(CO) < (MeMe)Rh(CO) with the second order rate constant of the most reactive in the series, k₂ = 8 × 10⁻³ M⁻¹ s⁻¹, being about three orders of magnitude greater than those reported for [Rh(CO)₂I₂]⁻ or CpRh(CO)(PPh₃). After oxidative addition, the resultant rhodium(III) complexes were found to be unstable. Although a few trans-(^RMeMe)Rh(E = Me, Et, or I)(CO)(I) could be isolated in pure form, all were found to slowly decompose in solution to give different products depending on the 3R-pyrazolyl substituents. Those with unsubstituted pyrazolyls (R = H) decompose with CO dissociation to give insoluble dimeric [(^RMeMe)Rh(E)(μ-I)]₂ while those with 3-alkylpyrazolyls (R = Me, ⁱPr) decompose to give soluble, but unidentified products.     

Effect of various oxidants in a photocatalysis/filtration system for the treatment of contaminants

This study was conducted to investigate the effect of a photocatalysis/oxidant system for the treatment of humic acid and hazardous heavy metals in aqueous solutions. Hydrogen peroxide, ozone, and potassium peroxodisulfate were tested as oxidants. The effect of oxidant concentration was conducted with a pH of 7, a UV intensity of 64 W, and a TiO₂ dosage of 0.3 g L⁻¹. The oxidant addition in the UV/TiO₂ system enhanced the degradation efficiency of humic acid and hazardous heavy metals compared to no addition of an oxidant. The addition of oxidants over the amounts of H₂O₂ 50 mg L⁻¹, O₃ 20 g m⁻³, and K₂S₂O₈ 50 mg L⁻¹ inhibits the system efficiency. The negative effect of higher oxidant concentrations likely results from OH radical quenching caused by the excess oxidant. Therefore, the optimal dosages of oxidants such as a hydrogen peroxide, ozone, and potassium peroxodisulfate were found to be 50 mg L⁻¹, 20 g m⁻³, and 50 mg L⁻¹, respectively. The degradation efficiency of UV/TiO₂/oxidant systems for the removal of humic acid and hazardous heavy metals was much greater in the UV/TiO₂/H₂O₂ system using H₂O₂ as an oxidant.     

Triethylantimony(V) complexes with bidentate O,N-, O,O- and tridentate O,N,O′-coordinating o-iminoquinonato/o-quinonato ligands: Synthesis, structure and some properties

The novel triethylantimony(v) o-amidophenolato (AP-R)SbEt₃ (R = i-Pr, 1; R = Me, 2) and catecholato (3,6-DBCat)SbEt₃ (3) complexes have been synthesized and characterized by IR, NMR spectroscopy (AP-R is 4,6-di-tert-butyl-N-(2,6-dialkylphenyl)-o-amidophenolate, alkyl = isopropyl (1) or methyl (2); 3,6-DBCat is 3,6-di-tert-butyl-catecholate). Complexes 1–3 have been obtained by the oxidative addition of corresponding o-iminobenzoquinones or o-benzoquinones to Et₃Sb. The addition of 4,6-di-tert-butyl-N-(3,5-di-tert-butyl-2-hydroxyphenyl)-o-iminobenzoquinone to Et₃Sb at low temperature gives hexacoordinate [(AP-AP)H]SbEt₃ (4) which decomposes slowly in vacuum with the liberation of ethane yielding pentacoordinate complex [(AP-AP)]SbEt₂ (5). [(AP-AP)H]²⁻ is O,N,O′-tridentate amino-bis-(3,5-di-tert-butyl-phenolate-2-yl) dianion and [(AP-AP)]³⁻ is amido-bis-(3,5-di-tert-butyl-phenolate-2-yl) trianion. The decomposition of 4–5 accelerates in the presence of air. o-Amidophenolates 1 and 2 bind molecular oxygen to give spiroendoperoxides Et₃Sb[L-iPr]O₂ (6) or Et₃Sb[L-Me]O₂ (7) containing trioxastibolane rings. This reaction proceeds slowly and reaches the equilibrium at 15–20% conversion five times more than for (AP-R)SbPh₃ analogues. Molecular structures of 1 and 5 were determined by X-ray analysis.     

The sorption of Eu(III) on calcareous soil: effects of pH,ionic strength,temperature, foreign ions and humic acid

The sorption of Eu(III) on calcareous soil as a function of pH, humic acid (HA), temperature and foreign ions was investigated under ambient conditions. Eu(III) sorption on soil was strongly pH dependent in the observed pH range. The effect of ionic strength was significant at pH < 7, and not obvious at pH > 8. The type of salt cation used had no visible influence on Eu(III) uptake on soil, however at low pH values, the influence of anions was following the order: Cl⁻ ≈ NO₃ ⁻ > ClO₄ ⁻. In the presence of HA, the sorption edge obviously shifted about two pH units to the lower pH, whilst in range of pH 6–7, the sorption of Eu(III) decreased with increasing pH because a considerable amount of Eu(III) was present as humate complexes in aqueous phase, then increased again at pH > 11. The results indicated that the sorption of Eu(III) on soil mainly formed outer-sphere complexes and/or ion exchange below pH ~7; whereas inner-sphere complexes and precipitation of Eu(OH)₃(s) may play main role above pH ~8.     

Iron(II) and cobalt(II) complexes bearing 8-(1-aryliminoethylidene) quinaldines: Synthesis, characterization and ethylene dimerization behavior

The series of bidentate N^N iron(II) and cobalt(II) complexes containing 8-(1-aryliminoethylidene) quinaldine derived ligands, 8-[2,6-(R¹)₂-4-R²-C₆H₂NC (Me)]-2-Me-C₁₀H₅N, were synthesized and characterized by elemental and spectroscopic techniques. The molecular structures of Co1 (R¹ = Me, R² = H), Co3 (R¹ = ⁱPr, R² = H) and Co4 (R¹ = R² = Me) were confirmed as the distorted tetrahedral by single crystal X-ray diffraction. On treatment with modified methylaluminoxane (MMAO), these complexes exhibited good catalytic activities of up to 5.71 × 10⁵ g mol⁻¹(Fe) h⁻¹ for the ethylene dimerization at 30 °C under 10 atm of ethylene, in which iron pre-catalysts produced butenes with a high selectivity for α-butene. The correlation between metal complexes, catalytic activities and the product formed were investigated under various reaction parameters.     

Formation, structure and magnetism of the metastable defect fluorite phases AVO3.5+x (A=In, Sc)

We report the preparation and stability of ScVO_3.5+x and the novel phase InVO_3.5+x. AVO_3.5+x (A=Sc, In) defect fluorite structures are formed as metastable intermediates during the topotactic oxidation of AVO₃ bixbyites. The oxidation pathway has been studied in detail by means of thermogravimetric/differential thermal analysis and in-situ powder X-ray diffraction. The oxidation of the bixbyite phase follows a topotactic pathway at temperatures between 300 and 400 °C in air/carbon dioxide. The range of accessible oxygen stoichiometries for the AVO_3.5+x structures following this pathway are 0.00x0.22. Rietveld refinements against powder X-ray and neutron data revealed that InVO_3.54 and ScVO_3.70 crystallize in the defect fluorite structure in space group Fm-3 m (227) with a=4.9863(5) and 4.9697(3)Å, respectively with A³⁺/V⁴⁺ disorder on the (4a) cation site. Powder neutron diffraction experiments indicate clustering of oxide defects in all samples. Bulk magnetic measurements showed the presence of V⁴⁺ and the absence of magnetic ordering at low temperatures. Powder neutron diffraction experiments confirmed the absence of a long range ordered magnetic ground state.     

Europium (III) and Uranium (VI) complexation by natural organic matter (NOM): Effect of source

For the safe long‐term storage of high‐level radioactive waste (HLW), detailed information about geo‐chemical behavior of radioactive and toxic metal ions under environmental conditions is important. Natural organic matter (NOM) can play a crucial role in the immobilization or mobilization of these metal ions due to its complexation and colloid formation tendency. In this study, the complexation of europium (as chemical homologue of trivalent actinides such as americium) and uranium (as main component of HLW) by ten humic acids (HA) from different sources and Suwannee NOM river extract has been analyzed. Capillary electrophoresis in combination with inductively coupled plasma mass spectrometry has been used for the evaluation of complex stability constants log β. In order to determine the complex stability constants a conservative single site model was used in this study. In dependence of their source and thus of NOM structure the log β values for the analyzed humic acids are in the range of 6.1–7.0 for Eu(III) and 5.2–6.4 for U(VI) (UO₂²⁺), respectively. In contrast to the results for HA the used Suwannee river NOM reveals log β values in the range of nearly two orders of magnitude lower (4.6 for Eu³⁺ and 4.5 for UO₂²⁺) under the geochemical conditions applied in this study.     

Ketiminate supported aluminum(III) complexes: Synthesis, characterization and reactivity

The reaction of LLi, (L = [RNC(Me)CHC(Me) = O] (R = C₂H₄NEt₂)), with AlCl₃ at −78 °C forms the mono-ketiminate product, LAlCl₂, 1, while the same reaction at 0 °C affords the bis-ketiminate complex, [{(LH)₂AlCl}(Cl₂)], 2, Reduction of 1 with Li^o, K^o or Mg^o yielded an unusual dimeric aluminum(III) species, [L′AlCl]₂, 3, where C-C coupling of the ligand backbone is observed.     

In search for mixed transition metal/lanthanide single-molecule magnets: Synthetic routes to NiII/TbIII and NiII/DyIII clusters featuring a 2-pyridyl oximate ligand

Employing the mononuclear complex [Ni{(py)C(Me)NO}₂{(py)C(Me)NOH}] (1) as ‘ligand’ [(py)C(Me)NOH = methyl 2-pyridyl ketone oxime], the use of the ‘metal complexes as ligands’ approach has led to the synthesis of the mixed Ni^II/Ln^III complexes [NiTb{(py)C(Me)NO}₂(NO₃)₃{(py)C(Me)NOH}] (2), [Ni₂Ln₂{(py)C(Me)NO}₆(NO₃)₄] (Ln = Dy, 3; Ln = Tb, 4) and [Ni₂Tb{(py)C(Me)NO}₆](NO₃) (5). The structures of 2, 3, and 5, and the magnetic properties of 2 and 5 are briefly discussed.     

A 3D porous indium(III) coordination polymer involving in-situ ligand synthesis

The hydrothermal reaction of In³⁺ and 1,2,4-benzenetricarboxylic acid with the presence of piperazine leads to the generation of a novel 3D porous coordination polymer, [H₃O][In₂(btc)(bdc)(OH)₂]·5.5H₂O (1), (btc=1,2,4-benzenetricarboxylate, bdc=1,4-benzenedicarboxylate). Compound 1 crystallizes in orthorhombic space group Pbca with a=16.216(7) Å, b=13.437(6) Å, c=31.277(14) Å, and Z=8. It is interesting to find that the in-situ decarboxylation reaction of 1,2,4-benzenetricarboxylate (btc) partially transformed into 1,4-benzenedicarboxylate (bdc) occurs. The 16 indium(III) centers were linked by four btc, four bdc and two μ₂-OH ligands to form a box-girder. The adjacent box-girders are further connected by the bdc and btc ligands to generate a novel porous metal–organic framework containing nanotubular open channel with a cross-section of approximately 11.5×11.3 Å². The micropores are occupied by lattice water molecules, and the solvent-accessible volume of the unit cell was estimated to be 3658.6 Å³, which is approximately 53.7% of the unit-cell volume (6815.4 Å³).     

Preparation of new dinuclear half-titanocene complexes with ortho- and meta-xylene linkages and investigation of styrene polymerization

Half-titanocene is well-known as an excellent catalyst for the preparation of SPS (syndiotactic polystyrene) when activated with methylaluminoxane (MAO). Dinuclear half-sandwich complexes of titanium bearing a xylene bridge, (TiCl₂L)₂{(μ-η⁵, η⁵-C₅H₄-ortho-(CH₂–C₆H₄–CH₂)C₅H₄}, (4 (L = Cl), 7 (L = O-2,6-iPr₂C₆H₃)) and (TiCl₂L)₂{(μ-η⁵, η⁵-C₅H₄-meta-(CH₂–C₆H₄–CH₂)C₅H₄} (5 (L = Cl), 8(L = O-2,6-iPr₂C₆H₃)), have been successfully synthesized and introduced for styrene polymerization. The catalysts were characterized by ¹H- and ¹³C NMR, and elemental analysis. These catalysts were found to be effective in forming SPS in combination with MAO. The activities of the catalysts with rigid ortho- and meta-xylene bridges were higher than those of catalysts with flexible pentamethylene bridges. The catalytic activity of four dinuclear half-titanocenes increased in the order of 4 < 5 < 7 < 8. This result displays that the meta-xylene bridged catalyst is more active than the ortho-xylene bridged and that the aryloxo group at the titanium center is more effective at promoting catalyst activity compared to the chloride group at the titanium center. Temperature and ratio of [Al]:[Ti] had significant effects on catalytic activity. Polymerizations were conducted at three different temperatures (25, 40, and 70 °C) with variation in the [Al]:[Ti] ratio from 2000 to 4000. It was observed that activity of the catalysts increased with increasing temperature, as well as higher [Al]:[Ti]. Different xylene linkage patterns (ortho and meta) were recognized to be a principal factor leading to the characteristics of the dinuclear catalyst due to its different spatial arrangement, causing dissimilar intramolecular interactions between the two active sites.     

Synthesis and characterization of Pd(IMe)2, and its reactivity by C-S oxidative addition of DMSO

Two-electron reduction of PdX₂(NHC)₂ with Groups 1, 2 metals (K, Mg) is a convenient route to Pd(NHC)₂ complexes including Pd(IMe)₂ (2a), isolated and crystallographically characterized as the least sterically encumbered d¹⁰ M(0)L₂ species to date. 2a exhibits a regular linear geometry and modest Lewis acidity to coordinating solvents and additional IMe. In contrast to its analogs with bulkier NHC = I^tBu and IPr, 2a undergoes cleanly net oxidative addition of the Me-S(O)Me bond of DMSO, forming trans-PdMe(S(O)Me)IMe₂ (3) at RT. DFT calculations suggest this reaction to proceed by substitution of IMe by κS-DMSO followed by concerted C-S oxidative addition to Pd with a single IMe, with a preference of ca. 10 kcal/mol in the effective ΔG_s^‡ over the direct pathway. Calculations also identify two facile intramolecular pathways for racemization of Pd(II) methylsulfinyl complexes at sulfur.     

Accumulation of Exopolysaccharides in Liquid Suspension Culture of Nostoc flagelliforme Cells

The liquid suspension culture of dissociated Nostoc flagelliforme cells was investigated. It was found that the growth rate of N. flagelliforme cells and the accumulation of exopolysaccharides (EPS) increased prominently when NaNO₃ and KH₂PO₄ were added in the liquid BG-11culture medium though phosphate had little effect on EPS yield for specific mass of cells. N. flagelliforme cells grew well at 25 °C and neutral pH, however, a lower or higher temperature and weak alkaline can promote EPS accumulation. With the increase of the light intensity, the growth rate of N. flagelliforme cells and the EPS accumulation increase accordingly. When N. flagelliforme cells was cultured in BG-11 medium added with 2.5 g L⁻¹ of NaNO₃ and 0.956 g L⁻¹ of KH₂PO₄ at 25 °C with 60 μmol photon m⁻² s⁻¹ of light intensity, 1.05 g L⁻¹ cell density and 89.9 mg L⁻¹ EPS yield were achieved respectively. Adopting the optimal conditions established in flask culture, the liquid culture of N. flagelliforme cells in 20-L photobioreactor for 16 days was conducted and a maximum biomass of 1.32 g L⁻¹ was achieved, which was about 17.6-fold of that in the initial inoculation. The yield of EPS was 228.56 mg L⁻¹and about 2.23-fold of that in flask culture. Moreover, the polysaccharides’ material was released into the culture medium during cell growth. These released polysaccharides (RPSs), which can be easily recovered from the medium, are favorable for industrial applications.     

The influence of humic acid on the pH-dependent sorption of americium(III) onto kaolinite

This work investigates the sorption of americium [Am(III)] onto kaolinite and the influence of humic acid (HA) as a function of pH (3–11). It has been studied by batch experiments (V/m = 250:1 mL/g, C _Am(III) = 1 × 10⁻⁵ mol/L, C _HA = 50 mg/L). Results showed that the Am(III) sorption onto the kaolinite in the absence of HA was typical, showing increases with pH and a distinct adsorption edge at pH 3–5. However in the presence of HA, Am sorption to kaolinite was significantly affected. HA was shown to enhance Am sorption in the acidic pH range (pH 3–4) due to the formation of additional binding sites for Am coming from HA adsorbed onto kaolinite surface, but reduce Am sorption in the intermediate and high pH above 6 due to the formation of aqueous Am-humate complexes. The results on the ternary interaction of kaolinite–Am–HA are compared with those on the binary system of kaolinite–HA and kaolinite–Am and adsorption mechanism with pH are discussed. Effect of different molecular weight of HA, with three HA fractions separated by ultrafiltration techniques, on the Am sorption to kaolinite were also studied. The results showed that the enhancement of the sorption of Am onto kaolinite at the acidic pH conditions (pH 3–4) was higher with HA fractions of higher molecular weight. Also, the Am sorption over a pH range from 6 to 10 decreased with decreasing molecular weight of HA.     

Degradation of n-butylparaben and 4-tert-octylphenol in H2O2/UV system

The degradation of two endocrine disrupting compounds: n-butylparaben (BP) and 4-tert-octylphenol (OP) in the H₂O₂/UV system was studied. The effect of operating variables: initial hydrogen peroxide concentration, initial substrate concentration, pH of the reaction solution and photon fluency rate of radiation at 254 nm on reaction rate was investigated. The influence of hydroxyl radical scavengers, humic acid and nitrate anion on reaction course was also studied. A very weak scavenging effect during BP degradation was observed indicating reactions different from hydroxyl radical oxidation. The second-order rate constants of BP and OP with OH radicals were estimated to be 4.8×10⁹ and 4.2×10⁹ M^?1 s^?1, respectively. For BP the rate constant equal to 2.0×10¹⁰ M^?1 s^?1was also determined using water radiolysis as a source of hydroxyl radicals.     

Influence of biomass and gold salt concentration on nanoparticle synthesis by the tropical marine yeast Yarrowia lipolytica NCIM 3589

Cell-associated gold nanoparticles and nanoplates were produced when varying number of Yarrowia lipolytica cells were incubated with different concentrations of chloroauric acid (HAuCl₄) at pH 4.5. With 10⁹ cells ml⁻¹ and 0.5 or 1.0 mM of the gold salt, the reaction mixtures developed a purple or golden red colour, respectively, and gold nanoparticles were synthesized. Nanoparticles of varying sizes were produced when 10¹⁰ cells ml⁻¹ were incubated with 0.5, 1.0 or 2.0 mM chloroauric acid salt. With 3.0, 4.0 or 5.0 mM HAuCl₄, nanoplates were also observed. With 10¹¹ cells ml⁻¹ nanoparticles were synthesized with almost all the gold salt concentrations. The cell-associated particles were released outside when nanoparticle-loaded cells were incubated at low temperature (20 °C) for 48 h. With increasing salt concentrations and a fixed number of cells, the size of the nanoparticles progressively increased. On the other hand, with increasing cell numbers and a constant gold salt concentration, the size of nanoparticles decreased. These results indicate that by varying the number of cells and the gold salt concentration, a variety of nanoparticles and nanoplates can be synthesized. Fourier transform infrared (FTIR) spectroscopy revealed the possible involvement of carboxyl, hydroxyl and amide groups on the cell surfaces in nanoparticle synthesis.     

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).