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A stable ionic κ2Sn,P-coordinated Ru complex shows excellent catalytic activity in aerobic oxidations of benzylamine and benzyl alcohol. This complex is stabilized by a stannylene-phosphine peri-substituted naphthalene ligand, which can act as either a reducing agent for a Ru(III) complex or as a κ2Sn,P-chelating ligand for Ru(II) compounds.

Alpha-Iminopyridine ligands L-1(2-(CH=N(C6H2-2,4,6-Ph-3))C5H4N), L-2 (2-(CH=N(C6H2-2,4,6-tBu(3)))C5H4N) and L-3 (1,2-(C5H4N-2-CH=N)(2)CH2CH2) differing by the steric demand of the substituent on the imine CH=N group and by the number of donating nitrogen atoms were utilized to initiate a Lewis base mediated ionization of SnCl2 in an effort to prepare ionic tin(II) species [L1-3 -> SnCl][SnCl3]. The reaction of L-1 and L-2 with SnCl2 led to the formation of neutral adducts [L-1 -> SnCl2] (2) and [L-2 -> SnCl2] (3). The preparation of the desired ionic compounds was achieved by subsequent reactions of 2 and 3 with an equivalent of SnCl2 or GaCl3. In contrast, ligand L-3 containing four donor nitrogen atoms showed the ability to ionize SnCl2 and also Sn(OTf)(2), yielding [L-3 -> SnCl][SnCl3] (7) and [L-3 -> Sn(H2O)][OTf](2) (8). The study thus revealed that the reaction is dependent on the type of the ligand. The prepared complexes 4-8 together with the previously reported [{2-((CH3)C=N(C6H3-2,6-iPr(2)))-6-CH3O-C5H3N}SnCl][SnCl3] (1) were tested as catalysts for the ROP of L-lactide, which could operate via an activated monomer mechanism. Finally, a DFT computational study was performed to evaluate the steric and electronic properties of the ionic tin(II) species 1 and 4-8 together with their ability to interact with the L-lactide monomer. Alfa-iminopyridinové ligandy L-1(2-(CH=N(C6H2-2,4,6-Ph-3))C5H4N), L-2 (2-(CH=N(C6H2-2,4,6- tBu(3)))C5H4N) a L-3 (1,2-(C5H4N-2-CH=N)(2)CH2CH2) lišící se stericitou substituentu na iminové skupině CH=N a počtem donorových atomů dusíku byly použity k autoionizaci SnCl2 zprostředkované Lewisovou bází ve snaze připravit cínaté iontové komplexy [L1-3 -> SnCl][SnCl3]. Reakce L-1 a L-2 se SnCl2 vedla ke vzniku neutrálních aduktů [L-1 -> SnCl2] (2) a [L-2 -> SnCl2] (3). Příprava požadovaných iontových sloučenin byla dosažena následnými reakcemi s ekvivalentem SnCl2 nebo GaCl3. Naproti tomu ligand L-3 obsahující čtyři donorové atomy dusíku vykazoval schopnost ionizovat SnCl2 a také Sn(OTf)(2), čímž vznikl [L-3 -> SnCl][SnCl3] (7) a [L-3 -> Sn(H20)][OTf](2) (8). Studie tak odhalila, že reakce je závislá na typu ligandu. Připravené komplexy 4-8 spolu s dříve uvedeným [{2-((CH3)C=N(C6H3-2,6-iPr(2)))-6-CH3O-C5H3N}SnCl][SnCl3] (1) byly testovány jako katalyzátory pro ROP L-laktidu prostřednictvím mechanismu aktivovaného monomeru. Nakonec byla provedena výpočetní DFT studie, aby se vyhodnotily sterické a elektronické vlastnosti cínatých iontových komplexů 1 a 4-8 spolu s jejich schopností interagovat s monomerem L-laktidu.

The reactions of monomeric C,N-chelated organogermanium(II) hydride L(H)Ge⋅BH3 with organolithium salts RLi yielded lithium hydrogermanatoborates (Li(THF)2 {BH3 [L(H)GeR]})2 . Compound (Li(THF)2 {BH3 [L(H)GePh]})2 was used as a source of LiH for the reduction of organic C=O or C=N bonds in nonpolar solvents accompanied by the elimination of a neutral complex L(Ph)Ge⋅BH3 . The interaction of (Li(THF)2 {BH3 [L(H)GePh]})2 with the polar C=O bond was further investigated by computational studies revealing a plausible geometry of a pre-reactive intermediate. The experimental and theoretical studies suggest that, although the Li atom of (Li(THF)2 {BH3 [L(H)GePh]})2 coordinates the C=O bond, the GeH fragment is the active species in the reduction reaction. Finally, benzaldehyde was reduced by a mixture of L(H)Ge⋅BH3 with PhLi in nonpolar solvents.

Treatment of N,C,N-chelated organopnictogen(I) compounds ArE (1-3) (Ar=2,6-(RN=CH)2 C6 H3 , E/R=As/Dmp (1), Sb/tBu (2), and Bi/tBu (3), where Dmp=2,6-Me2 C6 H3 ) with various electron-deficient alkynes RC≡CR' (R/R'=CO2 Me (DMAD), R/R'=H/CO2 Me, or R/R'=NC5 F4 ) affords different types of heterocyclic compounds. In these reactions, 1-3 act as hidden dienes and participate in hetero-Diels-Alder (DA) reactions, a feature that has been only rarely reported for heavier pnictogen compounds. In this way, reactions of 1 furnished the set of 1-arsanaphthalenes 4-6. The most likely mechanism involves two steps, that is, an arsa-DA reaction giving a 1-arsa-1,4-dihydro-iminonaphthalene, followed by CH→NH proton migration. In contrast, this reaction sequence terminates at the first step in the case of the antimony analogue 2, thus giving the 1-stiba-1,4-dihydro-iminonaphthalenes 7 and 8. Reactions of the bismuth congener 3 gave one of two products depending on the alkyne used. Reaction of 3 with DMAD gave 1-bisma-1,4-dihydro-iminonaphthalene 9, whilst its reaction with two equivalents of HC≡C(CO2 Me) gave bismacyclohexadiene (10). All compounds have been characterized by NMR, IR, and Raman spectroscopies and X-ray diffraction analysis. The experimental data were complemented by a computational study, including a description of the reaction profiles of the hetero-DA reactions and an assessment of the aromaticities of the heterocyclic naphthalene derivatives.

Sewage treatment plants (STPs) are one of the major source of pharmaceuticals and personal care products in the aquatic environment. Generally, the effects of individual chemicals on fish are studied under laboratory conditions, which leads to results that are potentially not realistic regarding the effects of these chemicals under environmental conditions. Therefore, in this study, common carps were held in exposed pond that receive water from STP effluents for 360 days under natural conditions. Elimination of xenobiotics starts in the fish intestine, in which the microbial community strongly influences its function. Moreover, the fish intestine functions as crucial organ for absorbing lipids and fatty acids (FA), with consequent transport to the liver where their metabolism occurs. The liver is the primary organ performing xenobiotic metabolism in fish, and therefore, the presence of pollutants may interact with the metabolism of FA. The catalytic activity of CYP1A and CYP3A-like enzymes, their gene expression, FA composition and intestinal microbiome consortia were measured. The catalytic activity of enzymes and their gene and protein expression, were induced in hepatic and intestinal tissues of fish from the exposed pond. Also, fish from the exposed pond had different compositions of FA than those from the control pond: concentration of 18:1 n-9 and 18:2 n-6 were significantly elevated and the longer chain n-3 FA 20:5 n-3, 22:5 n-3 and 22:6 n-3 were significantly lowered. There were clear differences among microbiome consortia in fish intestines across control and exposed groups. Microbiome taxa measured in exposed fish were also associated with those found in STP activated sludge. This study reveals that treated STP water, which is assumed to be clean, affected measured biomarkers in common carp.

Generating monovalent pnictogens within NCN pincers has resulted in the isolation of three distinct types of 1,2-azaheteroles, highly aromatic nitrogen analogues like pyrazole-based 5, aromatic yet fluxional P- and As-derived bell-clappers 1 and 2, and hypervalent Sb and Bi derivatives 3 and 4, which are supported by 3-center, 4-electron N-E-N bonds. Careful analysis of the solid-state structures of 1-5/[5-Me][OTf] in combination with NICS calculations (at the GIAO/M06/cc-pVTZ(-PP) level) and other computational methods (NBO) suggest that simpler NC chelates may support new phosphorus- and arsenic-containing heterocycles. Indeed, reduction of ECl2 (E = P or As) derivatives supported by N-Dipp (Dipp = 2,6-diisopropylphenyl) substituted NC bidentate ligands produced 1,2-benzoazaphosphole 11 and 1,2-benzoazaarsole 12. NICS calculations revealed 11 and 12 had aromatic character on par with that of pyrazole-based 5.

N,C,N-Chelated pnictinidenes ArE [where E = As, Sb or Bi; Ar = 2,6-(tBuN[double bond, length as m-dash]CH)2C6H3] were used as ligands for the coordination of various gold(i) complexes. Thus, the reaction of ArE with [AuCl(Me2S)] gave complexes [AuCl(ArE)] [where E = As (1) or Sb (2)] that exhibited only limited stability in solution. By contrast, the reaction of ArBi with [AuCl(Me2S)] led to the immediate deposition of gold metal and the oxidation of the bismuth atom giving ArBiCl2. The treatment of a tetrameric gold alkynyl complex [Au(C[triple bond, length as m-dash]CPh)]4 with ArAs and ArSb gave ionic compounds [Au(ArAs)2]+[Au2(C[triple bond, length as m-dash]CPh)3]- [denoted as 3+[Au2(C[triple bond, length as m-dash]CPh)3]-] and [Au(ArSb)2]+[Au(C[triple bond, length as m-dash]CPh)2]- [denoted as 4+[Au(C[triple bond, length as m-dash]CPh)2]-], respectively. Finally, the reaction of ArE with the carbene gold(i) complex [Au(IPr)(MeCN)]+[BF4]- [where IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene, MeCN = acetonitrile] produced ionic complexes [Au(IPr)(ArE)]+[BF4]- [for cations: E = As (5+), Sb (6+) or Bi (7+)]. All complexes were characterized using 1H and 13C NMR, high mass accuracy electrospray ionization mass spectrometry (ESI-MS), IR and Raman spectroscopy and (except for 1) by single-crystal X-ray diffraction analysis. Furthermore, the structure and bonding of both neutral and ionic complexes with different coordination patterns have also been investigated in detail using a Density Functional Theory (DFT) computational approach.

The synthesis of the monomeric organogermanium(II) hydrides {(LGeH)M(CO)5} (M = Cr (4), W (5)) utilizing the C,N-chelated ligand L (L is [2-(CH2NEt2)-4,6-tBu2-C6H2]-) is reported. The stabilization of the GeH terminal bond in 4 and 5 is accompanied by the combination of the electronic and steric protection of the ligand L. The reactivity of the GeH terminal bond was also investigated and attempts to reduce the polar C≡N bond in tBuNC provided unexpected N-C bond cleavage reaction yielding organogermanium(II) cyanides {(LGeCN)M(CO)5} (M = Cr (6), W (7)) instead of hydrogermylation reaction

The reduction of N,C,N-chelated antimony(III) chlorides [C 6H 3-2,6-(CH=NR) 2]SbCl 2(R=Ph (1), tBu (2), Dip (3); Dip=2,6-iPr 2C 6H 3) with an appropriate amount of KC 8or Li[AlH 4] resulted in the formation of rare examples of monomeric stibinidenes [C 6H 3-2,6-(CH=NR) 2]Sb (R=Ph (4), tBu (5), Dip (6)). Similarly, the reduction of compounds 1 or 2 by two equivalents of K[B(sBu) 3H] led to the stibinidenes 4 and 5. In contrast, the analogous reaction of compound 3 resulted in the formation of an unprecedented stibinidene [C 6H 3-2-(CH=NR)-6-(CH 2NHR)]Sb (7) (R=Dip), in which the hydrogen atoms that come from the K[B(sBu) 3H] are incorporated into the ligand backbone. To gain further insight into this intriguing reactivity with K[B(sBu) 3H] and to assess the influence of the substitution at both the antimony atom and pendant substituents, we prepared compounds [C 6H 3-2-(CH=NDip)]Sb(Ph)Cl (8) and [C 6H 2-2-(CH=NDip)-4,6-(tBu) 2]SbCl 2(9). The treatment of compound 8 with K[B(sBu) 3H] smoothly led to the 1-Ph-2-Dip-1H-2,1-benzazastibole (11), whereas the reaction of compound 9 with K[B(sBu) 3H] resulted in either tBu-substituted 1-Cl-2-Dip-1H-2,1-benzazastibole (13) or the formation of unprecedented Sb−Sb dimer bis(2-Dip-1H-2,1-benzazastibole) (12) depending on the reaction stoichiometry. The miscellaneous reactivity of antimony(III) precursors with reducing agents together with the structure and bonding of the resulting products has also been investigated from a theoretical point of view.

Monomeric organogermanium(II) hydrides {(LGeH)M(CO) 5 } (M = Cr (1), W (2), L = [2-(CH 2 NEt 2 )-4,6-tBu 2 -C 6 H 2 ] – ) were treated with ortho-quinones and terminal alkyne HC≡CCO 2 Me to give {[(LH)Ge(κ 2 -O 2 -3,5-tBu 2 C 6 H 2 )]M(CO) 5 } (M = Cr (3), W (4)), {[(LH)Ge(κ 2 -O 2 -3,4,5,6-Cl 4 C 6 )]M(CO) 5 } (M = Cr (5), W (6)) and {[LGeCH=CH(COOMe)]Cr(CO) 5 } (11). These reactions proceeded as catalyst-free reductions of C=O and C≡C bonds. Experimental data demonstrated zwitterionic character of Ge(II) complexes 3–6, where the 1,3,2-benzodioxagermylenolato anion involving the GeO 2 C 2 five membered ring coordinates the M(CO) 5 fragment. This anionic part is compensated by the NHEt 2 counter cation that is part of ligand L. Reactions of 1 and 2 differ mutually in the case of reduction of HC≡CCO 2 Me. The experimental and theoretical data suggest that compound 1 reacts with HC≡CCO 2 Me to give vinyl germylene 11 as the product of the anti-Markovnikov cis-1,2-addition, while complex 2 is inactive. These results thus suggest that the reactivity of the terminal GeH bond may be tuned by its coordination to various transition metals.

Fluxes of major ions and nutrients were measured in the N-saturated mountain forest catchment-lake system of Certovo Lake (Czech Republic) from 1998 to 2014. The lake has been rapidly recovering from atmospheric acidification due to a 90% decrease in sulphate (SO42−) deposition since the late 1980s and nitrate (NO3−) contribution to the pool of strong acid anion and leaching of dissolved organic carbon (DOC) have increased. Present concentrations of base cations, phosphorus (P), total organic N (TON), and ionic (Ali) and organically bound (Alo) aluminium in tributaries are thus predominantly governed by NO3− and DOC leaching. Despite a continuing recovery lasting 25 years, the Certovo catchment is still a net source of protons (H+), producing 44 mmol m−2 yr−1 H+ on a catchment-area basis (corresponding to 35 μmol L−1 on a concentration basis). Retention of the deposited inorganic N in the catchment averages 20%, and ammonium consumption (51 mmol m−2 yr−1) and net NO3− production (28 mol m−2 yr−1) are together the dominant terrestrial H+ generating processes. In contrast, the importance of SO42− release from the soils on terrestrial H+ production is continuously decreasing, with an average of 47 mmol m−2 yr−1 during the study. The in-lake biogeochemical processes reduce the incoming acidity by ∼40%, neutralizing 23 μmol L−1 H+ (i.e., 225 mmol m−2 yr−1 on a lake-area basis). Denitrification and photochemical and microbial decomposition of DOC are the most important in-lake H+ consuming processes (50 and 39%, respectively), while hydrolysis of Ali (from tributaries and photochemically liberated from Alo) is the dominant in-lake H+ generating process. Because the trends in water chemistry and H+ balance in the catchment-lake system are increasingly related to variability in NO3− and DOC leaching, they have become sensitive to climate-related factors (drought, elevated runoff) and forest damage that significantly modify the leaching of these anions. During the study period, increased exports of NO3− (accompanied by Ali and base cations) from the Certovo catchment occurred after a dry and hot summer, after forest damage, and during elevated winter runoff. Increasing DOC export due to decreasing acid deposition was further elevated during years with higher runoff (and especially during events with lateral flow), and was accompanied by P, TON, and Alo leaching. The climate-related processes, which originally “only” confounded chemical trends in waters recovering from acidification, may soon become the dominant variables controlling water composition in N-saturated catchments.

Two gold(I) complexes of the (NHC)AuX type bearing a triazole-based N-heterocyclic carbene (NHC) ligand (1-tert-butyl-4-(4-methylphenyl)-3-phenyl-1H-1,2,4-triazol-4-ium-5-ylidene) and various halide ligands (X = Br, I) were synthesized and characterized in solution using NMR spectroscopy as well as in the solid state using X-ray diffraction techniques. The cytotoxic properties of both compounds and the precursor, (NHC)AuCl, were screened against a panel of human tumour cell lines including liver cancer (HepG2), cervical cancer (HeLa S3) and leukaemia (CCRF-CEM, HL-60) and compared to cisplatin and auranofin. It was found that the activities of the chloro and bromo derivatives were generally superior to that of cisplatin and slightly less effective compared to auranofin, except for HepG2 cells where auranofin was not as effective. In addition, the ability to induce membrane phosphatidyl serine externalization as a hallmark of apoptosis in CCRF-CEM leukaemic cells was investigated. Copyright © 2016 John Wiley & Sons, Ltd.

The concentrations of seven perfluoroalkyl substances (PFASs) were investigated in 36 European chub (Squalius cephalus) individuals from six localities in the Czech Republic. Chub muscle and liver tissue were analysed at all sampling sites. In addition, analyses of 16 target PFASs were performed in Polar Organic Chemical Integrative Samplers (POCISs) deployed in the water at the same sampling sites. We evaluated the possibility of using passive samplers as a standardized method for monitoring PFAS contamination in aquatic environments and the mutual relationships between determined concentrations. Only perfluorooctane sulphonate was above the LOQ in fish muscle samples and 52% of the analysed fish individuals exceeded the Environmental Quality Standard for water biota. Fish muscle concentration is also particularly important for risk assessment of fish consumers. The comparison of fish tissue results with published data showed the similarity of the Czech results with those found in Germany and France. However, fish liver analysis and the passive sampling approach resulted in different fish exposure scenarios. The total concentration of PFASs in fish liver tissue was strongly correlated with POCIS data, but pollutant patterns differed between these two matrices. The differences could be attributed to the metabolic activity of the living organism. In addition to providing a different view regarding the real PFAS cocktail to which the fish are exposed, POCISs fulfil the Three Rs strategy (replacement, reduction, and refinement) in animal testing.

Using relationships between the composition of precipitation and emission rates of sulphur and nitrogen compounds and dust from 1978 to 2012, we modelled concentrations of sulphate, nitrate, ammonium, chloride, and base cations and pH of precipitation in the Tatra Mountains (central Europe) back to 1900. The modelled precipitation chemistry exhibited a high degree of temporal coherence with the lake water chemistry in 1937 and during the period 1984–2014. The ionic composition of lake water reflected progress in their acidification until the late 1980s, and then a rapid recovery. The response of lake water chemistry to changes in precipitation chemistry differed for individual ions, nutrients, and among lakes, predominantly reflecting the proportions of soil in their catchments. Important differences occurred in nutrient concentrations. In-lake concentrations of dissolved organic carbon (DOC) and total organic nitrogen (TON) exhibited inverse patterns to nitrate. DOC and TON were higher in lakes with a higher proportion of soil in the catchments, and increased in many lakes during recovery from acidification, while nitrate concentrations were higher and decreased most steeply in the catchments with sparse soils. Lake water concentrations of total phosphorus (TP) were spatially similar to that of DOC and TON, but increased most steeply during recovery in lakes with a high proportion of till soils. Our results indicate that chemical recovery of mountain ecosystems is seriously modified by catchment biogeochemistry and may result not only in elevated DOC leaching, but also in an increase of terrestrial export of TON and TP to the receiving surface waters.

The bonding in heavier Group 14 zero-valent complexes of a general formula L2 E (E=Si-Pb; L=phosphine, N-heterocyclic and acyclic carbene, cyclic tetrylene and carbon monoxide) is probed by combining valence bond (VB) theory and maximum probability domain (MPD) approaches. All studied complexes are initially evaluated on the basis of the structural parameters and the shape of frontier orbitals revealing a bent structural motif and the presence of two lone pairs at the central E atom. For the VB calculations three resonance structures are suggested, representing the "ylidone", "ylidene" and "bent allene" structures, respectively. The influence of both ligands and central atoms on the bonding situation is clearly expressed in different weights of the resonance structures for the particular complexes. In general, the bonding in the studied E0 compounds, the tetrylones, is best described as a resonating combination of "ylidone" and "ylidene" structures with a minor contribution of the "bent allene" structure. Moreover, the VB calculations allow for a straightforward assessment of the π-backbonding (E→L) stabilization energy. The validity of the suggested resonance model is further confirmed by the complementary MPD calculations focusing on the E lone pair region as well as the E-L bonding region. Likewise, the MPD method reveals a strong influence of the σ-donating and π-accepting properties of the ligand. In particular, either one single domain or two symmetrical domains are found in the lone pair region of the central atom, supporting the predominance of either the "ylidene" or "ylidone" structures having one or two lone pairs at the central atom, respectively. Furthermore, the calculated average populations in the lone pair MPDs correlate very well with the natural bond orbital (NBO) populations, and can be related to the average number of electrons that is backdonated to the ligands.

A set of neutral and ionic ruthenium arene trichlorostannyl complexes are reported herein. The tin(II) compounds L 1SnCl {1; L 1 = [2-(CH 2NEt 2)-4,6-(tBu) 2C 6H 2] –} and [L 2SnCl][SnCl 3] {2; L 2 = 2,6-[(CH 3)C=N(C 6H 3-2,6-iPr 2) 2]C 5H 3N} showed a rather different reactivity towards the ruthenium complex [(η 6-cymene)RuCl] 2(η-Cl) 2. As a consequence, the neutral complex [Ru(η 6-cymene)(L 1SnCl)Cl 2] (4) and the ionic compound [L 2SnCl][Ru(η 6-cymene)(SnCl 3) 2Cl] (8) were isolated. The insertion reaction of 4 with SnCl 2 provided the neutral trimetallic ruthenium complex [Ru(η 6-cymene)(L 1SnCl)(SnCl 3)Cl] (6). Analogous ruthenium complexes [Ru(η 6-cymene)(L 3PPh 2)Cl 2] (5) and [Ru(η 6-cymene)(L 3PPh 2)(SnCl 3)Cl] (7) containing the phosphane ligand L 3PPh 2 {3; L 3 = [2,6-iPr 2-(C 6H 3)NH] –} were also prepared to evaluate the donor–acceptor strength of the tin(II)- and phosphorus-containing ligands. The structural characterization and DFT calculations of the above-mentioned complexes suggest a strong influence of the [SnCl 3] – moiety on the Ru–E interaction (E = Sn, P). The influence of the trichlorostannyl ligand on the Ru–E interaction in the complexes 4–7 was further evaluated by means of a distortion/interaction analysis.

Two silver(I) complexes of the [(NHC)2Ag]+Y− type bearing two different triazole-based N-heterocyclic carbene (NHC) ligands, [1-tert-butyl-4-(2-methoxyphenyl)-3-phenyl-1H-1,2,4-triazol-4-ium-5-ylidene and 1-tert-butyl-4-(4-methylphenyl)-3-phenyl-1H-1,2,4-triazol-4-ium-5-ylidene], were synthesized according to the modified ‘silver salt’ method. The characterization of the respective complexes in solution by NMR spectroscopy, as well as in solid state by X-ray diffraction techniques, revealed the formation of two different complexes with either an anti or a syn geometry.

Complete assignments of chemical shifts in the 1H and 13C NMR spectra for a contiguous series of [(η5-C6H7)Fe(η6-MenC6H6–n)]+ and [(η5-C5H5)Fe(η6-MenC6H6–n)]+ cations (where n = 0–6) are reported. ...

The synthesis of the amino group functionalized NHC precursor 1-tert-butyl-4-(2-((dimethylamino)methyl)-phenyl)-3-phenyl-4H-1,2,4-triazol-1-ium perchlorate has been developed. The generation and bo...

Various tri-, di- and monoorganotin(IV) catecholates were prepared independently by three different reaction pathways, e.g. elimination of a small molecule (lithium halide) from the conversion of organotin(IV) halide with lithium catecholate, condensation or protonolytic reactions of organotin(IV) oxide or hydride with catechol and reduction of a quinone by distannane, organotin(IV) hydride or stannylene. C,N-chelating 2-[(CH3)2NCH2]C6H4– = LCN, bulky amido ([2,6-(iPr)C6H3](SiMe3)N– = LN and amido-amino chelating ({2-[(CH3)2NCH2]C6H4}(SiMe3 or GePh3)N– = LNN1 or LNN2 ligands were used in this study. All tin(IV) catecholates reveal dimeric structures with six-coordinated tin atoms except for (LCN)2Sn{(3,5-(t-Bu)2C6H2]-1,2-(O)2)} which is monomeric due to the presence of two C,N-chelating ligands. All compounds, including two hydrolysis products, were characterized by a multinuclear NMR approach and X-ray diffraction techniques.

Our attempts to synthesise N→M intramolecularly coordinated diorganometallic hydrides L2MH2 [M=Si (4), Ge (5), Sn (6)] containing the CH=N imine group (in which L is C,N-chelating ligand {2-[(2,6-iPr2C6H3)N=CH]C6 H4}(-)) yielded 1,1'-bis(2,6-diisopropylphenyl)-2,2'-spriobi[benzo[c][1,2]azasilole] (7), 1,1'-bis(2,6-diisopropylphenyl)-2,2'-spriobi[benzo[c][1,2]azagermole] (8) and C,N-chelated homoleptic stannylene L2Sn (10), respectively. Compounds 7 and 8 are an outcome of a spontaneous double hydrometallation of the two CH=N imine moieties induced by N→M intramolecular coordination (M=Si, Ge) in the absence of any catalyst. In contrast, the diorganotin hydride L2SnH2 (6) is redox-unstable and the reduction of the tin centre with the elimination of H2 provided the C,N-chelated homoleptic stannylene L2Sn (10). Compounds 7 and 8 were characterised by NMR spectroscopy and X-ray diffraction analysis. Because the proposed N→M intramolecularly coordinated diorganometallic hydrides L2MH2 [M=Si (4), Ge (5), Sn (6)] revealed two different types of reduction reactions, DFT calculations were performed to gain an insight into the structures and bonding of the non-isolable diorganometallic hydrides as well as the products of their subsequent reactions. Furthermore, the thermodynamic profiles of the different reaction pathways with respect to the central metal atom were also investigated.

A set of tri- and diorganotin(IV) pseudohalides bearing the 2-(N,N-dimethylaminomethyl)phenyl-as a C,N-chelating ligand (LCN) has been prepared and structurally characterized. Triorganotin(IV) pseudohalides of the type LCNR2SnX [R = n-Bu, X = NCO (1a), NCS (1b), NCSe (1c), CN (1d); R = Ph, X = NCO (2a), NCS (2b), NCSe (2c), CN (2d)] and (LCN)2(n-Bu)SnX [X = NCO (3a), NCS (3b), NCSe (3c), CN (3d)] are monomeric both in solution and the solid state. The central tin atom in these species is five-coordinated in the solid state with distorted trigonal bipyramidal geometry. Monomeric diorganotin(IV) pseudohalides of the type (LCN)2SnX2 [X = NCO (4a), NCS (4b), NCSe (4c), CN (4d)] contain six-coordinated tin atoms with heavily distorted octahedral geometry both in solution and solid state due to the presence of two LCN units. Finally, we have found that LCN(n-Bu)Sn(NCS)2 (5) is presumably dimeric in CDCl3 and monomeric in THF-d8 or DMSO-d6 solution while it forms infinite linear polymer in the solid state via thiocyanate bridges. According to IR, multinuclear NMR spectroscopy and XRD analysis, it was found that the pseudohalide ligands of the Ndouble bondCdouble bondY type (Y = O, S, Se) are bound via nitrogen while the CN substituent act as a common cyanide ligand (i.e. binds via carbon). DFT calculations were performed for selected compounds (2a, 2b, 2d and 4d) to further support our conclusions about the nature of the Sn-pseudohalide bonds. Compound LCNSnPhI2 (6), which was prepared in the scope of this work as well has a trigonal bipyramidal structure with non-equivalent iodine atoms.

Precipitation and throughfall fluxes of major ions, nutrients (C, N, P), and metals (Al, Fe, Mn), and the chemical composition of litter fall and living plant tissue in Norway spruce stands (the Bohemian Forest; Czech Republic), were used to evaluate how microbial processes and decay of plant tissue in canopies influence canopy leaching (CL) of elements. Proton exchange for Mg2+, Ca2+, and K+ in decaying biomass and co-transport of Ca2+ and K+ out of plant cells with organic acid anions were the most likely processes contributing to CL of base cations. The CL of total P and N (and also NO3−) was minor. Important proportions of the N and P mineral forms were transformed to organic forms by microbial processes (primary and bacterial production), with the respective CL of −13.9 and 16.4 mmol m−2 yr−1 for NH4+ and organic N, and −0.33 and 0.22 mmol m−2 yr−1 for dissolved reactive P (DRP) and organic P. Most of particulate P and N in throughfall (∼90%) originated from microbial DRP and NH4+ transformations, but particulate C mostly came from the fragmentation of plant tissue (58%). Among metals, CL was not observed for Al, was small for Fe (0.3 mmol m−2 yr−1), and greatest for Mn (0.9 mmol m−2 yr−1) due to leaching from decaying tissue by acidic precipitation.

Two ethylene-bridged methylaluminium amidinates and one aluminium amidinate containing three terminal trimethylstannyl-ethynyl groups interconnected by π-coordinated potassium ions were prepared in situ. The re-oxidation of the ethylene-bridged compound by iodine followed by further reduction using the same activation procedure demonstrated the versatility of the approach. The reactivity of an ethylene-bridged methylaluminum amidinate towards HCl was examined to demonstrate the building block concept. DFT calculations were performed to gain insight into the mechanism of the in situ activation of diphenylacetylene.

Seven coinage metal(I) complexes bearing two different triazole-based N-heterocyclic carbene (NHC) ligands, [1-tert-butyl-4-{2-[(N,N-dimethylamino)methyl]phenyl}-3-phenyl-1H-1,2,4-triazol-4-ium-5-ide and 1-tert-butyl-4-(4-methylphenyl)-3-phenyl-1H-1,2,4-triazol-4-ium-5-ide], were synthesized and fully characterized in solution by NMR spectroscopy as well as in the solid state by X-ray diffraction techniques. Furthermore, the XRD analysis showed that the bidentate coordination of the amino group substituted NHC ligand, previously observed for rhodium and palladium complexes, does not take place in the solid state structure of Au(I) complexes with various halide ligands. Nevertheless, the formation of sets of two head-to-tail oriented monomers aggregated via a weak metallophilic contact was revealed for both NHC ligands as well as for all three coinage metals with different halides. These experimental data correlate quite well with the previously published theoretical study on related complexes.

The aim of this study was to compare the contamination levels of certain important fishing grounds in the Czech Republic and to assess the health risk of consuming the fish from these localities. The assessment was performed from 2006 to 2010 in 27 fishing grounds. Within this project, 707 fish from 14 different species were sampled. The concentration of selected toxic metals (Hg, Pb, Cd) and persistent organic pollutants (POPs), such as non-dioxin-like polychlorinated biphenyls (NDL-PCBs), hexachlorocyclohexane (HCH) isomers, dichlorodiphenyltrichloroethane (DDT) and its metabolites (o,p´-DDE; p,p´-DDE; o,p´-DDD; p,p´-DDD; o,p´-DDT; p,p´-DDT) and hexachlorobenzene (HCB), were analysed in the muscle tissue of the sampled fish. Atomic absorption spectrometry (AAS) was used for the analysis of toxic metals. All of the POPs were analysed using gas chromatography with an electron capture detector (GC/ECD). Common bream ( Abramis brama ) was chosen as a reference fish species for the comparison of fishing grounds. Mercury was found as a major pollutant in fish flesh at all of the sampling sites. Concentrations in excess of the maximum level (ML) of mercury in the muscle tissue of fish (0.5 mg kg −1 ) were registered in 32 samples. Concentrations of other monitored toxic metals in fish muscle were low, typically below the limit of quantification (LOQ). From the tested POPs, DDTs and NDL-PCBs were found as major pollutants. ML for NDL-PCBs (ICES-6) in muscle tissue of fish (0.125 mg kg −1 ) was exceeded in 7 samples. In case of tested pesticides, concentrations in excess of the MRL were not registered.

The complexation chemistry of the stannylene Sn{N[Si(CH3)3]2}2, first reported by Lappert in the 1970s, was investigated by 119Sn NMR chemical shift measurements. To this end, experimental NMR data...

Reaction of 2-[(dimethylamino)methyl]aniline with butyllithium, followed by conversion with triinethylsilyl, triphenylsilyl, triphenylgermyl, trimethylstannyl, or tri-n-butyl-stannyl chloride, gives the corresponding substituted aniline. These compounds were further deprotonated by butyllithium and reacted with germanium, tin, and lead dichlorides, respectively, in both stoichiometric ratios 2:1 and 1:1, providing the target homo- ([2-(Me(2)NCH(2))C(6)H(4)(YR(3))N](2)M) and heteroleptic ([2-(Me(2)NCH(2))C(6)H(4)(YR(3))N]MCl) germylenes and stannylenes, where M = Ge, Sn, Y = Si, Ge, and R = Me, Ph. Unlike all of these cases, the heteroleptic plumbylene can only be obtained with this reaction when the amide is substituted by a trimethylsilyl moiety. Anilines substituted by trimethyltin or tri-n-butyltin moieties gave transmetalation products after the second deprotonation by butyllithium. The trimethyltin-substituted stannylenes could likewise not be obtained by hexamethyldisilazane elimination of (trimethylstannyl)-2-[(dimethylamino)methyl]aniline with 0.5 mol equiv of either bis[bis(trimethylsilyl)amido]tin or bis[bis(trimethylsilyl)amido]tin chloride}. Products of these reactions are heterocubanes with compositions {[2-(Me(2)NCH(2))C(6)H(4)N]Sn}(4) and [2-(Me(2)NCH(2))C(6)H(4)N](2)-(mu(2)-SnMe(2))(2), respectively, and Me(4)Sn or Me(3)SnCl. The structures of trimethylsilyl- and triphenylgermyl-substituted germylenes, stannylenes, and plumbylenes, as well as a number of their precursors, in the crystalline state, were investigated by X-ray diffraction and NMR spectroscopy in solution. Density functional theory methods were used for evaluation of the structures of several compounds.

The ladder-like structure of the tetranuclear title compound, [Sn(4)(C(6)H(5))(4)Cl(2)O(2)(OH)(2)(C(9)H(13)N)(2)(C(9)H(12)N)(2)]Cl(2)·10CDCl(3), consists of two five- and two six-coordinated Sn(IV) atoms bridged by oxide or hydroxide groups. The chelating ligands reveal rather strong Sn-N bonds [2.517 (4) Å], but the protonated dimethylamino groups in the periphery of the complex show no interaction with the metal atoms. The complex cation is located on an inversion centre. The chloride anion is linked to the complex mol-ecule by strong intra-molecular O-H⋯Cl and N-H⋯Cl hydrogen bonds. Five independent deuterochloroform accompany the complex, two of them are disordered [occupancy ratios 0.63 (2):0.27 (2) and 0.60 (2):0.40 (2)].

Sewage water treatment plants (STPs) are frequently associated with the release of xenobiotics and, consequently, with biological responses of fish to these substances. The impact of three STPs situated on small streams was assessed in 2009. Brown trout (Salmo trutta fario L.), captured upstream and downstream of these STPs, were used as biomonitors. The concentrations of 39 organic pollutants (PCBs, OCPs, PBDEs, HBCDs, and MCs), and the biological responses related to oxidative stress (lipid peroxidation and carbonyl protein), and antioxidant responses (superoxide dismutase, glutathione peroxidase and glutathione reductase) were measured. Through chemometrics of these parameters, three groups with 97.62% of the total accumulated variance were distinguished. Integration of the assessed biomarkers using the IBR index, ranked environment impact on sites as: DS Pacov > DS Prachatice > DS Brloh > US Pacov > US Prachatice > US Brloh (most to least affected). STPs are a major source of xenobiotic pollution in streams of the Czech Republic. The combined use of chemical analysis and biological responses is necessary to validate the efficacy of a battery of biomarkers chosen to detect environmental stress due to pollution.

We reconstructed the history of terrestrial export of aluminium (Al) to Plesné Lake (Czech Republic) since the lake origin approximately 12,600 year BC, and predicted Al export for 2010-2050 on the basis of previously published and new data on mass budget studies, palaeolimnological data, and MAGIC modelling. We focused on three major Al forms; ionic Al (Al(i)), organically-bound Al (Al(o)), and particulate Al hydroxide [Al(OH)(3)]. In early post-glacial time, Plesné Lake received high terrestrial export of Al, but with a minor proportion of Al(OH)(3) (4-25 microM), and concentrations of Al(i) and Al(o) were negligible. Since the forest and soil development ( approximately 9900-9000 year BC), erosion has declined and soil organic acids increased export of Al(o) from soils. The terrestrial Al(o) leaching ( approximately 7.5 microM) persisted throughout the Holocene until the industrial period. Then, Al(i) concentrations continuously increased (up to 28 microM in the mid-1980s) due to atmospheric acidification; the Al(i) leaching was mostly associated with sulphate. The proportion of Al(i) associated with nitrate has been increasing since the beginning of lake recovery from acidification after approximately 1990 due to reduction in sulphur deposition and nitrogen-saturation of the catchment, leading to persistent nitrate leaching. Currently, nitrate has become the dominant strong acid anion and the major Al(i) carrier. Al(o) (5.5 microM) is predicted to dominate Al concentrations around 2050, but the predicted Al(i) concentrations ( approximately 4 microM) are uncertain because of uncertainty associated with the future nitrate leaching and its effect on soils.

Six palladium(II) complexes bearing three different triazole-based N-heterocyclic carbene (NHC) ligands, [1-tert-butyl-4-{2-[(N,N-dimethylamino)methyl]phenyl}-3-phenyl-1H-1,2,4-triazol-4-ium-5-ide, 1-tert-butyl-4-(2-methoxyphenyl)-3-phenyl-1H-1,2,4-triazol-4-ium-5-ide, and 1-tert-butyl-4-(4-methylphenyl)-3-phenyl-1H-1,2,4-triazol-4-ium-5-ide], were synthesized and fully characterized. NMR spectroscopy and X-ray diffraction analysis revealed that the amino-group-substituted NHC ligand is coordinated in bidentate fashion, forming a monocarbene chelate complex with an additional intramolecular Pd ← N bond with the nitrogen donor atom. The 4-methylphenyl- and 2-methoxyphenyl-substituted NHC ligands coordinate as C-monodentate donors, forming simple biscarbene Pd(II) complexes. The evaluation of the catalytic performance in the Suzuki–Miyaura cross-coupling reaction revealed very promising performance of the intramolecularly coordinated monocarbene complexes under relatively mild conditions even in direct comp...

The aim of this study was to compare the effect of four anaesthetics on the haematological and blood biochemical profiles of vimba bream ( Vimba vimba). The haematological and blood biochemical profiles of vimba bream were evaluated 10 min and 24 h after anaesthesia with MS 222 (100 mg/l), clove oil (33 mg/l), 2-phe - noxyethanol (0.4 ml/l), Propiscin (1.0 ml/l) and compared to non-anaesthetised controls. The 10 min exposure to any of the anaesthetics did not show any effects on haematological profiles. The exposure to 2-phenoxyethanol and Propiscin significantly ( P < 0.01) influenced levels of glucose and ammonia, and the activity of aspartate ami - notransferase compared with the control group. The level of triacylglycerols was significantly ( P < 0.01) increased and the activity of lactate dehydrogenase was significantly ( P < 0.01) decreased by exposure to MS 222. The use of clove oil showed no effects on the haematological and blood biochemical profiles and is recommended as a suit

Homobimetallic metallophilic interactions between copper, silver, and gold-based [(NHC)MX]-type complexes (NHC=N-heterocyclic carbene, i.e, 1,3,4-trimethyl-4,5-dihydro-1H-1,2,4-triazol-5-ylidene; X=F, Cl, Br, I) were investigated by means of ab initio interaction energies, Ziegler-Rauk-type energy-decomposition analysis, the natural orbital for chemical valence (NOCV) framework, and the noncovalent interaction (NCI) index. It was found that the dimers of these complexes predominantly adopt a head-to-tail arrangement with typical M⋅⋅⋅M distance of 3.04-3.64 Å, in good agreement with the experimental X-ray structure determined for [{(NHC)AuCl}2 ], which has an Au⋅⋅⋅Au distance of 3.33 Å. The interaction energies between silver- and gold-based monomers are calculated to be about -25 kcal mol(-1) , whereas that for the Cu congener is significantly lower (-19.7 kcal mol(-1) ). With the inclusion of thermal and solvent contributions, both of which are destabilizing, by about 15 and 8 kcal mol(-1) , respectively, an equilibrium process is predicted for the formation of dimer complexes. Energy-decomposition analysis revealed a dominant electrostatic contribution to the interaction energy, besides significantly stabilizing dispersion and orbital interactions. This electrostatic contribution is rationalized by NHC(δ(+) )⋅⋅⋅halogen(δ(-) ) interactions between monomers, as demonstrated by electrostatic potentials and derived charges. The dominant NOCV orbital indicates weakening of the π backdonation in the monomers on dimer formation, whereas the second most dominant NOCV represents an electron-density deformation according to the formation of a very weak M⋅⋅⋅M bond. One of the characteristic signals found in the reduced density gradient versus electron density diagram corresponds to the noncovalent interactions between the metal centers of the monomers in the NCI plots, which is the manifestation of metallophilic interaction.