Theoretical studies on all-metal binuclear sandwich-like complexes M2(η4-E4)2 (M=Al, Ga, In; E=Sb, Bi)

A series of all-metal binuclear sandwich-like complexes with the formula M(2)(η(4)-E(4))(2) (M=Al, Ga, In; E=Sb, Bi) was studied by density functional theory (DFT). The most stable conformer for each of the M(2)(η(4)-E(4))(2) species is the staggered one with D (4d) symmetry. The centred metal-metal bond in each M(2)(η(4)-E(4))(2) species is a covalent single bond, with the main contributors to these covalent bonds being the a(1) and e orbitals. For all these species, the interactions between the centred metal atoms and the all-metal ligands are covalent; η(4)-Sb (4) (2-) has a stronger ability to stabilize metal-metal bonds than η(4)-Bi (4) (2-). Nucleus-independent chemical shifts (NICS) values and molecular orbital (MO) analysis reveal that the all-metal η(4)-Sb (4) (2-) and η(4)-Bi (4) (2-) ligands in M(2)(η(4)-E(4))(2) possess conflicting aromaticity (σ antiaromaticity and π aromaticity), which differs from the all-metal multiple aromatic unit Al (4) (2-). In addition, all of these M(2)(η(4)-E(4))(2) species are stable according to the dissociation energies of M(2)(η(4)-E(4))(2)?→?2 M(η(4)-E(4)) and M(2)(η(4)-E(4))(2)?→?2 M?+?2E(4), and these stable species can be synthesized by two-step substitution reactions: CpZnZnCp?+?2E (4) (2-) →?[E(4)ZnZnE(4)](2-)?+?2Cp(-) and [E(4)ZnZnE(4)](2-)?+?2 M (2) (+) →?E(4)MME(4)?+?2Zn(+).     

Fast atom bombardment,electron impact and chemical ionization mass spectrometry of the neutral 18-electron species M(CO)2(CNR)2(PR′3)2 (MMo or W)

The molybdenum(0) and tungsten(O) complexes of the type M(CO)₂(CNR)₂(PR′₃)₂ have been studied using a variety of mass spectral techniques, viz. fast atom bombardment (FAB), electron impact (EI), and both positive- and negative-ion chemical ionization (PICI and NICI) mass spectrometry. The FABMS technique gave the most structurally informative spectra with the observation of the molecular ions M⁺ (100% relative abundance in the case of MW) and in some instances the pseudomolecular ion (M + H)⁺. Fragmentation ions arising from competitive ligand loss (CO versus RNC versus PR′₃) were observed, as well as those formed by loss of H from fragment ions and dealkylation of RNC ligands. The EI and PICI spectra were not especially useful due to the relatively low thermal stability of these complexes, while the NICI spectra gave an abundance of ions that resulted from ligand redistribution reactions. Of special note were anions that contained M(CO)₄ and M(CO)₃ fragments. Dealkylation of the RNC ligands to give cyanometallate anions was also prevalent.     

Life history of Lineus viridis (Müller, 1774) (Heteronemertea, Nemertea)

Lineus viridis is a common nemertean species of North-Atlantic intertidal sand flats. Its mating behaviour is peculiar insofar as this species is reported to be polyandric. However, detailed information on this topic is lacking. In order to get more data on the reproduction, oogenesis and life history of this species, a population in the Wadden Sea on the Isle of Sylt (North Sea) was studied between 2005 and 2011. We conducted regular surveys, during which we sampled, measured and recorded the sex status of 25–100 individuals at each sampling event; at least three individuals were fixed for histological studies at each sampling date. In addition, animals were kept in the laboratory for 3?years to complement field data on sexual identity. Lineus viridis was found to reproduce annually in several successive year; the females are significantly larger than the males. Oogenesis starts in spring, shortly after the preceding reproductive period, and continues until the end of December. Spermiogenesis starts in late autumn and also ends late in December. During mating, several males are generally found crawling on a single female, which forms a cocoon that encloses both the female and the associated males. Fertilization is internal. While females discharge all of their eggs during a single mating event and lose more than 40% of their wet weight, males only empty a few of their gonads, and are thus able to fertilize more than one female. Our study clearly shows that Lineus viridis is a perennial, iteroparous species with a pronounced sexual size dimorphism. During this long-term study, no evidence for sequential hermaphroditism has been found. The observed polyandric mating system in this species raises further questions regarding mate and sperm competition that deserve additional research.     

125Te Mössbauer spectra of the intercalation compound (Te2)2(I2)

The quadrupole split asymmetric ¹²⁵Te Mössbauer spectrum recorded from the compound (Te₂)₂(I₂), in which monomolecular planar layers of iodine molecules are intercalated between layers of tellurium, is a reflection of the distorted environment of tellurium atoms in a two-dimensional layered compound in which the elongated flat crystals are preferentially orientated. The differences between the Mössbauer parameters recorded from (Te₂)₂(I₂) and those recorded from elemental tellurium and the tellurium(0) species in the compound Te₃Cl₂ are associated with small differences between the environments of tellurium in the three compounds. The Mössbauer spectra recorded from (Te₂)₂(I₂) are consistent with a recently proposed model on which the electronic band structure of (Te₂)₂(I₂) has been derived.     

Synthesis, characterization, and antibacterial and anticancer screening of {M2+–Co3+–M2+} and {Co3+–M2+} (M?is?Zn, Cd, Hg) heterometallic complexes

The cobalt(III) complexes Et₄N[Co(L¹)₂] and [Co(L²)₃] [H₂L¹ is 2,6-bis(N-(2-pyridyl)carbamoyl)pyridine and HL² is 2-(N-(2-pyridyl)carbamoyl)pyridine] were used as the building blocks for preparing a series of {M²⁺?CCo³⁺?CM²⁺} (where M?is?Zn, Cd, or Hg) and {Co³⁺?CM²⁺} (where M?is?Zn or Cd) heterometallic complexes. All heterometallic complexes were characterized using a host of spectroscopic methods (IR, NMR, and UV/vis spectroscopy and mass spectrometry), elemental analysis, and conductivity measurements. One of the representative compounds, {Hg²⁺?CCo³⁺?CHg²⁺}, was characterized crystallographically, and it was revealed that two Hg(II) ions are coordinated within the clefts created by the building block Et₄N[Co(L¹)₂]. The results of screening for anticancer activity against the human brain tumor U87 cell line and antibacterial activity against a range of resistant (Pseudomonas aeruginosa and Proteus vulgaris) as well as standard (Staphylococcus aureus SA 96, P. aeruginosa MTCC 1688, Klebsiella planticola MTCC 2272, and Escherichia coli T7) bacterial strains indicate promising activities. Notably, the observed activity was found to vary with the type of building block and the secondary metal ion present in the heterometallic complex. Treatment-induced cell death [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, MTT and macrocolony assay), growth inhibition, cytogenetic damage, cell cycle delay, and apoptosis were studied as the parameters for cellular response.     

Syntheses and michael additions to vinylidene diphosphine complexes of type [M(CO)4{(Ph2P)2CCH2}] (MCr,Mo or W)

Treatment of [M(CO)₄Ph₂PCHPPh₂]⁻ with CH₃- OCH₂Cl at 20 °C gave the methoxymethyl derivations [M(CO)₄{Ph₂PCH(CH₂OCH₃)PPh₂}] (MCr or W), but a similar treatment at 80 °C gave derivatives of a vinylidene diphosphine [M(CO)₄(Ph₂P)₂C CH₂]. Treatment of [M(CO)₄Ph₂PCHPPh₂]⁻with CH₃CHClOCH₃ at 20 or 80 °C gave only [M(CO)₄- (Ph₂P)₂CHCH(CH₃)OCH₃] (MCr or W). The vinylidene diphosphine complexes [M(CO)₄(Ph₂P)2- CCH₂] (MCr, Mo or W) were even more easily prepared by treating [M(CO)₆] with (Ph₂P)₂CCH₂ (vdpp) in hot solvents such as CH₃OCH₂CH₂OCH₂- CH₂OCH₃.Treatment of [W(CO)₄vdpp] with LiBuⁿ followed by methanol gave [W(CO)₄(Ph₂P)₂CHCH₂Buⁿ] (1c), i.e. conjugate addition to the CCH₂ occurs. 1c was also made by treating [W(CO)₄(Ph₂P)₂CH]⁻ with n-pentyl-iodide. Similarly LiMe was added to [W(CO)₄(Ph₂P)₂CCH₂]. Treatment of [M(CO)₄- vdpp] with NaCH(COOEt)₂ gave [M(CO)₄(Ph₂- P)₂CHCH₂CH(COOEt)₂] (MW or Mo). Pyrrolidine added to the CCH₂ bonds of [M(CO)₄vddp] to give [M(CO)₄(Ph₂P)₂CHCH₂NC₄H₈]. ³¹p and ¹H NMR and IR data are given.     

The population biology ofPlanaria torva (Müller) (Turbellaria,Tricladida)

Summary 1. A quantitative study of the population biology ofPlanaria torva (Müller) living in a productive lake, based on monthly samples over a period of 20 months, is presented. 2. Samples of triclads, their cocoons and other organisms were taken from bricks placed at a shallow depth in the lake. They provided relative information on changes in population size structure and demonstrated the temporal breeding of this triclad. 3. Cocoon production byP. torva began in January and reached a peak in March–April. This was followed by a peak in recently-hatched young during May–June. Adults reached a maximal proportion of the total population in January and most had died by July. 4. Changes in size structure suggest that intra-specific competition occurred during June–July following the recruitment of young. This hypothesis is supported by other independent evidence. 5. Attempts to measure fecundity based on cocoons and young gave very different results attributed to the sampling technique.     

3,3′-Bipyridazine: the ‘second-best’ bidiazine ligand for M(CO)4 fragments (M = Cr,Mo, W)

Owing to its relatively high basicity (pK_a1 = 3.37), the title ligand yields M(CO)₄ chelate complexes (M = Cr, Mo, W) which have both metal-to-ligand charge transfer absorption maxima at longer wavelengths than corresponding 2,2′-bipyrimidine and 2,2′-bipyrazine compounds. After 4,4′-bipyrimidine, 3,3′-bipyridazine is the second-best π acceptor among the symmetrical bidiazines with α-diimine structure.     

中国蚊类新纪录,1.Heizmannia(M.)achaetae(Leicester,1908)

领蚊Heizmannia是亚热带丛林和竹林中的吸血蚊类之一,但我国过去除台湾省外对它们所知不多。近年来我们在广东(海南岛)、广西、江西、福建、云南等山区采到了8种领蚊,包括3种我国新纪录,本文报告的H.(M.)achaetae(Leicester,1908)(无鬃领蚊)即为其中之一。     

ESEEM and Mössbauer studies of the ferriheme model compound bis(3-aminopyrazole)tetraphenylporphyrinatoiron(III) chloride, [TPPFe(NH2PzH)2]Cl

A model heme complex, bis(3-aminopyrazole)tetraphenylporphinatoiron(III) chloride, [TPPFe (NH₂PzH)₂]Cl, for which the EPR g-values lead to a rhombicity V/Δ=1.2 if g _zz is the largest g-value, have been investigated by electron spin echo envelope modulation (ESEEM) and Mössbauer spectroscopies. The ESEEM studies focus on the proton sum frequency peaks at near twice the proton Larmor frequency. Analysis of the distant proton peak (mainly due to the pyrrole-H) at exactly twice the proton Larmor frequency shows conclusively that g _zz is aligned along the normal to the porphyrin plane, and thus the electron configuration is (d _xy )²(d _xz ,d _yz )³, with g _zz >g _yy >g _xx . This system is thus another violation to Taylor's "proper axis system" rule. The near proton (the α-H and N-H of the axial ligands) peaks provide distance information for those protons from the metal. Magnetic Mössbauer studies of the same complex confirm the (d _xy )²(d _xz ,d _yz )³ ground state and indicate that, as is the case for cytochrome P450_cam, A _xx is the largest magnitude A-value, and is negative in sign. Other low-spin iron(III) porphyrinates also have A _xx of negative sign, but usually the magnitude is only about half that of A _zz , which is always positive in sign.     

Lymnaea truncatula (Müller, 1774)--the 1st and 2d intermediate hosts of Echinostoma revolutum (Fr?hlich, 1802) and Hypoderaeum conoideum (Bloch, 1782)

Lymnaea truncatula (Müller, 1774) is recorded as the first and second intermediate host of Echinostoma revolutum (Fr?hlich, 1802) and Hypoderaeum conoideum (Bloch, 1782) Adults were obtained by the feeding of metacercariae to chickens.     

Immunohistochemical analysis of adhesive papillae of Clavelina lepadiformis (Müller, 1776) and Clavelina phlegraea (Salfi, 1929) (Tunicata,Ascidiacea)

Almost all ascidian larvae bear three mucus secreting and sensory organs, the adhesive papillae, at the anterior end of the trunk, which play an important role during the settlement phase. The morphology and the cellular composition of these organs varies greatly in the different species. The larvae of the Clavelina genus bear simple bulbous papillae, which are considered to have only a secretory function. We analysed the adhesive papillae of two species belonging to this genus, C. lepadiformis and C. phlegraea, by histological sections and by immunolocalisation of β-tubulin and serotonin, in order to better clarify the cellular composition of these organs. We demonstrated that they contain at least two types of neurons: central neurons, bearing microvilli, and peripheral ciliated neurons. Peripheral neurons of C. lepadiformis contain serotonin. We suggest that these two neurons play different roles during settlement: the central ones may be chemo- or mechanoreceptors that sense the substratum, and the peripheral ones may be involved in the mechanism that triggers metamorphosis.Key words: Settlement, neurotransmitter, serotonin, β-tubulin, papillary nerves, metamorphosis.Ascidians (phylum Chordata; subphylum Tunicata) are sessile filter-feeding organisms that can be found in all benthic marine environments and develop through a swimming tadpole larva. Larvae of colonial ascidians have a short planktonic life that can vary from minutes to hours (Burighel and Cloney, 1997). Prior to metamorphosis, the larva attaches to the substratum by means of peculiar organs of ectodermic origin, located in the anterior region of the trunk. These organs, known as adhesive papillae, secrete sticky substances and effect primary adhesion of the larva to the substrate (Cloney, 1977). They have an important role in the initiation of settlement and metamorphosis and there is evidence that, at least in some species, they participate in substrate selection (Torrence and Cloney, 1983; Svane and Young, 1989; Groppelli et al., 2003). In many species, they are organised in a triangular field, whereas in others they are aligned along the mid-sagittal plane of the trunk. Adhesive papillae have been classified into two types: eversible papillae, typical of some colonial species, composed by several cell types and rapidly changing shape as they touch the substrate, and non-eversible papillae, typical of solitary species, which do not change shape after settlement (Burighel and Cloney, 1997).With few exceptions, all adhesive papillae are formed by elongated secretory and sensory cells, which are recognised as primary neurons (Cloney, 1977, 1979). It has been proposed that sensory cells may detect the chemical and physical characteristics of the substratum at potential sites for settlement and metamorphosis (Young and Braithwaite, 1980; Groppelli et al., 2003).The presence of primary neurons in the papillae has been reported in the larvae of several species such as Distaplia occidentalis, Diplosoma macdonaldi, Phallusia mammillata, Ciona intestinalis and Ascidia malaca (Cloney, 1977;Torrence and Cloney, 1983; Sotgia et al., 1998; Takamura, 1998; Gianguzza et al., 1999).These neurons have axons that join together to form the papillary nerves that enter the central nervous system at the level of the sensory vesicle (Imai and Meinertzhagen, 2007).Recently, different neurotransmitters have been localised in the sensory neurons of the papillae of different species. The presence of GABAergic neurons has been reported in the papillae of Ciona savygni (Brown et al., 2005) and of Ciona intestinalis (Zega et al., 2008), while serotonergic neurons have been localised in the papillae of Phallusia mammillata (Pennati et al., 2001) and Botrylloides leachi (Pennati et al., 2007). Moreover, it has been demonstrated that serotonin plays a role in the mechanism triggering metamorphosis in ascidians (Zega et al., 2005).After attachment, all papillae retract to draw the larva closer to the substratum. In the colonial ascidian Distaplia occidentalis, the process of retraction is reversibly inhibited by cytochalasin B, suggesting that microfilaments are involved in this process (Cloney, 1979).Clavelina lepadiformis is a colonial species, whose larvae bear non-eversible simple bulbous papillae.They have been described as being formed only by columnar glandular cells, whose secreted material is responsible for the sticky properties of the organ. These papillae do not contain sensory cells and were considered the simplest among those studied (Turon, 1991).In this work, the morphology of the adhesive papillae of C. lepadiformis and C. phlegraea was further investigated by histological analysis and immunolabelling techniques in order to clarify the actual cellular composition and function of these organs.     

A chromosome study ofSchistocephalus solidus (Müller, 1776) (Cestoda: Pseudophyllidea)

Analysis of Giemsa-stained metaphase plates of plerocercoids ofSchistocephalus solidus revealed the mode diploid number of chromosomes for this species as 2n=18. Chromosome pairs 1, 5, 6, 8 and 9 are metacentric, pairs 2, 4 and 7 are subtelocentric, and pair 3 is subtelocentric to acrocentric. The karyotype is characterised by mean absolute chromosome length between 1.9 and 5.9 m and a total chromosome length of the haploid complement of 32 m. A comparison with other known karyotypes of related species of pseudophyllidean cestodes was made.     

MCl2 (M=Hg,Cd, Zn,Mn) catalysed hydrochlorination of acetylene – a Density Functional Theory study

A Density Functional Theory method has been employed in this research to conduct an in-depth study of the correlation between the conversion of acetylene to vinyl chloride catalysed by MCl₂ (M=Hg, Cd, Zn, Mn) and the electron affinity. From the analysis of the adsorption energy and energy profile of acetylene hydrochlorination reaction, combined with Fukui indices and outer-shell Mulliken population change alongside reaction pathway, it can be concluded that, the outermost electron migration is the main factor affecting the catalytic property of MCl₂ (M=Hg, Cd, Zn, Mn) catalyst. The Mulliken population change of the central atom M²⁺ (M=Hg, Cd, Zn) share similar tendency along the reaction pathway, the only difference is Hg²⁺ gained more electrons than the other two when acetylene got absorbed, and that proved that Hg(II) got better electron withdrawing, which is a main motivator of better catalytic properties in acetylene hydrochlorination reaction.     

Muridae,Zapodidae und Eomyidae (Rodentia,Mammalia) des Eichkogels bei MÖdling (NiederÖsterreich)

Four rodent species,Parapodemus lugdunensis Schaub 1938, ?Progonomys woelferi Bachmayer &Wilson 1970,Protozapus intermedius Bachmayer &Wilson 1970 andKeramidomys aff.mohleri Engesser 1972 from the freshwater marl of Eichkogel are described. The presence ofParapodemus lugdunensis associated with other rodents give us the possibility to correlate Eichkogel and Kohfidisch in Austria with Turolian mammal-faunas of Germany, France and Spain.     

A novel vanadium(V) homocitrate complex: synthesis,structure, and biological relevance of [K2(H2O)5][(VO2)2(R,S-homocitrate)2]·H2O

Initial investigations into the possible roles of homocitric acid in the biosynthesis and function of the active site cofactor of nitrogenase resulted in the isolation and characterization of the dinuclear vanadium(V) species [K₂(H₂O)₅][(VO₂)₂(R,S-C₇H₈O₇)₂]·H₂O ( 1). Complex 1 represents the first synthetic structurally characterized transition metal homocitrate complex and may represent an early mobilized precursor in the biosynthesis of VFeco. Compound 1 was characterized by a variety of physical methods, including X-ray crystallography. Crystal data: space group P?* (#2), with a?=?10.292 (3)?Å, b?=?16.663 (3)?Å, c?=?8.343 (1)?Å, α?=?95.93 (1)°, β?=?105.74 (2)°, γ?=?90.86 (2)°, V?=?1386 (1)?ų, and Z?=?2. The homocitrate ligand is coordinated to the vanadium(V) atoms in a bidentate fashion via the deprotonated bridging hydroxyl group and a carboxylate donor. This unique coordination mode accurately mimics the coordination of homocitrate to the cofactor of nitrogenase.     

Synthesis,X-ray structures,and magnetic properties of heterometal dinuclear Cr(III)–M(II) complexes

New 3,5-bis(2-pyridyl)pyrazolato (bpypz) bridged heterometal dinuclear complexes [(nta)Cr(μ-bpypz)M^II(picen)]⁺ (M = Mn(II), Ni(II)) and [(acac)₂Cr(μ-bpypz)Ni^II(picen)]²⁺ (nta = nitrilotriacetate, picen = N,N′-bis(2-pyridylmethyl)ethylenediamine, acac = acetylacetate) were synthesized and characterized by the X-ray analysis, ESI-MS and the magnetic measurements, and/or ²H NMR spectra. The molecular structures were compared from a viewpoint of the conformation of the picen depending on M^II ionic radii or different modes of hydrogen bonds. The picen in [(nta)Cr(μ-bpypz)Mn^II(picen)]BF₄ takes an abnormal conformation with intramolecular bifurcated three-center hydrogen bonds between two carboxylate oxygens of nta and an amine proton of the picen as found for the previously reported corresponding Fe(II) complex [K. Ni-iya, A. Fuyuhiro, T. Yagi, S. Nasu, K. Kuzushita, S. Morimoto, S. Kaizaki, Bull. Chem. Soc. Jpn. 74 (2001) 1891]. On the other hand, for both Ni(II)-nta and Ni(II)-acac complexes, the picen takes a normal conformation with only a two-center hydrogen bond between non-bridging ligands. The magneto-structural relation is discussed for the Cr(III)–Ni(II) complexes in connection with the orthogonality or orbital overlap arising from the difference in distortion around Cr(III) moiety.     

A grid-based, satellite-image supported, multi-attributed vegetation mapping method (MÉTA)

In this paper we present the main characteristics of a new, grid-based, landscape-ecology-oriented, satellite-image supported, field vegetation mapping method, called MÉTA (MÉTA stands for Magyarországi Él?helyek Térképi Adatbázisa: GIS Database of the Hungarian Habitats). The goals of the MÉTA method based vegetation mapping program (MÉTA mapping) include the following: (1) to map the actual (semi-)natural vegetation of Hungary; (2) to evaluate Hungarian (semi-)natural vegetation heritage for conservation purposes; (3) to evaluate the present state of Hungarian landscapes from a vegetation point of view; (4) to collect vegetation and landscape ecological data for the prognosis of future changes of vegetation and the landscape. Spatial resolution, mapped attributes and mapping methods were developed to meet these goals. The MÉTA method uses a hexagon grid with cells of 35 hectares. In the hexagons, habitat types are listed, then the area, naturalness-based habitat quality, spatial pattern in the hexagon, effect of the neighbourhood, connectedness, and threats are recorded for each habitat type. Other attributes are recorded in the hexagons: potential natural vegetation, area occupied by invasive plant species, area of old fields, land use of grasslands, and landscape health status (naturalness and regeneration potential of the landscape in general). One hundred hexagons form a quadrat — mainly for practical, organizational reasons, but also for collecting certain vegetation data at this spatial scale. For standardization of mapping, three different pre-printed data sheets and two different kinds of guides have been composed (Mapping Guide and Habitat Guide) and field trainings were organized. For standardization of estimation of naturalness-based habitat quality and regeneration potential field examples were prepared for each habitat type and each category of these attributes.