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In parasite–host interactions host species may differ in their ability to fight parasitic infections, while other ecological interactions, including competition, may differentially alter their physiological state, making them even more susceptible to parasites. In this study, we analyse the haemogregarine blood parasites infecting two competing lizard species, Iberolacerta horvathi and Podarcis muralis, and explore host–parasite relationships under different host competition scenarios. Both species were infected with haemogregarine parasites belonging to the genus Karyolysus. Using the 18S rRNA gene, six new Karyolysus haplotypes were identified clustering with other Central and Eastern European samples, and widely shared between both lizard hosts. Haemogregarine infections were detected at all sampled sites with over 50% of individuals parasitized. Overall, I. horvathi was more frequently and also more intensely parasitized than P. muralis, with higher infection rates observed in syntopy. Males of both species tended to be more frequently infected and showed a higher infection intensity than conspecific females. The results suggest that parasitisation by haemogregarines may be relevant in the dynamics of the competitive relationship between these lizard species. More studies, including immunological response analysis, and the identification of the vectors are needed to better understand host–parasite relationships and competition. [ABSTRACT FROM AUTHOR]

Obligate parthenogenesis is found in only 0.1% of the vertebrate species, is thought to be relatively short lived and is typically of hybrid origin. However, neither the evolutionary persistence of asexuality in vertebrates, nor the conditions that allow the generation of new parthenogenetic lineages are currently well understood. It has been proposed that vertebrate parthenogenetic lineages arise from hybridisation between two divergent taxa within a specific range of phylogenetic distances (the ‘Balance Hypothesis’). Moreover, parthenogenetic species often maintain a certain level of hybridisation with their closest sexual relatives, potentially generating new polyploid hybrid lineages. Here we address the role of hybridisation in the origin and evolutionary lifespan of vertebrate parthenogens. We use a set of microsatellite markers to characterise the origins of parthenogens in the lizard genus Darevskia, to study the distinctiveness of sexual and asexual taxa currently in sympatry, and to analyse the evolutionary consequences of interspecific hybridisation between asexual females and sexual males. We find that parthenogens result from multiple past hybridisation events between species from specific lineages over a range of phylogenetic distances. This suggests that the Balance Hypothesis needs to allow for lineage-specific effects, as envisaged in the Phylogenetic Constraint Hypothesis. Our results show recurrent backcrossing between sexual and parthenogenic Darevskiabut neither gene flow nor formation of new asexual lineages. We suggest that, along with their demographic advantage, parthenogens gain additional leverage to outcompete sexuals in nature when the retention of sexual reproductive machinery allows backcrossing with their sexual ancestors.

Describir los patrones de consumo de alcohol y de episodios de consumo intensivo (ECI) en una muestra de estudiantes de Ciencias de la Salud, así como identificar factores asociados.

To describe the alcohol drinking patterns and binge drinking episodes (BDE) in a sample of Health Science students, as well as identify associated factors.

Oceanic islands are hotspots of biodiversity due to their high levels of endemism, with the Canary Islands being a notable example. A previous molecular study on the biogeography and host associations of haemogregarines (Apicomplexa: Adeleorina) infecting lizards from this archipelago detected seven parasite haplogroups. These haplogroups exhibited high host-specificity and geographical structure, suggesting that they might correspond to distinct biological identities. In this study, along with sequencing a longer fragment of the 18S rRNA, we further explore the distinctiveness of these parasites by analysing their morphology, effects on host erythrocytes and parasitaemia levels. These lines of evidence together with their genetics, host associations, frequency of occurrence and geographical distribution support them as different biological entities. As such, we describe seven new species: Karyolysus canariensis sp. nov., Karyolysus galloti sp. nov., Karyolysus stehlini sp. nov., Karyolysus gomerensis sp. nov., Karyolysus atlanticus sp. nov., Karyolysus tinerfensis sp. nov. and Karyolysus makariogeckonis sp. nov. These new taxa are further examples of endemic diversity in the Canarian archipelago. They also contribute to clarify the taxonomy within the Apicomplexa, a phylum estimated to have one of the lowest percentages of described species. [ABSTRACT FROM AUTHOR]

Enfermedad dual es la coexistencia al mismo tiempo de un trastorno adictivo y otro trastorno mental. El objetivo es estimar el cravingy la calidad de vida autopercibida en una muestra de pacientes con dependencia alcohólica, con o sin enfermedad dual, que acuden a un centro de tratamiento ambulatorio.

La edad del paciente ha sido clásicamente interpretada como un factor condicionante de la aparición de complicaciones postoperatorias en cirugía de resección pulmonar por carcinoma broncogénico. El Grupo de Estudio de Complicaciones Postoperatorias de la Sociedad Española de Cirugía Torácica promovió un registro que permitiera analizar este hecho.

The Persian Lizard, Iranolacerta brandtii, was until recently considered to be restricted to north-western Iran (Azerbaijan and Esfahan provinces). However, two recent studies have revealed the existence of populations in Eastern Anatolia, extending the range of this species for about 230 km westwards. The fragmented distribution of this species has been considered to be a consequence of the climatic oscillations during the Pleistocene and Holocene, which created events of alternating contact and isolation of populations in distinct glacial refugia. According to our obtained genealogy derived from three mitochondrial fragments (12S rRNA, 16S rRNA and cytb), the Turkish specimens cluster together but form an independent clade, sister to the individuals from Tabriz in Iran. The separation of these two clades is concurrent with the cladogenesis between the Esfahan and Ardabil clades, estimated to have taken place during the late Holocene.

Liposarcoma is a malignant neoplasm of mesodermal origin derived from adipose tissue. It most often originates in the extremities and retroperitoneum, and less frequently in the head and neck. Liposarcoma involving the chest wall is extremely rare with few reported cases. Surgery is the mainstay of treatment, and complete resection is the major factor influencing survival. We describe the case of a 65-year-old man diagnosed with a dedifferentiated liposarcoma of the chest wall, who underwent radical resection and chest wall reconstruction with a latissimus dorsi musculocutaneous flap.

The diet of three populations of semaphore geckos (Pristurus) from Socotra archipelago is analysed based on 82 faecal pellets. Pristurus samhaensisfrom the small islands of Samha (n= 18) and Darsa (n= 24) and P. sokotranusfrom the main island of Socotra (n= 40) were compared. Like other Pristurusspecies, P. samhaensison Samha and P. sokotranuson Socotra were highly myrmecophagous (76.7% and 38.6% ants, respectively). However, ants were absent from the diet of P. samhaensison Darsa. In contrast to the rich native ant fauna of the other islands, only one ant species was reported for Darsa, Pheidole teneriffana,likely a recently introduced species. Pristurus samhaensisseems to have overcome this scarcity in ant prey by consuming substitute prey, namely Coleoptera and Heteroptera, which are secondary for the other two populations studied. The two P. samhaensispopulations inhabiting the small islands displayed less diverse diets compared to that of P. sokotranusfrom the main island where vegetation structure was more complex. Prey items of P. samhaensisfrom Darsa were also smaller than those of P. sokotranusfrom Socotra, those of P. samhaensisfrom Samha being intermediate. It remains unclear how ancient these differences are, but they are probably too recent to have promoted special morphological and ecological adaptations in these geckos.

In many animals, chemical signals play an important role in species recognition and may contribute to reproductive isolation and speciation. The Iberian lizards of the genus Podarcis, with up to nine currently recognized lineages that are often sympatric, are highly chemosensory and provide an excellent model for the study of chemically mediated species recognition in closely related taxa. In this study, we tested the ability of male and female lizards of two sister species with widely overlapping distribution ranges (Podarcis bocageiand P. hispanicatype 1) to discriminate between conspecific and heterospecific mates by using only substrate-borne chemical cues. We scored the number of tongue flicks directed at the paper substrate by each individual in a terrarium previously occupied by a conspecific or a heterospecific lizard of the opposite sex. Results show that males of P. bocageiand P. hispanicatype 1 are capable of discriminating chemically between conspecifics and heterospecifics of the opposite sex, but females are not. These results suggest that differences in female, but not male, chemical cues may underlie species recognition and contribute to reproductive isolation in these species. The apparent inability of females to discriminate conspecific from heterospecific males, which is not because of reduced baseline exploration rates, is discussed in the context of sexual selection theory and species discrimination.In many animals, chemical signals play an important role in species recognition and may contribute to reproductive isolation and speciation. The Iberian lizards of the genus Podarcis, with up to nine currently recognized lineages that are often sympatric, are highly chemosensory and provide an excellent model for the study of chemically mediated species recognition in closely related taxa. In this study, we tested the ability of male and female lizards of two sister species with widely overlapping distribution ranges (Podarcis bocageiand P. hispanicatype 1) to discriminate between conspecific and heterospecific mates by using only substrate-borne chemical cues. We scored the number of tongue flicks directed at the paper substrate by each individual in a terrarium previously occupied by a conspecific or a heterospecific lizard of the opposite sex. Results show that males of P. bocageiand P. hispanicatype 1 are capable of discriminating chemically between conspecifics and heterospecifics of the opposite sex, but females are not. These results suggest that differences in female, but not male, chemical cues may underlie species recognition and contribute to reproductive isolation in these species. The apparent inability of females to discriminate conspecific from heterospecific males, which is not because of reduced baseline exploration rates, is discussed in the context of sexual selection theory and species discrimination.

Oukaïmeden Plateau is a herpetologically rich locality in the High Atlas (Morocco) where four lizard species coexist in strict sympatry: three lacertids (Lacerta perspicillata chabanaudi, L. andreanszkyiand Podarcis vaucheri– formerly P. hispanica vaucheri) and one gekkonid (Quedenfeldtia trachyblepharus). The diet composition of this lizard community during the early spring was analysed based on 132 faecal pellets which could be individually assigned to a species and a size and sex class. Quedenfeldtia trachyblepharushad the highest prey number and the most specialized prey composition based mainly on small Coleoptera (62.5 ) which were consumed in aggregates. All three lacertids displayed higher but similar levels of populational prey diversity. Lacerta p. chabanaudimainly fed on flying insects, whereas L. andreanszkyiand P. vaucherihad diets based on terrestrial prey. Larger lizards ate larger prey at both inter- and intraspecific levels. Species overlap was medium-high (48–84 ). Within species, P. vaucherishowed moderate segregation between males and females (74% overlap) whereas the other species did not (>94%). Pseudocommunity analyses revealed community structure based on segregation due to prey not consumed (species) and to the restriction of niche breadth (classes). The influences of species interactions on habitat use, restrictions in trophic availability and evolutionary history as determinant factors are discussed.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

In concentrated aqueous hydrobromic medium, Na[AuCl4] reacts with 1,6,7-trimethyllumazine (1,6,7-trimethyl-pteridine-2,4(1H,3H)-dione, MLMD) to give an adduct with simplified formula (H7O3)[AuBr4](DLMD)3in which the negative charge of the tetrabromoaurate(III) anion is neutralized by an oxonium dihydrate cation (H7O3+). The compound has been characterized by means of analytical techniques and IR and NMR spectroscopies. The crystals belong to the triclinic P—1 space group, with a= 11.321(1), b= 11.908(2), c= 16.460(1) Å, α = 71.54(2), β = 71.675(7), γ = 78.68(1)°, Z= 2, R= 0.089. The structure is formed by uncoordinated pteridine derivatives hydrogen-bonded, in a ladder-like polymeric fashion, to trinuclear oxonium-dihydrate cations; free square-planar tetrabromoaurate(III) anions are allocated in the holes of the H-bond network.

Lacertids are the dominant group of lizards throughout the Mediterranean Basin. Their role in food web transfer of matter and energy from arthropods and other small invertebrates to birds and mammals constitutes a major function within Mediterranean ecosystems. For many years, prey consumption by lacertids was thought to be almost indiscriminate, not much more than a byproduct of habitat use. However, increasing evidence does not support this passive view. Analyses of prey availability have revealed active prey selection/avoidance in several species. Others show an internal tendency (i.e., historical constraints) to consume specific animal items (ants, clumped prey) or plant matter (seeds, nectar, pollen, leaves). Behavioural experiments showed that lacertids not only identify different prey types by both visual and chemical cues but also modify their feeding behaviour integrating past experiences. Furthermore, size, sex, reproductive state, body condition, tail loss and probably other lizard features are relevant for feeding ecology. However, less attention has been devoted to abiotic factors such as temperature and humidity. More experimental studies of the influences of competitors, predators and parasites on diet are needed. Even though it is controversial, optimal foraging theory provides a conceptual background for future studies. The evolutionary history of the various lacertid lineages, which constrains their morphology and physiology and eventually produces exaptative traits, is to be considered as well. Finally, methodology in field sampling, lab work and statistical analysis needs to be developed. Recommendations are given as to when and where to sample, which compartment should be analysed, which is the appropriate sample size, how to assess trophic availability, which statistical descriptors should be used and how they should be compared.

The relative stabilities of potential tautomers, in both gas and aqueous phases, have been calculated taking into account the entropy effects over the tautomeric equilibria, in order to determine the structure and acid–base properties of the most stable tautomers of 2-thiolumazine in different pH conditions. In each medium, the tautomer with the lowest energy must be the most representative form at the corresponding pH. Knowledge of the effect of the medium in the tautomerization energies allows us to evaluate the possible effect of the medium on the molecular stability. Clearly, the results show that in the gas phase the basicity of the potential donor atoms is N5

Systematic excavations, begun in 1987, at the Valdegoba cave site in northern Spain have yielded the remains of five individuals associated with a Middle Paleolithic stone tool technology and Pleistocene fauna. A fragmentary mandible of an adolescent (VB1), preserving nearly a full set of teeth, exhibits a symphyseal tubercle and slight incurvatio mandibulae anterior on the external symphysis. Both the superior and inferior transverse tori are present on the internal aspect. A second individual (VB2) is represented by a set of ten deciduous teeth consistent with an age at death of 6–9 months. A proximal manual phalanx (VB3) displays a relatively broad head, a characteristic which is found in both Neandertals, as well as European Middle Pleistocene hominids. VB4 is a fourth metatarsal that lacks the distal epiphysis, indicating it comes from an adolescent individual, and has a relatively high robusticity index. Finally, VB5 is a fifth metatarsal of an adult. The VB1 mandible shows a combination of archaic characteristics as well as more specific Neandertal morphological traits. The VB2 deciduous teeth are very small, and both the metrics and morphology seem more consistent with a modern human classification. The postcranial elements are undiagnostic, U-Th dating has provided an age of >350ka for the base of the sequence and a date of <73·2±5ka for level 7, near the top. Faunal analysis and radiometric dates from other nearby Mousterian sites suggests that the Valdegoba site is correlative with oxygen isotope stages 3–6 on the Iberian peninsula, and an Upper Pleistocene age for the Valdegoba hominids seems most reasonable.

The crystal structures of fac-triaqua-(1,10-phenanthroline-N,N')-sulfato-manganese(II) (1) and tetraaqua-(1,10-phenanthroline-N,N')-manganese(II) sulfate dihydrate (2) are described. The coordination polyhedron around the Mn(II) ion displays a distorted octahedral shape and contains the N,N'-chelating phen ligand. In the first complex the coordination sphere is completed by three water molecules and a monodentate O-sulfato ligand (C3v), whereas in the second one, an uncoordinated sulfate ion (Td) and four coordinated water molecules have been found. In both structures, the molecular units are extensively 2-D hydrogen bonded, with the 1,10-phenanthroline ligands arranged roughly perpendicular to the sheets; the bidimensional sheets are piled up giving rise to polar layers made by the hydrogen bonded species, the aqua-ions, sulfate anions, and water molecules, alternated with apolar layers formed by the 1,10-phenanthroline ligands.

The synthesis and spectroscopic characterization of NiII, CuII, PdIIand AuIIIcomplexes containing hydrazones derived from 6-amino-5-formyl-1,3-dimethyluracil and thiosemicarbazide, acetylhydrazine and nicotinic acid is reported. In all cases, the complexes appear to be monomeric and square planar, with three positions occupied by the N,N,Z-tridentate (Z = S or O) ligand, making two five- and six-membered chelate rings and the fourth position occupied by halide.

Ab initio molecular orbital calculations at the RHF/6–31G* level using the GAUSSIAN94 program package have allowed us to simulate the molecular structures for different conformations of 6-amino-5-formyl-1,3-dimethyluracil-benzoylhydrazone. The contribution of the atomic orbitals of the potential donor atoms to the higher occupied molecular orbitals allows us to propose theoretical arguments to justify the different chelating behavior found for this compound in several metal complexes. Further, the molecular structure of 6-amino-5-formyl-1,3-dimethyluracil-benzoylhydrazone has been determined by single-crystal X-ray diffraction methods. The compound crystallizes in the monoclinic system (space group P21/n) with cell dimensions: a = 12.111(5), b = 5.743(5), c = 22.636(5) Å, β = 98.60(5)°. The structure was solved from 1719 reflections with I>2σ(I). The final R [I>2σ(I)] was 0.0506 for 217 parameters. The azomethine double bond substituents are in the E conformation and the N51 atom is in the cis position with respect to the N6 atom, due to the formation of an intramolecular hydrogen bond N6-H···N51. The geometrical data are in good agreement with those calculated by means of ab initio methods.

Abstract: A study of the relationship between the capillary column gas chromatographic retention times on two different columns (SE-54 and SE-52) for a group of trimethylsilyl ethers derived from 16 natural sterols found in olive oil and an initial set of 60 molecular descriptors was made. Three kinds of molecular descriptors were used: conventional, topological, and quantumchemical parameters. By using multivariable regression, two empirical functions for each column were obtained, which were selected on the basis of their respective statistical parameters. The first model relates the retention index with the quantum-chemical descriptors and the second with both topological and conventional descriptors. In all cases, the correlation coefficients of the empirical functions were higher than 0.9880, and the mean relative errors range between 2.88 and 3.24%. In any case, both models could be used, although the second model could be more useful and preferable because it has higher R 2 values and a lower standard error percentage, giving slightly more exact results.

In order to study from a theoretical point of view the coordinative properties and explain the reported N5,O4-chelating behaviour in several oxopteridine derivatives, semiempirical molecular orbital calculations were carried out on lumazine (pteridine-2,4(1H,3H)-dione), its N- and C-methylated derivatives, as well as their deprotonated and protonated forms using the PM3 hamiltonian as implemented in the hyperchem 4.0 package. The study of the partial charges over donor atoms does not allow us to justify the reported N5,O4-coordinating scheme, because some positive charge has been found on the N5 atom. Therefore, a more detailed analysis has been carried out taking into account the contributions of the AOs of each atom to the LCAO that defines each frontier MO. These calculations have confirmed the N5-O4 coordination mode of the neutral lumazine derivatives. The anionic forms could act as ligands in several ways, including the formation of either four- (N1-N8, N3-O4, N3-O2) or five-membered chelate rings (N5,O4). The experimental occurrence of only the latter coordination mode must be related to the higher stability of the five-membered chelate rings if it is compared with those of four and the possibility to establish p-M–N5 back-bonding.In order to study from a theoretical point of view the coordinative properties and explain the reported N5,O4-chelating behaviour in several oxopteridine derivatives, semiempirical molecular orbital calculations were carried out on lumazine (pteridine-2,4(1H,3H)-dione), its N- and C-methylated derivatives, as well as their deprotonated and protonated forms using the PM3 hamiltonian as implemented in the hyperchem 4.0 package. The study of the partial charges over donor atoms does not allow us to justify the reported N5,O4-coordinating scheme, because some positive charge has been found on the N5 atom. Therefore, a more detailed analysis has been carried out taking into account the contributions of the AOs of each atom to the LCAO that defines each frontier MO. These calculations have confirmed the N5-O4 coordination mode of the neutral lumazine derivatives. The anionic forms could act as ligands in several ways, including the formation of either four- (N1-N8, N3-O4, N3-O2) or five-membered chelate rings (N5,O4). The experimental occurrence of only the latter coordination mode must be related to the higher stability of the five-membered chelate rings if it is compared with those of four and the possibility to establish p-M–N5 back-bonding.

Single-crystal X-ray diffraction studies have been performed on the complex cis-diaqua-bis(1,3-dimethylpteridine-2,4(1H,3H)-dione-O4,N5) copper(II) perchlorate monohydrate, [Cu(DLM)2(H2O)2](ClO4)2· H2O. This compound crystallizes in the orthorhombic system, P212121space group, Z= 4 with a= 8.749(1) Å, b= 14.213(1) Å, c= 21.200(2) Å, and V= 2636.2(4) Å3. The metal ion is surrounded in octahedral geometry by two mutually quasi-perpendicular N5,O4-coordinated lumazine chelators with the O4 atoms transand the N5 atoms cis.The polyhedron is completed by two cis-coordinated water molecules. The absolute configuration of the complex can be described, following Bailar's nomenclature, as the enantiomer Λ of the stereoisomer 4M. A three-dimensional hydrogen-bond network is defined by water molecules, perchlorate anions, and the O2 of the pteridine A.

The crystal structure of bis-(6-amino-5-formyl-1,3-dimethyluracilato benzoylhydrazone)cobalt(II) dimethylformamide solvate is described. This compound crystallizes in the triclinic system, space group P1¯, Z= 2 with a= 9.7368(8), b= 12.346(1), c= 17.184(1) Å, α = 78.372(6), β = 74.585(6), γ = 71.113(5)°, and V = 1869.0(3) Å3. The coordination polyhedron around the metal ion displays a slightly flattened M(NNO)2octahedral shape. Both ligands bind in a trident fashion through the benzoylic oxygen atom, the hydrazone nitrogen atom closer to the uracil ring, and the deprotonated nitrogen atom of the amino group. The two ligands exhibit quite different conformations: one of them is almost planar, whereas the other is severely twisted.

A study of the relationship between the liquid chromatographic retention times for a group of 16 natural phenols on olive oil and an initial set of 62 molecular descriptors has been made. The descriptors used may be arranged into three well-defined kinds: conventional, topological, and quantum-chemical parameters. By using multivariate regression, three empirical functions were obtained, which were selected on the basis of their respective statistical parameters. The first model relates the retention index with the quantum-chemical descriptors; the second, with both topological and conventional descriptors; and finally, the third model has been established by considering the relation of the experimental magnitude with the two above-mentioned sets of parameters together. The correlation coefficients of the empirical functions were 0.9825, 0.9911, and 0.9974, with mean relative errors of 6.8, 4.6, and 2.6%, respectively.

In aqueous hydrobromic medium, Na[AuCl4] reacts with 1,3-dimethyllumazine (1,3-dimethyl-pteridine-2,4(1H,3H)-dione, DLM) or 1,3,6,7-tetramethyllumazine (DLMD) to give three adducts with simplified formulas Na[AuBr4](DLMD), Na[AuBr4](DLM), and Na[AuBr4](DLM)2. These compounds have been characterized by means of analytical techniques, and IR and NMR spectroscopies. Single-crystal x-ray diffraction studies have been made on the Na[AuBr4](DLM)2compound. The crystals belong to the orthorhombic Pbca space group, with a= 15.249(1), b= 15.238(2), c= 21.563(2) Å, Z= 8, and R= 0.053. The structure consists of planar [AuBr4]−anions and Na+cations weakly linked to two crystallographically independent DLM molecules. The Na+cation interacts weakly with four oxygen and one nitrogen atoms from four different pteridine molecules, its environment may be described as a very distorted square pyramid.

The coordinative capacity of 2-benzylthio-4-formyl-1-p-methoxyphenylimidazole (ALME) with several transition metal ions has been investigated and has led to only copper(II) and cadmium(II) complexes of general formula [MIICl2(ALME)2]·nH2O. These compounds were studied by spectral (i.r., u.v.-vis. n.i.r. and e.p.r.) and thermal methods (t.g., d.t.g. and d.s.c.) as well as magnetic susceptibility measurements.

In absolute ethanol medium, copper(II) nitrate reacts with 6-amino-1,3-dimethyl-5-nitrosouracil (HDANU) and 2,2′-bipyridine to give a mixed complex with the formula [Cu(DANU)(bipy)(EtOH)](NO3). This compound has been characterized by means of analytical techniques (elemental analysis and TG), spectral methods (IR, UV-VIS-NIR, EPR), magnetic measurements (77–290 K) and single-crystal X-ray diffraction. The structure consists of monomeric CuN4O units in which the copper ion displays a 4 +1 square-pyramidal coordination. The base of the polyhedron is occupied by four nitrogen atoms (Cu-N ca 2 , two from bipy and the other two from 5-nitroso and 6-amino groups of the uracil derivative in the N6-mono-deprotonated form, leaving two five-membered chelate rings. In the apical position of the pyramid, an O-coordinated ethanol molecule with a long Cu-O distance (2.248 ) is located, the metallic centre being 0.144above the base of the polyhedron. The nitrate group is out of the coordination sphere, stabilizing the complex by hydrogen bonds formed between the hydrogen atom attached to the ethanolic oxygen and an oxygen atom from the nitrate group. The molecules are stacked as planes perpendicular to the a axis. Copyright © 1996 Elsevier Science Ltd

The crystal structure of [Fe(H2isoor)2(H2O)2]·2H2O has been solved by single-crystal X-ray diffractometry. Thermogravimetric analysis shows simultaneous loss of all water molecules between 120 and 266°C, followed immediately by a rapid degradation of the compound. A comparative analysis of the Raman spectra of the complex with that of free-iso-orotic acid allowed a straightforward assignment of the vibrations of the ligand groups involved in coordination. The 57Fe Mo¨ssbauer spectrum of the complex confirms the presence of a high-spin FeII ion and the distortion of the octahedral FeII environment.

From the reaction of isoorotic and 2-thioisoorotic acids with AgI, PdII, PtII and PtIV ions, twelve new complexes containing the uracil ligand in either monoor dianionic forms have been isolated and studied by conductivity measurements, i.r. and n.m.r. spectroscopies, and by thermal methods (t.g. and d.s.c.). From the data obtained, tentative molecular structures are suggested for each complex. The most common coordination mode of both acids involves formation of a six-membered chelate ring through the exocyclic O(4) atom and an oxygen of the carboxylate group. The antimicrobial activity of these compounds against several bacteria and yeast has also been assayed. It is noticeable that PdCl(H2CU)py complex is active againstPseudomonas sp. andMicrococcus sp. at MIC values lower than 50 µg cm-3.

In absolute methanol medium, eight new 1:1 metal complexes of general formula MIIX2L·nH2O have been isolated (L=1,3–dimethyllumazine (DLM) or 1,3,6,7–tetramethyllumazine (DLMD) ; M=Cu, Cd, Hg, Pd and Pt; X=Cl−or NO−3) . The experimental techniques used for their structural characterization were thermal (TG and DSC) and spectral methods (IR, 13C and 1H–NMR and EPR) and magnetic measurements (77–290 K) . Single-crystal X-ray diffraction studies have been performed on the complexes [CuCl2(DLMD) (H2O) ] ·H2O (1) , [HgCl2(DLMD) ] (2) and [HgCl (NO3) (DLMD) ] (3) . In all the complexes, the lumazine-derived ligands seem to be coordinated in bidentate form through the N5 and O4 atoms. The complex 1 shows a monomeric five-coordinated structure in which the coordination polyhedron can be best described as a trigonal bipyramid. The equatorial plane is occupied by two chlorine atoms (Cu–Cl 2.268 and 2.261 Å) and an oxygen O (4) from the organic ligand (Cu–O (4) 2.294 Å) , whereas the apical positions were designed by a coordinated water molecule and the N (5) atom of the bidentate pteridine ligand (Cu–O (1W) 1.950 Å and Cu–N (5) 2.038 Å) . The crystal structure is conformed by an extense hydrogen bonds scheme in which the non-coordinated water molecule plays an important role. In the compound 2, the pteridine ligand interacts only weakly with the Hg (II) ion (Hg–O (4) 2.772 Å and Hg–N (5) 2.675 Å) ; the structure must be described as an adduct between the HgCl2and the organic ligand in which the molecules of metallic salt retain their identity (Hg–Cl 2.284 and 2.288 Å) . These units are weakly paired through long interactions of each metal centre with chloride ions of a neighbour molecule (Hg···Cl 3.664 Å) . The mixed complex 3 displays a polymeric structure in which the nitrate groups act as bridging bifurcate ligands between two Hg (II) ions through only one of their three oxygen atoms. The coordination polyhedron around the Hg (II) ion must be described as a trigonal bipyramid in which the metal is surrounded by the O (4) , O (1N) and O (1N′) atoms in the equatorial plane at distances of 2.551, 2.563 and 2.618 Å, respectively. In the axial positions, a terminal chloride ligand (Hg–Cl (1) 2.307 Å) and the N (5) atom of pteridine ligand (Hg–N (5) 2.208 Å) can be found.

In absolute methanol, copper(II) nitrate reacted with 1,3-dimethyl-(1H, 3H)-pteridin-2,4-dione (1,3-dimethyllumazine, DMLM) giving a complex with formula [Cu(DMLM)2(H2O)2] (NO3)2 · 2H2O. This compound has been characterized by means of analytical techniques (elemental analysis and TG), spectral methods (IR, UV-vis-NIR, EPR), magnetic measurements (77–290 K) and single-crystal X-ray diffraction. The copper(II) ion occupies an inversion centre and exhibits an elongated octahedral coordination. The equatorial plane consists of two N(5) atoms of the pteridine ligands and two oxygen atoms from water molecules, and the two axial sites are occupied by two O(4) atoms of the ligands. The non-coordinated water molecules and nitrate anions, as well as the pteridine ligands are involved in a two-dimensional H-bond network, the metal-pteridine moieties being linked to the non-coordinated water molecules and nitrate anions of neighbouring molecules through the O(2) atom of the pteridine ligands. The molecules are packed in planes parallel to the b-axis, these planes being stacked at a mean distance of 3.297A˚to each other. A three-dimensional arrangement is defined by the involvement of the coordinated water molecules in a hydrogen bond with one oxygen atom from the uncoordinated water and another oxygen from the nitrate group of the adjacent layers.

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