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[EN] The research performed exhaustive experiments to help better understand how subterranean termite colonies function in their biodegradation activity in wooden structural elements. Specifically, the research had as main objectives to analyse the usefulness of CO2 as a bioindicator of the presence of termites and their wood biodegradation activity. The obtained results have demonstrated that CO2 emissions of termite colonies vary depending on their wood degradation activity. So, the amount of CO2 emitted is closely linked to the population size and activity levels. The obtained relationship between the CO2 concentration and time for different population sizes can predict termite biodegradation severity and help establish predictive models for pest monitoring in wood structures.

Correspondence: Maria Teresa Cabria, Fax: (+34) 945013014; (+32) 43663847; E-mail: maitec79@yahoo.es; International audience; Human-mediated global change will probably increase the rates of natural hybridization and genetic introgression between closely related species, and this will have major implications for conservation of the taxa involved. In this study, we analyse both mitochondrial and nuclear data to characterize ongoing hybridization and genetic introgression between two sympatric sister species of mustelids, the endangered European mink (Mustela lutreola) and the more abundant polecat (M. putorius). A total of 317 European mink, 114 polecats and 15 putative hybrid individuals were collected from different localities in Europe and genotyped with 13 microsatellite nuclear markers. Recently developed Bayesian methods for assigning individuals to populations and identifying admixture proportions were applied to the genetic data. To identify the direction of hybridization, we additionally sequenced mtDNA and Y chromosomes from 78 individuals and 29 males respectively. We found that both hybridization and genetic introgression occurred at low levels (3% and 0.9% respectively) and indicated that hybridization is asymmetric, as only pure polecat males mate with pure European mink females. Furthermore, backcrossing and genetic introgression was detected only from female first-generation (F1) hybrids of European mink to polecats. This latter result implies that Haldane’s rule may apply. Our results suggest that hybridization and genetic introgression between the two species should be considered a rather uncommon event. However, the current low densities of European mink might be changing this trend.

The complex [{AuTl(C6Cl5)2(toluene)} 2(dioxane)] displays a structure with the thallium(I) center in an unprecedented trigonal planar environment, showing the shortest Au-Tl interaction ever found, a toluene molecule in a 6-mode and the "disappearance" of the Tl(I) inert pair, usually stereochemically active. These characteristics are responsible for its unusual luminescent behaviour.

The reaction of the asymmetric ligand 2-(diphenylphosphino)aniline (PNH2) with gold(I), silver(I) or copper(I) substrates in various molar ratios leads to the complexes [M(PNH2)2]A (M = Au, A = TfO (1); M = Ag, A = TfO (2), ClO4 (3); M = Cu, A = TfO (4)), the homodinuclear derivatives [M(PNH2)]2A2 (M = Ag, A = TfO (7), ClO4 (8); M = Cu, A = TfO (9)) or [M(PNH2)3]A (M = Au, A = TfO (12); M = Ag, A = ClO4 (13); M = Cu; A = TfO (14)). Reaction of [AuCl(PNH2)] with AgClO4 (1:1) in acetone causes the ligand to condense with the solvent, resulting in the synthesis of [Au(PN=CMe2)]2(ClO4)2 (5). Treatment of the gold(I) compound 1 with the same silver(I) or copper(I) starting materials as before gives the heteronuclear species [AuM(PNH2)2](TfO)2 (M = Ag (10); M = Cu (11)). The optical properties of some of these complexes have been studied and the crystal structures of compounds 5, 10 and 12 have been determined by X-ray diffraction.

The dinuclear head-to-tail complexes [M2(PPh2CH2SPh)2]2- (M = Cu (1), Ag (2a, 2b), Au (4)) are obtained either by reaction of [Cu(CH3CN)4]CF3SO3, AgClO4, AgCF3SO3, with equimolecular amounts of PPh2CH2SPh or of [AuCl(PPh2CH2SPh)] (3), prepared by reaction of [AuCl(tht)] and PPh2CH2SPh, with AgCF3SO3. The crystal structures of complexes 2a and 4 have been established by X-ray diffraction studies. Ab initio HF/II and MP2/II calculations have been performed on the [M2(H2PCH:SH)2]2+ model, indicating that metallophilic attraction is indeed present for all the coinage metals as a correlation effect and is strengthened in the case of gold by relativistic effects. Since experimental and theoretically predicted geometries are in close agreement, we assume that our calculations are accurate enough to obtain valid conclusions.

Treatment of vinylidenebis(diphenylphosphine) with elemental sulfur under reflux led to vinylidenebis(diphenylphosphine) disulfide, (SPPh2)2C=CH2, in good yields. Its co-ordination to a gold(III) centre activates the carbon-carbon double bond. Thus, the chelate complex [Au(C6F5)2{(SPPh2) 2C=CH2}]ClO4 reacted rapidly with carbon- or oxygen-donor nucleophiles (Nu-), such as acac- (acetylacetonate), CN-, C5H5 - or OEt-, forming methanide-type derivatives [Au(C6F5)2{(SPPh2) 2CCH2Nu}]. These products can be considered as intermediates in Michael-type additions of HNu to the C=C bond, which in this particular case display high stabilities, allowing their isolation as solids. The crystal structure of the cyclopentadienyl derivative has been established by X-ray crystallography and displays a square-planar gold(III) centre with a cis disposition of the pentafluorophenyl groups and sulfur atoms of the chelating ligand, and sp2 hybridization of the endocyclic carbon atom with partial P-C double-bond character.

The reaction of [Au(tht)2]ClO4 or NBu4[Au(acac)2] with 2 equiv of [Au(C6F5)3PPh2CH 2-PPh2] affords the cationic [{Au(C6F5)3PPh2CH 2PPh2}2Au]ClO4 (1) or anionic complex NBu4[{Au(C6F5)3PPh 2CHPPh2}2Au] (2), respectively, in high yield. The methanide complex 2 can displace tetrahydrothiophene from [AuX(tht)] to give the pentanuclear NBu4[{Au(C6F5)3-PPh 2CH(AuX)PPh2}2Au] (X = Cl, C6F5). The heptanuclear [{Au(C6F5)3PPh2C(AuPPh 3)2-PPh2}2Au]ClO4 is obtained by reaction of 1 with [Au(acac)PPh3] (molar ratio 1:4). The structure of 2 has been determined by a single-crystal X-ray diffraction study. It crystallizes in the space group P1 with a = 14.213(4) Å, b = 16.067(4) Å, c = 23.840(6) Å, = 88.60(2)°, = 89.27(2)°, = 71.23(2)°, Z = 2, and T = -100°C. It does not display gold-gold interactions. © 1995 American Chemical Society.