The dicationic complexes [IndCpMoL2]2+ (Ind = indenyl; Cp = cyclopentadienyl; 1, L2 =
dppe; 2, L = PMe3; 4, L2 = Bipy; 5, L2 = tBu2bipy; 6, L2 = H2biim; 7, L = CO and CNMe; 8,
L = CNMe; 9, L = CNtBu; 10, L = NCMe and NMF; 11, L = NMF) were synthesized from
[IndCpMoL‘2]2+ (L‘ = CO, NCMe), [IndCpMo(NCMe)Cl]BF4, or IndCpMoCl2 by ligand
substitution. The neutral complexes (η3-Ind)CpMoL2 (13, L2 = dppe; 14, L = PMe3; 15, L2 =
Bipy; 16, L = CO and CNMe; 17, L = CNtBu) were obtained upon reduction of the respective
dications with Cp2Co. (η
3-Ind)CpMo(dppe) (13) was also prepared by deprotonation of the
cyclopentadiene cation [IndMo(η4-C5H6)(dppe)]BF4
(12) with NEt3. The cyclic voltammograms
of the dications present one reversible 2e reduction step from Mo(IV) to Mo(II) except for 1,
2, and 6, in which cases two reversible 1e waves are observed. The ring-slipped complexes
(η
3-Ind)CpMoL2 and the parent dications present similar CV's. The X-ray crystal structures
of [IndCpModppe][BF4]2 and (η
3-Ind)CpMo(dppe) confirm the indenyl ring planar η5
coordination and slip-folded η3, respectively.
To analyze the influence of environmental heterogeneity on heavy metal exposure concentrations for terrestrial vertebrates in river floodplains, a spatially explicit exposure model has been constructed (SpaCE-model: Spatially explicit cumulative exposure model). This model simulates the environmental use of individual organisms by selecting model cells to be foraged in within a multicelled, heterogeneous landscape. Exposure durations and exposure concentrations are calculated for the selected cells, whereby exposure concentrations are dependent on the availability and contaminant concentrations of different diet items in each cell. The model was applied to a selection of 10 terrestrial vertebrate species, including six small mammalian and four top predator species. It was parameterized for cadmium contamination in a 285-ha, embanked floodplain area along the Rhine River in The Netherlands. Simulations of 1,000 individuals for each species resulted in intraspecies variation in exposure concentrations of between 11 and 39%, with the smallest values generally corresponding to the species with the largest home ranges. Comparison of the model results with cadmium concentrations measured in four of the species from the study area showed that the predicted variation accounted for 12 to 16% of the variation in the measurements. This indicates that environmental heterogeneity governs a minor part of the variation in metal exposure concentrations that can actually be observed in river floodplains.
Reaction of Re2{μ‐O2CC(CH3)3}4Cl2 with [(CO)5M–CN]Na (M = Cr, Mo, W) leads to tetranuclear complexes of formula Re2{μ‐O2CC(CH3)3}4[–NC–M(CO)5]2 (M = Cr, Mo, W). These complexes were characterized by 1H‐, 13C‐, and 95Mo‐NMR, IR and Raman spectroscopy, elemental analysis and examined by cyclic voltammetry. The applied methods show the donor capabilities of the [(CO)5M–CN]− ligands which shift electron density towards the Re centers weakening the Re–Re quadruple bond. The Re–Re bond lengths and the ν(Re–Re) force constants are estimated based on the FT‐IR and Raman examinations. Photochemical examinations and TG/MS experiments have also been conducted. The latter method shows that the product complexes decompose around 100 °C, by first loosing their carbonyl substituents; as do the Cr, Mo, W precursor compounds. The dirhenium tetrapivalate unit decomposes only at higher temperatures in a distinct second step.
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