9 research outputs found
(Electro)chemical N<sub>2</sub> Splitting by a Molybdenum Complex with an Anionic PNP Pincer-Type Ligand
Molybdenum(III) complexes
bearing pincer-type ligands
are well-known
catalysts for N2-to-NH3 reduction. We investigated
herein the impact of an anionic PNP pincer-type ligand in a Mo(III)
complex on the (electro)chemical N2 splitting ([LMoCl3]−, 1–, LH = 2,6-bis((di-tert-butylphosphaneyl)methyl)-pyridin-4-one). The increased electron-donating
properties of the anionic ligand should lead to a stronger degree
of N2 activation. The catalyst is indeed active in N2-to-NH3 conversion utilizing the proton-coupled
electron transfer reagent SmI2/ethylene glycol. The corresponding
Mo(V) nitrido complex 2H exhibits similar catalytic activity
as 1H and thus could represent a viable intermediate.
The Mo(IV) nitrido complex 3– is also accessible by electrochemical reduction of 1– under a N2 atmosphere. IR- and UV/vis-SEC
measurements suggest that N2 splitting occurs via formation
of an “overreduced” but more stable [(L(N2)2Mo0)2μ-N2]2– dimer. In line with this, the yield
in the nitrido complex increases with lower applied potentials
Introduction or reintroduction? Last resorts for the latest bird to become extinct in Europe, the Andalusian hemipode Turnix sylvatica sylvatica
The Andalusian hemipode (Turnix sylvatica sylvatica) (Order: Turniciformes, Family: Turnicidae), formerly distributed in several Mediterranean countries, is a critically endangered bird, if not already extinct. Subspecies of the T. sylvatica complex, in turn composed by nine subspecies are widely distributed in Africa and southern Asia. The last free-ranging Andalusian hemipodes were shot by hunters near Donana National Park (Spain) in 1981. Therefore, this species could be the last bird species getting extinct in Iberia and Europe in the XXth century. This investigation deals with the phylogenetic relationships of the Andalusian hemipode with the sup- posedly congeneric T. varia, T. tanki, T. suscitator and T. pyrrhothorax, and with the supposedly conspecific T. sylvatica lepurana, which is the geographically nearest buttonquail population (occurring in central and southern Africa). A 606 bp long fragment of the cytochrome b gene (approx. 1140 bp) of the mitochondrial DNA was sequenced, using both museum skins (the only available source for T. s. sylvatica) or blood/tissue samples from contemporary individuals (remaining species and subspecies). Seven haplotypes were found: two each for T. varia and T. s. lepurana, and one each for T. tanki, T. suscitator, T. pyrrhothorax, and T. s. sylvatica. Sequence divergence values obtained from pairwise distances between the T. sylvatica group haplotypes and the other species, ranged from 19.4 to 25.9%. The low genetic divergence between T. s. sylvatica and T. s. lepurana (0.00–0.01%) confirmed that the current classification based on morphological characters is correct, and that these two taxa may should be considered as subspecies. This close relationship would permit an introduction T. sylvatica where the species was last seen in Spain (i.e., Donana National Park). This area is now strictly protected and human persecution is no longer a problem.Peer reviewe