Spin-Crossing in the ()-Selective Alkyne Semihydrogenation Mechanism Catalyzed by MoS Clusters: A Density Functional Theory Exploration.

Semihydrogenation of internal alkynes catalyzed by the air-stable imidazolyl amino [MoSCl(ImNH)] cluster selectively affords the ()-alkene under soft conditions in excellent yields. Experimental results suggest a sulfur-based mechanism with the formation of a dithiolene adduct through interaction of the alkyne with the bridging sulfur atoms. However, computational studies indicate that this mechanism is unable to explain the experimental outcome: mild reaction conditions, excellent selectivity toward the ()-isomer, and complete deuteration of the vinylic positions in the presence of CDOD and CHOD.

Fe(II) complexes of pyridine-substituted thiosemicarbazone ligands as catalysts for oxidations with hydrogen peroxide.

The reaction of three [Fe(TSC)] complexes, where TSC is a pyridine-substituted thiosemicarbazone of the HDpT or HBpT families, with HO in acetonitrile solution does not result in the accumulation of the corresponding [Fe(TSC)] complexes. Instead, a mixture of diamagnetic low-spin Fe species is generated. According to the MS spectra, those species result from the sequential addition of up to five oxygen atoms to the complex.

Metal bioaccumulation in spontaneously grown aquatic macrophytes in Fe-rich substrates of a passive treatment plant for acid mine drainage.

Some plants may thrive in polluted environments, accumulating high concentrations of metal/loids in their organs. This study investigates for the first time the bioaccumulation and translocation of metal/loids in Typha domingensis spontaneously grown in extremely Fe-rich substrates (38-44% of FeO) from different components of an acid mine drainage disperse alkaline substrate passive treatment. Most metal/loids were predominantly accumulated in the roots over the aerial parts of the plant, with concentrations of 0.

Metal mobility and bioaccessibility from cyanide leaching heaps in a historical mine site.

Unlike acidic sulfide mine wastes, where metal/loid mobility and bioaccessibility has been widely studied, less attention has been paid to alkaline cyanide heap leaching wastes. Thus, the main goal of this study is to evaluate the mobility and bioaccessibility of metal/loids in Fe-rich (up to 55%) mine wastes resulting from historical cyanide leaching activities. Wastes are mainly composed of oxides/oxyhydroxides (i.