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Phosphorus
Published in Robert H. Kadlec, Treatment Marshes for Runoff and Polishing, 2019
Gaseous forms of phosphorus, phosphine (PH3), and diphosphine (P2H4), are known to exist. These are in some sense analogous to hydrogen sulfide, in that they form in low redox conditions, are volatile, and are extremely toxic. Phosphine is soluble in water, but has a high vapor pressure. It may be emitted from regions of extremely low redox potential, together with methane. It has been reported that the methane-phosphine mixture emitted from marshes and bogs can auto-ignite, forming the flickering lights known as “Will-o’-the-wisp”. In the early 20th century, there were reports of failure to find these compounds, which are now thought to be the result of flawed analytical procedures. Burford and Bremner (1972) found that formation of phosphine could not be excluded on thermodynamic grounds.
Amination of aliphatic alcohols with urea catalyzed by ruthenium complexes: effect of supporting ligands
Published in Journal of Coordination Chemistry, 2020
Sara Dindar, Ali Nemati Kharat
Complex 1 showed higher catalytic activity than 2 (entries 3 and 4 in Table 3). It was proposed that catalytic dehydrogenation of alcohols can be facilitated by an electron-rich metal center. Therefore, bidentate phosphine ligand has been found to have a stronger effect, perhaps due to the higher basicity and stronger coordination ability compared to mono phosphine ligand, PEt2H. Among the ruthenium complexes with diphosphine ligands, the selectivity was likely controlled by the strict environment around the metal center (entries 9–12 in Table 3). cis-[RuCl2(dppp)2] showed the best activity in this group of catalysts. The selectivity of the complexes depends on the ligand's size, as smaller diphosphines (dppm and dppe) showed higher selectivity for primary amines while increasing the bridge length for bulky diphosphine (dppp and dppb) leads to higher selectivity for secondary amines. From the experimental results we chose 3 mol% of catalyst as the optimum value for proper conversion, while, with increasing the amount of catalyst, no positive effect on the reaction conversion was obtained (entry 13).
Phosphine-substituted diiron 1,2-dithiolate complexes as the models for the active site of [FeFe]-hydrogenases
Published in Journal of Coordination Chemistry, 2019
Lin Yan, Jiao He, Xu-Feng Liu, Yu-Long Li, Zhong-Qing Jiang, Hong-Ke Wu
X-ray diffraction analysis has confirmed the structures of 2–6 in the solid state. While the ORTEP views are shown in Figures 2–6, the selected bond distances and angles are provided in Table 2. Complexes 2, 3, and 5 crystallize in the triclinic crystal class, whereas 4 and 6 crystallize in the monoclinic crystal class. As shown in Figures 2–6, 2–6 consist of a 1,2-dithiolate-bridged diiron cluster coordinated by five terminal carbonyls and a phosphine ligand. The phosphine ligands reside in an apical position of the distorted octahedral coordination sphere of the Fe atom, in good agreement with the known phosphine-substituted diiron analogues [43–47], but different from those containing intramolecular bridging or chelating diphosphine ligands [48–51]. The Fe1‒Fe2 bond distances of 2 [2.5109(4) Å], 4 [2.5082(7) Å], 5 [2.5071(6) Å] and 6 [2.5213(4) Å] are slightly longer than that of 1 [2.505(2) Å] [52]. However, the Fe1‒Fe2 bond distance of 3 [2.4991(5) Å] is slightly shorter than that of 1, probably due to the different electron-donating properties of the phosphine ligands. The Fe1‒Fe2 bond distances in 2–6 are remarkably shorter than those in natural [FeFe]-hydrogenases [11, 12] as well as those in disubstituted complexes [53, 54]. It is worth pointing out that Cl2 and Cl3 are disordered over two sites with occupancies of 0.51 and 0.512 in 4.
Extraction of lanthanides(III) from Perchlorate Solutions with Carbamoyl- and Phosphorylmethoxymethylphosphine Oxides and Tetrabutyldiglycolamide
Published in Solvent Extraction and Ion Exchange, 2019
A. N. Turanov, V. K. Karandashev, A. V. Kharlamov, N. A. Bondarenko, V. A. Khvostikov
Solvent extraction is a widely used technique for the separation and preconcentration of metal ions in biphasic water/organic solvent systems.[1] Neutral bidentate organophosphorus compounds such as arylsubstituted methylene diphosphine dioxides (DPDO) and diaryl- or alkyl(aryl)[dialkylcarbamoylmethyl]phosphine oxides (CMPO) are known to be efficient extractants for the separation and preconcentration of actinides and lanthanides from nitric acid solutions.[2–4] The extraction ability of neutral bidentate organophosphorus compounds is higher than that for their monodentate analogs.[5,6] It was showed that compounds containing P(O)CH2P(O) and P(O)CH2C(O) moieties with aryl substituents at the phosphorus atom were superior to alkyl-substituted ones in their ability to extract trivalent lanthanides and actinides from HNO3 solutions.[7,8] Rosen et al.[7] refer to this phenomena as anomalous aryl strengthening (AAS) effect. The reasons of this effect were discussed in.[8–14]