Arsenic—hydrogen bonds

Miscellaneous.—Polytertiary phosphines and phosphinoarsines have been prepared by the base-catalysed addition of phosphorus-hydrogen or arsenic-hydrogen bonds to vinylphosphines or ethynylphosphines. The same type of reaction was utilized to prepare the diphosphine (13). Radical addition of primary phosphines to vinylphosphines has also been... 

Trialkyl- and triarylarsine sulfides have been prepared by several different methods. The reaction of sulfur with a tertiary arsine, with or without a solvent, gives the sulfides in almost quantitative yields. Another method involves the reaction of hydrogen sulfide with a tertiary arsine oxide, hydroxyhahde, or dihaloarsorane. X-ray diffraction studies of triphenylarsine sulfide [3937-40-4], C gH AsS, show the arsenic to be tetrahedral the arsenic—sulfur bond is a tme double bond (137). Triphenylarsine sulfide and trimethylarsine sulfide [38859-90-4], C H AsS, form a number of coordination compounds with salts of transition elements (138,139). Both trialkyl- and triarylarsine selenides have been reported. The trialkyl compounds have been prepared by refluxing trialkylarsines with selenium powder (140). The preparation of triphenylarsine selenide [65374-39-2], C gH AsSe, from dichlorotriphenylarsorane and hydrogen selenide has been reported (141), but other workers could not dupHcate this work (140). 

The quite different isotope effects in the dihydrogen salts of the phosphates and arsenates, shown in Fig. i, suggest that there hydrogen bonds are different in some way. It has been shown that the potential energy curve for the Ox—H 0IX bond in KH2P04 possesses two... 

The application of SPE has partially eliminated the above problems, particularly in the case of arsenic concentration in water samples [123]. SPE delivers better selectivity than LEE because it can be used to sequentially elute compounds from the activated carbon bed, and to separate inorganic compounds of As(III) and As (V), as well as the phenyl (PAS) and dimethyl (DMA) derivatives of arsenic (V) acid [124]. The extraction process is short, which is why it is possible to directly coimect the SPE module with the ICP MS detector [125]. Whenever modified silica is used, arsenic recovery is low (even below 50 %) owing to the formation of hydrogen bonds between the substances being separated and silanol groups [114, 126, 127]. 

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