Arsenic pentachloride, instability

Arsenic pentachloride, instability of, 7 7-8 Arsenic pentafluoride, 7 2, 4, 5 chalcogen(IV) compound adducts, 35 259-261... 

Arsenic pentachloride can be prepared at low temperature but decomposes above —50°C. Antimony pentachloride is made by reaction of Cl2 with SbCl3 and is stable up to 140°C. The solid (mp 4°C) contains Cl4Sb(/x-Cl)2SbCl4 dimers. The curious instability of AsC15 relative to PC15 and SbCl5 has been attributed to a stabilization of the 4s2 electron pair in all the elements immediately following the... 

Tetrakis(phenyldifluorophosphine)nickel-(0) could also be obtained, using arsenic trifluoride in the presence of catalytic amounts of antimony pentachloride, or zinc fluoride as fluorinating agents. Yields as high as 50% could be obtained, but sizable decomposition on the process of fluorination of the chlorophosphine nickel-(0) complexes in solution could not be entirely suppressed. The marked instability of zerovalent nickel-phosphine complexes in solution in organic solvents, even under strictly anhydrous and anaerobic conditions, has been noted by several workers (16,20), but is still lacking a detailed explanation. A closer examination of the system carbon tetrachloride-tetrakis(trichlorophosphine)nickel-(0) (23) showed the main pa h of the reaction to consist in the formation of hexachloro-ethane with conversion of zerovalent into bivalent nickel, while the coordinated... 

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