Dr. Hofmann on Phospharsonium Compounds, 245 



"Researches on the Phosphorus-Bases." — No. IX. Phosphar- 

 sonium Compounds. By A. W. Hofmann, LL.D. Received 

 July 24, 1860. 



The facility with which the bromide of bromethyl-triethylphos- 

 phonium furnishes, when submitted to the action of ammonia and 

 monamines, the extensive and well-defined group of phosphammo- 

 nium- compounds, induced me to try whether similar diatomic bases 

 containing phosphorus and arsenic might be formed by the mutual 

 reaction between the bromethylated bromide and monarsines. There 

 was no necessity for entering into a detailed examination of this class 

 of compounds. I have, in fact, been satisfied to establish by a few 

 characteristic numbers the existence of the phospharsonium-group. 



Action of Triethylarsine on Bromide of ' Bromethyl-triethyl- 

 phosphonium. 



On digesting the two substances in sealed tubes at 1 00°, the usual 

 phenomena are observed ; the reaction being complete after the lapse 

 of twenty-four hours. The saline mass which is formed yields with 

 oxide of silver in the cold, a powerfully alkaline solution, containing 

 the hydrated oxide of ethvlene-hexethylphospharsonium, 



C,.H„PA s O a =K C » H «>"^ H »)« P t ] "o, 



It is thus obvious that the arsenic- base imitates triethylphosphine 

 in its deportment with the brominated bromide. The two substances 

 simply combine to form the dibromide of the phospharsonium, 



[(C 2 H 4 Br) (C, H 5 ) 3 P] Br + (C 2 H 5 ) 3 As= [(C, H 4 )» g ^ £J 'W 2 



The alkaline solution of the oxide of the phospharsonium exhibits 

 the leading characters of this class of bases ; I may therefore refer 

 to the account which I have given of the oxide of diphosphonium, 

 The saline compounds likewise resemble those of the diphosphonium. 

 The dichloride and the di-iodide were obtained in beautiful crystalline 

 needles, exhibiting a marked tendency to form splendidly crystallized 

 double compounds. I have prepared the compounds of the dichlo- 

 ride with chloride of tin, bromide of zinc, trichloride of gold, and 

 lastly with dichloride of platinum. The latter compound was ana- 

 lysed in order to fix the composition of the series. 



Platinum- salt. — The product of the reaction of triethylarsine 

 upon the bromethylated bromide was treated with oxide of silver in 

 the cold, and the alkaline solution thus obtained, saturated with 

 hydrochloric acid and precipitated with dichloride of platinum. An 

 exceedingly pale-yellow, apparently amorphous precipitate of diphos- 

 phonic appearance was thrown down, almost insoluble in water, but 

 dissolving in boiling concentrated hydrochloric acid. The hydro- 

 chloric solution deposited, on cooling, beautiful orange-red crystals, 

 resembling those of the diphosphonium-platinum-salt. The crystals, 

 according to the measurement of Quintino Sella, belong to the tri- 



