TOO 



II. " Researches on the Phosphorus-Bases." No. VI. Phos- 

 phammonium-Compounds. By A. W. HOFMANN, LL.D., 

 F.R.S. &c. Received June 1, 1859. 



In several previous communications * I have shown that dibromide 

 of ethylene is capable of fixing either one or two molecules of tri- 

 ethylphosphine, a monatomic and a diatomic bromide being formed, 

 which I have respectively represented by the formulae 



Monatomic bromide. 



C lfl H 19 PBr 2 = (C 4 H 4 )" Br 2 + (C 4 H 5 ) 3 P= 



SH; 1 



*~* 



.(cU'Br)] j 



and 



Diatomic bromide. 



C M H 34 P 2 Br 2 = (C 4 H J" Br 2 -f 2 ((C 4 H 5 ) 3 P) = 



Br 



Br 



There are other products formed, resulting from secondary reactions. 



It was not quite easy to obtain a sufficiently satisfactory experi- 

 mental foundation for the diatomic nature of the second compound. 

 This substance presents an extraordinary degree of stability ; in its 

 general characters it is closely allied to the numerous monatomic 

 bromides, both of the nitrogen- and of the phosphorus-series, which 

 in the course of these researches have come under my consideration. 

 Lastly, the oxygenated derivative of the bromide resembles so per- 

 fectly the monammonium- and the monophosphonium-bases, that 

 more than once during my experiments I was inclined to doubt the 

 correctness of my interpretation. 



There is no direct proof of the diatomic character of the com- 

 pound. Why should we reject the simple formula deducible from 

 experiment ? The hydrocarbons C n H n are very prone to molecular 

 transformations without change of composition. The idea suggested 

 itself, that the diatomic saline molecule might be split into two 

 monatomic saline molecules, 



[(C. H 5 ) 6 (C 4 H 4 ) P.] Br 2 =2 ([(C.H.), (C 2 H 2 )' P] Br). 



* Proceedings, vol. ix. pp.285 and 631. 



