B— CHEMISTRY 



43 



standing at the ordinary temperature, its solutions in chloroform or 

 benzene slowly become cloudy due to the following change : 



Br 



Br 



2 Pr« — Au ^ 



I 

 Pr« 



en 



Au — Pr" 



rPr" NH2 



Au C2H4 Br + 



Pr" _Pr'' NH.^ _ 



Pj.a Br Pr" 



\ X ^ / 

 Au Au 



/ \ / \ 

 Pr« Br Pr» 



The salt, ethylenediaminodi-n-propylgold bromide, is insoluble in such 

 solvents as chloroform and benzene. By repeatedly washing the com- 

 pound with water the above change goes to completion from left to right, 

 the di-«-propylmonobromogold being insoluble in water. The de- 

 composition of the monoethylenetetraalkyldicyanodigold compounds 

 follows a different course (see below). On being heated to its melting 

 point, monoetliylenediaminotetra-«-propyldibromodigold undergoes the 

 following change : 



Br Br 



Pr" — Au 

 Pr» 



NH2— C2H4— H^N 



Br 



• Au — Pr"" 

 Pr« 



= Pr«— Au <- NHo— CoH,— HoN -^ Au— Br + 2 Pr-^' 



Pr" 



(CeHi^) 



The solid product of the reaction is monoethylenediaminodi-«-propyl- 

 dibromodigold and this reaction indicated that suitable organic gold 

 compounds may be the potential source of free radicals (see below) and 

 that it is possible to prepare mixed auric-aurous compounds containing 

 4-covalent auric gold and 2-covalent aurous gold in the same molecule. 

 While the analogous ethyl compound has not been prepared. Dr. F. H. 

 Brain and I (1938) have recently prepared the following compounds : 



Br 



Et— Au 



Et 

 mono-Pf 

 Br 



NH2— CH2— CH2— O— CH2— CH2— H2N 



Br 



I 

 >Au— Et 



I 

 Et 



-diaminodiethylethertetraethyldibromodigold, m.p. 87°, 



Br 



Et— Au - 



NHg— CH2— CH2— NEt, -> Au— Et 



Et 



Et 



mono-asym.-N-diethylethylenediaminotetraethyldibromodigold, m.p. 84" 



