48 



SECTIONAL ADDRESSES 



These compounds yield with ethylenediamine colourless crystalline 

 non-electrolytes of type II — monoethylenediaminotetraalkyldicyano- 

 digold— analogous to the above described monoethylenediaminotetra-«- 

 propyldibromodigold, the molecules of which unlike those of the parent 

 substances contain only two atoms of 4-covalent auric gold. In this series, 

 It has so far been found impossible to isolate compounds of type III which 

 would be analogous to the corresponding bromides. One particularly 

 mterestmg feature of compounds of types I and II is the mode of their 

 decomposition to give finally monocyanogold (aurous cyanide). Com- 

 pounds of type I are converted into compounds of type IV on standing 

 at the ordmary temperature and the ethyl compound undergoes this 

 change explosively on mere rubbing ; at their melting points the change 

 takes place very rapidly in all cases. These decompositions which have 

 been quantitatively investigated are illustrated : 



R 



R 



R— Au— C=N-^ Au— R 



i ' 



N C 



III II — mR' + 



C N 



I I 



R— Au <-N=C— Au— R 



L i 



I 



CN CN 



I I 



R— Au^NHa.CgH^.HaN^Au— R - 



i L 



II 



R 



I 

 R— Au— C=N-^Au 



I I 



N C 



I I 



Au ^N=C— Au— R 



R 



IV 



-R 



-2R' + 



\ ^ 



NH^- 



^4R' + 



Au— C=N-# 



t 



N 



III 

 C 



I 

 Au^N=C- 



^Ai 



I 

 C 



III 



N 



-Ai 



Au C2H4 



R 



NH 



2 — » 



V 



Au(CN)2 



VI 



The dialkyldicyanodigold compounds (IV) are non-electrolytes like 

 the dialkylmonocyano-gold compounds (I), but unlike the latter they are 

 very sparingly soluble in organic solvents and they decompose without 

 melting. They constitute further examples of mixed 4-covalent auric 

 and 2-covalent aurous compounds. The decompositions I -» IV -^ V 

 afford chemical evidence regarding the constitution of monocyanogold 

 (gold monocyanide, aurous cyanide), indicating that it is a non-electrolyte." 

 that It IS a 2-covalent aurous compound and that there are four such gold 

 atoms in the molecule which like that of a compound of type (I) is planar 

 Pure gold monocyanide prepared in such a way should be suitable for 

 A-ray crystallographic investigation. The ethylenediaminodialkylgold 



