52 



SECTIONAL ADDRESSES 



Au — C=N -> Au group of atoms and the positions of the propyl groups 

 are shown to be : 



pj-a 



I 



— C=N ^ Au - Pr" 



I 

 C 



III 



N 



The projections on (loo) and (oio) are non-centrosymmetric, but 

 owing to the overwhelming influence of the gold atoms, whose c co- 

 ordinates can be estimated, the arbitrary phase constants corresponding 

 to the F(Oki)'s and F(boi)'s can be calculated for the completion of the 

 projection on (oio) and (loo). The three projections so obtained give 

 the coordinates of all the gold atoms and indicate approximately the 

 positions of the carbon and nitrogen atoms. Consideration of these 

 projections and of the space available permit the assignment of coordinates 

 to all atoms. Between atoms in different molecules there is no approach 

 less than the usual 3 • 6 A. The Fourier analysis shows clearly the general 

 positions of the 7z-propyl groups and the ' square ' character of the gold 

 valencies, but it must be understood that the details concerning the 

 terminal parts of the w-propyl groups is only suggested to be as indicated, 

 alternatively tilted above and below the plane of the square, in order to 

 leave sufficient space between molecules (Fig. 4). The shape of the 

 molecule approximates to a real square and the distance, Au — C=N->Au, 

 is the same for each side and equal to 5 • 18 A, thus confirming the suggested 

 formulation, Au — C=N -> Au, which, from available data on bond 

 lengths, should require 5 • 28 A. 



{e) Among the studies of gold derivatives of organic sulphur com- 

 pounds being carried out in my laboratory, I will only refer to one which 

 presents certain unusual features. My collaborators and I have studied 

 the reactions which may be briefly outlined, thus : 



(Bz2SAuBr,)2 

 IV 



Bz^S 



bromine 



-> BzgS -> Au 

 II 



(Bz2SAuBrI)2 

 III 



Analogous substances have been previously prepared by different 

 authors. Substance (IV), for example, was described by McPhail 



