3i8 SECTIONAL TRANSACTIONS.— B. 



Mr. T. W. J. Taylor and Mr. L. E. Sutton. — The configurations of 

 the oximes from measurement of electric di-pole moment. 



The configurations of the oximes have been established by the measure- 

 ment of the electric moments of certain of their derivatives. For the 

 ketoximes this can be done absolutely from the moments of their N-methyl 

 ethers. In the case of the aldoximes this method cannot be applied, because 

 one and the same N ether is obtained on methylating either of the two 

 isomeric oximes. The two O-methyl ethers of p-nitrobenzaldoxime, how- 

 ever, are known, and their relation to their parent oximes is unambiguous. 

 By comparing their moments with those of the O-ethers of the closely related 

 p-nitrobenzophenoneoximes, whose configurations are known from the 

 above argument, the configurations of the aldoximes themselves are 

 established. The results show clearly that the modern view as to the con- 

 figurations of the aldoximes is correct — i.e. that in the reaction used for 

 obtaining configuration, the action of Na2C03 on the acetyl compounds, the 

 loss of acetic acid in the P series involves groups anti to one another, and 

 that the original configurations of Hantzsch and Werner must be reversed. 



Since it was found previously that the one N-methyl ether of p-nitro- 

 benzaldoxime has a moment 6-4X10^', it appears that the N ethers of 

 aldoximes have the (3 configuration, as has been suspected. 



Dr. N. V. SiDGWiCK, F.R.S. — Molecular di-pole moments and inter- 

 valency angles. 



The di-pole moment of a molecule is the vector sum of those of its con- 

 stituent links ; hence if these moments are known, the valency angles can 

 be calculated. 



Qualitatively it follows that a molecule AB3 if polar (NH3, PCI3) is 

 pyramidal : if non-polar (BCI3) is plane, with angles of 120°. ABg, if 

 non-polar (COo, CS2, NjO), is rectilinear ; if polar (HgO, HjS, SOg) is bent. 



Quantitatively, by comparing the moment of, say, diphenyl ether with 

 that of its para-di-substitution product, e.g. (Cl-CgH4)20, we can determine 

 the angle between the oxygen valencies (Smyth, Bergmann, Hassel, Sutton). 

 The mutual — electromeric and inductive — effects of the moments can be 

 eliminated by using substituents of different types. 



The conclusions so far reached are : 



(i) With valency groups of less than eight electrons, two valencies are ap- 

 proximately at 180° (mercury diphenyl), and three in a plane at 120° (BCI3). 



(2) With a complete octet the tetrahedral arrangement holds. The 

 angles found are approximately: of the C-C valencies 110° in diphenyl 

 methane, 130° in benzophenone ; of the C-O and C-S valencies in diphenyl 

 ether and thioether about 140°. This is in striking opposition to Pauling's 

 theory, which requires smaller angles (about 90^) for oxygen and sulphur. 



Dr. F. G. Mann. — Chemical evidence on the configuration of the 

 4-co-valent compounds of the metals of the platinum group. 



Werner's work on the stereochemistry of complex metallic salts was 

 directed chiefly towards the salts of metals showing a co-ordination number 

 of 6, and the configuration of such compounds is now beyond reasonable 

 doubt. Recent work has therefore concentrated more particularly on the 

 stereochemistry of complex salts of metals showing a co-ordination number 

 of 4. 



