Quantum Calculation on the Reduced Systems

The micro-computer-assisted approach we have developed shows that the 6-dimen-sional E = f(a, P, y, 8, e) conformational problem within the set of SOAz geometries can be actually reduced to a monodimensional one. In other words, the passage from SOAz(I) to SOAz(II B) can be then simulated upon rotation of the Az group linked to the sulphur, the four other wings staying unchanged, in first approximation at least. 

Consequently, such a reduced problem became amenable again to a common treatment by quantum mechanics, more especially as all the exocyclic N atoms keep exactly the same tetrahedral character whatever the molecule they belong to (Fig. 66). 

When starting from the X-ray structure of SOAz(I), we computed the total energy upon the rotation through 360° of the Az group linked to S around the S—Nexo bond (Fig. 65) within CNDO approximation. This figure calls for the following remarks. 

Incidentally, the gaps of energy within the (SOAz(IIA)/pseudo-SOAz(IIA)) and (SOAz(IIB)/pseudo-SOAz(IIB)) pairs appear quite identical, i.e. 11.68 and 11.72 kcal mole respectively  

SOAz(II A) being the most natural form of SOAz (as MYKO-XYL is within the MYKO structures series). 

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