Nonclassical Ions with Hydrogen Bridged

The secondary cyclodecyl ion 167 was generated from 1-chlorocyclodecane in SbF,—SOjFCl—SOjF at —140 °C at —120 °C this ion decomposes to liberate hydrogen and form a decalyl ion 168  

More thermally stable are ditertiary analogues — 1,5- and 1,6-dimethylcyclodecyl cations Of late have also been d aibed ions with a p-hydrido bridge between the secondary and the tertiary carbons 

The dioice between one symmetrical structure of ion 167 or rapid equilibration of cyclodecyl ion in favour of the former is made from the following data  

1) the constant J( C— H) between the bridged hydrogen and the neighbouring carbons (32 5 cps) the value of the above constant for the equilibrium should be -65cps[(130 -H 0)/2]  

2) the unusual high-field chemical shift of the hydrogen signal [—6.85 ppm ( ) for the secondary ion 167] in the H NMR spectrum for equilibrium this signal should be expected at 1.5 ppm  

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