50 5b of equilibrium was tentatively excluded on the basis that the spectrum showed no change at-80 OC (CD2C12). In the previous paper, we showed that 2 J p~~ depends strongly on the OPCH dihedral angle. 7 Protons trans to P= O couple more strongly with phosphorus than the gauche protons. For example, in dineopentylphenylphosphine oxide, in which the neopentyl groups are fixed in the trans position because of the steric ...
