Results The carbon chemical shifts (Tables I-VIII) are most easily assigned in the symmetrical 2, 2, 3, 4, 4-pentamethylphosphetanes in Table I. The large 13C-31P coupling and high shift (low shielding), as well as the twofold intensity, allow C-2 and C-4 to be identified. The high shift of C-3 is characterktic of a tertiary carbon. C-7 gives a shift normal for a free methyl bound to a carbon atom and has unit intensity. The remaining two ...
