Abstract Stepwise replacement of O in 1, 3-dioxa-2-phospha (V)-cyclohexanes (or related ring systems) by NR (R= H or Me) leads to an increase in the stability of the hetero-ring ions produced under electron impact conditions. In the case of the 2-phenoxy derivatives, there is also an increased abundance of [M [BOND] PhO]+ or [M [BOND] PhOH]+ ions, and, for the 2- sulphides, a reduction in the abundance of [MS]+ and [M-SH]+ ions, with a concurrent ...
