The compound [(CH,)* N] zS (mp 20, bp est. 127") holds 2BF3 firmly in vacuo at 165', while [(CH~) ZN]~ SO(mp 31", bp est. 209") forms a less stable 1.5 BFa adduct for Rhich loglo Pdiaa.(mm.)= 4.143-1274/T, and [(CHs) zN]* SOz (known mp 73", bp est. 225') holds only one BF3, still more weakly. It is argued that the main reason for such a trend of decreasing BF3-bonding power is the inductive effect of 0 in increasing the S-4 7-bonding, rendering ...