AN INFRARED AND P-31 MAGIC-ANGLE-SPINNING NUCLEAR-MAGNETIC-RESONANCE STUDY OF THE ADSORPTION OF PCL3 AND OPCL3 ON SILICA

Phosphorus trichloride initially physically adsorbs on silica at room temperature via an interaction with surface silanol groups. Following prolonged contact over several hours,it dissociates to yield the chemi sorbed SiOP-containing species SiOPCl2, SiOP=O(H,OH), and(SiO)2P=O(H). The last two of these species can also be produced by impregnation of silica with phosphorous acid, H3PO3, from aqueous solution. Phosphory l chloride, O=PCl3, also physically adsorbs on silanols, but the inter action is stronger than that which occurs with PCl3, and no further re action occurs at room temperature. Some anomalies previously reported in the literature from earlier studies of PCl3 adsorption on silica ha ve been shown to be due to OPCl3 which can be present as a very low le vel (1-2 %) impurity in commerially available PCl3.