Simple Adsorption at Basic Sites

Simple Adsorption at Basic Sites A Lewis acid might absorb at (cus), for example, carbon dioxide. 

It may be noted that Cr3+ is a hard acid and 0 is a hard base (35). Therefore, one expects water and ammonia, which are hard bases, to adsorb at Cr3+ more strongly than carbon monoxide or ethylene, which are soft. The strength of bonding of ethylene and carbon monoxide should be augmented upon reduction of Cr3+ to the softer Cr2+ (35, 39). No molecular compounds are known in which Cr(Ill) is bonded to either carbon monoxide or ethylene. Clearly, surface coordinative un-saturation provides an ideal opportunity to observe the formation of 

---