Trapping small molecules capacity

Molecular sieves have pores or channels in their structures. A small molecule such as water can diffuse into these channels and become trapped. The sieves are excellent drying agents, have a high capacity, and dry liquids completely. The disadvantages are that they dry slowly and are more expensive than the more common drying agents. 

Since the donor strength of duroquinone is rather small, the capacity of the nickel atom in stabilizing two duroquinone molecules by dative n bonding is probably limited. The situation is similar to that in the nickel complexes of the 1,1-dicyano- and 1,1,2-tricyanoethylenes which also form only 1 1 complexes (Section IV, B, 3). During thermal decomposition of (XX) monomeric, coordinately unsaturated Ni(duroquinone) is formed. This species is evidently very reactive and rapidly associates to (XXI). It may be trapped in the monomeric state if generated in the presence of electron donors such as cyclic dienes and some phosphines. Under these conditions new complexes of composition olefin-Ni(0)-duroquinone and (phosphine)2-Ni(0)-duroquinone are formed (55, 56, 57). 

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