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In spite of the explosion in supramolecular chemistry in recent years, few examples of boron host compounds ['] have emerged in the literature, presumably because of the air sensitivity of many of the boron-containing functionalities. In this regard, boronic acid derivativesL2] have found favor because of their relative air stability. To our knowledge the only host compound with borate units known to date has been reported by Nassiinbeni et a1.[31 They showed that certain tetraalkylammonium tetraalkylborates form liquid clathrates with a variety of hydrocarbons. However, the borate derivatives were difficult to purify and no satisfactory X-ray analysis could be obtained. Here we report on the synthesis of the first air-and water-stable cy;~ noborate [~~ clathrand 1 which forms both a liquid and solid clathrate with furan depending on water content. An X-ray analysis [51 of the solid clathrate of 1 with furan has revealed an …