New Adamantane-like Silicophosphate Cage and Its Reactivity toward Tris(pentafluorophenyl)borane

The condensation reaction between Ph₂Si(OC(O)CH₃)₂ and OP(OSiMe₃)₃ leads to elimination of CH₃C(O)OSiMe₃ and the formation of the new silicophosphate cage molecule Ph₁₂Si₆P₄O₁₆ (1) with an adamantane-like core possessing four terminal P═O moieties and six O-SiPh₂-O bridging groups. Compound 1 was further reacted with the Lewis acid B(C₆F₅)₃. We observed adduct formation by coordination through the P═O→B bonds and isolated and structurally characterized two new molecules. In the first of them, the adamantane-like cage is preserved and three phosphoryl oxygen atoms coordinate to boranes, forming Ph₁₂Si₆O₁₆P₄·3B(C₆F₅)₃ (2); the remaining P═O group is inverted toward the cage center pointing along a C₃ molecular axis. The molecule is chiral, and the compound 2 crystallizes as a conglomerate of homochiral crystals. Enantiomers 2M and 2P were both structurally characterized. The second adduct resulted from an unexpected reorganization of the Si-O-P linkages in the adamantane cage during the reaction of 1 with 4 equiv of B(C₆F₅)₃. The bis-adduct Ph₆Si₃O₈P₂·2B(C₆F₅)₃ (3) was formed with an inorganic core representing half of the parent molecule 1.