Crystalline Silylene-Stabilized\nDiboryne and Siladiborirene

The exploration of main group compounds with multiple\nbonds has\nsignificantly enhanced our understanding of chemical bonding and expanded\ntransition-metal-free bond activation and catalysis. Diborynes, characterized\nby a boron–boron triple bond (BB), represent a particularly\nchallenging area due to boron’s limited valence electrons.\nHere, we report the synthesis and characterization of a silylene-stabilized\ndiboryne (<b>7</b>), expanding the frontier of diboryne stabilization.\nX-ray diffraction analysis and density functional theory calculations\nconfirm the presence of a BB bond in the diboryne. Remarkably,\nthis diboryne undergoes [1 + 2] cycloaddition reactions with dichlorosilylene\nand terphenyl isocyanide, producing unprecedented siladiborirene <b>(8)</b> and diborirenimine (<b>9</b>), respectively. X-ray\ndiffraction studies show that <b>8</b> and <b>9</b> bear\na three-membered boron-containing heterocycle with a BB bond,\nand computational studies reveal their distinct aromatic character.