Synthesis of an N‐Heterocylic Boryl‐Stabilized Disilyne and its Application to the Activation of Dihydrogen and C−H Bonds

The synthesis of low-valent silicon compounds that enable the activation of small molecules has been of great current interest. Reduction of N-heterocyclic boryltribromosilane (NHB)SiBr 3 ( 2 , NHB = [ArN(CMe) 2 NAr]B, Ar = 2,6- i Pr 2 C 6 H 3 ) with three equiv. of lithium in diethyl ether yielded the NHB-stabilized disilyne (NHB)Si≡Si(NHB) ( 3 ). Disilyne 3 slowly reacted with toluene, leading to the activation of one benzylic C−H bond and one C=C double bond with the formation of 4 . Treatment of 3 with dihydrogen under 1 atm at room temperature led to the exclusive formation of the first boryl-stabilized 1,2-dihydrodisilene. Compounds 3 - 5 have been characterized by single-crystal X-ray diffraction analysis, which indicated the co-planarity of the B−Si−Si−B plane with the NHB rings in compounds 3 and 5 . DFT calculations indicated the significant π electron delocalization of the Si−Si multiple bonds to the B−N bonds in NHB rings.