The Reactivity Studies on the Binuclear Heterobimetallic Y/Al “Methylidyne” Complex

The low activity of metal bridging carbynes has been widely known. Herein, a binuclear heterobimetallic Y/Al "methylidyne" complex <b>1</b> underwent nucleophilic addition reactions toward 2, 6-Me₂C₆H₃NC and PhCH₂CN, respectively yielding monoinsertion products <b>L</b>₂Y₂[μ-η¹:η³:η³-HCC(2,6-Me₂C₆H₃)N](AlMe₃)(μ₂-Me) (<b>L</b> = (PhCH₂)₂NC(NC₆H₃^<i>i</i>Pr₂-2,6)₂) (<b>2</b>) and <b>L</b>₂Y₂[μ-η¹:η³:η³-HCC-(CH₂Ph)N](AlMe₃)(μ₂-Me) (<b>3</b>). Additionally, complex <b>1</b> was treated with ^<i>i</i>PrN═C═N^<i>i</i>Pr (DIC) (5 equiv), obtaining a yttrium complex <b>L</b>Y[(AlMe₂)(N^<i>i</i>Pr₂)₂CCHC(N^<i>i</i>Pr₂)₂(AlMe₂)][(N^<i>i</i>Pr₂)₂CMe] (<b>4</b>) featuring an Al-heterocyclic six-membered ring structure and a mixed guanidinate/amidinate yttrium complex <b>L</b>Y[(N^<i>i</i>Pr₂)₂CMe]₂ (<b>5</b>). Complex <b>1</b> reacted with CS₂ (2 equiv), leading to the formation of the binuclear yttrium disulfides <b>L</b>₂Y₂(μ₂-S)(μ₂-η¹:η²-S₂)(AlMe₃)₂ (<b>6</b>) through the cleavage of both C═S bonds in CS₂. Furthermore, a mixed μ₄-CH/μ₂-C≡CSiMe₃ yttrium complex [<b>L</b>Y(AlMe₃)]₂(μ₂-C≡CSiMe₃)(μ₄-CH) (<b>9</b>) was synthesized through the protonolysis of Me₃SiC≡CH (1 equiv) with complex <b>1</b>. Interestingly, the bimetallic alkynyl-bridged yttrium complex [<b>L</b>Y(μ-C≡CSiMe₃)]₂(μ-(<i>Z</i>)-Me₃SiC═C═C═CSiMe₃) (<b>10</b>) was isolated when the Me₃SiC≡CH (4 equiv) was treated with complex <b>1</b>. Notably, in the presence of PhSSPh, complex <b>1</b> exhibited distinctive reactivity to CO, undergoing a CO deoxygenative coupling reaction that ultimately yielded a yttrium oxo complex <b>L</b>₂Y₂(μ₃-O)(AlMe₃)(μ₂-SPh)(μ₂-C≡CMe) (<b>12</b>), and the mixed μ₄-CH/μ₂-SPh yttrium complex <b>L</b>₂Y₂(μ₄-CH)(μ₂-SPh)(AlMe₃)₂ (<b>11</b>) was identified as a key intermediate in this transformation.