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 1 underwent nucleophilic addition reactions toward 2, 6-Me₂C₆H₃NC and PhCH₂CN, respectively yielding monoinsertion products L₂Y₂[μ-η¹:η³:η³-HCC(2,6-Me₂C₆H₃)N](AlMe₃)(μ₂-Me) (L = (PhCH₂)₂NC(NC₆H₃iPr₂-2,6)₂) (2) and L₂Y₂[μ-η¹:η³:η³-HCC-(CH₂Ph)N](AlMe₃)(μ₂-Me) (3). Additionally, complex 1 was treated with iPrN═C═NiPr (DIC) (5 equiv), obtaining a yttrium complex LY[(AlMe₂)(NiPr₂)₂CCHC(NiPr₂)₂(AlMe₂)][(NiPr₂)₂CMe] (4) featuring an Al-heterocyclic six-membered ring structure and a mixed guanidinate/amidinate yttrium complex LY[(NiPr₂)₂CMe]₂ (5). Complex 1 reacted with CS₂ (2 equiv), leading to the formation of the binuclear yttrium disulfides L₂Y₂(μ₂-S)(μ₂-η¹:η²-S₂)(AlMe₃)₂ (6) through the cleavage of both C═S bonds in CS₂. Furthermore, a mixed μ₄-CH/μ₂-C≡CSiMe₃ yttrium complex [LY(AlMe₃)]₂(μ₂-C≡CSiMe₃)(μ₄-CH) (9) was synthesized through the protonolysis of Me₃SiC≡CH (1 equiv) with complex 1. Interestingly, the bimetallic alkynyl-bridged yttrium complex [LY(μ-C≡CSiMe₃)]₂(μ-(Z)-Me₃SiC═C═C═CSiMe₃) (10) was isolated when the Me₃SiC≡CH (4 equiv) was treated with complex 1. Notably, in the presence of PhSSPh, complex 1 exhibited distinctive reactivity to CO, undergoing a CO deoxygenative coupling reaction that ultimately yielded a yttrium oxo complex L₂Y₂(μ₃-O)(AlMe₃)(μ₂-SPh)(μ₂-C≡CMe) (12), and the mixed μ₄-CH/μ₂-SPh yttrium complex L₂Y₂(μ₄-CH)(μ₂-SPh)(AlMe₃)₂ (11) was identified as a key intermediate in this transformation.