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Beyond Takai's Olefination Reagent: Persistent Dehalogenation Emerges in a Chromium(III)-μ₃ -Methylidyne Complex.

ABSTRACT: Reaction of CHI₃ with six equivalents of CrCl₂ in THF at low temperatures affords [Cr₃ Cl₃ (μ₂ -Cl)₃ (μ₃ -CH)(thf)₆ ] as the first isolable high-yield Cr^III μ₃ -methylidyne complex. Substitution of the terminal chlorido ligands via salt metathesis with alkali-metal cyclopentadienides generates isostructural half-sandwich chromium(III)-μ₃ -methylidynes [Cp^R ₃ Cr₃ (μ₂ -Cl)₃ (μ₃ -CH)] (Cp^R =C₅ H₅ , C₅ Me₅ , C₅ H₄ SiMe₃ ). Side and decomposition products of the Cl/Cp^R exchange reactions were identified and structurally characterized for [Cr₄ (μ₂ -Cl)₄ (μ₂ -I)₂ (μ₄ -O)(thf)₄ ] and [(η⁵ -C₅ H₄ SiMe₃ )CrCl(μ₂ -Cl)₂ Li(thf)₂ ]. The Cl/Cp^R exchange drastically changed the ambient-temperature effective magnetic moment μ_eff from 9.30/9.11 μ_B (solution/solid) to 3.63/4.32 μ_B (Cp^R =C₅ Me₅ ). Reactions of [Cr₃ Cl₃ (μ₂ -Cl)₃ (μ₃ -CH)(thf)₆ ] with aldehydes and ketones produce intricate mixtures of species through oxy/methylidyne exchange, which were partially identified as radical recombination products through GC/MS analysis and ¹ H NMR spectroscopy.

SUBMITTER: Trzmiel S

PROVIDER: S-EPMC8456800 | biostudies-literature |

REPOSITORIES: biostudies-literature

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