Reversible Transformation between Alkylidene, Alkylidyne, and Vinylidene Ligands in High-Valent Bis(phenolate) Tungsten Complexes

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• 作者：Haruka Nishiyama ; Keishi Yamamoto ; Andreas Sauer ; Hideaki Ikeda ; Thomas P. Spaniol ; Hayato Tsurugi ; Kazushi Mashima ; Jun Okuda
• 刊名：Organometallics
• 出版年：2016
• 出版时间：April 11, 2016
• 年：2016
• 卷：35
• 期：7
• 页码：932-935
• 全文大小：351K
• 年卷期：0
• ISSN：1520-6041

文摘

A tungsten alkylidyne complex [{(OC₆H₂^tBu₂-4,6)₂(SCH₂CH₂S)}W(≡CEt)X] (X = O^tBu, 1a) with a bridged bis(phenolate) ligand was prepared from the alkoxy precursor (^tBuO)₃W≡CEt and the corresponding bis(phenol). The tert-butoxy ligand in 1a was substituted against chloride or trimethylsilylmethyl to give 1b (X = Cl) or 1c (X = CH₂SiMe₃). X-ray diffraction studies of 1a and 1c showed an octahedral cis α-configuration of the metal atom. Hydride abstraction from the β-position of the n-propylidyne ligand in 1a and 1c with [Ph₃C][B(C₆F₅)₄] gave high-valent cationic vinylidene complexes [{(OC₆H₂^tBu₂-4,6)₂(SCH₂CH₂S)}W(═C═CHMe)X][B(C₆F₅)₄] (2a: X = O^tBu; 2c: X = CH₂SiMe₃), while protonation of 1a with [PhNMe₂H][B(C₆F₅)₄] gave the cationic n-propylidene complex [{(OC₆H₂^tBu₂-4,6)₂(SCH₂CH₂S)}W(═CHEt)(O^tBu)][B(C₆F₅)₄] (3a). The alkylidyne complex 1a was regenerated from the alkylidene 3a by deprotonation with Ph₃P═CH₂, whereas 1c was regenerated from 2c by nucleophilic attack by a hydride at the β-carbon of the vinylidene moiety. The cationic tungsten alkylidyne complex [{(OC₆H₂^tBu₂-4,6)₂(SCH₂CH₂S)}W(≡CEt)(PhNMe₂)][B(C₆F₅)₄] (4c) was obtained from [{(OC₆H₂^tBu₂-4,6)₂(SCH₂CH₂S)}W(═CHEt)(CH₂SiMe₃)][B(C₆F₅)₄] (3c) in chlorobenzene at 60 °C.