Bis(pyridylimino)isoindolato (BPI) Osmium Complexes: Structural Chemistry and Reactivity

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• 作者：Astrid L. M眉ller ; Hubert Wadepohl ; Lutz H. Gade
• 刊名：Organometallics
• 出版年：2015
• 出版时间：June 22, 2015
• 年：2015
• 卷：34
• 期：12
• 页码：2810-2818
• 全文大小：535K
• ISSN：1520-6041

文摘

A series of osmium complexes with monoanionic, meridionally coordinating 1,3-bis(2-pyridylimino)isoindolates (BPI) as spectator ligands has been synthesized. Reaction of the dichlorido metal precursor [OsCl₂(PPh₃)₃] with the lithiated BPI ligand transfer reagent gave the chlorido complex [(tBu-BPI^Me)Os(PPh₃)₂Cl] (2) which, in turn, was reacted with lithium triethylborohydride to yield the hydrido complex [(tBu-BPI^Me)Os(PPh₃)₂H] (3). Treatment of complex 2 with thallium hexafluorophosphate under a nitrogen pressure afforded the cationic dinitrogen complex [(tBu-BPI^Me)Os(PPh₃)₂(N₂)]PF₆ (4), which contains an end-on coordinated dinitrogen molecule trans to the isoindolato nitrogen atom. To synthesize the alkynyl complex [(tBu-BPI^Me)Os(PPh₃)₂(C鈮Ph)] (5), the chlorido complex 2 was treated with lithium phenylacetylide. Complex 5 was subsequently converted quantitatively by addition of one or two equivalents of HBF₄ to the vinylidene complex [(tBu-BPI^Me)Os(PPh₃)₂(鈺怌鈺怌HPh)]BF₄ (6), and the cationic species [(H-tBu-BPI^Me)Os(PPh₃)₂(鈺怌鈺怌HPh)](BF₄)₂ (7), respectively; the latter being formed via protonation of one imine nitrogen atom of the BPI ligand. Upon stirring, a toluene solution of the chlorido complex 2 with benzyl potassium, the four-membered metallacycle [(tBu-BPI^Me)Os(PPh₃)(o-C₆H₄PPh₂)] (8) was obtained, which reacted with molecular hydrogen and phenyl acetylene to give the hydrido complex 3 and the acetylide complex 5, respectively. Stirring of 8 with methyl acetylenedicarboxylate (DMAD) yielded [(tBu-BPI^Me)Os(DMAD)(o-C₆H₄PPh₂)] (9), while treatment with carbon monoxide gave the acyl complex [(tBu-BPI^Me)Os(o鈥揅(O)-C₆H₄PPh₂)(CO)] (10) by an insertion of CO into the osmium carbon bond.