Small-Molecule Activation within the Group 6 Complexes (η5-C5Me5)[N(iPr)C(Me)N(iPr)]M(CO)(L) for M = Mo, W and L = N2, NCMe, η2-Alkene, SMe2, C3H6O

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• 作者：Wesley S. Farrell ; Brendan L. Yonke ; Jonathan P. Reeds ; Peter Y. Zavalij ; Lawrence R. Sita
• 刊名：Organometallics
• 出版年：2016
• 出版时间：April 25, 2016
• 年：2016
• 卷：35
• 期：8
• 页码：1132-1140
• 全文大小：632K
• 年卷期：0
• ISSN：1520-6041

文摘

A series of midvalent monocyclopentadienyl monoamidinate (CPAM) group 6 complexes of the general formula Cp*[N(p>ip>Pr)C(Me)N(p>ip>Pr)]M(CO)(L) (II), where Cp* = ηp>5p>-C₅Me₅ and M = Mo, W, have been prepared, and most of them have been structurally characterized. Treatment of the ditungsten “end-on-bridged” dinitrogen complex {Cp*[N(p>ip>Pr)C(Me)N(p>ip>Pr)]W}₂(μ-ηp>1p>:ηp>1p>-N₂) (3) with excess NCMe under a CO atmosphere produced the ditungsten bridging diimido complex {Cp*[N(p>ip>Pr)C(Me)N(p>ip>Pr)]W}₂[μ-ηp>1p>:ηp>1p>-NC(Me)═C(Me)N] (4). Photolysis of Cp*[N(p>ip>Pr)C(Me)N(p>ip>Pr)]M(CO)₂, where M = Mo (6), W (7), or treatment of Cp*[N(p>ip>Pr)C(Me)N(p>ip>Pr)]Mo(CO)(NCMe) (1a) with excess alkene provided Cp*[N(p>ip>Pr)C(Me)N(p>ip>Pr)]M(CO)(L) for M = Mo and L = ηp>2p>-ethene (8), M = W and L = ηp>2p>-ethene (9), M = Mo and L = ηp>2p>-norbornene (10), M = W and L = ηp>2p>-norbornene (11), M = W and L = ηp>2p>-cyclopentene (12), M = Mo and L = ηp>2p>-cyclopentene (13), and M = Mo and L = ηp>2p>-styrene (14). When isobutene was employed as the alkene, C–H bond activation occurred to produce Cp*[N(p>ip>Pr)C(Me)N(p>ip>Pr)]W(H)(ηp>3p>-C₄H₇) (15). Photolysis of 7 in the presence of SMe₂ provided Cp*[N(p>ip>Pr)C(Me)N(p>ip>Pr)]W[κ-C,O-C(O)Me](SMe) (16) through oxidative C–S bond activation of a coordinated SMe₂, followed by 1,1-carbonyl migratory insertion into the new W–C bond. Finally, reaction of 1a with propylene oxide (C₃H₆O) provided the 16-electron complex Cp*[N(p>ip>Pr)C(Me)N(p>ip>Pr)]Mo[C(O)CH(Me)CH₂O] (19) via similar oxidative C–O bond activation of coordinated C₃H₆O, followed by 1,1-carbonyl migratory insertion into the Mo–C bond of an intermediate metallaoxetane. Under a CO atmosphere, 19 is converted to the 18-electron complex Cp*[N(p>ip>Pr)C(Me)N(p>ip>Pr)]Mo[C(O)CH(Me)CH₂O](CO) (20). These results provide additional support for the development of new stoichiometric and catalytic transformations that are mediated by CPAM group 6 metal complexes and that are relevant to the goal of small-molecule fixation.