Closing the Gap: Preparation and Characterization of the First Half-Open and Open Manganocene Complexes

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• 作者：Matthias Reiners ; Dirk Baabe ; Matthias Freytag ; Peter G. Jones ; Marc D. Walter
• 刊名：Organometallics
• 出版年：2016
• 出版时间：June 13, 2016
• 年：2016
• 卷：35
• 期：11
• 页码：1986-1994
• 全文大小：482K
• 年卷期：0
• ISSN：1520-6041

文摘

The first preparations of half-open and open manganocenes were accomplished. Treatment of KPdl′ (Pdl′ = 2,4-(Me₃C)₂C₅H₅)) with [{(η⁵-Cp”)Mn(thf)(μ-I)}₂] (Cp″ = 1,2,4-(Me₃C)₃C₅H₂) and MnI₂(thf)₂ resulted in the formation of [(η⁵-Cp″)Mn(Pdl′)] (2) and [(Pdl′)₂Mn] (4), respectively. Both compounds adopt a high-spin (S = 5/2) ground state. Maximum spin states are rather unusual for pentadienyl complexes, since these ligands generally stabilize transition metal complexes in their low-spin state. In addition, the electronic structure of 2 was compared to its closed analogue [(η⁵-Cp″)Mn(η⁵-Cp′)] (Cp′ = 1,3-(Me₃C)₂C₅H₃), which also adopts the high-spin configuration because of steric hindrance destabilizing the electronically more favorable low-spin state. Reaction of KPdl′ with [(C₅H₅)₂Mn] yields the trimetallic compound [{(η⁵-Pdl′)Mn(η⁵-C₅H₅)]}₂Mn] (5) concomitant with the formation of 2,4,7,9-tetra-tert-butyl-1,3,7,9-decatetraene (Pdl′₂), indicating reduction of two Mn atoms. Solid-state magnetic susceptibility studies and density functional theory computations suggest that the electronic structure in 5 is best described as two diamagnetic (S = 0) [(η⁵-Pdl′)Mn(η⁵-C₅H₅)]⁻ Mn(I) anions, each being coordinated to a central Mn(II) cation with a high-spin (S = 5/2) configuration.