Preparation, Structural Analysis, and Reactivity Studies of Phosphenium Dications

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• 作者：Madelyn Qin Yi Tay ; Gordana Ilić ; Ulrike Werner-Zwanziger ; Yunpeng Lu ; Rakesh Ganguly ; Louis Ricard ; Gilles Frison ; Duncan Carmichael ; Dragoslav Vidović
• 刊名：Organometallics
• 出版年：2016
• 出版时间：February 22, 2016
• 年：2016
• 卷：35
• 期：4
• 页码：439-449
• 全文大小：584K
• ISSN：1520-6041

文摘

This work expands on the recent synthesis and reactivity of the two-coordinate P(III)-containing dication [((Ph₃P)₂C)P(NⁱPr₂)]²⁺ (3a²⁺). Two additional dications of general formula [((RPh₂P)₂C)P(NR′₂)]²⁺ (3b²⁺, R = 1/2 (CH₂)₃, R′ = ⁱPr; 3c²⁺, R = Ph, R′ = Cy) have been prepared. Solution and solid-state ³¹P NMR isotropic shifts for this dication class were observed around 360 ppm. Except for [3a][SbF₆]₂, the ³¹P CP/MAS NMR spectra reveal a high degree of structural disorder around the dicationic site in the solid state. Surprisingly, the synthesis of dication 3a²⁺ was only possible in the presence of AlCl₄^–, SbF₆^–, and substituted tetraarylborates, while the use of ClO₄^–, OTf^–, BF₄^–, PF₆^–, and BPh₄^– resulted in complex product mixtures. Single-crystal X-ray analysis of dications 3a²⁺ and 3c²⁺ suggested a 4π allyl-like structure for the central CPN fragment, and this has been supported through detailed theoretical investigations. Initial reactivity studies between dications 3a²⁺/3c²⁺ and PMe₃ show an equilibrium between the free dication and the target adduct. Furthermore, 3a²⁺ has been shown to be capable of O–H bond activation using water and methanol and polymerizes THF when it is dissolved in this solvent.