A Retro Diels鈥揂lder Route to Diphosphorus Chemistry: Molecular Precursor Synthesis, Kinetics of P2 Transfer to 1,3-Dienes, and Detection of P2 by Molecular Beam Mass Spectrometry
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- 作者：Alexandra Velian ; Matthew Nava ; Manuel Temprado ; Yan Zhou ; Robert W. Field ; Christopher C. Cummins
- 刊名：Journal of the American Chemical Society
- 出版年：2014
- 出版时间：October 1, 2014
- 年：2014
- 卷：136
- 期：39
- 页码：13586-13589
- 全文大小：342K
- ISSN：1520-5126
文摘
The transannular diphosphorus bisanthracene adduct P2A2 (A = anthracene or C14H10) was synthesized from the 7-phosphadibenzonorbornadiene Me2NPA through a synthetic sequence involving chlorophosphine ClPA (28鈥?5%) and the tetracyclic salt [P2A2Cl][AlCl4] (65%) as isolated intermediates. P2A2 was found to transfer P2 efficiently to 1,3-cyclohexadiene (CHD), 1,3-butadiene (BD), and (C2H4)Pt(PPh3)2 to form P2(CHD)2 (>90%), P2(BD)2 (69%), and (P2)[Pt(PPh3)2]2 (47%), respectively, and was characterized by X-ray diffraction as the complex [CpMo(CO)3(P2A2)][BF4]. Experimental and computational thermodynamic activation parameters for the thermolysis of P2A2 in a solution containing different amounts of CHD (0, 4.75, and 182 equiv) have been obtained and suggest that P2A2 thermally transfers P2 to CHD through two competitive routes: (i) an associative pathway in which reactive intermediate [P2A] adds the first molecule of CHD before departure of the second anthracene, and (ii) a dissociative pathway in which [P2A] fragments to P2 and A prior to addition of CHD. Additionally, a molecular beam mass spectrometry study on the thermolysis of solid P2A2 reveals the direct detection of molecular fragments of only P2 and anthracene, thus establishing a link between solution-phase P2-transfer chemistry and production of gas-phase P2 by mild thermal activation of a molecular precursor.