Dibenzo[b,f]phosphepines: Novel Phosphane鈥揙lefin Ligands for Transition Metals

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• 作者：Volodymyr Lyaskovskyy ; Relinde J. A. van Dijk-Moes ; Sebastian Burck ; Wojciech I. Dzik ; Martin Lutz ; Andreas W. Ehlers ; J. Chris Slootweg ; Bas de Bruin ; Koop Lammertsma
• 刊名：Organometallics
• 出版年：2013
• 出版时间：January 28, 2013
• 年：2013
• 卷：32
• 期：2
• 页码：363-373
• 全文大小：556K
• 年卷期：v.32,no.2(January 28, 2013)
• ISSN：1520-6041

文摘

New, stable heterobidentate phosphane鈥搊lefin ligands based on the dibenzo[b,f]phosphepine backbone are reported together with their redox properties and coordination chemistry to rhodium(I). The X-ray crystal structures and DFT calculations show different conformations for the P-phenyl (6a) and P-mesityl (6b) derivatives. Cyclic voltammetry (vs Fc/Fc⁺) of 6a supported by UV鈥搗is spectroelectrochemistry showed two cathodic waves, a reversible one at E_1/2 = 鈭?.62 V (I_f/I_b = 1.0) and a quasi-reversible (I_f/I_b 鈮?1.2) one at E_1/2 = 鈭?.03 V. Reduction with sodium afforded a mixture of the radical anion [6a^{鈥?/sup>]鈭?/sup>, characterized by EPR spectroscopy, and dianion [6a]2鈥?/sup>, for which an X-ray crystal structure was obtained. Both 6a and 6b bind to RhI centers, giving rise to 3:1 (8a) and 2:1 (8b) ligand:Rh complexes, respectively. Two dibenzo[b,f]phosphepines in 8a and 8b act as heterobidentate ligands in which both the phosphorus atom and the olefinic double bond coordinate to rhodium, but the third ligand in 8a binds as a monodentate P-donor. The cyclic voltammogram of 8b showed two close-lying waves, a one-electron reversible wave at 鈭?.45 V and a two-electron quasi-reversible wave at 鈭?.80 V (I_f/I_b 鈮?1.3). 8a showed a reversible wave at 鈭?.71 V and irreversible waves at lower potentials.}