Catalysis Design for Ring-Opening Polymerization of Cyclic Esters: 1. Group 1 Metal and Thallium(I) Trispyrazolylborate Complexes with Hemilabile Ligands
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- 作者：Malcolm H. Chisholm ; Judith C. Gallucci ; Gü ; lah Yaman
- 刊名：Inorganic Chemistry
- 出版年：2007
- 出版时间：October 15, 2007
- 年：2007
- 卷：46
- 期：21
- 页码：8676 - 8683
- 全文大小：396K
- 年卷期：v.46,no.21(October 15, 2007)
- ISSN：1520-510X
文摘
The synthesis of 3-(2-methoxy-1,1-dimethylethyl)pyrazole, pz*H is described together with its reactions with theborohydrides MBH4, where M = Li, Na, and K, under melt conditions. At 180 C, this procedure leads to a mixtureof products for M = Li, and at higher temperatures, a derivative LiTp'pz*H, 1, is isolated, wherein a B-H bond anda methyl group have been eliminated and a B-O bond has been formed. For M = Na, the reaction proceeds togive the tris-pyrazolylborate derivative NaTp*, 2, but at higher temperatures the tetra-pyrazolylborate complex NaB(pz*)4, 3, is obtained. The reactions involving KBH4 and pz*H yield the dinuclear complex K2(Tp*)2pz*H, 4. Thereaction between NaTp* and TlOAc in CH2Cl2 at room temperature leads to the formation of TlTp*, 5, along withNaOAc. Thallium 5 reacts with methyllithium in diethylether to give LiTp*, 6, and thallium metal, and, similarly, 5and KH react in tetrahydrofuran to give KTp*, 7 and Tl(0). 1-7 have been characterized by elemental analysis,NMR spectroscopy, and by single-crystal X-ray studies, the latter of which reveal the versatile modes of binding forthis new ligand bearing hemilabile ether appendages.