Zwitterionic Base‐Stabilized Digermadistannacyclobutadiene and Tetragermacyclobutadiene |
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| Authors: | Hui‐Xian Yeong Dr Hong‐Wei Xi Dr Yongxin Li Dr Sophy Bhasi Kunnappilly Prof?Dr Bozhen Chen Prof?Dr Kai‐Chung Lau Prof?Dr Hajime Hirao Prof?Dr Kok Hwa Lim Prof?Dr Cheuk‐Wai So |
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| Institution: | 1. Division of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 (Singapore), Fax: (+65)?6791‐1961;2. Division of Chemical and Biomolecular Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459 (Singapore);3. College of Chemistry and Chemical Engineering, Graduate University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 10049 (P. R. China);4. Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Hong Kong (P. R. China) |
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| Abstract: | The syntheses of a zwitterionic base‐stabilized digermadistannacyclobutadiene and tetragermacyclobutadiene supported by amidinates and low‐valent germanium amidinate substituents are described. The reaction of the amidinate GeI dimer, LGe:]2 ( 1 , L=PhC(NtBu)2), with two equivalents of the amidinate tin(II) chloride, LSnCl] ( 2 ), and KC8 in tetrahydrofuran (THF) at room temperature afforded a mixture of the zwitterionic base‐stabilized digermadistannacyclobutadiene, L2Ge2Sn2L′2] ( 3 ; L′=LGe:), and the bis(amidinate) tin(II) compound, L2Sn:] ( 4 ). Compound 3 can also be prepared by the reaction of 1 with LArSnCl] ( 5 , LAr=tBuC(NAr)2, Ar=2,6‐iPr2C6H3) in THF at room temperature. Moreover, the reaction of 1 with the “onio‐substituent transfer” reagent 4‐NMe2‐C5H4NSiMe3]OTf ( 8 ) in THF and 4‐(N,N‐dimethylamino)pyridine (DMAP) at room temperature afforded a mixture of the zwitterionic base‐stabilized tetragermacyclobutadiene, L4Ge6] ( 9 ), the amidinium triflate, PhC(NHtBu)2]OTf ( 10 ), and Me3SiSiMe3 ( 11 ). X‐ray structural data and theoretical studies show conclusively that compounds 3 and 9 have a planar and rhombic charge‐separated structure. They are also nonaromatic. |
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| Keywords: | cyclobutadienes germanium N ligands tin zwitterions |
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