A Hypervalent Pentacoordinate Boron Compound with an N鈭払鈭扤 Three-Center Four-Electron Bond

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• 作者：Yuichi Hirano ; Satoshi Kojima ; Yohsuke Yamamoto
• 刊名：Journal of Organic Chemistry
• 出版年：2011
• 出版时间：April 1, 2011
• 年：2011
• 卷：76
• 期：7
• 页码：2123-2131
• 全文大小：1082K
• 年卷期：v.76,no.7(April 1, 2011)
• ISSN：1520-6904

文摘

For the purpose of synthesizing and characterizing hypervalent boron compounds with strong hypervalent interaction, we have prepared a boron compound with a tridentate ligand bearing two pyrimidine rings as nitrogen donors. X-ray analysis and molecular orbital calculations suggested that the boron compound was of hypervalent pentacoordinate structure with an N鈭払鈭扤 hypervalent bond. Thus, we have prepared the first hypervalent second row element compound with apical N coordination. A breakdown of energy contributions by DFT calculations revealed that the N鈭払鈭扤 bond energy of the pentacoordinate state ground state (13) was 2.8 kcal mol^鈭?. Implications were that the conjugation energy difference of 6.6 kcal mol^鈭? (14.2鈭?.6 kcal mol^鈭?) with the tetracoordinate state was a crucial factor for shifting stability toward the pentacoordinate structure.