Synthesis and Structure of Boron Compounds Bearing Tridentate Ligands with 1,3-Bicarbonylbenzene Skeleton
作者:Jun-ya Nakatsuji、Yohsuke Yamamoto
DOI:10.1246/bcsj.20090342
日期:2010.7.15
In order to examine differences in structure due to the electronic nature of the oxygen ligand, several organoboron compounds bearing ester 8a–8c and amide 13a and 13b ligands were prepared and crystallographically analyzed. In the ester ligand systems, the pinacolato derivative 8a and catecholato derivative 8b took a pentacoordinate structure, while fluorenyl derivative 8c took a tetracoordinate structure instead of pentacoordinate due to the strong electrophilic nature of the boron atom. In contrast to the ester ligand systems, no pentacoordinate species were found in the amide ligand systems. The pinacolato derivative 13a is tricoordinated, and catecholato derivative 13b is tetracoordinated. These results could be due to the steric effect of the diisopropylamide ligand together with the electronic effects. The VT NMR study and the DFT calculations reveal that the energy difference between the tetracoordinate and pentacoordinate structure in 8c is very small, and indicated that the electronic nature and steric effects of the ligand greatly affect the coordination state of the boron atom.
为研究由于氧配体的电子特性导致的结构差异,合成了几种含酯配体8a–8c和酰胺配体13a、13b的有机硼化合物,并进行了结晶分析。在酯配体体系中,pinacolato衍生物8a和catecholato衍生物8b呈现五配位结构,而fluorenyl衍生物8c则由于硼原子的强亲电特性而呈现四配位结构。与酯配体体系相反,酰胺配体体系中未发现五配位物种。pinacolato衍生物13a为三配位,catecholato衍生物13b为四配位。这些结果可能受到二异丙基酰胺配体的空间效应和电子效应的影响。VT NMR研究和DFT计算表明,8c中四配位结构和五配位结构之间的能量差异非常小,表明配体的电子特性和空间效应对硼原子的配位状态具有重要影响。