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.