Syntheses and Structures of Hypervalent Pentacoordinate Carbon and Boron Compounds Bearing an Anthracene Skeleton − Elucidation of Hypervalent Interaction Based on X-ray Analysis and DFT Calculation Makoto Yamashita Yohsuke Yamamoto Kin-ya Akiba Daisuke Hashizume Fujiko Iwasaki Nozomi Takagi Shigeru Nagase 10.1021/ja0438011.s003 https://acs.figshare.com/articles/dataset/Syntheses_and_Structures_of_Hypervalent_Pentacoordinate_Carbon_and_Boron_Compounds_Bearing_an_Anthracene_Skeleton_Elucidation_of_Hypervalent_Interaction_Based_on_X_ray_Analysis_and_DFT_Calculation/3294031 Pentacoordinate and tetracoordinate carbon and boron compounds (<b>27</b>, <b>38</b>, <b>50</b><b>−</b><b>52</b>, <b>56</b><b>−</b><b>61</b>) bearing an anthracene skeleton with two oxygen or nitrogen atoms at the 1,8-positions were synthesized by the use of four newly synthesized tridentate ligand precursors. Several carbon and boron compounds were characterized by X-ray crystallographic analysis, showing that compounds <b>27</b>, <b>56</b><b>−</b><b>59</b> bearing an oxygen-donating anthracene skeleton had a trigonal bipyramidal (TBP) pentacoordinate structure with relatively long apical distances (ca. 2.38−2.46 Å). Despite the relatively long apical distances, DFT calculation of carbon species <b>27</b> and boron species <b>56</b> and experimental accurate X-ray electron density distribution analysis of <b>56</b> supported the existence of the apical hypervalent bond even though the nature of the hypervalent interaction between the central carbon (or boron) and the donating oxygen atom was relatively weak and ionic. On the other hand, X-ray analysis of compounds <b>50</b><b>−</b><b>52</b> bearing a nitrogen-donating anthracene skeleton showed unsymmetrical tetracoordinate carbon or boron atom with coordination by only one of the two nitrogen-donating groups. It is interesting to note that, with an oxygen-donating skeleton, the compound <b>61</b> having two chlorine atoms on the central boron atom showed a tetracoordinate structure, although the corresponding compound <b>60</b> with two fluorine atoms showed a pentacoordinate structure. The B−O distances (av 2.29 Å) in <b>60</b> were relatively short in comparison with those (av 2.44 Å) in <b>59</b> having two methoxy groups on the central boron atom, indicating that the B−O interaction became stronger due to the electron-withdrawing nature of the fluorine atoms. 2005-03-30 00:00:00 skeleton DFT Calculation Pentacoordinate pentacoordinate structure Boron Compounds Bearing boron species 56 TBP unsymmetrical tetracoordinate carbon boron atom anthracene apical distances Hypervalent Pentacoordinate Carbon apical hypervalent bond tridentate ligand precursors carbon species 27 fluorine atoms boron compounds analysis