Synthesis, Structural Analysis, and Functional Group Interconversion in the [closo‐B10H8‐1,10‐X2]2– (X = CN, [OCRNMe2]+, OCOR, and [OH2]+) Derivatives

Abstract

Derivatives [closo‐B10H8‐1,10‐(CN)2]2– and [closo‐B10H8‐1,10‐(OCHNMe2)2], efficiently obtained from [closo‐B10H8‐1,10‐(IPh)2] by nucleophilic substitution with CN– and DMF, were envisioned as precursors to diacid [closo‐B10H8‐1,10‐(COOH)2]2– and to dihydroxy derivative [closo‐B10H8‐1,10‐(OH)2]2–, respectively. Attempts at hydrolysis or reduction of the dinitrile gave no reaction or complex mixtures of products. In contrast, the DMF adduct was cleanly hydrolyzed to diformate [closo‐B10H8‐1,10‐(OCHO)2]2– and subsequently to protonated dihydroxy [closo‐B10H8‐1,10‐(OH2)2]. The latter was O‐acylated with PhCOCl. Crystal and molecular structures of five derivatives were established by single crystal XRD methods and compared to those for other [closo‐B10H8‐1,10‐X2]2– derivatives. Trends in molecular geometry in the series and also reactivity of the dinitrile and intermediates were corroborated and correlated with DFT results (B3LYP/TZVP) by analysis of bonding, charge distribution and vibrational frequencies.