Regioselective Functionalization of the [ closo-1-CB9H10]- Anion through Iodonium Zwitterions

Remigiusz Żurawiński; Rafał Jakubowski; Sławomir Domagała; Piotr Kaszyński; Krzysztof Woźniak

doi:10.1021/acs.inorgchem.8b01701

Regioselective Functionalization of the [ closo-1-CB₉H₁₀]^- Anion through Iodonium Zwitterions

Inorg Chem. 2018 Aug 20;57(16):10442-10456. doi: 10.1021/acs.inorgchem.8b01701. Epub 2018 Aug 1.

Authors

Remigiusz Żurawiński^{1

2}, Rafał Jakubowski^{1

2}, Sławomir Domagała³, Piotr Kaszyński^{1

2

4}, Krzysztof Woźniak³

Affiliations

¹ Centre of Molecular and Macromolecular Studies , Polish Academy of Sciences , 90-363 Łódź , Poland.
² Department of Chemistry , Middle Tennessee State University , Murfreesboro , Tennessee 37130 , United States.
³ Department of Chemistry , University of Warsaw , 02-089 Warsaw , Poland.
⁴ Faculty of Chemistry , University of Łódź , 91-403 Łódź , Poland.

PMID: 30067341
DOI: 10.1021/acs.inorgchem.8b01701

Abstract

Reactions of [ closo-1-CB₉H₉-1-R]^- (2, R = H, COOH, C₅H₁₁) with PhI(OAc)₂ lead to mixtures of regioisomers [ closo-1-CB₉H₈-1-R-6-IPh] (5[6]) and [ closo-1-CB₉H₈-1-R-10-IPh] (5[10]) in ratios of ∼3:1 to 1:1, of which the former isomer undergoes selective reactions with nucleophiles (MeCN, pyridine, MeC(═NH)NH₂, CN^-). The products and the unreacted 10-isomers 5[10] are separated achieving kinetic resolution of the isomeric iodonium zwitterions. Pure 5[10] is reacted with nucleophiles (pyridine, 4-C₇H₁₅OPyridine, Me₂NCHS, PhCO₂^-, CN^-, N₃^-, I^-, MeC(═NH)NH₂, and MeCN), giving substitution products. The mechanism of the substitution is investigated with density functional theory (DFT) methods. Some of the nucleophilic substitution products are transformed further, expanding the scope of available functional groups for the [ closo-1-CB₉H₁₀]^- anion. Four derivatives are characterized with single-crystal XRD methods: [ closo-1-CB₉H₉-10-N₂] (4[10]a), [ closo-1-CB₉H₉-6-NC₅H₅] (9[6]a), [ closo-1-CB₉H₉-10-NC₅H₅] (9[10]a), and [ closo-1-CB₉H₉-10-NHC(NH₂)Me] (10[10]a). Spectroscopic data for selected derivatives are interpreted in terms of transmission of electronic effects through the { closo-1-CB₉} cluster (NMR) and interaction with substituents (IR, UV). The latter results are compared to those of TD-DFT computational methods.