New aspects of acid-assisted nucleophilic substitution reactions of 11-vertex nido-carboranes. (1st March 2022)

• Record Type: Journal Article
• Authors: Vinogradov, Mikhail M.; Nelyubina, Yulia V.; Aliyeu, Tseimur M.
• Is Part Of: Polyhedron. Volume 214(2022)
• Publication Date: 2022-03-01
• Subjects: Carboranes -- Isomerization -- Acid -- Nucleophilic substitution -- DFT; Chemistry, Inorganic -- Periodicals; Chimie inorganique -- Périodiques; Organometaalverbindingen; Anorganische chemie; 546.05
• DOI: 10.1016/j.poly.2022.115654
• Languages: English
• ISSNs: 0277-5387

Abstract

Graphical abstract: A comparative study of reactivity of nido -carboranes in acid-induced nucleophilic substitution reaction and unique behavior of carborane with covalently binded cage carbon atoms are presented. Abstract: Reactions of the nido -carborane salts Me4 N[7, 8-R, R-7, 8- nido -C2 B9 H10 ] (R, R = Me2 ; R, R = o-C6 H4 (CH2 )2 ) with Me2 S in the presence of triflic acid give a mixture of isomeric carboranes 9-Me2 S-7, 8-R, R-7, 8- nido -C2 B9 H9 and 10-Me2 S-7, 8-R, R-7, 8- nido -C2 B9 H9 . In contrast, Me4 N[7, 8-(CH2 )3 –7, 8- nido -C2 B9 H10 ] affords the only isomer 10-Me2 S-7, 8-(CH2 )3 –7, 8- nido -C2 B9 H9 . Interaction of Me4 N[7, 8-(CH2 )3 –7, 8- nido -C2 B9 H10 ] and dimethyl sulfoxide in acidic conditions leads to the formation of a product 10-Me2 SO-7, 8-(CH2 )3 –7, 8- nido -C2 B9 H9 in which, according to the SC-XRD, dimethyl sulfoxide molecule attaches to nido -carborane cage through an oxygen atom. The half-peak potential of the first oxidation wave of nido -carboranes correlates well with their ability to undergo acid-assisted nucleophilic substitution reactions. Thermal isomerization of 10-Me2 S substituted nido -carboranes to 9-Me2 S isomers was observed at higher temperatures than acid-assisted nucleophilic substitution and could proceed with the formation of 11-vertex closo -carboranes as intermediates according to the DFT study.