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On Silylated Oxonium and Sulfonium Ions and Their Interaction with Weakly Coordinating Borate Anions
Author(s) -
Bläsing Kevin,
Labbow Rene,
Michalik Dirk,
Reiß Fabian,
Schulz Axel,
Villinger Alexander,
Walker Svenja
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201904403
Subject(s) - oxonium ion , sulfonium , dication , chemistry , homoleptic , trimethylsilyl , ion , medicinal chemistry , tetramethylammonium , crystallography , stereochemistry , salt (chemistry) , metal , organic chemistry
Attempts have been made to prepare salts with the labile tris(trimethylsilyl)chalconium ions, [(Me 3 Si) 3 E] + (E=O, S), by reacting [Me 3 Si‐H‐SiMe 3 ][B(C 6 F 5 ) 4 ] and Me 3 Si[CB] (CB − =carborate=[CHB 11 H 5 Cl 6 ] − , [CHB 11 Cl 11 ] − ) with Me 3 Si‐E‐SiMe 3 . In the reaction of Me 3 Si‐O‐SiMe 3 with [Me 3 Si‐H‐SiMe 3 ][B(C 6 F 5 ) 4 ], a ligand exchange was observed in the [Me 3 Si‐H‐SiMe 3 ] + cation leading to the surprising formation of the persilylated [(Me 3 Si) 2 (Me 2 (H)Si)O] + oxonium ion in a formal [Me 2 (H)Si] + instead of the desired [Me 3 Si] + transfer reaction. In contrast, the expected homoleptic persilylated [(Me 3 Si) 3 S] + ion was formed and isolated as [B(C 6 F 5 ) 4 ] − and [CB] − salt, when Me 3 Si‐S‐SiMe 3 was treated with either [Me 3 Si‐H‐SiMe 3 ][B(C 6 F 5 ) 4 ] or Me 3 Si[CB]. However, the addition of Me 3 Si[CB] to Me 3 Si‐O‐SiMe 3 unexpectedly led to the release of Me 4 Si with simultaneous formation of a cyclic dioxonium dication of the type [Me 3 Si‐μO‐SiMe 2 ] 2 [CB] 2 in an anion‐mediated reaction. DFT studies on structure, bonding and thermodynamics of the [(Me 3 Si) 3 E] + and [(Me 3 Si) 2 (Me 2 (H)Si)E] + ion formation are presented as well as mechanistic investigations on the template‐driven transformation of the [(Me 3 Si) 3 E] + ion into a cyclic dichalconium dication [Me 3 Si‐μE‐SiMe 2 ] 2 2+ .