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Chloride‐Induced Aufbau of Perchlorinated Cyclohexasilanes from Si 2 Cl 6 : A Mechanistic Scenario
Author(s) -
Tillmann Jan,
Meyer Lioba,
Schweizer Julia I.,
Bolte Michael,
Lerner HansWolfram,
Wagner Matthias,
Holthausen Max C.
Publication year - 2014
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.201402655
Subject(s) - adduct , chemistry , chloride , stoichiometry , silanes , reaction mechanism , inorganic chemistry , medicinal chemistry , crystallography , catalysis , organic chemistry , silane
A surprisingly simple preparative procedure, addition of Si 2 Cl 6 to a solution of [ n Bu 4 N]Cl in CH 2 Cl 2 , leads to the formation of the chloride‐complexed cyclic dianions [Si 6 Cl 12 ⋅ 2Cl] 2− , [(SiCl 3 )Si 6 Cl 11 ⋅ 2Cl] 2− , or [1,y‐(SiCl 3 ) 2 Si 6 Cl 10 ⋅ 2Cl] 2− (y=1, 3, 4), depending on the stoichiometric ratio of the reactants and the reaction temperature (25–85 °C). Below −40 °C the open‐chain oligosilane chloride adducts [Si 3 Cl 9 ] − , [Si 3 Cl 10 ] 2− , [Si 4 Cl 11 ] − , and [Si 6 Cl 15 ] − are formed, again depending on the reaction conditions chosen. All species were characterized by X‐ray crystallography. The underlying reaction mechanism is elucidated by DFT calculations. It incorporates all experimental findings and involves a few key elementary steps: 1) chloride‐induced liberation of SiCl 3 − or higher silanides, 2) their addition to neutral silanes yielding larger oligosilane chloride adducts, 3) dimerization of larger silanides to (substituted) cyclohexasilane dichloride adducts with inverse sandwich structure.