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Stable N‐Heterocyclic Carbene Adducts of Arylchlorosilylenes and Their Germanium Homologues
Author(s) -
Filippou Alexander C.,
Chernov Oleg,
Blom Burgert,
Stumpf Kai W.,
Schnakenburg Gregor
Publication year - 2010
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.200903019
Subject(s) - carbene , adduct , natural bond orbital , chemistry , density functional theory , germanium , bond dissociation energy , dissociation (chemistry) , crystallography , medicinal chemistry , computational chemistry , organic chemistry , catalysis , silicon
The first N‐heterocyclic carbene adducts of arylchlorosilylenes are reported and compared with the homologous germanium compounds. The arylsilicon(II) chlorides SiArCl(Im‐Me 4 ) [Ar=C 6 H 3 ‐2,6‐Mes 2 (Mes=C 6 H 2 ‐2,4,6‐Me 3 ), C 6 H 3 ‐2,6‐Trip 2 (Trip=C 6 H 2 ‐2,4,6‐ i Pr 3 )] were obtained selectively on dehydrochlorination of the arylchlorosilanes SiArHCl 2 with 1,3,4,5‐tetramethylimidazol‐2‐ylidene (Im‐Me 4 ). The analogous arylgermanium(II) chlorides GeArCl(Im‐Me 4 ) were prepared by metathetical exchange of GeCl 2 (Im‐Me 4 ) with LiC 6 H 3 ‐2,6‐Mes 2 or addition of Im‐Me 4 to GeCl(C 6 H 3 ‐2,6‐Trip 2 ). All compounds were fully characterized. Density functional calculations on ECl(C 6 H 3 ‐2,6‐Trip 2 )(Im‐Me 4 ), where E=Si, Ge, at different levels of theory show very good agreement between calculated and experimental bonding parameters, and NBO analyses reveal similar electronic structures of the two aryltetrel(II) chlorides. The low gas‐phase Gibbs free energy of bond dissociation of SiCl(C 6 H 3 ‐2,6‐Trip 2 )(Im‐Me 4 ) (Δ ${G{{{\circ}\hfill \atop {\rm calcd}\hfill}}}$ =28.1 kJ mol −1 ) suggests that the carbene adducts SiArCl(Im‐Me 4 ) may be valuable transfer reagents of the arylsilicon(II) chlorides SiArCl.