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A Facile Route to Backbone‐Tethered N‐Heterocyclic Carbene (NHC) Ligands via NHC to aNHC Rearrangement in NHC Silicon Halide Adducts
Author(s) -
Schneider Heidi,
Schmidt David,
Radius Udo
Publication year - 2015
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.201406264
Subject(s) - chemistry , carbene , adduct , deprotonation , sodium hydride , halide , hydride , medicinal chemistry , ligand (biochemistry) , catalysis , salt (chemistry) , polymer chemistry , stereochemistry , metal , organic chemistry , ion , receptor , biochemistry
Abstract The reaction of 1,3‐diisopropylimidazolin‐2‐ylidene ( i Pr 2 Im) with diphenyldichlorosilane (Ph 2 SiCl 2 ) leads to the adduct ( i Pr 2 Im)SiCl 2 Ph 2 1 . Prolonged heating of isolated 1 at 66 °C in THF affords the backbone‐tethered bis(imidazolium) salt [( a H i Pr 2 Im) 2 SiPh 2 ] 2+ 2 Cl − 2 (“ a ” denotes “abnormal” coordination of the NHC), which can be synthesized in high yields in one step starting from two equivalents of i Pr 2 Im and Ph 2 SiCl 2 . Imidazolium salt 2 can be deprotonated in THF at room temperature using sodium hydride as a base and catalytic amounts of sodium tert ‐butoxide to give the stable N‐heterocyclic dicarbene ( a i Pr 2 Im) 2 SiPh 2 3 , in which two NHCs are backbone‐tethered with a SiPh 2 group. This easy‐to‐synthesize dicarbene 3 can be used as a novel ligand type in transition metal chemistry for the preparation of dinuclear NHC complexes, as exemplified by the synthesis of the homodinuclear copper(I) complex [{ a (ClCu i Pr 2 Im)} 2 SiPh 2 ] 4 .