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Reprogramming of a Malonic N‐Heterocyclic Carbene: A Simple Backbone Modification with Dramatic Consequences on the Ligand's Donor Properties
Author(s) -
César Vincent,
Lugan Noël,
Lavigne Guy
Publication year - 2010
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200901113
Subject(s) - chemistry , carbene , dichloromethane , adduct , deprotonation , ligand (biochemistry) , medicinal chemistry , nucleophile , triethylamine , yield (engineering) , ruthenium , cyclooctadiene , stereochemistry , organic chemistry , catalysis , biochemistry , receptor , ion , materials science , solvent , metallurgy
Abstract Reaction of N , N′ ‐dimesitylformamidine with dimethylmalonyl dichloride in dichloromethane in the presence of an excess of triethylamine gives the 2‐chloro‐4,5‐dioxohexahydropyrimidine 1 . The corresponding diamidocarbene 3 is generated in situ by further deprotonation with KHMDS at –40 °C and identified by trapping with S 8 to give the fully characterized (including X‐ray structure) sulfur adduct 4 . It also reacts with [RhCl(cod)] 2 to yield the NHC complex [RhCl( 3 )(cod)] ( 5 ) (characterized also by X‐ray structure). The donor properties of 3 were evaluated against the established IR [ ν (CO)] scale from [RhCl( 3 )(CO) 2 ] ( 6 ). The average value of ν (CO) = 2045 cm –1 indicates that the diamidocarbene 3 is much less nucleophilic than structurally relevant six‐membered NHCs including the anionic diaminocarbenes previously reported in our group.