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An N‐Heterocyclic Carbene with a Saturated Backbone and Spatially‐Defined Steric Impact
Author(s) -
Laidlaw Gillian,
Wood Susanna H.,
Kennedy Alan R.,
Nelson David J.
Publication year - 2019
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201800423
Subject(s) - steric effects , carbene , chemistry , ligand (biochemistry) , aryl , catalysis , iridium , saturation (graph theory) , palladium , metal , electronic effect , combinatorial chemistry , polymer chemistry , medicinal chemistry , stereochemistry , organic chemistry , biochemistry , alkyl , receptor , mathematics , combinatorics
The synthesis and coordination chemistry of a saturated analogue of a “bulky‐yet‐flexible” N‐heterocyclic carbene (NHC) ligand are described. “SIPaul” is a 4,5‐dihydroimidazol‐2‐ylidene ligand with unsymmetrical aryl N ‐substituents, and is one of the growing class of “bulky‐yet‐flexible” NHCs that are sufficiently bulky to stabilize catalytic intermediates, but sufficiently flexible that they do not inhibit productive chemistry at the central metal atom. Here, the synthesis of SIPaul.HCl and its complexes with copper, silver, iridium, palladium, and nickel, and its selenourea, are reported. The steric impact of the ligand is quantified using percent buried volume (% V bur ), whereas the electronic properties are probed and quantified using the Tolman Electronic Parameter (TEP) and δ Se of the corresponding selenourea. This work shows that despite the often very different performance of saturated versus unsaturated carbenes in catalysis, the effect of backbone saturation on measurable properties is very small.