Synthesis, Structure, and Coordination Chemistry of Phosphine-Functionalized Imidazole/Imidazolium Salts and Cleavage of a C–P Bond in an NHC–Phosphenium Salt using a Pd(0) Precursor

A simple
method involving metal–halogen exchange reaction(s)
to prepare various phosphine-functionalized imidazole/imidazolium
salts and their coordination chemistry with different metal precursors
has been described. Interestingly, the reaction of 1,3-dimethyl-2-(diphenylphosphino)-4-iodoimidazolium
iodide (6) with Pd2(dba)3 in the
presence of triphenylphosphine affords a Pd­(II)–NHC complex
which involves the cleavage of a C–P bond presumably occurring
via oxidative addition of Pd(0) to a C–I bond to afford an
in situ generated Pd­(II) species, which subsequently reacts with another
1 equiv of 6 through the phosphine center to form an
adduct followed by a dephosphinylation reaction.