Stepwise Deprotonation of a Thiol-Functionalized Bis(1,2,4-triazolium) Salt as a Selective Route to Heterometallic NHC Complexes

Heterometallic NHC complexes have
been selectively prepared at
room temperature directly from an azolium salt in a two-step procedure.
In the unsymmetrically substituted bis­(1,2,4-triazolium) ligand precursor,
one of the m-xylylene-bridged triazolium units features
an unprotected o-thiophenol substituent. This renders
possible a selective deprotonation and in situ monopalladation at
the NHC–thiolato unit. The obtained palladium­(II) complex possesses
two pendant triazolium units as vacant binding sites. After a second
deprotonation/metalation step, a heterodinuclear palladium­(II) gold­(I)
complex and a heterotrinuclear palladium­(II) dicopper­(I) complex were
obtained. In the latter, two metal centers are connected via a thiolato
bridge.