Solid “[AuL]” (HL= 3-[pyrid-2-yl]-5-tertbutyl-1H-pyrazole) can be crystallized as cyclic [Au3(μ-L)3] and [Au4(μ-L)4] clusters from different solvents. The crystalline
tetramer contains a square Au4core with an HT:TH:TH:HT
arrangement of ligand substituents, which preorganizes the cluster
to chelate to additional metal ions via its pendant pyridyl groups.
The addition of 0.5 equiv of AgBF4to [AuL] yields [Ag2Au4(μ3-L)4][BF4]2, where two edges
of the Au4square are spanned by Ag+ions via
metallophilic Ag···Au contacts. Treatment of [AuL] with [Cu(NCMe)4]PF6affords the
metalloligand helicate [Cu2Au2(μ-L)4][PF6]2, via oxidation
of the copper and partial fragmentation of the cluster.