Ligand-Directed Metalation of a Gold Pyrazolate Cluster

Metalation of [Au- n (mu-L)( n )] (HL =3-[pyrid-2-yl]-5-tertbutyl-1H-pyrazole; n = 3 or 4) with AgBF4 yields [Ag2Au4(mu(3)-L)(4)][BF4](2), where two edges of the Au-4 square are spanned by Ag+ ions coordinated to its pendantpyridyl groups. Treatment of [Au- n (mu-L)( n )] with [Cu(NCMe)(4)]PF6 affords a metalloligand helicate [Cu2Au2(mu-L)(4)][PF6](2), via oxidation of the copper and partial fragmentation ofthe cluster. Solid "[AuL]" (HL = 3-[pyrid-2-yl]-5-tertbutyl-1H-pyrazole) can be crystallized as cyclic [Au-3(mu-L)(3)] and [Au-4(mu-L)(4)] clusters from different solvents. The crystallinetetramer contains a square Au-4 core with an HT:TH:TH:HTarrangement of ligand substituents, which preorganizes the clusterto chelate to additional metal ions via its pendant pyridyl groups.The addition of 0.5 equiv of AgBF4 to [AuL] yields [Ag2Au4(mu(3)-L)(4)][BF4](2), where two edgesof the Au-4 square are spanned by Ag+ ions viametallophilic Ag center dot center dot center dot Au contacts. Treatment of [AuL] with [Cu(NCMe)(4)]PF6 affords themetalloligand helicate [Cu2Au2(mu-L)(4)][PF6](2), via oxidationof the copper and partial fragmentation of the cluster.