Acylchalcogenourea Complexes of Silver(I)

Acylthio- or acylselenoureas react with silver(I) oxide to form tetranuclear silver(I) complexes containing the deprotonated acylchalcogenourea ligands bound to the silver atoms through the chalcogen and oxygen atoms. These tetrasilver(I) species react with either 4 or 8 equiv. of a phosphine to afford either dinuclear silver(I) phosphine complexes or tetrahedral silver diphosphine complexes. In these compounds, the acylchalcogenourea ligands form six-membered rings by coordinating to the metal atom through the chalcogen and oxygen atoms. In one case, we observed a very rare example of an acylthiourea ligand coordinated through the nitrogen and sulfur atoms to form a four-membered ring. A silver(I) complex containing a deprotonated acylselenourea and an N-heterocyclic carbene ligand is also reported. This was prepared from the corresponding acetate derivative and the acylselenourea; in this case, the acetate acts as the base. All of the reported compounds were characterized by spectroscopic techniques, and many were also studied by single-crystal X-ray diffraction.