PO 2 3- and AsO 3- : Pnictogenide Ligands in the Highly Charged Re 4 Cluster Anions [{Re 4 (PO) 3 (PO 2 )}(CN) 12 ] 8- , [{Re 4 As 2 (AsO) 2 }(CN) 12 ] 8- , and [{Re 4 (AsO) 4 }(CN) 12 ] 8

New tetrahedral anionic rhenium cluster complexes [{Re (PO) (PO )}(CN) ] (1) and [{Re As (AsO) }(CN) ] (2) have been synthesized by the reaction of ReI with NaCN and P or KCN and As , respectively. Compound 2 was further oxidized by aqueous H O to produce the cluster anion [{Re (AsO) }(CN) ] (3). The anions contain new pnictogen/oxygen-based ligands, PO and AsO , which were stabilized by the coordination to the triangular faces of the tetrahedral Re metallocluster in μ -mode. All three compounds were crystallized as either sodium or potassium salts, and their crystal structures were determined by single crystal X-ray diffraction analysis.