Cluster Harvesting in the WBr6–P System

A combined thermal scanning–X-ray diffraction (XRD) approach was performed for the WBr6–P system to detect and analyze phases in this system, including metal-rich phases generated with increasing amounts of elemental (red) phosphorus under partial PBr3 release. Phases were characterized by powder XRD. A black crystalline powder of W4(PBr)­Br10 was obtained after reduction of WBr6 with elemental phosphorus at 450 °C. The crystal structure of the new compound was found to be isotypic with the structure of W4(PCl)­Cl10 on the basis of powder XRD data. The structure of W4(PBr)­Br10 is represented by a cyclobutadiene-like tetranuclear tungsten cluster interconnected into a layered (W4(μ4-PBr)­Br6i)­Br8/2a‑a arrangement via outer bromide ligands. The μ4-capping bromophosphinidene ligand was verified by solid-state magic-angle spinning 31P NMR spectroscopy.