Compositions are provided. A composition comprises a tungsten pentachloride compound. The tungsten pentachloride compound has an orthorhombic crystal structure as determined using Single-Crystal X-ray Diffraction. A method comprises obtaining a precursor, vaporizing the precursor to obtain a vaporized precursor, and exposing, under vapor deposition conditions, a substrate to the vaporized precursor. The precursor comprises a tungsten pentachloride compound having an orthorhombic crystal structure as determined by Single-Crystal X-Ray Diffraction. Related precursors and related methods are also provided, among other things.

Methods for synthesizing and/or purifying molybdenum compounds are provided. A method comprises obtaining a reagent; obtaining a metal trioxide compound; and contacting the reagent and the metal trioxide compound sufficient to form a reaction product comprising a molybdenum compound. Related compositions, related systems, and other related methods are provided, among other things.