Core–shell particles Fe₂P@Au have been prepared beginning with Fe₂P nanorods, nanocrosses and nanobundles prepared from the solvothermal decomposition of H₂Fe₃(CO)₉(μ₃-P^tBu). Iron phosphide structures can be produced from a single-source organometallic precursor with morphological control by varying the surfactant conditions to yield fiber bundles and dumbbell-shaped bundles ranging from nanometers to microns. Derivatization of the surfaces with γ-aminobutyric acid was used to attach Au nanoparticle seeds to the surface of the Fe₂P nanoparticles followed by completion of the Au shell by reduction with formaldehyde or aqueous HAuCl₄/CO, with the latter giving somewhat better results. Shell thickness ranged from an incomplete, partially coated Au shell to a thickness of 65 ± 21 nm by varying the amount of gold decorated precursor particles. Increasing the thicknesses of the Au shells produced a redshift in the plasmonic resonance of the resulting structures as was observed previously for FeO_x@Au.