Methods for producing nanoparticles of metal alloys and the nanoparticles so produced are provided. The methods include addition of surfactant and cationic metal to a novel reagent complex between zero-valent metal and a hydride. The nanoparticles of zero-valent metal alloys produced by the method include ˜7 nm zero-valent manganese-bismuth useful in fabricating a less expensive permanent magnet.