The crystal structure and magnetic properties of Sm-3(Fe, V)(29)N-X compounds were investigated. It was found that the novel nitride, Sm-3(Fe, V)(29)N-2, is more stable than Sm-3(Fe, V)(29)N-4 in the atmosphere with low nitrogen pressure. The x-ray and electron diffraction studies show that the nitrides retain the same crystal structure as Sm-3(Fe, V)(29). The lattice parameters of Sm-3(Fe, V)(29)N-2 are a=1.084 nm, b=0.870 nm, c=0.985 nm, and beta=97.06 degrees. (C) 1999 American Institute of Physics. [S0021-8979(99)56608-5].