Crystal structures of VSn2, NbSn2 and CrSn2 with Mg2Cu-type structure and NbSnSb with CuAl2-type structure

Several binary stannides of the early transition metals T have been reported with the composition T₂Sn₃ previously. However, the present structure refinements from single-crystal X-ray data show that they have the compositions VSn₂, NbSn₂ and CrSn₂ (R = 0.028, R = 0.018 and R = 0.021 with 17 variable parameters and 828, 512 and 440 structure factors respectively). Their orthorhombic Mg₂Cu-type structure is closely related to the structures of MoSn₂ (Mg₂Ni type) and CuAl₂. The latter structure type was confirmed for NbSnSb by a structure refinement from single-crystal data (R = 0.010 for eight variables and 254 F values). Electrical conductivity measurements show CrSn₂ and MoSn₂ to be metallic conductors.