Synthesis and Structure of BiMnVO5 and BiMnAsO5

The isostructural compounds BiMnVO5 and BiMnAsO5 have been prepared for the first time. Their structures were determined from single-crystal X-ray diffraction data in space group P with Z=2. For the vanadate a=6.912(4) ?, b=6.991(2) ?, c=5.354(1) ?, alpha= 108.55(2)°, beta=95.98(4)° and r=109.73(4)°. For the arsenate a=6.868(1) ?, b=6.905(2) ?, c=5.360(1) ?, alpha=109.47(2)°, beta=95.91(2)°, and gamma=109.32(2)°. The structures are based on MnO6 octahedra sharing one edge to form Mn2O10 groups, Bi2O8 groups, and MO4 tetrahedra with M=As or V. The same moieties are found in the BiMnPO5 structure, which has monoclinic symmetry. However, the triclinic structures for BiMnVO5 and BiMnAsO5 cannot be regarded as distorted versions of the monoclinic BiMnPO5 structure because the connectivity of the moieties is distinctly different.