Abstract
The title compound crystallizes in monoclinic system P21/c. The parameters of the unit cell are: a=6.856(5)Å; b=13.070(5)Å; c=11.370(2)Å; β=98.63(3)°; V=1007.2(5)Å3 and Z=4. The anionic framework of the compound is built up from infinite layers linked together by Mn-As-O bridges and by edge-sharing MnO6 octahedra to form a three dimensional framework having two kinds of tunnels. The first one, containing K+ cations, is parallel to the a axis and the second one containing Na+ cations is parallel to [001] direction. Complementary infrared (IR) and complex impedance (CI) spectroscopies studies were carried out.