SYNTHESIS AND CRYSTAL STRUCTURE OF MN4AS3 AND ITS RELATION TO OTHER MANGANESE ARSENIDES

摘要

The title compound was prepared by reaction of the elements at 700 degrees C in the presence of iodine, Its crystal structure-determined from single-crystal diffractometer data-is isotypic with that of beta-V4As3: C2/m, a 1341.1(2) pm, b = 369.34(5) pm, c = 962.8(1) pm, beta = 101.97(1)degrees, and R = 0.027 for 1394 structure factors and 62 variable parameters. Mn4As3 is the member with n = 2 of a series of closely related structures with the general composition Mn2+nAs1+n. Other members of this series are the modification III of Mn3As2 (with n = 1) and the two closely related structures of MnAs (with n = infinity). The structural relationships of these compounds and the other known manganese arsenides Mn2As, Mn3As2(I), Mn3As2(II), and Mn5As4 are pointed out, emphasizing the numerous Mn-Mn bonds in these arsenides with high manganese content. (C) 1995 Academic Press, Inc. [References: 25]