The title compounds have closely related structures and intergrown crystals are very common. Both compounds have the same orthorhombic space group Cmc21 and both have – within the error limits – two translation periods in common: a = a′ = 376.1(1) pm, b = b′ = 1376.0(2) pm, c = 1319.0(1) pm, c′ = 1212.3(2) pm, Z = 8, Z′ = 4 for Mn3As2(II) and Mn5As4, respectively. Both structures were determined from one intergrown “single-crystal”. The conventional residuals are R = 0.044(669 structure factors, 61 variable parameters) and R′ = 0.048 (553 F's, 55 variables). The difference between the two compounds arises through the absence of one Mn position in Mn5As4. The structures are intermediate between those of NiAs and Ni2In. They are also closely related to the earlier determined structure of Mn3As2(I).
Zeitschrift für Kristallographie – Crystalline Materials offers a place for researchers to present results of their crystallographic studies. The journal includes theoretical as well as experimental research. It publishes Original Papers, Letters and Review Articles in manifold areas of crystallography.