Crystal structure and properties of MgCo₄Ge₆

MgCo₄Ge₆ is a novel compound in the ternary system Mg-Co-Ge. Single crystals for a structure analysis were obtained from mixtures of the elements at high temperatures in sealed tantalum ampoules. The tetragonal structure [I4₂m; a = 6.1725(9) and c = 8.660(2) Å; YRu ₄Sn₆ structure type] was determined by X-ray single crystal analysis and refined to R₁ = 0.027 for all data. The electronic structure is discussed by means of density of states and band-structure analyses on the basis of density functional theory. Chemical bond analysis is performed using the electron localization function (ELF). The catalytic properties of the polar intermetallic alloy with respect to the selective hydrogenation of α,β-unsaturated aldehydes are discussed and compared with those of the recently investigated MgCo₆Ge ₆.