V2Cu3Ga8, Mo2Cu3Ga8 and W2Cu3Ga8—New compounds with a novel order variant of a bcc packing and motifs of self-similarity

Single crystals of the new compounds TM2Cu3Ga8 (TM=V, Mo, W) were synthesised from the elements. Structure determinations of the isotypic compounds (cI104, space group image, image; Mo2Cu3Ga8: a=11.9171(10) Å, 613 refl., 23 param., image, image; W2Cu3Ga8: 11.9248(8) Å, 346 refl., 23 param., image, image; V2Cu3Ga8: 11.7861(14) Å, 374 refl., 24 param., image, image) showed a new cubic structure type which can be classified as an ordered defect variant of a bcc packing with image: [(TM)2(Cu)3(□)3][Ga8]. The coordination polyhedra of the transition metals consist of Ga8-cubes with 3 sides capped by Cu leading to coordination number 11. The arrangement of the TMGa8Cu3-polyhedra is in a way they form itself a 3-fold capped cube. All compositions were confirmed by EDX measurements.