The M2Cr30P19 Compounds (M = Zr, U): A New Defective Structure Type in the Transition Metal Pnictides Family with Metal/Nonmetal Ratio Close To 2

The ternary compounds M2Cr30P19 (M = Zr, U) have been synthesized by the tin flux method. They have isotypic hexagonal crystal structures, space group P6 with one formula per unit cell. The X-ray structures of both compounds were refined from three-dimensional single-crystal intensity data to final R values of 0.029 (Zr2Cr30P19) and 0.049 (U2Cr30P19) for 567 (I > 3σ(I)) and 974 (I > 4σ(I)) reflections, respectively. The resulting structure is of a new type and belongs to the large structural family with the general formula M∼2X (M = transition metal; X = As, P, Sb, Bi … ). The structural relationships with the defective Yb6Co30P19 compound are discussed in terms of metal vacancies and of coordination polyhedra. The metallic behavior of the new phosphides is demonstrated.