A new mixed group 5 metal selenide, Nb1.41V0.59Se9

The new mixed-metallic phase, niobium vanadium nona-selenide, (Nb(2-x)V(x))Se(9) (0.18≤ x ≤ 0.59) is isostructural with monoclinic V(2)Se(9). The structure is composed of chains of bicapped trigonal-prismatic [MSe(8)] units. The metal (M) site is occupied by statistically disordered Nb [0.706 (5)] and V [0.294 (5)] atoms. Two trigonal prisms are linked by sharing a recta-ngular face composed of two Se(2) (2-) pairs. Through three edging and capping Se atoms, the chains are extended along [101]. The chain shows alternating short [2.8847 (7) Å] and long [3.7159 (7) Å] M-M distances. The structure shows a wide range of Se-Se inter-actions. In addition to the Se(2) (2-) pairs of the recta-ngular face, an inter-mediate Se⋯Se separation [2.6584 (5) Å] is found. The amount of each metal can vary, [(Nb(2-x)V(x))Se(9), 0.18 ≤ x ≤m 0.59] and they seem to form a random substitutional solid solution. The M-M distances increase gradually by increasing the amount of Nb atoms. The classical charge-balance of the compound can be described as [M(4+)](2)[Se(2) (2-)](2)[Se(5) (4-)].