A polymeric Mo polyselenide, K2Mo3Se18, and a large molecular cluster Mo polyselenide, K8Mo9Se40-4H2O, were synthesized by the hydrothermal method. The reaction of Mo, K2Se4, and H2O in a 1:1.5:22.2 ratio in a vacuum-sealed Pyrex tube at 135 °C for 3 days yielded black platelike crystals of K2Mo3Se18(I). The reaction of MoO3, K2Se2, and H2O in a 1:2:22.2 ratio under the same conditions as above yielded black chunky crystals of K8Mo9Se40-4H2O (II). Both compounds were obtained in ~20% yield. The structures were determined by single-crystal X-ray diffraction techniques. Crystal data for K2Mo3Se18: monoclinic P21Z = 2, a = 10.277 (6) Å, b = 12.66 (1) Å, c = 10.624 (8) Å, β = 116.82 (5)°, V = 1233 (2) Å3; 2θmax(Mo Kα) = 45°; number of data measured 1824, number of unique data 1608, number of data having Fo2> 3σ(Fo2) 1382, number of variables 207, number of atoms 23; µ = 267 cm-1; final R = 0.052 and Rw= 0.086. Crystal data for K8Mo9Se40-4H2O: triclinic PI, Z = 2, a = 10.312 (8) Å, b = 18.55 (3) Å, c = 18.57 (2) Å, α = 87.6 (1)°, β = 87.57 (7)°, γ = 84.0 (1)°, V = 3523 (8) Å3; 2θmax(Mo Kα) = 45°; number of data measured 9888, number of unique data 8638, number of data having Fo24σ(Fo2) 3592, number of variables 546, number of atoms 65; µ = 224 cm-1; final R = 0.092 and Rw = 0.108. I and II have rather complicated structures. I contains the [Mo3(Se)(Se2)3(Se3)(Se4)2]n2-polymeric anion which contains [Mo3Se7]4+clusters as building blocks. It has a zigzag chain structure which is formed by two parallel sets of face-to-face [MoMo3Se7]4+clusters cross-linked by Se42-ligands. The zigzag chains are then arranged side by side and interact through weak Se—Se contacts generated by a Se atom of a Se32-ligand of one chain and the triangular face of Se atoms from the three bridging Se22-ligands of a [Mo3Se7]4+cluster in another chain. [Mo, Se40]8contains three trinuclear [Mo3Se7]4+subclusters which are “glued” together by the two monoselenide ions. One monoselenide ion belongs to a [Mo3Se7]4+core being coordinated to three Mo atoms and at the same time interacting with the triangular face of three Se atoms of Se22-bridging ligands of another [Mo3Se7]4+subcluster. The other monoselenide ion interacts with six Se atoms of Se22-bridging ligands of two [Mo3Se7]4+subclusters. Two separate [Mo3Se7]4+clusters come in close contact (2.98 Å) in the solid state through two terminal Se22-ligands related by an inversion center.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry