Crystal structure of bis(tetramethylammonium) trismolybdenumtrideca sulfide, [N(CH3)4]2Mo3S13

Source of material: Single crystals of [N(CH3>4]2Mo3Si3 were obtained in a hydrothermal reaction of M0O3 with elemental sulfur, Na3SbS4 9H2O and tetramethylammoniumchloride (molar ratio = 1:5:2:1 ) in a 0.2 mol aqueous ammonia solution within 6 days. The reaction product consists of dark red hexagonal prisms up to 5 mm long. The cluster M03X13 (X=S, Se) is found in different compounds as isolated (see refs. 1, 2, 3) or interlinked species (see refs. 4, 5). It is build up from a molybdenum triangle held together by an apical chalcogen atom and six dichalcogen ligands. Three of them are bridging and three are terminal ligands (see Fig. 1, Mo-Mo 2.733(2) Â,Mo-S(l) 2.497(2) Â, Mo-S(2) 2.368(3) Â, Mo-S(3) 2.426(2) Â, Mo-S(4) 2.417(3) Â, Mo-S(5) 2.474(3) Â, S(l)-S(3) 2.022(4) Â, S(4)-S(5) 2.082(4) Â). In the tide compound as well as in the isotypic selenide [N(CH3)4]2Mo3Sei3 (see ref. 6), the apical chalcogen atom shows weak interaction to three of the chalcogen atoms from the bridging X2 (X=S, Se) ligands of the neighboured cluster, forming columnar stacks along the c-axis (see Fig. 2). The interaction seems to be less pronounced than in the seien compound as indicated by the nearest intercluster S -S distances of 3.130 Â compared to 3.174 Â for the Se-Se distance. We note that a shorter intercluster S—S distance type of 3.026 Â was reported for (NH4)2Mo3Si3 · H2O (see réf. 1). In addition the shortest intracluster S—S distances from the apical sulfur atom to the bridging S2 groups increases slightly from 3.281 Â (mean value) in the ammonium compound to 3.307 Â in the title compound whereas the distance to the terminal S2 groups decreases from 3.504 Â to 3.467 Â. Fig. 2. Arrangement of the M03S13 clusters along the c axis. The broken lines indicate the weak S-S interaction (3.130 Â).