Specific nonbonded interactions in the structures of M3X7 4+ and M3X4 4+ (M=Mo,W; X=O,S, Se) clusters

Specific nonbonded interactions (SNI) involving the chalcogens in the structures of (₃–X)(₂–X₂)₃M₃ ⁴⁺ and (₃–X)(₂–X)₃M₃ ⁴⁺ (M = Mo, W; X = 0, S, Se) clusters are examined. Interionic contacts significantly shorter than the sum of the van der Waals or ionic radii are fomd between the X atom of the X₂ ligands that occupy the axial position relative to the M₃ plane and the N, chalcogen, or halide of the counterion or identical ion. Centrosymmetric dimers involving the (₂-X₂) ligands are observed in the stmctures of several M₃X₄ ⁴⁺ derivatives. The X...X distance in these is also much less than the sum of the van der Waals radii. These SNI open occur in spite of the Coulombic repulsion of similarly charged species. The SNZ are classified using existing data. They play a definite role in forming of the crystal structure.Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 2, pp. 150–167, March–April, 1993.