Two polymorphs of tetraethylammonium [hydrogen tris(3,5-dimethylpyrazolyl)borato]di-μ₂-sulfido-disulfido(η²-tetrasulfido)ditungsten(V) withZ′ = 1 and 2

Abstract

Two polymorphs of the title compound, (C(8)H(20)N)[W(2)S(4)(S(4))(C(15)H(22)BN(6))], have been obtained unexpectedly by attempted recrystallization of a mixed-metal-sulfur cluster complex from different solvents. The dinuclear complex anion contains W(V) in two different coordination environments, one of them distorted octahedral with a tris(pyrazolyl)borate anion, a terminal sulfide and two bridging sulfide ligands, the other distorted square-pyramidal with a terminal sulfide, two bridging sulfide and a chelating tetrasulfide ligand. The three independent anions in the two polymorphs have essentially the same geometry. The central W(2)S(2) ring is a slightly folded rhombus with acute angles at the S atoms, and the WS(4) chelate ring is an envelope with one noncoordinating S atom as the flap. The second polymorph, with Z' = 2 and pseudo-inversion symmetry relating the anions of the asymmetric unit, also displays pseudo-translation features in its layer structure, and all examined crystals were found to be twinned, possibly as a consequence of this structural feature.

Polymorphic behavior of an organic compound

“…Different polymorphs were obtained from different crystallization procedures which lead to two polymorphs precipitating similarly in the same crystallization experiment. New polymorphs were formed by different crystallization solvents, temperatures or rates of crystallization [7,8]. The organic molecules were crystallized by hydrogen bonding which is a most important discriminating cohesive force [9].…”