Synthesis and structure of phases containing [Ni3P3S12]3− crown-shaped trimers

Abstract

The exfoliation process of one-dimensional KNiPS₄ showed that the breaking of ¹/_∞[NiPS₄]⁻ chains in polar solvent was followed by the formation of cyclic [Ni₃P₃S₁₂]³⁻ trianions. From DMF–KNiPS₄ solutions, metathesis experiments were successfully carried out, but, up to now, K⁺ had only been exchanged by bigger isotropic organic cations such as PPh₄⁺, (CH₃)₄N⁺ and (C₂H₅)₄N⁺. After recrystallization, each metathesis compound presents the cyclic [Ni₃P₃S₁₂]³⁻ trianion. An exchange by anisotropic cations is possible by adding a cryptand molecule that fits the size of K⁺. Following this procedure, three new nickel thiophosphate complexes have been synthesized: [Ni₃P₃S₁₂][K-(222-cryptand)]₃ (I), [Ni₃P₃S₁₂][K(222-cryptand)]₂[C₉N₁H₂₂] (II) and [Ni₃P₃S₁₂][CH₃(CH₂)₁₁N(CH₃)₃]₃ (III). The structures of I and II have been fully determined from single crystal X-ray diffraction analysis. They show the occurrence of the [Ni₃P₃S₁₂]³⁻ trimer within the solid. I and II crystallize in the P2₁2₁2₁ space group. ³¹P solid state NMR experiments hint at the presence of polyanions in III, maybe trianionic in nature.