A new compound derived from Magnus' green salt: solid state structure and evidence for platinum chains in solution

Abstract

The complex [Pt(NH₂Eh)₄][PtCl₄], where Eh = 2-ethylhexyl, was synthesized and analyzed using various methods. The results imply that [Pt(NH₂Eh)₄][PtCl₄] forms supramolecular structures composed of chains of platinum atoms not only in the solid state but, most remarkably, also in solution, as indicated by membrane osmometry and viscosimetry. At 37°C in toluene, the chains are present in a worm-like structure and contain ca. 750 platinum atoms on average. The solid state properties of [Pt(NH₂Eh)₄][PtCl₄] are distinct from those of related compounds with linear 1-aminoalkanes. In particular, [Pt(NH₂Eh)₄][PtCl₄] is cryochromic and amorphous. The 2-ethylhexyl chains obviously prevent side chain crystallization and, as a consequence, electrostatic interactions between the [Pt(NH₂Eh)₄]²⁺ and [PtCl₄]²⁻ units seem to dominate the structure formation of [Pt(NH₂Eh)₄][PtCl₄].