Derivatives of Magnus’ Green Salt

Abstract

Magnus’ green salt is a quasi-one-dimensional compound of composition [Pt(NH3)4][PtCl4] comprising linear arrays of platinum(II) ions. It is essentially insoluble in water and organic solvents and therefore difficult to process, which limits its use. Recently, soluble and thus processible derivatives of Magnus’ green salt have been synthesised by substituting the ammonia by linear and branched aminoalkanes. The Pt-Pt distances and the properties of these Magnus’ salt derivatives depend on the detailed structure of the aminoalkane. In particular, in compounds with branched aminoalkanes weak but noteworthy interactions arise between adjacent platinum atoms, as is evident from their colour, their electrical conductivity, and their UV and IR spectra. Compounds with optically active branched aminoalkanes exhibit circular dichroism with a bisignate Cotton effect and unusually high absolute values for the chiral anisotropy factors. The complex [Pt(NH2dmoc)4][PtCl4] with dmoc designating (S)-3,7-dimethyloctyl is of particular importance since its colour and electrical conductivity strongly resemble those of Magnus’ green salt. Films of [Pt(NH2dmoc)4][PtCl4] can function as an active semiconducting layer in field effect transistors. Remarkably, such devices have superior stability in air and water to unprotected field effect transistors fabricated with typical organic polymers. Hence, Magnus’ salt derivatives might find use in components of mass-produced “plastic electronics”.