From Vauquelin's and Magnus' salts to gels, uniaxially oriented films, andfibers: Synthesis, characterization, and properties of tetrakis(1-aminoalkane)metal(II) tetrachlorometalates(II)

Complexes of the type [Pt(NH2R)(4)][PtCl4] with R = (CH2)(n)CH3, where n is 3, 6, 7, 8, 9, 11, or 13, were synthesized and characterized with various methods (e.g., IR spectroscopy, SAXS, XPS, NEXAFS, TEM, DSC, and TGA). For comparison, the classical Magnus' green and pink salt (where R = H) were al so prepared. The designated alkyl-substituted platinum compounds are pink, but their structure seems to be related rather with Magnus' green than with the pink salt. However, the Pt-Pt distance in the pink alkyl-substituted c ompounds is most likely larger than in Magnus' green salt. This result is i n agreement with the low electrical conductivity (<10(-10) S/cm) in the alk yl-substituted complexes. Because the Pt-Pt interactions in the [Pt(NH2R)(4 )][PtCl4] compounds are presumably weak, these substances may be regarded a s self-assembled supramolecular structures. Nonetheless, the prepared compl exes show some characteristics of rigid-rod polymers with flexible side cha ins; for example, they are insoluble when the alkyl chains are short but be come soluble for longer alkyl chains, and they are able to form two-dimensi onal hexagonal or sheet structures. The complexes melt under decomposition above 100 degrees C. The soluble [Pt(NH2R)(4)][PtCl4] complexes form gels w ith fibrillar structures at temperature ranges that depend on the length of R. Films and fibers with uniaxially oriented fibrils were prepared from ge ls by drawing and electrostatic spinning. The mixed-metal complexes [Pd(NH2 R)(4)][PtCl4] and [Pt(NH2R)(4)][PdCl4] (R = octyl) were also synthesized. T he chemical and physical properties of the compounds with palladium differe d significantly from those of [Pt(NH2R)(4)][PtCl4]. In particular, one of t hese complexes is insoluble, whereas the other one decomposes relatively qu ickly in solution.