Synthesis, crystal structures and properties of quasi-one-dimensional platinum compounds

Quasi-one-dimensional complexes of the type [Pt(NH2R)(4)][Pt(mnt)(2)] where mnt designates maleodinitriledithiolate and R an ethyl (Et) or octyl (Oc) group, were synthesized and characterized. Single-crystal X-ray diffraction revealed that both compounds crystallized in the triclinic. space group P1. The platinum atoms were arranged in linear arrays in both compounds; while the Pt-Pt distances were equal in [Pt(NH2Et)(4)][Pt(mnt)(2)] (3.96 Angstrom), surprisingly, two different intermetallic. spacings (3.86 and 4.01 Angstrom) were observed in [Pt(NH(2)Oc)(4)][Pt(mnt)(2)]. The Pt-Pt distances in the [Pt(NH2R)(4)][Pt(mnt)(2)] compounds are large compared to those in the typical Magnus-salt-type complexes (3.15-3.62 Angstrom). An uncommon, reversible solid-state phase transition was detected for [Pt(NH(2)Oc)(4)][Pt(mnt)(2)] at 70 degreesC, which might be related to a change in the packing of the octyl chains. The platinum stacks decayed when in solution, yielding predominantly ion pairs. The UV-Vis absorption spectra of such solutions were dominated by characteristics associated with [Pt(mnt)(2)](2-) units, and UV emission maxima were found at 345 and 363 mn upon excitation with light of wavelengths between 250 and 340 mn. (C) 2001 Elsevier Science B.V. AR rights reserved.