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; whil e the Pt-Pt distances were equal in [Pt(NH2Et)(4)][Pt(mnt)(2)] (3.96 Angstr om), surprisingly, two different intermetallic. spacings (3.86 and 4.01 Ang strom) were observed in [Pt(NH(2)Oc)(4)][Pt(mnt)(2)]. The Pt-Pt distances i n the [Pt(NH2R)(4)][Pt(mnt)(2)] compounds are large compared to those in th e typical Magnus-salt-type complexes (3.15-3.62 Angstrom). An uncommon, rev ersible solid-state phase transition was detected for [Pt(NH(2)Oc)(4)][Pt(m nt)(2)] at 70 degreesC, which might be related to a change in the packing o f the octyl chains. The platinum stacks decayed when in solution, yielding predominantly ion pairs. The UV-Vis absorption spectra of such solutions we re 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 r ights reserved.