Synthesis and redox properties of mono-, di- and tri-metallic platinum-ethynyl complexes based on the trans-Pt(C6H4N{C6H4OCH3-4}2)(CCR)(PPh3)2 motif

The Pt-halide complex trans-PtI{C6H4NAr2}(PPh3)2 (Ar = C6H4OMe-4, 3) was prepared by oxidative addition of N(C6H4I)Ar2 (2) to Pt(PPh3)4. Reactions of trans-PtI{C6H4NAr2}(PPh3)2 (3) with 1-alkynes under CuI catalysed dehydrohalogenation conditions allows the preparation of a range of platinum ethynyl compounds containing up to four redox-active triarylamine centres. The compounds trans-Pt(CCAr)(C6H4NAr2)(PPh3)2 (4a), trans-Pt(CCC6H4NAr2)(C6H4NAr2)(PPh3)2 (4b), {trans-Pt(C6H4NAr2)(PPh3)2}2(μ-CC-1,4-C6H4CC) (5) and N{C6H4CCPt(C6H4NAr2)(PPh3)2}3 (6) undergo a single electrochemical event for each chemically distinct type of triarylamine in the molecular backbone. The complete reversibility of the larger systems means that they can be used for charge storage materials capable of releasing up to four electrons. A combination of electrochemical, spectroelectrochemical and quantum chemical analyses reveal weak electronic coupling between the amine moieties in the redox products derived from one-electron oxidation.

The compounds trans-Pt(CCAr)(C6H4NAr2)(PPh3)2 (4a), trans-Pt(CCC6H4NAr2)(C6H4NAr2)(PPh3)2 (4b), {trans-Pt(C6H4NAr2)(PPh3)2}2(μ-CC-1,4-C6H4CC) (5) and N{C6H4CCPt(C6H4NAr2)(PPh3)2}3 (6) have been studied using a combination of electrochemical, spectroelectrochemical and quantum chemical analyses, which reveal weak electronic coupling between the amine moieties in the formally organic mixed-valence complexes formed on one-electron oxidation.Figure optionsDownload as PowerPoint slide