Synthesis and structural, electrochemical and NMR analysis of the [{Pt(PEt3)2}2Te2]n series (n= 0,2 +) and the bicapped triplatinum [{Pt(PEt3)2}3(µ3-Te)2]2+ dication: Te–Te bond formation in a cyclo-Pt2Te2 core upon a chemically reversible two-electron oxidation

Abstract

Room-temperature reactions of three [Pt₃(CO)₆]_n^2– dianions (n= 3, 4, 5) with TePEt₃ in tetrahydrofuran (containing [AsPh₄]⁺Cl^–) give rise to the 32-electron [{Pt(PEt₃)₂}₂(µ₂-Te)₂]1, the 30-electron [{Pt(PEt₃)₂}₂(µ₂-Te₂)]²⁺ dication 2 and the 48-electron [{Pt(PEt₃)₂}₃(µ₃-Te)₂]²⁺ dication 3 which were characterized by X-ray diffraction, electrochemical and multinuclear (¹H, ¹³C, ¹⁹F, ³¹P, ¹⁹⁵Pt) NMR measurements; a chemical two-electron oxidation of 1, which has a planar cyclo-Pt₂Te₂ core, quantitatively produces 2 with a highly bent bicyclo-Pt₂Te₂ core due to the formation of an electron-pair Te–Te bond (which can be reversibly cleaved upon chemical reduction to reconvert 2 into 1).