Synthesis of Quinoline-Based Pt-Sb Complexes with L- or Z-Type Interaction: Ligand-Controlled Redox via Anion Transfer

A series of Pt-Sb complexes with two or three L-type quinoline side arms were prepared and studied. Two ligands, tri(8-quinolinyl)stibane (SbQ(3), Q = 8-quinolinyl, 1) and 8,8 '-(phenylstibanediyl)diquinoline (SbQ(2)Ph, 2), were used to synthesize the Pt-II-Sb-III complexes (SbQ(3))PtCl2 (3) and (SbQ(2)Ph)PtCl2 (4). Chloride abstraction with AgOAc provided the bis-acetate complexes (SbQ(3))Pt(OAc)(2) (5) and (SbQ(2)Ph)Pt(OAc)(2) (6). To better understand the electronic effects of the Sb moiety, analogous bis-chloride complexes were oxidized to an overall formal oxidation state of +7 (i.e., Pt + Sb formal oxidation states = 7) using dichloro(phenyl)-lambda(3)-iodane (PhICl2) and 3,4,5,6-tetrachloro-1,2-dibenzoquinone (o-chloranil) as two-electron oxidants. Depending on the oxidant, different conformational changes occur within the coordination sphere of Pt as confirmed by single-crystal X-ray diffraction and NMR spectroscopy. In addition, the nature of Pt-Sb interactions was evaluated via molecular and localized orbital calculations.