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 )PtCl 2 ( 3 ) and (SbQ 2 Ph)PtCl 2 ( 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)-λ 3 -iodane (PhICl 2 ) 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.