Structural and Oxidation State Alternatives in Platinum and Palladium Complexes of a Redox-Active Amidinato Ligand.

ABSTRACT: Reaction of [Pt(DMSO)₂ Cl₂ ] or [Pd(MeCN)₂ Cl₂ ] with the electron-rich LH=N,N'-bis(4-dimethylaminophenyl)ethanimidamide yielded mononuclear [PtL₂ ] (1) but dinuclear [Pd₂ L₄ ] (2), a paddle-wheel complex. The neutral compounds were characterized through experiments (crystal structures, electrochemistry, UV-vis-NIR spectroscopy, magnetic resonance) and TD-DFT calculations as metal(II) species with noninnocent ligands L^- . The reversibly accessible cations [PtL₂ ]⁺ and [Pd₂ L₄ ]⁺ were also studied, the latter as [Pd₂ L₄ ][B{3,5-(CF₃ )₂ C₆ H₃ }₄ ] single crystals. Experimental and computational investigations were directed at the elucidation of the electronic structures, establishing the correct oxidation states within the alternatives [Pt^II (L^- )₂ ] or [Pt^. (L )₂ ], [Pt^II (L^0.5- )₂ ]⁺ or [Pt^III (L^- )₂ ]⁺ , [(Pd^II )₂ (μ-L^- )₄ ] or [(Pd^1.5 )₂ (μ-L^0.75- )₄ ], and [(Pd^2.5 )₂ (μ-L^- )₄ ]⁺ or [(Pd^II )₂ (μ-L^0.75- )₄ ]⁺ . In each case, the first alternative was shown to be most appropriate. Remarkable results include the preference of platinum for mononuclear planar [PtL₂ ] with an N-Pt-N bite angle of 62.8(2)° in contrast to [Pd₂ L₄ ], and the dimetal (Pd₂ ⁴⁺ →Pd₂ ⁵⁺ ) instead of ligand (L^- →L ) oxidation of the dinuclear palladium compound.

SUBMITTER: Ehret F 

PROVIDER: S-EPMC7986709 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature