Reactivity of the dinuclear platina-β-diketone [Pt2{(COMe)2H}2(μ-Cl)2] towards chelating ligands – Bridge cleavage versus formation of acetyl(chloro)platinum(II) complexes

The dinuclear platina-β-diketone [Pt2{(COMe)2H}2(μ-Cl)2] (1) was found to react with 2-(ROCH2)C5H4N (R = Me, 2a; H, 2b) yielding a cationic mononuclear platina-β-diketone [Pt{(COMe)2H}{2-(MeOCH2)C5H4N}]Cl (3) and an acetyl(chloro)platinum(II) complex [Pt(COMe)Cl{2-(HOCH2)C5H4N}] (4), respectively. The reaction of 1 with 8-(methylthio)quinoline (5) resulted in the formation of [Pt(COMe)Cl{8-(MeS)C9H6N}] (6). The identities of all complexes were established by microanalysis, 1H, and 13C NMR spectroscopy. Single-crystal X-ray diffraction analysis showed 6 to be square–planar platinum(II) complex with N and C atoms as well as Cl and S atoms in mutually trans positions (configuration index: SP-4-2). In accordance with this, quantum chemical calculations on the DFT level of theory revealed a higher stability of complex 6 having a SP-4-2 configuration vs. the analogous complex in SP-4-3 configuration. The distinctly different reactivity of 1 with 2a on the one hand and with 2b and 5 on the other is discussed in terms of the HSAB concept and a deprotonation/reprotonation reaction.