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Reactivity of Quinoline-8-carbaldehyde toward Platina-β-diketone and Acetyl(amine)platinum(II) Complexes. Formation of Acyl(hydroxyalkyl)platinum(IV)

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posted on 10.02.2014, 00:00 by Itziar Zumeta, Tim Kluge, Claudio Mendicute-Fierro, Cristoph Wagner, Lourdes Ibarlucea, Tobias Rüffer, Virginia San Nacianceno, Dirk Steinborn, María A. Garralda
The reaction of the platina-β-diketone [Pt2{(COMe)2H}2(μ-Cl)2] (1) with quinoline-8-carbaldehyde (C9H6NCHO) in MeOH/H2O (Pt/C9H6NCHO = 1/2) leads to the cleavage of the chloride bridges in 1 with acetaldehyde displacement and to the formation of the acetylacyl­(hydroxyalkyl)­platinum­(IV) complex [Pt­(COMe)­Cl­(C9H6NCO-κNC)­(C9H6NCHOH-κNC)] (3) as a single diastereomer (OC-6-46). Water-assisted activation of the OC–H bond of one aldehyde and H transfer to the oxygen atom of the second aldehyde occurs. In the presence of sodium methoxide, dehydrochlorination of the platinum starting material affords the dinuclear [Pt2(C9H6NCO-κNC)2(μ-COMe)2] (4) with acetyl bridges in a head-to-tail fashion. Pyridine or tetrahydrofuran fail to cleave the acetyl bridges, which are readily cleaved by triphenylphosphane to afford the mononuclear [Pt­(C9H6NCO-κNC)­(COMe)­(PPh3)] (5) with the two acyl groups in cis positions. The reaction of the diacetylbis­(amine)­platinum­(II) complexes [Pt­(COMe)2(NH2R)2] (R = CH2Ph (2a), Et (2b)) with quinoline-8-carbaldehyde produced the Schiff base products [Pt­(COMe)2(C9H6NCHNR-κNN′)] (R = CH2Ph (6a), Et (6b)). The complexes have been fully characterized, and X-ray diffraction structures of 3 and 4 are reported.