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

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-κN,κC)­(C9H6NCHOH-κN,κC)] (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-κN,κC)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-κN,κC)­(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-κN,κN′)] (R = CH2Ph (6a), Et
(6b)). The complexes have been fully characterized, and
X-ray diffraction structures of 3 and 4 are
reported.