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On the Reactivity of Platina-β-diketone and Acetylplatinum(II) Complexes toward 2-(Diphenylphosphanyl)benzaldehyde and Its Dioxolane Derivative



The dinuclear platina-β-diketone [Pt2{(COMe)2H}2(μ-Cl)2] (1) reacts with four and two equivalents of 2-[2-(diphenylphosphanyl)phenyl]-1,3-dioxolane (L1) to yield [Pt(COMe)Cl(PPh2{o-C6H4CH(O2C2H4)}-κP)2] (3) and [Pt(COMe)Cl(PPh2{o-C6H4CH(O2C2H4)}-κPO)] (4), respectively. The weak Pt–O bond in 4 can be easily broken up by stronger donors. Thus, complex 4 reacts with PPh3 to yield [Pt(COMe)Cl(PPh3)(PPh2{o-C6H4CH(O2C2H4)}-κP)] (5) and [Pt(COMe)Cl(PPh3)2] (6) as well as with L1 to yield 3. Diacetylbis(amine)platinum(II) complexes cis-[Pt(COMe)2(NH2R)2] (R = Bn, 2a; R = Et, 2b; Bn = benzyl) react with L1 with the substitution of one amine ligand to yield [Pt(COMe)2(NH2R)(PPh2{o-C6H4CH(O2C2H4)}-κP)] (R = Bn, 7a; R = Et, 7b). The unprotected 2-(diphenylphosphanyl)benzaldehyde (L2) reacts with the platina-β-diketone 1 by oxidative C–H addition followed by reductive elimination of acetaldehyde to form [PtCl{PPh2(o-C6H4CO)-κPC}{PPh2(o-C6H4CHO)-κP}] (8). On the other hand, the reactions of diacetylbis(amine)platinum(II) complexes 2a/b and L2 proceeded with Schiff base formation and, thus, yielded complexes bearing hemiaminal–phosphane ligands, [Pt(COMe)2(PPh2{o-C6H4CH(OH)(NHR)}-κPN)] (R = Bn, 9a; R = Et, 9b), and imine–phosphane ligands, [Pt(COMe)2{PPh2(o-C6H4CH=NR)-κPN}] (R = Bn, 10a; R = Et, 10b). The identities of all platinum complexes were unambiguously proved by microanalyses, high-resolution mass spectrometric investigations, NMR (1H, 13C, 31P, 195Pt) and IR spectroscopy, and single-crystal X-ray diffraction analyses (for 4, 9a). The differences in the reactivity of the aldehyde–phosphane L2 and its acetal-protected derivative L1 are discussed.