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

Abstract

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)}‐κP,κO)] (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)‐κP,κC}{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)}‐κP,κN)] (R = Bn, 9a; R = Et, 9b), and imine–phosphane ligands, [Pt(COMe)2{PPh2(o‐C6H4CH=NR)‐κP,κN}] (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.

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

“…At variance with the reaction of 2 with o -(diphenylphosphino)benzaldehyde, where the imine–phosphane complexes and the intermediate hemiaminal–phosphane complexes could be isolated and characterized, in the present case intermediate hemiaminal derivatives could be neither obtained nor detected by NMR, thus showing that the condensation reaction is much faster when using quinoline-8-carbaldehyde than when using the more flexible o -(diphenylphosphino)benzaldehyde. Complexes 6a , b could both be isolated as a brown or red powder in a yield of 35–85%.…”

“…16 Furthermore, oxidative addition of halogens and halides to diacetylplatinum-(II) results in the requisite platinum(IV) complexes. 17 19 We report now on the reaction of 1 with quinoline-8-carbaldehyde leading to unprecedented acyl(hydroxyalkyl)platinum(IV) derivatives or to dinuclear acetyl-bridged platinum(II) complexes, depending on the reaction conditions. The reaction of C 9 H 6 NCHO with 2 is also reported.…”

“…In the presence of a base, a reductive HCl elimination on [PtHCl(COMe) 2 (LL)] can be enforced to selectively yield the diacetylplatinum(II) complexes [Pt(COMe) 2 (LL)] . Recently we have reported that PPh 2 ( o -C 6 H 4 CHO) reacts with 1 to produce [PtCl{PPh 2 ( o -C 6 H 4 CO)-κ P ,κ C }{PPh 2 ( o -C 6 H 4 CHO)-κ P }], while in the reactions with the diacetylbis(amine)platinum(II) complexes [Pt(COMe) 2 (NH 2 R) 2 ] ( 2 ), the Schiff base reaction products [Pt(COMe) 2 {PPh 2 ( o -C 6 H 4 CHNR)-κ P ,κ N }] and the intermediate hemiaminal-containing species [Pt(COMe) 2 (PPh 2 { o -C 6 H 4 CH(OH)(NHR)}-κ P ,κ N )] are obtained, depending on the reaction conditions . We report now on the reaction of 1 with quinoline-8-carbaldehyde leading to unprecedented acyl(hydroxyalkyl)platinum(IV) derivatives or to dinuclear acetyl-bridged platinum(II) complexes, depending on the reaction conditions.…”