On the Reactivity of Platina-β-diketones - Synthesis and Characterization of Acylplatinum(II) Complexes

Abstract

The platina‐β‐diketones [Pt2{(COR)2H}2(μ‐Cl)2] (1, R = Me a, Et b) react with phosphines L in a molar ratio of 1 : 4 through cleavage of acetaldehyde to give acylplatinum(II) complexes trans‐[Pt(COR)Cl(L)2] (2) (R/L = Me/P(p‐FC6H4)3 a, Me/P(p‐CH2=CHC6H4)Ph2 b, Me/P(n‐Bu)3 c, Et/P(p‐MeOC6H4)3 d). 1 a reacts with Ph2As(CH2)2PPh2 (dadpe) in a molar ratio of 1 : 2 through cleavage of acetaldehyde yielding [Pt(COMe)Cl(dadpe)] (3 a) (configuration index: SP‐4‐4) and [Pt(COMe)Cl(dadpe)] (configuration index: SP‐4‐2) (3 b) in a ratio of about 9 : 1. All acyl complexes were characterized by 1H, 13C and 31P NMR spectroscopy. The molecular structures of 2 a and 3 a were determined by single‐crystal X‐ray diffraction. The geometries at the platinum centers are close to square planar. In both complexes the plane of the acyl ligand is nearly perpendicular to the plane of the complex (88(2)° 2 a, 81.2(5)° 3 a).

Mechanistic Studies on Platinum(II) Catalyzed Hydroarylation of Alkynes

“…The 1 H– 1 H coupling constant J of 17 Hz suggests an E configuration of the vinylic protons. An unambiguous assignment of the signals for H α and H β could be made by a 1 H, 13 C COSY experiment (S1, Supporting Information) and by comparison with respective NMR spectra reported for structurally related complexes. , …”

On the Reactivity of the Platina‐β‐diketone [Pt2{(COMe)2H}2(μ‐Cl)2] Towards Ph2PCH2CH2CH2SOxPh (x = 0, 2)

“…Reactions of the dinuclear platina-β-diketone [Pt 2 {(COMe) 2 H} 2 (μ-Cl) 2 ] (1) with the γ-phosphinofunctionalized propyl phenyl sulfide (Ph 2 PCH 2 CH 2 CH 2 SPh, 2) and sulfone (Ph 2 PCH 2 CH 2 CH 2 SO 2 Ph, 3) lead via an unseen platinum(IV) intermediate of type A with reductive elimination of acetaldehyde [4,19] (detected 1 H NMR spectroscopically) to the formation of type B acetyl(chlorido) platinum(II) complexes (4, 5) (Scheme 1). In complex 4, ligand 2 acts as a chelating P ∧ S donor; analogous reactions were found with other bidentate P ∧ P [4] or N ∧ S [7] donors.…”