A Synthetic Route to Alkyl−Pt^III Dinuclear Complexes from Olefins and Its Implication on the Olefin Oxidation Catalyzed by Amidate-Bridged Pt^III Dinuclear Complexes

Abstract

Amidate-bridged Pt III dinuclear complexes [Pt 2 (NH 3 ) 4 (Am) 2 (H 2 O) 2 ] 4+ (Am ) amidate ligand) catalyze oxidation of olefins in acidic aqueous solution. Linear olefins are oxidized to ketones, whereas cyclic olefins are oxidized to epoxides. GC-MS analysis of the oxidation products obtained from the reaction in H 2 18 O showed that the oxygen atoms in the products are exclusively from water, suggesting that the reaction mechanism is basically similar to that of the Wacker reaction. In accordance with this mechanism, pivalamidate-bridged Pt III complex [Pt III 2 (NH 3 ) 4 ((CH 3 ) 3 CCONH) 2 (H 2 O) 2 ] 4+ has been found to react with olefins to give alkyl complexes. Reactions with 4-penten-1-ol and ethylene glycol vinyl ether in acidic aqueous solution gave [Pt III 2 (NH 3 ) 4 ((CH 3 ) 3 CCONH) 2 (CH 2 CH(CH 2 ) 3 O)](NO 3 ) 3 ‚H 2 O (7) and [Pt III 2 (NH 3 ) 4 ((CH 3 ) 3 CCONH) 2 (CH 2 CHO)]-(NO 3 ) 3 ‚H 2 O (9), respectively. The two compounds have been structurally confirmed by X-ray diffraction analysis and 1 H, 13 C, and 195 Pt NMR spectroscopy. The 1 H NMR of 9 shows that both π-and σ-complexes exist in equilibrium in D 2 O, although the X-ray structure is close to the σ-complex. High electrophilicity of the R-carbon atoms of the compounds has been shown in the reactions with OH -. The above reactions with olefins can be a general route to prepare dimeric Pt III -alkyl complexes.

Mechanisms of the Axial Ligand Substitution Reactions of Dinuclear, Head‐to‐Head α‐Pyrrolidonato‐ and Pivalamidato‐Bridged cis‐Diammineplatinum(III) Complexes with Halide Ions

“…The formation of the HH monohalo complex (step 1) proceeds through two parallel paths: a simple substitution path (k 1 ) and a path (k 1 # ) accelerated by the trans-coordinated OH Ϫ . The formation of the HH dihalo complex from the aquahalo complex (step 2) proceeds through only a simple substitution path (k 2 ) for the reactions of the α-pyrrolidonato-and pivalamidato-bridged complexes with Cl Ϫ , and the mechanism is different from [18,19] Measurements: Ionic strength was maintained at 2.00  with perchloric acid and sodium perchlorate. All the sample solutions were prepared in doubly distilled water just before measurement.…”

Electrophilic Activation of Alkenes by Platinum(II): So Much More Than a Slow Version of Palladium(II)

“…Matsumoto and co-workers [88,89] reported that tetranuclear platinum blue complexes and dinuclear Pt …”

Kinetics and mechanisms of the axial ligand substitution reactions of platinum(III) binuclear complexes with halide ions

“…(2)) occur to the same or opposite axial sites of the Pt(III) dimer. By considering crystal structures on the related HH and HT dimers (Table 3), it is clearly indicated that the axial position of the Pt(N 2 O 2 ) in the HH complexes is always occupied by a ligand with a stronger trans influence [33,[36][37][38][39][40]. Furthermore, some of the HH pivalamidato-bridged organopaltinum(III) dimers, in which an alkenyl or a ketonyl group with much strong trans influence binds to the Pt(N 2 O 2 ) moiety, have no ligand at opposite Pt(N 4 ) axial site (Table 3) [23,34,[41][42][43].…”