Reactivity of diacetylplatinum(II) complexes: oxidative addition of alkyl halides and crystal structures of acetyl platinum(IV) complexes

Abstract

Diacetylplatinum(II) complexes [Pt(COMe) 2 -(N^N)] (N^N = bpy, 3a; 4,4 0 -t-Bu 2 -bpy, 3b) were found to undergo oxidative addition reactions with organyl halides. The reaction of 3a with methyl iodide and propargyl bromide led to the formation of the cis addition products (OC-6-34)-[Pt(COMe) 2 (R)X(bpy)] (R = Me, X = I, 4a; CH 2 C:CH, X = Br, 4k). Analogous reactions of 3a with ethyl iodide, benzyl bromide, and substituted benzyl bromides, 3-(bromomethyl)pyridine, 2-(bromomethyl)thiophene, allyl bromide, and cyclohex-2-enyl bromide led to exclusive formation of the trans addition products (OC-6-43)-[Pt(COMe) 2 (R)X(bpy)] (X = I, R = Et, 4b; X = Br, R = CH 2 C 6 H 5 , 4c; CH 2 C 6 H 4 (o-Br), 4d; CH 2 C 6 H 4 (p-COOH), 4e; CH 2 -3-py (3-pyridylmethyl), 4f; CH 2 -2-tp (2-thiophenylmethyl), 4g; CH 2 CH=CH 2 , 4h; c-hex-2-enyl (cyclohex-2-enyl), 4i). All complexes 4 were characterized by microanalysis, 1 H and 13 C NMR and IR spectroscopy. Additionally, complexes 4a, 4f, and 4g were characterized by single-crystal X-ray diffraction analyses. Reactions of 3a and 3b with o-, m-and p-bis(bromomethyl)benzene, respectively, led to the formation of dinuclear platinum(IV) complexes [{Pt(COMe) 2 Br(N^N)} 2 {l-(CH 2 ) 2 C 6 H 4 }] (5). These complexes were characterized by microanalysis, IR spectroscopy, and depending on their solubility by 1 H and 13 C NMR spectroscopy, too. A single-crystal X-ray diffraction analysis of complex [{Pt(COMe) 2 Br(bpy)} 2 {l-m-(CH 2 ) 2 C 6 H 4 }] (5b) confirmed its dinuclear composition. The solid-state structures of 4a, 4f, 4g, and 5b are discussed in terms of C-HÁÁÁO and O-HÁÁÁO hydrogen bonds as well as p-p stacking between aromatic rings.

Synthesis, Characterization, and Reactivity of Diacetylplatinum(II) and -platinum(IV) Complexes Bearing κ2- and κ3-Coordinated Scorpionate Ligands

“…The selective formation of diacetylplatinum(II) complexes of type C can be induced by the addition of bases to complexes A . In summary, reactions of the platina-β-diketone 1 toward various bidentate nitrogen donor ligands and also reactions of the resulting type C diacetylplatinum(II) complexes with reagents that enable oxidative addition reactions such as alkyl halides or halogens are well investigated . In contrast, the reaction of bis(2-picolyl)amine with [Pt 2 {(COMe) 2 H} 2 (μ-Cl) 2 ] ( 1 ) yielding a hydridoplatinum(IV) complex is the only example of an investigation on the reactivity of platina-β-diketones toward tridentate nitrogen donor ligands …”

Bis(diphenylphosphino)acetylene as bifunctional ligand in cycloplatinated complexes: Synthesis, characterization, crystal structures and mechanism of MeI oxidative addition

“…The related two-step reactions of complexes 1 and 2 with MeI were investigated by UVevis spectrophotometry; the reaction of complex 1 with MeI was also monitored by 31 P NMR spectroscopy. On the basis of the results, both steps of MeI oxidative addition proceed by the classical S N 2 type mechanism [70,71], as shown in Scheme 3, with large negative DS z values. In the first step, the electron rich platinum center of the Pt(II)ePt(II) starting complex 1 attacks the methyl carbon of MeI to form the intermediate B which is suggested to be a Pt(II)ePt(IV) complex.…”

Oxidative Addition of Propargyl Halides, Chloroacetonitrile, and Ethyl Chloroacetate to a Dimethylplatinum(II) Complex: Kinetic and DFT Studies

“…[M]CHCCH 2 . The related chemistry is of importance, as it may help in understanding the more complex structures. − As mentioned by Wojcicki, although the standard enthalpies of formation of MeCCH and CH 2 CCH 2 reflect a slightly higher stability of the propargyl species, a stronger metal–allenyl bond in comparison to a metal–propargyl bond favors the allenyl tautomer . Typically, two pathways have generally been considered for the oxidative addition reaction of propargyl halides, including 1,3-hydrogen and 1,3-metal (involving η 3 -allenyl and propargyl intermediates) migration.…”