Coupling of Epoxides to Pt^II‐Complexes with Carbon Dioxide and the Structure of a Cyclic Metallacarbonate

Abstract

Model complexes for postulated intermediates in the preparatively important catalytic coupling of CO2 and epoxides to give cyclic carbonates are provided by the compounds 1 ( = bpy, phen; R = H, Ph, CH2OPh). They are formed upon reaction of [PtMe2( )] with epoxides under CO2 atmosphere. In principle, CO2 in the air should be sufficient.

Selective Carbon–Carbon Bond Activation of Epoxides by a Bisphosphine Pt(0) Complex

“…On the other hand, the synthesis and detailed investigation of easily accessible and abundantly available 2-metallaoxetanes A for a broad variety of metals has been a continuous focus of active research, because inter alia they are supposed to be key intermediates in important oxygen-transfer reactions . In addition, less oxophilic metals are able to undergo insertion reactions of small molecules into their M-O bonds, resulting in ring expansion or epoxide functionalization reactions. , Not by direct C–C bond activation of epoxides, but by independent synthesis, Hoover and Stryker have synthesized the first and so far unique examples of 3-platinaoxetanes B , L 2 Pt­[(CH 2 ) 2 O] (L = PPh 3 , PMe 3 and L 2 = bis­(diphenylphosphino)­ethane, respectively). They are accessible via intramolecular dehydration of cis -bis­(hydroxymethyl) platinum precursor complexes. , These 3-oxaplatinacyclobutanes B are quite stable, and no insertions into their Pt–C-bonds are observed.…”

“…Among the large variety of nucleophiles and electrophiles (and radicals) which may be employed to harvest the synthetic potential of epoxides, transition metals have played an important role during the past few decades. Much attention has been paid to epoxide bond activation and ring-enlargement reactions at transition metal centers. A fascinating low-temperature C–H activation of ethylene oxide at Rh­(I) in solution was reported by Bergman et al, leading to an intermediate oxiranyl hydrido Rh­(III)-species.…”

Oxidative Addition Reactions of Organoplatinum(II) Complexes with Nitrogen-Donor Ligands

“…Ring strain can enhance the reactivity of certain bonds and facilitate the oxidative addition reaction. For example, the C−O bond of certain oxiranes and β-lactones is activated by ring strain to oxidatively add to diimine complexes of the type [PtMe 2 (NN)]. , Thus, β-propiolactone oxidatively adds to the platinum(II) center with overall second-order kinetics and Δ S ‡ = −129 to −151 J K -1 mol -1 , both consistent with a polar S N 2-type pathway (Scheme ) 17 …”

Organoplatinum(iv) tris-chelate complexes, each having a cyclic metallacarbonate ring: synthesis, characterization and kinetic studies of the formation

“…By the reaction of [PtMe 2 (NN)] (NN = 2,2Јbipyridine, bpy, or NN = 1,10-phenanthroline, phen), which bears an electron rich platinum() centre, with oxiranes and carbon dioxide, it has been possible to prepare a series of cyclic platinacarbonate complexes. 4,5 In this study, this cycloaddition reaction has been performed using [Pt{(CH 2 ) 4 }(NN)], 1, to prepare tris-chelate organoplatinum() complexes, each containing a cyclic metallacarbonate ring. These are important complexes, as the metallacycles are of considerable interest because of their possible role in catalysis, 6,7 and also organometallic tris-chelate complexes are not common.…”

“…Also, kinetics of formation of the tris-chelate organoplatinum() products are investigated and the results are compared with results of similar studies of the dimethyl analog. 4…”