The First Class of Square-Planar Platinum(II) Complexes Containing Electron-Poor Alkenes. Rare Insertion of an Alkene into a Pt−Alkyl Bond^†

The first class of square-planar Pt(II) complexes bearing electron-poor alkenes, i.e., [PtMe(N,N-chelate)(η2-CH2CHCOR)]BF4 (R = H, NMe2, Me, OMe), is described. By using N,N ligands with suitable steric properties, it was possible to inhibit olefin dynamic processes in solution, thus allowing a thorough characterization of the complexes. Insertion of methyl acrylate into the Pt−Me bond provides a rare example of migratory insertion of an alkene into a Pt−alkyl bond

[PtR(η²-olefin)(N-N)]⁺ Complexes Containing the Olefin and the Alkyl Ligand in a <i>cis</i> Arrangement. Preparation, Structural Characterization, and Olefin Stereochemistry

Cationic Pt(II) complexes containing an alkyl and an olefin in cis positions are described. The compounds (1) of general formula [PtR(N-N)(olefin)]BF4 are obtained either through oxidative addition of the trialkyloxonium salt R3O+BF4- to the appropriate three-coordinate precursor [Pt(N-N)(olefin)] or by substitution of an alkene for the chloride in [PtR(Cl)(N-N)] complexes. The complexes are involved in a dynamic process involving the alkene ligand. The rate of alkene exchange is strongly influenced by the steric hindrance of the N-N ligand above and below the coordination plane. This feature also controls the stereochemistry of alkene coordination. Thus, for type 1 derivatives of α-olefins containing the highly crowded diacetyl bis(di-isopropylphenylimine), only one enantiomeric couple has been detected in the temperature range 203−328 K, and its geometry has been tentatively assigned. Finally, the X-ray crystal structure of a representative complex has been determined

Organometallics in Water: Three-Coordinate [Pt⁰(N,N-chelate)(η²-olefin)] Complexes Containing New Chiral Ligands Based on α-d-Mannose

New bidentate nitrogen ligands based on α-D-mannose were prepared and investigated by preparing a family of platinum(0) complexes of formula [Pt(N,N-chelate)(η2-olefin)]. The ability of one N,N-chelate to induce a stereoselective reaction in water was assessed

Oxidative Additions of E−E Bonds (E = Chalcogen) to Group 10 Metals: “Tunable” Cleavage of Se−Se Bonds by Pt(0) Complexes

Oxidative Additions of E−E Bonds (E = Chalcogen) to Group 10 Metals:  “Tunable” Cleavage of Se−Se Bonds by Pt(0) Complexe

Organometallics in Water: Three-Coordinate [Pt⁰(N,N-chelate)(η²-olefin)] Complexes Containing New Chiral Ligands Based on α-d-Mannose

New bidentate nitrogen ligands based on α-D-mannose were prepared and investigated by preparing a family of platinum(0) complexes of formula [Pt(N,N-chelate)(η2-olefin)]. The ability of one N,N-chelate to induce a stereoselective reaction in water was assessed

Synthesis and Characterization of Trigonal-Bipyramidal Platinum(II) Olefin Complexes with Chalcogenide Ligands in Axial Positions. X-ray Molecular Structures of [Pt(SMe)₂(dmphen)(diphenyl fumarate)], Its Cationic Dipositive Derivative [Pt(SMe₂)₂(dmphen)(diphenyl fumarate)][BF₄]₂, and Free Diphenyl Fumarate

The oxidative addition of RE−ER molecules (E = O, R = H, C(O)Ph, C(O)Me; E = S, Se, Te, R = Me, Ph) to Pt(0) precursors [Pt(N,N-chelate)(olefin)] (1:  N,N-chelate = e.g. 2,9-dimethyl-1,10-phenanthroline; olefin = maleic or fumaric ester) has been studied. Symmetrical cleavage of the E−E bonds affords unprecedented trigonal-bipyramidal Pt(II) complexes of the formula [Pt(ER)2(N,N-chelate)(olefin)] (2). Products of type 2, which have been characterized through 1H and 13C NMR spectroscopy, contain chalcogenide ligands in the axial positions. The reactivity of the new compounds has also been investigated. Thus, Pt−OH fragments generated by the addition of H2O2 are acetylated by acetic anhydride. Furthermore, S, Se, and Te coordinated to Pt are readily methylated by trimethyloxonium tetrafluoroborate, affording the first examples of dipositive coordinatively saturated platinum(II) cations (3). The structures of the related neutral [Pt(SMe)2(2,9-dimethyl-1,10-phenanthroline)(diphenyl fumarate)] and cationic [Pt(SMe2)2(2,9-dimethyl-1,10-phenanthroline)(diphenyl fumarate)][BF4]2 compounds have been determined by X-ray diffraction together with that of the free diphenyl fumarate ligand

Mechanism of Silver-Promoted Ligand Metathesis in Square-Planar Complexes of d⁸ Ions. Kinetics of Formation and Molecular Structures of a Trinuclear Intermediate [(Me)(N−N)Pt(μ-Cl)Ag(μ-Cl)Pt(N−N)(Me)]⁺ and Its Dinuclear Evolution Product [(Me)(N−N)Pt(μ-Cl)Pt(N−N)(Me)]⁺ (N−N = ArNC(Me)C(Me)NAr, Ar = 2,6-(<i>i</i>-Pr)₂C₆H₃)

The silver-assisted ligand methatesis reaction involving a platinum(II) complex of formula [PtClMe(N,N-chelate)] with acetonitrile has been investigated. By using a suitably hindered N,N-chelate, an otherwise hardly detectable trinuclear species has been isolated and characterized through X-ray diffractometry. The trinuclear cation consists of two nearly orthogonal [PtCl(Me)(N,N-chelate)] square-planar units entrapping an Ag+ cation through the chloride ligands that, acting as bidentate, form a linear AgCl2 unit with two nonequivalent Ag−Cl bonds. The residual acidity of the silver cation is satisfied by one secondary Ag−Pt interaction [Ag−Pt(1) = 2.82 Å] in which the platinum atom acts as a donor. Kinetic studies have demonstrated that the silver assistance operates both through a simple associative step and through a pathway in which the above trinuclear complex is an active intermediate. In a noncoordinating solvent the latter species evolves with AgCl loss and formation of a dinuclear Pt,Pt complex showing a rare single chloride bridge

Synthesis and Characterization of Trigonal-Bipyramidal Platinum(II) Olefin Complexes with Chalcogenide Ligands in Axial Positions. X-ray Molecular Structures of [Pt(SMe)₂(dmphen)(diphenyl fumarate)], Its Cationic Dipositive Derivative [Pt(SMe₂)₂(dmphen)(diphenyl fumarate)][BF₄]₂, and Free Diphenyl Fumarate

The oxidative addition of RE−ER molecules (E = O, R = H, C(O)Ph, C(O)Me; E = S, Se, Te, R = Me, Ph) to Pt(0) precursors [Pt(N,N-chelate)(olefin)] (1:  N,N-chelate = e.g. 2,9-dimethyl-1,10-phenanthroline; olefin = maleic or fumaric ester) has been studied. Symmetrical cleavage of the E−E bonds affords unprecedented trigonal-bipyramidal Pt(II) complexes of the formula [Pt(ER)2(N,N-chelate)(olefin)] (2). Products of type 2, which have been characterized through 1H and 13C NMR spectroscopy, contain chalcogenide ligands in the axial positions. The reactivity of the new compounds has also been investigated. Thus, Pt−OH fragments generated by the addition of H2O2 are acetylated by acetic anhydride. Furthermore, S, Se, and Te coordinated to Pt are readily methylated by trimethyloxonium tetrafluoroborate, affording the first examples of dipositive coordinatively saturated platinum(II) cations (3). The structures of the related neutral [Pt(SMe)2(2,9-dimethyl-1,10-phenanthroline)(diphenyl fumarate)] and cationic [Pt(SMe2)2(2,9-dimethyl-1,10-phenanthroline)(diphenyl fumarate)][BF4]2 compounds have been determined by X-ray diffraction together with that of the free diphenyl fumarate ligand

Mechanism of Silver-Promoted Ligand Metathesis in Square-Planar Complexes of d⁸ Ions. Kinetics of Formation and Molecular Structures of a Trinuclear Intermediate [(Me)(N−N)Pt(μ-Cl)Ag(μ-Cl)Pt(N−N)(Me)]⁺ and Its Dinuclear Evolution Product [(Me)(N−N)Pt(μ-Cl)Pt(N−N)(Me)]⁺ (N−N = ArNC(Me)C(Me)NAr, Ar = 2,6-(<i>i</i>-Pr)₂C₆H₃)

The silver-assisted ligand methatesis reaction involving a platinum(II) complex of formula [PtClMe(N,N-chelate)] with acetonitrile has been investigated. By using a suitably hindered N,N-chelate, an otherwise hardly detectable trinuclear species has been isolated and characterized through X-ray diffractometry. The trinuclear cation consists of two nearly orthogonal [PtCl(Me)(N,N-chelate)] square-planar units entrapping an Ag+ cation through the chloride ligands that, acting as bidentate, form a linear AgCl2 unit with two nonequivalent Ag−Cl bonds. The residual acidity of the silver cation is satisfied by one secondary Ag−Pt interaction [Ag−Pt(1) = 2.82 Å] in which the platinum atom acts as a donor. Kinetic studies have demonstrated that the silver assistance operates both through a simple associative step and through a pathway in which the above trinuclear complex is an active intermediate. In a noncoordinating solvent the latter species evolves with AgCl loss and formation of a dinuclear Pt,Pt complex showing a rare single chloride bridge