Coordination Chemistry of Ester-Functionalized Cp Ligands. The Atom-Economy Synthesis of Na[C₅H₄CO₂(CH₂)₂OH] and Solid State Structures of [Rh{C₅H₄CO₂(CH₂)₂OH}(CO)₂] and [Rh₂{μ-(C₅H₄CO₂CH₂)₂}(NBD)₂]

The one-step synthesis of Na[C5H4CO2CH2CHCH2] (1) from NaCp and diallyl carbonate is presented together with a simple pathway for the synthesis of sodium hydroxyalkoxycarbonylcyclopentadienide, Na[C5H4CO2(CH2)2OH] (2). The latter new reagent is obtained in high yield by reacting NaCp with 1,3-dioxolan-2-one (ethylene carbonate). When (±)-4-methyl-1,3-dioxolan-2-one [(±)-1,2-propylene carbonate] is used, the ring-opening reaction leads to a mixture of the two regioisomers Na[C5H4CO2CH2CH(Me)OH] (3a) and Na[C5H4CO2CH(Me)CH2OH] (3b) in a 7:3 ratio. Reactions of 1 and 2 with FeCl2 and [Rh(L,L)Cl]2 [L,L = CO or L,L = 2,5-norbornadiene (NBD)] lead to the respective metal complexes [Fe(C5H4CO2CH2CHCH2)2] (4), [Fe{C5H4CO2(CH2)2OH}2] (5), [Rh(C5H4CO2CH2CHCH2)(CO)2] (6), [Rh{C5H4CO2(CH2)2OH}(CO)2] (7), and [Rh{C5H4CO2(CH2)2OH}(NBD)] (8). Additionally in the reaction of 2 with [Rh(L,L)Cl]2 the diester-bridged dinuclear adducts [Rh2{μ-(C5H4CO2CH2)2}(L,L)2] [L,L = CO (9); L,L = NBD (10)] are isolated. The reaction of 2 with MBr(CO)5 (M = Mn, Re) leads to [M{C5H4CO2(CH2)2OH}(CO)3] [M = Mn (11); M = Re (12)] together with a complex mixture of unidentified metal carbonyls. The X-ray molecular structures of 7 and 10 are reported

Addition−Elimination Equilibria Involving 16e^- Platinum(0) and 18e^- Platinum(II) Complexes

The addition−elimination equilibrium involving a platinum(0) nucleophile [Pt(N,N‘-chelate)(olefin)] (1), an organometal electrophile RmMXn (M = Hg, Sn; X = Cl, Br, I; R = hydrocarbyl group), and the corresponding five-coordinate adduct [PtX(MRmXn-1)(N,N‘-chelate)(olefin)] (2) has been investigated. The influence on the equilibrium of the groups bonded to the electrophilic center and of the ligands bonded to platinum has been evaluated. It has been found that the adduct is stabilized by the presence of electron-donor olefins on platinum and of electron-withdrawing groups on the electrophilic metal. It has also been found that the influence of the halide moving onto platinum can be rationalized in terms of the relative softness of the two metals involved in the equilibrium. The X-ray molecular structures of [Pt(dmphen)(E-MeO2CCHCHCO2Me)] (1k, dmphen = 2,9-Me2-1,10-phenanthroline) and of the related addition product [PtCl(SnMe2Cl)(dmphen)(E-MeO2CCHCHCO2Me)] (2i) have been determined for a better understanding of the influence of steric and bonding features

Coordination Chemistry of Ester-Functionalized Cp Ligands. The Atom-Economy Synthesis of Na[C₅H₄CO₂(CH₂)₂OH] and Solid State Structures of [Rh{C₅H₄CO₂(CH₂)₂OH}(CO)₂] and [Rh₂{μ-(C₅H₄CO₂CH₂)₂}(NBD)₂]

The one-step synthesis of Na[C5H4CO2CH2CHCH2] (1) from NaCp and diallyl carbonate is presented together with a simple pathway for the synthesis of sodium hydroxyalkoxycarbonylcyclopentadienide, Na[C5H4CO2(CH2)2OH] (2). The latter new reagent is obtained in high yield by reacting NaCp with 1,3-dioxolan-2-one (ethylene carbonate). When (±)-4-methyl-1,3-dioxolan-2-one [(±)-1,2-propylene carbonate] is used, the ring-opening reaction leads to a mixture of the two regioisomers Na[C5H4CO2CH2CH(Me)OH] (3a) and Na[C5H4CO2CH(Me)CH2OH] (3b) in a 7:3 ratio. Reactions of 1 and 2 with FeCl2 and [Rh(L,L)Cl]2 [L,L = CO or L,L = 2,5-norbornadiene (NBD)] lead to the respective metal complexes [Fe(C5H4CO2CH2CHCH2)2] (4), [Fe{C5H4CO2(CH2)2OH}2] (5), [Rh(C5H4CO2CH2CHCH2)(CO)2] (6), [Rh{C5H4CO2(CH2)2OH}(CO)2] (7), and [Rh{C5H4CO2(CH2)2OH}(NBD)] (8). Additionally in the reaction of 2 with [Rh(L,L)Cl]2 the diester-bridged dinuclear adducts [Rh2{μ-(C5H4CO2CH2)2}(L,L)2] [L,L = CO (9); L,L = NBD (10)] are isolated. The reaction of 2 with MBr(CO)5 (M = Mn, Re) leads to [M{C5H4CO2(CH2)2OH}(CO)3] [M = Mn (11); M = Re (12)] together with a complex mixture of unidentified metal carbonyls. The X-ray molecular structures of 7 and 10 are reported

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

Synthesis of [Au₃Fe₂(CO)₈(dppm)]^- and [Au₅Fe₂(CO)₈(dppm)₂]⁺: X-ray Structures of [NEt₄][Au₃Fe₂(CO)₈(dppm)] and [Au₅Fe₂(CO)₈(dppm)₂][BF₄]

The [Au3Fe2(CO)8(dppm)]- cluster anion has been isolated from the reaction of either [AuFe2(CO)8]3- or [Fe(CO)4]2- with Au2(dppm)Cl2 in THF, whereas the [Au5Fe2(CO)8(dppm)2]+ cluster cation has been obtained by oxidation of the former; both new compounds have been characterized by X-ray studies on their [NEt4][Au3Fe2(CO)8(dppm)] and [Au5Fe2(CO)8(dppm)2][BF4] salts, respectively

First Coordinatively Saturated Carbene Complexes of Platinum(II): Synthesis, Structure, and Reactivity

Coordinatively saturated carbene complexes of platinum(II) have been obtained by oxidative addition of [ClCHNMe2]Cl to Pt(0) precursors. The cationic products of general formula [PtCl(CHNMe2)(N,N-chelate)(olefin)]Cl have been characterized through NMR spectroscopy and for [PtCl(CHNMe2)(2,9-Me2-1,10-phen)(Z-MeO2CCHCHCO2Me)]Cl by X-ray diffractometry. The latter species reacts with nucleophiles affording dimethylformamide and the corresponding Pt(0) precursor [Pt(2,9-Me2-1,10-phen)(Z-MeO2CCHCHCO2Me)]. Attempts to obtain related complexes containing carbene groups PtCHY without a heteroatom in α-position (Y = CO2Et, CO2NMe2, CN) have led to the isolation of complexes of formula [PtR(dmphen){η1,η2-CH(Y)O2CCHCHCO2Me}] (R = Me, Ph), formally derived from an intramolecular nucleophilic addition to a carbene intermediate. The X-ray structure of a representative product, [PtMe(dmphen){η1,η2-CH(CO2Et)O2CCHCHCO2Me}], is reported

Coordination Chemistry of Cyclopentadienyl Ester-Disubstituted Ligands. Synthesis and Solid State Structures of [Na([18]-crown-6)][C₅H₃(CO₂Et)₂-1,2] and [Mn{C₅H₃(CO₂Ph)₂-1,2}(CO)₃]

The disubstituted alkyl- and aryloxycarbonylcyclopentadienides of sodium Na[C5H3(CO2R)2-1,2] [R = Me (3a), Et (3b), Ph (3c)] are obtained in a two-step synthesis. The known Na[C5H4(CO2R)] [R = Me (1a), Et (2b)] and the hitherto unknown Na[C5H4(CO2Ph)] (1c), prepared from NaCp and dialkyl- or diphenyl carbonate, are subsequently reacted with the corresponding chloroformates ROCOCl to give 3 contamined with variable amounts of 1,3 isomers. Treatment of 3b with [18]-crown-6 affords the buff-colored crystalline salt [Na([18]-crown-6)][C5H3(CO2Et)2-1,2] (4b). Reactions of 4b and 3c with MBr(CO)5 [M = Mn, Re] or [RuCl2(CO)3]2 lead to the respective metal complexes [M{η5-C5H3(CO2R)2-1,2}(CO)3] [R = Et and M = Mn (5b) or Re (6b), R = Ph and M = Mn (5c)] and [Ru{C5H3(CO2Et)2-1,2}(CO)]2(7b). The solid state structure of 4b reveals ion pairs in which the anion adopts an idealized C2v conformation and chelates the sodium (κ2O,O‘-coordination). The structure of [Mn{C5H3(CO2Ph)2-1,2}(CO)3] (5c) confirms the expected η5-coordination of the Cp ring and exhibits significant torsion angles between the Cp ring and carboxylate groups

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

Coordination Chemistry of Cyclopentadienyl Ester-Disubstituted Ligands. Synthesis and Solid State Structures of [Na([18]-crown-6)][C₅H₃(CO₂Et)₂-1,2] and [Mn{C₅H₃(CO₂Ph)₂-1,2}(CO)₃]

The disubstituted alkyl- and aryloxycarbonylcyclopentadienides of sodium Na[C5H3(CO2R)2-1,2] [R = Me (3a), Et (3b), Ph (3c)] are obtained in a two-step synthesis. The known Na[C5H4(CO2R)] [R = Me (1a), Et (2b)] and the hitherto unknown Na[C5H4(CO2Ph)] (1c), prepared from NaCp and dialkyl- or diphenyl carbonate, are subsequently reacted with the corresponding chloroformates ROCOCl to give 3 contamined with variable amounts of 1,3 isomers. Treatment of 3b with [18]-crown-6 affords the buff-colored crystalline salt [Na([18]-crown-6)][C5H3(CO2Et)2-1,2] (4b). Reactions of 4b and 3c with MBr(CO)5 [M = Mn, Re] or [RuCl2(CO)3]2 lead to the respective metal complexes [M{η5-C5H3(CO2R)2-1,2}(CO)3] [R = Et and M = Mn (5b) or Re (6b), R = Ph and M = Mn (5c)] and [Ru{C5H3(CO2Et)2-1,2}(CO)]2(7b). The solid state structure of 4b reveals ion pairs in which the anion adopts an idealized C2v conformation and chelates the sodium (κ2O,O‘-coordination). The structure of [Mn{C5H3(CO2Ph)2-1,2}(CO)3] (5c) confirms the expected η5-coordination of the Cp ring and exhibits significant torsion angles between the Cp ring and carboxylate groups

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