Daniela Belli Dell'Amico

Carbonyl complexes of noble metals with halide ligands: I. Platinum(II) / halide exchange, dimerization, isomerization, 13C NMR data and crystal and molecular structure of Pt2I4(CO)2

Room temperature and atmospheric pressure carbonylation of PtI2 in toluene gave trans-PtI2(CO)2 as the predominant isomer, together with cis-PtI2(CO)2. Lowering of p(CO) resulted in conversion of PtI2(CO)2 into Pt2I4(CO)2 both in solution and in the solid state. The iodide-bridged centrosymmetric Pt2I4(CO)2 was studied by single crystal X-ray diffractometry. Monoclinic; space group C2/c; a 10.772(2); b 9.077(1); c 13.001(3) A; β 112.26(2)°; U 1176.5(5) A3; Z = 4; Dcalc 5.385 g cm−3; Mo-Kα radiation (λ 0.71069 A); μ(Mo-Kα) 343.6 cm−1; F(000) = 1584. The structure consists of Pt2I2(μ-I)2(CO)2 units with tetracoordinated square planar platinum bonded to two bridging iodides, one terminal iodide and one terminal CO group. The PtPt nonbonding distance is 3.846(2) A. A new preparative procedure for the monomeric halo carbonyls PtX2(CO)2 (X  Br, I) involves treatment of cis-PtCl2(CO)2 with dry HX in toluene. Addition of CO to Pt2Br4(CO)2 occurs readily to give cis-PtBr2(CO)2 through the transient trans-PtBr2(CO)2. The 13C NMR spectra data for the platinum complexes show that: (a) values of J(PtC) decreases in the sequence Pt2X4(CO)2 > [PtX3(CO)]− > cis-PtX2 (CO)2 ⪆ trans-PtX2(CO)2 > [PtX5(CO)]−; (b) within each series of compounds, values of J(PtC) decrease in the sequence Cl > Br > I.

A facile synthesis of Zn4(μ4-O)(O2CNMe2)6

Abstract Zn4O(O2CNMe2)6 was synthesized from ZnO and [NH2Me2][O2CNMe2] in MeCN as solvent and characterized by spectroscopic and diffractometric methods.

Halo-carbonyl complexes of platinum(II) and palladium(II)

Abstract The mononuclear and binuclear square-planar complexes of palladium(II) and platinum(II) cis-PtCl2(CO)2 (1), trans- Pt2Cl4(CO)2 (2), cis-PtBr2(CO)2 (3), and cis-Pd2Cl4(CO)2 (4), have been prepared by new synthetic procedures and some of them (2, 3, and 4) structurally characterised by X-ray diffraction methods. In the mononuclear platinum derivatives, cis-PtX2(CO)2, X=Cl, Br, the molecules are arranged in columns, the Pt⋯Pt separation being 3.378 A (X=Cl) or 3.65 A (av., X=Br). The chloride-bridged dinuclear chloro-carbonyl complexes M2Cl4(CO)2, M=Pd, Pt, contain terminal chloride and carbonyl groups, trans for the platinum derivative 2, but, unexpectedly, cis for the corresponding palladium compound 4. Packing is based on intermolecular C⋯X or Pt⋯Pt interactions, as a function of the nature of the halide. The carbonylation at atmospheric pressure and room temperature of the tetrahalo complexes of platinum(II) in the presence of AlX3 as halide scavenger leads to [PtX3(CO)]− or PtX2(CO)2, depending on the Pt/AlX3 molar ratio. The crystal and molecular structural data of [NBu4][PtBr3(CO)] (5), show the anion to have substantially identical Pt–Br bond distances, the CO ligand performing no trans influence.

Carbonyl complexes of noble metals with halide ligands: II. Palladium(II): preparation of Pd2Br4(CO)2 and [PdI3(CO)]−: crystal structures of [Bu4N][PdX3(CO)] X : Cl or Br)

The previously elusive Pd2Br4(CO)2 has been isolated, mixed with PdBr2, from the reaction of PdBr2 with CO under pressure. A centrosymmetric structure is suggested for it on the basis of IR spectral data in solution. Attempts to prepare the corresponding iodo carbonyl complex of palladium(II) failed. The anion [PdI3(CO)]− rapidly undergoes decarbonylation both in solution and in the solid state. The stabilities of the halocarbonyl complexes relative to those of the corresponding halides (PdX2 or Pd2X62−) appear to decrease in the sequence Cl > Br > I. The crystal and molecular structures of the [PdX3(CO)]− anions (X  Cl, Br) with [N-n-Bu4]+ as counter-cation have been determined by X-ray diffraction. Crystal data for [N(n-C4H9)4][PdCl3(CO)]: monoclinic; space group, P21/n; a 18.231(10); b 8.889(4); c 14.978(8) A; β 104.88(2)°; U 2346(2) A3; Z = 4 Dc 1.368 g cm−3; μ(Mo-Kα) 11.29 cm−1; R = 0.0397. Crystal data for [N(n-C4H9)4][PdBr3(CO)] · C2H2Cl4: triclinic; space group, P1−; a 16.667(10); b 10.376(8); c 9.644(7) A; α 74.27(3)°; β 75.12(3)°; γ 83.27(4)°; U 1549(2) A3; Z = 2; Dc 1.681 g cm−3; μ(Mo-Kα) 47.84 cm−1; R = 0.0886. In both anions, which are essentially planar, the PdX bond trans to the CO ligand is not significantly different in length from the other two PdX distances. The overall idealized symmetry of the [N-n-Bu4]+ cation changes from D2d to S4 when the counter-anion is changed from [PdCl3(CO)]− to [PdBr3(CO)]−.

Reactions of anhydrous gold(III) chloride with organic nitriles containing aromatic groups

Abstract When moisture is excluded, gold(III) chloride reacts with nitriles containing aromatic groups to give products of the type AuCl 3 L (e.g. L = PhCN, p -CH 3 C 6 H 4 CN, PhCH 2 CN), not ring metallated products as previously reported.

Synthesis, and crystal and molecular structures of the triflato and trifluoroacetato complexes of zinc, Zn(O3SCF3)2(DME)2 and [Zn(O2CCF3)2(DME)]n

Abstract Anhydrous Zn(O3SCF3)2 and Zn(O2CCX3)2, X=F, Cl, Br were obtained in substantially quantitative yields from ZnO (or ZnEt2 in the case of the bromide derivative) and a mixture of the corresponding acid and anhydride in heptane as medium. The reactions are rapid and moderately exothermic. Recrystallization of the triflate and trifluoroacetate complexes from dimethoxyethane (DME) produced single crystals of Zn(O3SCF3)2(DME)2 (1) and [Zn(O2CCF3)2(DME)]n (2) suitable for X-ray diffraction studies. In both compounds zinc is hexacoordinated with a pseudo-octahedral geometry. Compound 1 is constituted by mononuclear molecules with terminal monodentate O3SCF3 ligands in trans position. A polynuclear chain structure was found for 2 with zinc atoms joined alternatively by triple and single carboxylato bridges, and with bidentate terminal DME.

N,N-Dialkylcarbamato complexes as precursors for the chemical implantation of metal cations on a silica support. Part I. Tin

Abstract Chemical implantation of tin on a commercial silica has been carried out by using the hydrocarbon soluble Sn(O 2 CN i Pr 2 ) 4 as precursor, the N,N -dialkylcarbamato group is chemically displaced by the silanol groups of the support under mild conditions.

N,N-Dialkylcarbamato complexes as precursors for the chemical implantation of metal cations on a silica support

Implantation of platinum(ii) on a commercial silica has been carried out under mild conditions by usingN,N-dialkylcarbamato complexes as reactive precursors, in a biphasic liquid/solid system, carbon dioxide and secondary amine being released during the reaction with the acidic silanol groups of the support. Information about the coordination sphere of the silica-supported platinum(ii) has been obtained by IR, XPS, solid-state NMR spectroscopy and WAXS measurements, which agree with chemical evidence. Reduction, either thermal or with dihydrogen, produces platinum nanoparticles, which were studied by conventional techniques and shown to be catalytically active in the hydrogenation of cyclohexene.

Nanostructured Copper Oxide on Silica–Zirconia Mixed Oxides by Chemical Implantation

N,N-Dialkylcarbamato complexes of copper(II), [Cu(O(2)CNR(2))(2)] (R = All = allyl, C(3)H(5); iPr, CH(CH(3))(2)) were prepared with the aim of functionalizing silica and nanostructured silica-zirconia matrices. The mixed matrices for the grafting reactions were prepared by copolymerizing MAPTMS (methacryloxypropyltrimethoxysilane), the precursor for the silica matrix, with the zirconium tetranuclear derivative [Zr(4)O(2)(OMc)(12)] (OMc = methacrylate), the precursor for the zirconia nanoparticles. Suspension of the silica and silica-zirconia matrices in a solution of the copper dialkylcarbamate led to the functionalization of the respective substrates. The composition, microstructure, morphology, and physicochemical nature of the copper species grafted on the matrices were investigated by FTIR, X-ray photoelectron spectroscopy (XPS), EPR, X-ray absorption spectroscopy (XAS), XRD, TEM, and dinitrogen adsorption. The effect of selected experimental parameters (the nature of the copper precursor and of the matrix, grafting time, thermal treatment) on the grafting reaction was investigated. The Cu/Si ratio is increased by increasing the grafting time and the ZrO(2)-SiO(2) matrix is more reactive to attack by the carbamato complexes than either prepared or commercial SiO(2). After functionalization of the matrix, thermal treatment yielded nanostructured copper(II) oxide clusters, average diameter 12-15 nm, uniformly supported on the silica and on the silica-zirconia matrices.

Metal ion implantation onto acidic resins upon reaction of metal acetates and carbamates: Part I. Synthetic results

Abstract Moderately cross-linked gel-type resins bearing –SO3H, –COOH and –OH groups undergo facile metallation with PdII, CuII and NiII acetates with concomitant release of acetic acid. Successful and facile metallation is also observed upon reaction with PdII, CuII and NiII carbamates.