Giuseppe Fachinetti

Carbon Dioxide Hydrogenation to Formic Acid by Using a Heterogeneous Gold Catalyst

AUROlite, consisting of gold supported on titania (picture shows extrudates in a steel net cage), is a robust catalyst for the production of catalyst-free HCOOH/NEt(3) adducts from H(2), CO(2), and neat NEt(3). Pure HCOOH is freed from the adducts by amine exchange.

Stoicheiometric reduction of CO and CO2 to methanol: evidence for carbon monoxide insertion into zirconium–hydrogen bond

The reaction of carbon monoxide with bis(η5-cyclopentadienyl)hydridochlorozirconium(IV), cp2Zr-(H)Cl, at room temperature and atmospheric pressure, leads to a dinuclear zirconium(IV) derivative (cp2ZrCl)2CH2O; replacing CO by CO2 in this reaction results in the quantitative formation of cp2ZrCl(OMe) and (cp2ZrCl)2O.

Carbon monoxide insertion into zirconium– and hafnium–carbon σ-bonds: synthesis, and structural and thermodynamic data for alkyl- and aryl-η-acylbis(η-cyclopentadienyl)derivatives of zirconium(IV) and hafnium(IV)

Carbonylation of toluene solutions of bis(η-cyclopentadientyl)diphenyl-zirconium(IV) and -hafnium(IV), [M(cp)2(Ph)2](cp =η-C5H5; M = Zr or Hf), with CO at atmospheric pressure gave acyl derivatives [M(cp)2(COPh)(Ph)][ν(CO)= 1 500 cm–1]. The same results were obtained for [M(cp)2R2](M = Zr or Hf; R = CH2Ph or Me), but in these cases the carbonyl insertion was found to be reversible. The isolation of [M(cp)2(COR)R][ν(CO)= 1 530–1 550 cm–] was possible only for zirconium, while under the same conditions equilibrium constants and thermodynamic data were obtained for CO insertion into the Hf–Me (ΔH⊖=–12.7 ± 1.6 kcal mol–1; ΔS⊖=–33.0 ± 5.6 cal K–1 mol–1) and Hf–CH2Ph (ΔH⊖=–11.5 ± 0.2 kcal mol–1; ΔS⊖=–28.7 ± 0.6 cal K–1 mol–1) bonds. All the acyls show a low CO stretching frequency, which indicates an η-acyl bonded group, as was confirmed by X-ray structural data.

The crystal structure of 1,1-bis(η5-cyclopentadienyl)-2,3,4,5-tetraphenylzirconole

The crystal and molecular structure of (η 5 -C 5 H 5 ) 2 Zr[C 4 (C 6 H 5 ) 4 ] has been determined by single crystal X-ray diffraction methods. The compound is isostructural with its titanium and hafnium analogues, and crystallizes in the monoclinic space group P 2 1 / n with unit cell parameters a = 13.790(5), b = 11.136(5), c = 18.692(7) », β = 92.82(4)°, and ϱ calc = 1.34 g cm −3 for Z = 4. Full-matrix least-squares refinement converged with a conventional R value of 0.049 for 2986 observed reflections. The metallocyclic ring is planar to within 0.05 », and the π-electron density is largely localized. The two independent ZrC(σ) bond lengths are 2.250(5) and 2.265(6) ». The ZrC(η 5 ) distances range from 2.482(6) to 2.546(7) », and average 2.521(20) ». A comparison of zirconium- and hafnium-carbon bonds based on the data available shows that for M = Hf the MC bonds are shorter for all cases: C( sp ), C( sp 2 ), C( sp 3 ), C(η 5 ).

Aerobic, Copper‐Mediated Oxidation of Alkaline Formaldehyde to Fuel‐Cell Grade Hydrogen and Formate: Mechanism and Applications

Beyond nanopowders: Hydrogen and formate are produced through the oxidation of alkaline HCHO by CuO microparticles. The Cu microparticles formed in the purely electrochemical reduction of CuO preserve the morphology of CuO (left-hand image: CuO; right-hand image: Cu formed in the reduction of CuO by alkaline HCHO) and can be permeated by a gas. They react more efficiently than Cu nanoparticles with air to restore CuO.

Sodium [NN′-ethylenebis(salicylideneiminato)cobaltate(I)], a reversible carbon dioxide carrier

The reaction of sodium [NN′-ethylenebis(salicylideneiminato)cobaltate(I)] with carbon dioxide in both tetrahydrofuran and pyridine gave the reversible adducts: Co(salen)CO2Na and (py)Co(salen)CO2Na, respectively, containing CO2 as the reduced species and in bent form.

Pyridine induced disproportionation reaction of Co2(CO)8 in THF: Homonuclear ion pairs and dihydrogen activation

Abstract The IR spectra of the Co 2+ /Py/Co(CO) 4 − , system in THF reveal complex associative phenomena. Three kinds of homonuclear ion pairs were distinguished by means of variable temperature IR spectroscopy. Under the conditions in which these associative equilibria exist cobalt(II) is reduced by dihydrogen to cobalt( −I) under 1 atm of syngas at room temperature.

Dicarbonylbis(η-cyclopentadienyl)titanium(II) chemistry: reactions with organic molecules containing C–Cl, P–Cl, O–H, and S–Cl bonds; synthesis, properties, and structures of η-acyl derivatives of titanium(IV)

The reaction of [Ti(cp)2(CO)2](1)(cp =η-C5H5) with acyl halides RCOCl (R = Me or Ph) gives acyl derivatives of titanium(IV), [Ti(cp)2(COR)Cl]. Under the same conditions, the reaction of (1) with alkyl iodides gives the acyl derivatives [Ti(cp)2(COR)I](R = Me, Et, Pri, or Bus). All the acyl derivatives are characterised by a low CO stretching frequency [ν(CO) at ca. 1 600 cm–1]. X-Ray analysis of [Ti(cp)2(COMe)Cl] shows that the molecule has Cs symmetry with atoms Ti and Cl and the acetyl group lying in the crystallographic mirror plane. The Ti atom has distorted tetrahedral co-ordination, and it interacts strongly with the oxygen of the acetyl group which acts as a bidentate three-electron ligand. This structure explains the observed low CO stretching frequency for the acyl unit. Reaction with MeSO2Cl resulted in insertion of the Ti(cp)2 unit into the S–Cl bond giving [Ti(cp)2(O2SMe)Cl]. Reactions of (1) with iodide, phenanthrene-9,10-quinone. and PPh2Cl are also reported.

Preparation and crystal and molecular structure of two trialkylamine adducts of HCo(CO)4 showing a preferential NR3H+⋯[(OC)3Co(CO)]– interaction

HCo(CO)4 and trialkylamines in hydrocarbon solution form 1:1 adducts, which may be described as NR3H+⋯[Co(CO)4]– ion pairs; X-ray crystal structure determinations show that in the solid state the inter-acting unit NEt2H+⋯[Co(CO)4]– has an N ⋯ Co contact of 3.72 A with the nitrogen hydrogen on the threefold axis of rotation interacting with the C3Co part of the [Co(CO)4]– anion, in a sort of ‘elongated’ HCo(CO)4 structure, and a substantially similar molecular structure was found for NMe3H+⋯[Co(CO)4]–, the N ⋯ Co contact being reduced to 3.39 A.

Structure and properties of carbonylbis(η-cyclopentadienyl)(η-diphenyl-acetylene) titanium: the first titanium complex containing a two-carbon η-bonded ligand

The reaction of [Ti(cp)2(CO)2](cp =η-C5H5) with diphenylacetylene gives mononuclear [Ti(cp)2(C2Ph2)(CO)] characterised by ν(CO) at 1 995 and ν(CC) at 1 780 cm–1 The new complex shows high catalytic activity in the hydrogenation of olefins and acetylenes at room temperature under 1 atm of H2. At >30 °C and in solutions of aromatic hydrocarbons it decomposes to [Ti(cp)2(CO)2] and [[graphic omitted]Ph)]. Its stability in the solid state has allowed an X-ray structural analysis: orthorhombic, space group P212121, a= 18.464(5), b= 13.301(4), c= 7.822(4)A. Z= 4, and Dc= 1.49 g cm–3. Full-matrix least-squares refinement has led to a final R value of 0.067 based on 1 647 independent observed reflections. The titanium atom is η-bonded to two C5H5 rings and η-bonded to the diphenylacetylene ligand. The two ‘eclipsed’ C5H5 rings are bent back to make room in the horizontal (molecular) plane for a CO ligand and a ‘σ,π’-bonded C2Ph2 molecule. The Ti–C(CO) and C–O bond lengths [2.050(8) and 1 .130(10)A] are consistentwith the CO being bonded to titanium as in [Ti(cp)2(CO)2]. The Ti–C(C2Ph2) bond lengths [2.107(7) and 2.230(7)A], together with the CC bond distance [1.285(10)A] and CC–Ph deformation angles [I 38.8(7) and 145.8(7)°], suggest a metallocyclopropene structure for the titanium–diphenylacetylene interaction.