Copper Carbonyl Research Articles

Infrared Photodissociation Spectroscopy of Copper Carbonyl Cations

Copper carbonyl cations of the form Cu(CO)(n)(+) (n = 1-8) are produced in a molecular beam via laser vaporization in a pulsed nozzle source. Mass-selected infrared photodissociation spectroscopy in the carbonyl stretching region is used to study these ions and their argon "tagged" analogues. The geometries and electronic states of these complexes are determined by the number of infrared-active bands, their frequency positions, and their relative intensities compared to the predictions of theory. Cu(CO)(4)(+) has a completed coordination sphere, consistent with its expected 18-electron stability. It also has a tetrahedral structure similar to that of its neutral isoelectronic analog Ni(CO)(4). The carbonyl stretch in Cu(CO)(4)(+) (2198 cm(-1)) is blue-shifted with respect to the free CO vibration (2143 cm(-1)), providing evidence that this is a "non-classical" metal carbonyl.

Morphological dependency of polymer electrolyte membranes on transient salt type: effects of anion species

AbstractTwo types of transition metal salts, i.e. Cu(NO3)2 and CuCl2, with different anion species were used to prepare various polyethersulfone‐based poly(N‐vinyl pyrrolidone) (PVP) composite membranes. The polymer crystallinity, strength of some of the bonds in the membrane structure and effects of anion species on the membrane morphology were investigated through X‐ray diffraction (XRD), scanning electron microscopy with energy‐dispersive X‐ray spectrometry (SEM‐EDX), Fourier transform infrared (FTIR) spectroscopy and atomic force microscopy. The XRD results indicated an enhancement of the PVP crystallinity after addition of Cu(NO3)2. Moreover, addition of copper salt was accompanied by an increase of effective membrane distances. The FTIR analysis revealed that the nitrate ions might be better distributed than the other salt ions. The complexes created between them and carbonyl oxygens on the PVP chains were thus stronger. More powerful interactions caused a crystallinity enhancement following the addition of Cu(NO3)2. The SEM‐EDX experiment gave insight into the copper ion and carbonyl oxygen distributions in the membrane surface and active layer. The uniform distribution of copper ions resulted in a clear distribution of interchain interactions and complexes in the active layer structure and also caused structural order improvement. Copyright © 2010 Society of Chemical Industry

ChemInform Abstract: Synthesis of Cycloprop(c)indol-5-ones from 4-Diazo-3-(N-(2-propenyl) amido)cyclohexadien-1-ones. Exploration of Copper(I) and Copper(II) Complexes as Catalysts.

The cyclization of 4-diazo-3-[N-(2-propenyl)amido]cyclohexadienones to cycloprop[c]indol-5-ones under the influence of copper(I) and copper(II) compounds has been investigated. Catalysis is observed with copper(I) triflate, the carbon monoxide complexe of copper(I) triflate, and the carbon monoxide complexes of trifluoropentanedionato- and hexafluoropentanedionatocopper(I). The best results, essentially quantitative conversion, are achieved with a catalyst solution containing trifluoropentanedionatocopper(I) carbonyl and 1 equiv of n-butalymine. No significant enantioselectivity is observed with a chiral salicyliminatocopper(II), [(trifluoroacetyl)camphorato]copper(I) carbonyl, or a trifluoropentanedionatocopper(I) carbonyl solution containing (S)-α-naphthylethylamine. A mechanistic interpretation involving reductive dediazonization, exo-trig radical cyclization, and cyclopropane formation by the resulting intermediate is proposed

Formation of volatile copper carbonyl during the preparation of copper nanoparticles in the copper acetate hydrate-polyacrylonitrile heterogeneous system under IR radiation

The products of reactions induced by IR heating in the copper acetate hydrate-polyacrylonitrile system and the intermediate Cu compounds formed during the preparation of Cu nanoparticles were studied by powder X-ray diffraction, atomic absorption spectroscopy, mass spectrometry, and IR spectroscopy. Mass spectra of the volatile products formed from the nanocomposite contain peaks typical of the CuCO molecular ion. After treatment of the nanocomposite at 500°C, the copper content in the composite decreased 10-fold as a result of evolution of volatile CuCO.

CO-promoted N2 adsorption on copper atoms

Reactions of laser-ablated copper atoms with carbon monoxide and dinitrogen in excess argon have been investigated by matrix-isolation infrared spectroscopy. The NNCuCO and (NN)(2)CuCO complexes, as well as copper carbonyls, are formed as reaction products during sample deposition and further annealing whereas no copper dinitrogen complexes were observed. These carbonylcopper dinitrogen complexes are characterized on the basis of the results of the isotopic substitution and the reagent concentration change. Density functional theory calculations of the geometry structures, vibrational frequencies, relative absorption intensities, and isotopic shifts strongly support the experimental assignments. The experimental results reveal promoted adsorption of N(2) on Cu atoms by preadsorbed CO. The theoretical results for reaction characteristics between the coadsorbed CO and N(2) agree with the experimental findings. The joint investigations provide insights with regard to CO and N(2) cooperative adsorption effects and consequent reaction mechanisms.

In situ synthesis and crystal growth of copper(I) carbonyl trifluoroacetate: a dinuclear [Cu2(O2CCF3)2(CO)2] core structure confirmed

Abstract The solid state structure of the long known but inadequately characterized compound, namely the mixed ligand copper(I) carbonyl trifluoroacetate, [Cu2(O2CCF3)2(CO)2] (1), has been determined by single crystal X-ray crystallography. Instead of the previously assigned tetranuclear core structure, its main building block is now confirmed to be a dinuclear copper(I) unit that is cis-bridged by two trifluoroacetate ligands. The Cu · · · Cu separation within the unit is 3.1382(6) Å. Additionally, each copper center has one terminally bound carbonyl with a Cu–C distance of 1.806(3) Å. In the solid state, 1 displays a 1D chain structure comprised of the [Cu2(μ 2-O2CCF3)2(CO)2] units held by axial Cu · · · O interactions at 2.2181(13) Å.

Carbon monoxide and ethylene complexes of copper and silver supported by a highly fluorinated tris(triazolyl)borate

Copper and silver carbonyl and ethylene adducts supported by the highly fluorinated hydridotris(triazolyl)borate ligand [HB(3,5-(CF3)2Tz)3]- have been synthesized and characterized, and compared to the analogous complexes based on the hydridotris(pyrazolyl)borate ligand [HB(3,5-(CF3)2Pz)3]-. 1H and 13C NMR signals of the ethylene moiety of [HB(3,5-(CF3)2Tz)3]Cu(C2H4) and [HB(3,5-(CF3)2Tz)3]Ag(C2H4) appear at a relatively downfield position from the corresponding signals of the [HB(3,5-(CF3)2Pz)3]Cu(C2H4) and [HB(3,5-(CF3)2Pz)3]Ag(C2H4) complexes. This indicates the presence of relatively acidic metal sites in the [HB(3,5-(CF3)2Tz)3]- supported molecules. [HB(3,5-(CF3)2Tz)3]- is also a relatively weaker donor compared to the tris(pyrazolyl)borate version [HB(3,5-(CF3)2Pz)3]-. However, the CO stretching frequency values of [HB(3,5-(CF3)2Tz)3]CuCO (2138 cm(-1)) and [HB(3,5-(CF3)2Pz)3]CuCO (2137 cm(-1)) are essentially identical, and did not reflect the differences in the acidity of the metal sites. The analogous silver carbonyl adducts [HB(3,5-(CF3)2Tz)3]AgCO and [HB(3,5-(CF3)2Pz)3]AgCO also show similar nuCO values (2178 cm(-1)). These results illustrate the limitation of using the nu(CO) value of metal carbonyls as a sole indicator of the electronic structure of metal sites in some metal complexes, especially when the metal-->CO pi-back bonding is less important, and the nuCO values of two adducts are unexpectedly similar and appear at a region closer to that of the free CO (2143 cm(-1)).

Sandwiched sodium and half-sandwiched copper carbonyl complexes featuring polyfluorinated tris(triazolyl)borate [HB(3,5-(CF3)2Tz)3]−

Fluorinated tris(triazolyl)borate [HB(3,5-(CF(3))(2)Tz)(3)](-) (Tz = triazolyl) affords the isolation of [Na(THF)(6)]{[HB(3,5-(CF(3))(2)Tz)(3)](2)Na} with a ligand sandwiched sodium ion and a copper carbonyl complex [HB(3,5-(CF(3))(2)Tz)(3)]CuCO with a high C-O stretching frequency.

A non-classical copper carbonyl on a tri-alkene hydrocarbon support

Two rare copper complexes, a tri-alkene adduct [Cu(ttt-cdt)(FSbF(5))] and a non-classical carbon monoxide complex [Cu(ttt-cdt)(CO)][SbF(6)] with a high CO stretching frequency ([small nu, Greek, macron](CO) = 2160 cm(-1)), have been isolated using trans,trans,trans-1,5,9-cyclododecatriene (ttt-cdt) ligand.

Carbon Monoxide Coordination and Reversible Photodissociation in Copper(I) Pyridylalkylamine Compounds

Systematic studies of CO coordination and photodissociation have been carried out for a series of copper(I) carbonyl compounds possessing tripodal tetradentate ligands, [CuI(L)(CO)]B(C6F5)4 (L = Me2N-TMPA (1Me2N), MeO-TMPA (1MeO), H-TMPA (1H), PMEA (2pmea), PMAP (2pmap), BQPA (3bqpa). Detailed structural, electrochemical, and infrared characterization has been accomplished. In addition, various experimental techniques were utilized to determine equilibrium binding constants (KCO), association (kCO), and dissociation (k-CO) rate constants, as well as the thermodynamic (DeltaH degrees , DeltaS degrees ) and activation parameters (DeltaH, DeltaS) that regulate these processes. With increased ligand-electron-donating ability, greater pi back-bonding results in stronger Cu-CO bonds, leading to KCO values on the order 1Me2N-CO > 1MeO-CO > 1H-CO. With systematic synthetic expansion of the five-membered chelate rings like 1R to six-membered chelate rings like 2R, the stability of the CO adduct decreases, 1H-CO > 2pmea-CO > 2pmap-CO. The CO-binding properties of 3bqpa did not follow trends observed for the other compounds, presumably because of its bulkier ligand framework. Through solid- and solution-state analyses, we concluded that the photolabile carbonyl species in solution possess a tridentate coordination mode, forming strictly five-membered chelate rings to the copper ion with one dangling arm of the tripodal ligand. Carbon monoxide reversibly photodissociated from complexes 1Me2N-CO, 1MeO-CO, 1H-CO, and 3bqpa-CO in coordinating (CH3CN) and weakly coordinating (THF) solvent but not from 2pmea-CO and 2pmap-CO. Comparisons to O2-binding data available for these copper complexes as well as to small molecule (O2, CO, NO) reactions with hemes and copper proteins are discussed.

Infrared Spectroscopic and Theoretical Studies on the Reactions of Copper Atoms with Carbon Monoxide and Nitric Oxide Molecules in Rare-Gas Matrices

Reactions of laser-ablated Cu atoms with CO and NO mixtures in solid argon and neon have been investigated using matrix-isolation infrared spectroscopy. Copper carbonyls and copper nitrosyls have been observed, whereas copper carbonyl nitrosyl complexes are absent from the present experiments. New products, (CuCO)2, [NO]Cu[NO], Cu2(mu2-NO), and Cu(NO)2Cu, have been formed in the copper experiments and characterized using infrared spectroscopy on the basis of the results of the isotopic shifts, mixed isotopic splitting patterns, stepwise annealing, the change of reagent concentration and laser energy, and comparison with theoretical predictions. Density functional theory calculations have been performed on these copper carbonyls and copper nitrosyls, which support the identification of these products from the matrix infrared spectrum. A plausible reaction mechanism has been proposed to account for the formation of copper carbonyls and copper nitrosyls. Similar matrix experiments with Ag and Au produce no new species.

63Cu NMR Spectroscopy of Copper(I) Complexes with Various Tridentate Ligands: CO as a Useful 63Cu NMR Probe for Sharpening 63Cu NMR Signals and Analyzing the Electronic Donor Effect of a Ligand

63Cu NMR spectroscopic studies of copper(I) complexes with various N-donor tridentate ligands are reported. As has been previously reported for most copper(I) complexes, 63Cu NMR signals, when acetonitrile is coordinated to copper(I) complexes of these tridentate ligands, are broad or undetectable. However, when CO is bound to tridentate copper(I) complexes, the 63Cu NMR signals become much sharper and show a large downfield shift compared to those for the corresponding acetonitrile complexes. Temperature dependence of 63Cu NMR signals for these copper(I) complexes show that a quadrupole relaxation process is much more significant to their 63Cu NMR line widths than a ligand exchange process. Therefore, an electronic effect of the copper bound CO makes the 63Cu NMR signal sharp and easily detected. The large downfield shift for the copper(I) carbonyl complex can be explained by a paramagnetic shielding effect induced by the copper bound CO, which amplifies small structural and electronic changes that occur around the copper ion to be easily detected in their 63Cu NMR shifts. This is evidenced by the correlation between the 63Cu NMR shifts for the copper(I) carbonyl complexes and their nu(C[triple bond]O) values. Furthermore, the 63Cu NMR shifts for copper(I) carbonyl complexes with imino-type tridentate ligands show a different correlation line with those for amino-type tridentate ligands. On the other hand, 13C NMR shifts for the copper bound 13CO for these copper(I) carbonyl complexes do not correlate with the nu(C[triple bond]O) values. The X-ray crystal structures of these copper(I) carbonyl complexes do not show any evidence of a significant structural change around the Cu-CO moiety. The findings herein indicate that CO complexation makes 63Cu NMR spectroscopy much more useful for Cu(I) chemistry.

Mononuclear and Dinuclear Copper(I) Complexes of Bis(3,5-dimethylpyrazol-1-yl)methane: Synthesis, Structure, and Reactivity

The synthesis and structures of a mononuclear copper(I) carbonyl complex [Cu(OClO3)(CO)(H2CPz2')] (3) and a dinuclear copper(I) carbonyl complex [{Cu(CO)(H2CPz2')}2(mu-pyrazine)](ClO4)2 (4), where H2CPz2' = bis(3,5-dimethylpyrazol-1-yl)methane, are described. These two compounds were generated by the carbonylation of the corresponding copper(I)-acetonitrile complexes, [Cu(H2CPz2')(MeCN)](ClO4) (1) and [{Cu(H2CPz2')(MeCN)}2(mu-pyrazine)](ClO4)2 (2). Alternatively, treatment of mononuclear 1 and 3, respectively, with pyrazine in a molar ratio of 2:1 produces the pyrazine-bridged dinuclear Cu(I) complexes 2 and 4. Each of the complexes 1-4 can react with PPh3 to generate a common three-coordinated copper(I) complex [Cu(PPh3)(H2CPz2')](ClO4) (5). The structures of complexes 1-5 were all confirmed by X-ray crystallography. Comparison of the Cu(I)-C(CO) bond distances and the CO stretching frequencies of 3 and 4 indicates the back-donating properties of d pi(Cu)-pi*(pyrazine) bonds in 4, and accordingly, stabilizes the mixed-valence species generated from 2. Complex 3, stabilized by the strong interaction between copper(I) ion and perchlorate counteranion (Cu(I)-O(ClO4) = 2.240(3) A), is a potential precursor for polynuclear copper(I) carbonyl complexes.

Copper(I) complexes of fluorinated triazapentadienyl ligands: synthesis and characterization of [N[(C3F7)C(Dipp)N]2]CuL (where L = NCCH3, CNBut, CO; Dipp = 2,6-diisopropylphenyl).

Sterically demanding triazapentadiene [N[(C3F7)C(Dipp)N]2] H has been synthesized in good yield. It features a W-shaped ligand backbone in the solid state. [N[(C3F7)C(Dipp)N]2]H reacts with copper(I) oxide in acetonitrile leading to [N[(C3F7)C(Dipp)N]2]CuNCCH3. This copper adduct serves as an excellent precursor to obtain thermally stable [N[(C3F7)C(Dipp)N]2]CuCNBut and [N[(C3F7)C(Dipp)N]2]CuCO. IR spectroscopic data of these copper(I) isocyanide (CN = 2176 cm(-1)) and copper(I) carbonyl (CO = 2109 cm(-1)) complexes indicate that the [N[(C3F7)C(Dipp)N]2]- ligand is a fairly weak donor.

Calculations of Site-Specific CO Stretching Frequencies for Copper Carbonyls with the “Near Spectroscopic Accuracy”: CO Interaction with Cu+/MFI

A scaling method based on the linear correlation between the CO bond length and the CO stretching frequency has been applied to the CO molecule adsorbed on the Cu-exchanged MFI zeolite. Effects of anharmonicity, cluster size, unit cell size, and the Madelung potential were investigated. Interaction of CO with zeolite framework was described at the combined RI−BLYP/IPF level. The inner part of the combined model (RI−BLYP description) consisted of up to 23 TO4 tetrahedra. The effect of the Madelung potential on CO stretching frequencies was negligible. All Cu+ sites on the channel intersection and on the wall of the main channel are characterized by the CO stretching frequencies in the narrow range of 2159−2164 cm-1 in excellent agreement with experimental data. The Cu+ sites on the wall of the zigzag channel show slightly higher frequencies (3−6 cm-1). These sites are populated, however, only when the framework Al atoms are at T4 or T10 positions. The proposed computational scheme provides essentially the same level of accuracy as obtained from CCSD(T) calculations for small copper carbonyl species with overall error smaller than 5 cm-1.

Copper(I) Complexes of a Heavily Fluorinated β-Diketiminate Ligand: Synthesis, Electronic Properties, and Intramolecular Aerobic Hydroxylation

The aza-Wittig reaction between Ar(f)()-N=PPh(3) [Ar(f)() = 3,5-(CF(3))(2)C(6)H(3)] and 1,1,1,5,5,5-hexafluoro-2,4-pentanedione affords a new, highly fluorinated beta-diketimine, 1. Metalation by mesitylcopper(I) in benzene gives rise to the Cu(I) beta-diketiminate as its eta(2)-benzene adduct, 2a. Copper(I) carbonyl complexes of 1, and of three less-fluorinated analogues, have been generated in situ and compared by IR spectroscopy; the two backbone CF(3) groups exert a stronger electronic influence than the four N-aryl CF(3) groups. Dinuclear adduct 2b reacts readily with O(2), leading to ortho-hydroxylation of a ligand N-Ar(f)() group.

Sulfate and CO surface complexes formation with upd copper on Pd(111) and Pt(111) electrode surfaces: abnormal vibrational frequency shifts of CO and sulfate during upd processes

Carbon monoxide (CO) and sulfuric acid anion contacted with underpotential deposition (upd) copper on Pd(111) and Pt(111) electrode surfaces in 0.5 M H 2SO 4 solution were studied by cyclic voltammetry (CV) and in situ infrared reflection absorption spectroscopy (IRAS). CO was stabilized on copper covered Pd(111) and Pt(111) electrode surfaces. Both CO and (bi)sulfate molecules that were stabilized with copper, showed no potential dependent frequency shift in band center position over a certain potential range. Copper (bi)sulfate or copper carbonyl surface metal complexes are formed on Pd(111) and Pt(111) electrode surfaces in the potential range. The copper atoms in the upd potential range on Pd(111) or Pt(111) electrode do not form an ordinal metal ds band structure, but exhibit insulator like characteristics, due to excess positive charge of copper and ionic pseudo-copper metal complex formation on the surface.

Density functional investigation on copper carbonyl complexes

The structure and bonding of copper carbonyl complexes, [Cu(CO) n] 0/+/−, have been investigated at density functional levels of theory. It was found that the bond parameters and CO bond dissociation energy are very sensitive to the size of the employed basis set. The best agreement between theory and the available experimental data has been achieved at the B3LYP level with the cc-pVTZ/TZV2P basis set.

Tris(pyrazolyl)methanesulfonates: More Than Just Analogues of Tris(pyrazolyl)borate Ligands; N,N,N‐, N,N,O‐, and Other Coordination Modes

AbstractThe thallium(I) salts of tris(pyrazolyl)methanesulfonate (Tpms) and tris(3‐tert‐butylpyrazolyl)methanesulfonate (TpmstBu) have been used to prepare the following complexes: [(TpmstBu)ZnX] [X = Cl (1a), Br (1b), I (1c), Et (3), OAc (5a)], [(TpmstBu)NiX] [X = Cl (2a), Br (2b)], [(TpmstBu)CoCl(HpztBu)] (3), [(TpmstBu)Zn(μ‐OAc)(μ‐OH)Zn(TpmstBu)] (5b), [(TpmstBu)Cu(CO)] (6a), and [(Tpms)Cu(CO)] (6b). The solid‐state structures of 1b, 2a, 3, and 5b have been determined by X‐ray analysis. The optical spectra of 2a and 3 were investigated by means of the angular overlap model to elucidate their electronic structures in view of the underlying molecular geometries. Variable‐temperature NMR and IR spectroscopic studies show that Tpms and TpmstBu can act as N,N,N and N,N,O ligands. Both coordination modes are present in solution for the zinc complexes 1a,b and the copper carbonyl complexes 6a,b. The N,N,O bonding mode is entropically favoured in solution. For the nickel complexes 2a,b, the TpmstBu ligand acts as a tripodal nitrogen ligand in the solid state and in solution. For the dinuclear zinc complex 5b, one of the TpmstBu ligands acts as an N,N,O ligand and one as an N,O ligand. Complex 5b is one of the very few structural models of the dinuclear zinc enzymes phospholipase C and phosphotriesterase. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Infrared spectra and density functional calculations of the copper thiocarbonyls: CuCS, Cu(CS)2, and Cu2CS in solid argon

Microwave discharge through CS2 vapor yielded CS which was cocondensed with laser-ablated copper atoms at 12 K in an argon matrix. Binary copper thiocarbonyl complexes: CuCS, Cu(CS)2, and Cu2CS were formed via the reactions of ground state copper atoms or dimers with CS in solid argon. On the basis of isotopic shifts and splittings as well as density functional calculations, absorptions at 1187.2, 1291.3, and 1353.9 cm−1 are assigned to the C–S stretching vibrations of the bent CuCS, linear Cu(CS)2, and end-on bonded Cu2CS molecules, respectively. The calculation results show that these copper thiocarbonyl complexes are more strongly bonded than the corresponding copper carbonyl complexes.