Ionization potentials and electron affinities of Cu,Ag, and Au: Electron correlation and relativistic effects

The electron correlation and relativistic effects on ionization potentials and electron affinities of Cu, Ag, and Au are investigated in the framework of the coupled cluster method and different 1-component approximations to the relativistic Dirac-Coulomb Hamiltonian. The first-order perturbation approach based on the massvelocity and Darwin terms is found to be sufficiently accurate for Cu and Ag while it fails for Au. The spin-averaged Douglas-Kroll no-pair method gives excellent results for the studied atomic properties. The ionization potentials obtained within this method and the coupled cluster scheme for the electron correlation effects are 7.733(7.735) eV for Cu, 7.461(7.575) eV for Ag, and 9.123(9.225) eV for Au (experimental values given in parentheses). The calculated (experimental) electron affinity results for Cu, Ag, and Au are 1.236(1.226), 1.254(1.303), and 2.229(2.309) eV, respectively. There is a marked relativistic effect on both the ionization potential and electron affinity of Ag which sharply increases for Au while Cu exhibits only a little relativistic character. A similar pattern of relativistic effects is also observed for electric dipole polarizabilities of the coinage metal atoms and their ions. The coupled cluster dipole polarizabilities of the coinage metal atoms calculated in this article in the Douglas-Kroll no-pair formalism (Cu: 46.50 au; Ag: 52.46 au; Au: 36.06 au) are compared with our earlier data for their singly positive and singly negative ions. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 557–565, 1997     

Self-consistent relativistic effective core potentials for transition metal atoms: Cu,Ag, and Au

A development of the RECP method for the case of transition and rare earth elements is suggested. New terms with projectors on the occupation numbers ofd andf outermost shells respectively (which can be determined in SCF iterations) are added to the standard RECP operator and the corresponding self-consistent RECP terms are generated for atoms Cu, Ag and Au. Significant improvement is achieved in reproduction of atomic excitation energies as compared with the conventional shape-consistent RECP calculation.     

Core/valence partition and relativistic effects in effective potentials for transition metals

Two different versions, relativistic and nonrelativistic, of the “shape-consistent” effective potential (EP ) formalism are analyzed in ab initio calculations for transition metals. The influence of alternative core/valence partitions on the reliability of the procedure is discussed. The accuracy of EP results for transition metals is shown to depend on adequate choices of the valence subspace and proper inclusion of relativistic effects.     

Chemical Composition and Structure–Vacancy Disordering in Ag–Au,Cu–Au,Ag–Pd,and Cu–Pd Alloys as Factors of Their Electrocatalytic Activity

The oxalic acid electrooxidation kinetics is studied at polycrystalline electrodes of vacancy-disordered Au* and Pd* obtained by anodically modifying in 0.5 M H₂SO₄ the surface of Ag–Au, Cu–Au, Ag–Pd, and Cu–Pd alloys containing no less than 50 at. % of the noble metal. It is found that a qualitative correlation exists between variations in thermodynamic and electrocatalytic activities of both Au* and Pd* following a change in the surface concentration of vacancies in alloys of constant composition and in the volume concentration of the electronegative component in alloys with approximately identical concentrations of vacancies. Such a correlation may be due to the existence of some factor through which an anodically-modified alloy affects the electrocatalytic process. The factor, presumably the alloy's electronic structure, is more generic than the alloy's volume composition, the nature of components, and the vacancy concentration.     

Valent states of Cu,Ag, and Au atoms in molecules and solids are the same

Ratios between the distances, energies, and force constants of molecules (M₂) and corresponding solids (M) were shown to be approximately equal for elements of Groups 1a and 1b of the Periodic Table. It follows from elementary calculations that the different physical properties of these elements are determined by the electronic structure of isolated atoms, and there is no need to introduce the concepts and values of “metal” valences for Cu, Ag, and Au in solid state.     

Systematic trends in the radial matrix elements of E1 transitions in Li,F, Na and Cu isoelectronic sequences

Collision cross sections are calculated using the R-matrix method for excitations between the three lowest LS states for Na-like Cu ion. The complex resonance structures are investigated. The collision rate coefficients have been calculated assuming a Maxwellian distribution of electron-impact energies. The results of the collision cross sections are in good agreement with those of the other theory.     

Structure and bonding of the MCN molecules, M=Cu,Ag,Au,Rg

High-precision calculations are reported for the title series with M=Cu, Ag, Au, using CCSD(T) with the latest pseudopotentials and basis sets up to cc-pVQZ. The bond lengths for M=Cu, Ag, Au agree with experiment within better than 1 pm. The role of deep-core excitations is studied. The second-order spin-orbit effects are evaluated at the density functional theory level, including M=Rg. A qualitative bonding analysis suggests multiple M-C bonding. The calculated vibrational frequencies are expected to be more accurate than the available experimental estimates. The M-C bond lengths obey Cu相似文献   

Electrochemical CO2 reduction catalyzed by atomically precise alkynyl-protected Au7Ag8, Ag9Cu6, and Au2Ag8Cu5 nanoclusters: probing the effect of multi-metal core on selectivity

Doping metal nanoclusters (NCs) with another metal usually leads to superior catalytic performance toward CO₂ reduction reaction (CO₂RR), yet elucidating the metal core effect is still challenging. Herein, we report the systematic study of atomically precise alkynyl-protected Au₇Ag₈, Ag₉Cu₆, and Au₂Ag₈Cu₅ NCs toward CO₂RR. Au₂Ag₈Cu₅ prepared by a site-specific metal exchange approach from Ag₉Cu₆ is the first case of trimetallic superatom with full-alkynyl protection. The three M₁₅ clusters exhibited drastically different CO₂RR performance. Specifically, Au₇Ag₈ demonstrated high selectivity for CO formation in a wide voltage range (98.1% faradaic efficiency, FE, at −0.49 V and 89.0% FE at −1.20 V vs. RHE), while formation of formate becomes significant for Ag₉Cu₆ and Au₂Ag₈Cu₅ at more negative potentials. DFT calculations demonstrated that the exposed, undercoordinated metal atoms are the active sites and the hydride transfer as well as HCOO* stabilization on the Cu–Ag site plays a critical role in the formate formation. Our work shows that, tuning the metal centers of the ultrasmall metal NCs via metal exchange is very useful to probe the structure–selectivity relationships for CO₂RR.

We report the first all-alkynyl-protected Au₂Ag₈Cu₅ cluster, which adopts a M@M₈@M₆ core configuration similar with Au₇Ag₈/Ag₉Cu₆ clusters. The three clusters exhibited strong metal core effect toward CO₂RR, which was understood by DFT calculations.     

缺陷石墨烯吸附Au、Ag、Cu的第一性原理计算

采用基于密度泛函理论的投影缀加波方法研究了Au、Ag、Cu吸附在缺陷石墨烯单侧和双侧的体系,对吸附体系的吸附能、磁性、电荷转移和电子结构进行了计算和分析. 缺陷石墨烯吸附Au、Ag、Cu体系的吸附能比本征石墨烯增加2 eV以上,说明三种金属原子更容易吸附在缺陷位置;吸附体系的电荷密度差分和电子结构的结果表明,Au、Ag、Cu与缺陷石墨烯之间均为化学吸附. 计算吸附体系的磁性发现,单侧吸附时三种吸附体系均有磁性,磁矩大约为1μ_B;双侧吸附时,三种吸附体系磁矩大约为2μ_B.     

缺陷石墨烯吸附Au、Ag、Cu的第一性原理计算

采用基于密度泛函理论的投影缀加波方法研究了Au、Ag、Cu吸附在缺陷石墨烯单侧和双侧的体系,对吸附体系的吸附能、磁性、电荷转移和电子结构进行了计算和分析.缺陷石墨烯吸附Au、Ag、Cu体系的吸附能比本征石墨烯增加2 eV以上,说明三种金属原子更容易吸附在缺陷位置;吸附体系的电荷密度差分和电子结构的结果表明,Au、Ag、Cu与缺陷石墨烯之间均为化学吸附.计算吸附体系的磁性发现,单侧吸附时三种吸附体系均有磁性,磁矩大约为1μB;双侧吸附时,三种吸附体系磁矩大约为2μB.     

Benchmark calculations on the adiabatic ionization potentials of M-NH(3) (M=Na,Al,Ga,In,Cu,Ag)

The ground states of the M-NH(3) (M=Na,Al,Ga,In,Cu,Ag) complexes and their cations have been studied with density functional theory and coupled cluster [CCSD(T)] methods. The adiabatic ionization potentials (AIPs) of these complexes are calculated, and these are compared to results from high-resolution zero-electron kinetic energy photoelectron spectroscopy. By extrapolating the CCSD(T) energies to the complete basis set (CBS) limit and including the core-valence, scalar relativistic, spin-orbit, and zero-point corrections, the CCSD(T) method is shown to be able to predict the AIPs of these complexes to better than 6 meV or 0.15 kcal/mol. 27 exchange-correlation functionals, including one in the local density approximation, 13 in the generalized gradient approximation (GGA), and 13 with hybrid GGAs, were benchmarked in the calculations of the AIPs. The B1B95, mPW1PW91, B98, B97-1, PBE1PBE, O3LYP, TPSSh, and HCTH93 functionals give an average error of 0.1 eV for all the complexes studied, with the B98 functional alone yielding a maximum error of 0.1 eV. In addition, the calculated metal-ammonia harmonic stretching frequencies with the CCSD(T) method are in excellent agreement with their experimental values, whereas the B3LYP method tends to underestimate these stretching frequencies. The metal-ammonia binding energies were also calculated at the CCSD(T)/CBS level, and are in excellent agreement with the available experimental values considering the error limits, except for Ag-NH(3) and Ag(+)-NH(3), where the calculations predict stronger bond energies than measured by about 4 kcal/mol, just outside the experimental error bars of +/-3 kcal/mol.     

Theoretical designs for planar tetracoordinated carbon in Cu, Ag, and Au organometallic chemistry: a new target for synthesis

In the past 30 years, substantial efforts and progress have been made in the design and synthesis of molecules containing tetracoordinated planar carbon, by overcoming the inherent preference for tetrahedral bonding. As a result, we have studied 12 organometallic molecules containing group 11 elements (i.e., M-X; M = Cu, Ag, and Au and X = I, II, III, and IV) using density functional theory to determine whether the central carbon atom exists in a planar geometry. Our theoretical findings suggest that in such M-X species, bonding interactions between the central carbon and the coinage metal ligands and between the metal ligands (i.e., metallophilic attractions) are both important in favoring planar-tetracoordinated carbon compounds over the corresponding tetrahedral structures. The compounds studied in this work are seen as excellent targets for chemical synthesis.     

New potential-energy functions for Cu, Ag and Au solids and their applications to computer simulations on metallic surfaces

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Simple Synthetic Routes to Carbene-M-Amido (M=Cu,Ag, Au) Complexes for Luminescence and Photocatalysis Applications

The development of novel and operationally simple synthetic routes to carbene-metal-amido (CMA) complexes of copper, silver and gold relevant for photonic applications are reported. A mild base and sustainable solvents allow all reactions to be conducted in air and at room temperature, leading to high yields of the targeted compounds even on multigram scales. The effect of various mild bases on the N−H metallation was studied in silico and experimentally, while a mechanochemical, solvent-free synthetic approach was also developed. Our photophysical studies on [M(NHC)(Cbz)] (Cbz=carbazolyl) indicate that the occurrence of fluorescent or phosphorescent states is determined primarily by the metal, providing control over the excited state properties. Consequently, we demonstrate the potential of the new CMAs beyond luminescence applications by employing a selected CMA as a photocatalyst. The exemplified synthetic ease is expected to accelerate the applications of CMAs in photocatalysis and materials chemistry.     

The first ionization potentials and conjugation in benzene derivatives containing organosilicon, organogermanium, organotin, and organolead substituents

The inductive and resonance effects of silicon-, germanium-, tin-, and lead-containing and some organic substituents on the HOMO energies (E _HOMO) for 43 monosubstituted andp-disubstituted benzene derivatives were analyzed in the Koopmans approximation. A linear dependence between the perturbation energy δE and the resonanceσ _R ⁺ parameters of the substituents was established. The Koopmans approximation is a rough approximation for the compounds studied, since to provide for its rigorous fulfilment, the δE values must depend on the σ _R ⁰ parameters of the substituents. The principal regularities of increasing the σ,π-conjugation between the organoelement substituents and the π-system caused by a positive charge on the benzene ring were established. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 70–75, January 1997.     

Polymerization Isomerism in Co-M (M = Cu,Ag, Au) Carbonyl Clusters: Synthesis,Structures and Computational Investigation

The reaction of [Co(CO)₄]⁻ (1) with M(I) compounds (M = Cu, Ag, Au) was reinvestigated unraveling an unprecedented case of polymerization isomerism. Thus, as previously reported, the trinuclear clusters [M{Co(CO)₄}₂]⁻ (M = Cu, 2; Ag, 3; Au, 4) were obtained by reacting 1 with M(I) in a 2:1 molar ratio. Their molecular structures were corroborated by single-crystal X-ray diffraction (SC-XRD) on isomorphous [NEt₄][M{Co(CO)₄}₂] salts. [NEt₄](3)represented the first structural characterization of 3. More interestingly, changing the crystallization conditions of solutions of 3, the hexanuclear cluster [Ag₂{Co(CO)₄}₄]²⁻ (5) was obtained in the solid state instead of 3. Its molecular structure was determined by SC-XRD as Na₂(5)·C₄H₆O₂, [PPN]₂(5)·C₅H₁₂ (PPN = N(PPh₃)₂]⁺), [NBu₄]₂(5) and [NMe₄]₂(5) salts. 5 may be viewed as a dimer of 3 and, thus, it represents a rare case of polymerization isomerism (that is, two compounds having the same elemental composition but different molecular weights) in cluster chemistry. The phenomenon was further studied in solution by IR and ESI-MS measurements and theoretically investigated by computational methods. Both experimental evidence and density functional theory (DFT) calculations clearly pointed out that the dimerization process occurs in the solid state only in the case of Ag, whereas Cu and Au related species exist only as monomers.     

Mass spectrometry of steroid systems—XXI Appearance and ionization potentials for the stereo-isomers of the D-homoestrane series

The ionization potentials of methyl ethers of D-homoequilenine, its 14ß-isomer, D-homoestrone and its 8°-isomer, as well as appearance potentials of certain fragment ions have been determined by means of electron-impact. The dissociation energies of the bonds which are split in the course of formation of these ions have been calculated.