Electron excitation coefficients of neutral and ionic levels of krypton in Townsend discharges

In this paper, we present experimental results for excitation coefficients of krypton atoms to several Kr and Kr⁺ excited levels for E/N (electric field to gas particle number density ratio usually in units of Townsend, 1 Td = 10^− 21 V m²) values from 7 × 10^− 20 V m² to above 1 × 10^− 17 V m². The data have been obtained in two different parallel plate self-sustained Townsend discharge drift tubes. The spatial distribution of the emission intensities were recorded and then normalized to give excitation coefficients at the anode, by using the electron flux at this point. The values of these coefficients are placed on an absolute scale by using a standard tungsten ribbon lamp calibrated against a primary blackbody radiation standard. The ionization rates at different E/N are obtained from the spatial emission profiles.The data for atomic krypton levels 2p₂, 2p₃, 2p₅, 2p₆, 2p₇, 2p₈, 3p₅ and 3p₆ (in Paschen notation) were converted to excitation coefficients by using quenching coefficients from the literature. The emission coefficients of eight 4s²4p⁴ (³P)5p levels of Kr⁺ have also been measured for E/N values from about 1 × 10^− 18 V m² up to nearly 8 × 10^− 18 V m².     

Real structure of SrSi2O2N2

SrSi₂O₂N₂ is an important host lattice for Eu²⁺ doped phosphors. Its crystal structure (space group P1, a = 7.0802(2) Å, b = 7.2306(2) Å, c = 7.2554(2) Å, α = 88.767(3)°, β = 84.733(2)°, γ = 75.905(2)° and V = 358.73(2) Å³, Z = 4) is isotypic with EuSi₂O₂N₂: highly condensed silicate layers are separated by Sr²⁺. The samples are characterized by pronounced real structure effects owing to pseudosymmetry of partial structures. Polysynthetic twinning with domains of various sizes is ubiquitous and oriented intergrowth of domains with different orientations has also been observed and analysed in detail by means of electron diffraction and high-resolution electron microscopy. These effects also affect the X-ray powder pattern and were taken into account in a Rietveld refinement.     

Novel poly (neutral red) nanowires as a sensitive electrochemical biosensing platform for hydrogen peroxide determination

Poly (neutral red) nanowires (PNRNWs) have been synthesized for the first time by the method of cyclic voltammetric electrodeposition using porous anodic aluminum oxide (AAO) template and were examined by scanning electron microscopy (SEM) and transmission electron microscope (TEM). Moreover, horseradish peroxidase (HRP) was encapsulated in situ in PNRNWs (denoted as PNRNWs–HRP) by electrochemical copolymerization for potential biosensor applications. The PNRNWs showed excellent efficiency of electron transfer between the HRP and the glassy carbon (GC) electrode for the reduction of H₂O₂ and the PNRNWs–HRP modified GC electrode showed to be excellent amperometric sensors for H₂O₂ at −0.1 V with a linear response range of 1 μM to 8 mM with a correlation coefficient of 0.996. The detection limit (S/N = 3) and the response time were determined to be 1 μM and <5 s and the high sensitivity is up to 318 μA mM⁻¹ cm⁻².     

Synthesis and crystal structure of the first chain-type nitridosilicates RE5Si3N9 (RE = La,Ce)

The novel branched chain-type nitridosilicates Ce₅Si₃N₉ and La₅Si₃N₉ have been synthesized in a radio-frequency furnace starting from the respective metals and silicon diimide Si(NH)₂ at 1625 °C for La₅Si₃N₉ and 1650 °C for Ce₅Si₃N₉, respectively. The structure of Ce₅Si₃N₉ has been determined by single-crystal X-ray diffraction (Ce₅Si₃N₉, Cmca (no. 64), a = 10.567(2) Å, b = 11.329(2) Å, c = 15.865(3) Å, V = 1899.3 Å³, Z = 8, R₁ = 0.0391, 1480 independent reflections, 90 refined parameters). The structure of isotypic La₅Si₃N₉ has been refined by the Rietveld method, starting from single-crystal data of Ce₅Si₃N₉ (La₅Si₃N₉, Cmca (no. 64), a = 10.647(4) Å, b = 11.414(4) Å, c = 16.030(5) Å, V = 1948.1 Å³, Z = 8, R_P = 0.0348, R_F² = 0.0533). Both compounds are built up of alternating Q²- and Q³-type corner sharing SiN₄ tetrahedra with additional corner sharing Q¹-units attached to the Q³-tetrahedra pointing alternately in opposing directions. These zipper-like chains are intertwined in both directions perpendicular to the chain itself to form a three-dimensionally interlocked structure with the rare-earth ions situated between the chains. Magnetic measurements resulted in a ferromagnetic ground state with a magnetic moment in agreement with Ce³⁺.     

Isopiestic determination of the osmotic and activity coefficients of dilute aqueous solutions of symmetrical and unsymmetrical quaternary ammonium bromides with a new isopiestic cell at 298.15 K

The osmotic coefficients of Bu₄NBr, sec-Bu₄NBr, iso-Bu₄NBr, Bu₂Et₂NBr and Bu₃EtNBr were determined by isopiestic method at 298.15 K in dilute aqueous solutions. A branched isopiestic cell was used. The osmotic coefficients of tetra-alkyl-ammonium solutions were analyzed comparing these with the Debye–Hückel limiting law. The order of the osmotic coefficient variation is Bu²Et₂N⁺ > BuEt₃N⁺ > sec-Bu₄N⁺ > iso-Bu₄N⁺ > n-Bu₄N⁺. The results were fitted to the Pitzer equation and the parameters β₀ and β₁ were calculated. The results are discussed.     

Structure elucidation of BaSi2O2N2 – A host lattice for rare-earth doped luminescent materials in phosphor-converted (pc)-LEDs

BaSi₂O₂N₂ is a promising host lattice for rare-earth doped luminescent materials in phosphor-converted (pc)-LEDs. Applying a combined approach, its orthorhombic average structure (space group Cmcm (no. 63), a = 14.3902(3) Å, b = 5.3433(1) Å, c = 4.83256(7) Å and V = 371.58(2) Å³, Z = 4) has been elucidated by electron diffraction and structure solution from X-ray and neutron powder diffraction data with subsequent Rietveld refinement (wRp = 0.0491 for X-ray data). The structure contains layers of highly condensed SiON₃ tetrahedra with O terminally bound to Si. The Ba²⁺ ions are situated between the layers and are surrounded by a cuboid of O atoms capped by two N atoms. In the structure, there is only one Ba site and one Si site, respectively, which is in accordance with a single sharp ²⁹Si NMR signal observed at ?52.8 ppm typical for SiON₃ tetrahedra in MSi₂O₂N₂ type oxonitridosilicates. Lattice energy calculations support the results of the structure determination.     

Modeling of thermal and chemical non-equilibrium in a laser-induced aluminum plasma by means of a Collisional-Radiative model

A 0D numerical approach including a Collisional-Radiative model is elaborated in the purpose of describing the behavior of the nascent plasma resulting from the interaction between a 4 ns/65 mJ/532 nm Q-switched Nd:YAG laser pulse and an aluminum sample in vacuum. The heavy species considered are Al, Al⁺, Al²⁺ and Al³⁺ on their different excited states and free electrons. The translation temperatures of free electrons and heavy species are assumed different (T_e and T_A respectively). Numerous elementary processes are accounted for as electron impact induced excitation and ionization, elastic collisions, multiphoton ionization and inverse Bremsstrahlung. Atoms passing from the sample to gas phase are described by using classical vaporization theory so that the surface temperature is arbitrarily limited to values less than the critical point one at 6700 K. The laser flux density considered in the study is therefore moderate with a fluence lower than 7 J cm^? 2.This model puts forward the major influence of multiphoton ionization in the plasma formation, whereas inverse Bremsstrahlung turns out to be quasi negligible. The increase of electron temperature is mainly due to multiphoton ionization and T_e does not exceed 10,000 K. The electron induced collisions play an important role during the subsequent phase which corresponds to the relaxation of the excited states toward Boltzmann equilibrium. The electron density reaches its maximum during the laser pulse with a value ≈ 10²², 10²³ m^? 3 depending highly on the sample temperature. The ionization degree is of some percents in our conditions.     

Uranium(VI) bis(imido) disulfonamide and dihalide complexes: Synthesis density functional theory analysis

Novel cis- and trans-bis(imido) uranium disulfonamide derivatives have been prepared from iodide metathesis reactions between two equivalents of K[N(Me)(SO₂Ar’)] (Ar’ = 4-Me-C₆H₄) and U(N^tBu)₂(I)₂(L)_x (L = OPPh₃, x = 2; Me₂bpy, x = 1; Me₂bpy = 4,4’-dimethyl-2,2’-bipyridyl). These bis(amide) derivatives serve as useful precursors for the synthesis of the trans-diphenolate complex U(N^tBu)₂(O-2-^tBuC₆H₄)₂(OPPh₃)₂ (5), cis- and trans-dithiolate complexes U(N^tBu)₂(SPh)₂(L)_x (L = OPPh₃ (6); Me₂bpy (7)), and cis- and trans-dihalide complexes with the general formulas U(N^tBu)₂(X)₂(L)_x (X = Cl, L = OPPh₃ (8), L = Me₂bpy (10); X = Br, L = OPPh₃ (9), L = Me₂bpy (11)). DFT calculations performed on the trans-dihalide series U(N^tBu)₂(X)₂(L)₂ and the UO₂²⁺ analogues UO₂X₂(OPPh₃)₂ suggest that the uranium centers in the [U(N^tBu)₂]²⁺ ions possess more covalent character than analogous UO₂²⁺ derivatives but that the U-X bonds in the U(N^tBu)₂X₂L₂ complexes possess a more ionic nature.     

Atomic and molecular emissions in laser-induced breakdown spectroscopy

This article summarizes measurements and analysis of hydrogen Balmer series atomic lines following laser-induced optical breakdown. Electron number density on the order of 1 × 10²⁵ m^− 3 can be measured using H_α Stark width and shift in the analysis of breakdown plasma in 1 to 1.3 × 10⁵ Pa, gaseous hydrogen. The H_β line can be utilized for electron number density up to 7 × 10²³ m^− 3. The historic significance is elaborated of accurate H_β measurements. Electron excitation temperature is inferred utilizing Boltzmann plot techniques that include H_γ atomic lines and further members of the Balmer series. Laser ablation of aluminum is discussed in view of limits of application of the Balmer series. H_β and H_γ lines show presence of molecular carbon in a 2.7 and 6.5 × 10⁵ Pa, expanding methane flow. Diagnostic of such diatomic emission spectra is discussed as well. Laser-induced breakdown spectroscopy historically embraces elemental analysis, or atomic spectroscopy, and to a lesser extent molecular spectroscopy. Yet occurrence of superposition spectra in the plasma decay due to recombination or due to onset of chemical reactions necessitates consideration of both atomic and molecular emissions following laser-induced optical breakdown. Molecular excitation temperature is determined using so-called modified Boltzmann plots and fitting of spectra from selected molecular transitions. The primary interest is micro-plasma characterization during the first few micro-seconds following optical breakdown, including shadowgraph visualizations.     

Organo-aluminum,zinc and magnesium derivatives of the imidotris(amido)phosphate Me3SiNP(NHtBu)3

Reactions of (^tBuHN)₃PNSiMe₃ (1) with the alkyl-metal reagents dimethylzinc, trimethylaluminum and di-n-butylmagnesium yield the monodeprotonated complexes [MeZn{(N^tBu)(NSiMe₃)P(NH^tBu)₂}] (2), [Me₂Al{(N^tBu)(NSiMe₃)P(NH^tBu)₂}] (3) and [Mg{(N^tBu)(NSiMe₃)P(NH^tBu)₂}₂] (4), respectively. Attempts to further deprotonate complex 2 with n-butyllithium or di-n-butylmagnesium result in nucleophilic displacement of the methylzinc fragment by lithium or magnesium. The two remaining amino protons of 3 are removed by reaction with di-n-butylmagnesium to give a heterobimetallic complex in which the coordination sphere of magnesium is completed by two molecules of THF (5 · 2THF) or one molecule of TMEDA (5 · TMEDA). Reaction of complex 3 with 1 equiv. of n-butyllithium followed by treatment of the product with di-n-butylmagnesium yields the complex {Me₂Al[(N^tBu)(NSiMe₃)P(N^tBu)₂]MgBu} Li · 4THF (6 · 4THF), the first example of a triply deprotonated complex of 1 containing three different metals. Reaction of complex 5 with iodine results in cleavage of an Al–Me group to give {MeIAl[(N^tBu)(NSiMe₃)P(N^tBu)₂Mg]} (7). Complexes 5 · 2THF, 5 · TMEDA, 6 · 4THF and 7 have been characterized in solution by multinuclear (¹H, ¹³C, ³¹P and ⁷Li) NMR spectroscopy, while the solid-state structures of 2, 4 and 5 · 2THF have been determined by X-ray crystallography.     

Radiolytic degradation of 4-nitrophenol in aqueous solutions: Pulse and steady state radiolysis study

The radiation induced degradation of 4-nitrophenol (4-NP) has been studied by gamma irradiation, while the reactivity and spectral features of the short lived transients formed by reaction with primary transient radicals at different pHs has been investigated by pulse radiolysis technique. In steady state radiolysis a dose of 4.4 k Gy is able to degrade 98% of 1×10⁻⁴ mol dm⁻³ 4-NP. 4-NP has pK_a at 7.1, above which it is present in the anionic form. At pH 5.2, ^•OH and N₃^• radicals were found to react with 4-NP with rate constants of 4.1×10⁹ dm³ mol⁻¹ s⁻¹ and 2.8×10⁸ dm³ mol⁻¹ s⁻¹, respectively. Differences in the absorption spectra of species formed in the reactions of 4-NP with ^•OH and N₃^• radicals suggested that ^•OH radicals add to the aromatic ring of 4-NP along with electron transfer reaction, whereas N₃^• radicals undergo only electron transfer reaction. At pH 9.2, rate constants for the reaction of ^•OH radicals with 4-NP was found to be higher by a factor of 2 compared to that at pH 5.2. This has been assigned to the deprotonation of 4-NP at pH 9.2.     

Experimental thermochemical study of the enthalpies of formation and sublimation of isonicotinamide,picolinamide, nicotinamide,isonicotinamideN-oxide,and nicotinamideN-oxide. The dissociation enthalpies of the N–O bonds

The standard (p ^∘  =  0.1MPa) molar enthalpies of combustion in oxygen, at T =  298.15 K, for crystalline picolinamide (2-NH₂COPy), nicotinamide (3-NH₂COPy), isonicotinamide (4-NH₂COPy), nicotinamide N -oxide (3- NH₂COPyNO), and isonicotinamide N - oxide (4-NH₂COPyNO) were measured by static-bomb calorimetry. These values were used to derive the standard molar enthalpies of formation of the crystalline compounds. The standard molar enthalpies of sublimation, at T =  298.15 K, for the three pyridinecarboxamide isomers were measured by microcalorimetry and the standard molar enthalpies of sublimation for the two pyridinecarboxamide N -oxide compounds were measured by a mass-loss effusion technique. From the enthalpies of formation of the gaseous compounds, the molar dissociation enthalpies D_m^oof the (N ⁺ – O ⁻ ) covalent bonds were derived. Comparison has been made with D_m^o(N–O) values in pyridine N -oxide derivatives.     

ATP- and redox-induced conformational changes in the activator of the radical enzyme 2-hydroxyisocaproyl-CoA dehydratase

A [4Fe–4S]¹⁺ cluster-containing protein activates 2-hydroxyisocaproyl-CoA dehydratase by an ATP-driven electron transfer. The activator has been proposed to change its conformation by MgATP similarly to nitrogenase Fe-protein. Iron chelation by bathophenanthroline removed the reduced [4Fe–4S]¹⁺ cluster from the activator in an ATP-dependent manner (rate, v = 0.128 ± 0.004 min⁻¹; K_m = 21 ± 1 μM); with ADP no chelation was observed (v < 0.001 min⁻¹). Chelation of the oxidised [4Fe–4S]²⁺ cluster occurred faster with ADP (v = 0.34 ± 0.05 min⁻¹) than with ATP (v = 0.132 ± 0.005 min⁻¹). The data indicate that reduction of the activator and binding of ATP induce conformational changes necessary to transfer the electron to the dehydratase. Interaction of both proteins promotes ATP hydrolysis (K_m = 0.5 ± 0.1 μM).     

Carbazole-modified blue light-emitting copolymers with the backbones integrated by diphenyloxadiazole,fluorene, and triphenylamine

Two new blue light-emitting polymers, poly{[2,5-bis(4-phenylene)-1,3,4-oxadiazole]-[9,9-dihexylfluorene-2,7-diyl]-[N-(4-(9H-carbazol-9-yl)phenyl)-N,N-bis(p-phenylene)aniline]} (POFPA) and poly{[2,5-bis(4-phenylene)-1,3,4-oxadiazole]-[9,9-dihexylfluorene-2,7-diyl]-[4-(3,6-(di-9H-carbazol-9-yl)-9H-carbazol-9-yl)-N,N-bis(p-phenylene)-aniline]} (POFCPA), were synthesized by Suzuki coupling reactions. By GPC analysis against a linear polystyrene standard POFPA and POFCPA were found to have M_n of 1.68 × 10⁴ and 3.70 × 10³, respectively. In contrast to POFPA, the main absorption peak of POFCPA in dilute toluene solution was blue-shifted by Δλ = 26 nm owing to its backbone of relatively shorter π-conjugation length and more carbazole units in side chain. The absolute fluorescence quantum yield (Φ_f) of POFCPA in dilute toluene solution was determined as 73%, much higher than that of POFPA (Φ_f ≈ 58.9%) measured under the same conditions. An electroluminescence device based on POFCPA displays a stable blue emission having color coordinates of (0.15, 0.20), a maximum brightness of 4762 cd/m², and a maximum current efficiency of 1.79 cd/A. By using this polymer as the host material doped with 1 wt.% 4,4′-bis[2-(4-(N,N-diphenylamino)phenyl)vinyl]biphenyl, the achieved highest brightness, maximum current efficiency and maximum power efficiency are 13,613 cd/m², 3.38 cd/A, and1.84 lm/W, respectively.     

Enhanced electrochemical performance of carbon-coated TiO2 nanobarbed fibers as anode material for lithium-ion batteries

We report the electrochemical performance of carbon-coated TiO₂ nanobarbed fibers (TiO₂@C NBFs) as anode material for lithium-ion batteries. The TiO₂@C NBFs are composed of TiO₂ nanorods grown on TiO₂ nanofibers as a core, coated with a carbon shell. These nanostructures form a conductive network showing high capacity and C-rate performance due to fast lithium-ion diffusion and effective electron transfer. The TiO₂@C NBFs show a specific reversible capacity of approximately 170 mAh g^− 1 after 200 cycles at a 0.5 A g^− 1 current density, and exhibit a discharge rate capability of 4 A g^− 1 while retaining a capacity of about 70 mAh g^− 1. The uniformly coated amorphous carbon layer plays an important role to improve the electrical conductivity during the lithiation–delithiation process.     

Dissociative electron attachment to polyatomic molecules: Ion kinetic energy measurements

Dissociative electron attachment to SO₂, NO₂, NF₃ and H₂O₂ is studied in terms of the kinetic energies of the dominant fragment ions. The O^? data from SO₂ show that the two major resonances at 4.6 and 7.2 eV respectively have the same dissociation limit. Similarly, the resonances at 1.8 and 3.5 eV in the O^? channel in NO₂ appear to have same dissociation limit of NO (X ²Π) + O^?, while the resonance at 8.5 eV appears to dissociate to give NO (a ⁴Π_i) along with O^?. We find considerable internal excitation of the neutral fragments in all these cases along with that of NF₃, whereas the negative ion resonance in H₂O₂ appears to fragment almost like a diatomic system with very little internal excitation of the OH and OH^? fragments.     

Thermochemistry of Cu(II) and Ni(II) complexes with N,N-di-n-butyl-N′-thenoylthiourea and N,N-di-iso-butyl-N′-thenoylthiourea

Two substituted N-acylthioureas and the respective Ni(II) and Cu(II) complexes were synthesized, namely: N,N-di-n-butyl-N′-thenoylthiourea (Hnbtu); N,N-di-iso-butyl-N′-thenoylthiourea (Hibtu); bis[N,N-di-n-butyl-N′-thenoylthioureato]nickel(II), [Ni(nbtu)₂]; bis[N,N-di-n-butyl-N′-thenoylthioureato]copper(II), [Cu(nbtu)₂]; bis[N,N-di-iso-butyl-N′-thenoylthioureato]nickel(II), [Ni(ibtu)₂]; bis[N,N-di-iso-butyl-N′-thenoylthioureato]copper(II), [Cu(ibtu)₂]. The standard (p^° = 0.1 MPa) molar enthalpies of formation and sublimation of the two N-acylthioureas were measured, at T = 298.15 K, by rotating-bomb combustion calorimetry and Calvet microcalorimetry, respectively. The standard (p^° = 0.1 MPa) molar enthalpies of formation of the Ni(II) and Cu(II) complexes were determined, at T = 298.15 K, by high precision solution–reaction calorimetry. From the results obtained, the enthalpies of hypothetical metal–ligand and metal–metal exchange reactions, in the gaseous phase, were derived, thus allowing a discussion of the gaseous phase energetic difference between the complexation of Ni(II) and Cu(II) to 1,3-ligand systems with (S,O) ligator atoms.     

Thermodynamics and kinetics of adsorption of Cu(II) from aqueous solutions onto a new cation exchanger derived from tamarind fruit shell

A novel cation exchanger (TFS-CE) having carboxylate functionality was prepared through graft copolymerization of hydroxyethylmethacrylate onto tamarind fruit shell (TFS) in the presence of N,N′-methylenebisacrylamide as a cross-linking agent using K₂S₂O₈/Na₂S₂O₃ initiator system, followed by functionalisation. The TFS-CE was used for the removal of Cu(II) from aqueous solutions. At fixed solid/solution ratio the various factors affecting adsorption such as pH, initial concentration, contact time, and temperature were investigated. Kinetic experiments showed that the amount of Cu(II) adsorbed increased with increase in Cu(II) concentration and equilibrium was attained at 1 h. The kinetics of adsorption follows pseudo-second-order model and the rate constant increases with increase in temperature indicating endothermic nature of adsorption. The Arrhenius and Eyring equations were used to obtain the kinetic parameters such as activation energy (E_a) and enthalpy (ΔH^#), entropy (ΔS^#) and free energy (ΔG^#) of activation for the adsorption process. The value of E_a for adsorption was found to be 10.84 kJ · mol^?1 and the adsorption involves diffusion controlled process. The equilibrium data were well fitted to the Langmuir isotherm. The maximum adsorption capacity for Cu(II) was 64 · 10 mg · g^?1 at T = 303 K. The thermodynamic parameters such as changes in free energy (ΔG^°), enthalpy (ΔH^°), and entropy (ΔS^°) were derived to predict the nature of adsorption process. The isosteric heat of adsorption increases with increase in surface loading indicating some lateral interactions between the adsorbed metal ions.     

Magneto-structural correlation and low temperature heat capacity of a Mn (III) quadridentate Schiff-base coordination compound

A new Mn (III) Schiff-base coordination compound, [Mn(L)(NCS)]₂ (H₂L = N,N′-bis(5-chlorosalicylidene)-1,2-diaminoethane), has been synthesized and characterized structurally and magnetically. The target compound is a phenoxo-bridged dimeric compound with the isothiocyanate coordinating in a usual bent mode. A magnetic susceptibility study reveals that the target compound exhibits antiferromagnetic intra-dimer coupling between Mn (III) ions. The low temperature heat capacity of the compound over the temperature range (2 to 300) K has been measured using the heat capacity option of a Quantum Design Physical Property Measurement System (PPMS). The thermodynamic functions in the experimental temperature range have been determined by curve fitting. The standard entropy and enthalpy of the as-prepared compound at T = 298.15 K have been calculated to be (924.52 ± 10.17) J · K⁻¹ · mol⁻¹ and (133.47 ± 1.47) kJ · mol⁻¹, respectively.     

Synthesis of (NHC)Rh(cod)Cl and (NHC)RhCl(CO)2 complexes – Translation of the Rh- into the Ir-scale for the electronic properties of NHC ligands

Twenty-three different Rh complexes of the (NHC)RhCl(cod) and (NHC)RhCl(CO)₂ type were synthesized from [RhCl(cod)]₂. The electron donating nature of the NHC ligands was changed in a systematic manner. The redox potentials of the various (NHC)RhCl(cod) and the ν(CO) of the various (NHC)RhCl(CO)₂ were determined. A correlation of the Rh redox potentials and the Rh ν(CO), respectively, with the related data from analogous (NHC)IrCl(cod) and (NHC)IrCl(CO)₂ complexes established two linear relationships. The linear regression (R² = 0.993) of the Rh and the Ir redox potentials results in an equation for the redox potential transformation: E_1/2(Ir) = 1.016 · E_1/2(Rh) ? 0.076 V. The linear regression (R² = 0.97) of the Rh and Ir ν_av(CO) results in an equation for the ν_av(CO) transformation: ν_av(CO)Ir = 0.8695 · ν_av(CO)Rh + 250.7 cm^?1. In this manner the Rh and the Ir-scale for the determination of the electron donating properties of NHC ligands are unified.