Llewellyn H. Jones

SYSTEMATICS IN THE VIBRATIONAL SPECTRA OF URANYL COMPLEXES

Abstract The calculation of U-O bond force constants for uranyl complexes from their infra-red absorption spectra is discussed. The maximum error involved in treating the uranyl group as free UO 2 ++ for calculation of the U-O force constant is estimated to be less than 3 per cent. Approximate anharmonicity constants for general use for the uranyl vibrations are given. The application of Badgers rule relating U-O force constant to U-O bond distance is discussed.

Determination of U-O bond distance in uranyl complexes from their infrared spectra*

Abstract From the U-O bond force constant and U-O bond distance in K 3 UO 2 F 5 the constant, d UO , has been calculated to use with Badgers rule. It is shown that this relation ( r UO = 1·08 F UO −1/3 + 1·17) gives good agreement when applied to NaUO 2 (Ac) 3 . R is in angstroms and F in mulidynes per angstrom. The other known cases (UO 2 CO 3 and MgUO 2 O 2 ) are in agreement, but the limits of error involved are too great to allow further confirmation of the relation. It is shown that the observation of the two vibrational frequencies, ν 3 and ν 1 + ν 3 , of the uranyl group, should serve as a very sensitive measure of the U-O bond distance.

Infrared Absorption Spectra of Aqueous HF2—, DF2—, and HF

Strong infrared absorption bands of KHF2 appear at 1233 cm—1 and 1473 cm—1 in the solid, and are observed at 1206 cm—1 and 1536 cm—1 respectively, in H2O solution. Corresponding values for KDF2 are 888 cm—1 and 1045 cm—1 in the solid, and 873 cm—1 and 1102 cm—1 in D2O solution. In saturated KHF2 and in KHF2 solutions containing excess HF, there appear new, broad absorption bands attributed to polymeric species, e.g., H2F3—. The HF2— ion is observed in concentrated aqueous HF; in addition, there is a strong absorption at 1820 cm—1 which is not shifted in D2O‐HF mixtures.

Potential Constants of Iron Pentacarbonyl from Vibrational Spectra of Isotopic Species

The vibrational spectra of Fe(12C16O)5, Fe(13C16O)5, and Fe(12C18O)5 have been observed. Most of the fundamentals have been assigned, with some changes from earlier results in the literature. Potential constants have been calculated by constraining many of the interaction constants to values estimated from analogous constants of the hexacarbonyls. The results indicate that the axial CO bonds are stronger than the equatorial CO bonds. This implies that the axial MC bonds are weaker than the equatorial MC bonds, though the calculated MC potential constants are not significantly different.

Infrared Spectrum and Structure of the Thiocyanate Ion

The infrared absorption spectra of aqueous and solid KNCS have been studied (the latter in detail) from 280–10 000 cm—1. The fundamental frequencies of NCS— in aqueous solution are v1 = 2066, v2 = 470, and v3 = 743 cm—1. In the solid, the degeneracy of the bending vibration is removed and four fundamentals are observed at 2053, 484, 470, and 749 cm—1, respectively. Many combination bands were observed for solid KNCS from which the anharmonicity constants and the frequencies for infinitesimal amplitudes of vibration were calculated. The fundamental frequencies of the C13 and S34 isotopic species were observed also. From the zero‐order frequencies, force constants were calculated for NCS— in KNCS as kN–C = 15.95 md/A, kC–S = 5.18 md/A, k12 = +0.9 md/A, and kα/RC–NRC–S = 0.311 and 0.300 md/A. With the use of Badgers rule the bond distances are calculated to be RN–C = 1.17 A, RC–S = 1.61 A. These distances indicate a considerable amount of double bond character in the C–S bond.

Infrared Spectra and Structure of Uranyl and Transuranium (V) and (VI) Ions in Aqueous Perchloric Acid Solution

Infrared spectra of aqueous solutions of U(VI), Np(VI), Pu(VI), and Am(VI) show conclusively that these ions exist as symmetrical and linear, or nearly linear, XO2++. The spectra of Np(V) and Am(V) show that they are probably XO2+ ions. Force constants and estimated distances are given for the X—O bonds. For the XO2++ series, the X—O force constant is expressed as a parabolic function of atomic number, with the maximum occurring at NpO2++. This is contrary to behavior expected if there were a regular contraction in ionic radii for the series XO2++.

Force constants of methane. Infrared spectra and thermodynamic functions of isotopic methanes

Abstract General quadratic valence force constants have been calculated for the symmetrical methanes ( CY 4 ) using the most recent experimental data. The F and G matrix elements are given for the isotopic species CY 3 Z and CY 2 Z 2 ( Y and Z are H, D, or T). The fundamental frequencies of CY 3 Z and CY 2 Z 2 were calculated using the CY 4 force constants. Most of the fundamental frequencies of these isotopic methanes were observed. The anharmonic corrections are discussed. From the force constants, zeta values were calculated for the degenerate vibrations of CY 3 Z . The thermodynamic quantities − (F 0 − E 0 0 ) T , (E 0 − E 0 0 ) T , S 0 , C p 0 , C p 0 , and equilibrium constants for the various H, D, and T isotope exchange equilibria are given at seven temperatures from −180°C to +1000°C.

Force Constants of Nickel Carbonyl from Vibrational Spectra of Isotopic Species

The infrared spectra of gaseous Ni(13CO)4 and Ni(C18O)4 and the infrared and Raman spectra of CCl4 solutions of these isotopic molecules were recorded. General quadratic valence force constants have been calculated from the frequencies of the normal species and the two isotopic species. The resulting force constant solution is similar to that obtained previously assuming a pi electron interaction potential function. These results put the force constants of metal carbonyls on a firmer basis.

Infrared Absorption Studies of Aqueous Complex Ions. II. Cyanide Complexes of Cu (I) in Aqueous Solution

In the system CuCN–KCN–H2O, we have observed infrared absorption spectra of three distinct complex ions: Cu(CN)2−,e=165±25 mole−1 liter cm−1 at 2125 cm−1;Cu(CN)3=,e=1090±10 mole−1 liter cm−1 at 2094 cm−1;andCu(CN)4≡,e=1657±15 mole−1 liter cm−1 at 2076 cm−1. At 29°C, the constants for the dissociation of Cu(CN)4≡ into Cu(CN)3=+CN— are: K4, 3c = 0.0076±0.0005 mole liter—1 [in terms of concentrations at 0.1—0.2f Cu(I)] and K4, 3a = 0.026 mole liter—1 (in terms of activities). Analogous values for the dissociation of Cu(CN)3= into Cu(CN)2—+CN— are K3, 2c = (2.44±0.36)×10—5 mole liter—1, and K3, 2a = 4.2×10—5. The above values are calculated from approximately 100 determinations. At 25°C, the corresponding values of these constants are approximately K4, 3c = 0.0057 and K3, 2c = 1.5×10—5.Using the activity constants determined in this paper and a value of 1×10—24 for the constant: [Cu+][CN—]2/[Cu(CN)2—] we derive the following values: [Cu+][CN—]3/[Cu(CN)3=] = 2.6×10—29 and [Cu+][CN—]4/[Cu(CN)4≡] = 5×10—31. The ...

Vibrational Spectra and Force Constants for Isotopic Species of Nitrosyl Chloride

From infrared absorption studies in the gaseous phase, fundamental harmonic vibrational frequencies have been determined for 16O14N35Cl, 16O15N35Cl, 18O14N35Cl, and 18O15N35Cl. With the aid of centrifugal‐distortion data from the literature, a unique general quadratic valence‐force‐constant solution was obtained. The resulting values are: FNO = 15.26 mdyn A−1, FNCl = 1.27 mdyn A−1, Fα = 1.32 mdyn A−1·rad−2, FNO,NCl = 1.53 mdyn A−1, FNO,α = 0.1 mdyn rad−1, FNCl,α = 0.12 mdyn rad−1.