Distortion of the coordination polyhedron in mononuclear copper(II) complexes. Optical absorption and electron spin resonance studies on some five-coordinate copper(II) complexes

The preparation and spectral properties are reported for a series of ten mixed-ligand copper(II) complexes of the form [Cu(A)(B)_n](X), where A is acetylacetonate anion, B represents a mono- or bidentate ligand such as morpholine, piperidine, isonicotinic acid hydrazide, 2,2′-bipyridine, 1,10-phenanthroline and X is variously NO^?₃ or ClO^?₄ anion and n = 1 or 2. The coordination of the anions and ligands has been demonstrated by infrared and electronic spectral methods. Electron spin resonance spectral data show the square-pyramidal five-coordinated arrangement around copper(II) in these complexes. Parameters such as g₆, g_⊥, A₆, A_⊥, 〈g〉 and 〈A〉 calculated from electron spin resonance data in solid and solution state at room temperature as well as frozen solution indicate the presence of the unpaired electron in the d_x2_?y2 or d_z2 orbital. These results are in good agreement with electronic and photoacoustic spectral studies.     

Interaction of kerogen and mineral matrix of an oil shale in an oxidative atmosphere

The effects of the inorganic matrix of the oil shale on the oxidation of the kerogen at temperatures up to 1000°C in an air atmosphere were investigated Kerogen was isolated by successive HCl, HF and LiAlH₄ treatments. The initial shale and each product of every demineralization process were oxidized in a thermogravimetric system in an air atmosphere. The oxidation products were analyzed by Fourier transform infrared spectroscopy. Changes in the chemical structure of the organic material of the shale were correlated with the separated constituents of the inorganic matrix. Oxidation of the kerogen occurred in two stages. The first stage was complete at about 400°C. The oxidized product after the first stage contained a char of an aromatic ring system substituted with some aliphatic material and carbonyl groups. Calcium minerals increased the reactivity of the aromatic part of the organic material towards the oxidation reactions. Where calcium minerals were absent, mainly the aliphatic and the carbonyl groups decomposed. Silicates and pyrites did not affect the reactivity of the organic material in oxidation reactions.     

Far-infrared photoconductivity spectra of quenched-in acceptors in germanium: Chemical effects on the SA1 acceptors

Far-I.R. photoconductivity reveals the existence of at least four different kinds of SA₁ acceptors in germanium quenched from T > 800 each acceptor producing two or more hydrogenic excitation line series. One acceptor is correlated with the presence of Ni, another one with strong Cu contamination. The two other acceptors, which we call ‘normal’ and ‘shifted’, occur in samples quenched without intentional doping. The experiments indicate that the SA₁ acceptors in germanium are impurity complexes involving fast diffusing elements. We discuss a model according to which the SA₁ acceptors would be interstitial-substitutional pairs of transition metals. In particular, we propose to assign the ‘normal’ SA₁ acceptors to Fe_I-Cu_S pairs.     

Room-temperature phosphorescence of anilinonaphthalenesulfonate “fluorescence probe” compounds

2,6-anilinonaphthalenesulfonate (2,6-ANS) and 2,6-toluidinonaphthalenesulfonate (2,6-TNS) exhibit room-temperature phosphorescence when absorbed on filter paper, but the corresponding 1,8-isomers (1,8-ANS and 1,8-TNS) do not. The phosphorescence of the 2,6-isomers and nonphosphorescence of the 1,8-isomers is also found to hold in rigid glass at 77 K. No phosphorescence was detectable from N-phenyl-1-napthylamine at room temperature or 77 K, indicating that intramolecular hydrogen bonding in the 1,8-isomers isomers is not an essential feature inhibiting phosphorescence. Very effective heavy-atom enhancement of the phosphorescences of 2,6-ANS and 2,6-TNS by sodium iodide is observed.     

Correlations between ESCA chemical shifts and modified sanderson electronegativity calculations

Correlations are given between ESCA chemical shifts and partial atomic changes calculated by the modified Sanderson method. Elements included are boron, carbon, silicon, germanium, tin, nitrogen, phosphorus, arsenic, oxygen, sulfur, selenium, fluorine, chlorine and bromine. Successful correlations were obtained for most elements; the best success was for situations involving a constant number of σ bonds. The method was least successful for nitrogen, oxygen, chlorine and bromine. The modified Sanderson method performed comparably to CNDO and Jolly electronegativity calculations in most cases. Correction for molecular potential is automatically achieved using the modified Sanderson method.When the data for all elements are considered the MS model seems to work reasonably well. Correlations for B, C, Ge, F, N, As and Se seem to be as good as most methods applied to these elements. The MS method works particularly well for Si, Sn, P and S. It is inapplicable to O, Cl and Br.For compounds of elements which exist in more than one formal oxidation state, it is necessary to obtain a separate plot of E_B, versus q_i for each oxidation state. Once this is done, the calculated and experimental binding energies show good correlation. The slopes and intercepts given in Table 3 may be used for this purpose.The reason for separate correlation lines in the case of multiple oxidation states may be understood when one considers the method by which Sanderson originally calculated his atomic E values. Sanderson's original E values were calculated as the ratio of the electron density of an element stripped of all its valence electrons to the electron density of the corresponding inert gas. By considering only the inert shell configuration, Sanderson's E values are valid for filled electron shell oxidation states. However, no allowance for lone electron pairs is made. Thus, charges calculated by Sanderson's method for elements bound in less than their maximum oxidation state may not be correct relative to other oxidation states of the same element. Attempts to correct for this neglect of lone pairs were made during the course of this work by assigning E values for an electron pair or by calculating E values for non-inert shell valence configurations met with failure.The low slopes of the binding energy-charge correlations for oxygen and the halogens may also be explained by the method Sanderson used to calculate his atomic E values. Sanderson assumed that all elements shared all valence electrons in bonding. This is not the case for the halogens or oxygen which retain essentially inert lone electron pairs. Since the effect of these lone pairs is not specifically dealt with, the charges calculated by Sanderson's method and the MS method are larger than they should be in the case of elements which retain nonbonded lone pairs.Throughout these studies, it has been noted that the MS method needs no correction for molecular potential. This may be explained by the manner in which group E values are calculated. Since the electronegativities of the atoms comprising a group are “sequentially” equalized from the terminal atom of a group inward to the site of the central atom, through bond inductive effects are accounted for. This procedure reduces a multiatom group to a form in which it may be treated as a single atom attached to the atom of interest. In this form, a molecule is reduced to Pauling's “nearest neighbor” picture. Thomas¹⁹ has found that Pauling's “nearest neighbor” approximation works well for correlating ESCA data of small (e.g. methane-line) molecules without additional correction for molecular potential. Thus, the MS method has reduced a molecule to a form where the “nearest neighbor” approximation is applicable.The MS method works well for covalent molecules. As was pointed out earlier, the method fails for ionic solids primarily because of anomalies introduced by the Madelung potential. It is speculated that the MS method will work well for isolated ionic molecules in the gas-phase.     

Metall-π-komplexe von benzolderivaten : III. Bis(diphenylphosphino-h6-benzol)-chrom(0)

Rhodium complexes containing poly(pyrazolyl)borate ligands are described, and the fluxional nature of some of them considered.     

Resolution enhancement of a.c. polarographic peaks by deconvolution using the fast fourier transform

A method for resolution enhancement of a.c. polarograms (voltammograms) is presented. The method is based on deconvolution using fast Fourier transforms. Overlapped a.c. polarograms are mathematically narrowed and sharpened, retaining the peak position and linear proportionality of the sharpened peak height with concentration. The advantages and limitations of the method are demonstrated on simulated and experimental a.c. polarograms. The same approach is applicable to related techniques such as. differential pulse and square-wave polarography.     

Sulfur heterocycles. I. Use of 4,4-dimethyl-1,3-oxathiolane-3,3-dioxide as a carbonyl anion equivalent

The title heterocycle is used as a carbonyl anion equivalent in the preparation of aldehydes and α-silyl ketones; the key step is the thermal demasking of the heterocycle by loss of isobutylene and sulfur dioxide.