In this paper, the authors recall and systemize the restrictions to the application of Job's method, illustrate its use associated to proton magnetic resonance spectral intensities, and present some results of a computer program they developed for the case of multiple equilibria.

The problem of a relativistic spin 1/2 particle confined to a one-dimensional box is solved in a way that resembles closely the solution of the well known quantum-mechanical textbook problem of a non-relativistic particle in a box. The energy levels and probability density are computed and compared with the non-relativistic case. Resumo. O problema de uma partícula de spin 1/2 confinada por uma caixa a uma dimensãoé resolvido de uma maneira muito semelhanteà da resolução do problema de uma partícula no-relativista numa caixa referido em muitos livros introdutórios de Mecânica Quntâica. Os níveis de energia e a densidade de probabilidade são calculados e comparados com os valores não-relativistas.

The nature and types of lone-pair effects on nuclear spin coupling constants are reviewed in the context of a localized bond description of molecular electronic structure. Emphasis is placed on the importance of residual delocalization involving the otherwise lone-pair orbital, in terms of which the effect of an X lone-pair, when compared with an isoelectronic Y-H or X-H+ group or with an X-R group, and its orientational dependence can be interpreted. One-, two-and three-bond coupling constants are considered and the importance of lone-pair effects for configurational and conformational information is stressed and illustrated. They also serve for a better understanding of substituent inductive effects on coupling constants.A large collection of illustrative examples are presented, with particular attention paid to couplings involving H, C, N, F and P nuclei, organized in a systematic manner into nine categories. The signs of the lone-pair effects on the reduced coupling constants are found to be independent of the actual nuclei under study in the same category. This is taken as an indication that the electron lone-pairs mainly affect the Fermi contact contribution to the coupling and, accordingly, an interpretation is given in terms of simple sum-over-states models. In addition, symmetry-based relationship are established involving the sign of lone-pair effects in coupling constants between nuclei which are a different number of bonds apart.KEY WORDS NMR Multinuclear spin coupling Lone-pair effects Substituent effects Stereochemistry MO Sum-over-states models Electron delocalization CONTENTS

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A semi-quantitative estimate has been made of the contributions to the proton and nitrogen chemical shifts in pyridine and the pyridinium cation. The difference between the nitrogen chemical shifts in Py and PyHf is due mainly to the large paramagnetic term arising from the n+z* transition of pyridine. The contributions to the proton chemical shifts in Py due to the magnetic anisotropy of the nitrogen atom, and the polarization of the C-H bonds by the nitrogen lone pair, have been calculated. The remaining part of the chemical shifts relative to benzene is found to be well correlated with s.c.f. calculations of the T electron densities.

A multinuclear ( 1 H, 13 C, 17 O, 51 V) 1D and 2D NMR study of the complexation of L-lactic acid with vanadium(V) and hydrogen peroxide shows that four peroxo complexes are formed in aqueous solution in the pH range 1−7. Two isomeric 2:2:1 (metal:ligand:peroxo) complexes, together with a 2:2:2 species, are found over the entire pH range. At pH [a]

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