Change of spin-state

Electron transfer will occur more easily if the metal ion is in the low-spin configuration, as the electron density will then lie in orbitals directed towards the ligand. Changes of spin state during reaction should be avoided, while reactions should be complementary if possible. 

The change of spin state of Co3+ ions with changing temperature or pressure is an intriguing feature of cobalt-based perovskite compounds represented mainly by LaCo03. Due to the closeness of the crystal field... 

Since is a powerftil radiofi equency field, it causes saturation of nucleus A, i.e. ftie change of spin state of nucleus A is very rapid. Under these conditions, nucleus X does not exhibit signals corresponding to interaction wifti the two spin states of A but only a single time-averaged line is observed and this resonance signal therefore represents the true chemical shift of nucleus X. 

The recoil technique is capable of yielding angular distributions with velocity-selected targets. In addition it is particularly useful in studying the change of spin states in a scattering process, since it is easier to analyse the spin states of scattered atoms than those of electrons. Such measurements are not discussed here but the reader is referred to the articles by Bederson (1968) and Bederson and Kieffer (1971). 

In the HS state (300 K, ambient pressure) both complexes exhibit a strong distortion of the [FeN ] octahedron. The change of spin state induces noticeable shortening of the Fe-N bonds, which results in close values of the average Fe-L bond distance variations Ai = 0.170 A and 0.164 A for [Fe(phen)2(NCS)2] and [Fe(btz)2(NCS)2], respectively. Important N-Fe-N bond angles variations are also... 

The fundamental requirement for longitudinal relaxation of a spin- /a nucleus is a time-dependent magnetic field fluctuating at the Larmor frequency of the nuclear spin. Only through this can a change of spin state be induced or, in other words, can relaxation occur. Local magnetic fields arise from a... 

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