Magnetic properties of transition metal ions

Magnetic Properties of Transition Metal Ions We leam a great deal about an element s electron configuration from atomic spectra, and magnetic studies provide additional evidence. 

The magnetic properties of transition metal ions support these assignments. Recall from Section 8.3 that an unpaired electron generates a magnetic field due to its spin. Consequently, an atom or ion that contains unpaired electrons is attracted to an external magnetic field, and we say that the atom or ion is paramagnetic. For example, consider the electron configuration of silver ... 

Future applications of the AOM will include the analysis of the optical spectra and magnetic properties of transition metal ions located in polynuclear systems. Calculations on infinite structures (chains) have already been reported [110], and a parametrization scheme for the evaluation of orbital-exchange parameters in magnetically coupled dinuclear complexes was presented recently [111]. Another interesting aspect concerns the dynamic extension of the AOM which allows, for example, Jahn-Teller energies to be calculated [112, 113]. Finally, it should be... 

So far, it has been assumed that the ligands around the metal ion are in a regular octahedral arrangement. We now go on to show that this is not possible for certain configurations of the d electrons. The theory is essentially that of Jahn and Teller (68), but we shall develop it in a qualitative way rather than in the elegant form in which they first presented it. Historically, their ideas were originally applied to the interpretation of the magnetic properties of transition-metal compounds (187) the stereochemical applications are much more recent (35, 104). 

The magnetic properties of transition-metal complexes can readily be understood in terms of CFT. Transition metal ions have partially filled d orbitals. If these orbitals are degenerate, Hund s rule predicts that unpaired electrons will be present. For example, a metal ion containing three d electrons (called a cf system) should have three unpaired electrons C O ) a metal ion... 

Crystal-field theory helps us understand the magnetic properties and some important chemical properties of transition-metal ions. From Hund s rule, we expect electrons to always occupy the lowest-energy vacant orbitals first and to occupy a set of degenerate (same-energy) orbitals one at a time with their spins parallel. 000 (Section 6.8) Thus, if we have a d d, or d octahedral complex, the electrons go into the lower-energy t2 orbitals, with their spins parallel. When a fourth electron must be added, we have the two choices shown in Figure 23.31 The electron can either go into an e orbital, where... 

Many biological molecules contain iron and Mossbauer spectroscopy is a useful tool for the study of proteins and enzymes. The measurement of the magnetic properties of transition metal elements in biological molecules by MS, NMR and EPR is an important way of characterizing the electronic state of the metal ion, and hence of providing a clue to the structure and function of the molecule. Mossbauer spectroscopy may be used to study their chemical state and bonding and to obtain qualitative data on the local structure and symmetry in their neighbourhood. 

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