Magnetic properties strong-field ligands

States lower than Mn11 are usually stabilized by strong field ligands giving rise to spin-paired systems whereas the magnetic properties of Mnv, MnVI and Mnvu have not been widely studied. 

J.H. Weber and D.H. Busch (1965). Complexes derived from strong field ligands - XIX. Magnetic properties of transition metal derivatives of 4,4, 4",4" -tetrasulfophthalocya-nines. Inorg. chem, 4, 469-471. 

THE MAGNETIC PROPERTIES OF COMPLEXES WEAK- AND STRONG-FIELD LIGANDS... 

The formation of diimine systems by Schiff -base-type condensation of suitable aldehydes and primary amines has been widely applied. Those reported are mostly strong field systems and their relevance to the spin crossover field is generally in systems of the kind [Fe(diimine)2(NCS)2]. The effect of the incorporation of substituents likely to hinder coordination has been studied. Robinson and Busch noted a fundamental difference at room temperature in the electronic properties of the [Fe N6]2+ derivatives of 2-pyridi-nalmethylhydrazone and 2-pyridinal-dimethylhydrazone, those of the former being low spin and those of the latter high spin [49]. The temperature-dependence of the magnetism of the latter complex was not reported but may well be of interest. However, spin crossover [Fe(diimine)3]2+ systems have been characterised for systems where the incorporation of appropriate substituents has reduced the ligand field. 

It is important to mention that a reduction of ligand field symmetry can strongly alter the magnetic properties of ions If the symmetry of a 3d1 system with an Oh-symmetric ligand field is reduced (e.g., by an orthorhombic distortion), the entire orbital moment will be quenched and spin-only magnetism is observed. 

If the metal of the first transition series has a dn configuration (in its relevant oxidation state) and forms an octahedral complex, for what values of i could magnetic properties alone distinguish between strong-field and weak-field ligands ... 

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