Answer to Question #116455 in Inorganic Chemistry for Sonali Mallick

Question

Which transition metal ion compounds have their observed magnetic moment values that agree very well with the spin only values and why

Answer 1

The magnetic moments of compounds of first half of transition series are fairly close to their calculated spin only magnetic moments and are quite different from calculated magnetic moments based upon spin and orbital contributions. However, in the later half of the compounds of first transition series, the observed values are slightly higher than the calculated spin only values. This means that in the first transition series, orbital contribution to the magnetic magnetic moments is negligible. Two information can be useful in establishing details of electronic structure and stereochemistry. We discuss below the important features of some complexes of first transition scries with different dⁿ configurations

d¹ system

Titanium (III) octahedral complexes having t_2g¹ configuration such as [Ti(II20)6]³⁺ are coloured and paramagnetic. These have magnetic moment of 1.8 B.M. at room temperature. This value ishigher than the expected spin only value of 1.73 B.M. and is attributed to the partially quenched orbital contribution.