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
Titanium (III) octahedral complexes having t2g1 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.