LIGAND FIELD THEORY FOR PENTACOORDINATE MOLECULES .2. A CRYSTAL FIELD-SPIN-ORBIT COUPLING TREATMENT OF D1 D3 D6 AND D8 CONFIGURATIONS IN TRIGONAL-BIPYRAMIDAL MOLECULES AND MAGNETIC PROPERTIES OF E-GROUND TERMS

The energy levels for a d1ion under the combined action of spin-orbit coupling and a crystal field oftrigonal-bipyramidal symmetry have been deduced and the form of the temperature variation of the magnetic moment for the 2E″ ground state, using both the zero-order and first-order corrected wave functions,is given. In addition, the magnetic properties anticipated for the 4E′ (d3), 6E″ (d6), and 3E′ (d8) ground states have been evaluated. It is shown that the magnetic properties of the two compounds TiBr3.2N(CH3)3 and TiBr3.2N(CH3)3 cannot be explained on the basis of a D3h ligand field and thatasmall additional low-symmetry ligand field component (in the xy plane) must be present. The magnetic properties anticipated for C2v symmetry have also been evaluated and it appears that the splittingof the 2E″ statein these molecules is of the order of 300 cm-1. A similar situation also occurs in CrCl3′.2N(CH3)3 although, here, the deviation from that predicted for the 4E′ state is much larger and a low-symmetry component of at least 2000 cm-1 must be invoked to explain the observed temperature-independent, spin-only moment. The magnetic properties of some recently reported species of C3v symmetry are discussed in the light of the predicted behavior for the d6 and d8configurations. © 1969, American Chemical Society. All rights reserved.