Ligand field (d-d) transitions of Os4' and Ir4' doped into the cubic host, Cs2GeF6, have been studied at low temperatures using absorption and magnetic circular dichroism (MCD) spectroscopy. OsFt-shows many sharp, well-defined lines permitting a detailed interpretation of the interconfigurational d-d bands. (The crystal was too dilute for observation of the intraconfigurational bands.) Two intense alg progressions dominate the spectrum and have been assigned as A', (ST', (t2,4)) -T1, ('TI, (t2:e, )) and T1, (3Al, (t2;e,)). Examination of the weaker lines within these two progressions shows that transitions to T g states are generally less intense than those to T1, states. No transitions to A',, A, , or Eg states are observed. The assigned states in OsF2-are fit well by the parameters B = 625 cm-', C = 2969 cm-', Dq = 2450 cm-', and { = 2800 cm-I. For IrF6*-, intraconfigurational transitions within the spin-orbit split 2T2g (t 2: ) ground state are observed in addition to the interconfigurational transitions. The latter are not as well resolved as in OSF~~-, and a less detailed interpretation has been possible. However, four excited states are assigned which are fit well by the ligand field parameters B = 641 cm-I, C = 3140 cm-l, Dq = 2450 cm-', and p = 3500 cm-I.
