Pd(III) Mott–Hubbard Compounds - Material Designs and New Physical Properties in MX-and MMX-Chain Compounds - page 42

Fig. 4.6 The nearest neighbor Pd Pd distance as a function of alkyl chain length

Fig. 4.7 Raman spectra of a series of [Pd(en) 2 Br](C 5 -Y) 2 H 2 O(4 n 12) at room temperature

compounds with longer alkyl chains ( n 9). As mentioned above, this stretching

mode is allowed in the CDW state but forbidden in the MH state. Therefore, the
compounds with short ( n 8) and long ( n 9) alkyl chains have CDW and MH

states, respectively, at room temperature.
We measured the temperature dependence of the Raman spectra and determined
the T c for the series of Pd-Br compounds. Figure 4.8 shows the phase diagram of
these compounds. With an increase in the alkyl chain length, T c steadily increased.

4.3 Stabilization of the Pd(III) MH State in Ni-Pd Mixed Metal
Complexes, [Ni 1 x Pd x (chxn) 2 Br]Br 2

We have tried another approach to decrease metal-metal distance, that is, partial
substitution with smaller Ni ions, [Ni 1 x Pd x (chxn) 2 Br]Br 2 . These complexes were
firstly synthesized by Yamashita et al. in 1997, [ 6 , 7 ] and their electronic states have