Crystal Structures and Properties of MMX-Chain Compounds Based on Dithiocarboxylato-Bridged Dinuclear Complexes - Material Designs and New Physical Properties in MX-and MMX-Chain Compounds - page 176

Fig. 9.26 Temperature dependence of the magnetic susceptibility of [Pt 2 (MeCS 2 ) 4 I] 1 (1)[ 31 ]

and nearest-neighbor interdimer Coulomb repulsion ( V ). Since only the charge
degree of freedom is lost while the spin degree of freedom is maintained below
T M-S , Kitagawa et al. have concluded that the semiconducting state can be

considered to be a 4 k F CDW, that is a Mott Hubbard insulator in a half-filled

band with magnetic disorder and often lead to a SDW or spin-Peierls ground state
at low temperatures [ 31 ]. Such the Mott Hubbard transition usually shows no

w M since it is a crossover-type transition from the itinerant-
electron (Pauli) paramagnetism to localized-electron paramagnetism.

obvious anomaly in

9.2.7.2 [Pt 2 (EtCS 2 ) 4 I] 1 (2)

The temperature dependence of the magnetic susceptibility of [Pt 2 (EtCS 2 ) 4 I] 1 (2)
is shown in Fig. 9.27 [ 32 ]. The magnetic susceptibility in the metallic state above
T M-S ¼ 10 5 emu mol 1 . The low susceptibility is

consistent with Pauli paramagnetism as one may expect for a conductor. Since this
compound shows no obvious anomaly in

205 K is of the order of ca. 1

w M with the metal-semiconductor transi-

tion, the Mott Hubbard transition (4 k F -CDW) is considered to be a plausible

origin of the metal-semiconductor transition, similar to compound 1.However,the
solid-state properties of 2 cannot be perfectly understood by a simple 1D band model.