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 157

Fig. 9.6 1D chain structures of [Pt 2 (RCS 2 ) 4 I] 1 (R ¼ n -Pr (3), n -Bu (4), n -Pen (5)) in the HT

phase with an atomic numbering scheme and relevant interatomic distances (thermal ellipsoid set
at the 50 % probability level) [ 34 , 35 ]. Crystallographic mirror planes perpendicular to the 1D
chain exist at z ¼ 0, 0.5, 1

Fig. 9.7 Comparison of crystal structures of [Pt 2 (RCS 2 ) 4 I] 1 (R ¼ n -Pr (3), n -Bu (4), n -Pen (5))

viewed along the c axis (1D chain direction) [ 35 ]

The molecule colored in black is disordered in two PtS 4 planes, whereas the two
PtS 4 planes colored in gray are ordered. Twist angle between two kinds of adjacent
Pt 2 (CS 2 ) 4 units in each [Pt 2 (RCS 2 ) 4 I] 1 increases in order of R ¼ n -Pr (3)(10 )[ 34 ],

¼ n -Pen (5) (26 )[ 35 ], and the differences in
the ligand conformation between two kinds of the diplatinum units increase in the
same order. Therefore, it is considered that 5 retains threefold periodic structure in
the HT phase, since the twisting angle and the difference in the ligand conformation
between two kinds of the diplatinum units are too large to take the onefold
periodicity of a -Pt-Pt-I- period.

¼ n -Bu (4) (14 )[ 33 ], and R

R

LT Phase of [Pt 2 ( n -BuCS 2 ) 4 I] 1 (4)

The compound 4 undergoes a first-order phase transition at 213.5 K [ 51 ], where the
space group changes from I 4/ m in the RT phase to P 4/ n in the LT phase [ 33 ]. The
1D chain structure of 4 in the LT phase at 167 K is shown in Fig. 9.8 . The opposite