A series of μ-tto- (tto =
C2S4
2- =
tetrathiooxalato) bridged bimetallic Ni(II) complexes with the
general formula
(Y)2{tto[Ni(L)]2} (where Y
= Bu4N+, L = dsit =
C3Se2S3
2-
= 2-thioxo-1,3-dithiole-4,5-diselenolato (2)
and
dmise =
C3SeS4
2- =
2-selenoxo-1,3-dithiole-4,5-dithiolato (3); and where Y =
Me4N+ (4) and
Et4N+ (5), L =
dmit = C3S5
2- =
2-thioxo-1,3-dithiole-4,5-dithiolato) have been synthesized. The
single-crystal X-ray structures
of 2, 3, 4 and 5 have been
determined: 2,
(Bu4N)2{tto[Ni(dsit)]2},
monoclinic, space group P21/c,
a = 9.8893(1)
Å, b = 15.3544(1) Å, c =
17.8825(2) Å, β = 90.561(1)°, Z = 2;
3,
(Bu4N)2{tto[Ni(dmise)]2},
orthorhombic,
space group P212121,
a = 9.8286(2) Å, b = 16.1741(3)
Å, c = 34.3022(1) Å, Z = 4;
4,
(Me4N)2{tto[Ni(dmit)]2},
monoclinic, space group C2/m, a =
13.8043(4) Å, b = 10.1081(1) Å, c
= 12.0483(3) Å, β = 115.239(1)°, Z
=
2; 5,
(Et4N)2{tto[Ni(dmit)]2},
monoclinic, space group P21/n,
a = 11.8313(1) Å, b = 11.0172(2)
Å, c = 15.3014(1) Å, β = 110.951(1)°, Z = 2. All of the
complexes presented are extensively conjugated and
chalcogen-rich
with
(Bu4N)2{tto[Ni(dsit)]2}
(2),
(Bu4N)2{tto[Ni(dmise)]2}
(3), and
(Me4N)2{tto[Ni(dmit)]2}
(4) also being planar
as precursors to electrically conducting materials. The angle of
the tto−Ni−L portion of the complexes varies
with the choice of ligand and with the counterion. Cyclic
voltammetry results of 2 and 3 each show a
first
low-potential reversible redox couple followed by a second
nonreversible redox couple. The structural and
electronic properties of 2−5 are compared to
those of the recently communicated analogous complex,
(Bu4N)2{tto[Ni(dmit)]2} (1).
Electrocrystallization, interdiffusion, and chemical oxidation
experiments with 1 have yielded
black insoluble materials with high pressed powder conductivities of up
to 0.5 S/cm.
