Περίληψη:
The exploration of the NiX2/py(2)CO/Et3N ( X= F, Cl, Br, I; py(2)CO =
di-2-pyridyl ketone; Et3N = triethylamine) reaction system led to the
tetranuclear
[Ni4Cl2py(2)C(OH)O(2)py(2)C(OMe)O(2)(MeOH)(2)]Cl-2 center dot
2Et(2)O (1 center dot 2Et(2)O) and
[Ni4Br2py(2)C(OH)O(2)py(2)C(OMe)O(2)(MeOH)(2)]Br-2 center dot
2Et(2)O (2 center dot 2Et(2)O) and the trinuclear
[Ni-3py(2)C(OMe)O(4)]I-2 center dot 2.5MeOH (3 center dot
2.6MeOH), [Ni-3py(2)C(OMe)O(4)](NO3)(0.65)I-1.35 center dot 2MeOH
(4 center dot 2MeOH) and [Ni-3py(2)C(OMe)O(4)](SiF6)(0.8)F-0.4
center dot 3.5MeOH (5 center dot 3.5MeOH) aggregates. The presence of
the intermediate size Cl- and Br- anions resulted in planar tetranuclear
complexes with a dense hexagonal packing of cations and donor atoms
(tetramolybdate topology) where the X-anions participate in the core
acting as bridging ligands. The F- and I- anions do not favour the above
arrangement resulting in triangular complexes with an isosceles
topology. The magnetic properties of 1-3 have been studied by
variable-temperature dc, variable-temperature and variable-field ac
magnetic susceptibility techniques and magnetization measurements. All
complexes are high-spin with ground states S = 4 for 1 and 2 and S = 3
for 3.
