Cyanide-bridged bimetallic assemblies
[Ni(pn)2]2[Fe(CN)6]X·catnH2O
(X = ClO4
- and n = 2
(1); X =
BF4
- and n = 2 (2); X
= PF6
- and n = 2
(3)) and
[Ni(1,1-dmen)2]2[Fe(CN)6]X·nH2O
(X = ClO4
- and n = 2
(4);
X = BF4
- and n = 3
(5); X = PF6
- and n
= 2 (6); X =
CF3SO3
- and n =
2 (7); X = BzO- and n = 6
(8); X =
I- and n = 4 (9); X =
N3
- and n = 4 (10); X
= NCS- and n = 1 (11); X =
NO3
- and n = 4 (12))
have been
prepared (pn = 1,2-propanediamine, 1,1-dmen =
1,1-dimethylethylenediamine). 7 crystallizes in a
monoclinic space
group P21/m (no. 11), with
a = 10.300(6), b = 20.632(4),
c = 10.352(7) Å, β = 109.45(4)°,
V = 2074(1) Å3 for
Z = 4. 8 crystallizes in a triclinic space group
P1̄ (no. 2), a = 10.413(6),
b = 22.060(6), c = 10.377(3) Å,
α =
101.78(2), β = 95.71(4), γ = 77.29(3)°,
V = 2272(1) Å3 for Z = 2.
10 crystallizes in triclinic space group
P1̄ (no.
2), a = 10.314(1), b =
10.374(1), c = 10.233(1) Å, α =
93.23(1), β = 106.15(1), γ = 86.37(1)°,
V = 1045.0(2) Å3
for Z = 2. In each compounds
[Fe(CN)6]3- coordinates to
four [Ni(1,1-dmen)2]2+ cations through
four cyano nitrogens
on a plane, providing a 2-D sheet of a square structure extended by
Fe-CN-Ni linkages. The square with four
Fe(III) ions at the corners and four trans Ni(II)
on the edges shows a slight distortion to a rhombus. A
ferromagnetic
interaction operates within the sheet in all the compounds. The
overall magnetic property is governed by the intersheet
separation: a small intersheet separation provides metamagnets
(1, 2, 3, 4, 6,
11) owing to intersheet antiferromagnetic
interaction, whereas a large intersheet separation (>10 Å) provides
ferromagnets (5, 7, 8, 9,
10, 12). The ferromagnets
became metamagnets on dehydration owing to shortening of the intersheet
separation.
