Abstract
A new Schiff-base macrocycle is obtained by the lead(
ii
) ion templated [2+2] condensation of 3,5-diacetyl-1
H
-1,2,4-triazole and 1,4-diaminobutane in the presence of sodium hydroxide. Transmetallation of the resulting dilead complex, Pb
2
(L2)(ClO
4
)
2
1
, in acetonitrile with two equivalents of CoCl
2
·6H
2
O leads to the isolation of an orange, six-coordinate complex, [Co
II
2
(L2)(OH
2
)
3
(NCCH
3
)](ClO
4
)
2
·H
2
O·2CH
3
CN
2
. Subsequent reaction of
2
with two equivalents of NaOCN or NEt
4
Cl yielded red-purple five-coordinate [Co
II
2
(L2)(NCO)
2
]
3
and red five-coordinate [Co
II
2
(L2)(Cl)
2
]·1.5CH
3
CN
4
, respectively. In all three air-stable dicobalt complexes the macrocycles contain two high-spin cobalt(
ii
) centers which are weakly antiferromagnetically coupled (2
J
= −3.0, −0.4, −3.5 cm
−1
for
2
,
3
and
4
, respectively). Complexes
2-4
have been characterized by X-ray diffraction and are the first structurally characterised complexes of a triazolate-containing macrocycle to date.
Three different complexes of L2
2−
are isolated by varying the anions present: all are high-spin triazolate-bridged dicobalt(
ii
) macrocyclic complexes but in one complex the cobalt(
ii
) ions are six-coordinate whilst in the other two complexes they are five-coordinate.