Title:
Topological control in two-dimensional cobalt(II) coordination polymers
by pi-pi stacking interactions: Synthesis, spectroscopic
characterization, crystal structure, and magnetic properties
Abstract:
The reactions of CoX2 (X = Br, Cl) with the planar, bidentate bridging
ligand 2,1,3-benzothiadiazole (btd) in Me2CO led to the 2D coordination
polymers [CoBr2(btd)](n), (1) and [CoCl2(btd)](n), (2). The
structure of 1 was determined by single-crystal X-ray crystallography.
Complex I (C6H4Br2CoN2S, monoclinic, P2(1)/m, a = 3.742(3), b =
13.075(9), c = 9.092(6) Angstrom, beta = 90.09(2)degrees, Z = 2, theta
-2 theta, R-1 = 0.0298, wR(2) = 0.0793) consists of [Co(mu
-Br)(2)](n) linear chains running along the a axis linked via mu -btd
ligands along the b axis. The columns of stacked btd molecules present
in the crystal structure of the free ligand are maintained in the
lattice of 1. XRD data revealed that 2 is isostructural with 1. The
magnetic properties of both complexes can be explained by the presence
of a very weak ferromagnetic intrachain Co . . . Co exchange interaction
through the (mu -X)(2) bridges and a moderate antiferromagnetic Co . . .
Co interaction through the mu -btd bridges. The new complexes were also
characterized by EPR, IR, and UV/VIS spectra, and all data are discussed
in terms of the nature of bonding and known structures. (C) 2001
Academic Press.
