Novel tetrahedral cobalt(ii) silanethiolates: structures and magnetism.

Three heteroleptic complexes of Co(ii) tri--butoxysilanethiolates have been synthesized with piperidine [Co{SSi(OBu)}(ppd)] 1, piperazine Co{SSi(OBu)}(NH)·2CHCN 2, and -ethylimidazole [Co{SSi(OBu)}(etim)] 3. The complexes have been characterized by a single-crystal X-ray, revealing their tetrahedral geometry on Co(ii) coordinated by two nitrogen and two sulfur atoms. Complexes 1 and 3 are mononuclear, whereas 2 is binuclear. The spectral properties and thermal properties of 1-3 complexes were established by FTIR spectroscopy for solid samples and TGA. The magnetic properties of complexes 1, 2, and 3 have been investigated by static magnetic measurements and X-band EPR spectroscopy. These studies have shown that 1 and 3, regardless of the similarity in structure of CoNS cores, demonstrate different types of local magnetic anisotropy. Magnetic investigations of 2 reveal the presence of weak antiferromagnetic intra-molecular Co(ii)-Co(ii) interactions that are strongly influenced by the local magnetic anisotropy of individual Co(ii) ions.