SPIN FRUSTRATION IN THE BUTTERFLY-LIKE TETRAMERIC [NI-4(MU-CO3)(2)(AETPY)(8)][CLO4](4) [AETPY = (2-AMINOETHYL)PYRIDINE] COMPLEX - STRUCTUREAND MAGNETIC-PROPERTIES

A new tetranuclear nickel compound, showing mu-CO3 bridges and butterf ly topology has been synthesised and structurally characterised. The c omplex [Ni-4(mu-CO3)(2)(aetpy)(8)][ClO4](4), where aetpy corresponds t o (2-aminoethyl)pyridine, crystallises in the tetragonal system, space group P4(2)2(1)2 (no. 94), a = 14.523(4), c = 16.566(5) Angstrom and Z = 8. Magnetic measurements show an overall antiferromagnetic behavio ur with a quasi-degenerate set of spin levels S = 0, S = 1 and S = 2 a s a ground state, which may be rationalised in terms of a spin frustra tion system.