Structural distortion and magnetic behavior in cyanide-bridged Fe2IIINi2II complexes

The X-ray structure, spectroscopic, and magnetic properties of acyanide-bridged complex,([(Tp*)Fe-III(CN)(3)](2)[Ni-II(bipy)(2)](2)[OTf](2)}(.)2H(2)O (2) are described [Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate; bipy = 2,2'-bipyridine; OTf = trifluromethanesulfonate]. Magnetic measurements indicate that 2 exhibits an S = 3 ground state and slow relaxation of the magnetization. Magnetostructural comparisons to the more symmetrical analog 1[(Tp*)Fe-III(CN)(3)](2)[Ni-II(DMF)(4)](2)-[OTf](2)}(.)2DMF (1) are also described. Surprisingly, the magnetic properties of 1 and 2 are similar despite the presence of a non-planar ((Fe2Ni2II)-Ni-III(mu-CN)(4)} core and severely distorted NiII coordination sphere in 2, suggesting that the Ni'l centers play a minor role in the slow magnetization relaxation behavior of the clusters. (c) Wiley-VCH Verlag GmbH & Co. KGaA.