Supramolecular aspects of iron(II) crown-dipyridyl spin-crossover compounds

The synthesis, structures and magnetism of the complexes [Fe-II(3-bpp)(2)][bpmdcK](SeCN)(1.7) (ClO4)(1.3)MeOH center dot H2O (1), I Fe-II(3-bpp)(2)](4)[bpmdcH(2)(H2O)(2)](ClO4)(10)center dot 7H(2)O center dot 3McOH (2) and cis-[Fe-2(II)(NCSe)(2) ((3.5-Me-2 pz)(3)CH)(2)(mu-bPmdc)].2MeCN (3) (where 3-bpp=2.6-di(pyrazole-3yl)pyridine, bpmdc =N,N'-bis(4-pyridyl-methyl)diaza-18-crown-6) and (3,5-Me2pz)(3)CH = tris(3,5-dimethylpyrazole)methane, are presented. These compounds form a study of the supramolecular influence of host-guest/crown-ether interactions and cation-to-crown hydrogen-bonding effects upon d(6) spin transitions, the latter occurring above, or near to, room temperature in 1 and 2. Desolvation effects also influence the T-1/2 values. The dinuclear compound 3 contains covalent pyridyl (crown) N to Fe bridge bonding and remains high spin. (C) 2011 Elsevier B.V. All rights reserved.