Molecule-based magnets constructed from hexacyanometalates

We have prepared a series of Prussian blue ferrimagnets by adding various paramagnetic, first-row transition metal cations to the following anions: CrIII(CN)₆3−, CrII(CN) ₆4−, VII(CN)₆ 4−, and Cr(CN)₅NO3−. One of these magnets, KVII[CrIII(CN)₆]-·2H ₂O·0.1KOTf orders magnetically at 376 K, which is the highest magnetic ordering temperature yet seen for a molecule-based magnet. Some of the CrII derivatives exhibit compensation behavior, and several of the compounds are susceptible to linkage isomerism. Infrared spectra, X-ray powder diffractograms, scanning electron micrographs, and variable temperature susceptibility and magnetization studies are described.; Improved preparations are given for several first-row transition metal trifluoromethanesulfonate (OTf) and p-toluenesulfonate (OTs) salts: M(OTf)_x, where M = VII, VIII, CrII, MnII, CoII, NiII , and Cs, and [M(OH₂)_n][OTs]_x, where M = TiIII, VIII, VIVO, Cr II, CrIII, MnII, FeII, CoII, NiII, and Cs. Also described are preparations of the cyanide building blocks K₄[V(CN)₆]·xH ₂O, [NEt₄]₄[V(CN)₆], K₃[Cr(CN) ₆]·xH₂O, [NEt₄]₃[Cr(CN) ₆]·xH₂O, [NEt₄]₃[Ti(CN) ₆]·2.5H₂O, [PPN]₃[Cr(CN)₆], [PPN]₃[Fe(CN)₆], [NEt₄]₃[Co(CN) ₆]·H₂O, [PPN]₃[Cr(CN)₅NO], [NEt ₄]CN, and [PPN]CN.