Water-free rare earth(III) hexacyanoferrate(III) complexes, {Ln(DMF) ₆(µ-CN)₂Fe(CN)₄}_∞ (DMF = N,N-dimethylformamide; Ln = rare earths excluding Pm), were synthesized in dry DMF through the metathesis reactions of [(18-crown-6)K] ₃Fe(CN)₆ with LnX₃(DMF)_n (X = Cl or NO₃). Anhydrous DMF solutions of LnX₃(DMF) _n were prepared at room temperature from LnCl₃ or LnX₃·nH₂O under a dynamic vacuum. Compounds were characterized by IR, X-ray powder diffraction, elemental analysis, and single crystal X-ray diffraction. Infrared spectra reveal that a monotonic, linear relationship exists between the ionic radius of the Ln and the ν _μ-CN stretching frequency. X-ray powder diffraction data are in agreement with powder patterns calculated from single crystal X-ray diffraction results indicating that each compound consists of one pure crystalline phase. This agreement is a useful alternative for bulk sample confirmation when elemental analyses are difficult to obtain. Eight-coordinate Ln(III) metal centers are observed for all structures. Trans-cyanide units of [Fe(CN) ₆]³⁻ form isocyanide linkages with Ln(III) resulting in one-dimensional polymeric chains.

Rare earth(III) tetracyanometalate(II) complexes [Ln(DMF) _n]₂[M(CN)₄]₃ (M = Ni, Pd, Pt) have been synthesized and structurally characterized. The assumption that only the size (identity) of rare earth element dictates the observed structure type has been proven false. The coordination number of the rare earth metal (n = 5 or 6) was found to depend on the identity of the group-10 metals as well as the identity of the rare earth metal.

Complexes [LnX(DMF)_n][M(CN)₄] (where X = Cl⁻ or NO₃⁻ ) with a Ln:M ratio of 1:1 have been synthesized and structurally characterized. The anion [Pt(CN)₄]²⁻ was not able to replace the nitrate ligand of [Ce(NO₃)(DMF)₅][Pt(CN) ₄]; however, the anion [Pt(CN)₄]²⁻ was able to replace the chloride ligand to produce [Ce(DMF)₅] ₂[Pt(CN)₄]₃.