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RESEARCH PRODUCT

Cyanido‐Bearing Cobalt(II/III) Metalloligands – Synthesis, Crystal Structure, and Magnetic Properties

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New examples of cyanido-bearing cobalt(III/II) complexes have been obtained by treatment of CoCl2·6H2O with bidentate nitrogen donors and potassium cyanide in a methanol/water mixture. Depending on the chelating ligand, the cobalt(III) complexes PPh4[Co(en)(CN)4] (1, en = ethylenediamine), PPh4[Co(ampy)(CN)4]·1.5H2O [2, ampy = 2-(aminomethyl)pyridine], and PPh4[Co(phen)(CN)4]·CH3OH·0.25H2O (3, phen = 1,10-phenanthroline) and the cobalt(II) complex PPh4[Co(dmphen)(CN)3]·3H2O (4, dmphen = 2,9-dimethyl-1,10-phenanthroline) were obtained. The complexes were characterized by single-crystal X-ray diffraction and variable-temperature magnetic measurements. They are all mononuclear species with six-coordinate cobalt(III) (1–3) and five-coordinate cobalt(II) centers (4), and two nitrogen atoms from each bidentate ligand (1–4) and four (1–3) or three cyanide carbon atoms (4) build somewhat distorted octahedral (1–3) or square-pyramidal (4) surroundings. Complexes 1–3 are diamagnetic cobalt(III) compounds, whereas 4 is a low-spin cobalt(II) complex that exhibits Curie behavior in the temperature range 10–300 K. The g values of the X-band electron paramagnetic resonance (EPR) spectrum of 4 both in the solid state and in dichloromethane solution at 4.0 K (g⟂ = 2.28 > g∥ = 2.0) reveal that its unpaired electron is defined by a d-type orbital. Complexes 1–4 can be viewed as new metalloligands for metal assemblies.