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

Abstract

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 italicz 2‐type orbital. Complexes 1–4 can be viewed as new metalloligands for metal assemblies.

{CoIIIMnIII}ncorrugated chains based on heteroleptic cyanido metalloligands

“…The coordination environment of the metal ion in this case is again distorted octahedral, the distortion being mainly due to the reduced bite angle of the chelating ligand [81.6(1) (1) or 82.5(1) (2)]. The values are very close to the corresponding one in the structure of the complex [Co(phen)(CN) 4 ] À [82.9(1) ], 22 which considerably resembles the {Co(dmphen)(CN) 4 } and {Co(dmbipy)(CN) 4 } moieties in 2 and 1, respectively. The Co-C cyanido bond lengths have values in the range 1.867(3)-1.928(3) Å for 1 and 1.900(3)-1.935(3) Å for 2, with the longest bond, in each case, involving the bridging cyanide carbon (C2).…”

“…ethylenediamine and ampy ¼ 2aminomethylpyridine] together with that of the paramagnetic cobalt(II) compound PPh 4 [Co II (dmphen)(CN) 3 ] were the subject of a recent report. 22 The latter species is used here for the synthesis of 2, whereas a new member of this cobalt(III) series with the formula PPh 4 [Co III (4,4 0 -dmbipy)(CN) 4 ] whose preparation is described herein, is employed as a metalloligand to obtain compound 1.…”

Heterotrimetallic Coordination Polymers: {CuIILnIIIFeIII} Chains and {NiIILnIIIFeIII} Layers: Synthesis, Crystal Structures, and Magnetic Properties

“…Thereby, a magnetic coupling between two adjacent low‐spin [Fe(phen)(CN) 4 ] − units (model A) could be expected in the context of the spin polarization mechanism, which was proposed by McConnell 28. In this respect, it deserves to be noted that weak ferro‐ and antiferromagnetic interactions across π–π stacking have been observed in other magneto‐structurally investigated compounds 8b. 29–32…”

Heterometallic supramolecular architectures constructed from cyanido-based [CoIII(AA)(CN)4]- building-blocks (AA = 1,10-phenantroline and 2,2’-bipyridine)

“…The Co1-C cyanide and Co1-N phen bond distances cover the ranges 1.862(4)-1.904(4) and 1.965(3)-1.981(3) Å, respectively and their values are as expected. [9][10][11][12] The bis-monodentate cyanide group and the phen ligand are in-plane. All the cyanide ligands are quite linearly coordinated to the metal ion, with Co-C-N angles spanning the range 176.1(3)-178.3(4)°.…”