Synthesis,kinetics, and mechanism for adduct formation of tetraaza Schiff base cobalt(II) complexes with diorganotin(IV)dichlorides in dimethylformamide solvent

The kinetics and mechanism of the adduct formation of diorganotin(IV)dichlorides with Co(II) tetraaza Schiff base complexes, such as [Co(ampen)] {[N,N′‐ethylenebis‐(o‐amino‐α‐phenylbenzylideneiminato)cobalt(II)]}, [Co(campen)] {[N,N′‐ethylenebis‐(5‐chloro‐o‐amino‐α‐phenylbenzylideneiminato)cobalt(II)]}, and [Co(amaen)] {[N,N′‐ethylenebis‐(o‐amino‐α‐methylbenzylideneiminato)cobalt(II)]}, were studied spectrophotometrically. The kinetic parameters and the rate constant values show the following acceptor tendency trend for the diorganotin(IV)dichlorides: Ph₂SnCl₂> Me₂SnCl₂> Bu₂SnCl₂. Adducts have been separately synthesized and fully characterized by ¹¹⁹SnNMR, IR, UV–vis spectra, and elemental microanalysis (C,H,N) methods. The trend of the rate constants for the adduct formation of the cobalt complexes with a given tin acceptor decreases as follow: Co(amaen) > Co(ampen) > Co(campen). The linear plots of k_obs vs. the molar concentration of the diorganotin(IV)dichlorides, the high span of the second‐order rate constant k₂ values, and the large negative values of AS^≠ suggest an associative (A) mechanism for the acceptor–donor adduct formation. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 499–507, 2010     

Donor property of cobalt(II) Schiff base complexes toward triphenyltin(IV)‐chloride: A kinetic study

In this study, some cobalt(II)tetraaza Schiff base complexes were used as donors in coordinating to triphenyltin(IV)chloride as acceptors; the kinetics and mechanism of the adduct formation were studied spectrophotometrically. Co(II)tetraaza Schiff base complexes used were [Co(amaen)][N,N′‐ethylene‐bis‐(o‐amino‐α‐methylbenzylideneiminato)cobalt(II)] ( 1 ), [Co(appn)] [N,N′‐1,2‐propylene‐bis‐(o‐amino‐α‐phenylbenzylideneiminato)cobalt(II)] ( 2 ), [Co(ampen)] [N,N′‐ethylene‐bis‐(o‐amino‐α‐phenylbenzylideneiminato)cobalt‐(II)] ( 3 ), [Co(cappn)][N,N′‐1,2‐proylene‐bis‐(5‐chloro‐o‐amino‐α‐phenylbenzylideneiminato)cobalt(II)] ( 4 ), and [Co(campen)] [N,N′‐ethylene‐bis‐(5‐chloro‐o‐amino‐α‐phenylbenzylid‐eneiminato)cobalt(II)] ( 5 ). The reactivity trend of the complexes in interaction with triphenyltin(IV)chloride was Co(amaen) > Co(appn) > Co(ampen) > Co(cappn) > Co(campen). The linear plots of k_obs versus the molar concentration of the triphenyltin(IV)chloride, a high span of the second‐order rate constant k₂ values, and large negative values of ΔS^≠ and low ΔH^≠ values suggest an associative (A) mechanism for the acceptor–donor adduct formation. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 635–640, 2012     

Crystal structures and Hirshfeld surface analysis of transition‐metal complexes of 1,3‐azolecarboxylic acids

The crystal structures of five new transition‐metal complexes synthesized using thiazole‐2‐carboxylic acid (2‐Htza), imidazole‐2‐carboxylic acid (2‐H₂ima) or 1,3‐oxazole‐4‐carboxylic acid (4‐Hoxa), namely diaquabis(thiazole‐2‐carboxylato‐κ²N,O)cobalt(II), [Co(C₄H₂NO₂S)₂(H₂O)₂], 1 , diaquabis(thiazole‐2‐carboxylato‐κ²N,O)nickel(II), [Ni(C₄H₂NO₂S)₂(H₂O)₂], 2 , diaquabis(thiazole‐2‐carboxylato‐κ²N,O)cadmium(II), [Cd(C₄H₂NO₂S)₂(H₂O)₂], 3 , diaquabis(1H‐imidazole‐2‐carboxylato‐κ²N³,O)cobalt(II), [Co(C₄H₂N₂O₂)₂(H₂O)₂], 4 , and diaquabis(1,3‐oxazole‐4‐carboxylato‐κ²N,O⁴)cobalt(II), [Co(C₄H₂NO₃)₂(H₂O)₂], 5 , are reported. The influence of the nature of the heteroatom and the position of the carboxyl group in relation to the heteroatom on the self‐assembly process are discussed based upon Hirshfeld surface analysis and used to explain the observed differences in the single‐crystal structures and the supramolecular frameworks and topologies of complexes 1 – 5 .     

Synthesis,crystal structures and characterizations of two homochiral coordination polymers based on a chiral reduced Schiff base ligand

Two homochiral coordination polymers based on a chiral reduced Schiff base ligand, namely poly[(μ₅‐4‐{[(NR,1S)‐(1‐carboxylato‐2‐phenylethyl)amino]methyl}benzoato)zinc(II)], [Zn(C₁₇H₁₅NO₄)]_n, (1), and poly[(μ₅‐4‐{[(NR,1S)‐(1‐carboxylato‐2‐phenylethyl)amino]methyl}benzoato)cobalt(II)], [Co(C₁₇H₁₅NO₄)]_n, (2), have been obtained by hydrothermal methods and studied by single‐crystal X‐ray diffraction, elemental analyses, powder X‐ray diffraction, thermogravimetric analysis, IR spectroscopy and fluorescence spectroscopy. Compounds (1) and (2) are isostructural and crystallize in the P2₁2₁2₁ space group. Both display a three‐dimensional network structure with a one‐dimensional channel, with the benzyl group of the ligand directed towards the channel. An investigation of photoluminescence properties shows that compound (1) displays a strong emission in the purple region.     

A one‐dimensional zigzag coordination polymer of di­aqua­(pyridine‐2,3‐di­carboxyl­ato)­cobalt(II)

The asymmetric unit of the title one‐dimensional coordination polymer, catena‐poly­[[μ‐pyridine‐2,3‐di­carb­oxyl­ato‐1κO:2κ²N,O′‐bis­[di­aqua­cobalt(II)]]‐μ‐pyridine‐2,3‐di­carboxyl­ato‐1κ²N,O:2κO′:1′κO′], [Co(C₇H₃NO₄)(H₂O)₂]_n, is composed of a cobalt(II) ion, a pyridine‐2,3‐di­carboxyl­ate dianion and two water mol­ecules. The polymer has a zigzag structure consisting of a chain of edge‐fused rings, and the polymer chains are linked by O—H⃛O hydrogen bonds into a three‐dimensional framework.     

A heterotrimetallic Cu–Co–Zn complex with the 2,2′‐iminodiethanol ligand

The crystal structure of the title compound, triacetato‐1κO;3κ⁴O,O′‐(2,2′‐imino­diethanol)‐1κ³O,N,O′‐bis­(μ‐2,2′‐iminodi­ethanol­ato)‐1κ²O:2κ⁶O,N,O′:3κ²O′‐cobalt(III)copper(II)zinc(II), [CoCuZn(C₄H₉NO₂)₂(C₂H₃O₂)₃(C₄H₁₁NO₂)], shows a mol­ecule with a triangular three‐metal core. The metal sites were refined with full occupancies, but the possibility that the Zn and Cu positions are actually mixed Cu/Zn sites cannot be excluded. The inter­metallic Cu⋯Co and Co⋯Zn distances are 2.924 (3) and 2.906 (3) Å, respectively. The neutral mol­ecules are held together by N—H⋯O hydrogen bonds involving amine groups from the 2,2′‐iminodiethanol ligands and acetate groups to build two‐dimensional layers.     

Two cobalt(III) mono‐dimethylglyoximates isolated from one reaction

The reaction of cobalt(II) nitrate hexahydrate with dimethylglyoxime (DMGH₂) and 1,10‐phenanthroline (phen) in a 1:1:2 molar ratio results in two Co^III mono‐dimethylglyoximates having two chelating phen ligands in cis positions and the Co^III atom coordinated by six N atoms in a distorted octahedral coordination geometry. The isolated products differ in the deprotonation state of the DMGH₂ ligand. In [μ‐hydrogen bis(N,N′‐dioxidobutane‐2,3‐diimine)]tetrakis(1,10‐phenanthroline)cobalt(III) trinitrate ethanol disolvate 1.87‐hydrate, [Co₂(C₄H₆N₂O₂)(C₄H₇N₂O₂)(C₁₂H₈N₂)₄](NO₃)₃·2C₂H₆O·1.87H₂O, (I), the C₂‐symmetric cation is formed with the coordination [Co(DMG)(phen)₂]⁺ cations aggregating via a very strong O⁻...H⁺...O⁻ hydrogen bond with an O...O distance of 2.409 (4) Å. Crystals of (I) exhibit extensive disorder of the solvent molecules, the nitrate anions and one of the phen ligands. Compound (I) is a kinetic product, not isolated previously from similar systems, that transforms slowly into (N‐hydroxy‐N′‐oxidobutane‐2,3‐diimine)bis(1,10‐phenanthroline)cobalt(III) dinitrate ethanol monosolvate 0.4‐hydrate, [Co(C₄H₇N₂O₂)(C₁₂H₈N₂)₂](NO₃)₂·C₂H₆O·0.40H₂O, (II), with the DMGH⁻ ligand hydrogen bonded to one of the nitrate anions. In (II), the solvent molecules and one of the nitrate anions are disordered.     

Clemizoledichlorocobalt(II)

The structure of di­chloro­[1‐(p‐chloro­benzyl)‐2‐(1‐pyrrol­idinyl­methyl‐N)‐1,3‐benz­imidazole‐N³]­cobalt(II), [Co­Cl₂(C₁₉­H₂₀ClN₃)], contains a mol­ecule of clemizole bound in a bidentate manner to cobalt through its imidazole and pyrrolidinyl N atoms, with significantly different Co—N distances of 1.976 (5) and 2.126 (5) Å, respectively. The geometry around cobalt is distorted tetrahedral, with significantly different Co—Cl distances of 2.217 (2) and 2.233 (2) Å, and the pyrrolidinyl ring is disordered.     

Field‐Induced Single‐Ion Magnetic Behavior in Two Mononuclear Cobalt(II) Complexes

The employment of a new rigid N‐tridentate ligand, bis(1‐chloroimidazo[1,5‐a]pyridin‐3‐yl)pyridine (bcpp), in the construction of cobalt(II) single‐ion magnets is reported. Two cobalt(II) complexes, [Co(bcpp)Cl₂] ( 1 ) and [Co(bcpp)Br₂] ( 2 ), have been prepared and characterized. Single‐crystal XRD analyses reveal that complexes 1 and 2 are isostructural. They are pentacoordinated mononuclear cobalt(II) compounds with expected trigonal bipyramidal geometry. Both analysis of the magnetic data and ab initio calculations reveal easy‐plane magnetic anisotropy (D>0) for 1 and 2 . Detailed alternating current magnetic susceptibility measurements reveal the occurrence of slow magnetic relaxation behavior for the cobalt(II) centers of 1 and 2 ; thus indicating that both complexes are field‐induced single‐ion magnets.     

A novel cobalt(II) coordination polymer containing the fumarate anion and o‐phenanthroline

The self‐assembly of three crystallographically distinct fumar­ate ions, two unique cobalt(II) ions and two unique o‐phen­;anthroline mol­ecules results in a two‐dimensional polymeric structure with the formula [Co₂(C₄H₂O₄)₂(C₁₂H₈N₂)₂]_n, namely di‐μ‐fumatato‐bis(o‐phenanthroline)­dicobalt(II). The Co atoms are at the nodes of a two‐dimensional array linked by coordinated fumarate ligands. Each Co atom is coordinated in a distorted octahedral manner to four fumarate O atoms and two N atoms from the chelating phenanthroline ligands.     

A novel cobalt(II) coordination polymer with an unusual four‐connected 42.63.8 topology

In the cobalt(II) coordination polymer poly[[(μ₂‐benzene‐1,3‐dicarboxylato){μ₂‐1,1′‐[2,2′‐oxybis(ethane‐2,1‐diyl)]di‐1H‐imidazole}cobalt(II)] monohydrate], {[Co(C₁₀H₁₄N₄O)(C₈H₄O₄)]·H₂O}_n, two crystallographically distinct Co^II cations are four‐coordinated by N₂O₂ donor sets in distorted tetrahedral geometries. The Co^II centers are connected by benzene‐1,3‐dicarboxylate (m‐BDC) anions, giving two types of linear chains, which are further joined via meso‐helical 1,1′‐[2,2′‐oxybis(ethane‐2,1‐diyl)]di‐1H‐imidazole ligands to yield a thick two‐dimensional slab. The compound displays a two‐dimensional four‐connected 4².6³.8 topology, which is unprecedented in coordination polymers.     

INTERACTIONS OF COBALT(II) TETRASULFOPHTHALOCYANINE WITH NITRITE IN THE PRESENCE OF NITRATE AND PERCHLORATE IONS

Abstract

Spectroscopic changes observed on addition of nitrite to solutions of cobalt(II) tetra-sulfophthalocyanine ([Co(II)TSPc]^4-) in the presence of N^? ₃ or ClO^? ₄ are reported. There is spectroscopic evidence for the oxidation of [Co(II)TSPc]^4- to a [Co(III)TSPc]^3- species in the presence of nitrite ions. Equilibrium and kinetic studies for the interaction between [Co(II)TSPc]^4- and NO^? ₂ are reported. The rate was found to be first order in both [Co(II)TSPc]^4- and NO^? ₂. The rate constant for the forward reaction, k _f=1.6 × 10^?4 dm³mol^?1s^?1 was determined at 20°C for the interaction between nitrite ions and [Co(II)TSPc]^4- in the presence of NO₃ ^? or ClO₄ ^? ions.     

catena‐Poly[[[N,N′‐bis­(salicyl­idene)propane‐1,3‐diaminato]cobalt(III)]‐μ‐azido] and catena‐poly[[[N,N′‐bis(salicyl­idene)propane‐1,3‐diaminato]cobalt(III)]‐μ‐thio­cyanato]

The two title complexes, catena‐poly[[{2,2′‐[1,3‐propane­diylbis(nitrilo­methyl­idyne)]diphenolato}cobalt(III)]‐μ‐azido], [Co(C₁₇H₁₆N₂O₂)(N₃)]_n, (I), and catena‐poly[[{2,2′‐[1,3‐propane­diylbis(nitrilo­methyl­idyne)]diphenolato}cobalt(III)]‐μ‐thio­cyanato], [Co(C₁₇H₁₆N₂O₂)(NCS)]_n, (II), are isomorphous polynuclear cobalt(III) compounds. In both structures, the Co^III atom is six‐coordinated in an octa­hedral configuration by two N atoms and two O atoms of one Schiff base, and two terminal N or S atoms from two bridging ligands. The [N,N′‐bis­(salicyl­idene)propane‐1,3‐diaminato]cobalt(III) moieties are linked by the bridging ligands, viz. azide in (I) and thio­cyanate in (II), giving zigzag polymeric chains with backbones of the type [–Co—N—N—N—Co]_n in (I) or [–Co—N—C—S—Co]_n in (II) running along the c axis.     

A Two‐Coordinate Cobalt(II) Imido Complex with NHC Ligation: Synthesis,Structure, and Reactivity

The synthesis, structural characterization, and reactivity of the first two‐coordinate cobalt complex featuring a metal–element multiple bond [(IPr)Co(NDmp)] ( 4 ; IPr=1,3‐bis(2′,6′‐diisopropylphenyl)imidazole‐2‐ylidene; Dmp=2,6‐dimesitylphenyl) is reported. Complex 4 was prepared from the reaction of [(IPr)Co(η²‐vtms)₂] (vtms=vinyltrimethylsilane) with DmpN₃. An X‐ray diffraction study revealed its linear C? Co? N core and a short Co? N distance (1.691(6) Å). Spectroscopic characterization and calculation studies indicated the high‐spin nature of 4 and the multiple‐bond character of the Co? N bond. Complex 4 effected group‐transfer reactions to CO and ethylene to form isocyanide and imine, respectively. It also facilitated E? H (E=C, Si) σ‐bond activation of terminal alkyne and hydrosilanes to produce the corresponding cobalt(II) alkynyl and cobalt(II) hydride complexes as 1,2‐addition products.     

A Two‐Coordinate Cobalt(II) Imido Complex with NHC Ligation: Synthesis,Structure, and Reactivity

The synthesis, structural characterization, and reactivity of the first two‐coordinate cobalt complex featuring a metal–element multiple bond [(IPr)Co(NDmp)] ( 4 ; IPr=1,3‐bis(2′,6′‐diisopropylphenyl)imidazole‐2‐ylidene; Dmp=2,6‐dimesitylphenyl) is reported. Complex 4 was prepared from the reaction of [(IPr)Co(η²‐vtms)₂] (vtms=vinyltrimethylsilane) with DmpN₃. An X‐ray diffraction study revealed its linear C Co N core and a short Co N distance (1.691(6) Å). Spectroscopic characterization and calculation studies indicated the high‐spin nature of 4 and the multiple‐bond character of the Co N bond. Complex 4 effected group‐transfer reactions to CO and ethylene to form isocyanide and imine, respectively. It also facilitated E H (E=C, Si) σ‐bond activation of terminal alkyne and hydrosilanes to produce the corresponding cobalt(II) alkynyl and cobalt(II) hydride complexes as 1,2‐addition products.     

Spectroscopic studies and determination of the formation constants and thermodynamic parameters for a new water-soluble Co(II) Schiff-base complex and some imidazole derivatives

A new water-soluble Co(II) Schiff-base complex, sodium[{N,N′-bis(5-sulfosalicylidene)-1,8-diamino-3,6-dioxaoctan}cobalt] dihydrate, abbreviated as Na₂[Co(II)L], was synthesized and characterized. The formation constants and thermodynamic parameters for the interaction of this complex with imidazole (Im) and 1-methylimidazole (MeIm) were determined spectroscopically in aqueous solution, ethanol/water (10/90), and methanol/water (10/90) under physiological conditions (pH?=?7), constant ionic strength (I?=?0.1?mol?dm^?3 KNO₃), and various temperatures ranging from 294 to 310?K. Our spectroscopic and thermodynamic results show that this adduct formation is endothermic and the positive values of ΔS _f° make ΔG _f° negative. The trend in variation of ΔH _f° and ΔS _f° for Im is in the order water?>?methanol?>?ethanol, but for MeIm it is in the opposite order which is related to the hydrogen bonding between solvents and these donors. Formation constants between MeIm and Na₂[Co(II)L] in these three solvents are larger than for Im which depends on the electron donation of methyl on MeIm.     

Nitro‐substituted iron(II) tridentate bis(imino)pyridine complexes as high‐temperature catalysts for the production of α‐olefins

A new series of nitro‐substituted bis(imino)pyridine ligands {2,6‐bis[1‐(2‐methyl‐4‐nitrophenylimino)ethyl]pyridine, 2,6‐bis[1‐(4‐nitrophenylimino)ethyl]pyridine, (1‐{6‐[1‐(4‐nitro‐phenylimino)‐ethyl]‐pyridin‐2‐yl}‐ethylidene)‐(2,4,6‐trimethyl‐phenyl)‐amine, and 2,6‐bis[1‐(2‐methyl‐3‐nitrophenylimino)ethyl]pyridine} and their corresponding Fe(II) complexes [{p‐NO₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐ Me? p‐NO₂}FeCl₂ ( 10 ), L₂FeCl₂ ( 11 ), {m‐NO₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me? m‐NO₂}FeCl₂ ( 12 ), and {p‐NO₂? Ph? N?C(Me)? Py? C(Me)?N? Mes}FeCl₂ ( 14 )] were synthesized. According to X‐ray analysis, there were shortenings of the axial Fe? N bond lengths (up to 0.014 Å) in para‐nitro‐substituted complex 10 and (up to 0.015 Å) in meta‐nitro‐substituted complex 12 versus the Fe(II) complex without nitro groups [{o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me}FeCl₂ ( 1 )]. Complexes 10 , 12 , and 14 afforded very active catalysts for the production of α‐olefins and were more temperature‐stable and had longer lifetimes than parent non‐nitro‐substituted Fe(II) complex 1 . The reaction between FeCl₂ and a sterically less hindered ligand [p‐NO₂? Ph? N?C(Me)? Py? C(Me)?N? Ph? p‐NO₂] resulted in the formation of octahedral complex 11 . A para‐dialkylamino‐substituted bis(imino)pyridine ligand [p‐NEt₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me? p‐NEt₂] and the corresponding Fe(II) complex [{p‐NEt₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me? p‐NEt₂}FeCl₂ ( 16 )] were synthesized to evaluate the effect of enhanced electron donation of the ligand on the catalytic performance. According to X‐ray analysis, there was a shortening (up to 0.043 Å) of the axial Fe? N bond lengths in para‐diethylamino‐substituted complex 16 in comparison with parent Fe(II) complex 1 . © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2615–2635, 2006     

o‐Chloro‐ and o‐bromo­benzonitrile: pseudosymmetry and pseudo‐isostructural packing

The structures of o‐chloro­benzonitrile, C₇H₄ClN, (I), and o‐bromo­benzonitrile, C₇H₄BrN, (II), have similar packing arrangements, even though Z′ = 4 in (I) and Z′ = 1 in (II). Both structures involve X⋯N inter­actions, as well as weak C—H⋯X and C—H⋯N hydrogen bonds. The four crystallographically independent mol­ecules in (I) are related by pseudosymmetry.     

Compounds of glycine with metal sulfates and thio­sulfates: glycine cobalt sulfate penta­hydrate,glycine sodium thio­sulfate dihydrate and glycine potassium thio­sulfate

In the crystal structures of the title compounds, hexa­aqua­cobalt(II) tetra­aqua­diglycinato­cobalt(II) bis(sulfate), [Co(H₂O)₆][Co(C₂H₅NO₂)₂(H₂O)₄](SO₄)₂, (I), poly[diaqua‐μ₃‐glycinato‐di‐μ₄‐thio­sulfato‐tetra­sodium(I)], [Na₄(C₂H₅NO₂)(S₂O₃)₂(H₂O)₂]_n, (II), and poly[μ₂‐glycinato‐μ₄‐thio­sulfato‐dipotassium(I)], [K₂(C₂H₅NO₂)(S₂O₃)]_n, (III), all atoms are located on general positions, except the Co atoms in (I), which are located on inversion centres. In (I), hydrogen bonds play an important role, while the alkali thio­sulfate compounds are characterized by three‐dimensional frameworks of polyhedra. Relations to other compounds of glycine and metal sulfates are commented on.     

Two Four‐Coordinate and Seven‐Coordinate CoII Complexes Based on the Bidentate Ligand 1, 8‐Naphthyridine Showing Slow Magnetic Relaxation Behavior

For a long time, the cobalt(II) complex ([Co(napy)₄](ClO₄)₂) (napy=1, 8‐naphthyridine) has been considered as an eight‐coordinate complex without any structural proof. After careful considerations, two complexes [Co(napy)₂Cl₂] ( 1 ) and [Co(napy)₄](ClO₄)₂ ( 2 ) based on the bidentate ligand napy were synthesized and structurally characterized. X‐ray single‐crystal structural determination showed that the cobalt(II) center in [Co(napy)₂Cl₂] ( 1 ) is four‐coordinate with a tetrahedral geometry (T_d), while [Co(napy)₄](ClO₄)₂ ( 2 ) is seven‐coordinate rather than eight‐coordinate with a capped trigonal prism geometry (C_2v). Direct‐current (dc) magnetic data revealed that complexes 1 and 2 possess positive zero‐field splitting (ZFS) parameters of 11.08 and 25.30 cm^?1, respectively, with easy‐plane magnetic anisotropy. Alternating current(ac) susceptibility measurements revealed that both complexes showed slow magnetic relaxation behaviour. Theoretical calculations demonstrated that the presence of easy‐plane magnetic anisotropy (D>0) for complexes 1 and 2 is in agreement with the experimental data. Furthermore, these results pave the way to obtain four‐coordinate and seven‐coordinate cobalt(II) single‐ion magnets (SIMs) by using a bidentate ligand.