Synthesis,Structure, and Magnetic Properties of a Dinuclear Antiferromagnetically Coupled Cobalt Complex

A new dinuclear cobalt(II) compound,[(TPA*)Co^II(DHBQ^2–)Co^II(TPA*)]²⁺ ( 1 ²⁺) {TPA* =tris[(3, 5‐dimethyl‐pyrazol‐l‐yl)methyl] amine, DHBQ = deprotonated 2, 5‐dihydroxy‐1, 4‐benzoquinone}, was prepared and structurally and magnetically characterized. X‐ray crystallography revealed the centrosymmetric dinuclear divalent cobalt ions bridged by DHBQ^2– unit. The cobalt ions in the title compound have a distorted octahedral arrangement by coordination with four nitrogens of a TPA* and two oxygens of a bridging DHBQ unit. Due to the interdimer offset face‐to‐face π–π stacking in the crystallographic ac plane, the complex shows extended 2D supramolecular structure. Magnetic experiments showed the cobalt‐based dinuclear compound exhibits antiferromagnetic interactions with g = 2.35 and J/k_B = –2.76 K, respectively.     

Effect of Organic Dicarboxylates with Different Rigidity on the Construction of Cobalt(II) Complexes with a Semi‐rigid Tripyridyl‐bis‐amide Ligand

Three coordination compounds with dimensions from 0D to 2D, namely, [Co(bppdca)₂(HL1)₂] ( 1 ) [Co(bppdca)(L2)(H₂O)] · 2H₂O ( 2 ) and [Co(bppdca)(L3)] · 3H₂O ( 3 ) [bppdca = N,N′‐bis(pyridine‐3‐yl)pyridine‐2,6‐dicarboxamide, H₂L1 = 2,5‐pyridinedicarboxylic acid, H₂L2 = 4,4′‐oxybisbenzoic acid, H₂L3 = 2‐carboxymethylsulfanyl nicotinic acid] were hydrothermally synthesized and structurally characterized. Single crystal X‐ray diffraction analysis reveals that complex 1 is a discrete 0D complex, in which the bppdca ligand and the H₂L1 act as the terminal groups to coordinate with the Co^II ions. In coordination polymer 2 , two bppdca ligands coordinate in anti configuration with two Co^II ions to generate a 28‐membered Co₂(bppdca)₂ loop, which is further extended into 1D ladder‐like double chain by pairs of L2 ligands. In 3 , the Co^II ions are linked by bppdca ligands to generate 1D wave‐like chain, which is further connected by the L3 to form a 2D network. Finally, the coordination compounds 1 – 3 are extended into 3D supramolecular frameworks through the hydrogen bonding interactions. The Co^II ions and the bppdca ligands in the title coordination compounds exhibit different coordination characters and conformations. The effect of organic dicarboxylates with different rigidity and length on the structures of Co^II coordination compounds was investigated. In addition, the fluorescence and electrochemical behaviors of coordination compounds 1 – 3 were reported.     

Two Coordination Polymers based on a Carboxylate‐­functionalized Imidazophenanthroline Derivative Ligand and Phthalic Acid: Syntheses,Structures and Magnetic Properties

Two coordination polymers, [Co₂(Hcpip)₂(phth)]_n · 3n(H₂O) ( 1 ) and [Mn₂(Hcpip)₂(phth)]_n ( 2 ), {H₂cpip = 2‐(2‐carboxyphenyl)imidazo[4,5‐f](1,10)‐ phenanthroline, H₂phth = phthalic acid}, were hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy, and single‐crystal X‐ray diffraction. Complex 1 is a 1D chain, in which the dinuclear [Co₂(Hcpip)₂]²⁺ units are linked through (phth)^2– anions. Complex 2 is a 2D layer structure, which is constructed from the 1D chains bridged by (phth)^2– anions. The magnetic properties of 1 and 2 show that the weak ferromagnetic interactions occurred between Co^II ions in 1 and a weak antiferromagnetic interactions exist between Mn^II ions in 2 . These two complexes have good thermal stabilities.     

Hydrothermal Syntheses and Crystal Structures of Two New Three‐dimensional Coordination Polymers Based on 4‐Pyrid‐3‐ylbenzoic Acid

Two new coordination polymers [Co₂(pbc)₄(H₂O)]_n ( 1 ) and [Mn(pbc)₂] ( 2 ) (Hpbc = 4‐pyrid‐3‐ylbenzoic acid) were obtained by hydrothermal reaction and characterized by elemental analysis, IR spectroscopy, and single‐crystal X‐ray diffraction. Compound 1 features a 3D network with a four‐connected 6⁶ net constructed from secondary building units of dinuclear cobalt. Compound 2 exhibits a six‐connected 4¹² · 6³ topology based on dinuclear manganese.     

Coordination Behavior of a D‐Penicillaminato Aurate(I) Metalloligand Toward Coblat(III) Centers

Treatment of (NH₄)[Au(D‐Hpen‐S)₂](D‐H₂pen = D‐penicillamine) with CoCl₂·6H₂O in an acetate buffer solution, followed by air oxidation, gave neutral Au^ICo^III and anionic Au^I₃Co^III₂ polynuclear complexes, [Au₃Co₃(D‐pen‐N,O,S)₆]([ 1 ]) and [Au₃Co₂(D‐pen‐N,S)₆]^3? ([ 2 ]^3?), which were separated by anion‐exchange column chromatography. Complexes [ 1 ] and [ 2 ]^3? each formed a single isomer, and their structures were determined by single‐crystal X‐ray crystallography. In [ 1 ], each of three [Au(D‐pen‐S)₂]^3?metalloligands coordinates to two Co^III ions in a bis‐tridentate‐N,O,S mode to form a cyclic Au^I₃Co^III₃ hexanuclear structure, in which three [Co(D‐pen‐N,O,S)₂]^? octahedral units and six bridging S atoms adopt trans(O) geometrical and R chiral configurations, respectively. In [ 2 ]^3?, each of three [Au(D‐pen‐S)₂]^3? metalloligands coordinates to two Co^III ions in a bis‐bidentate‐N,S mode to form a Au^I₃Co^III₂ pentanuclear structure, in which two [Co(D‐pen‐N,S)₃]^3? units and six bridging S atoms adopt ∧ and R chiral configurations, respectively.     

Structure and Magnetic Properties of A μ‐Phenoxido‐bridged Dinuclear Cobalt(II) Complex

A new dinuclear cobalt(II) complex [Co₂L₂Cl₂(CH₃OH)₂] ( 1 ), where HL = 3‐[(furan‐2‐ylmethylimino)methyl]‐2‐hydroxy‐5‐methylbenzaldehyde, derived from the in situ condensation of 2,6‐diformyl‐4‐methylphenol with furfurylamine, was prepared and structurally and magnetically characterized. Single crystal X‐ray structural determination reveals that the structure consists of centrosymmetric dinuclear units with each Co^II ion in a slightly distorted octahedral environment. Lines’ model, which in principle can theoretically separate in spin‐only and orbital contribution, was used to fit the variable temperature susceptibility (2–300 K), suggesting an intramolecular antiferromagnetic interaction between the cobalt(II) ions.     

Tetranuclear and One‐dimensional Cobalt Complexes with 5‐tert‐Butyl Isophthalic Acid and Chelating Neutral Ligands

Two new Co^II coordination polymers [Co₄(tbip)₄(bipy)₄(H₂O)₄] ( 1 ) and [Co(tbip)(phen)(H₂O)] · H₂O ( 2 ) (H₂tbip = 5‐tert‐butyl isophthalic acid, bipy = 2,2′‐bipyridine, phen = 1,10‐phenanthroline) have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, and single‐crystal X‐ray diffraction. Compound 1 is a tbip‐bridged tetranuclear cobalt(II) complex, which is further linked by hydrogen bonds to form a supramolecular network. Compound 2 shows a tbip‐bridged linear chain structure, which is extended by hydrogen bonds to generate a double chain. Magnetic measurements show that there are weak ferromagnetic interactions between the adjacent Co^II ions in 1 .     

Impact of Reaction Conditions on the Structures of Nickel(II) Complexes Based on 3‐(4‐Carboxyphenyl)propionic Acid

Two new nickel(II) complexes, [Ni(4, 4′‐bpy)(H₂O)₄]_n · n(cpp) · 0.5nH₂O ( 1 ) and [Ni(cpp)(4, 4′‐bpy)(H₂O)₂]_n ( 2 ) [4, 4′‐bpy = 4, 4′‐bipyridine, H₂cpp = 3‐(4‐carboxyphenyl)propionic acid] were synthesized and characterized by single‐crystal X‐ray diffraction, elemental analysis, IR spectroscopy, and thermal analysis. In complex 1 , Ni^II ions are bridged by 4, 4′‐bpy into 1D chains, and cpp ligands are not involved in the coordination, whereas in complex 2 , cpp ligands adopt a bis(monodentate) mode and link Ni^II ions into 2D (4, 4) grids with the help of 4, 4′‐bpy ligands. Triple interpenetration occurs, which results in the formation of a complicated 3D network. The difference in the structures of the two complexes can be attributed to the different reaction temperatures and bases.     

Structure and Magnetic Properties of a 2D Paddle‐wheel Dinuclear[Cu2] Cluster‐based Polymer with 1,1‐Cyclohexanediacetate Ligand

One new two‐dimensional (2D) Cu^II polymer [Cu(CHDA)(H₂O)]_n ( 1 ) was synthesized solvothermally based on 1,1‐cyclohexanediacetic acid (H₂CHDA) ligand. Single‐crystal X‐ray diffraction analysis reveals that 1 has a 2D framework structure consisting of paddle‐wheel dinuclear [Cu₂] cluster unit and CHDA^2– connector, which bears a 4‐connected sql network with Schläfli symbol of (4⁴.6²). Magnetic studies indicate the presence of strong antiferromagnetic coupling (J = –302 cm^–1) between the two Cu^II ions in the paddle‐wheel dicopper(II) entity.     

Three Transition Metal(II) Coordination Polymers Constructed by a Semi‐rigid Bis‐pyridyl‐bis‐amide and Dicarboxylates Mixed Ligands: Assembly,Structures and Properties

Three coordination polymers, namely [Co(BDC)( L )] · H₂O ( 1 ), [Co(NPH)( L )] · H₂O ( 2 ), and [Ni(NPH)( L )(H₂O)₃] · H₂O ( 3 ) [H₂BDC = 1, 3‐benzenedicarboxylic acid, H₂NPH = 3‐nitrophthalic acid, L = N,N′‐bis(3‐pyridyl)‐terephthalamide] were hydrothermally synthesized by self‐assembly of cobalt/nickel chloride with a semi‐rigid bis‐pyridyl‐bis‐amide ligand and two aromatic dicarboxylic acids. Single crystal X‐ray diffraction analyses revealed that complexes 1 and 2 are two‐dimensional (2D) coordination polymers containing a one‐dimensional (1D) ribbon‐like Co‐dicarboxylate chain and a 1D zigzag Co‐ L chain. Although the coordination numbers of Co^II ions and the coordination modes of two dicarboxylates are different in complexes 1 and 2 , they have a similar 3, 5‐connected {4².6⁷.8}{4².6} topology. In complex 3 , the adjacent Ni^II ions are linked by L ligands to form a 1D polymeric chain, whereas the 1D chains does not extend into a higher‐dimensional structure due to the ligand NPH with monodentate coordination mode. The adjacent layers of complexes 1 and 2 and the adjacent chains of 3 are further linked by hydrogen bonding interactions to form 3D supramolecular networks. Moreover, the thermal stabilities, fluorescent properties, and photocatalytic activities of complexes 1 – 3 were studied.     

An Extremely Porous Hydrogen‐Bonded Framework Composed of d‐Penicillaminato CoIII2AuI3 Complex Anions and Aqua Cobalt(II) Cations: Formation and Stepwise Structural Transformation

A unique example of a hydrogen‐bonded ionic solid with a porosity of 80 %, [Co(H₂O)₆]₃[Co₂Au₃(d ‐pen‐N,S)₆]₂ ( 1 ; d ‐H₂pen=d ‐penicillamine), composed of [Co(H₂O)₆]²⁺ cations and [Co₂Au₃(d ‐pen‐N,S)₆]^3? anions, is reported. Solid 1 was kinetically produced and was then transformed stepwise into two more thermodynamically stable solids with lower porosities, [Co(H₂O)₄][Co(H₂O)₆]₂[Co₂Au₃(d ‐pen‐N,S)₆]₂ ( 2 ) and [Co(H₂O)₄]₃[Co₂Au₃(d ‐pen‐N,S)₆]₂ ( 3 ), through the coordination of the free carboxylate groups in [Co₂Au₃(d ‐pen‐N,S)₆]^3? to Co^II centers. Solids 1 – 3 were structurally characterized, and the selective adsorption of small molecules into their pores was investigated.     

Size‐Selective Encapsulation of Hydrophobic Guests by Self‐Assembled M4L6 Cobalt and Nickel Cages

Subtle differences in metal–ligand bond lengths between a series of [M₄L₆]^4? tetrahedral cages, where M=Fe^II, Co^II, or Ni^II, were observed to result in substantial differences in affinity for hydrophobic guests in water. Changing the metal ion from iron(II) to cobalt(II) or nickel(II) increases the size of the interior cavity of the cage and allows encapsulation of larger guest molecules. NMR spectroscopy was used to study the recognition properties of the iron(II) and cobalt(II) cages towards small hydrophobic guests in water, and single‐crystal X‐ray diffraction was used to study the solid‐state complexes of the iron(II) and nickel(II) cages.     

Hydrothermal Synthesis of a 3D Polymeric Cobalt(II) Carboxylate Derivative from 1,2,4,5‐Benzenetetracarbonitrile

The metal‐organic complexes Co₂(terpy)₂(btec)·H₂O 1 (terpy = 2,2′:6′,2″‐terpyridine, btec = 1,2,4,5‐benzenetetracarboxylate) was synthesized by hydrothermal synthesis method, using 1,2,4,5‐benzenetetracarbonitrile, terpy and CoAc₂·4H₂O. Single crystal X‐ray diffraction showed that each btec^4– ligand links four Co^II atoms and each Co^II atom links to two btec^4– ligands forming a 1D double‐chain structure. Furthermore, the chains pack together through short face–face π–π interactions forming a 3D supramolecular structure. Additionally, the magnetic measurements show antiferromagnetic interactions among metal ions for compound 1 .     

Cobalt(II)‐Terephthalate Frameworks Containing Bis(benz­imidazole) Derivative Co‐ligands: Syntheses,Crystal Structures,Catalytic and Fluorescence Properties

Two metal‐organic coordination polymers of Co^II with the molecular formulae [Co(L₁)(tp)(H₂O)₂]_n ( 1 ) and [Co(L₂)(tp) · H₂O]_n ( 2 ) [L₁ = 1, 4‐bis(benzimidazole‐1‐ylmethyl)‐ benzene; L₂ = 1, 1‐(1, 4‐butanediyl)bis(5, 6‐dimethylbenzimidazole); tp = terephthalate] were synthesized and characterized by single‐crystal X‐ray diffraction studies, infrared spectroscopy (IR), thermogravimetric analysis (TGA), X‐ray powder diffraction (XRPD), and elemental analysis. The structure determination of complex 1 reveals a 2D layer with (4, 4) topology, with Co^II ions at the nodes connected through tp and L₁ co‐ligands. Complex 2 is the first example of a four‐connected SrAl₂ structure type ( sra , 4²6³8 topology) with threefold interpenetration in Co^II coordination frameworks, forming by bridging L₂ and tp co‐ligands. In addition, the fluorescence and catalytic performances of the complexes for the degradation of methyl orange were investigated.     

Two New Trinuclear MII (M = Mn,Co) Complexes Based on 2,4‐Dichlorobenzoic Acid: Synthesis,Structures and Magnetic Properties

Two new isostructural complexes, [Mn₃(L)₆(bipy)₂] ( 1 ) and [Co₃(L)₆(bipy)₂] ( 2 ) (L = 2,4‐dichlorobenzoate, bipy = 2, 2′‐bipyridine) were synthesized under the hydrothermal conditions and characterized by single‐crystal X‐ray diffraction, IR spectroscopy, EA (elemental analysis), and magnetic measurements. The two complexes are found to contain a trinuclear (M₃) unit that opens up a possibility of being magnetic materials. The magnetic measurements reveal that 1 exhibits the antiferromagnetic exchange interaction between metal ions and 2 presents a weak ferromagnetic interactions between the Co^II ions.     

Synthesis,Structures and Magnetic Properties of Two Binuclear Cobalt(II) Complexes Bridged by Bis(p‐nitrophenyl) Phosphate or Diphenylphosphinate Ion

Two new binuclear cobalt(II) complexes, [Co₂ L¹ (μ₂‐DPP)]²⁺ ( 1 ) (H L¹ = N, N, N′, N′‐ tetrakis (2‐benzimidazolylmethyl)‐2‐hydroxyl ‐1,3‐diaminopropane; DPP = diphenylphosphinate) and [Co₂ L² (μ₂‐BNPP)₂]⁺ ( 2 ) (H L² = 2,6‐bis‐[N,N‐di(2‐ pyridylmethyl)aminomethyl]‐4‐methylphenol, BNPP = bis(4‐nitrophenyl)phosphate) have been synthesized and their crystal structures and magnetic properties are shown. In 1 , each Co^II atom has a distorted trigonal bipyramidal coordination sphere with a N₃O₂ donor set and the central two Co^II atoms are bridged by one alkoxo‐O atom and one μ₂‐DPP ion with the Co1‐Co2 separation of 3.542Å. In 2 , each Co^II atom has a pseudo octahedral environment with a N₃O₃ donor set and the central two Co^II atoms are bridged by a phenolic oxygen atom of L² and two μ₂‐BNPP ions with the Co1‐Co2 separation of 3.667Å. Susceptibility data of 1 and 2 indicate intramolecular antiferromagnetic coupling of the high‐spin Co^II atoms.     

Two CdII/CoII‐Imidazolate Coordination Polymers: Syntheses,Crystal Structures,Stabilities, and Luminescent/Magnetic Properties

Cadmium(II) based 2D coordination polymer [Cd(L1)₂(DMF)₂] ( 1 ) (L1 = 4,5‐dicyano‐2‐methylimidazolate, DMF = N,N′‐dimethylformamide) and 2D cobalt(II)‐imidazolate framework [Co(L3)₄] ( 2 ) (L3 = 4,5‐diamide‐2‐ethoxyimidazolate) were synthesized under solvothermal reaction conditions. The materials were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, powder X‐ray diffraction measurement (PXRD) and single‐crystal X‐ray diffraction. Compound 1 has hexacoordinate Cd^II ions and forms a zigzag chain‐like coordination polymer structure, whereas compound 2 exhibits a 2D square grid type structure. The thermal stability analysis reveals that 2 showed an exceptional thermal stability up to 360 °C. Also, 2 maintained its fully crystalline integrity in boiling water as confirmed by PXRD. The solid state luminescent property of 1 was not observed at room temperature. Compound 2 showed an independent high spin central Co^II atom.     

Complexes of N‐Thiophosphorylthiourea tBuNHC(S)NHP(S)(OiPr)2 with Zinc(II), Cadmium(II), Nickel(II), and Cobalt(II) Cations

Reaction of the potassium salt of N‐thiophosphorylthiourea tBuNHC(S)NHP(S)(OiPr)₂ ( HL ) with Zn^II, Cd^II, Ni^II and Co^II in aqueous EtOH leads to complexes of common formula M(L‐S,S′)₂ ( ML₂ ). Complexes were investigated by IR, UV‐Vis, ¹H and ³¹P{¹H} NMR spectroscopy and microanalysis The structure of complex NiL₂ was investigated by single crystal X‐ray diffraction analysis. The nickel(II) ion has a squre‐planar environment, S₄, with two anionic ligands involving 1,5‐S,S′‐coordination mode. The ligands are bound in a trans configuration.     

Synthesis and Crystal Structure of Two Succinato‐Bridged Macrocyclic Nickel(II) Complexes

Two dinuclear succinato‐bridged nickel(II) complexes [Ni(RR‐L)]₂(μ‐SA)(ClO₄)₂ ( 1 ) and [Ni(SS‐L)]₂(μ‐SA)(ClO₄)₂ ( 2 ) (L = 5, 5, 7, 12, 12, 14‐hexamethyl‐1, 4, 8, 11‐tetraazacyclotetradecane, SA = succinic acid) were synthesized and characterized by EA, Circular dichroism (CD), as well as IR and UV/Vis spectroscopy. Single crystal X‐ray diffraction analyses revealed that the Ni^II atoms display a distorted octahedral coordination arrangement, and the succinato ligand bridges two central Ni^II atoms in a bis bidentate fashion to form dimers in 1 and 2 . The monomers of {[Ni(RR‐L)]₂(μ‐SA)}²⁺ and {[Ni(SS‐L)]₂(μ‐SA)}²⁺ are connected by O–H ··· O and N–H ··· O hydrogen bonds into a 1D right‐handed and left‐handed helical chain along the b axis, respectively. The homochiral natures of 1 and 2 are confirmed by the results of CD spectroscopy.     

A Pentanuclear Cobalt Complex with two [CoII(CH3O)3]– Units Wrapping a Triangular [CoIII3O]7+ Core: Synthesis,Structure, and Magnetic Properties

The reaction of Hppko (Hppko = phenyl 2‐pyridyl ketone oxime) and CoCl₂ · 6H₂O in the CH₃OH solvent with the presence of triethylamine (NEt₃) at room temperature and the exposure to air resulted in the formation of a new pentanuclear, mixed‐valence cobalt complex with the molecular formula [{Co^II(CH₃O)₃}₂{Co^III₃(μ₃‐O)(ppko)₃}Cl₂]. X‐ray single crystal analysis displays a trigonal bipyramid configuration with the terminal two Co^II ions wrapping an triangle [Co^III₃O]⁷⁺ core. The intermolecular C–H ··· O and C–H ··· Cl interactions form a 2D network framework. The analysis of magnetic susceptibility revealed the dominant antiferromagnetic interactions and strong orbital contribution of Co^II ions.