Synthesis,Characterization, and Magnetic Behaviour of Dinuclear Nickel(II) Complexes of N,N′‐Substituted Dithiooxamides derived from α‐Amino Acids

New dinuclear complexes of the types [Ni₂(L)(H₂O)₂] and [Ni₂(L)(H₂O)₆] [H₄L = N,N′‐bis(carboxymethyl) dithiooxamide (H₄GLYDTO), N,N′‐bis(1‐carboxyethyl) dithiooxamide (H₄ALADTO), N,N′‐bis(1‐carboxy‐2‐methylpropyl) dithiooxamide (H₄VALDTO) and N,N′‐bis(1‐carboxy‐3‐methylbutyl) dithiooxamide (H₄LEUDTO)] have been prepared and characterized by IR and electronic absorption spectroscopy, and the structure of [Ni₂(ALADTO)(H₂O)₆] crystals has been determined by single crystal X‐ray analysis. This compound is composed of discrete dinuclear units in which two Ni^II atoms with NO₄S kernels are linked by a single [ALADTO]^4– group that coordinates through its carboxylato oxygen, amino nitrogen and thiolato sulphur atoms. In each dimer unit the two nickel(II) ions in distorted octahedral coordination are separated by 5.863(2) Å The temperature dependence of the magnetic susceptibility of the new compounds was measured over the range 2 to 300 K. In the complexes of [GLYDTO]^4– and [ALADTO]^4– the two Ni atoms are antiferromagnetically coupled, with J = –23.51(4) and –20.95(8) cm^–1, respectively. By constrast, [Ni₂(VALDTO)(H₂O)₂], [Ni₂(VALDTO)(H₂O)₆] and [Ni₂(LEUDTO)(H₂O)₂] remain paramagnetic down to 2 K, with magnetic moment values between 2.8 and 3.3 M.B.     

Magnetic Interactions through Imidazolate‐Bridges: Synthesis,Spectroscopy, Crystal Structure and Magnetic Properties of μ‐Imidazolato‐Bridged Copper(II) Complexes

The synthesis, characterization and crystal structures of substituted imidazolate bridged binuclear copper(II) complexes, [Cu₂(dien)₂(L)](ClO₄)₃, where dien = diethylenetriamine, L = imidazolate (im^—) ( 1 ), 2‐methylimidazolate (mim^—) ( 2 ) and benzimidazolate (bim^—) ( 3 ), are reported. The copper(II) ions of 1 — 3 posses a square planar coordination environment with dien coordinating as a tridentate ligand and the fourth position being occupied by a nitrogen atom of the bridging μ‐imidazolato group. In all three compounds the tendency to form additional long apical bonds at the copper(II) ions to the oxygen atoms of the perchlorate anions is observed. Temperature depended susceptibility data of polycrystalline samples reveal an antiferromagnetic coupling of the copper(II) atoms in 1 — 3 with J = —63.8, —75.4 and —36.8 cm^—1, respectively. Significant changes for these coupling constants could not be observed for measurements on frozen aqueous solutions. ESR spectra for solids and frozen solutions are consistent with intramolecular antiferromagnetic exchange interaction between the metal ions. From the data reported it can be concluded that the predominate mechanism for transmitting exchange coupling through the imidazolate bridge is due to a σ exchange pathways.     

Synthesis,Structure, and Magnetic Properties of a Copper(II) Metal‐Organic Framework with Biphenyl‐2,2′,4,4′‐tetracarboxylic Acid

The 2D Cu^II metal‐organic framework [Cu₂(bptc)(H₂O)₄]_n · 4nH₂O ( 1 ) (H₄bptc = biphenyl‐2,2′,4,4′‐tetracarboxylic acid) was hydrothermally synthesized and characterized by single‐crystal X‐ray diffraction and magnetic measurements. In the structure, bptc^4– serves as a twisted Π‐shaped organic building block to connect paddlewheel [Cu₂(COO)₄] dinuclear units and mononuclear units through 2‐/2′‐carboxylate and 4‐/4′‐carboxylate, respectively. According to the magnetic analysis using a dimer‐plus‐monomer model, strong antiferromagnetic coupling is operative within the dinuclear unit (J = –311 cm^–1 based on H = –J S ₁ S ₂), and the compound behaves like a mononuclear molecule at low temperature.     

Magnetic Exchange Interactions in Dinuclear Copper(II) and Nickel(II) Complexes with μ‐Oxalato Bridges. The Structure of μ‐Oxalato(O,O′, O″, O‴)‐bis{[1, 8‐di(2‐pyridyl)‐3, 6‐dithiaoctane‐N,N′, S,S′]nickel(II)} Dinitrate Dihydrate

A copper(II) and two nickel(II) dinuclear oxalato‐bridged compounds of formulae [{Cu(bpdto)}₂(μ‐ox)](ClO₄)₂ ( 1 ), [{Ni(bpdto)]₂(μ‐ox)](ClO₄)₂( 2 ), and [{Ni(bpdto)}₂(μ‐ox)](NO₃)₂·2H₂O ( 3 ), where bpdto = 1, 8‐bis(2‐pyridyl)‐3, 6‐dithiaoctane and ox = oxalate = C₂O₄^2— anion, have been synthesized and characterized. The crystal structure of 3 was determined by single‐crystal X‐ray analysis. It is a dinuclear complex with i symmetry in which the oxalate ligand is coordinated in bis(didentate) fashion to the inversion centre‐related nickel atoms. The distorted octahedral environment of each nickel atom is completed by two sulphur atoms in the equatorial plane and by two pyridyl nitrogen atoms in axial positions. Magnetic susceptibility measurements over the range 5 — 299K, show antiferromagnetic interactions that are weak in 1 (J = —12.8 cm^—1) and strong in 2 and 3 (J = —37.8 and —40.9 cm^—1, respectively), which in the case of 3 is in keeping with the observed structural parameters.     

Supramolecular Stuctures from Mononuclear,Binuclear and 2D Net of Copper(II) Complexes with 6‐Hydroxypicolinic Acid

First examples of transition metal complexes with HpicOH [Cu(picOH)₂(H₂O)₂] ( 1 ), [Cu(picO)(2,2′‐bpy)]·2H₂O ( 2 ), [Cu(picO)(4,4′‐bpy)_0.5(H₂O)]_n ( 3 ), and [Cu(picO)(bpe)_0.5(H₂O)]_n ( 4 ) (HpicOH = 6‐hydroxy‐picolinic acid; 2,2′‐bpy = 2,2′‐bipyridine; 4,4′‐bpy = 4,4′‐bipyridine; bpe = 1,2‐bis(4‐pyridyl)ethane) have been synthesized and characterized by single‐crystal X‐ray diffraction. The results show that HpicOH ligand can be in the enol or ketonic form, and adopts different coordination modes under different pH value of the reaction mixture. In complex 1 , HpicOH ligand is in the enol form and adopts a bidentate mode. While in complexes 2 – 4 , as the pH rises, HpicOH ligand becomes in the ketonic form and adopts a tridentate mode. The coordination modes in complexes 1 – 4 have not been reported before. Because of the introduction of the terminal ligands 2,2′‐bpy, complex 2 is of binuclear species; whereas in complexes 3 and 4 , picO ligands together with bridging ligands 4,4′‐bpy and bpe connect Cu^II ions to form 2D nets with (12³)₂(12)₃ topology.     

Dinuclear Five‐Coordinate Copper(II) Complexes with Chelating Diphosphonic Acid Ligands: Hydrothermal Synthesis,Structure, and Thermal Properties

The synthesis of two new diphosphonic acid ligands,[ethane‐1, 2‐diylbis(azanediyl)]bis[(4‐chlorophenyl)methylene]diphosphonic acid (L₁P), [ethane‐1, 2‐diylbis(azanediyl)]bis[(4‐bromophenyl)methylene]diphosphonic acid (L₂P), and their corresponding copper complexes, Cu₂(L₁P)₂ ( 1 ) and Cu₂(L₂P)₂ ( 2 ) are described herein. Complex 2 was structurally characterized with X‐ray single crystal diffraction. The structure of 2 consists of five‐coordinatecopper(II) ions with a distorted square pyramidal arrangement doubly bridged by OPO from phosphonate groups. The Cu–Cu distance is 4.7810(2) Å. The crystal packing is determined by interdinuclear hydrogen bonds, which lead to one‐dimensional chains. The results of thermogravimetric investigations (TG‐DTA), UV/Vis diffuse reflectance, infrared and (¹H and ¹³C) NMR spectroscopy, as well as elemental analyses of compounds 1 and 2 are also presented.     

Synthesis,Structure, and Spectroscopic Properties of Copper(II) and Nickel(II) Complexes Containing the 1, 4, 7‐Triisopropyl‐1, 4, 7‐triazacyclononane Ligand

Three new complexes [CuL(N₃)₂] ( 1 ), [CuL(SCN)₂] ( 2 ), and [NiL(SCN)₂] ( 3 ) (L = 1, 4, 7‐triisopropyl‐1, 4, 7‐triazacyclononane, [—NR—C₂H₄—NR—C₂H₄—NR—C₂H₄—], R = i‐Pr) have been synthesized and structurally characterized. The three complexes all crystallize in the monoclinic space group P2₁/n, with the unit cell parameters a = 9.100(5), b = 19.492(11), c = 11.646(6)Å, β = 94.526(9)° for 1 , a = 10.148(3), b = 13.611(5), c = 15.777(6)Å, β = 95.412(6)° for 2 and a = 9.270(7), b = 16.629(14), c = 14.886(12)Å, β = 101.217(15)° for 3 . The central copper(II) and nickel(II) ions are coordinated to five nitrogen atoms, three of which from the L and two from N₃^— or SCN^—, forming a slightly distorted square pyramidal geometry. Moreover, elemental analysis, IR, UV‐vis and ESR spectra of complexes 1 ‐ 3 were also determined.     

Synthesis and Characterization of N,N‐Di‐substituted Acylthiourea Copper(II) Complexes

A series of six N,N‐di‐substituted acylthiourea ArC(O)NHC(S)NRR′ ligands (denoted as HLⁿ) [Ar = 1‐Naph: NRR′ = NPh₂, HL¹ ( 1 ); N(iPr)Ph, HL² ( 2 ). Ar = Mes: NRR′ = NPh₂, HL⁴ ( 3 ); N(iPr)Ph, HL⁵ ( 4 ); NEt₂, HL⁶ ( 5 ). Ar = Ph: NRR′ = N(iPr)Ph, HL⁸ ( 6 )] were synthesized and characterized. These ligands were deprotonated to form Cu^II complexes through metathesis or combined redox reaction with copper halides. The structures of the complexes were investigated with single‐crystal X‐ray diffraction. The reaction of the 1‐naphthalene derivative HL¹ ( 1 ) with CuBr in the presence of sodium acetate produced cis‐CuL¹₂ ( 7 ), where the deprotonated ligand is bound to the Cu^II atom in a bidentate‐(O, S) coordination mode. Similarly treatment of HL² ( 2 ) with NaOAc and CuCl resulted in the formation of the cis‐arranged product [cis‐CuL²₂ ( 8 )]. The reaction of mesityl derivative HL⁴ ( 3 ) and CuBr with and without the addition of NaOAc gave the cis‐CuL⁴₂ ( 9 ) and cis‐(HL⁴)₂CuBr ( 10 ), respectively. In contrast, reaction of HL⁵ ( 4 ) and CuI in the presence of NaOAc resulted in trans‐CuL⁵₂ ( 11 ). Alternatively trans‐CuL⁶₂ ( 12 ) was obtained by the reaction of diethyl‐substituted HL⁶ ( 5 ) with CuCl₂ in the absence of a base.     

Synthesis,Characterization, and Magnetic Properties of Novel Cobalt(II) and Copper(II) Complexes with 5‐(Isonicotinamido)isophthalate Ligand

Two new complexes, {[Co(INAIP) · H₂O] · 2H₂O}_n ( 1 ), and {[Cu(INAIP)] · H₂O}_n ( 2 ) [H₂INAIP = 5‐(isonicotinamido)isophthalic acid] were synthesized under hydrothermal conditions, and characterized by single‐crystal X‐ray structure determination, thermogravimetric analysis, X‐ray powder diffraction, and magnetic studies. In complex 1 both Co^II atoms and INAIP^2– ligands act as four‐connected node, whereas in 2 both Cu^II atoms and INAIP^2– ligands act as three‐connected node.     

Double End‐On Azido Copper(II) Dinuclear Complex with Oxazoline Ligand: Synthesis,Structure, Magnetic Properties and Theoretical Study

A double azido‐bridged Cu^II dinuclear complex with the chelating chiral ligand, [Cu₂(L)₂(N₃)₄] ( 1 ) [L = (+)‐2, 2′‐isopropylidene‐bis((4R)‐4‐benzyl‐2‐oxazoline)] was synthesized and characterized by single‐crystal X‐ray diffraction, IR spectroscopy, magnetic measurements, and theoretical studies. The asymmetric double end‐on azido bridges in complex 1 lead to a weak antiferromagnetic behavior with J = –7.4 cm^–1. The exchange interactions in complex 1 were investigated by DFT calculations, and the calculated exchange interaction (J = –8.0 cm^–1) is in good agreement with the experimental value.     

Assemblies of 1D and 2D Copper(II) Chiral Coordination Polymers by Salicylaldehyde Schiff Bases: Synthesis,Crystal Structures,and Magnetic Properties

Reaction of CuCl₂ · 2H₂O with chiral Schiff bases and sodium dicyanamide led to the formation of two chiral copper(II) coordination polymers, namely [Cu₄(L¹)₂(dca)₄]_n ( 1 ) and [Cu₂(L²)(μ‐Cl)(dca)(H₂O)]_n · nH₂O ( 2 ) {H₂L¹ = (1R, 3S)‐N′,N′′‐bis[salicylidene]‐1,3‐diamino‐ 1,2,2‐trimethylcyclopentane, H₂L² = (1R, 3S)‐N′,N′′‐bis[3‐ethoxysalicylidene]‐1,3‐diamino‐ 1,2,2‐trimethylcyclopentane, dca = dicyanamide}. Both complexes were structurally characterized by elemental analyses, IR spectroscopy and single‐crystal X‐ray diffraction. Complex 1 exhibits a two‐dimensional polymeric structure formed by single dca bridging tetranuclear Cu₄ units. Complex 2 displays a left‐handed helical chain structure constructed from Cu₂ dimers with single dca bridges. The chirality of 1 and 2 was confirmed by circular dichroism (CD) measurements in solution. Both complexes exhibit strong antiferromagnetic couplings with J = –308(4) cm^–1 for 1 and J = –123(1) cm^–1 for 2 in 2–300 K.     

Mixed‐Ligand Complexes of Copper(II) with α‐Hydroxycarboxylic Acids and 1,10‐Phenanthroline

Eight new two‐ligand complexes of copper(II) with 1,10‐phenanthroline and one of four different α‐hydroxy‐carboxylic acids (glycolic, lactic, mandelic and benzylic) were prepared. The complexes of general formula [Cu(HL)₂(phen)] · nH₂O (HL = monodeprotonated acid) ( 1 – 4 ) were characterized by elemental analysis, IR, electronic and EPR spectroscopy, magnetic measurements and thermo‐gravimetric analysis. The complexes of general formulae [Cu(HL)(phen)₂](HL) · H₂L · nSolv [ 1 a (HL = HGLYO^–, n = 1, Solv = MeCN) and 3 a (HL = HMANO^–, n = 0)] and [Cu(L)(phen)(OH₂)] · nH₂O [ 2 a (L = LACO^2–, n = 4) and 4 a (L = BENO^2–, n = 2)] were characterized by X‐ray diffractometry. In all these latter a pentacoordinated copper atom has a basically square pyramidal coordination polyhedron, the distortion of which towards a trigonal bipyramidal configuration has been evaluated in terms of the parameter τ. In 1 a and 3 a there are three forms of α‐hydroxycarboxylic acid: a monodentate monoanion, a monoanionic counterion, and a neutral molecule lying in the outer coordination sphere; in 2 a and 4 a the α‐hydroxycarboxylic acid is a bidentate dianion coordinating through carboxyl and hydroxyl oxygens.     

Copper(II) and Cadmium(II) Complexes Based on N,N‐Bis(3, 5‐dimethyl‐2‐hydroxybenzyl)‐N‐(2‐pyridylmethyl)amine Ligand: Syntheses,Structures, Magnetic,and Luminescent Properties

The reaction of the aryl‐oxide ligand H₂L [H₂L = N,N‐bis(3, 5‐dimethyl‐2‐hydroxybenzyl)‐N‐(2‐pyridylmethyl)amine] with CuSO₄ · 5H₂O, CuCl₂ · 2H₂O, CuBr₂, CdCl₂ · 2.5H₂O, and Cd(OAc)₂ · 2H₂O, respectively, under hydrothermal conditions gave the complexes [Cu(H₂L¹)₂] · SO₄ · 3CH₃OH ( 1 ), [Cu₂(H₂L²)₂Cl₄] ( 2 ), [Cu₂(H₂L²)₂Br₄] ( 3 ), [Cd₂(HL)₂Cl₂] ( 4 ), and [Cd₂(L)₂(CH₃COOH)₂] · H₂L ( 5 ), where H₂L¹ [H₂L¹ = 2, 4‐dimethyl‐6‐((pyridin‐2‐ylmethylamino)methyl)phenol] and H₂L² [H₂L² = 2‐(2, 4‐dimethyl‐6‐((pyridin‐2‐ylmethylamino)methyl)phenoxy)‐4, 6‐dimethylphenol] were derived from the solvothermal in situ metal/ligand reactions. These complexes were characterized by IR spectroscopy, elementary analysis, and X‐ray diffraction. A low‐temperature magnetic susceptibility measurement for the solid sample of 2 revealed antiferromagnetic interactions between two central copper(II) atoms. The emission property studies for complexes 4 and 5 indicated strong luminescence emission.     

Synthesis,Structure, Magnetic and Electrochemical Properties of a Dinuclear Copper Complex

A material for both magnetic coupling and electrocatalytic hydrogen evolution based on the copper complex, [(L)₂Cu₂] is formed by the reaction of CuCl₂ · 2H₂O with the tetradentate ligand 6‐(3‐aminomethylpropanol)‐2‐tert‐buty‐4‐methylphenol (H₂L), which is prepared by reaction of 2‐tert‐butyl‐4‐methylphenol, 3‐amino‐1‐propanol, and formaldehyde. Structural studies show that in the solid state complex 1 exhibits strong antiferromagnetic exchange interaction between copper(II) ions mediated by oxygen‐bridges. In liquid, 1 becomes a monomer, and can electrocatalyze hydrogen generation both from acetic acid with a turnover frequency (TOF) of 101.70 mol of hydrogen per mole of catalyst per hour at an overpotential (OP) of 941.6 mV (in DMF), and a natural buffer with a TOF of 650 mol of hydrogen per mole of catalyst per hour at an OP of 836.7 mV.     

Cobalt(II) Complexes with N‐Thioacylamidophosphates and 2,2′‐Bipyridyl and 1,10‐Phenathroline. Crystal Structures,Solution 1H NMR Spectral and Magnetic Properties

Structure and magnetic properties of N‐diisopropoxyphosphorylthiobenzamide PhC(S)‐N(H)‐P(O)(OiPr)₂ ( HL^I ) and N‐diisopropoxyphosphoryl‐N′‐phenylthiocarbamide PhN(H)‐C(S)‐N(H)‐P(O)(OiPr)₂ ( HL^II ) complexes with the Co^II cation of formulas [Co{PhC(S)‐N‐P(O)(OiPr)₂}₂] ( 1 ), [Co{PhN(H)‐C(S)‐N‐P(O)(OiPr)₂}₂] ( 2 ), [Co{PhC(S)‐N(H)‐P(O)(OiPr)₂}₂{PhC(S)‐N‐P(O)(OiPr)₂}₂] ( 1a ) and [Co{PhC(S)‐N‐P(O)(OiPr)₂}₂}(2,2′‐bipy)] ( 3 ), [Co{PhC(S)‐N‐P(O)(OiPr)₂}₂(1,10‐phen)] ( 4 ), [Co{PhN(H)‐C(S)‐N‐P(O)(OiPr)₂}₂(2,2′‐bipy)] ( 5 ), [Co{PhN(H)‐C(S)‐N‐P(O)(OiPr)₂}₂(1,10‐phen)] ( 6 ) were investigated. Paramagnetic shifts in the ¹H NMR spectrum were observed for high‐spin Co^II complexes with HL^I,II , incorporating the S‐C‐N‐P‐O chelate moiety and two aromatic chelate ligands. Investigation of the thermal dependence of the magnetic susceptibility has shown that the extended materials 1‐2 and 6 show ferromagnetic exchange between distorted tetrahedral ( 1 , 2 ) or octahedral ( 1a , 6 ) metal atoms whereas 3 and 5 show antiferromagnetic properties. Compound 4 behaves as a spin‐canted ferromagnet, an antiferromagnetic ordering taking place below a critical temperature, T_c = 115 K. Complexes 1 and 1a were investigated by single crystal X‐ray diffraction. The cobalt(II) atom in complex 1 resides a distorted tetrahedral O₂S₂ environment formed by the C=S sulfur atoms and the P=O oxygen atoms of two deprotonated ligands. Complex 1a has a tetragonal‐bipyramidal structure, Co(O^ax)₂(O^eq)₂(S^eq)₂, and two neutral ligand molecules are coordinated in the axial positions through the oxygen atoms of the P=O groups. The base of the bipyramid is formed by two anionic ligands in the typical 1,5‐O,S coordination mode. The ligands are in a trans configuration.     

Synthesis,Crystal Structure,Thermal, Spectroscopic and Magnetic Properties of a 2D Grid‐like Copper(II) μ‐1,1 Isocyanato Coordination Polymer with Pyrazine Bridges

Reaction of copper(II) cyanate with pyrazine leads to the formation of [Cu(NCO)₂(pyrazine)]_n ( 1 ), in which the Cu²⁺ cations are coordinated by two nitrogen atoms of the pyrazine ligands, as well as by four nitrogen atoms of the cyanate anions within a slightly distorted octahedral coordination. In the crystal structure the Cu²⁺ cations are connected by the pyrazine ligands into chains which are further linked by the cyanate anions through asymmetric μ‐1,1‐NCO coordination into layers. On heating compound 1 transforms quantitatively to copper(II) cyanate which decompose to elemental copper on further heating. No ligand deficent intermediates are observed. Magnetic measurements reval an antiferromagnetic ordering at lower temperatures mediated by the π‐system of the aromatic pyrazine ligand as well as net ferromagnetic interactions mediated by the μ‐1,1‐NCO bridging cyanato anions. A search in the Cambridge Crystal Structure Database shows that the terminal coordination mode in cyanato complexes as well as their azido and thiocyanato analogs is obviously energetically favored. In addition, a comparison of their symmetric and asymmetric end‐on (μ‐1,1) as well as end‐to‐end (μ‐1,3) bridging modes reveal interesting correlations.     

Relaxometric Study of Copper [15]Metallacrown‐5 Gadolinium Complexes Derived from α‐Aminohydroxamic Acids

Proton nuclear magnetic relaxation dispersion (NMRD) profiles were recorded between 0.24 mT and 1.4 T for lanthanum(III )‐ and gadolinium(III )‐containing [15]metallacrown‐5 complexes derived from α‐aminohydroxamic acids and with copper(II ) as the ring metal. The influence of the different R‐groups on the proton relaxivity was investigated, and a linear relationship between the relaxivity and the molecular mass of the metallacrown complex was found. The selectivity of the metallacrown complexes was tested by transmetalation experiments with zinc(II ) ions. The crystal structure of the copper [15]metallacrown‐5 gadolinium complex with glycine hydroximate ligands is reported.     

Assembly of a Novel Dumbbell‐type Dinuclear Copper(II) Complex: Synthesis,Structure and Properties

A new dumbbell‐type 4,4′‐bipy‐bridged dinuclear copper(II) complex, [Cu₂(4,4′‐bipy)L₂(H₂O)₂](ClO₄)₄ · 8CH₃OH · 10H₂O, where L = 1‐[bis(3‐aminopropyl)amino]‐2‐ propanol and bipy = bipyridine, has been synthesized and characterized, X‐ray crystallographic analysis shows that the [Cu₂(4,4′‐bipy)L₂(H₂O)₂]⁴⁺ cations and water molecules generate layer structures extending parallel to bc planes through hydrogen bonding interactions of O–H ··· O and C–H ··· O. The layers are also connected by hydrogen bonding interactions involving methanol, water, and perchlorate anions. These interactions lead to the formation of rectangular channels of 12.3 Å × 6.0 Å along the crystallographic c axis. Perchlorate anions fill in each channel in a sandwich‐like packing mode, they are joined with the adjacent layers by water heptamers. Magnetic susceptibility measurements show that the magnetic exchange interaction is weak although it has a regular π‐type electron transfer pathway. Furthermore, the electrochemical and thermogravimetric properties of the complex were also investigated.     

Two Extended 5‐Methyltetrazolate‐Based Magnetic Complexes: Synthesis,Structure, and Magnetic Properties

Two 5‐methyl‐tetrazolate (mtz^–)‐based paramagnetic metal coordination polymers, {[Cu₂(H₂O)₂(mtz)(μ₃‐OH)(nip)] · H₂O}_n ( 1 ) and [Cu(H₂O)(mtz)₂]_n ( 2 ), were obtained in the presence and absence of aromatic 5‐nitroisophathalate (nip^2–) coligand by varying the preparation methods. Structural determinations reveal that 1 is a three‐dimensional (3D) framework with corner‐sharing triangular ribbons infinitely extended by ditopic nip^2– connectors. In contrast, 2 is a coplanar (4,4) layer constructed from square‐pyramidal Cu^II ions and μ‐N1,N4‐mtz^– linkers, which is further assembled into a 3D supramolecular network by interlayer hydrogen‐bonding interactions. Magnetically, spin‐frustrated antiferromagnetic ordering is observed in the 3D framework of 1 and canted antiferromagnetic behavior with a slight spin‐flop transition is presented in 2 , which are structurally resulting from the locally Δ‐ribbon in 1 and asymmetric magnetic superexchange mediated by the μ‐N1,N4‐mtz^– bridge of 2 .