Synthesis,characterization and luminescent properties of three-coordinate copper(I) halide complexes containing 2-(diphenylphosphino)biphenyl

Highly emissive three-coordinate copper halide complexes with a bidentate phosphine ligand have attracted attention. Here, a series of three-coordinate mono- and dinuclear copper halide complexes, [CuI(dpbp)₂] (1) and [CuX(dpbp)]₂ (dpbp = 2-(diphenylphosphino)biphenyl, X = Br (2), Cl (3)), were synthesized, and their molecular structures and photophysical properties were investigated. In the solid state, these complexes exhibit green photoluminescence with microsecond lifetimes (λ_max = 515–538 nm; τ = 11.8–19.1 μs) at 298 K. The emission of the complexes originates from the (σ + X) → π* transition. All three complexes displayed good thermal stability.     

Synthesis,characterization and luminescent properties of copper(I) halide complexes containing biphenyl bidentate phosphine ligand

Copper(I) halide complexes having thermally activated delayed fluorescence (TADF) and phosphorescence have attracted much attention. Here, a series of four-coordinate dinuclear copper(I) halide complexes, [CuX(bpbp)]₂ (bpbp = 2,2′-bis(diphenylphosphino)biphenyl, X = I (1), Br (2) and Cl (3)), were synthesized, and their molecular structures and photophysical properties were investigated. The structural analysis reveals that two copper(I) centers are bridged by two halogen ligands to form a dinuclear structure with a four-membered Cu₂X₂ ring. These complexes exhibit yellow to blue emission in the solid state at room temperature and have peak emission wavelengths at 575–487 nm with microsecond lifetimes (τ = 6.2–19.8 μs) and low emission quantum yields (<0.01%). The emissions of 1–3 originate from MLCT, XLCT, and IL (intraligand) transitions. Three complexes displayed good thermal stability.     

Synthesis,characterization, and luminescent properties of three-coordinate copper(I) halide complexes containing a carbazolyl monodentate phosphine ligand

Abstract

A series of three-coordinate dinuclear copper halide complexes containing acarbazolyl monodentate phosphine ligand, [CuX(dppc)]₂ (dppc =3,6-di-tert-butyl-9-[2-(diphenylphosphino)phenyl]carbazole, X?=?I (1), Br (2), and Cl (3)), were synthesized, and their molecular structures and photophysical properties were investigated. The structural analysis reveals that two copper(I) centers are bridged by two halogen ligands to form a dinuclear structure with a four-membered Cu₂X₂ ring. Crystal structures of 1-3 contain 1-D supramolecular arrays constructed by intermolecular C–H···π interactions. These complexes exhibit blue to green emission in the solid state at room temperature and have peak emission wavelengths at 492–495?nm with microsecond lifetimes and low emission quantum yields (< 0.01%). The emission of 1-3 mainly originates from MLCT, XLCT, and IL (intraligand) transitions. The three complexes displayed good thermal stability.     

Syntheses,crystal structures and photophysical properties of d10 transition-metal (Ag+, Cu+, Cd2+ and Zn2+) coordination complexes based on a thiophene-containing heterocyclic thioamide

Four d¹⁰ transition-metal coordination complexes 1–4 (1: [Ag₂(TPT)₂(TPTH)₂]; 2: [Cu₆(TPT)₆]·2DMF; 3: [Cd(TPT)₂(TPTH)]·CH₃CH₂OH, 4: [Zn(TPT)₂]_n) have been constructed from a newly designed heterocyclic thioamide ligand, TPTH (TPTH = 4-(thiophen-2-yl)-pyrimidine-2-thiol). All complexes have been structurally elucidated by single crystal X-ray diffraction analyses. Except for 4, which shows a one-dimensional (1-D) chain structure, 1–3 are all discrete coordination complexes featuring dinuclear, hexanuclear and mononuclear entities, respectively. Their photophysical properties have been evaluated in the solid state at room temperature by UV–vis diffuse reflectance and luminescence spectra. Among them, 2 exhibits a strong red luminescence (λ_em = 699 nm) with a remarkable red-shift of the maximum emission compared to that of the TPTH ligand (λ_em = 536 nm). The red emission observed with 2 is ascribed to a LMCT (ligand-to-metal charge transfer) transition which agrees with the DFT calculations.     

Synthesis,characterization and DNA binding investigations on 1D polymeric copper(II) complexes of 1-amidino-O-alkylurea (alkyl = methyl,ethyl or propyl) having both dicyanamido and chloro bridges

Three new copper(II) complexes, [(CuL)₂Cl{N(CN)₂}₃]_n, where L = 1-amidino-O-methylurea (1), 1-amidino-O-ethylurea (2), or 1-amidino-O-propylurea (3), have been synthesized and characterized. The single crystal X-ray structure of 2 and X-ray powder diffraction analysis on 1 and 3 show that they crystallize in the monoclinic system. The neutral dinuclear entity of 2 contains a crystallographic 2-fold axis passing through the amido nitrogen of a bridging dicyanamido ligand. The dinuclear units are bridged by weak Cu … Cl interactions through the axial position of both copper ions to form a 1D polymer. The interaction of 1–3 with calf-thymus DNA (CT-DNA) has been explored by using absorption, emission, thermal denaturation, cyclic voltammetric studies, and viscosity experiments. The complexes bind to CT-DNA by non-intercalative mode and the order of binding ability is 1 > 2 > 3.     

Dinuclear copper(I) complexes of N-methylbenzothiazole-2-thione: synthesis,structures, antibacterial activity and DNA interaction

Three copper(I) halide complexes containing N-methylbenzothiazole-2-thione (mbtt) and triphenylphosphine (PPh₃) have been prepared and structurally characterized by X-ray single-crystal analysis. Copper(I) halide precursors [CuΧ(PPh₃)]₄ (X = Cl, Br, I) react with mbtt in 1 : 4 M ratio to give complexes of formula [CuΧ(mbtt)(PPh₃)]₂. Hereby, dimerization is achieved in case of copper(I) chloride and bromide via halide bridges, while copper(I) iodide gives the binuclear thione-S-bridged dimer. The new complexes show moderate in vitro antibacterial activity against certain bacterial strains. The interaction of the compounds with calf-thymus DNA was monitored via UV–vis spectroscopy, DNA-viscosity measurements and their competition with ethidium bromide for the DNA intercalation sites studied by fluorescence emission spectroscopy. Intercalation was revealed as the probable mode of binding.     

Syntheses,crystal structures,and properties of two dinuclear iron(III) complexes constructed with 1,2,3,5-benzenetetracarboxylic acid and chelating N-donor auxiliary coligands

Two dinuclear Fe(III) metal–organic complexes with tetracarboxylate and chelating N-donor ligands, [Fe(Hbtec)(phen)(H₂O)]₂·2H₂O (1) and [Fe(Hbtec)(bpy)(H₂O)]₂·2H₂O (2) (H₄btec = 1,2,3,5-benzenetetracarboxylic acid, phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine) have been prepared and characterized by elemental analysis, IR spectroscopic, and X-ray diffraction methods. Both complexes crystallize in the monoclinic space group P2₁/c with two Fe(III) ions bridged by two Hbtec^3? ligands into a dinuclear unit. Hydrogen bonding connects the dinuclear units into a 3-D framework. The dinuclear units are 10-connected nodes that produce a 3-D framework with topology Schläfli symbol as (3¹²·4²⁸·5⁵). Thermal stabilities and luminescent properties of the two complexes have also been investigated.     

Copper(II) complexes of two TEMPO-functionalized polypyridyl ligands: structure and catalytic activity in alcohol oxidation

The reaction of copper(II) salts with Bpy-TEMPO and Tpy-TEMPO (Bpy-TEMPO = [2,2′]Bipyridinyl-5,5′-dicarboxylic acid bis-[(2,2,6,6-tetramethyl-1-oxy-piperidin-4-yl)-amide]; Tpy-TEMPO = 2,2,6,6-tetramethyl-4-(2,2′:6′,2″-terpyridin-4′-yloxy)piperidin-1-oxyl) gave dinuclear Bpy-TEMPO-Cu₂ (1) and mononuclear Tpy-TEMPO-Cu (2), respectively. The Cu(II) complexes were characterized by single crystal X-ray analysis. In 1, Cu(II) has a distorted square pyramidal coordination geometry, with a bridging chloride as the axial ligand. The Cu(II) core in 2 also exhibited a distorted square pyramidal coordination geometry, with one chloride as an axial ligand. Weak interactions such as π-interactions and hydrogen bonds are observed in both complexes. When applied as catalysts for the oxidation of benzyl alcohol to benzaldehyde in air, 1 exhibited higher activity than 2 for reactions in o-xylene at 60°C with DBU as a base. High yield (67%) of benzaldehyde was observed when using 1 as a catalyst in a solution of o-xylene with DBU at 60°C.     

Two Cd(II) coordination polymers based on tris(p-carboxylphenyl)phosphine oxide accompanied by in situ ligand formation

Two Cd(II) coordination polymers constructed from tris(p-carboxylphenyl)phosphine oxide (H₃TPO), [Cd(HTPO)(1,4-bix)·3H₂O]_n (1) and [Cd₂(HTPO)(HBPO)(H₂O)₂]_n (2) (1,4-bix = 1,4-bis(imidazol-1-ylmethyl)benzene, H₃BPO = bis(4-carboxylphenyl)phosphinic acid), were synthesized and identified by IR, elemental analysis, and single-crystal X-ray diffraction analysis. The 1,4-bix ligand leads to 1 as a ladder-like 1D chain structure. In 2, adjacent Cd₂ units are bridged by HBPO^2– and HTPO^2– ligands to form a 3D structure. The H₃BPO ligand is formed from the in situ reaction of H₃TPO. It is the first example from hydrated Cd(II) salt promoting partial hydrolysis of a phosphine oxide ligand. The thermal behavior and solid-state photoluminescence properties correlated with the corresponding structural features were investigated.     

Chromotropism studies on copper(II) compounds. Part II. Dinuclear copper(II) complexes with triply-bridged hydroxo,acetate, and halo ligands

Abstract

Two triply-bridged dinuclear copper(II) complexes of formula [LCu(μ-OH)(μ-OAc)(μ-X)CuL]X?0.5H₂O where L is a bidentate ligand of N-(pyridine-2-ylmethyl)propane-2-amine and X=Cl, 1 and Br, 2 were synthesized and characterized by elemental analyses, spectroscopic techniques (IR, UV–Vis, EPR), thermal analysis, conductance measurements, and single-crystal X-ray structure determination. The structures of both complexes are similar. The complexes show a distorted square-pyramidal arrangement around each copper(II) ion with a CuN₂O₂X chromophore in which both copper(II) ions are connected by a hydroxo bridge and a triatomic syn-syn carboxylato bridge in equatorial positions and a halide ion bridge at the axial site. The chromotropism behavior of the complexes, including solvato-, thermo-, and halochromism, were investigated in detail. Their halochromism was investigated in the pH range of 2.0–11.0 by visible absorption spectroscopy. The reversible color variations from blue to colorless are attributable to deprotonation and protonation of the ligands. The complexes show reversible thermochromism in solution due to dissociation and recombination of ligands to copper ions.     

Syntheses,steric hindrance effects,luminescent properties and TD-DFT calculations for a series of copper(I) iodide coordination complexes

A series of copper(I) coordination complexes, CuI(Phen)[2-(Dpp)bp] (1) (Phen?=?phenanthroline, 2-(Dpp)bp?=?2-(Diphenylphosphino)-biphenyl), Cu₂I₂(Phen)[2-(Dpp)bp] (2), CuI(2-PBI)[2-(Dpp)bp] (3) and (2-PBI?=?2-(pyridin-2-yl)-1H-benzo[d]imidazole) and CuI(Bipy)[2-(Dpp)bp] (Bipy?=?2,2′-bipyridine) (4) have been synthesized. X-ray crystal structure studies revealed that complexes 1, 3 and 4 showed mononuclear structures with the copper atoms coordinated by iodide, a chelating nitrogen-donor ligand, and a monodentate phosphine ligand. However, the coordination centers display different distortions of their tetrahedral geometries, according to the steric hindrance of the bulky phosphine ligands. Complex 2 has a dinuclear structure, with trigonal and tetrahedral coordination centers. Variations in the aromatic system of the N-heterocyclic ligands result in different luminescence properties. Thus, the emission maxima for these complexes range from 580 to 642 nm, with lifetimes of τ?=?0.6–0.9 and 1.6–4.2 μs. TD-DFT calculations reveal the origin of the luminescence to be metal–ligand charge transfer, as well as halogen–ligand charge transfer. The optical absorption spectra and thermal stabilities of the complexes have also been studied.     

配体尺度对配合物结构及光催化降解活性的调节:从零维到一维的Cu(Ⅱ)配合物

合成了桥联吡啶类配体2,6-二(3′-吡啶乙炔基)-4-甲基苯胺(L1)和未见文献报道的尺度更短的桥联吡啶配体2,6-二(3′-吡啶基)-4-甲基苯胺(L2),在常温下分别将其与一水合醋酸铜(Cu(OAc)2·H2O,OAc-=CH3CO2-)进行配位反应获得零维的配位大环分子[Cu2(L1)(OAc)4]2(1)和一维的配位聚合物{[Cu2(L2)(OAc)4]·2CH2Cl2·CH3CN}n(2)。对获得的2个配合物进行了X射线单晶衍射、傅里叶红外光谱、元素分析等方面的结构表征。对比其结构可以发现,配合物1和2中均存在{Cu2(OAc)4}的二核铜簇,不同的是2个配合物中配体的配位取向不同:配位大环化合物1中的配体L1以U型构型与二核铜簇形成了“2+2”的平面配位大环结构,而化合物2中的配体L2则以Z型构型连接相邻的二核铜簇形成一维链状结构。2个化合物的结构差异是由于配体的尺度导致的,更短的尺度使得配位氮原子取向发生改变而产生不同的配位构型,这显示了结构调控中配体尺度的影响作用。通过测定配体与配合物在固态下的荧光发射性质,证实了铜的引入会猝灭配体自身的荧光发射;同时,采用亚甲基蓝(MB)为底物的光催化降解实验证明,大环配位分子的光催化降解活性明显优于一维配位聚合物,两者的催化活性均远远强于醋酸铜本身的催化活性。     

Copper(I)-1,1,1-tris(diphenylphosphinomethyl)ethane complexes with different coordination modes tuned by auxiliary ligands and their spectroscopic properties

Three mono-, bi- and tetranuclear copper(I) complexes, [Cu(phen)(triphos-O)]BF₄ (1) (phen = 1,10-phenanthroline, triphos = 1,1,1-tris(diphenylphosphinomethyl)ethane), [Cu₂(bipy)(triphos)₂](BF₄)₂ (2) (bipy = 4,4′-bipyridine), and [Cu₄(MeOC^N^N)₄(triphos)₂(bipy)](BF₄)₄ (3) (MeOC^N^N = 6-(4-methoxyphenyl)-2,2′-bipyridine), have been synthesized and characterized by NMR spectroscopy, electrospray ionization, and matrix-assisted laser desorption ionization time-of-flight mass spectrometries, elemental analysis, and X-ray crystal analysis. The crystal structure investigation revealed the copper ions of the complexes have pseudo-tetrahedral coordination geometry. The electronic absorption spectra of 1, 2, and 3 contain low-energy bands at 350–500 and 400–650 nm, which are assigned to d(Cu) → π*(phen or bipy) and a mixture of d(Cu) → π*(MeOC^N^N) and d(Cu) → π*(bipy) transitions, respectively. Complex 2 displays a strong, long-lived solid-state emission with a maximum at 555 nm and lifetime of 13.6 μs at room temperature. Photoinduced electron-transfer properties of 2 and 3 involving nanosecond time-resolved absorption spectroscopy and electron spin resonance techniques were studied.     

Synthesis,Crystal Structure,and Properties of a Dinuclear Cu(I) Cluster

Abstract

A new dinuclear copper(I) cluster complex, [(o-Tol)₃PCuI₂CuP(o-Tol)₃(DMF)] (1) ((o-Tol)₃P = tris(2- methylphenyl)phosphine, DMF = N, N′-dimethylformamide), has been synthesized and the crystal structure was determined by a single-crystal X-ray diffraction study. The dinuclear copper(I) cluster molecule containing an asymmetric Cu₂I₂P₂O core and the dinuclear clusters are fused together by a strong π–π stacking interaction to form asupramolecular one-dimensional (1D) chain. After having compared the relevant complexes composed of CuI and monodentate triarylphosphine ligands, the impact of the substituent of the triarylphosphine ligand to the subsequent complex structure has also been discussed.Except for a strong π–π* bond, the complex 1 also exhibits a weak metal-to-ligand charge transfer (MLCT) absorption bond in the 430–530-nm region and displays a weak green-yellow emission when irradiated by ultraviolet (UV) light. The thermogravimetric analysis demonstrates that its thermal stability is good, and the corresponding PXRD analysis has revealed that the final, organic-free decomposed product is CuI.     

Tricarbonylrhenium(I) complexes with the N,6-dimethylpyridine-2-carbothioamide ligand: combined experimental and calculation studies

Abstract

A new series of tricarbonyl complexes of rhenium(I) in the “2 + 1” system with the bidentate ligand N,6-dimethylpyridine-2-carbothioamide ((CH₃)NC₅H₄-CS-NH-CH₃, MeLH(Me)_NS) and a monodentate ligand (halides Cl, Br, or I, and the pseudohalide NCS anion) was synthesized. The use of mixed ligands led to the formation of neutral tricarbonylrhenium(I) complexes [Re(CO)₃(MeLH(Me)_NS)X] (X = Cl, Br, I, NCS) (1–4). Single-crystal X-ray diffraction was used to determine the crystal structures of all four compounds and those results were compared with molecular structures obtained from DFT calculations using the PBE0/def2-TZVPD approach. The complexes were also characterized by spectroscopic (FT-IR, NMR, and UV–vis) and analytical (HPLC, TGA, EA, ESI-MS) techniques. IR and UV–vis spectra were also calculated by DFT and TD-DFT methods. The cytotoxicity of these complexes was estimated using human ovarian cancer cell lines (A2780 and A2780cis), cervical cancer cells (HeLa), and non-cancerous human embryonic kidney cells (Hek-293). The toxicity of most complexes was moderate or low toward cancer cell lines (IC₅₀ = 46–231 μM) and similar against non-cancerous cells (IC₅₀ = 41-121 μM). Only the complex with chlorido ligand remarkably inhibited growth of ovarian cancer cells (IC₅₀ = 3 and 12 μM for A2780 and A2780cis, respectively). The cytotoxicity of 1 was higher than that of cisplatin.     

Syntheses,crystal structures,and Jack bean urease inhibitory activities of copper(II) complexes derived from 4-tert-butyl-N′-(1-(pyridin-2-yl)ethylidene)benzohydrazide

Two new copper(II) complexes, [CuL(HL)]·ClO₄ (1) and [Cu₂Br₂L₂]·0.85H₂O (2), where L is the monoanionic form of 4-tert-butyl-N′-(1-(pyridin-2-yl)ethylidene)benzohydrazide (HL), have been prepared. The complexes were characterized by infrared and UV–vis spectra, and single crystal X-ray diffraction. Complex 1 is a mononuclear copper(II) species and 2 is a bromido-bridged dinuclear copper(II) species. The Cu ion in 1 is in an octahedral coordination mode and that in 2 is trigonal-bipyramidal. The Jack bean urease inhibitory assay indicated that 2 is active, with IC₅₀ value of 20.6 ± 2.3 μmol L^?1, while 1 is inactive. Molecular docking of 2 with Jack bean urease was studied.     

Synthesis and Characterizations of Strongly Phosphorescent Copper(I) Halide Complexes with Bridged Bis[2-(diphenylphosphino)phenyl]ether Ligand

A series of strongly phosphorescent copper(I) halide complexes, namely [Cu(μ-X)POP]₂ (X = Cl (1), Br (2), I (3), Br_0.5Cl_0.5 (4), POP = bis[2-(diphenylphosphino)phenyl]ether), have been synthesized by reacting CuX with the diphosphine ligand in 1:1 molar ratio. All complexes were characterized by spectroscopic analysis (IR, UV–Vis), elemental analysis, and photoluminescence study. Single-crystal X-ray diffraction revealed that complex 2 is a dinuclear structure which is constructed by two μ-X bridges and two POP ligands as μ₂ bridges. Other complexes were determined as isologues of complex 2 by powder X-ray diffraction and elemental analysis. All complexes exhibit intense blue-green phosphorescence with a lifetime of ~1 μs in the solid state. The halogen-mixed complex presents a lightly change in the luminescence comparing to that of parent complexes. The excited states of all complexes have been assigned as halide-to-ligand charge transfer state mixed metal-to-ligand charge transfer character based on the time-dependent density functional theory calculations. All complexes are thermally stable according to thermogravimetric analysis so that they are suitable for applying in luminescent devices.     

Four-coordinate N-heterocyclic carbene (NHC) copper(I) complexes with brightly luminescence properties

Three four-coordinate N-heterocyclic carbene (NHC) copper(I) complexes, [Cu(Py-Im)(POP)](PF₆) (P1), [Cu(Py-BenIm)(POP)](PF₆) (P2), and [Cu(Py-c-BenIm)(POP)](PF₆) (P3) (Py-Im = 3-methyl-1-(pyridin-2-yl)-1H-imidazolylidene, Py-BenIm = 3-methyl-1-(pyridin-2-yl)-1H-benzo[d]imidazolylidene, Py-c-BenIm = 3-methyl-1-(pyridin-2-ylmethyl)-1H-benzo[d]imidazolylidene, POP = bis([2-diphenylphosphino]-phenyl)ether), have been synthesized without transmetalation of the NHC–Ag(I) complex for the first time. The photophysical properties of the resultant NHC–Cu(I) complexes have been systematically investigated via spectroscopic methods. All complexes exhibit good photoluminescence properties with long excited-state lifetimes and moderate quantum yields. Density functional theory and time dependent density functional theory calculations were employed to rationalize the photophysical properties of the NHC–Cu(I) complexes.     

New polynuclear compounds based on N-benzyliminodipropionic acid: solution studies,synthesis, and X-ray crystal structures

Three new polynuclear compounds based on a dicarboxylic acid ligand are reported. In particular, two Cu(II) coordination compounds, [Cu₂(H₂O)₆(Hbzlidp)₂](CF₃SO₃)₂·2H₂O (1) and [Cu(NO₃)(Hbzlidp)]_∞ (2) (bzlidp^2? = N-benzyliminodipropionate anion), and a Ni(II) dinuclear compound, [Ni₂(H₂O)₄(bzlidp)₂] (3), were synthesized and characterized by IR spectroscopy, elemental analysis and single crystal X-ray diffraction. Different structures were obtained depending on the reaction conditions. The structural analyses reveal that 1 was formed by dinuclear [Cu₂(H₂O)₆(Hbzlidp)₂]²⁺ units built by two copper(II) ions joined through two Hbzlidp^? ligands, while 2 was formed by pairs of Cu(II) centers bridged by four syn,syn carboxylate groups to generate “paddle wheel” units. The dinuclear copper units are arranged in a rhombus type grid, in a 2-D layer structure. In both cases, the N was protonated and not coordinated to the metal center. Compound 3 was formed by [Ni₂(H₂O)₄(bzlidp)₂] neutral dinuclear units, with octahedral Ni(II) centers. Solution studies of the ligand–M(II) systems (M(II) = Mn, Co, Ni, Cu, Zn, Cd, and Pb) were also carried out.     

Copper(II) complexes of picolinamide incorporating both tricyanomethanido and 2-(aminomethyl)pyridine moieties

Reaction of picolinamide (pca) with potassium tricyanomethanide (tcm) and copper(II) perchlorate in 1-propanol gave [Cu(pca)₂(tcm)₂] (1a and 1b) while addition of 2-(aminomethyl)pyridine (2-ampy) provided [Cu(pca)(2-ampy)(tcm)](ClO₄) (2). These compounds have been characterized by IR, powder X-ray diffraction, single crystal X-ray diffraction, combustion analysis, and temperature-dependent magnetic susceptibility. Compound 1a crystallized in the monoclinic space group C2/c whereas 1b and 2 crystallized in the triclinic space group Pī. In 1a, the copper complexes stack alternately with semi-coordinated tcm ions creating layers, further stabilized by hydrogen bonding to neighboring layers. In 1b, the tcm ions are coordinated to complete the octahedral coordination sphere around the copper ions and form staggered layers parallel to the ab face diagonal. In 2, stacks of copper complexes form bilayers, held together by hydrogen bonding between tcm ions and amino groups, parallel to the a axis. Variable temperature magnetic susceptibility data were collected on 1 and 2 from 1.8–310 K. The data were fit to the Curie–Weiss law which showed no significant magnetic exchange as expected based upon the crystal structures [1 ? Curie constant = 0.419(2) emu-K/mol-Oe, θ = ?0.10(6)°; 2 – Curie constant = 0.438(1) emu-K/mol-Oe, θ = 0.05(3)°].