DUAL BEHAVIOR OF ACETONITRILE IN A NEW CADMIUM CYANIDE CLATHRATE: CRYSTAL STRUCTURE OF Cd(CH3CN)2Cd(CN)4·2CH3CN

Abstract

We report a new crystal structure of the title clathrate containing tetrahedral and octahedral Cd atoms in a ratio of 1:1. The preparation of the compound is similar to that of the cristobalite-like clathrate Cd(CN)₂·G, where all Cd atoms are tetrahedral. The new inclusion compound crystallizes in the monoclinic space group C2/c, a = 12.337(4), b = 11.964(3), c = 13.594(3) Å, β = 108.60(2)°, Z = 4, R = 0.034 for 1631 reflections. The three-dimensional host framework is built of alternate linkages between the tetrahedral Cd atom of the tetracyanocadmate and the octahedral Cd atom similar to that of the Hofmann-Td and the en-Td types. In the new clathrate dual behavior of acetonitrile, one as a unidentate ligand in the three-dimensional host framework and the other as the guest in the cage-like cavity, has been demonstrated.     

Synthesis and Crystal Structure of an Azido-Bridged Cadmium(II) Dimer [L2Cd2(μ-N3)2(N3)2] (L=1,4,7-Triazacyclononane)

A new dinuclear Cd(II) complex, [L₂Cd₂(μ-N₃)₂(N₃)₂], containing two end-on bridging azide ligands, two monodentate N₃ ligands and 1,4,7-triazacyclononane as the capping ligand, has been synthesized and its structure determined by X-ray crystallography. The complex crystallizes in the monoclinic space group P2₁/c with a=8.467(3), b=14.359(5), c=10.115(4)Å, β=95.026(6)° and z=4. The cadmium(II) centre is six-coordinate with distorted octahedral geometry, bonded to three N atoms of the 1,4,7-triazacyclononane, two nitrogen atoms of μ-azide bridges and one nitrogen atom of a monodentate azide ligand. Neighboring Cd(II) atoms are linked by the double end-on azide bridges.     

SYNTHESIS,CRYSTAL STRUCTURE AND MAGNETIC PROPERTIES OF A MANGANESE(III) COMPLEX WITH SALICYLATE AND IMIDAZOLE LIGANDS

Abstract

A new manganese(III) complex [HimH][Mn(sal)₂(imH)₂]CH₃OH (sal = salicylate, C₇H₄O₃ ^2-; imH = imidazole, C₃H₄N₂; [HimH]⁺ = imidazole cation (C₃H₅N₂) has been prepared and characterized by X-ray analysis and magnetic measurements. The compound crystallizes in the monoclinic space group P2 ₁ with a = 9.931(2), b = 10.237(1), c = 12.926(7) Å, β = 102.740° and Z = 2. The structure has been refined to R = 0.030 and R_w = 0.031. The Mn(III) ion has elongated octahedral coordination with mutually trans imidazoles occupying axial sites. The equatorial plane is defined by four O atoms of two salicylates. Each [HimH]⁺ cation (imidazolium) is associated with two complex anions through hydrogen bonds as an imidazolium bridge. The variable temperature magnetic susceptibility for the complex in the temperature range 77-300 K has been interpreted in terms of a single-ion zero-field splitting model with a molecular field term correction. The values obtained for D, g. and zj' are -6.93 cm^?1, 2.00 and -0.90 cm^?1.     

A structure and magnetic properties of one-dimensional manganese/cobalt coordination polymers with 5-nitro-1,3-benzenedicarboxylic acid and imidazole

One-dimensional manganese(II) complex, [Mn₂(5-nbdc)₂(imH)₆] · 2H₂O (1) (5-nbdcH₂ = 5-nitro-1,3-benzenedicarboxylic acid and imH = imidazole), has been hydrothermally synthesized and structurally characterized by X-ray crystallography with the following data: orthorhombic, space group Pna2(1), M _r = 972.63 for Mn₂C₃₄H₃₄N₁₄O₁₄, a = 13.3391(12) Å, b = 16.4657(15) Å, c = 18.2177(16) Å; V = 4001.3(6) ų, Z = 4, D _calcd 1.615 g cm^?3, µ = 0.718 mm^?1, the final R = 0.0490 and wR = 0.1277 for 7278 observed reflections (I > 2σ(I)). Complex 1 exhibits very weak intra-chain ferromagnetic coupling (J k^?1 = 0.001 K) with g = 1.930. The magnetism of a one-dimensional cobalt(II) complex [Co(5-nbdc)₂(imH)₂] _n (2) indicates weak intra-chain anti-ferromagnetic coupling (J k^?1 = ?0.067 K) with g = 2.0791.     

Structural diversity in pseudohalide complexes of cadmium(II) with N-methylthiourea (Metu): Polymeric [Cd(Metu)2(NCS)2]n versus monomeric [Cd(Metu)2(CN)2]

Cadmium(II) complexes, catena-poly[bis(thiocyanato-κN)bis(N-methylthiourea)cadmium(II)], [Cd(Metu)₂(NCS)₂]_n (1) and dicyanidobis(N-methylthiourea)cadmium(II), [Cd(Metu)₂(CN)₂] (2) were prepared and their structures were determined by single crystal X-ray analysis. In 1, the cadmium(II) ion is bound to four sulfur atoms of bridging Metu ligands and two nitrogen atoms of thiocyanate adopting a distorted octahedral environment. In 2, the geometry around cadmium is distorted tetrahedral attained by two cyanide ions and two methylthiourea molecules bound through the sulfur atoms. The crystal structures of both complexes show intra and intermolecular hydrogen bonding interactions. The complexes were also characterized by IR and NMR spectroscopy and the spectroscopic data were discussed in terms of the nature of bonding.     

[Cu(X-salicylato)2(N,N-diethylnicotinamide)2(H2O)2] complexes: conformational polymorphism and its consequence in supramolecular hydrogen-bonding networks formation

Novel copper(II) X-salicylate complexes with N,N-diethylnicotinamide (dena) of the formula [Cu(RCOO)₂(dena)₂(H₂O)₂] (RCOO = 3-methylsalicylate anion (3-Mesal, 1), 4-methylsalicylate anion (4-Mesal, 2), 5-methylsalicylate anion (5-Mesal, 3), 5-methoxysalicylate anion (5-MeOsal, 4) or 4-methoxysalicylate anion (4-MeOsal, 5)), and complex [Cu(3-MeOsal)₂(dena)₂(H₂O)₂]∙2H₂O (3-MeOsal = 3-methoxysalicylate anion (6)) have been prepared in the crystalline forms and characterized by spectroscopic methods (IR, Vis–UV, EPR). All the compounds according to their composition (1–5) seem to possess octahedral copper(II) stereochemistry. The complex 1 has been prepared in two different forms. X-ray analyses of the complexes 1, 4, and 5 were carried out and they featured a tetragonal-bipyramidal geometry around the copper atoms. The tetragonal planes are created by X-salicylate anions bonded to the copper(II) atoms via unidentate carboxylate oxygen atoms and the pyridine ring nitrogen atoms of the neutral ligand N,N-diethylnicotinamide, while in axial positions are water molecules. The two forms of complex 1 present conformation polymorphs and supramolecular isomers.     

Synthesis,characterization, spectroscopic,and thermal studies of imidazole complexes of metal benzenesulfonates. Crystal structure of [M(imH)<Subscript>3</Subscript>(H<Subscript>2</Subscript>O)<Subscript>3</Subscript>]·(BS)<Subscript>2</Subscript> [M=Ni(II) and Co(II)]

Four novel transition metal benzenesulfonate (BS) complexes of imidazole (im) with a general formula [M(imH)₃(H₂O)₃]·(BS)₂ [M=Mn(II) (1), Ni(II) (2), Co(II) (3)] and [Cu(BS)(imH)₃]·(BS) (4) have been synthesized and characterized by physicochemical and spectroscopic methods. The complexes 2 and 3 have also been characterized by single X-ray diffraction technique. The BS anion in complexes 1–3 acts as a counter anion, while in complex 4, it acts as both ligand and counter anion. The Ni and Co complexes are isomorphous, crystallizing in the monoclinic crystal system with C2/c space group. Each metal(II) atom in 2 and 3 is octahedrally coordinated by three imidazole and three aqua ligands, adopting a mer-coordination mode with Ni(II) or Co(II) centers. In both 2 and 3, the H2C atom has bifurcated donor (O3 and O5) atoms, forming a bifurcated hydrogen bond. This hydrogen bond links the complex cation and BS anion, forming one-dimensional hydrogen-bonded supramolecular chains. The complexes exhibit different decomposition characteristics. Magnetic susceptibility measurement shows that complex 3 has orbital interactions.     

Preparation,Structure and Thermal Decomposition of Cu(II) Complexes with 2-Chloro- and 2,3-Dichlorobenzoic Acids and Imidazole

The reaction products of Cu(II) 2-chlorobenzoate and imidazole (1), and of Cu(II) 2,3-dichlorobenzoate and imidazole (2) formulated as CuL'₂·3imd and CuL"·3imd (L' = C₇H₄ClO₂, L" = C₇H₄Cl₂O₂ ^?, imd = imidazole), were prepared and characterized by means of structural and spectroscopic measurements and thermochemical properties. The blue (1) and green (2) compounds crystallize in the monoclinic system with space group C2/c, cell parameters a = 20.753(4), b = 8.414(2), c = 14.429(3) Å, β = 90.15(3)°, V = 2519.5(9) &Aringsup3;, Z = 4 for (1) and a = 21.335(4), b = 8.417(2), c = 15.030(3) Å, β = 94.11(3)°, V = 2692.1(10) &Aringsup3;, Z = 4 for (2). The complexes decompose at 483 K.     

Syntheses,crystal structures and properties of two cadmium coordination polymers containing bis (2-methylimidazol-1-yl)methane(2-mBIM) and bis (imidazol-1-yl)methane (BIM) ligands

Coordination polymers, {[Cd(2-mBIM)₃](ClO₄)₂} _n (1) and [Cd(BIM)₂(NO₃)₂] _n (2), have been prepared from the reaction of bis(2-methylimidazol-1-yl)methane(2-mBIM) with Cd(ClO₄)₂ and bis(imidazol-1-yl)methane (BIM) with Cd(NO₃)₂ in ethanol and water, respectively. Their structures were characterized by single crystal X-ray diffraction and IR spectroscopy. Compound 1 crystallizes in the rhombohedral space group R-3c with a = b = 12.3617(5) Å, c = 38.896(3) Å, γ = 120°, V = 5147.5(5) ų, z = 6. The Cd^II occupies a crystallographic inversion center and is coordinated by six N atoms from six distinct 2-mBIM ligands to form a slightly distorted octahedral geometry. Each 2-mBIM is coordinated to two Cd^II cations, linking alternatively four Cd^II cations, resulting in a 32-membered M₄L₄ macrometallacycle. Compound 2 crystallizes in the monoclinic space group C2/m with a = 14.400(3) Å, b = 9.3894(18) Å, c = 8.6926(17) Å, β = 123.499(2)°, V = 980.1(3) ų, z = 2. The Cd coordinates to four nitrogen atoms from four different BIM and two nitrates to form a slightly distorted octahedral geometry. The BIM ligands bridge to form a 1-D infinite double-bridged chain structure with 16-membered M₂L₂ macrometallacyclic structural units.     

STRUCTURE OF A POLYMERIC BENZENETETRACARBOXYLATO COMPLEX OF Mn(II) WITH IMIDAZOLE

Abstract

A novel polymeric μ-BTC complex of Mn(II) with imidazole has been synthesized, where BTC is the 1,2,4,5-benzenetetracarboxylato tetravalent anion, and its crystal structure has been determined by X-ray diffraction methods. The complex crystallizes in the monoclinic spacegroup P2₁/n with a = 11.184(5), b = 9.177(2), c = 18.243(1)Å and β = 107.84(1)°. Each BTC ligand, located around the crystallographic inversion centre, bridges four Mn(II) atoms through four carboxyl groups to form a three dimensional polymeric structure. The carboxyl groups in the ortho-position of BTC bridges Mn(II) atoms related by the crystallographic screw axis to form helical complex chains along the b axis. Coordination around the Mn(II) atom is distorted octahedral; two BTC anions coordinate to Mn(II), one in unidentate fashion and the other as a chelate. The coordination distance of the unidentate ligand is much shorter than in the chelated ligand.     

Novel ternary cobalt(II) and nickel(II) complexes of N-phthaloylglycinate. Synthesis, characterization and X-ray crystal structure

A new series of N-phthaloylglycineate (N-phthgly) ternary complexes of cobalt(II) and nickel(II) with imidazole (imi), N-methylimidazole (mimi) and 2,2′-bipyridyl (bipy) have been synthesized and characterized by elementary analyses, IR spectroscopy, thermogravimetric analysis. X-ray crystal structure analyses of the three complexes of [Co(mimi)₂(N-phthgly)₂] (1), [Co(bipy)(OH₂)₄](N-phthgly)₂ (2) and [Ni(imi)₂(N-phthgly)₂(OHCH₃)₂] (3) were also carried out. In complex (1), the Co(II) exists in a distorted tetrahedral enviroment, where two nitrogen atoms of two methylimidazole molecules and two oxygen atoms of the carboxylate group of two N-phthaloylglycinate molecules are coordinated. On the other hand, in complex (2) the cobalt atom coordinates a 2,2′-bipyridine molecule and four water oxygen atoms forming a distorted octahedral conformation. A molecule of N-phthaloylglycinate is connected by van der waals contact and H-bonds. For complex (3), the nickel atom is surrounded by four oxygens (two oxygens of two different N-phthaloylglycinate molecules and two of methanol ligand) in the basal plane of octahedron along with two imidazole nitrogen atoms at the apical positions. Strong intramolecular H-bond exists between the uncoordinated carboxylic oxygen of the N-phthaloylglycinate ligand and the O–H of the methanol group.     

Novel trinuclear copper(II) complexes with α,β-unsaturated carboxylates and imidazole

A MeOH solution of imidazole reacts with Cu₂A₄(H₂O)₂ [A = CH₂=CHCO^– ₂, CH₂=C(Me)CO^– ₂] to yield novel trinuclear copper(II) carboxylate complexes of general formula: Cu₃A₅(OH)(imH)₃ [(1) A=CH₂=CHCO^– ₂; (2) A = CH₂=C(Me)CO^– ₂; imH = imidazole]. The crystal structure of (2) has been determined. The geometry of one copper(II) atom is distorted trigonal bipyramidal, and the other two copper(II) atoms are distorted square-planar. The i.r. spectra show the presence of the absorption bands of both bidentate ₂-O,O and monodentate carboxylate ligands. The electronic reflectance spectra in the solid state suggest that the d–d transitions of complexes are in a trigonal bipyramidal ligand field and a square-planar ligand field. Room temperature X-band e.s.r. spectra of powdered samples with g _av = 2.140 for (1) and g _av = 2.092 for (2), indicate that there is no spin coupling between the copper(II) atoms.     

Syntheses and structural characterization of cadmium complexes constructed from a tetrakis(3-pyridylmethyl) functionalized ligand

A functionalized ligand (L?=?1,4,8,11-tetrakis(3-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane) was synthesized by the reaction of 1,4,8,11-tetraazacyclotetradecane (cyclam, L¹) with 3-(chloromethyl)pyridine hydrochloride. Hydrothermal reactions between L and two Cd(II) salts (nitrate or chloride) led to the formation of [CdCl₂(µ₄-4(pyridyl)L)] _n (1) and [Cd(µ-ONO₂)₂(µ₄-4(pyridyl)L)] _n (2), which were characterized by elemental analysis and single-crystal X-ray diffraction. In 1, Cd is six-coordinate, with a CdN₄Cl₂ octahedral coordination environment forming two metallamacrocycles with the functionalized cyclam. In the structure of 2, the metal possesses a distorted CdN₄O₂ octahedral coordination geometry, also presenting two metallamacrocycles. In both structures, the ligand does not chelate, but forms extended polymeric structures.     

A new one‐dimensional CdII coordination polymer incorporating 2,2′‐(1,2‐phenylene)bis(1H‐imidazole‐4,5‐dicarboxylate)

Imidazole‐4,5‐dicarboxylic acid (H₃IDC) and its derivatives are widely used in the preparation of new coordination polymers owing to their versatile bridging coordination modes and potential hydrogen‐bonding donors and acceptors. A new one‐dimensional coordination polymer, namely catena‐poly[[diaquacadmium(II)]‐μ₃‐2,2′‐(1,2‐phenylene)bis(1H‐imidazole‐4,5‐dicarboxylato)], [Cd(C₁₆H₆N₄O₈)_0.5(H₂O)₂]_n or [Cd(H₂Phbidc)_1/2(H₂O)₂]_n, has been synthesized by the reaction of Cd(OAc)₂·2H₂O (OAc is acetate) with 2,2′‐(1,2‐phenylene)bis(1H‐imidazole‐4,5‐dicarboxylic acid) (H₆Phbidc) under solvothermal conditions. In the polymer, one type of Cd ion (Cd1) is six‐coordinated by two N atoms and two O atoms from one H₂Phbidc⁴⁻ ligand and by two O atoms from two water molecules, forming a significantly distorted octahedral CdN₂O₄ coordination geometry. In contrast, the other type of Cd ion (Cd2) is six‐coordinated by two N atoms and two O atoms from two symmetry‐related H₂Phbidc⁴⁻ ligands and by two O atoms from two symmetry‐related water molecules, leading to a more regular octahedral coordination geometry. The Cd1 and Cd2 ions are linked by H₂Phbidc⁴⁻ ligands into a one‐dimensional chain which runs parallel to the b axis. In the crystal, the one‐dimensional chains are connected through hydrogen bonds, generating a two‐dimensional layered structure parallel to the ab plane. Adjacent layers are further linked by hydrogen bonds, forming a three‐dimensional structure in the solid state.     

Synthesis,Crystal Structure and Magnetic Property of Copper(II) Complex with 4′-Cyanobenzyl-1-imidazol

A neutral mononuclear complex [Cu(cbIm)₄(NO₃)₂] (cbIm = 4'-cyanobenzyl-1-imidazol) was synthesized and characterized by x-ray crystallography. It crystallizes in the triclinic space group P-1 with a = 8.249(2), b = 8.735(2), c = 16.597(2) Å, f = 81.980(10), g = 88.540(10), n = 63.570(10)° and Z = 2. The final refinement of the structure leads to R and Rw of 0.0394 and 0.0991, respectively. The crystal structure of the complex indicates a distorted octahedral environment around the Cu(II) atom, coordinated by four imidazole N atoms of four cbIm and two O atoms of two nitrates. Magnetic measurements show that the complex exhibits Curie behavior.     

Synthesis and structural characterization of two dimensional cadmium(II) coordination polymers

Reactions of Cd(NO₃)₂?·?4H₂O with NH₄SCN, ppz (ppz?=?piperazine) and bpa (bpa?=?bis(4-pyridyl)ethane) in CH₃OH afforded the cavity-containing rectangular grids {Cd(SCN)₂(ppz)} _n (1) and {Cd(NCS)₂(bpa)} _n (2). The ppz ligand in 1 is coordinated to the metal through both nitrogen atoms to form the 1-D zig-zag chain structure and distorted {CdN₄S₂} octahedral coordination geometry at each Cd center is completed by pairs of bidentate thiocyanato ligands. Complex 2 has the 2-D arrangement constructed through 1-D double μ(N,S) end-to-end bridging thiocyanato groups bridging Cd(II) chains interconnected through disordered bpa ligands.     

Syntheses,structures, and properties of two binuclear cadmium(II) iodides containing a bis(tridentate) Schiff base/tetradentate tripodal amine: control of coordination numbers by varying ligand matrices

Two binuclear cadmium(II) iodide compounds of the types [Cd₂(L1)(I)₄] (1) and [(L2)Cd(μ-I)CdI₃] (2) [L1 = N,N′-(bis(pyridine-2-yl)formylidene)triethylenetetramine and L2 = tris(2-aminoethyl)amine] are synthesized and characterized. X-ray structural study shows that each cadmium(II) in 1 has a distorted square pyramidal geometry with a CdN₃I₂ chromophore and that L1 behaves as a binucleating bis(tridentate) ligand bridging the metal centers with iodides remaining as terminals. In 2, one cadmium(II) adopts a distorted tetrahedral geometry with a CdI₄ chromophore surrounded by four iodides, while the other has a distorted trigonal bipyramidal environment with CdN₄I chromophore bound by four N atoms of L2 and one bridging iodide. Weak C–H···π interactions in 1 result in an infinite 1D chain; however, such weak non-covalent interactions are absent in 2. The Schiff base complex, 1, shows high-energy intraligand ¹(π–π*) fluorescence in DMF solution at room temperature, whereas compound 2 containing tripodal amine is fluorescent-inactive.     

Di­iodo­bis(1‐methyl‐1,3‐imidazolium‐2‐thiol­ato‐S)­mercury(II)

The reaction of 1‐methyl‐1,3‐imidazole‐2‐thione (meimtH) with mercury(II) iodide in methanol in a 2:1 molar ratio resulted in the formation of single crystals of the title compound, [HgI₂(C₄H₆N₂S)₂]. The Hg atom is coordinated by two I [2.7809 (9) and 2.7999 (8) Å] and two thione S atoms [2.520 (3) and 2.576 (3) Å] with irregular tetrahedral coordination geometry. The NH groups of the imidazole ring take part in intra‐ and intermolecular hydrogen bonds with I atoms [N?I 3.596 (8) and 3.611 (9) Å, respectively] joining mol­ecules into infinite chains parallel to the z axis.     

Nickel(II) complexes of tridentate anthracene based Schiff bases: syntheses,properties and crystal structures

The crystal and molecular structures of Ni(II) complexes with two tridentate anthracene-containing Schiff bases are reported. The Schiff bases were prepared by condensation of 9-anthraldehyde with diethylenetriamine (adien) and with dipropylenetriamine (adipn). Complexes synthesized from Ni(O₂CCH₃)₂·4H₂O and the ligands (1?:?1 mol ratio) crystallize from methanol as [Ni(adien)(O₂CCH₃)₂(H₂O)] (1) and [Ni(adipn)(O₂CCH₃)₂]·2CH₃OH (2·2CH₃OH) in space groups P2₁/n and P2₁2₁2₁, respectively. In 1, the distorted octahedral N₃O₃ coordination sphere around the metal ion is formed by the meridional N₃-donor adien, two mutually trans unidentate acetates and one water molecule. The N₃O₃ coordination sphere constituted by the N₃-donor adipn, one unidentate acetate and one bidentate acetate in 2 can be best described as trigonal bipyramidal. The secondary amine-N of adipn, the O-atom of the unidentate acetate and the midpoint of the two O-atoms of the bidentate acetate occupy the three equatorial positions and two imine-N atoms of adipn lie in axial sites. In the crystal lattice, molecules of 1 exist as discrete dimers due to intermolecular hydrogen bonding and π–π interactions. In contrast, self-assembly of 2 via intermolecular π–π interactions leads to a one-dimensional supramolecular structure.     

A new two‐dimensional cadmium coordination polymer with 1H‐imidazole‐4‐carboxylate and oxalate

The title compound, poly[aqua(μ₂‐1H‐imidazole‐4‐carboxylato‐κ³N³,O:O′)hemi(μ₂‐oxalato‐κ⁴O¹,O²:O^1′,O^2′)cadmium(II)], [Cd(C₄H₃N₂O₂)(C₂O₄)_0.5(H₂O)]_n, exhibits a two‐dimensional network. The Cd^II cation is coordinated to one N atom and two carboxylate O atoms from two 1H‐imidazole‐4‐carboxylate (Himc) ligands, two carboxylate O atoms from the bridging oxalate anion and one ligated water molecule; these six donor atoms form a distorted octahedral configuration. The oxalate anion lies on a centre of inversion. The Himc ligands connect the Cd^II cations to form –Cd–Himc–Cd–Himc–Cd– zigzag chains, with a Cd...Cd separation of 5.8206 (6) Å along the b direction, which are further linked by tetradentate oxalate anions to generate a two‐dimensional herringbone architecture in the ab plane. These layers are extended to form a three‐dimensional supramolecular framework via O—H...O and N—H...O hydrogen bonds and π–π stacking interactions. The solid‐state photoluminscent behaviour of the title compound has been investigated at room temperature.