Synthesis,structural and spectroscopic characterization of a new cadmium(II) complex containing imidazole (Im) as ligand, [Cd(Im)6](ClO4)2

Reaction between the 1,1′-carbonyldiimidazole ligand and mixtures of cadmium(II) acetate with sodium perchlorate provided the unusual crystalline material [Cd(Im)₆](ClO₄)_2, (Im?=?imidazole). This new Cd^II complex, has been characterized by elemental analysis, IR-, ¹H NMR-, ¹³C NMR and ¹¹³Cd NMR spectroscopy. The coordination number in this complex is six, CdN₆ and coordination environment around the Cd(II) may be described as distorted octahedral with a D_2h point group. There are both edge-to-face π–π stacking and C–H(Im)?···?π interactions between aromatic “Im” rings belonging to adjacent chains in this network.     

Two new lead(II) nitrite complexes,crystal structure of [Pb(phen)2(NO2)2] an eight-coordinate lead(II) complex

Two new lead(II) complexes containing nitrite, [Pb(L)₂(NO₂)₂], L?=?1,10-phenanthroline (phen) or 2,2′-bipyridine (bpy), have been synthesized and characterized. The crystal structure of [Pb(phen)₂(NO₂)₂] shows monomeric units. The coordination number is eight (four from “phen” ligands and four nitrite anions), weak interaction of lead(II) with oxygen atoms of adjacent molecules produce dimer units in the solid state. The arrangement of ligands exhibits a coordination hole around the lead(II), occupied possibly by a stereoactive lone pair of electrons on lead(II), and the coordination around lead is hemidirected. There is a π–π stacking interaction between the parallel aromatic rings that may help to increase the “gap” around lead(II).     

Synthesis and structural studies of Co(II), Ni(II) and Cd(II) complexes with 2-acetylpyridine

Three new mononuclear complexes [Co(2-Acpy)₂(H₂O)₂](NO₃)₂ (1), [Ni(2-Acpy)₂(H₂O)₂](NO₃)₂ (2) and [Cd(2-Acpy)₂(NO₃)₂] (3) (2-Acpy = 2-acetylpyridine) have been synthesized and characterized by elemental analysis, IR and UV–Vis spectroscopy. The structures of 1 and 3 were accomplished by single crystal X-ray diffraction. Crystallographic investigation of 1 reveals monomeric, dicationic units in which the cobalt(II) ion is six-coordinate. The coordination sphere is formed by two N, O bidentate acetylpyridine ligands and two water molecules. The crystal structure of 3 consists of monomeric units in which the cadmium is eight-coordinate. Both the organic ligand and nitrate groups are bidentate chelators. The supramolecular solid-state architecture is sustained by π–π interactions.     

Synthesis,characterization, and fluorescence properties of dinuclear cadmium(II) complexes

Four dinuclear cadmium(II) complexes, [Cd₂(L¹)(μ₂-Cl)Cl₂] (1), [Cd₂(L²)(μ₂-Cl)Cl₂] (2), [Cd₂(L³)(μ₂-Cl)Cl₂] (3), and [Cd₂(L⁴)₃ClO₄] (4), where HL¹ = 4-methyl-2,6-bis(1-(2-piperidinoethyl)iminomethyl)-phenol, HL² = 4-methyl-2,6-bis(1-(2-pyrrolidinoethyl)iminomethyl)-phenol, HL³ = 4-methyl-2,6-bis(1-(2-morpholinoethyl)iminomethyl)-phenol and HL⁴ = 4-methyl-2,6-bis(cyclohexylmethyl)iminomethyl)-phenol, were synthesized. They were characterized by elemental analysis, FT-IR, UV–Vis, fluorescence and electronspray ionization mass spectroscopy. Complexes 1 and 4 were also characterized by single crystal X-ray analysis. The cadmiums atoms in 1 are linked by μ₂-chloride in a distorted square pyramidal geometry, whereas cadmium atom in 4 is in a distorted octahedral environment. The complexes show emission bands around 500 nm with excitation at 395 nm.     

Synthesis and structural characterization of Ni(II) complexes containing a heterocyclic NO donor ligand

Five novel nickel(II) complexes have been successfully synthesized with a heterocyclic ligand, Opdac, [Ni(Opdac)₂]Cl₂ (1), [Ni(Opdac)₂(CH₃OH)₂]Br₂(CH₃OH)₂ (2), [Ni(Opdac)₂]I₂ (3), [Ni(Opdac)₂NO₃]NO₃ (4) and [Ni(Opdac)₂ClO₄]ClO₄ (5) where Opdac = 4-(1-H-1,3-benzimidazole-2-yl)-1,5-dimethyl-2-phenyl-1-2-dihydro-3-H-pyrazol-3-one. All the complexes were characterized by elemental analysis, molar conductivity, CHN analysis, magnetic susceptibility measurements, spectroscopic studies and TG/DTA methods. In all the complexes, Opdac acts as a bidentate ligand coordinating to Ni(II) ion via the benzimidazole imine nitrogen and the pyrazolone oxygen atoms. The complexes 1 and 3 have a tetrahedral geometry while 2, 4 and 5 have an octahedral geometry around the Ni(II) center.     

Synthesis,characterization, and single crystal X-ray structure of the 1-furoyl-3-cyclohexylthiourea cadmium chloride complex,Cd[C4H3OC(O)NHC(S)NHC6H11]4Cl2

Cadmium chloride complex of 1-furoyl-3-cyclohexylthiourea (CyTu) was prepared and characterized by elemental analysis, IR, and Raman spectroscopy. The structure of the complex was determined by single crystal X-ray methods (space group Bbab, a = 20.918(1), b = 23.532(1), c = 23.571(1) Å, α = β = γ, Z = 8). Each cadmium has distorted octahedral geometry, coordinated by two chlorides and the thiocarbonyl sulfurs from four CyTu molecules. All the spectroscopic data are consistent with coordination of CyTu by sulfur to cadmium.     

Synthesis,characterization and crystal structures of Ni(II), Cd(II) complexes with N -(2-propionic acid)-salicyloyl hydrazone and bipy/phen

The ligand N-(2-propionic acid)-salicyloyl hydrazone(H₃L, 1) and its new transition metal(II) complexes [NiHL(bipy)H₂O] (2), [CdHL(bipy)(H₂O)₂]₂·2H₂O (3) and [NiHL(phen)H₂O]·H₂O (4) (HL is a dianion, bipy?=?2,2′-bipyridine and phen?=?1,10-phenanthroline) were synthesized and characterized on the basis of elemental analyses, IR, ¹H NMR, molar conductivity and thermal analysis. Single crystal X-ray diffraction showed that 1 is in keto form and connected by hydrogen bonds to form a two-dimensional supermolecular compound. Complexes 2 and 4 have the same structure with distorted meridional octahedral geometry with 1 as a tridentate ligand with keto-form coordination by azomethine, carboxyl O and acyl O. In 3, ligand 1 bridges two Cd(II) atoms by μ ₂-O of carboxyl. H-bonding is an important weak interaction for constructing supermolecular frameworks. There are π–π interactions between bipy or phen rings in 3 or 4, respectively.     

Syntheses,characterizations and crystal structures of two new complexes, [Co2(CH2 =C(CH3)CO2)4(phen)2(H2O)2] and [Pb2(CH2 =C(CH3)CO2)4(phen)2]

Two new complexes, [Co₂(CH₂=C(CH₃)CO₂)₄(phen)₂(H₂O)₂] (1) and [Pb₂(CH₂=C(CH₃)CO₂)₄(phen)₂] (phen = 1,10-phenanthroline) (2), have been synthesized and structurally characterized by single crystal X-ray diffraction methods. There are two cocrystallized conformers of [Co(CH₂=C(CH₃)CO₂)₂(phen)(H₂O)] in the asymmetric unit of 1 with the Co atoms displaying similar coordination modes. In the asymmetric unit of 2, there exist two crystallographically independent [Pb(CH₂=C(CH₃)CO₂)₂(phen)] molecules with the Pb atoms showing completely different coordination geometries. Weak intermolecular interactions such as hydrogen bonding and π–π stacking are responsible for the supramolecular assembly and stabilization of the crystal structures of 1 and 2. The complexes are characterized by elemental analysis, IR spectra, and UV–Vis spectra. The fluorescent properties of 2 are also discussed.     

Synthesis,spectroscopic, structural characterization of Cd(II) and Zn(II) complexes based on the N-methyl-C-(2-pyridyl)nitrone

Zinc and cadmium complexes, ML₂(NO₃)₂ (L = N-methyl-C-(2-pyridyl)nitrone) were synthesized and characterized by means of X-ray diffraction crystallography and IR and NMR spectroscopy. The organic ligands in the complexes are coordinated via the oxygen atom of the nitrone group and the nitrogen atom of the pyridine moiety. The coordination environment of the central atoms is a distorted octahedron. The bond lengths and angles of the complexes were calculated using the DFT method with B3LYP functional. Theoretical studies revealed that the geometric parameters are in agreement with the experimental data. The fluorescent properties for the zinc and cadmium complexes were investigated at room temperature.     

Synthesis and spectral studies of cadmium(II) complexes derived from di-2-pyridyl ketone and N-phenylsemicarbazide: First structural report of a cadmium(II) complex of semicarbazone

A new semicarbazone (HL) based on di-2-pyridyl ketone and its three cadmium(II) complexes [CdL(CH₃COO)]₂ · 2CH₃OH (1), Cd(HL)Br₂ (2) and [Cd₂L₂N₃]₂ · H₂O (3) were synthesized and characterized by different physicochemical techniques. The complex, [CdL(CH₃COO)]₂ · 2CH₃OH (1) is having a dimeric structure. In complexes 1 and 3, the ligand moieties are coordinated as monoanionic (L⁻) forms and in complex 2, the ligand is coordinated as neutral (HL) one. The coordination geometry around cadmium(II) in 1 is distorted octahedral, as obtained by X-ray diffraction studies.     

Syntheses and characterization of nickel(II), zinc(II) and palladium(II) complexes derived from three pyrazole-based polydentate ligands

Two pyrazole-based polydentate ligands, 1,3-bis(5-methyl-3-phenylpyrazol-1-yl)-propan-2-ol (Hmppzpo) and 1,3-bis(5-methyl-3-p-isopropylphenylpyrazol-1-yl)-propan-2-ol (Hmcpzpo), have been synthesized. A third ligand, 1,3-bis(3,5-dimethylpyrazol-1-yl)-propan-2-ol (Hdmpzpo), has been synthetically modified. Seven new M(II) coordination compounds of general formula M₂L₂X₂ (M?=?Zn, Ni; X?=?NO₃ or ClO₄; L?=?dmpzpo, mppzpo or mcpzpo) or MLX (M?=?Pd; L?=?dmpzpo; X?=?Cl) were synthesized and structurally characterized by elemental analysis and FT-IR analysis. The crystal structures of [Zn₂(μ-dmpzpo-O,N,N′)₂(NO₃)₂]?·?2H₂O (1?·?2H₂O), [Ni₂(μ-dmpzpo-O,N,N′)₂(CH₃CN)₂](ClO₄)₂ (2) and Pd(μ-dmpzpo-N,N′)Cl₂ (4) were determined by single-crystal X-ray crystallography. The crystal structures show that complexes 1?·?2H₂O and 2 are center-symmetric dinuclear compounds, with two metal ions bridged by two alkoxo groups and each metal ion with a distorted square-pyramidal environment. The palladium complex, 4, displayed square-planar coordination geometry around the Pd(II) ion with trans arrangement.     

Synthesis and characterization of mononuclear copper(II) and cadmium(II) complexes with di-(2-picolyl)sulfur

The reaction of Cu(ClO₄)₂·6H₂O and Cd(ClO₄)₂ with di-(2-picolyl)sulfur (dps) leads to the formation of mononuclear complexes [Cu(dps)(H₂O)(ClO₄)](ClO₄) (1) and [Cd(dps)₂](ClO₄)₂ (2). The crystal structure of 1 exhibits a distorted square pyramidal geometry, coordinated by one sulfur and two nitrogen atoms from the dps ligand, one water molecule and one perchlorate oxygen atom. For 2, the environment around cadmium atom is in a distorted octahedron with four nitrogen and two sulfur atoms from the dps ligand. Cyclic voltammetric data show that complexes undergo two waves of a one-electron transfer corresponding to M(II)/M(III) and M(II)/M(I) processes. Spectral and electrochemical behaviors of the complexes are also discussed.     

Three new thiocyanato-bridged complexes of cadmium(II): syntheses,X-ray crystal structures and thermal properties

Three new thiocyanato-bridged polymers of cadmium(II), [Cd(me₄dpt)(SCN)₂] _n (1) [me₄dpt = 3,3′-iminobis(N,N-dimethylpropylamine], [Cd(me₂tn)(SCN)₂] _n (2) (me₂tn = N,N′-dimethyl-1,3-propanediamine) and [{amphyH} {Cd(SCN)₃}] _n (3) (ampyH = 4-aminopyridinium cation), have been synthesized and their molecular structures determined through X-ray crystallography. In Complex 1 each square pyramidal mononuclear fragment is H-bonded (N ? H…S) to form a 1D supramolecular chain. Complex 2 is a 1D coordination polymer in which each distorted octahedral cadmium(II) ion is linked with the four bridging thiocyanates and one diamine. The structure of 3 reveals anionic [Cd(SCN)₃]^? zigzag chains arranged in an approximately hexagonal array with the 4-aminopyridinum cations occupying triangular channels. Each chain is H-bonded (N?H…N) to form a 2D supramolecular network. Upon heating, 1 and 2 melt and transform to transparent solid masses at ambient temperature over a few days. On scratching, these turn to a fine powder. This phenomenon is repeatable. Complex 3 upon heating loses a 4-aminopyridine molecule and transforms to [H][Cd(SCN)₃] at ??195°C.     

Syntheses,crystal structures,and photoluminescence of two Cd(II) complexes with simple ligands

Two cadmium complexes, {[Cd₂(2,5-tda)₂(ip)₄]·4H₂O}_n (1) and {[Cd₂(4,4′-obb)₂(ip)₂·H₂O]·H₂O}_n (2) (2,5-tda?=?thiophene-2,5-dicarboxylic acid, 4,4′-obb?=?4,4′-oxybisbenzoic acid, ip?=?1H-imidazo[4,5-f][1, 10]-phenanthroline), were synthesized and characterized by IR, elemental analysis, powder X-ray diffraction, and single-crystal X-ray diffraction. X-ray analysis revealed that 1 is a dinuclear complex with the 2,5-tda anion connecting two Cd ions in a μ₁-η¹:η⁰/μ₁-η¹:η⁰ coordination mode. Each dinuclear complex is further connected with neighboring complexes via hydrogen-bonding interactions. Compound 2 displays a 2-D layer structure with opened windows occupied by crystallographic water molecules. The layers are further packed via hydrogen-bonding interactions. Luminescent properties for 1 and 2 are also investigated in the solid state at room temperature.     

Synthesis and structural characterization of Ni(II) complexes with the chiral CpH(PNMent) tripod ligand

Treatment of NiCl₂ with the tripod ligand (L_Ment,S_C)-1H led to (L_Ment,S_C)-[Cp(PN_Ment)NiCl] in which the potentially tridentate ligand coordinated to the metal center in a bidentate way via the cyclopentadienyl system and the phosphorus atom. In the presence of NH₄PF₆ [(L_Ment,S_C)-[Cp(PN_Ment)NiCl] readily underwent Cl/PPh₃ exchange to give (L_Ment,S_C)-[Cp(PN_Ment)NiPPh₃]PF₆. Reaction of (L_Ment,S_C)-[Cp(PN_Ment)NiCl] with 0.5 eq. of dppe afforded [{(L_Ment,S_C)-[Cp(PN_Ment)Ni]}₂dppe](PF₆)₂. (L_Ment,S_C)-[Cp(PN_Ment)NiPPh₃]PF₆ and [{(L_Ment,S_C)-[Cp(PN_Ment)Ni]}₂dppe](PF₆)₂ were characterized by NMR and MS spectroscopy, and also by single crystal X-ray diffraction. The cyclopentadienyl ligand of (L_Ment,S_C)-[Cp(PN_Ment)NiPPh₃]PF₆ shows a distortion intermediate between the ene-allyl and diene types, while the two cyclopentadienyl ligands of [{(L_Ment,S_C)-[Cp(PN_Ment)Ni]}₂dppe](PF₆)₂ have intermediate and diene distortions, respectively. According to the temperature dependent NMR spectra of (L_Ment,S_C)-[Cp(PN_Ment)NiPPh₃]PF₆ and [{(L_Ment,S_C)-[Cp(PN_Ment)Ni]}₂dppe](PF₆)₂ two different conformations of the tether in the Cp(PN_Ment)Ni system could be frozen out at low temperatures.     

Synthesis and spectroscopic characterization of cadmium(II) complexes of thiones and thiocyanate

Cadmium(II) complexes of thiones and thiocyanate, [(>C=S)₂Cd(SCN)₂], have been prepared and characterized by IR and NMR spectroscopy. An upfield shift in the >C=S resonance of thiones in the ¹³C NMR and downfield shift in N–H resonance in ¹H NMR are consistent with sulfur coordination to cadmium(II). The presence of ν(N–H) of thiones in IR spectra of the complexes indicates the thione forms of the ligands in the solid state; some contribution of the thiolate form was observed in one complex. The appearance of a band around 2100 cm^?1 in IR and a resonance around 132 ppm in ¹³C NMR indicates the binding of thiocyanate to cadmium(II).     

Syntheses and crystal structures of phthalato-, succinato-, maleato-, acetylenedicarboxylato-bridged [bis(2-pyridylcarbonyl)amide]copper(II) complexes

Self-assemblies of the 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) and Cu(OH)₂ in the presence of dicarboxylate ligands yielded four new complexes, [Cu₄(bpca)₄(L1)₂(H₂O)₂]·5H₂O (1), [Cu₂(bpca)₂(L2)(H₂O)₂]·2H₂O (2), [Cu₂(bpca)₂(L3)(H₂O)₂]·H₂O (3), and [Cu₂(bpca)₂(L4)(H₂O)₂]·3H₂O (4) (bpca = bis(2-pyridylcarbonyl)amide anion, H₂L1 = phthalic acid, H₂L2 = succinic acid, H₂L3 = maleic acid, H₂L4 = acetylenedicarboxylic acid). Their structures were determined by single-crystal X-ray diffraction analyzes and further characterized by IR spectra and thermogravimetric analyzes. The five-coordinate Cu ions in 1 are bridged by phthalate to form 1-D chains, which are assembled into 3-D frameworks by extensive hydrogen bonds. Compounds 2–4 possess similar structures, built up of [Cu₂(bpca)₂(L)(H₂O)₂] (L = L2 for 2, L3 for 3, L4 for 4) and lattice molecules. The 3-D frameworks of 2–4 are completed by hydrogen bond interactions.     

Cd(II) complexes based on a tricarboxylate: synthesis,structural characterization and properties

Reactions of cadmium(II) with 5-(4-carboxybenzylamino)isophthalic acid (H₃L) in the presence of 2-(pyridin-2-yl)-1H-benzo[d]imidazole (pybim) and 2,2′-bipyridine (bpy) by hydrothermal method lead to two complexes, [Cd(HL)(pybim)]·H₂O (1) and [Cd₂(L)(HCOO)(bpy)₂(H₂O)]·H₂O (2). Complexes 1 and 2 have been characterized by single-crystal and powder X-ray diffraction, Infrared spectra, and elemental and thermogravimetric analyses. 1 has a double-chain structure while 2 consists of uninodal 3-connected 2-D hcb networks with (6³) topology. Luminescence and sorption properties of 1 and 2 were also investigated.     

SYNTHESIS AND STRUCTURES OF DICHLOROTETRAKIS-(PHENYLTHIOUREA) CADMIUM(II) AND CATENA-BIS(THIOCYANATE) BIS(PHENYLTHIOUREA)CADMIUM(II)

Abstract

Two new cadmium(II) complexes with phenylthiourea (PTU), namely Cd(PTU)₄Cl₂ (1) and [Cd₂(NCS)₂(μ₂-SCN)₂(PTU)₂(μ₂-PTU)₂] _n (2), have been prepared and characterized structurally by X-ray diffaction. Complex 1 crystallizes in the monoclinic space group C2/c, with a = 27.057(13), b = 8.108(3), c = 16.751(8) Å, β = 114.46°, V = 3345(3) ų, Z = 4. Complex 2 crystallizes in the triclinic space group P-1, with a = 9.336(3), b = 14.686(5), c = 16.911(5) Å, α = 71.36(2), β = 84.31(2), γ = 72.470(10)°, V = 2095.0(12) ų Z = 4. The structural analysis shows that each metal atom in both the mononuclear complex 1 and polynuclear complex 2 is octahedrally coordinated by four sulfur atoms and two chloro ligands or two nitrogen atoms from the thiocyanate groups, respectively. The PTU ligand can serve as either a monodentate ligand or a μ₂-bridging ligand upon coordination to a metal atom.