Self-assembled copper(II) coordination polymers derived from aminopolyalcohols and benzenepolycarboxylates: structural and magnetic properties

The new copper(II) or copper(II)/sodium(I) 1D coordination polymers [Cu2(Hmdea)2(mu-H2O)(mu2-tpa)]n.2nH2O (1), [Cu2(H2tipa)2(mu2-ipa)]n.4nH2O (2), [Cu2(H2tea)2Na(H2O)2(mu2-tma)]n.6nH2O (3), [Cu2(H2tea)2(mu2-ipa)]n.nH2O (4a), and [Cu2(H2tea)2{mu3-Na(H2O)3}(mu3-ipa)]n(NO3)n.0.5nH2O (4b) have been prepared in aqueous medium by self-assembly from copper(II) nitrate, aminopolyalcohols [methyldiethanolamine (H2mdea), triisopropanolamine (H3tipa), and triethanolamine (H3tea)] as main chelating ligands and benzenepolycarboxylic acids [terephthalic (H2tpa), isophthalic (H2ipa), and trimesic (H3tma) acid] as spacers. They have been characterized by IR spectroscopy, elemental and single-crystal X-ray diffraction analyses, the latter indicating the formation of unusual multinuclear metal cores interconnected by various benzenepolycarboxylate spacers, leading to distinct wavelike, zigzag, or linear 1D polymeric metal-organic chains. These are further extended to 2D or 3D hydrogen-bonded supramolecular networks via extensive interactions with the intercalated crystallization water molecules. The latter are associated, also with aqua ligands, by hydrogen bonds resulting in acyclic (H2O)3 clusters in 1, (H2O)8 clusters in 2, infinite 1D water chains in 3, and disordered water-nitrate associates in 4b, all playing a key role in the structure stabilization and its extension to further dimensions. Variable-temperature magnetic susceptibility measurements have shown that 1-4 exhibit a moderately strong ferromagnetic coupling through the alkoxo bridge. The small Cu-O-Cu bridging angle and the large out-of-plane displacement of the carbon atom of the alkoxo group accounts for this behavior. The magnetic data have been analyzed by means of a dinuclear and a 1D chain model, and the magnetic parameters have been determined. The magnetic exchange coupling in 3, to our knowledge, is the highest found in alkoxo-bridged copper(II) complexes.     

Cobalt(II), nickel(II) and zinc(II) coordination compounds derived from aromatic amines

The structural and spectroscopic characterization of coordination compounds of four aromatic amines derived from benzimidazole, 2-aminobenzimidazole (L1), 1-(S-methylcarbodithioate)-2-aminobenzimidazole (L2), 2-(2-aminophenyl)-1H-benzimidazole (L3) and 6,6-dimethyl-5H-benzimidazolyl[1,2-c]quinazoline (L4) are reported. Cobalt(II) [Co(L1)₂(CH₃COO)₂] (1) and nickel(II) [Ni(L1)₂(CH₃COO)₂] (2) acetate coordination compounds of L1 are discussed. The synthesis and the X-ray crystal structure of the new 1-(S-methylcarbodithioate)-2-aminobenzimidazole (L2) is informed, together with its cobalt(II) [Co(L2)₂Cl₂] (3), [Co(L2)₂Br₂] (4) and zinc(II) [Co(L2)₂Cl₂] (5), [Zn(L2)₂Br₂] (6) coordination compounds. In these compounds the imidazolic nitrogen is coordinated to the metal center, while the ArNH₂ and the S-methylcarbodithioate groups do not participate as coordination sites. A co-crystal of L1 and L2 is analyzed. Structural analyses of the coordination compounds of L3 showed that this ligand behaves as a bidentate ligand through the aniline and the imidazole groups forming six membered rings in the cobalt(II) [Co(L3)Cl₂] (7) and zinc(II) [Zn(L3)Cl₂] (8) compounds, as well as the nickel(II) nitrate [Ni(L3)₂(H₂O)₂](NO₃)₂ (9). The quinazoline L4 was produced by insertion of one acetone molecule and water elimination in L3, its X-ray crystal diffraction analysis, as well as that of its zinc(II) coordination compound [Zn(L4)₂Cl₂] (10), are discussed.     

Palladium(II) coordination and cyclometallated complexes derived from 1-tert-butylpyrazole

The synthesis and characterization of a number of new coordination compounds of Pd^II with the nitrogen donor 1-tert-butylpyrazole (^tBuPzH) are described. Compounds are trans-[Pd(^tBuPzH)₂Cl₂] and the cyclometallated structures [Pd₂(^tBuPz)₂(AcO)₂] and [Pd₃(^tBuPz)₂(AcO)₄]. All these complexes are mixtures of syn and anti isomers. Also, the chloro-bridged complex [Pd₂(^tBuPz)₂Cl₂] has been isolated as an equilibrium mixture of cis and trans isomers. The compounds have been studied by variable temperature ¹H- and ¹³C-NMR spectroscopy.     

Nickel(II) complexes containing bidentate amido phosphine ligands derived from alpha-iminophosphorus ylides: synthesis and structural characterization

The reactions of prop-2-ynyltriphenylphosphonium bromide with a series of primary aromatic or aliphatic amines in refluxing acetonitrile generated the corresponding 2-hydrocarbylaminoprop-1-enyltriphenylphosphonium bromide [RNHC(Me)=CHPPh(3)]+Br- (R = 2,6-C(6)H(3)iPr(2) (1a), 2,6-C(6)H(3)Me(2) (1b), Ph (1c), t-Bu (1d)) as crystalline solids. Deprotonation of 1a-d with NaH in THF at -35 degrees C afforded the alpha-iminophosphorus ylides RN=C(Me)CH=PPh(3) (2a-d) in high yield. Spectroscopic and crystallographic data of 2 suggest a strong intramolecular interaction between the imino nitrogen and the phosphorus atom. In contrast to N-arylated 2a-c, the N-tert-butyl-derived 2d is extremely moisture-sensitive. Hydrolysis of 2d led to elimination of benzene and generated concomitantly the phosphine oxide 3d that contains an ene-amine functionality. The reactions of 2a-c with Ni(COD)(2) in the presence of an excess amount of pyridine in toluene produced the divalent nickel complexes of the type [kappa(2)-RNC(Me)=CHPPh(2)]Ni(Ph)(Py) (4a-c). The solution and solid-state structures of these new compounds are presented.     

Nanoparticles of a new mercury(II) coordination polymer: synthesis,characterization, thermal and structural studies

Nanoparticles of a new Hg(II) one-dimensional coordination polymer, {[Hg(4-bpdb)I₂] _n , 4-bpdb?=?1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene} were synthesized by reaction of HgI₂ and 4-bpdb by a sonochemical method. The new nanoparticles were characterized by scanning electron microscopy, X-ray powder diffraction (XRD) and FT-IR spectroscopy; [Hg(4-bpdb)I₂] _n was structurally characterized by single crystal X-ray diffraction. This compound consists of one-dimensional polymeric units of [Hg(4-bpdb)I₂]. The thermal stability of [Hg(4-bpdb)I₂] _n was studied by thermal gravimetric (TG) and differential thermal analyses (DTA).     

Secondary bonding in functionalized organotellurium compounds: preparation and structural characterization of bis(acetamido)tellurium(IV) diiodide and bis(4-methylbenzoylmethyl)tellurium(II)

Elemental tellurium inserts, under mild conditions, between C-I bond of iodoacetamide to afford bis(acetamido)tellurium(IV) diiodide (NH₂COCH₂)₂TeI₂, 1. Heating of N-bromomethylphthalimide with activated tellurium powder however, resulted in the formation of bis(phthalimido)methane, 2, instead of the expected product bis(phthalimidomethyl)tellurium(IV) dibromide. The IR spectrum of 1 is indicative of intramolecular Te?OC interaction which is also substantiated by its single-crystal structure. The compound with planar small-bite chelating organic ligands acquires butterfly shape that imparts almost perfect C_2v molecular symmetry but unlike other organotellurium(IV) iodides, the solid state structure of 1 is devoid of any intermolecular Te?I or I?I secondary interactions owing to the presence of intramolecular Te?O secondary bonds as well as intermolecular N-H?O, N-H?I and C-H?I hydrogen bonds. Bis(4-methylbenzoylmethyl)telluride (4-MeC₆H₄COCH₂)₂Te, 3b, prepared by the reduction of the corresponding dibromide, is the first structurally characterized acyclic dialkyltelluride and interestingly, does not involve intramolecular Te?OC interaction invariably present in the parent dihalides (4-YC₆H₄COCH₂)₂TeX₂ (Y = H, X = I 4a; Y = H, X = Br 5a; Y = MeO, X = Br 5c). Weak intermolecular Te?Te and C-H?O hydrogen bonds appear to be the non covalent intermolecular associative forces that dominate its crystal packing in the solid state of this Te(II) derivative. The dialkyltellurides (4-YC₆H₄COCH₂)₂Te, (Y = H, 3a, Me, 3b) undergo oxidation in presence of (SCN)₂ to give the corresponding bis(isothiocyanato)tellurium(IV) derivatives and form 2:1 adducts with Pt(II) and Pd(II) chlorides.     

Four Zn(II)/Cd(II) coordination polymers derived from isomeric benzenedicarboxylates and 1,6-bis(triazol)hexane ligand: synthesis,crystal structure,and luminescent properties

Four coordination polymers, [Zn(o-bdc)(bth)_0.5(H₂O)] _n (1), [Cd(o-bdc)(bth)_0.5(H₂O)] _n (2), [Zn(m-bdc)(bth)] _n (3), and [Cd(p-bdc)(bth)?·?(H₂O)₂] _n (4) (where o-bdc?=?1,2-benzenedicarboxylate, m-bdc?=?1,3-benzenedicarboxylate, p-bdc?=?1,4-benzenedicarboxylate, and bth?=?1,6-bis(triazol)hexane), have been hydrothermally synthesized and structurally characterized. Both 1 and 2 are isostructural, featuring two binodal architectures: (6³)(6⁵·8) topology in terms of o-bdc and Zn^II/Cd^II as three- and four-connected nodes. Complex 3 shows a 2-D (4,4) network with the Zn?···?Zn?···?Zn angle of 57.84°, whereas 4 exhibits planar 2-D (4,4) network. These 2-D networks of 3 and 4 are extended by supramolecular interactions, such as CH?···?π/π–π stacking and hydrogen-bonding into 3-D architecture. A structural comparison of these complexes demonstrates that the dicarboxylate building blocks with different dispositions of the carboxyl site play a key role in governing the coordination motifs as well as 3-D supramolecular lattices. Solid-state properties such as photoluminescence and thermal stabilities of 1–4 have also been studied.     

Nanoparticles of a new zinc(II) coordination polymer: synthesis,characterization, thermal,and structural studies

Nanoparticles of a Zn(II) coordination polymer {[Zn(DADMBTZ)(CH₃COO)₂] _n , DADMBTZ?=?2,2′-diamino-5,5′-dimethyl-4,4′-bithiazole} were synthesized by reaction of Zn(NO₃)₂?·?4H₂O, CH₃COONH₄ and DADMBTZ by a sonochemical method. The nanoparticles were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. [Zn(DADMBTZ)(CH₃COO)₂] _n was structurally characterized by single-crystal X-ray diffraction. In this four-coordinate compound with nearly C₂ symmetry, DADMBTZ is bidentate. The metal lies in a pseudo-tetrahedral environment and is ligated by the two bithiazole ring nitrogen atoms and an oxygen from each of the two monodentate acetates; 2-D networks are formed via N–H···O hydrogen bonds. Thermal stability of [Zn(DADMBTZ)(CH₃COO)₂] _n was studied by thermal gravimetric and differential thermal analyses. A ZnO nanostructure was obtained by direct thermolyses at 500°C under air. The ZnO nanostructure was characterized by SEM, XRD, and FT-IR spectroscopy.     

Palladium(II) coordination and cyclometallated complexes derived from 3- and 5-aryl-substituted pyrazoles

Palladium(II) coordination complexes of nine 3- or 5-arylpyrazoles (phenyl, 2-bromophenyl, or 3-methoxyphenyl), as well as of 3,5-diphenylpyrazole, are reported. A cis-trans mixture of [PdL₂Cl₂] isomers is found in the case of 3-aryl-1-methylpyrazoles, the cis-isomers being transformed into trans by heating. Only trans isomers are isolated with the other ligands. Cyclopalladation of 3-ary]-1-methylpyrazoles can be performed with palladium(II) acetate, and the resultant μ-acetate bridged dimers can be transformed into μ-chloro bridged dimers or acetylacetonate monomers. The structures of the complexes have been characterized by ¹H- and ¹³C-NMR spectroscopy.     

Synthesis and structural investigations of some alkylamine pentacyanoferrate(II) complexes

A series of alkylamine pentacyanoferrate(II) complexes, Na₃[Fe(CN)₅L]·(H₂O)_x, where L = (CH₃)₂NH, (C₂H₅)₂NH, (C₃H₇)₂NH, (C₄H₉)₂NH, (C₆H₅)₂NH, (C₂H₅)₃N, (C₄H₉)₃N or C₆H₁₁NH₂, were synthesized and characterized by analysis, magnetic, IR and Mössbauer spectroscopic studies. Characteristic CN and FeCN vibrational frequencies were found to be affected by the nature of the substituent. Mössbauer spectra exhibited a two-line quadrupole doublet with isomer shifts (δ) − 0.04 to 0.49 mm s⁻¹ (relative to sodium nitroprusside) and quadrupole splitting (ΔE_Q) of 0.73–1.92 mm s−1. A correlation of δ vs ΔE_Q has been attempted and the sign of the electric field gradient predicted. Bonding characteristics seem to change from simple mono- and dialkylamines to bulky di- and trialkylamines in pentacyanoferrate(II) complexes.     

Hydrothermal synthesis,crystal structures,and photoluminescent properties of two cadmium(II) coordination polymers derived from dicarboxylates and N-donor ligands

Two metal coordination polymers, [Cd(ipa)(L₁)(H₂O)]_n (1) and [Cd(ipa)(L₂)]_n (2) [H₂ipa?=?isophthalic acid, L₁?=?3,5-bis(imidazole-1-yl)pyridine and L₂?=?3,5-bis(benzoimidazo-1-ly)pyridine], have been synthesized and structurally characterized by IR, elemental analysis, XRD, and X-ray single-crystal diffraction. Complex 1 shows a twofold cds topological net and 2 features a 3-D pcu topological net. Luminescent properties of 1 and 2 were investigated in the solid state at room temperature.     

Sonochemical synthesis and structural characterization of a nano-structure Pb(II) benzentricarboxylate coordination polymer: new precursor to pure phase nanoparticles of Pb(II) oxide

Microcrystals of a new Pb(II) coordination polymer, [Pb₂(1,3,5-HBTC)₂(H₂O)₄] · H₂O (1) (1,3,5-H₃BTC = 1,3,5-benzentricarboxylic acid), was synthesized by a sonochemical method. The structure was characterized by scanning electron microscopy, X-ray powder diffraction, elemental analyses, and IR spectroscopy. Thermal stability was studied by thermal gravimetric and differential thermal analyses. After the calcination of nanosized 1 at 400°C, pure phase nanosized Pb(II) oxide has been produced.     

One- and two-dimensional cobalt(II) coordination polymers derived from flexible bis(benzimidazole) and aromatic carboxylate co-ligands

Two new coordination polymers, formulated as [Co(L1)(btec)_0.5] _n (1) and {[Co(L2)(bdc)]·H₂O} _n (2) (L1 = 1,3-bis(2-methylbenzimidazol-1-ylmethyl)benzene, H₂bdc = 1,3-benzenedicarboxylic acid, H₄btec = 1,2,4,5-benzenetetracarboxylic acid, L2 = 1,3-bis(benzimidazol-1-ylmethyl)benzene), have been hydrothermally synthesized and characterized by physicochemical and spectroscopic methods as well as single-crystal X-ray diffraction. The cobalt atoms present different environments, with a trigonal pyramidal geometry in 1 and a distorted octahedral configuration in 2. Complex 1 shows a 2D (4,4) network linked by L1 and btec^4? anions, giving an uninodal 4-connected sql topology with a point symbol of {4²·6²}, while complex 2 displays a 1D ladder-like chain structure, which is further assembled into a 3D supramolecular architecture via C–H···π hydrogen bonding interactions. The fluorescence properties of both complexes have been investigated in the solid state.     

Palladium(II)-N-heterocyclic carbene complexes derived from proline: synthesis and characterization

Pd(II)-N-heterocyclic carbene complexes derived from proline have been successfully synthesized in good yields and their structures have been characterized by X-ray single crystal diffraction. It was found that the substituents on the N-atom of the pyrrolidine skeleton dramatically affect on the coordination pattern of the palladium complexes. In a word, when an electron-rich group as benzyl group was attached on the N-atom, both of the N-atom and NHC were coordinated to the Pd(II) center; while when an electron-poor group as Ts group was attached, a dimeric mono-coordinated Pd(II)-NHC was obtained exclusively.     

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.     

Chloro-bridged complexes of copper(II) and manganese(II) derived from unsymmetric bidentate ligands: synthesis,crystal structure and characterization

Two new usymmetric bidentate Schiff-base ligands (2-pyridyl-2-furylmethyl)imine (L1) and (2-pyridyl-phenylmethyl)imine (L2) were prepared. The crystal structures of two chloro-bridged complexes [Cu₂(μ-Cl)₂(L1)₂Cl₂] (1) and [Mn (μ-Cl)₂(L2)] (2) derived from the each ligand have been confirmed by single-crystal X-ray diffraction analysis. The complexes were characterized by IR, elemental analysis and spectroscopic methods. In complex 1, the two copper atoms are five-coordinate involving a square-pyramidal geometry having a N₂Cl₃ donor set with the two chlorine atoms bridging the two copper atoms. In complex 2, the manganese atoms are both six-coordinate. In contrast to 1, all chlorine atoms in 2 are bridging chlorides and link adjacent manganese atoms together forming 1-D infinite chains.     

Tellurium(II) and tellurium(IV) complexes of phosphine chalcogenide ligands,synthesis and X-ray structures

Reaction of TeX₄ (X = Cl or Br) with 2 mol. equiv. of OPR₃ (R = Me, Et or Ph) gives the distorted octahedral cis-[TeX₄(OPR₃)₂], while the bidentates Ph₂P(E)(CH₂)_nP(E)Ph₂ (E = O, n = 1 or 2; E = S, n = 1) give the six-coordinate [TeX₄{Ph₂P(E)(CH₂)_nP(E)Ph₂}]. These species have been characterised spectroscopically (via ¹H and ³¹P{¹H} NMR and IR) and by crystallographic analyses on cis-[TeBr₄(OPPh₃)₂], [TeCl₄{Ph₂P(O)CH₂P(O)Ph₂}] and [TeBr₄{Ph₂P(S)CH₂P(S)Ph₂}]. The TeX₄ (X = Cl or Br) are reduced by Ph₂P(S)(CH₂)₂P(S)Ph₂ and Ph₂P(Se)CH₂P(Se)Ph₂, giving the planar, four-coordinate Te(II) species [Te{Ph₂P(S)(CH₂)₂P(S)Ph₂}₂]²⁺ (isolated as [(TeCl₅)₂{μ-Ph₂P(S)(CH₂)₂P(S)Ph₂}]^2? and [TeBr₆]^2? salts) and [TeBr₂{Ph₂P(Se)CH₂P(Se)Ph₂}], all of which have also been identified crystallographically. On the basis of the structural data the Te-based lone pair associated with the Te(IV) species is assumed to occupy the 5s orbital, whereas in the Te(II) complexes the planar coordination is consistent with the two stereochemically active lone pairs occupying the axial sites.