Acid dissociation of 2,2′-dipyridylamine in non-aqueous medium when chelated to some Ru(II)N4 cores

[Ru(2,2′-bipyridine)₂(Hdpa)](BF₄)₂ · 2H₂O (1), [Ru(1,10-phenanthroline)₂(Hdpa)] (PF₆)₂ · CH₂Cl₂ (2) and [Ru(4,4,4′,4′-tetramethyl-2,2′- bisoxazoline)₂(Hdpa)] (PF₆)₂ (3) are synthesized where Hdpa is 2,2′-dipyridylamine. The X-ray crystal structures of 1 and 2 have been determined. Hdpa in 1 and 2 is found to bind the metal via the two pyridyl N ends. Comparing the NMR spectra in DMSO-d₆, it is concluded that 3 has a similar structure. The pK_a values (for the dissociation of the NH proton in Hdpa) of free Hdpa and its complexes are determined in acetonitrile by exploiting molar conductance. These correlate linearly with the chemical shift of the NH proton in the respective entities.     

Effect of anions on cadmium(II) complexes with ligand 2-(pyrazin-2-yl)-1H-benzimidazole

Three new supramolecular complexes based on a 2-(pyrazin-2-yl)-1H-benzimidazole (Hpbi) and a series of Cd(II) salts have been solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction analysis. Reaction of CdCl₂·2.5H₂O with Hpbi afforded a one-dimensional chain [Cd(Hpbi)Cl₂] (1), which exhibits a three-dimensional (3-D) supramolecular architecture through intermolecular X-H···Cl (X = N and C) hydrogen bonds and π-π stacking interactions. When using CdBr₂·4H₂O instead of CdCl₂·2.5H₂O under similar reaction conditions, a bisnuclear complex [Cd(Hpbi)₂Br₂] (2) is obtained, which obviously exhibits intermolecular X-H···Br (X = N and C) hydrogen bonds and π-π stacking interactions. When CdI₂ take place of CdCl₂·2.5H₂O, a mononuclear complex, [Cd(Hpbi)₂I₂] (3), is isolated, which shows a 3D supramolecule framework formed by intermolecule hydrogen bonds and π-π packing interactions. Interestingly, the Hpbi ligand exhibits the same coordination modes in complexes 1-3. It is noteworthy that the radius of anions plays an important role in affecting the structures and luminescent intensity of the final products. The TGA for 1-3 have been investigated and discussed in detail.     

Conformational flexibility of 2,6-bis(pyrazol-1-ylmethyl)pyridine (L) in [(L)Co(H2O)3]Cl2 and [(L)Ni(H2O)2Cl]Cl·H2O. Molecular structures and non-covalent interactions

Using a non-planar tridentate ligand 2,6-bis(pyrazol-1-ylmethyl)pyridine (L⁵) two new coordination complexes [(L⁵)Co^II(H₂O)₃]Cl₂ (1) and [(L⁵)Ni^II(H₂O)₂Cl]Cl·H₂O (2) have been synthesized and structurally characterized. Complex 1 has N₃O₃ distorted octahedral environment around Co^II with coordination by L⁵ (two pyrazole and a pyridine nitrogen in a facial mode) and three water molecules. Complex 2 has N₃O₂Cl distorted octahedral geometry around Ni^II with meridional L⁵ coordination, two water molecules, and a Cl⁻ ion. Analysis of the crystal packing diagram reveals the involvement of solvent (water as metal-coordinated and as solvent of crystallization) and counteranion (Cl⁻) to play significant roles in generating 1D chains, involving O-H···Cl, and O-H···O interactions.     

Zinc and cadmium complexes of pyridyl-benzotriazole: Syntheses, structures and supramolecular interaction

Five novel complexes with two pyridine substituted benzotriazole ligands, 1-(2-pyridyl)benzotriazole (L1) and 1-(4-pyridyl)benzotriazole (L2), [Zn(L1)₂Cl₂] (1), [{Zn(L1)₂Cl₂}·(L1)₂] (2), [Zn(L2)₂Cl₂] (3), [{Zn(L2)(H₂O)₃(μ₂-SO₄)}·H₂O] (4), and [{Cd(L2)(H₂O)₃(μ₂-SO₄)}·H₂O] (5) were synthesized. The details of the structures were characterized by X-ray single crystal analysis, revealing that these complexes were assembled together via supramolecular interaction, such as, hydrogen bonding and π-π interactions. The influence of organic ligands, anions and reaction conditions in the formation of the complexes were investigated.     

Substituent dependent dimensionalities in cobalt isophthalate supramolecular complexes and coordination polymers containing dipyridylamine ligands

Hydrothermal synthesis has afforded cobalt 5-substituted isophthalate complexes with 4,4′-dipyridylamine (dpa) ligands, showing different dimensionalities depending on the steric bulk and hydrogen-bonding facility of the substituent. [Co(tBuip)(dpa)(H₂O)]_n (1, tBuip = 5-tert-butylisophthalate) is a (4,4) grid two-dimensional coordination polymer featuring 2-fold parallel interpenetration. [Co(MeOip)₂(Hdpa)₂] (2, MeOip = 5-methoxyisophthalate) is organized into 3-fold parallel interpenetrated (4,4) grids through strong N-H⁺?O⁻ hydrogen bonding. {([Co(OHip)(dpa)(H₂O)₃])₃·2H₂O}_n (3, OHip = 5-hydroxyisophthalate) possesses 1-D chain motifs. The 5-methyl derivative {[Co(mip)(dpa)]·3H₂O}_n (4, mip = 5-methylisophthalate) has a 3-D 6⁵8 cds topology. {[Co(H₂O)₄(Hdpa)₂](nip)₂·2H₂O} (5, nip = 5-nitroisophthalate) and {[Co(sip)(Hdpa)(H₂O)₄]·2H₂O} (6, sip = 5-sulfoisophthalate) are coordination complexes. Antiferromagnetic superexchange is observed in 1 and 4, with concomitant zero-field splitting. Thermal decomposition behavior of the higher dimensionality complexes is also discussed.     

Binuclear copper and zinc complexes based on polypyridyl ligand 2,3,5,6-tetra(2-pyridyl)pyrazine (tppz): Synthesis, spectral and structural characterization

The reaction of MCl₂ · 2H₂O (M = Cu, Zn) with 2,3,5,6-tetra(2-pyridyl)pyrazine (tppz) (referred hereafter as L) in 2:1 molar ratio in acetonitrile at room temperature afforded binuclear complexes [M₂(κ³-L)Cl₄] [Cu (1), Zn (2)] where the ligand is bis-tridentate manner. The complexes have been characterized by elemental analyses, FAB-MS, IR, EPR, NMR and electronic spectral studies. Solid state structures of both the [Cu₂(κ³-L)Cl₄] · 5H₂O (1), [Zn₂(κ³-L)Cl₄] · H₂O (2) have been determined by single crystal X-ray analyses. A well-resolved uudd cyclic water tetramer and water monomer were reported in the crystal host of [Cu₂(κ³-L)Cl₄] · 5H₂O (1) and [Zn₂(κ³-L)Cl₄] · H₂O (2) showing the contribution of the water cluster to the stability of the crystal host 1 and 2.     

Addition compounds of MoO2Cl2 with chiral sulfoxides. First molecular structures of dioxomolybdenum complexes bearing chiral non-racemic sulfoxide as ligand

MoO₂Cl₂(L)₂ [L = (R)-(+)-methyl-p-tolylsulfoxide (R-MeTolSO) (1), methyl-p-tolylsulfoxide (MeTolSO) (2), 2-benzenesulfinyl-1,1-diphenylethanol (BSDPE) (3), 1-benzenesulfinyl-2-methyl-2-propanol (BSMP) (4), benzenesulfinylmethyl 4-methylphenyl ketone (BSMMPK) (5)], and MoO₂Cl₂(L) [L = BSDPE (6), BSMP (7), BSMMPK (8), (S,S)-bis(p-tolylsulfinyl)methane (S,S-TolSOCH₂SOTol) (9), bis(methylsulfinyl)methane (MeSOCH₂SOMe) (10), bis(phenylsulfinyl)methane (PhSOCH₂SOPh) (11)] have been synthesized by reacting a solution of MoO₂Cl₂(H₂O)₂ in diethyl ether with the corresponding ligand. The crystal and molecular structures of 1, 2, and 9 have been established by X-ray diffraction analysis. The ability of 1 and 9 as catalysts for the enantioselective reduction of sulfoxides to sulphides and the oxidation of sulphides to sulfoxides has been examined.     

Four metal-organic networks based on benzene-1,4-dioxyacetic acid and dipyrido[3,2-a:2′,3′-c]phenazine ligand

Four structurally diverse complexes, [Cd(dppz)(bdoa)]_n (1), [Zn(dppz)(bdoa)(H₂O)]_n (2), [Fe(dppz)₂(bdoa)]_n·2nH₂O (3), and [Co₂(dppz)₂(bdoa)₂(H₂O)]_n·3nH₂O (4), where H₂bdoa = benzene-1,4-dioxyacetic acid and dppz = dipyrido[3,2-a:2′,3′-c]phenazine, have been hydrothermally synthesized. Compounds 1-4 feature chain structures. There exist π-π interactions in the structures of 1, 2 and 4. Two neighboring chains of 1 are linked through the π-π interactions into a double chain supramolecular structure. The chains of 2 and 4 are further extended by the π-π interactions to form 3D and 2D supramolecular structures, respectively. The structural differences among such complexes show that the transition metals have important influences on their structures. The photoluminescent property of complex 2 and the magnetic property of complex 4 have also been investigated.     

Mono-, di-, and tri-ruthenium complexes with the ligand 2,2′-dipyridylamide (dpa): insights into the formation of extended metal atom chains

Reactions between Hdpa (2,2′-dipyridylamine) and either RuCl₃ · xH₂O and Ru₂(OAc)₄Cl produce mono-, di-, and tri-ruthenium complexes under various conditions. The ligand Hdpa and RuCl₃ · xH₂O react in boiling DMF to form the ionic species [Ru(Hdpa)₂Cl₂]Cl (1). Reaction of Ru₂(OAc)₄Cl with molten Hdpa leads to scission of the Ru-Ru bond and formation of the vertex-sharing bioctahedral complex Ru₂(dpa)₃(OAc)_0.64Cl_1.36 (2). A mixture of both of these species results from the reaction of Ru₂(OAc)₄Cl with Hdpa and LiCl in refluxing o-dichlorobenzene/EtOH mixtures. This mixture of compounds reacts further with KOBu^t and n-butanol in refluxing naphthalene to give low yields of the extended metal atom chain (EMAC) complex Ru₃(dpa)₄Cl₂ (I).     

Versatile coordination behaviour of Ph2AsCH2AsPh2 with Ru(II)

Treatment of ‘RuCl₃ · 3H₂O’ with Ph₂AsCH₂AsPh₂ (dpam) in hot EtOH gives either trans-[RuCl₂(dpam-As,As′)(dpam-As)₂] (1), or cis-[RuCl₂(dpam-As,As′)₂] (2), depending on the mole ratio. On exposure to light, solutions of 2 isomerise to trans-[RuCl₂(dpam-As,As′)₂] (3). Treatment of [RuCl₂(PPh₃)₃] with two equivalents of dpam in CH₂Cl₂ gave a mixture of two products, from which trans-[RuCl₂(PPh₃) (dpam-As,As′)(dpam-As)] (4) was isolated by recrystallisation. The crystal structures of 1-4 are reported. Complexes 1-3 in CH₂Cl₂ undergo electrochemical oxidation to Ru(III), and the Ru(III) form of 2 undergoes isomerisation on the voltammetric timescale to the Ru(III) form of 3.     

Synthesis and characterisation of new molybdenum - oxo complexes containing diphenylphosphinylacetic acid and 2-(tert-butylsulphoxide)phenyldiphenylphosphine oxide as bidentate ligands

Reaction of the ligands diphenylphosphinylacetic acid Ph₂P(O)CH₂COOH (1) and 2-(tert-butylthio)phenyldiphenylphosphine oxide Ph₂P(O)C₆H₄^tBuS (2) with “MoO₂Cl₂”, resulted in two complexes MoO₂Cl₂Ph₂P(O)CH₂COOH (3) and MoO₂Cl₂Ph₂P(O)C₆H₄^tBuS(O) (4). Complexes 3 and 4 were isolated and analysed by ¹H NMR, ³¹P NMR and X-ray crystallography. Complex 3 crystallised with a molecule of the free ligand in a 1:1 ratio (3·1) and complex 4 crystallised with molecules of the solvent CH₂Cl₂ within the unit cell in a 2:1 ratio (4·0.5CH₂Cl₂). Tetrameric arrangements comprised of hydrogen bonds were observed in complexes 1 and 3. Complex 4 exhibited a seven-membered ring structure owing to the oxidation of the sulphide in 2 to sulphoxide and coordination of this ligand via the oxygen atoms to the molybdenum atom.     

Solid state coordination chemistry of molybdenum oxides with 1,2,3-triazole (Htrz): The crystal structures of [Cu(I)Cu(II)2(trz)2Mo4O13(OH)], [MoO3(Htrz)0.5] and [Cu(I)trz]

Hydrothermal chemistry was used to prepare the bimetallic organic-inorganic hybrid oxide [Cu(I)Cu(II)₂(trz)₂Mo₄O₁₃(OH)] · 6H₂O (1 · 6H₂O). The structure consists of chains linked through into a three-dimensional framework. The structures of the simple metal-triazole phases [MoO₃(Htrz)_0.5] (2) and [Cu(trz)] (3) are also reported. Compound 2 is two-dimensional, constructed from corner-sharing {MoO₅N} octahedra. Compound 3 consists of {Cu(trz)}_n chains linked through weak Cu?Cu contacts into a virtual layer.     

Four new copper(II) complexes with di-substituted s-triazine-based ligands

In this paper, two di-substituted triazine-based ligands, 6-chloro-N,N,N′N′-tetrakis-pyridin-2-ylmethyl-[1,3,5]triazine-2,4-diamine (L1), and 6-chloro-N,N′-bis-pyridin-2-ylmethyl-N,N′-bis-thiophen-2-ylmethyl-[1,3,5]triazine-2,4-diamine (L2), have been prepared. Reaction of CuCl₂·2H₂O and Cu(NO₃)₂·3H₂O with L1 and L2 results in the formation of [Cu₂Cl₄(L1)]·3MeOH (compound 1), [Cu₄(NO₃)₈(L1)₂]·2.07CH₂Cl₂·0.93MeOH (compound 2), [Cu₂Cl₄(L2)₂] (compound 3) and [Cu(NO₃)₂(L2)]·CH₂Cl₂ (compound 4), respectively, which have been fully characterized and determined by single-crystal X-ray crystallography, FT-IR, elemental analysis, thermogravimetric measurement and magnetic susceptibility. The dinuclear compound 1 shows strong π-π interactions between the neighboring pyridine rings. The nitrate-π (1,3,5-triazine ring) interaction with the distance of 2.755 Å in compound 2, is the closest contact reported so far. Compounds 3 and 4 are mononuclear copper(II) compounds, in which none of thiophene rings coordinates with copper(II) ion. In addition, the different orientations of two thiophene rings in compounds 3 and 4 lead to the π-π and CH₂Cl₂-π (thiophene ring) interactions in compound 4, but not in compound 3.     

Coordination polymers of Cu(II) and Cd(II) with bifunctional chelates of the type dipicolylamino-alkylcarboxylate, (NC5H4CH2)2N(CH2)nCO2H (n = 1, 2, 3 and 4)

A series of bifunctional chelates of the type dipicolylamino-alkylcarboxylate (NC₅H₄CH₂)₂N(CH₂)_nCO₂H (n = 1-4; HL¹-HL⁴, respectively) has been prepared. Reactions of the ligands in aqueous methanol/N,N-dimethylformamide with the appropriate Cu(II) salts yielded the compounds [CuL¹](NO₃)·H₂O (1·H₂O), [CuL²(H₂O)]BF₄·H₂O (2·H₂O), [Cu(HL³)(SO₄)]₂ (3) and [CuL⁴(NO₃)]·MeOH (4·MeOH). While compounds 1, 2 and 4 are one-dimensional, the detailed connectivities within the chains are quite distinct, depending on factors such as alkyl chain length and ligation of aqua ligands or anionic components. In contrast to 1, 2 and 4, the structure of 3 is molecular, a binuclear assembly of edge-sharing Cu(II) ‘4+2’ distorted octahedra. The Cd(II) species, [{CdL²}₂(SO₄)]·4H₂O (5·4H₂O), prepared from HL² and CdSO₄·nH₂O in aqueous methanol/N,N-dimethylformamide, is two-dimensional, with a network constructed from binuclear units of seven coordinate Cd(II), , linked through bridging SO₄²⁻ groups to produce an assembly of linked hexagonal rings [{CdL²}₂(SO₄)]₆.     

Supramolecular assemblies of [Mo3Se4Clx(H2O)9−x] with cucurbituril; complementarity control through the variation of x

From solutions of seleno bridged triangular cluster Mo₃Se₄(aq)⁴⁺ in HCl, crystalline adducts with cucurbituril (Cuc, C₃₆H₃₆N₂₄O₁₂) of different composition, depending on HCl concentration, were isolated. From 2 M HCl, a monosubstituted cationic cluster crystallizes as {[Mo₃Se₄Cl(H₂O)₈]₂(C₃₆H₃₆N₂₄O₁₂)}Cl₆·16H₂O (1). Increase in HCl concentration to 6 M gives a pentasubstituted anionic species, (H₃O)₂[Mo₃Se₄Cl₅(H₂O)₄]₂(C₃₆H₃₆N₂₄O₁₂)·15H₂O (2). The crystal structures of 1 and 2 were determined by X-ray crystallography. Each portal of Cuc in 1 is covered with cluster cations [Mo₃Se₄Cl(H₂O)₈]³⁺ like a ‘lid’ on a ‘barrel’. Six water molecules in the trans position to the core μ₂-Se form complementary hydrogen bonds with oxygen atoms of Cuc (O?O, 2.713-3.067 Å). In 2 the complementarity is lost and the main structure building factor is short Se?Se interactions (Se?Se, 2.96-3.43 Å) between two adjacent anionic clusters. Stereochemistry of halide substitution in the triangular clusters M₃Q₄ is analyzed.     

Synthesis, structure and reactivity of complexes containing [M(S2)2] fragments (M=Ru, Os; (S2)=1,2-benzenedithiolate (2−))

Subsequent addition of 1,2-benzenedithiol (S₂-H₂) and nBuLi to a solution of [Ru(NO)Cl₃ · xMeOH] in THF afforded exclusively the monomeric species NBu₄[Ru^II(NO)(S₂)₂] (1). Formation of dimeric (NBu₄)₂[Ru^II(NO)(S₂)₂]₂ (2) has been confirmed when the deprotonated ligand S₂-Li₂ was added to [Ru(NO)Cl₃ · xMeOH] and allowed to stir for 30 h. The monomer 1 undergoes aerial oxidation to give (NBu₄)₂[Ru^IV(S₂)₃] (3). The reaction between RuCl₃ · xH₂O and S₂-H₂ in the presence of NaOMe, afforded the dinulear Ru^III species (NMe₄)₂[Ru^III(S₂)₂]₂ (4). A modified method for the preparation of 1 is being employed to synthesize the osmium analogue NBu₄[Os(NO)(S₂)₂] (5) effectively. The solid state structures of 1, 2 and 3 were determined by X-ray crystal structure analysis. A comparison of relevant bond distance data suggests that 1,2-benzenedithiolate acts as an “innocent” ligand.     

Syntheses and crystal structures of cyano-bridged cluster-metal layered coordination polymers [Cu(dien)]3[W4Te4(CN)12] · 9H2O and [Ni(en)(NH3)]3[W4Se4(CN)12] · 7.5H2O

Two new tetrahedral tungsten cyanide cluster compounds, [Cu(dien)]₃[W₄Te₄(CN)₁₂] · 9H₂O (1) (dien=diethylenetriamine) and [Ni(en)(NH₃)]₃[W₄Se₄(CN)₁₂] · 7.5H₂O (2) (en=ethylenediamine), were synthesized by treating aqueous solutions of the saltlike cluster compound K₆[W₄Te₄(CN)₁₂] · 5H₂O/K₆[W₄Se₄(CN)₁₂] · 6H₂O with copper(II)/nickel(II) chloride in aqueous ammonia containing dien/en. The cyano-bridged layered coordination polymeric compounds were characterized by single-crystal X-ray diffraction analysis: monoclinic, space group P2₁ for 1; trigonal, space group for 2. Structures of 1 and 2 consist of infinite neutral layers of cluster components {W₄Te₄(CN)₁₂}/{W₄Se₄(CN)₁₂} connected, one another by {Cu(dien)} or {Ni(en)(NH₃)} fragments, respectively.     

Synthesis and characterization of Fe(III)(3-CH3O-qsal)2PF6 · nH2O (n = 0, 2)

Compounds Fe^III(3-CH₃O-qsal)₂PF₆ · nH₂O (n = 0, 2) (1, 1 · 2H₂O) were synthesized and characterized: the structure of 1 and the magnetic properties of both compounds were determined. Compound 1 · 2H₂O presents properties characteristic of high-spin Fe(III), while 1 presents properties of low-spin Fe(III) with an onset of a gradual spin crossover at ca. 300 K.     

A series of d transition metal coordination complexes: Structures and comparative study of surface electron behaviors (n = 9, 8, 7, 6, 5)

Ten transition metal coordination complexes [Cu₂(phen)(p-tpha)(μ-O)]_n1, [Cu(m-tpha)(imH)₂]_n2, [Ni(5-Haipa)₂(H₂O)₂]_n3, [Ni(phen)₂(H₂O)₂]·btc·[Ni(H₂O)₆]_0.5·9H₂O 4, [Co(2,5-pdc)(H₂O)₂]_n·nH₂O 5, [Co₂(2,5-pdc)₂(H₂O)₆]_n·2nH₂O 6, [Fe(2,5-Hpdc)₂(H₂O)₂]·H₂O 7, [Co(C₆H₄NO₂)₃]·H₂O 8, [Fe₂(μ₂-btec)(μ₂-H₂btec)(bipy)₂(H₂O)₂]_n9, [Mn(phen)(2,5-pdc)(H₂O)₂]·H₂O 10 (H₄btec = 1,2,4,5-benzenetetracarboxylic acid, phen = 1,10-phenanthroline, 2,5-H₂pdc = 2,5-pyridine-dicarboxylic acid, p-tpha = p-phthalic acid, m-tpha = m-phthalic acid, bipy = 2,2′-bipyridine, 5-H₂aipa = 5-aminoisophthalic acid, imH = imidazole, H₃btc = 1,3,5-benzenetricarboxylic acid) were synthesized through hydrothermal method. They were characterized by UV-Vis absorption spectra, single-crystal X-ray diffraction and surface photovoltage spectra (SPS). Structural analysis indicated that the complexes 1, 2, 3, 5, 6 and 9 were linked into infinite structures bridged by organic acid ligands. The other four complexes were molecular complexes and further connected to 2D or 3D structures by the hydrogen bonds. The SPS of complexes 1-10 indicate that there are positive response bands in the range of 300-800 nm showing different levels of photo-electric conversion properties. The intensity, position, shape and the number of the response bands in SPS are obviously different since the structure, species, valence, dⁿ electrons configuration and coordinated environment of the center metals are different. There are good relationships between SPS and UV-Vis spectra.     

Hydrogen-bonded copper(II) and nickel(II) complexes and coordination polymeric structures containing reduced Schiff base ligands

Complexes [Cu(HSas)(H₂O)] · 2H₂O (H₃Sas = N-(2-hydroxybenzyl)-l-aspartic acid) (1), [Cu(HMeSglu)(H₂O)] · 2H₂O (H₃MeSglu = (N-(2-hydroxy-5-methylbenzyl)-l-glutamic acid) (2), [Cu₂(Smet)₂] (H₂Smet = (N-(2-hydroxybenzyl)-l-methionine) (3), [Ni(HSas)(H₂O)] (4), [Ni₂(Smet)₂(H₂O)₂] (5), and [Ni(HSapg)₂] (H₂Sapg = (N-(2-hydroxybenzyl)-l-aspargine) (6) have been synthesized and characterized by chemical and spectroscopic methods. Structural determination by single crystal X-ray diffraction studies revealed 1D coordination polymeric structures in 2 and 4, and hydrogen-bonded network structure in 5 and 6. In contrast to previously reported coordination compounds with similar ligands, the phenol remains protonated and bonded to the metal ions in 2 and 4, and also probably in 1. However, the phenolic group is non-bonded in 6.