Two cadmium-thiocyanate coordination polymers with organic cations: Synthesis, crystal structures and luminescent properties

Two new inorganic-organic hybrid polymers [ClBzQl]₂[Cd(SCN)_3.5Br_0.5]·0.25H₂O (1) and [ClBzMePy][Cd(SCN)₃] (2) (ClBzQl = 1-(4′-Cl-benzyl)quinolinium cation and ClBzMePy = 1-(4′-Cl-benzyl)-2-methylpyridinium cation) have been synthesized and characterized by IR, UV, elemental analysis and X-ray crystallography. Crystal structure analyses show that two polymers belong to the monoclinic space group P2/n (1) and P2₁/c (2) with a = 18.548(2) Å, b = 9.526(1) Å, c = 20.689(2) Å, β = 94.008(1)°, V = 3646.6(5) Å³ for 1, and a = 11.195(2) Å, b = 16.415(3) Å, c = 10.751(2) Å, β = 102.930(3)°, V = 1925.7(7) Å³ for 2. The Cd atom exhibits a distorted octahedral coordination geometry for 1 and 2. For 1, a pair of 1,1-μ-SCN⁻ anions and a pair of 1,3-μ-SCN⁻ anions are alternately bridge adjacent Cd centers to form infinite polymeric chains. For 2, adjacent Cd atoms are linked by three 1,3-μ-SCN⁻ anions to form infinite [Cd(SCN)₃⁻]_∞ polymeric chains. The luminescent properties of the two polymers in the solid state at room temperature were investigated.     

Syntheses, structures, and magnetic properties of two new μ-alkoxo-μ-pyrazolato bridged dicopper(II) complexes

The syntheses, structures, and magnetic properties of two new μ-alkoxo-μ-pyrazolato heterobridged compounds, [Cu ^II₂(L¹-F)(μ-prz)] (1) and [Cu ^II₂(L¹-2OMe) (μ-prz)] · 0.5 CH₃CN (2) (prz=pyrazolato; H₂L¹-F=1,3-bis(3-fluorosalicylideneamino)-2-propanol; H₂L¹-2OMe=1,3-bis(4,6-dimethoxy salicylideneamino)-2-propanol) have been reported. Compound 1 crystallizes in triclinic space group with a=8.6392(10) Å, b=10.6431(9) Å, c=11.6809(13) Å, α=85.972(8)°, β=71.492(9)°, and γ=72.221(9)°, while the unit cell parameters of 2 are as follows: space group: monoclinic C2/c, a=28.2948(5) Å, b=7.3033(2) Å, c=26.3933(5) Å, and β=96.243(1)°. The variable-temperature magnetic susceptibility measurements reveal that the metal centers in both the compounds are antiferromagnetically coupled with J=−200 cm⁻¹ for 1 and J=−175 cm⁻¹ for 2. The magnetic behaviors have been explained on the basis of two opposing factors, complementarity and countercomplementarity of magnetic orbitals.     

Extended molecular networks based on Zn and Cd imparting N-substituted imidazole

Synthesis of complexes with the formulations [M(CPI)₂Cl₂] (M = Zn, 1; M = Cd, 4) and [M(CPI)₆](X)₂ (M = Zn, X = NO₃⁻, 2; X = ClO₄⁻, 3; M = Cd, X = NO₃⁻, 5; X = ClO₄⁻, 6) have been achieved from the reactions of MCl₂, M(NO₃)₂·xH₂O and M(ClO₄)₂·xH₂O (M = Zn, Cd) with 1-(4-cyanophenyl)-imidazole (CPI). Complexes 1-6 have been characterized by elemental analyses and spectral studies (IR, ¹H, ¹³C NMR, electronic absorption and emission). Molecular structures of 1, 2, 3 and 6 have been determined crystallographically. Weak interaction studies on the complexes revealed presence of various interesting motifs resulting from C-H···N, C-H···Cl and π-π stacking interactions. The complexes under study exhibit strong luminescence at ∼450 nm in DMSO at room temperature.     

Coordination versatility of 1,3-bis[3-(2-pyridyl)pyrazol-1-yl]propane: Co(II) and Ni(II) complexes

The ligand 1,3-bis[3-(2-pyridyl)pyrazol-1-yl]propane (L⁸) has afforded six-coordinate monomeric and dimeric complexes [(L⁸)Co^II(H₂O)₂][ClO₄]₂ (1), [(L⁸)Ni^II(MeCN)₂][BPh₄]₂ (2), [(L⁸)Ni^II(O₂CMe)][BPh₄] (3), and . The crystal structures of 1, 2 · MeCN, 3, and 4 revealed that the ligand L⁸ is flexible enough to expand its coordinating ability by fine-tuning the angle between the chelating fragments and hence folds around cobalt(II)/nickel(II) centers to act as a tetradentate chelate, allowing additional coordination by two trans-H₂O, cis-MeCN, and a bidentate acetate affording examples of distorted octahedral , , and coordination. The angles between the two CoN₂/NiN₂ planes span a wide range 23.539(1)° (1), 76.934(8)° (2), and 69.874(14)° (3). In contrast, complex 4 is a bis-μ-1,3-acetato-bridged (syn-anti coordination mode) dicobalt(II) complex [Co?Co separation: 4.797(8) Å] in which L⁸ provides terminal bidentate pyridylpyrazole coordination to each cobalt(II) center. To our knowledge, this report provides first examples of such a coordination versatility of L⁸. Absorption spectral studies (MeCN solution) have been done for all the complexes. Complexes 1-3 are uniformly high-spin. Temperature-dependent (2-300 K) magnetic studies on 4 reveal weak ferromagnetic exchange coupling between two cobalt(II) (S = 3/2) ions. The best-fit parameters obtained are: Δ (axial splitting parameter) = −765(5) cm⁻¹, λ (spin-orbit coupling) = −120(3) cm⁻¹, k (orbital reduction factor) = 0.93, and J (magnetic exchange coupling constant) = +1.60(2) m⁻¹.     

Structural, molecular mechanics, and DFT study of cadmium(II) in its crown ether complexes with axially coordinated ligands, and of the binding of thiocyanate to cadmium(II)

The role of relativistic effects (RE) in the structures of Cd(II) complexes with crown ethers, and the reason the ‘soft’ Cd(II) strongly prefers to bind to SCN⁻ through N, are considered. The synthesis and structures of [Cd(18-crown-6)(thiourea)₂] (ClO₄)₂.18-crown-6 (1) and [Cd(Cy₂-18-crown-6)(NCS)₂] (2) are reported. (18-crown-6 = 1,4,7,10,13,16-hexaoxacyclooctadecane; Cy₂-18-crown-6 = cis-anti-cis-2,5,8,15,18,21-hexaoxatricylo[20.4.0.0(9,14)]hexacosane). In 1 Cd is coordinated in the plane of the crown which has close to D_3d symmetry, with long Cd-O bonds averaging 2.688 Å. The two thiourea molecules form relatively short Cd-S bonds that average 2.468 Å, with an S-Cd-S angle of 164.30°. This structure conforms with the idea that Cd(II) can adopt a near-linear structure involving two covalently-bound donor atoms (the S-donors) with short Cd-S bonds, which resembles gas-phase structures for species such as CdCl₂. The structure of 2 is similar, with the two SCN⁻ ligands N-bonded to Cd, with short Cd-N bonds of 2.106 Å, and N-Cd-N angle of 180°. The crown in 2 forms long Cd-O bonds that average 2.698 Å. Molecular mechanics calculations suggest that a main reason Cd(II) prefers to bind to SCN⁻ through N is that when bound through S, the small Cd-S-C angle, which is typically close to 100°, brings the ligand into close contact with other ligands present, and causes steric destabilization. In contrast, the Cd-N-C angles for SCN⁻ coordinated through N are much larger, being 171.4° in 2, which keeps the SCN⁻ groups well clear of the crown ether. DFT (density functional theory) calculations are used to generate the structures of [Cd(18-crown-6)(H₂O)₂]²⁺ (3) and [Cd(18-crown-6)Cl₂] (4). In 3, the Cd(II) is bound to only three O-donors of the macrocycle, with Cd-O bonds averaging 2.465 Å. The coordinated waters form an O-Cd-O angle of 139.47°, with Cd-O bonds of 2.295 Å. In contrast, for 4, the Cd is placed centrally in the cavity of the D_3d symmetry crown, with long Cd-O bonds averaging 2.906 Å. The Cl groups form a Cl-Cd-Cl angle of 180°, with short Cd-Cl bonds of 2.412 Å. With ionically bound groups on the axial sites of[Cd(18-crown-6)X₂] complexes, such as with X = H₂O in 3, the Cd(II) does not adopt linear geometry involving the two X groups, with long Cd-O bonds to the O-donors of the macrocycle. With covalently-bound X = Cl in 4, short Cd-Cl bonds and a linear [Cl-Cd-Cl] unit results, with long Cd-O bonds to the crown ether.     

Two cyano-bridged heterotrinuclear complexes built from [(Tp)Fe(CN)3] (Tp = hydrotris(pyrazolyl)borate): synthesis, crystal structures and magnetic properties

Using an anionic precursor [(Tp)Fe^III(CN)₃]⁻ (1) as a building block, two cyano-bridged centrosymmetric heterotrinuclear complexes, (2) and (3) (en = ethylenediamine), have been synthesized and structurally characterized. In each complex, [TpFe(CN)₃]⁻ acts as a monodentate ligand toward a central [Mn(C₂H₅OH)₄]²⁺ or [Ni(en)₂]²⁺ core through one of its three cyanide groups, the other two cyanides remaining terminal. The intramolecular Fe-Mn and Fe-Ni distances are 5.2354(4) and 5.0669(11) Å, respectively. The magnetic properties of complexes 2 and 3 have been investigated in the temperature range of 2.0-300 K. A weak antiferromagnetic interaction between the Mn(II) and Fe(III) ions has been found in complex 2. The magnetic data of 2 can be fitted with the isotropic Hamiltonian: where J and J′ are the intramolecular exchange coupling parameters between adjacent and peripheral spin carriers, respectively. This leads to values of J = −1.37 cm⁻¹ and g = 2.05. The same fitting method is applied to complex 3 to give values of J = 1.2 cm⁻¹ and g = 2.25, showing that there is a ferromagnetic interaction between the Fe(III) and Ni(II) ions.     

The role of non-classical supramolecular interactions in the structures of 2-amino-4,6-dimethylpyridinium tetrahalocuprate (II) salts

The compounds [2-amino-4,6-dimethylpyridinium]₂CuCl₄ (1) and [2-amino-4,6-dimethylpyridinium]₂CuBr₄ (2) were prepared from acidic ethanolic media containing CuX₂ and [2-amino-4,6-dimethylpyridine] in the molar ratio 1:1. The compounds were characterized by IR and single-crystal X-ray diffraction and found to be isomorphous in the space group with V = 991.2(10) Å³ for (1) and 1059.26(12) Å³ for (2) . There is no significant difference in the non-classical N-H?X hydrogen bonding between (1) and (2). The anions show essentially the same extent of distortion from tetrahedral geometry with max./min. values for the X-Cu-X bond angles of 139.72(6)°/96.78(6)° for (1) and 139.43(4)°/96.64(3)° for (2). Each [CuX₄]²⁻ anion is hydrogen bonded nonsymmetrically to four cations. In this manner, ladder chains are formed that run along the b-axis, with planar cations falling parallel to the (2, 0, 1) plane. Weaker π-π interactions exist between cations from different chains with centroid to centroid distance of 4.07 Å in (1) and a long 4.594 Å in (2). The X-π electrostatic interactions are surprisingly stronger in (2) than in (1) with a Br to centroid of pyridinic ring distance of 3.890 Å compared with 3.996 Å for the chloride analogue.     

A trinuclear copper(II) complex with 2,5-pyridine-dicarboxylato bridges - [Cu3(2,5-pydc)2(Me5dien)2(H2O)2(BF4)2] · H2O: Synthesis, crystal structure and magnetic properties

A trinuclear copper(II) complex, [Cu₃(2,5-pydc)₂(Me₅dien)₂(BF₄)₂(H₂O)₂] · H₂O 1, has been constructed from 2,5-pyridine-dicarboxylato bridges (2,5-pydc²⁻) and N,N,N′,N″,N″-pentamethyl-diethylenetriamine (Me₅dien) acting as a blocking ligand. The copper ions, within the centrosymmetric trinuclear cations, are connected by two 2,5-pydc²⁻ bridges, with an intramolecular Cu···Cu separation of 8.432 Å. The central copper ion exhibits an elongated octahedral geometry, with semicoordinated ions, while the terminal ones are pentacoordinated (distorted square-pyramidal geometry). The cryomagnetic investigation of 1 reveals an antiferromagnetic coupling of the copper(II) ions (J = −5.9 cm⁻¹, H = −JS_Cu1S_Cu2 − JS_Cu2S_Cu1a).     

Hexa-coordinated aluminum and gallium cations derived from indazole

trans-Dichloro-tetrakis-(indazole)aluminum(III) tetrachloroaluminate(III) 1 and trans-dichloro-tetrakis-(indazole)gallium(III) tetrachlorogallate(III) 3 were obtained by the asymmetric cleavage of the chloride-bridged dimers [AlCl₃]₂ and [GaCl₃]₂ with two moles of indazole and characterized by NMR, X-ray diffraction, EA and IR. The synthesis of 3[1] was improved (yield 86%) using methylene chloride at room temperature. The addition of THF to a solution of 1/CH₂Cl₂ afforded in good yield complex 2 {[AlCl₂(IndH)₄]⁺[AlCl₄]⁻·4THF}. The crystal structures of these complexes are monoclinic in the space groups P2(1)/n (1), C2/c (2) and P2(1)/n (3). The unit cells of 1-3 contain ion pairs [ECl₂(IndH)₄]⁺ [ECl₄]⁻ (E = Al and Ga) with multiple hydrogen interactions (Cl?H 2.434-2.925 Å, O?H 1.984-2.665 Å, C?H 2.769-2.888 Å). The [ECl₂(IndH)₄]⁺ cations show hexa-coordinated octahedral aluminum and gallium atoms with two chlorine atoms in anti positions and four coplanar nitrogen atoms from the indazole ligands. The [ECl₄]⁻ anions have a tetrahedral coordination geometry around the central atom. In the lattice, the presence of THF molecules simplifies the weak interactions network in 2, so one anion interacts with two [MCl₂(Ind-H)₄]⁺ cations and two THF molecules through Cl?H intermolecular interactions (2.855-2.922 Å) and one [MCl₂(Ind-H)₄]⁺ cation interacts with two cations through ClL₄MCl?H interactions (2.922 Å). Whereas in 1 and 3, six anions interact through Cl?H intermolecular interactions (2.795-2.925 Å) with one [MCl₂(Ind-H)₄]⁺ cation and this latter interacts with other three [MCl₂(Ind-H)₄]⁺ cations through C?H interactions (2.769-2.888 Å). Additionally, every chlorine atom in the [MCl₂(Ind-H)₄]⁺ cationic moieties is bounded by NCH?ClM or NH?ClM intramolecular-tetrafurcated hydrogen bonds (2.434-2.907 Å).     

Squarato-metal(II) complexes. 1: Structural and magnetic characterization of squarato-bridged dinuclear nickel(II) and copper(II) complexes

A new series of dinuclear squarato-bridged nickel(II) and copper(II) complexes [Ni₂(2,3,2-tet)₂(μ_1,3-C₄O₄)(H₂O)₂](ClO₄)₂ (1), [Ni₂(aepn)₂(μ_1,3-C₄O₄)(H₂O)₂](ClO₄)₂ (2), [Cu₂(pmedien)₂(μ_1,3-C₄O₄)(H₂O)₂](ClO₄)₂.4H₂O (3) and [Cu₂(DPA)₂(μ_1,2-C₄O₄)(H₂O)₂](ClO₄)₂ (4) where is the dianion of 3,4-dihydroxycyclobut-3-en-1,2-dione (squaric acid), 2,3,2-tet = 1,4,8,11-tetraazaundecane, aepn = N-(2-aminoethyl)-1,3-propanediamine, pmedien = N,N,N′,N″,N″-pentamethyldiethylenetriamine and DPA = di(2-pyridylmethyl)amine were synthesized and structurally characterized by X-ray crystallography. The spectral and structural characterization as well as the magnetic behaviour of these complexes is reported. In this series, structures consist of the groups as counter ions and the bridging the two M(II) centers in a μ-1,3- (1-3) and in a μ-1,2-bis(monodentate) (4) bonding fashions. The coordination geometry around the Ni(II) ions in 1 and 2 is six-coordinate with distorted octahedral environment achieved by N atoms of the amines and by one or two oxygen atoms from coordinated water molecules, respectively. In the Cu(II) complexes 3 and 4, a distorted square pyramidal geometry is achieved by the three N-atoms of the aepn or DPA and by an oxygen atom from a coordinated water molecule. The electronic spectra of the complexes in aqueous solutions are in complete agreement with the assigned X-ray geometry around the M(II) centers. The complexes show weak antiferromagnetic coupling with ∣J∣ = 1.8-4.2 cm⁻¹ in the μ-1,3- bridged squarato compounds 1-3, and J = −16.1 cm⁻¹ in the corresponding μ-1,2- bridged squarato complex 4. The magnetic properties are discussed in relation to the structural data.     

Synthesis, crystal structure, magnetic properties and electrochemical behaviour of the mixed valence compound [Cu(CN)3Cu(C3H10N2)2]

The binuclear mixed valence copper(I/II) compound [Cu^I(CN)₃Cu^II(tn)₂] (1) (tn = propane-1,3-diamine) and its acetonitrile adduct [Cu^I(CN)₃Cu^II(tn)₂] · 2MeCN (2) have been synthesized. Complex 1 crystallizes triclinic, space group , a = 8.117(2) Å, b = 8.389(2) Å, c = 11.920(2) Å, α = 108.728(3)°, β = 100.024(3)°, γ = 104.888(4)°, Z = 2, and compound 2 monoclinic, space group P2₁/m, a = 8.752(2) Å, b = 13.243(3) Å, c = 9.549(2) Å, β = 114.678(4)°, Z = 2. In both crystal structures, the binuclear [Cu^I(CN)₃Cu^II(tn)₂] complex with slightly different bonding geometries is formed. One of the three nitrogen atoms of a Cu^I(CN)₃ moiety is coordinated to Cu(II) at the apex of a square-pyramid with two chelating ligands tn on its base. The shortest intramolecular Cu^II?Cu^II distance in 1 is 5.640(7) Å. The EPR behaviour of 1 has been investigated at room temperature and at 77 K. The magnetic properties were measured in the temperature range 1.8-300 K.     

Pyridine-2,6-dicarboxylate and perchlorate bridged hydrogen bonded 1D chains involving manganese(III)-cyclam moiety: synthesis, X-ray crystal structures and magnetic study

Two compounds H[Mn(cyclam)(pyridine-2,6-dicarboxylate)₂] · H₂O (1) and [Mn^III(cyclam)Cl₂]ClO₄ (2) (where cyclam=1,4,8,11-tetraazacyclotetradecane) have been synthesized and structurally characterized. The complex 1 crystallizes in the monoclinic space group P2(1)/c with a=11.4328(11), b=14.4275(14), c=8.5782(9) Å, , Z=2, R=0.0453. Complex 1 is octahedral in which [Mn(cyclam)]³⁺ unit occupies the basal plane having two pyridine-2,6-dicarboxylate anions in the axial positions. Molecular packing of the crystal is dominated by string of molecules along the b-axis. The strings are held together by extensive intermolecular hydrogen bonds involving N-H ? O, N-H ? N and O-H ? O which impart it an infinite 1D chain. Complex 2 on the other hand crystallizes in the space group P2₁2₁2₁ (No. 19) of the orthorhombic system. Mn(III) ions occupy the center of a distorted octahedron and two chloride ions occupy the axial positions. The packing diagram of 2 reveals that the complex is percholrate-bridged hydrogen bonded 1D chain along a-axis. Cyclic voltammogram of complex 1 shows a reduction wave at −0.25 V coupled to an oxidation wave at −0.05 V versus SCE in aqueous solution. The complex 2 is characterized by an irreversible reduction wave at −0.11 V versus SCE and is identical to that observed for [Mn^III(cyclam)Cl₂]Cl · 5H₂O. The magnetic measurements in the temperature range 1.9-300 K have been carried out for complex 1 which exhibits a very weak ferromagnetic interaction at low temperature. Complex 2 shows room temperature magnetic moment value of 4.92 BM consistent with the high spin d⁴ electronic configuration.     

Argentophilic interaction and anionic control of supramolecular structures in simple silver pyridine complexes

The synthesis and characterization of three simple 1:2 silver(I) pyridine adducts of different counter-anions, [Ag(py)₂]⁺ · X⁻ (X = ClO₄, 1; BF₄, 2; PF₆, 3), are reported. The structural studies for 1-3 reveal the presence of strong ligand-unsupported argentophilic interactions between [Ag(py)₂]⁺ ions, forming pairs of . The Ag?Ag contact distances are 2.96-3.00 Å. In 1 and 2, pairs of are further linked into 1-D infinite chains by a combined set of multiple Ag?Ag close contacts (3.34-3.37 Å), offset ‘head to head’ π-π stacking, and anion bridging interactions. Such combined set of interactions is anion-dependant with 1 and 2 containing anions of tetrahedral geometry and , affording essentially the same supramolecular architecture. Metal-anion interactions are crucial in organizing the 1-D chains into 3-D networks. The ES-MS studies of 1 and 2 provide positive evidence for the aggregation of silver(I) ions in solution. In contrast, for 3 with the counter-anion of octahedral , pairs of are organized into a 3-D network via a combined set of Ag?F contacts, C(H)?F hydrogen bonds, and ‘head to tail’ π-π stacking interactions. No extended 1-D polymeric chains of silver ions are present in 3.     

Homochiral metal-organic coordination networks from l-typtophan

Three homochiral metal-organic coordination networks [Co₂(l-Trp)₂(Py)₆] · Py · (ClO₄)₂ (1), [Ni(l-Trp)(Py)₃] · H₂O · ClO₄ (2) and [Co₂(l-Trp)(INT)₂(H₂O)₂(ClO₄)] (3), all containing natural amino acid l-HTrp (l-typtophan), were hydrothermally synthesized and structurally characterized. The compounds 1 and 2 crystallize in the orthorhombic space group C222₁, with a = 10.731(2) Å, b = 19.709(4) Å, c = 27.365(6) Å and Z = 4 for 1 and a = 10.710(10) Å, b = 20.088(18) Å, c = 27.63(3) Å and Z = 8 for 2, respectively. The compound 3 has the monoclinic space group P2₁, with a = 8.1934(14) Å, b = 13.209(2) Å, c = 12.464(2) Å, β = 104.107(3)° and Z = 2. Both 1 and 2 consist of 1D helical chains. Compound 3 is composed of 2D networks, which further assemble into a 3D supramolecular structure via weak interlayer interactions. The optically pure amino acid l-HTrp plays an important role leading to homochiral structures reported here.     

Synthesis of copper-zinc bimetallic imidazolate framework compounds and the structure of Cu(I)-containing Cu2Zn(N2C3H3)4

Copper(II)-zinc(II) bimetallic imidazolate metal-organic framework compounds of composition Cu_aZn_bIm_2(a + b) (Im = C₃H₃N₂), including Cu₂ZnIm₆ (1), were prepared in high yields from the metal oxides under mild aqueous conditions using a novel acid catalysis method. Mild acidic hydrothermal treatment of paramagnetic 1 (≥120 °C) gave diamagnetic Cu(I)-containing Cu₂ZnIm₄ (2) in high yield. The formation mechanism of 2 involves electron transfer from Im⁻ to Cu(II), with concomitant formation of the unusual cyclotriimidazole, C₉H₆N₆. Air-stable 2, characterized by single-crystal X-ray diffraction, crystallized in the tetragonal space group , with a = b = 10.9623(3), c = 6.3231(4) Å, α = β = γ = 90°, V = 759.86(6) Å³, and Z = 1.     

Synthesis and characterization of tetraphenylporphyrin manganese(III) complexes of phenylcyanamide ligands

Several complexes of TPPMn-L, where TPP is the dianion of tetraphenylporphyrin and L is monoanion of 4-methylphenylcyanamide (4-Mepcyd) (1), 2,4-dimethylphenylcyanamide (2,4-Me₂pcyd) (2), 3,5-dimethylphenylcyanamide (3,5-Me₂pcyd) (3), 4-methoxyphenylcyanamide (4-MeOpcyd) (4), phenylcyanamide (pcyd) (5), 2-chlorophenylcyanamide (2-Clpcyd) (6), 2,5-dichlorophenylcyanamide (2,5-Cl₂pcyd) (7), 2,6-dichlorophenylcyanamide (2,6-Cl₂pcyd) (8), 4-bromophenylcyanamide (4-Brpcyd) (9), and 2,3,4,5-tetrachlorophenylcyanamide (2,3,4,5-Cl₄pcyd) (10), have been prepared from the reaction of TPPMnCl and thallium salt of related phenylcyanamide. Each of the complexes has been characterized by IR, UV-Vis and ¹H NMR spectroscopies.4-Methylphenylcyanamidotetraphenylporphyrin manganese(III) crystallized with one molecule of solvent CHCl₃ in the triclinic crystal system and space group with the following unit cell parameters of: a = 11.596(6) Å; b = 11.768(9) Å; c = 17.81(2) Å; and α, β, γ are 88.91(9)°, 88.16(7)°, 67.90(5)°, respectively; V = 2251(3) Å³; Z = 2. A total of 4234 reflections with I > 2σ(I) were used to refine the structure to R = 0.0680 and R_w = 0.2297. The Mn(III) shows slightly distorted square pyramidal coordination with the 4-methylphenylcyanamide in the axial position, coordinated from nitrile nitrogen. The reduction of each of the TPPMn-L complexes was also examined in dichloromethane and spectroelectrochemical behavior of (1) was investigated and compared to TPPMnCl.     

Copper(II) complexes derived from tripodal tris[(2-ethyl-(1-pyrazolyl)]amine

Three mono-nuclear copper(II) complexes [Cu(tepza)X]ClO₄ (X = Cl, 1; X = NCS, 2; X = dca, 3) and two dinuclear bridging complexes [Cu₂(tepza)₂(μ-C₄O₄)](ClO₄)₂·H₂O(4) and [Cu₂(tepza)₂(μ-C₅O₅)](ClO₄)₂(5) where tepza = tris[2-ethyl(1-pyrazolyl)]amine, dca = dicyanamide, C₄O₄²⁻ = 3,4-dihydroxycyclobut-3-ene-1,2-dionate (squarate dianion) and C₅O₅²⁻ = 4,5-dihydroxycyclopent-4-ene-1,2,3-trionate (croconate dianion) were synthesized and structurally characterized by IR and UV-Vis spectroscopy as well as by single X-ray crystallography. In the solid state, the geometry of copper(II) centers in these complexes are as follows: close to SP in 2, distorted TBP in 3, predominant SP in 4, and distorted octahedral in 5, whereas in solution distorted SP geometry was generally found. The squarato and the croconato dianions in complexes 4 and 5 are bridging the two copper(II) centers in cis-bis-monodentate and bis-bidentate bonding modes, respectively. Magnetic susceptibility measurements at variable temperatures (2-300 K) reveal the weak antiferromagnetic coupling in the two bridging dinuclear complexes 4 (J = −24.9 cm⁻¹) and 5 (J = −3.1 cm⁻¹).     

Discrete and 1D coordination polymeric chloro-bridged copper(II) dimers exhibiting ferro- and antiferromagnetic exchange coupling: Magneto-structural correlations and non-covalent interactions

The synthesis and characterization of two 1D coordination polymers [Cu₂(MHL)Cl₂][ClO₄]₂ · CH₃CN · THF (2 · CH₃CN · THF) and [Cu₂(MPyPz)Cl₂][ClO₄]₂ · CH₃CN (3 · CH₃CN), having repetitive units, of m-xylyl-based ligands with terminal tridentate (2-pyridyl)alkylamine (MHL = α,α′-bis[N-(2-pyridylethyl)-N-(2-pyridylmethyl)amino]-m-xylene) and (2-pyridyl)alkylamine/pyrazole (MPyPz = α,α′-bis[N-(2-pyridylethyl)-N-(pyrazol-1-ylmethyl)amino]-m-xylene) coordination have been accomplished. X-ray crystallographic studies reveal that the copper(II) centers in the recently reported dichloro-bridged discrete complex [{Cu(MeL)Cl}₂][ClO₄]₂ (1) of a tridentate (2-pyridyl)alkylamine ligand [MeL = methyl[2-(2-pyridyl)ethyl](2-pyridylmethyl)amine], 2 · CH₃CN · THF, and 3 · CH₃CN have distorted square-pyramidal geometry, sharing a base-to-apex edge with parallel basal planes. Variable-temperature susceptibility measurements in the range of 2-300 K reveal antiferromagnetic for 1 [J (singlet-triplet energy gap) = −3.89 cm⁻¹] and 2 · CH₃CN · THF (J = −1.84 cm⁻¹), and ferromagnetic for 3 · CH₃CN (J = +6.27 cm⁻¹) coupling. The complexes provide useful information for the magneto-structural correlations.     

Synthesis and single crystal structural investigations on quaternary salts of tellurated alkylamine derivatives

Tellurated alkylamine derivatives , , and have been synthesized by reacting appropriate organic halides with the nucleophile 4-CH₃OC₆H₄Te⁻ or Te²⁻ generated in situ by borohydride reduction of (4-CH₃OC₆H₄Te)₂ or Te powder followed by reaction with HCl of appropriate concentration. The zwitterionic species was generated when single crystals of 2 were grown in methanol at 0 °C. Complexes 1-4 exhibit characteristic ¹H NMR spectra. The single crystal structures of 1-4 and 2a have been determined. In the crystals of 1, C-H?π distances have been found to be 3.31(7)-3.59(5) Å. In both 2 and 2a, weak Te?Cl interactions (3.54(2) -3.62(2) Å) are observed. The C-H?π distance in the crystal of 2 is 3.19(0) Å. In 2a and 3, water hydrogen bonds connect the water molecules with the end groups from different molecules. In the case of 3, Te?Cl weak interactions involving the Cl⁻ ions connect together two such chains. The geometry of Te in 1 is V shaped. In 2 and 3 it is pseudo trigonal bipyramidal, and in 2a, it is square pyramidal. However, in the latter case it becomes distorted octahedral due to weak Te?Cl secondary interactions. The geometry about Te in 4 is distorted octahedral due to weak Te?Cl interactions involving Cl⁻ ions. However, there are no intermolecular Te?Cl interactions.     

A novel tetranuclear hydrogenphosphate-bridged Cu(II) cluster. Synthesis, structure, spectroscopy and magnetism of [Cu4(dpyam)4(μ4,η-HPO4)2(μ-X)2]X2(H2O)6 (X = Cl, Br)

Two novel tetranuclear compounds with an unprecedented mode of a hydrogenphosphato bridge, [Cu₄(dpyam)₄(μ₄,η³-HPO₄)₂(μ-X)₂]²⁺ (in which dpyam = di-2-pyridylamine and X = Cl (1), Br (2)) have been synthesised and characterised structurally and magnetically. The Cu(II) ions in the structures each display a square-pyramidal geometry, with two tridentate hydrogenphosphato groups bridging four copper atoms in a μ₄,η³ coordination mode which is rarely found in hydrogenphosphate metal compounds. Each (different) pair of Cu(II) ions is additionally bridged by halide ions, with relatively long Cu-X distances (2.551(3)-2.604(3) Å for 1 and 2.707(1)-2.766(2) Å for 2) and subsequently also a small Cu-X-Cu angle (65.7(1)° and 65.1(1)° for 1 and 61.6(1)° and 62.4(1) for 2) and a large Cu-X-Cu angle (95.5(1)° and 96.5(1)° for 1 and 91.1(1)° and 92.6(1)° for 2). Cu?Cu distances in the tetranuclear units varies from 2.802(3) to 5.232(3) Å for 1 and from 2.834(1) to5.233(1) Å in 2. The lattice structures are stabilised by extensive intermolecular hydrogen bonds. The magnetic susceptibility measurements down to 5 K revealed a weak ferromagnetic interaction between the outer pairs of Cu(II) ions which vary from 22 to 46 cm⁻¹ in 1 and 12 to 33 cm⁻¹ in 2 and a moderately strong antiferromagnetic interaction between the inner Cu(II) ions of −79 cm⁻¹ in 1 and −83 cm⁻¹ in 2, via the Cu-O-P-O-Cu pathway.