Novel metallophthalocyanines bearing 3-(p-chlorophenyl)-5-p-tolyl-4H-1,2,4-triazole bulky substituents by microwave irradiation

The synthesis of metallophthalocyanines [6–9; M = Ni(II), Zn(II), Co(II) and Cu(II)] with four 1,2,4-triazole units obtained from 4-{(4-chloro-2-fluorobenzyl)[3-(4-chlorophenyl)-5-(4-methylphenyl)-4H-1,2,4-triazol-4-yl]amino}phthalonitrile (5) in the presence of dimethylaminoethanol and the corresponding anhydrous metal salts is described. The thermal stabilities of the Pc compounds were determined by thermogravimetric analysis. The new compounds were characterized by a combination of IR, ¹H NMR, ¹³C NMR, UV–Vis, elemental analysis.     

Some transition metal ions complexes of tricine (Tn) and amino acids: pH-titration,synthesis and antimicrobial activity

Equilibrium studies have been carried out on complex formation of M(II) (M = Co(II), Cu(II) and Zn(II)) with tricine (Tn) and L = amino acids in aqueous solution, at 25 °C and ionic strength of I = 0.1 M (NaNO₃). The ternary complexes of amino acids are formed by simultaneous reactions. The concentration distribution of the complexes is evaluated. The solid complexes of [M(II)–Tn–Histidine (Hist)] have been synthesized and characterized by elemental analysis, infrared, magnetic and conductance measurements. The synthesized complexes have been screened for their antibacterial activities and the complexes show a significant antibacterial activity against four bacterial species: Staphylococcus aureus (Gram +ve), Streptococcus pyogenesr (Gram +ve), Serratia marcescens (Gram −ve) and Escherichia coli (Gram −ve). The activity increases by increasing the concentration of the complexes.     

Synthesis and spectroscopic characterization of new tetradentate Schiff base and its coordination compounds of NOON donor atoms and their antibacterial and antifungal activity

New Schiff base (H₂L) ligand is prepared via condensation of o-phthaldehyde and 2-aminobenzoic acid in 1:2 ratio. Metal complexes are prepared and characterized using elemental analyses, IR, solid reflectance, magnetic moment, molar conductance, ¹H NMR, ESR and thermal analysis (TGA). From the elemental analyses data, the complexes were proposed to have the general formulae [MCl(L)(H₂O)]·2H₂O (where M = Cr(III) and Fe(III)); [M(L)]·yH₂O (where M = Mn(II), Ni(II), Cu(II) and Zn(II), y = 1–2) and [M(L)(H₂O)_n]·yH₂O (where M = Co(II) (n = y = 2), Co(II) (n = y = 1), Ni(II) (n = 2, y = 1). The molar conductance data reveal that all the metal chelates were non-electrolytes. IR spectra show that H₂L is coordinated to the metal ions in a bi-negative tetradentate manner with NOON donor sites of the azomethine-N and carboxylate-O. The ¹H NMR spectral data indicate that the two carboxylate protons are also displaced during complexation. From the magnetic and solid reflectance spectra, it was found that the geometrical structure of these complexes are octahedral (Cr(III), Fe(III), Co(II) and Ni(II)), square planar (Cu(II)), trigonal bipyramidal (Co(II)) and tetrahedral (Mn(II), Ni(II) and Zn(II)). The thermal behaviour of these chelates showed that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the ligand molecule in the subsequent steps. The biological activity data show that the metal complexes to be more potent/antibacterial than the parent Shciff base ligand against one or more bacterial species.     

Spectroscopic and pH-metric studies of the complexation of 3-[2-(4-methylquinolin-2-yl)hydrazono]butan-2-one oxime compound

The electronic absorption spectra of the oximic quinolinyl hydrazone (MHQ; H₂L) and its Co(II) and Cu(II)-complexes have been studied in Britton–Rhobinson buffer solutions of varying pH's in 75% dioxane-water. The dissociation constant of the hydrazone (pK^H) as well as the stability constants (log K) of its chelates were determined spectrophotometrically and pH-metrically. The obtained data are in good agreement. Beer's law is valid in the ranges (0.64–6.99) and (2.36–6.48) μg/mL for Cu(II) and Co(II)-ions, respectively. On the other hand, the pK^H and log K were determined pH-metrically in 75% solvent-water; (solvent = dioxane, ethanol, methanol and isopropanol). The variation of pK^H or log K as a function of solvent parameters viz. 1/D, E_T, AN and π* was used to evaluate the dissociation and stability constants in the aqueous medium. Furthermore, the reaction of the oximic hydrazone (H₂L) with copper(II)-nitrate and chloride in addition to copper(I)-iodide afforded square planar mononuclear and binuclear complexes in which the oximic hydrazone showed three different modes of bonding. The obtained complexes reflect the strong bridging ability of the oximato group as well as its ambidentate and flexidentate characters.     

Synthesis and structures of cobalt(II) complexes of meso-tetraphenyloctaphyrin(1.0.1.0.1.0.1.0)s

Some meso-tetraphenyloctaphyrin(1.0.1.0.1.0.1.0)s and their Co(II) complexes were prepared and characterized on the basis of the ¹H NMR spectra and X-ray crystallography. These octaphyrins have a figure eight structure. The methyl and methylene protons directly bound to the bipyrrole β-position at the crossing point of the figure eight loop were very close to Co(II) and showed their ¹H NMR resonances in the range of 30–300 ppm. The insertion of Co(II) into the octaphyrin with mixed 2,2′-bipyrrole units of different substitution pattern induced transposition of the sterically more congested 2,2′-bipyrrole unit from the crossing point of the figure eight loop to the periphery.     

Synthesis and reactions of heterodinuclear organopalladium–cobalt complexes acting as copolymerization catalyst for aziridine and carbon monoxide

A series of heterodinuclear acylpalladium–cobalt complexes having a bidentate nitrogen ligand, L₂(RCO)Pd–Co(CO)₄ (L₂ = bpy, R = Me (5), Ph (6); L₂ = tmeda, R = Me (7), Ph (8); L₂ = phen, R = Me (9), Ph (10)) are prepared by metathetical reactions of PdRIL₂ with Na⁺[Co(CO)₄]⁻ followed by treatment with CO. These complexes are characterized by NMR and IR spectroscopies and elemental analyses, and the molecular structures of 6, 8, and 9 are determined by X-ray structure analysis. Geometry at Pd is essentially square planar and the Co atom is considered to have d¹⁰ tetrahedral structure, where cobalt(-I) anion coordinates to palladium(II) cation. Heterodinuclear organopalladium–cobalt complexes are shown to catalyze copolymerization of aziridines and CO under mild conditions. Reaction of (dppe)MePd–Co(CO)₄ (1) with aziridine gives a cationic (aziridine)palladium(II) complex with [Co(CO)₄]⁻ anion, [PdMe(aziridine)(dppe)]⁺[Co(CO)₄]⁻ (13).     

Synthesis,characterization and biological properties of Co(II), Ni(II), Cu(II) and Zn(II) complexes with an SNO functionalized ligand

Some new metal(II) complexes, ML₂[M = Co, Ni, Cu and Zn], of 2-acetylthiophene benzoylhydrazone ligand (HL) containing a trifunctional SNO-donor system have been synthesized and characterized on the basis of physicochemical data by elemental analysis, magnetic moment, molar conductance, thermogravimetric and spectroscopic (electronic, IR, ¹H NMR and ¹³C NMR) data. The ligand functions as monobasic SNO tridentates where the deprotonated enolic form is preferred in the coordination producing distorted octahedral complexes.     

Charge-transfer complexes of 4-nitrocatechol with some amino alcohols

Charge-transfer (CT) complexes formed from the reactions of 4-nitropyrocatechol (4-nCat) as an electron acceptor with four amino alcohols: 2-aminoethanol, 1-amino-2-propanol, 4-aminobutanol and N-(2-hydroxyethyl)-1,3-diaminopropane (NHEDAP) as electron donors, have been studied spectrophotometrically in H₂O and H₂O/EtOH at 20, 25, 30, 35 and 40 °C. The calculated values of the oscillator strength and transition moment confirm the formation of CT-complexes. The thermodynamic and spectroscopic parameters were also evaluated for the formation of CT-complexes. The equilibrium constants ranged from 9.00 to 2.20 l mol^?1 (M^?1). These interactions are exothermic and have relatively large standard enthalpy and entropy changes (ΔH values ranged from ?15.58 to ?3.10 kJ mol^?1; ΔS ranged from 26.81 to ?3.25 J K^?1 mol^?1). The solid CT-complexes have been synthesized and characterized by IR, NMR, mass spectrometry and thermal analysis. The photometric titration curves and other spectrometric data for the reactions indicated that the data obtained refer to the formation of 1:1 charge-transfer complex of [(4-nCat) (NHEDAP)] and 1:2 charge-transfer complexes of other amino alcohols [(4-nCat) (amino alcohol)₂]. The effect of alkali and alkaline earth metals on increasing the equilibrium constant of the CT-complexation was also investigated.     

Synthesis,spectroscopic, magnetic and thermal properties of bimetallic salts, [Ni(L)][MCl4] {where M = Co(II), Zn(II), Hg(II) and L = 3,7-bis(2-aminoethyl)-1,3,5,7-tetraazabicyclo(3.3.1)nonane}. X-ray structure of [Ni(L)][CoCl4]

New bimetallic complex salts corresponding to the formulation [Ni(L)][MCl₄] have been synthesized by the facile reaction between [Ni(L)](ClO₄)₂ and [MCl₂(PPh₃)₂] in high yields {where M = Co(II), Zn(II), Hg(II) and L = 3,7-bis(2-aminoethyl)-1,3,5,7-tetraazabicyclo(3.3.1)nonane}. The complexes were characterized by IR, electronic spectra, TGA/DSC, magnetic moment and conductivity measurements. The X-ray crystal structure for [Ni(L)][CoCl₄] clearly establishes the cationic–anionic interaction. It crystallizes in the space group P1 with unit cell dimensions a = 7.1740(15) Å, b = 8.1583(16) Å and c = 8.3102(16) Å. A square-planar geometry is evident for the [Ni(L)]²⁺ cation while the anion is found to be tetrahedral. A two-step thermolytic pattern is observed in the pyrolysis of the bimetallic complex salts.     

Combined experimental and computational study of W(II), Ru(II), Pt(IV) and Cu(I) amine and amido complexes using 15N NMR spectroscopy

Using 2D proton-coupled gHSQC pulse sequences in addition to 1D ¹⁵N NMR experiments of ¹⁵N labeled systems, ¹⁵N NMR chemical shifts of a range of transition metal amido and amine complexes were determined. Tungsten(II), ruthenium(II), platinum(IV) and copper(I) complexes with aniline and their anilido variants were studied and compared to free aniline, lithium anilido and anilinium tetrafluoroborate. Upon coordination of aniline to transition metals, upfield chemical shifts of 20–60 ppm were observed. Deprotonation of the amine complexes to form amido complexes resulted in downfield chemical shifts of 40–60 ppm for all of the complexes except for the tungsten d⁴ system. For the tungsten(II) complexes, the cationic aniline complex displayed a downfield shift of approximately 56 ppm relative to the neutral anilido complex. The change in chemical shift for amine to amido conversion is proposed to depend on the ability of the amido ligand to π-bond with the metal center, which influences the magnitude of the paramagnetic screening term.     

Synthesis,characterization and antibacterial activity of some new triphenyltin(IV) sulfanylcarboxylates: Crystal structure of [(SnPh3)2(p-mpspa)], [(SnPh3)2(cpa)] and [(SnPh3)2(tspa)(DMSO)]

Five new triphenyltin(IV) sulfanylcarboxylates of the general formula [(SnPh₃)₂L] (L = pspa, tspa, fspa, p-mpspa or cpa, where p = 3-(2-phenyl)-, t = 3-(2-thienyl)-, f = 3-(2-furyl)-, p-mp = 3-(4-methoxyphenyl)-, spa = 2-sulfanylpropenoato and cpa = 2-cyclopentilyden-2-sulfanylacetate) have been synthesized by reacting triphenyltin(IV) hydroxide with the corresponding acid in ethanol/acetone. The complexes have been characterized by elemental analysis and mass spectrometry and by vibrational and NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopies. In the case of [(SnPh₃)₂(p-mpspa)] and [(SnPh₃)₂(cpa)], X-ray structural studies showed that in both compounds each Sn atom is coordinated to three phenyl C atoms and to one S or O atom of the bridge ligand L. All five complexes are active against strains of Staphylococcus aureus, but are inactive against Escherichia coli and Pseudomonas aeruginosa. From a solution of [(SnPh₃)₂(tspa)] in DMSO-d₆ the new complex [(SnPh₃)₂(tspa)(DMSO)] was isolated. The single-crystal X-ray diffractometric study of this complex is also reported, showing that both Sn atoms are bridged by the tspa ligand, whereas the molecule of DMSO is coordinated to one of the tin atoms via the oxygen atom.     

Spin-crossover in cobalt(II) compounds containing terpyridine and its derivatives

In this review article we discuss the unique and novel magnetic properties for the cobalt(II) compounds with a variety of terpy derivatives including substituents at the 4-position. These are also compared with the unsubstituted terpy cobalt(II) complex. Since the first SCO cobalt(II) complex with terpy ligand was reported, this system has been widely studied. SCO cobalt(II) complexes possessing terpy or OH-terpy ligand reveal incomplete or gradual SCO behavior. The pyterpy-appended cobalt(II) complex shows SCO depending on the guest molecules involved. Cobalt(II) complexes with long-alkylated terpy ligands, [Co(Cn-terpy)₂](BF₄)₂ (n = 16, 14 and 12) have been synthesized and some were characterized by single crystal X-ray analysis. Furthermore, variable-temperature magnetic susceptibility indicated that the non-solvated compounds [Co(Cn-terpy)₂](BF₄)₂ (n = 16, 14 and 12) exhibit “reverse spin transition” phenomenon with wide thermal hysteresis around room temperature. In addition, the solvated compound [Co(C12-terpy)₂](BF₄)₂·EtOH·0.5H₂O shows “re-entrant SCO” behavior. The long alkyl chains in SCO cobalt(II) complexes can lead to novel physical properties resulting from a synergetic effect between SCO and response of the flexibility toward external stimuli.     

Organo-aluminum,zinc and magnesium derivatives of the imidotris(amido)phosphate Me3SiNP(NHtBu)3

Reactions of (^tBuHN)₃PNSiMe₃ (1) with the alkyl-metal reagents dimethylzinc, trimethylaluminum and di-n-butylmagnesium yield the monodeprotonated complexes [MeZn{(N^tBu)(NSiMe₃)P(NH^tBu)₂}] (2), [Me₂Al{(N^tBu)(NSiMe₃)P(NH^tBu)₂}] (3) and [Mg{(N^tBu)(NSiMe₃)P(NH^tBu)₂}₂] (4), respectively. Attempts to further deprotonate complex 2 with n-butyllithium or di-n-butylmagnesium result in nucleophilic displacement of the methylzinc fragment by lithium or magnesium. The two remaining amino protons of 3 are removed by reaction with di-n-butylmagnesium to give a heterobimetallic complex in which the coordination sphere of magnesium is completed by two molecules of THF (5 · 2THF) or one molecule of TMEDA (5 · TMEDA). Reaction of complex 3 with 1 equiv. of n-butyllithium followed by treatment of the product with di-n-butylmagnesium yields the complex {Me₂Al[(N^tBu)(NSiMe₃)P(N^tBu)₂]MgBu} Li · 4THF (6 · 4THF), the first example of a triply deprotonated complex of 1 containing three different metals. Reaction of complex 5 with iodine results in cleavage of an Al–Me group to give {MeIAl[(N^tBu)(NSiMe₃)P(N^tBu)₂Mg]} (7). Complexes 5 · 2THF, 5 · TMEDA, 6 · 4THF and 7 have been characterized in solution by multinuclear (¹H, ¹³C, ³¹P and ⁷Li) NMR spectroscopy, while the solid-state structures of 2, 4 and 5 · 2THF have been determined by X-ray crystallography.     

Synthesis and characterization of organophosphine/phosphite stabilized N-silver(I) succinimide: crystal structure of [(Ph3P)3 · AgNC4H4O2]

Six organophosphine/phosphite stabilized N-silver(I) succinimide complexes of the type L_n · AgNC₄H₄O₂ (L = PPh₃; n = 1, 2a; n = 2, 2b; n = 3, 2c; L = P(OEt)₃; n = 1, 2d; n = 2, 2e; n = 3, 2f) have been prepared by reacting [AgNC₄H₄O₂], which can be synthesized from succinimide and excessive Ag₂O in boiling water, with triphenylphosphine or triethylphosphite in dichloromethane under a nitrogen atmosphere. These complexes were obtained in high yields and characterized by elemental analysis, ¹H, ¹³C{H} NMR, IR spectroscopy and thermal analysis (TG and DSC). The molecular structure of 2c has been determined by X-ray single crystal analysis, in which the silver atom is in a distorted tetrahedral geometry.     

Apparent molar heat capacities and apparent molar volumes ofY2(SO4)3(aq),La2(SO4)3(aq),Pr2(SO4)3(aq),Nd2(SO4)3(aq),Eu2(SO4)3(aq),Dy2(SO4)3(aq),Ho2(SO4)3(aq), andLu2(SO4)3(aq)atT = 298.15 K andp = 0.1 MPa

The apparent molar heat capacities C_{p, φ} ^∘ and apparent molar volumes V_φ ^∘ of Y₂(SO₄)₃(aq), La₂(SO₄)₃(aq), Pr₂(SO₄)₃(aq), Nd₂(SO₄)₃(aq), Eu₂(SO₄)₃(aq), Dy₂(SO₄)₃(aq), Ho₂(SO₄)₃(aq), and Lu₂(SO₄)₃(aq) were measured at T =  298.15 K and p =  0.1 MPa with a Sodev (Picker) flow microcalorimeter and a Sodev vibrating-tube densimeter, respectively. These measurements extend from lower molalities of m =  (0.005 to 0.018) mol ·kg ^− 1to m =  (0.025 to 0.434) mol ·kg ^− 1, where the upper molality limits are slightly below those of the saturated solutions. There are no previously published apparent molar heat capacities for these systems, and only limited apparent molar volume information. Considerable amounts of the R SO₄ ⁺ (aq) and R(SO₄)₂ ⁻ (aq) complexes are present, where R denotes a rare-earth, which complicates the interpretation of these thermodynamic quantities. Values of the ionic molar heat capacities and ionic molar volumes of these complexes at infinite dilution are derived from the experimental information, but the calculations are necessarily quite approximate because of the need to estimate ionic activity coefficients and other thermodynamic quantities. Nevertheless, the derived standard ionic molar properties for the various R SO₄ ⁺ (aq) and R(SO₄)₂ ⁻ (aq) complexes are probably realistic approximations to the actual values. Comparisons indicate that V_φ ^∘ {RSO₄ ⁺ , aq, 298.15K}  =  − (6  ±  4)cm³· mol ^− 1and V_φ ^∘ {R(SO₄)₂ ⁻ , aq, 298.15K}  =  (35  ±  3)cm³· mol ^− 1, with no significant variation with rare-earth. In contrast, values of C_{p, φ} ^∘ { RSO₄ ⁺ , aq, 298.15K } generally increase with the atomic number of the rare-earth, whereas C_{p, φ} ^∘ { R(SO₄)₂ ⁻ , aq, 298.15K } shows a less regular trend, although its values are always positive and tend to be larger for the heavier than for the light rare earths.     

Novel metal-based pharmacologically dynamic agents of transition metal(II) complexes: Designing,synthesis, structural elucidation,DNA binding and photo-induced DNA cleavage activity

Novel Schiff base Cu(II), Ni(II), Co(II) and Zn(II) complexes have been designed and synthesized using the macrocyclic ligand derived from the condensation of diethylphthalate with Schiff base, obtained from benzene-1,2-diamine and 3-benzylidene-pentane-2,4-dione. The ligand and its complexes have been characterized by analytical and spectral techniques. DNA binding properties of these complexes have been investigated by UV–vis, viscosity measurements, cyclic voltammetric and differential pulse voltammogram studies. The intrinsic binding constants for Co(II), Ni(II), Cu(II) and Zn(II) complexes are 1.6 × 10⁶, 1.8 × 10⁶, 2.0 × 10⁶ and 1.5 × 10⁶ M^?1 respectively which are obtained from electronic absorption experiment. Control DNA cleavage experiments using pUC19 supercoiled (SC) DNA and minor groove binder (distamycin) suggest the major groove binding tendency for the synthesized complexes. In the presence of a reducing agent like 3-mercaptopropionic acid (MPA), the synthesized complexes show chemical nuclease activity under dark reaction condition. The complexes also show efficient photo-induced DNA cleavage activity on irradiation with a monochromatic UV light of 360 nm in the presence of inhibitors. Control experiments show inhibition of cleavage in the presence of singlet oxygen quencher like sodium azide and enhancement of cleavage in D₂O, suggesting the formation of singlet oxygen as a reactive species in a type-II process.     

Solid-state high-resolution NMR studies on spin fluctuation associated with valence tautomerism of metal–benzoquinone system: Cobalt complex in the stable and meta-stable phases

Equilibrium between low-spin [Co^III(SQ)(Cat)(N–N)] and high-spin [Co^II(SQ)₂(N–N)] redox isomers, where SQ is semiquinonate (charge: −1, spin: 1/2), Cat is catecholate (charge: −2, spin: 0) and N–N is chelating nitrogen donor ligand, respectively, is a representative valence tautomeric phenomenon. To elucidate independently the spin state of the cobalt ion and that of benzoquinone-derived ligands in the solid state, we measured ¹³C MAS NMR spectrum of 3,5-di-t-butyl-1,2-benzoquinone and ²H MAS NMR spectrum of deuterated 2,2′-bipyridine for [Co(3,5-di-t-butyl-1,2-benzoquinone)₂(2,2′-bipyridine)] · x(C₆H₅CH₃) and its deuterated analogue in a temperature range of 200–350 K. Irreversible change of an effective magnetic moment μ_eff of a virgin sample was observed around 370 K due to a partial loss of crystal solvent and a change of crystal structure, whereas the sample annealed at 390 K showed a crystal structure different from the reported one and a reversible change of μ_eff, which is ascribed to equilibrium between Co(III)-form (S = 1/2) and Co(II)-form (S = 3/2). Based on the shifts and the number of NMR peaks for the annealed sample, we concluded that (1) interconversion between redox isomers occurs faster than NMR time scale (>10⁴ s⁻¹) in the solid state, (2) intraconversion between SQ and Cat in Co(III)-form also occurs much faster than 5 × 10⁴ s⁻¹ even at 198 K and (3) electron spins on SQ ligands in Co(II)-form are quenched probably due to a strong antiferromagnetic coupling between the two SQ ligands. The enthalpy and the entropy of the interconversion were estimated to be 17 kJ/mol and 54 J/(K mol), respectively. For the virgin metastable phase, SQ and Cat were clearly distinguished by ¹³C MAS NMR spectrum. The solid-state high-resolution NMR spectrum is useful to detect independently the change of spin states of benzoquinone-derived radical and metal ion.     

Solution studies of tris(2-benzylaminoethyl)amine complexes of zinc(II) and copper(II): The catalytic hydrolysis of toxic organophosphate

Solution studies of the tetradentate ligand tris(2-benzylaminoethyl)amine, BzTren with both zinc(II) and copper(II) salts were investigated in aqueous methanol (33% v/v) by means of ¹H NMR, potentiometric, and UV-visible titrations as well as cyclic voltammetry. Subsequently, their zinc(II) and copper(II) complexes [BzTren-M(OH₂)]²⁺ 1 and 2 (M²⁺ = Zn²⁺ and Cu²⁺) were synthesized and fully characterized by using FT-IR spectroscopy, elemental analysis, and thermal analysis. Complexes 1 and 2 are investigated kinetically for the catalytic hydrolysis of the toxic organophosphate parathion at 50 °C in aqueous methanol (33%, v/v). The kinetic results indicate that copper(II) complex 2 is more active than zinc(II) complex 1, presumably a reflection of the effective electron-withdrawing as well as the greatest electrophilicity of copper(II) ion.     

Synthesis,structure and NMR characterization of a new monomeric aluminophosphate [dl-Co(en)3]2[Al(HPO4)2(H1.5PO4)2(H2PO4)2](H3PO4)4 containing four different types of monophosphates

A new zero-dimensional (0D) aluminophosphate monomer [dl-Co(en)₃]₂[Al(HPO₄)₂(H_1.5PO₄)₂(H₂PO₄)₂](H₃PO₄)₄ (designated AlPO-CJ38) with Al/P ratio of 1/6 has been solvothermally prepared by using racemic cobalt complex dl-Co(en)₃Cl₃ as the template. The Al atom is octahedrally linked to six P atoms via bridging oxygen atoms, forming a unique [Al(HPO₄)₂(H_1.5PO₄)₂(H₂PO₄)₂]^6? monomer. Notably, there exists intramolecular symmetrical O?H?O bonds, which results in pseudo-4-rings stabilized by the strong H-bonding interactions. The structure is also featured by the existence of four different types of monophosphates that have been confirmed by ³¹P NMR and ¹H NMR spectra. The crystal data are as follows: AlPO-CJ38, [dl-Co(en)₃]₂[Al(HPO₄)₂(H_1.5PO₄)₂(H₂PO₄)₂](H₃PO₄)₄, M = 1476.33, monoclinic, C2/c (No. 15), a = 36.028(7) Å, b = 8.9877(18) Å, c = 16.006(3) Å, β = 100.68(3)°, U = 5093.2(18) Å³_, Z = 4, R₁ = 0.0509 (I > 2σ(I)) and wR₂ = 0.1074 (all data). CCDC number 689491.     

Synthesis,structure and magnetic properties of 2-D and 3-D [cation]{M[Au(CN)2]3} (M = Ni, Co) coordination polymers

In order to study the templating effect of the cation and the resulting impact on the magnetic properties, reactions of M(II) salts with [cation][Au(CN)₂] were conducted, yielding a series of coordination polymers of the form [cation]{M[Au(CN)₂]₃} (cation = ⁿBu₄N⁺, PPN⁺ (bis(triphenylphosphoranylidene)ammonium); M = Ni(II) and Co(II)). The structures of ⁿBu₄N{M[Au(CN)₂]₃} and PPN{M[Au(CN)₂]₃} (M = Ni and Co) contain two distinct 3-D anionic frameworks of {M[Au(CN)₂]₃}⁻, hence the framework was sensitive to the cation, but not to the identity of the metal center. In ⁿBu₄N{M[Au(CN)₂]₃}, the metal centers are connected by [Au(CN)₂] units to form six 2-D (4, 4) rectangular grids that are fused through the M centers to yield a complex three-dimensional framework which accommodates the ⁿBu₄N⁺ cations. In PPN{M[Au(CN)₂]₃}, the framework adopts a simpler non-interpenetrated Prussian-blue-type pseudo-cubic array, with the PPN⁺ cations occupying each cavity; no reduction in dimensionality occurs despite the large cation size. In the presence of water, {Co(H₂O)₂[Au(CN)₂]₂} · ⁿBu₄N[Au(CN)₂] was obtained, a 2-D layered polymer that contains neutral sheets of {Co(H₂O)₂[Au(CN)₂]₂} which are separated by ⁿBu₄N[Au(CN)₂] layers; aurophilic interactions of 3.4250(13) Å and hydrogen-bonding connect the layers. The magnetic properties of all compounds were investigated by SQUID magnetometry. The Ni(II) polymers have similar magnetic behaviour, which are dominated by zero-field splitting with very weak antiferromagnetic interactions at low temperature (D ∼ 2–3 cm⁻¹, zJ < 1 cm⁻¹). The magnetic behaviour of all of the Co(II) polymers were found to be very similar, and dominated by single-ion effects (i.e. a large first-order orbital contribution). No significant magnetic coupling is observed in any of these coordination polymers, suggesting that the [Au(CN)₂] bridging unit behaves as a poor mediator of magnetic exchange in these high-dimensionality systems.