Synthesis, crystal structure and vibrational spectroscopy of a novel mixed ligands Ni(II) pentaborate: [Ni(C4H10N2)(C2H8N2)2][B5O6(OH)4]2

A novel organic-inorganic hybrid pentaborate [Ni(C₄H₁₀N₂)(C₂H₈N₂)₂][B₅O₆(OH)₄]₂ has been synthesized by hydrothermal reaction and characterized by FT-IR, Raman spectroscopy, elemental analyses and DTA-TGA. Its crystal structure was determined from single crystal X-ray diffraction. The structure consists of isolated polyborate anion [B₅O₆(OH)₄]⁻ and nickel complex cation of [Ni(C₄H₁₀N₂)(C₂H₈N₂)₂]²⁺, in which the two kinds of ligands come from the decomposition of triethylenetriamine material. The [B₅O₆(OH)₄]⁻ units are connected to one another through hydrogen bonds, forming a three-dimensional framework with large channel along the a and c axes, in which the templating [Ni(C₄H₁₀N₂)(C₂H₈N₂)₂]²⁺ cations are located. The assignments of the record FT-IR absorption frequencies and Raman shifts were given.     

An aluminoborate cluster [AlB12O14(OH)12]: Synthesis and structure of [C5H6N][AlB12O14(OH)12]

A new aluminoborate, [C₅H₆N][AlB₁₂O₁₄(OH)₁₂], has been hydrothermally synthesized at 200 °C. The single-crystal diffraction study reveals that it crystallizes in space group C2/c. It consists of aluminoborate clusters [AlB₁₂O₁₄(OH)₁₂]⁻ and counterions [C₅H₆N]⁺. The aluminoborate cluster contains an Al(OH)₆ octahedron as a core that is capped by two raft-like polyborate units [B₆O₇(OH)₆]. These clusters are further interlinked by extensive hydrogen bonding to form a three-dimensional (3D) network, containing large channels along the b-axis, in which the [C₅H₆N]⁺ cations are located.     

Rb2[B12(OH)12]·2H2O and Rb2[B12(OH)12]·2H2O2: Hydrate and perhydrolate of rubidium dodecahydroxo-closo-dodecaborate

The orthorhombically crystallizing salts Rb₂[B₁₂(OH)₁₂]·2H₂O (a = 1576.81(9), b = 813.08(5), c = 1245.32(7) pm) and Rb₂[B₁₂(OH)₁₂]·2H₂O₂ (a = 1616.54(9), b = 814.29(5), c = 1260.12(7) pm) could be prepared from Rb₂[B₁₂H₁₂] and hydrogen peroxide. Both crystal structures were determined by X-ray single crystal diffraction and refined in the space group Cmce. They are not isostructural to the other compounds containing icosahedral dodecahydroxo-closo-dodecaborate dianions [B₁₂(OH)₁₂]²⁻ and potassium, rubidium or cesium cations already known to literature, but both title compounds crystallize quasi-isotypically exhibiting Rb⁺ cations in 10-fold oxygen coordination. The hydrogen peroxide adduct (Rb₂[B₁₂(OH)₁₂]·2H₂O₂) is explosive on shock and heat, while the hydrate (Rb₂[B₁₂(OH)₁₂]·2H₂O) is not.     

Preparation and structure of [Ru2(O2CMe)4]2[Fe(CN)5NO] and magnetically ordered Hx[Ru2(O2CMe)4]3−x[Cr(CN)5NO] possessing interpenetrating lattices

Reaction of [Ru₂(O₂CMe)₄]Cl with K₃[Cr(CN)₅NO] in water forms H_x[Ru^II/III₂(O₂CMe)₄]_3−x-[Cr(CN)₅NO]·zH₂O (x = 0.2) that magnetically orders at 4.0 K and possesses an interpenetrating body centered cubic [a = 13.2509(2) Å] structure with random locations of the bridging nitrosyl ligands, and x/3 vacant cation sites. Similarly, the aqueous reaction of [Ru₂(O₂CMe)₄]Cl with Na₂[Fe(CN)₅NO] forms paramagnetic [Ru₂(O₂CMe)₄]₂[Fe(CN)₅NO]·H₂O, which has a similar tetragonal interpenetrating structure [a = 13.0186(1) Å, c = 13.0699(2) Å] where the NO ligands are presumably nonbridging and 1/3 of the expected cation sites are unoccupied. The presence of uncoordinated NO sites in addition to missing neighboring [Ru₂(O₂CMe)₄]⁺ units, results in significant vacancies (or holes) in the lattice.     

Water replacement on the decaaqua-di-rhodium(II) cation; synthesis of superoxo and peroxo rhodium(III) complexes with N-donor ligands

The decaaqua-di-rhodium(II) cation has been found to be an interesting starting material in the preparation of dioxygen complexes with different N-donor ligands. Treatment of aqueous HClO₄ solution of [Rh₂(H₂O)₁₀]⁴⁺ with NH₄OH/NH₃, py and/or en results in water exchange and the formation of corresponding [Rh₂^II(H₂O)_10−m(base)_n(OH)_m]^(4−m)+ derivatives. Reaction of the latter with dioxygen afforded superoxo and/or peroxo complexes, depending on reaction conditions: [Rh₂^III(O₂ ⁻)(NH₃)₈(OH)₂](ClO₄)₃ (1), [Rh₂^III(O₂ ⁻)(NH₃)₈(OH)(H₂O)](ClO₄)₄ (2), [Rh₂^III(O₂ ²⁻)(NH₃)₁₀](ClO₄)₄ · 6H₂O (3), [Rh₂^III(O₂ ⁻)(py)₈(H₂O)₂](ClO₄)₅ (4), [Rh₂^III(O₂ ²⁻)(en)₄(H₂O)₂](ClO₄)₄ (5) and [Rh₂^III(O₂ ⁻)(en)₄(H₂O)₂](ClO₄)₅ (6). All the obtained complexes were characterized by elemental analysis, mass spectrometry, UV-Vis, IR and ESR spectroscopies and magnetic measurements.     

Catalytic effect of cis-diammineplatinum α-pyrrolidone tan adsorbed on a platinum electrode in electrochemical oxidation of water into molecular oxygen

Cyclic voltammograms of cis-diammineplatinum α-pyrrolidone-blue and -tan, [Pt₄(NH₃)₈(C₄H₆NO)₄]ⁿ⁺ (n = 5 and 6, respectively) show for either complex only one redox peak at 0.53 V (average potential of the anodic and cathodic peak potentials). Coulometry and UVVis spectra of bulk- electrolyzed solution indicated that the redox peak corresponds to the reaction [Pt₄(NH₃)₈(C₄H₆NO)₄]⁸⁺ + 4e ⇄ 2[Pt₂(NH₃)₄(C₄H₆NO)₂]²⁺. When cyclic voltammetry is carried out in a solution of [Pt₄(NH₃)₈(C₄H₆NO)₄]⁶⁺ or a platinum electrode adsorbed with [Pt₄(NH₃)₈(C₄H₆NO)₄]⁶⁺ is used in the presence of oxidizing agent in the solution, O₂ gas generates from the electrode surface with large catalytic cathodic current at potentials below ca. 0.8 V. The O₂ gas was confirmed to generate from water by GC-MS analysis. This abnormal O₂ generation phenomenon is explained with cyclic reactions of chemical surface oxide formation on the electrode by the oxidizing agent and electrochemical reduction of the surface oxide. Oxygen gas generates from the reaction of [Pt₄(NH₃)₈(C₄H₆NO)₄]⁸⁺ or [Pt₄(NH₃)₈(C₄H₆NO)₄]⁶⁺ with OH⁻ produced in the course of the electrochemical reduction of the electrode surface oxide. The ability of [Pt₄(NH₃)₈(C₄H₆NO)₄]⁸⁺ and [Pt₄(NH₃)₈(C₄H₆NO)₄]⁶⁺ to oxidize OH⁻ into O₂ has been reported previously.     

Dinuclear metal phosphonates and -phosphates

The reaction of Cu(II) or Cd(II) salts with 2,4,6-iPr₃C₆H₂PO₃H₂, 2,4,6-iPr₃C₆H₂CH₂PO₃H₂ or 2,6-iPr₂C₆H₃OPO₃H₂ in the presence of strong chelating nitrogen ligands such as 2,2′-bipyridine (bpy), 1,10-phenanthroline (phen), 2-pyridylpyrazole (pypz) or 3,5-dimethyl pyrazole (dmpz) as the ancillary ligands afforded dinuclear copper or cadmium complexes [Cu₂(2,4,6-iPr₃C₆H₂PO₃H)₄(bpy)₂] (4), [Cu₂(2,6-iPr₂C₆H₃OPO₃H)₂(bpy)₂(OAc)₂(CH₃OH)₂]·(CH₃OH) (5), [Cd₂(2,6-iPr₂C₆H₃OPO₃H)₄ (bpy)₂(CH₃OH)₂]·2(CH₃OH) (6), [Cd₂(2,6-iPr₂C₆H₃OPO₃H)₄(phen)₂] (7), [Cu₂(2,6-iPr₂C₆H₃OPO₃H)₂(PyPz)₂(CH₃OH)₂] (8) and [Cu₂(2,4,6-iPr₃C₆H₂CH₂PO₃H)₂(DMPz)₂Cl₂]·(CH₃OH) (9) The molecular structures of 4-7 are grossly similar. The common structural features in these complexes are that the two metal centers are bridged by two bidentate [RPO₂(OH)]⁻ ligands generating a central eight-membered ring. Each of the metal centers also contains a chelating nitrogen ligand and a monodentate phosphonate or a phosphate ligand. In 5 and 6 other terminal ancillary ligands are also present. In compound 8, each of the two copper centers contains a monodentate [RPO₂(OH)]⁻ ligand along with a molecule of methanol. The two coppers are bridged by two monoanionic pyridylpyrazole ligands. The molecular structure of 9 is similar to that of 4-7. However, in 9 each of the two copper centers contain only terminal monodentate ligands in the form of two chlorides and a pyrazole. Magnetic studies on all of these copper complexes reveal an anti-ferromagnetic behavior at low temperatures. In addition, these complexes were found to be artificial nucleases and can convert supercoiled pBR322 DNA form I into nick form II in 1 min in the presence of an external oxidant through a hydrolytic and/or an oxidative pathway.     

Interactions of tertiary phosphines with p-benzoquinones; X-ray structures of [HO(CH2)3]3PC6H2(O)(OH)(MeO) and Ph3PC6H3(O)(OH)

Phosphonium zwitterions of a known type were obtained in high yield via a 1:1 reaction of p-benzoquinone or methoxy-p-benzoquinone with the tertiary phosphines R₃P [R = (CH₂)₃OH, Ph, Et, Me] and Ph₂MeP, in acetone or benzene at room temperature. In all cases, attack of the P-atom occurs at a C-atom rather than at an O-atom. The products were characterized to various degrees by elemental analysis, ³¹P{¹H}, ¹H and ¹³C NMR spectroscopies, and mass spectrometry, and two of the zwitterions, the new [HO(CH₂)₃]₃P⁺C₆H₂(O⁻)(OH)(MeO) and the known Ph₃P⁺C₆H₃(O⁻)(OH), were structurally characterized by X-ray analysis. The PEt₃ reaction also produces small amounts of the ‘dimeric’, μ-oxo co-product Et₃P⁺C₆H₂(O⁻)(OH)-O-C₆H₃(O⁻)P⁺Et₃ that is tentatively characterized by 1D- and 2D-NMR data. 2,5-Di-tert-butyl- and 2,3,5,6-tetramethyl-p-benzoquinone do not react with [HO(CH₂)₃]₃P under the conditions noted above. Heating D₂O solutions of the water-soluble zwitterions R₃P⁺C₆H₃(O⁻)(OH) [R = (CH₂)₃OH, Et] at 90 °C for 72 h leads to complete H/D exchange of the H-atom in the position ortho to the phosphonium center.     

SS Bond-activation of diorganyl disulfide by anionic [Mn(CO)5]: crystal structures of [Mn(SC5H4NO)3] and [(CO)3Mn(μ-SR)3Co(μ-SR)3Mn(CO)3] (R=C6H4NHCOPh)

The SS bond-activation of diorganyl disulfide by the anionic metal carbonyl fragment [Mn(CO)₅]⁻ gives rise to an extensive chemistry. Oxidative decarbonylation addition of 2,2′-dithiobis(pyridine-N-oxide) to [Mn(CO)₅]⁻, followed by chelation and metal-center oxidation, led to the formation of [Mn^II(SC₅H₄NO)₃]⁻ (1). The effective magnetic moment in solid state by SQUID magnetometer was 5.88 μ_B for complex 1, which is consistent with the Mn^II having a high-spin d⁵ electronic configuration in an octahedral ligand field. The average Mn(II)S, SC and NO bond lengths of 2.581(1), 1.692(4) and 1.326(4) Å, respectively, indicate that the negative charge of the bidentate 1-oxo-2-thiopyridinato [SC₅H₄NO]⁻ ligand in complex 1 is mainly localized on the oxygen atom. The results are consistent with thiolate-donor [SC₅H₄NO]⁻ stabilization of the lower oxidation state of manganese (Mn(I)), while the O,S-chelating [SC₅H₄NO]⁻ ligand enhances the stability of manganese in the higher oxidation state (Mn(II)). Activation of SS bond as well as OH bond of 2,2′-dithiosalicylic acid by [Mn(CO)₅]⁻ yielded [(CO)₃Mn(μ-SC₆H₄C(O)O)₂Mn(CO)₃]²⁻ (4). Oxidative addition of bis(o-benzamidophenyl) disulfide to [Mn(CO)₅]⁻ resulted in the formation of cis-[Mn(CO)₄(SR)₂]⁻ (R=C₆H₄NHCOPh) which was employed as a chelating metallo ligand to synthesize heterotrinuclear [(CO)₃Mn(μ-SR)₃Co(μ-SR)₃Mn(CO)₃]⁻ (8) possessing a homoleptic hexathiolatocobalt(III) core.     

Synthesis, crystal structure and luminescent behaviour of coordination complexes of copper with bi- and tridentate amines and phosphonic acids

The synthesis and crystal structure of four new copper(I) and copper(II) supramolecular amine, and amine phosphonate, complexes is reported. Reaction of copper(I) with 2-,9-dimethyl-1-10-phenanthroline (dmp) produced a stable 4-coordinate Cu(I) species, [Cu^(I)(dmp)₂]Cl · MeOH · 5H₂O (2), i.e., the increased steric hindrance in the ‘bite’ area of dmp did not prevent interaction with the metal and provided protection against oxidation which was not possible for the phen analogue [R. Clarke, K. Latham, C. Rix, M. Hobday, J. White, CrystEngCommun. 7(3) (2005), 28-36]. Subsequent addition of phenylphosphonic acid to (2) produced two structures from alternative synthetic routes. An ‘in situ’ process yielded red block Cu(I) crystals, [Cu^(I)(dmp)₂] · [C₆H₅PO₃H₂ · C₆H₅PO₃H] (4), whilst recrystallisation of (2) prior to addition of the acid (‘stepwise’ process) produced a green, needle-like Cu(II) complex, [Cu^(II)(dmp) · (H₂O)₂ · C₆H₅PO₂(OH)] [C₆H₅PO₂(OH)] (3). However, addition of excess dmp during the ‘stepwise’ process forced the equilibrium towards product (4) and resulted in an optimum yield (99%). The structure of (4) was similar to the phen analogue, [Cu^(II)Cl(phen)₂] · [C₆H₅PO₂(OH) · C₆H₅PO(OH)₂] (1) [R. Clarke, K. Latham, C. Rix, M. Hobday, J. White, CrystEngCommun. 7(3) (2005), 28-36], but the presence of dmp exerted some influence on global packing, whilst (3) exists as a polymeric layered material. In contrast, reaction of copper(I) with di-2-pyridyl ketone (dpk), followed by phenylphosphonic acid produced purple/blue Cu(II) species, [Cu^(II)(dpk · H₂O)₂] Cl₂ · 4H₂O (5), and [Cu^(II)(dpk · H₂O)₂] · [C₆H₅PO₂(OH)₂ · C₆H₅PO(OH)₂] (6), respectively, i.e., in both cases oxidation of copper occurred. Solid-state luminescence was observed in (2) and (4). The latter showing a 5-fold enhancement in intensity.     

Copper(I)-organophosphine complexes of bis(3,5-dimethylpyrazol-1-yl)dithioacetate ligand

Copper(I) complexes have been synthesized from the reaction of CuCl, monodentate tertiary phosphines PR₃ (PR₃ = P(C₆H₅)₃; P(C₆H₅)₂(4-C₆H₄COOH); P(C₆H₅)₂(2-C₆H₄COOH); PTA, 1,3,5-triaza-7-phosphaadamantane; P(CH₂OH)₃, tris(hydroxymethyl)phosphine) and lithium bis(3,5-dimethylpyrazolyl)dithioacetate, Li[LCS₂]. Mono-nuclear complexes of the type [LCS₂]Cu[PR₃] have been obtained and characterized by elemental analyses, FT-IR, ESI-MS and multinuclear (¹H, ¹³C and ³¹P) NMR spectral data; in these complexes the ligand behaves as a κ³-N,N,S scorpionate system. One exception to this stoichiometry was observed in the complex [LCS₂]Cu[P(CH₂OH)₃]₂, where two phosphine co-ligands are coordinated to the copper(I) centre. The solid-state X-ray crystal structure of [LCS₂]Cu[P(C₆H₅)₃] has been determined. The [LCS₂]Cu[P(C₆H₅)₃] complex has a pseudo tetrahedral copper site where the bis(3,5-dimethylpyrazolyl)dithioacetate ligand acts as a κ³-N,N,S donor.     

Mixed-solvothermal syntheses, structures and luminescence properties of two new Zn(II) phosphonates with layered and 3D framework structures

Two new zinc phosphonates with 2-hydroxyphosphonoacetic acid (HPAA) and 1-hydroxyethylidenediphosphonic acid (hedpH₄), [Zn₂{HO₃PCH(OH)CO₂}₃]·2NH₂(CH₃)₂·3H₂O (1) and [Zn₃{CH₃C(OH)(PO₃)₂}₂]·2NH₂(CH₃)₂·H₂O (2) have been synthesized under mixed-solvothermal conditions at 160 °C and structurally characterized by X-ray single-crystal diffraction, X-ray powder diffraction, infrared spectroscopy and elemental analysis. The structure of compound 1 comprises Zn1O₆ and Zn2O₆ octahedra connected by [HO₃PCH(OH)CO₂]²⁻ to form a 2D layered structure with one-dimensional channel system along c-axis direction, and the protonated dimethylamine cations are being located between two adjacent layers. Interestingly the layers of 1 arranged in an alternative sequence (ABAB). Compound 2 features a 3D framework structure with channels along the b- and c-axis, respectively. The charge-compensating protonated Hdma⁺ cations and solvate water molecules are located inside the channels along the c-axis. A notable feature for compound 2 is the presence of the alternate left- and right-handed helical chains in the structure. The luminescence properties of compounds 1 and 2 have also been studied.     

Dinitrosyl iron complexes [E5Fe(NO)2] (E = S, Se): A precursor of Roussin’s black salt [Fe4E3(NO)7]

[PPN][Se₅Fe(NO)₂] (1) and [K-18-crown-6-ether][S₅Fe(NO)₂] (2′) were synthesized and characterized by IR, UV-Vis, EPR spectroscopy, magnetic susceptibility, and X-ray structure. [PPN][Se₅Fe(NO)₂] easily undergoes ligand exchange with S₈ and (RS)₂ (R = C₇H₄SN (5), o-C₆H₄NHCOCH₃ (6), C₄H₃S (7)) to form [PPN][S₅Fe(NO)₂] and [PPN][(SR)₂Fe(NO)₂]. The reaction displays that [E₅Fe(NO)₂]⁻ (E = Se (3), S (4)) facilely converts to [Fe₄E₃(NO)₇]⁻ by adding acid HBF₄ or oxidant [Cp₂Fe][BF₄] in THF, respectively. Obviously, complexes 1 and 2′ serve as the precursors of the Roussin’s black salts 3 and 4. The electronic structure of {Fe(NO)₂}⁹ core of [Se₅Fe(NO)₂]⁻ is best described as a dynamic resonance hybrid of {Fe⁺¹(NO)₂}⁹ and {Fe⁻¹(NO⁺)₂}⁹ modulated by the coordinated ligands. The findings, EPR signal of g = 2.064 for 1 at 298 K, implicate that the low-molecular-weight DNICs and protein-bound DNICs may not exist with selenocysteine residues of proteins as ligands, since the existence of protein-bound DNICs and low-molecular-weight DNICs in vitro has been characterized with a characteristic EPR signal at g = 2.03. In addition, complex 2′ treated human erythroleukemia K562 cancer cells exposed to UV-A light greatly decreased the percentage survival of the cell cultures.     

Iron(III), chromium(III) and cobalt(II) complexes with squarate: Synthesis, crystal structure and magnetic properties

The preparation and variable temperature-magnetic investigation of three squarate-containing complexes of formula [Fe₂(OH)₂(C₄O₄)₂(H₂O)₄]·2H₂O (1) [Cr₂(OH)₂(C₄O₄)₂(H₂O)₄]·2H₂O (2) and [Co(C₄O₄)(H₂O)₄]_n (3) [H₂C₄O₄ = 3.4-dihydroxycyclobutene-1,2-dione (squaric acid)] together with the crystal structures of 1 and 3 are reported. Complex 1 contains discrete centrosymmetric [Fe₂(OH)₂(C₄O₄)₂(H₂O)₄] diiron(II) units where the iron pairs are joined by a di-μ-hydroxo bridge and two squarate ligands acting as bridging groups through adjacent oxygen atoms. Two coordinated water molecules in cis position complete the octahedral environment at each iron atom in 1. The iron-iron distance with the dinuclear unit is 3.0722(6) Å and the angle at the hydroxo bridge is 99.99(7)°, values which compare well with the corresponding ones in the isostructural compound 2 (2.998 Å and 99.47°) whose structure was reported previously. The crystal structure of 3 contains neutral chains of squarato-O¹,O³-bridged cobalt(II) ions where four coordinated water molecules complete the six-coordination at each cobalt atom. The cobalt-cobalt separation across the squarate bridge is 8.0595(4) Å. A relatively important intramolecular antiferromagnetic coupling occurs in 1 whereas it is very weak in 2, the exchange pathway being the same [J = −14.4 (1) and −0.07 cm⁻¹ (2), the spin Hamiltonian being defined as ]. A weak intrachain antiferromagnetic interaction between the high-spin cobalt(II) ions occurs in 3 (J = −0.30 cm⁻¹). The magnitude and nature of these magnetic interactions are discussed in the light of their respective structures and they are compared with those reported for related systems.     

Synthesis and characterization of 8-quinolinolato vanadium(IV) complexes

Reaction of vanadium(III) chloride with 8-quinolinol (Hqn) gave a mononuclear vanadium(IV) complex, [VOCl₂(H₂O)₂] 1) · 2H₂qn · 2Cl · CH₃CN, and three dinuclear vanadium(IV) complexes: [V₂O₂Cl₂(qn)₂(H₂O)₂] (2) · Hqn, [V₂O₂Cl₂(qn)₂(C₃H₇OH)₂] (3), and [V₂O₂Cl₂(qn)₂(C₄H₉OH)₂] (4). Reaction of vanadium(III) chloride with 5-chloro-8-quinolinol (HClqn) gave four dinuclear vanadium(IV) complexes: [V₂O₂Cl₂(Clqn)₂(H₂O)₂] (5) · 2HClqn, [V₂O₂Cl₂(Clqn)₂(C₃H₇OH)₂] (6), [V₂O₂Cl₂(Clqn)₂(C₆H₅CH₂OH)₂] (7), and [V₂O₂Cl₂(Clqn)₂(C₄H₉OH)₂] (8) · 2C₄H₉OH. Reaction of vanadium(III) chloride with 5-fluoro-8-quinolinol (HFqn) gave two dinuclear vanadium(IV) complexes: [V₂O₂Cl₂(Fqn)₂(H₂O)₂] (9) · HFqn · 2H₂O and V₂O₂Cl₂(Fqn)₂(C₃H₇OH)₂] (10). X-ray structures of 1 · 2H₂qn · 2Cl · CH₃CN, 3, 4, 6, 7, 8 · 2 t-BuOH, and 10 have been determined. As to the mononuclear species 1 · 2H₂qn · 2Cl · CH₃CN, coordination of Hqn to vanadium does not occur, but protonation to Hqn occurs to give H₂qn⁺, which links 1’s through hydrogen bonding, while each of the dinuclear species has a terminal and a bridging qn (or Clqn, Fqn) ligand, giving rise to a (V-O)₂ ring. Magnetic measurements of 3, 4, 6, 7, and 10 in solid form show very weak antiferromagnetic behavior, and the effective magnetic moments are close to spin only value (2.44) of d¹-d¹ system, while ESR of 3 in THF shows dissociation to monomeric species. Change from mononuclear, 1, to dinuclear, 2, species was followed by the change of electronic spectrum.     

Preparation, structures and properties of dinuclear and trinuclear copper(II) complexes bridged by one oximato and one hydroxo ligands

The dinuclear and trinuclear copper(II) complexes [Cu₂(L)(OH)(ClO₄)(phen)(H₂O)]ClO₄ · [Cu₂(L)(OH)(ClO₄)₂(phen)(CH₃OH)] (1) and [Cu₃(L)₂(OH)₂(H₂O)₂](NO₃)₂ (2) (HL=2-[2-(α-pyridyl)ethyl]imino-3-butanone oxime and phen=1,10-phenanthroline) were prepared and their crystal structures have been determined by X-ray crystallography. Complex 1 is composed of [Cu₂(L)(OH)(ClO₄)(phen)(H₂O)]ClO₄ (1a) and [Cu₂(L)(OH)(ClO₄)₂(phen)(CH₃OH)] (1b). In 1a and 1b, one oximato of L and one hydroxo group bridge two copper(II) ions. The linear trinuclear cation [Cu₃(L)₂(OH)₂(H₂O)₂]²⁺ in 2 is centrosymmetric, and one oximato and one hydroxo group bridge the central and terminal copper(II) ions. The strong antiferromagnetic interactions within the dinuclear and trinuclear complexes 1 and 2 have been observed (2J=∼−900 cm⁻¹ for 1 and 2, respectively, H=−2JS₁·S₂).     

Aryldiazenido derivatives: A new entry to the functionalization of Keggin polyoxometalates

A series of aryldiazenido polyoxomolybdates of the type (nBu₄N)₂[Mo₅O₁₃(OMe)₄(NNAr){Na(MeOH)}] (Ar = C₆F₅, 1; Ar = O₂N-o-C₆H₄, 2; Ar = O₂N-m-C₆H₄, 3; Ar = O₂N-p-C₆H₄, 4a; Ar = (O₂N)₂-o,p-C₆H₃, 5) have been obtained by controlled degradation of the parent compounds (nBu₄N)₃[Mo₆O₁₈(NNAr)] with NaOH in methanol. They have been characterized by elemental analysis and UV-Vis and IR spectroscopy. In addition, 4a has been characterized by ⁹⁵Mo NMR spectroscopy and the crystal structure of (nBu₄N)₂[Mo₅O₁₃(OMe)₄(NNC₆H₄-p-NO₂){Na(H₂O))]·H₂O (4b) has been determined by X-ray diffraction. The molecular structure of the anion of 4b features a lacunary Lindqvist-type anion [Mo₅O₁₃(OMe)₄(NNC₆H₄-p-NO₂)]³⁻ interacting with a sodium cation through the four terminal axial oxygen atoms. The 1:1 sodium complexes react with BaCl₂ and BiCl₃ to yield 2:1 complexes which have been isolated as (nBu₄N)₄[Ba{Mo₅O₁₃(OMe)₄(NNAr)}₂] (Ar = C₆F₅, 6; Ar = O₂N-p-C₆H₄, 7) and (nBu₄N)₃[Bi{Mo₅O₁₃(OMe)₄(NNAr)}₂] (Ar = C₆F₅, 8; Ar = O₂N-p-C₆H₄, 9). X-ray crystallography analysis of 9·Me₂CO has shown that the tetradentate [Mo₅O₁₃(OMe)₄(N₂C₆H₄-p-NO₂)]³⁻ anions provide a square-antiprismatic environment for Bi. In contrast, IR spectroscopy provides evidence for a square-prismatic environment of Ba in 6 and 7. In acetonitrile-methanol mixed solvent, [Mo₅O₁₃(OMe)₄(NNAr)]³⁻ and [PW₁₁O₃₉]⁷⁻, generated in situ by alkaline degradation of their respective parents, [Mo₆O₁₈(NNAr)]³⁻ and [PW₁₂O₄₀]³⁻, react together to give the Keggin-type diazenido compounds (nBu₄N)₄[PW₁₁O₃₉(MoNNAr)] (Ar = O₂N-o-C₆H₄, 10; Ar = O₂N-m-C₆H₄, 11; Ar = O₂N-p-C₆H₄, 12), which have been characterized by ³¹P and ¹⁸³W NMR spectroscopy.     

Synthesis and X-ray structures of rhenium(I) carbonyl aminoalkoxide and aminocarboxylate complexes

The complexes [Re{MeN(CH₂CH₂O)(CH₂CH₂OH)-κ³N,O,O}(CO)₃] (1), [Re{N(CH₂CH₂O)(CH₂CH₂OH)₂-κ³N,O,O}(CO)₃] (2), [Me₃NH]₂[(OC)₃Re{N(CH₂CO₂)₂-κ³N,O,O}CH₂CH₂{N(CH₂CO₂)₂-κ³N,O,O}Re(CO)₃] (3), [Me₃NH]₂[Re₂{μ₂-2,6-(O₂C)₂(C₅H₃N)-κ³N,O,O}₂(CO)₆] (4) and [Re₂{μ₂-2,6-(OCH₂)(C₅H₃N)(CH₂OH)-κ²N,O}₂(CO)₆] (5) were synthesized in high yields via the reactions of [Re₂(CO)₁₀] and Me₃NO with MeN(CH₂CH₂OH)₂, N(CH₂CH₂OH)₃, EDTA, pyridine-2,6-dicarboxylic acid and pyridine-2,6-dimethanol, respectively. Complexes 1-5 were characterized by IR and ¹H NMR spectroscopy, elemental analysis and X-ray crystallography.     

Cobalt(II) complexes of the antibiotic sulfadiazine, the X-ray single crystal structure of [Co(C10H9N4O2S)2(CH3OH)2]

Cobalt(II) complexes of sulfadiazine formulated as [Co(C₁₀H₉N₄O₂S)₂(CH₃OH)₂] and [Co(C₁₀H₉N₄S)₂(H₂O)₂] have been synthesized and characterized by elemental analysis, infrared and UV-Vis spectroscopy and magnetic susceptibility measurements. The crystal structures of the complex [Co(C₁₀H₉N₄O₂S)₂(CH₃OH)₂] and of free sulfadiazine are also reported. The cobalt complex and the sulfadiazine ligand both crystallize in the monoclinic space group, P21/c, with sulfadiazine acting as a bidentate ligand. Cobalt is coordinated to two-sulfonamide nitrogen and the pyrimidine nitrogen of the sulfadiazine. Two molecules of methanol complete the octahedral geometry around the cobalt, with interligand hydrogen bonding between methanol and sulfadiazine. Infrared spectroscopy confirmed the presence of water molecule in the coordination sphere of [Co(C₁₀H₉N₄S)₂(H₂O)₂]. The electronic spectra and magnetic moments of both complexes were similar, indicating that both complexes have similar structure.     

Monoorganotin-polyoxometal-compounds. Part IV: Na2[(PrSn3)(OV)4O10(OH)3]·5H2O·3DMSO, a novel branched tetravanadate(V) stabilized by a trimeric monoorganotin-oxo-hydroxo unit

Via self-assembly of the molecular precursors sodium orthovanadate and isopropyltin-dihydroxide-chloride the unprecedented organic-inorganic hybrid polyoxoanion [(ⁱPrSn)₃(OV)₄O₁₀(OH)₃]²⁻ was synthesized in dimethylsulfoxide (DMSO) and isolated as its sodium salt Na₂[(ⁱPrSn)₃(OV)₄O₁₀(OH)₃]·5H₂O·3DMSO. This spherical nanosized anion is composed of two different structural subunits, a well-known trinuclear monoorganotin-polyoxo-hydroxo unit with octahedrally coordinated tin atoms and a new open-chain, branched isopolyoxo tetravanadate(V) with tetrahedrally coordinated vanadium atoms.