Synthesis and structure of the monometallic cationic complex [Cp(CO)2Fe{η-(CH2CHCH2CH3)}]PF6 (Cp = η-C5H5)

The bimetallic carbocation complex [{Cp(CO)₂Fe}₂(μ-C₄H₇)]PF₆ reacted with trifluoroacetic acid to give the mononuclear cationic complex [Cp(CO)₂Fe{η²-(CH₂CHCH₂CH₃)}]PF₆, which formed yellow orthorhombic crystals in the space group P2₁2₁2₁ with a = 7.652(4), b = 13.422(7), c = 14.037(7); α = β = γ = 90.00 and Z = 4. The carbocation is coordinated to the metal in a η²-fashion forming a chiral metallacyclopropane type structure. The β-CH carbon (C9) is disordered over two positions (C9A and C9B), each having about 50% occupancy. This is attributed to there being both the R and S enantioface isomers in equal amounts in the crystal sample. NMR data indicate that the metallacyclopropane structure observed in the solid state is preserved in solution.     

Synthesis,structure and properties of eight novel molybdenum(VI) complexes of the types: [MoO2LD] and [{MoO2L}2D] (L = thiosemicarbazonato ligand,D = N-donor molecule)

Eight new molybdenum(VI) complexes with 4-(diethylamino)salicylaldehyde and 2-hydroxy-3-methoxybenzaldehyde thiosemicarbazones have been prepared. They were characterized as mononuclear [MoO₂LD] or dinuclear [{MoO₂L}₂D] complexes. In all the compounds the MoO₂²⁺ core is coordinated by a tridentate ONS thiosemicarbazonato ligand and by the N-donor molecule (imidazole, pyridine or γ-picoline). All the complexes were characterized by chemical analysis, IR spectroscopy and thermogravimetry. Three of the mononuclear complexes, dioxo[(2-hydroxy-3-methoxybenzaldehyde thiosemicarbazonato)(pyridine)]molybdenum(VI), dioxo[(2-hydroxy-3-methoxybenzaldehyde thiosemicarbazonato)(γ-picoline)]molybdenum(VI) and dioxo[(2-hydroxy-3-methoxybenzaldehyde thiosemicarbazonato)(imidazole)]molybdenum(VI) were also characterized by single-crystal X-ray structural analysis. A spectrophotometric method for the determination of molybdenum based on extraction of ion-pairs formed by the cationic surfactant and the [MoO(SCN)₄]⁻ anion is described.     

Metal derivatives of thiosemicarbazones: crystal structure of [chloro bis(triphenylphosphino) (thiophene-2-carbaldehyde thiosemicarbazone) copper(I)] complex

Reactions of copper(I) halides (X = Cl, Br, I) with thiophene-2-carbaldehyde thiosemicarbazone and triphenylphosphine in 1 : 1 : 2 molar ratio yield tetrahedral mononuclear complexes, [CuX(η¹-S-Httsc)(Ph₃P)₂] (X = Cl, 1; Br, 2; I, 3), characterized by elemental analysis, IR, NMR (¹H, ¹³C, ³¹P), and single crystal X-ray crystallography (1). The unit cell of 1 has two independent distorted tetrahedral molecules (1a and 1b) with different bond parameters. One acetonitrile is entrapped between them. Crystal data: C₈₆H₇₇Cl₂Cu₂N₇P₄S₄ 1: triclinic, P-1, a = 12.8810(9), b = 18.5049(13), c = 18.7430(13) Å, α = 63.7130(10), β = 89.0960(10), γ = 85.5010(10)°, V = 3992.4(5) ų, Z = 2, R _(int) = 0.0314. Bond parameters: 1a, Cu(1A)–Cl(1A), 2.3803(5); Cu(1A)–S(1A), 2.3822(5); Cu(1A)–P(1A), 2.2498(5) Å; P(1A)–Cu(1A)–P(2A), 124.294(19)°; 1b, Cu(1B)–Cl(1B), 2.3975(5); Cu(1B)–S(1B), 2.3756(5); Cu(1B)–P(1B), 2.2777(5) Å; P(1B)–Cu(1B)–P(2B), 127.156(19)°.     

Theoretical study of inner and outer mononuclear complexes of Co(II), Ni(II), and Cu(II) with a compartmental hexadentate Schiff base derived from 3-formylsalicylic acid

Density functional theory (B3LYP/6-31G(d)) has been applied for optimization and calculation of the vibrational spectra of the compartmental hexadentate Schiff base derived from 3-formylsalicylic acid and 4,5-dichloro-1,2-phenylenediamine and 12 of its mononuclear complexes with Co(II), Ni(II), and Cu(II). Six of these complexes have the metal ion occupying the inner, N₂O₂, or the outer, O₂O₂, coordination sites in square planar geometry. The other six complexes possess octahedral geometry, occupying the inner or the outer coordination sites coordinating, additionally, to two waters. Significant changes in the ligand geometry have been observed in all complexes to permit efficient complexation with the metal. Assignments of the infrared bands are proposed based on calculations. Vibrational frequencies that are important for assignment and confirmation of the coordination sites are reported. Comparison of the total energies of the complexes reveals that inner complexes are more stable than corresponding outer complexes. Selectivity of metal ions to the coordination sites is also discussed.     

Synthesis,characterization, and interaction with DNA of Cu(II) and Zn(II) complexes with 2,2′-bipyridyl-6,6′-dicarboxylic acid

Two transition metal complexes, [Cu₂(bpdc)₂H₂O]·2H₂O (1) and Zn(bpdc)(H₂O)₂ (2) (H₂bpdc?=?2,2′-bipyridine-6,6′-dicarboxylic acid), were synthesized and characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Complex 1 is dinuclear with two five-coordinate cupric ions and 2 is mononuclear with one six-coordinate zinc. Interactions of 1 and 2 with DNA have been investigated using UV–Vis absorption spectra. The cleavage reaction on DNA has been monitored by agarose gel electrophoresis.     

Supramolecular assembly of p-sulfonatecalix[4]arene through aquated neodymium (III) ions

A novel mononuclear complex of p-sulfonatecalix[4]arene and neodymium (III) ions in the presence of pyridine N-oxide has been investigated by X-ray diffraction study, which reveal that the bi-layer sheet structure is formed in the solid state. An aquated neodymium ion connects the adjacent calixarene-pyridine N-oxide complex units through multiple hydrogen bonds to stabilize the bi-layer structure.     

Formations and electrochemical behavior of mononuclear and binuclear molybdenum dithiolene complexes with nitrosyl ligands: Evidence for the formation of a coordinatively unsaturated species [CpMo(NO)(dithiolene)]

The one-pot reaction of [Cp^∗Mo(NO)(CO)₂] with elemental sulfur and dimethyl acetylenedicarboxylate (C₂Z₂ (Z = COOMe)) gave the [2+2] cycloadduct of the mononuclear molybdenum dithiolene complex [Cp^∗Mo(NO)(S₂C₂Z₂)(C₂Z₂)] (1), and some binuclear complexes:[Cp^∗Mo(NO)(S₂C₂Z₂)]₂ (2), [Cp^∗₂Mo₂(NO)₂S₂(S₂C₂Z₂)] (3) and [Cp^∗Mo(NO)S₂]₂ (4).The reaction of [Cp^∗Mo(NO)(Cl)(μ-Cl)]₂ with OC{S₂C₂(COOMe)₂} in the presence of sodium methoxide also produced complex 2 and the paramagnetic Cp^∗Mo bisdithiolene complex [Cp^∗Mo(S₂C₂Z₂)₂] (5, Z = COOMe).The structures of complexes 1-5 were determined by X-ray crystal structure analysis.The nitrosyl ligands of complexes 1-4 showed a linear coordination to the molybdenum center (the Mo-N-O bond angles = 169-174°), and their N-O bond lengths were 1.17-1.20 Å.In the binuclear complexes 2-4, two nitrosyl ligands were placed at cis-position.Complexes 1 and 2 were characterized by cyclic voltammetry and spectroelectrochemistry (visible and IR). The electrochemical reduction of the dimeric complex 2 formed the monomeric dithiolene complex[Cp^∗Mo(NO)(S₂C₂Z₂)]⁻ (X⁻) whose lifetime was several minutes. When the anion X⁻ was electrochemically oxidized, the coordinatively unsaturated species X was generated, but it was immediately dimerized to afford the original dimeric complex 2. The reduction of the complex 1 included the elimination of the bridged DMAD moiety (C₂Z₂) to give the anion X⁻.     

Hydrothermal synthesis and crystal structure of a novel luminescent europium complex of 2,5-pyridinedicarboxylic acid

A novel europium complex, Eu(Hdinic)(dinic)(H₂O)₅·4H₂O (dinic = 2,5-pyridinedicarboxylic acid), has been synthesized under hydrothermal conditions and characterized structurally by X-ray diffraction methods. The complex has a mononuclear molecular structure, is monoclinic, space group C2/c, with a?=?13.877(5), b?=?9.632(3), c?=?32.991(11)?Å, β?=?93.414(4)°, V?=?4402(2)?ų, D _c?=?1.948?Mg?m^?3, Z?=?8, F(000)?=?2576, R ₁?=?0.0320. Its photophysical properties are reported.     

Recombination of Coordination Bonds of a Mononuclear Precursor into a 3D d‐d′ Heterometallic Coordination Polymer with Double Helices

Abstract. Based on a mononuclear precursor [Mn(Hstp)₂(4,4′‐Hbpy)₂] ( 1 ), a hetero‐metallic complex, [Mn₂Ni(stp)₂(4,4′‐bpy)(H₂O)₄] ( 2 ) [stp = 2‐sulfoterephthalate, 4,4′‐bpy = 4,4′‐bpyridine] was synthesized by solvothermal reaction. Single‐crystal X‐ray diffraction analysis reveals that the Mn^II ion of the precursor 1 is hexacoordinate by four oxygen atoms from two Hstp^2– anions and two nitrogen atoms from two protonated 4, 4′‐Hbpy, and hydrogen bonding plays a significant role in constructing 3D supramolecular structure. While complex 2 features a self‐weaving framework from 1D straight chains and 2D wavy networks with double helical chains. Magnetic behavior of complex 2 was analyzed in connection with its crystal structure, which exhibits the weak antiferromagnetic interactions between the Mn^II and Ni^II ions.     

Ring-opening Copolymerization of Cyclohexene Oxide and Maleic Anhydride Catalyzed by Mononuclear [Zn（L）（H2O）] or Binuclear [Zn2（L）（OAc）2（H2O）] Complex Based on the Salen-type Schiff-base Ligand

From the self-assembly of the typical Salen-type Schiff-base ligand H2L and Zn(OAc)2·2H2O in the molar ratio of 1:1 or 1:2, the mononuclear [Zn(L)(H2O)](1) or binuclear [Zn2(L)(OAc)2(H2O)](2) are obtained, respectively. For both complexes 1 and 2, the unsaturated five-coordinate coordination environment to the catalytic active centers(Zn2+ ions) permits the monomer insertion for the effective solution copolymerization of cyclohexene oxide and maleic anhydride. All the solution copolymerizations afford poly(ester-co-ether)s, while lower catalyst and co-catalyst concentrations are helpful for the formation of alternating polyester. Of the three co-catalysts, 4-(dimethylamino)pyridine is found to be the most efficient, while an excess thereof is detrimental for chain growth of the copolymers.