Synthesis and laser application of the dithiolene nickel complex compounds

A series of dithiolene nickel complex compounds with a general formula (RCSCSR′)₂Ni that have an intense absorption band in near-IR region were successfully synthesized and the maximum IR absorption wavelengths of these dyes vary from 875 to 1495 nm in different solvents. Their characteristics of Q-switching and mode-locking for different lasers were investigated. Q-switched 1064 and 1079 nm laser with a polymer film or organic solution work satisfactorily and the pulse widths are 4–10 ns. The dyes in a variety of solutions show excellent properties in mode-locking the 1079 nm laser, particularly in mode-locking the 1340 nm laser. The pulse widths are 90–120 ps. The experimental results show that the choice of different ring substitutes and solvents will greatly influence the corresponding dye laser properties. It is also implied that BDN16 and BDN17 as the mode-locking dyes for the 1500 nm laser are satisfactory.     

Order-disorder transition coupled with magnetic bistability in the ferricinium salt of a radical nickel dithiolene complex

The ferricinium salt of the anionic, S = (1)/(2), dithiolene complex [Ni(tfadt)(2)](-) (where tfadt is the asymmetrically substituted 2-(trifluoromethyl)acrylonitrile-1,2-dithiolate) crystallizes at room temperature (rt) into uniform chains of dithiolene complexes, separated by ferricinium cations. Both ionic entities are characterized by disorder affecting one CF(3) and one Cp moiety. Above 250 K, this compound displays a Curie-type behavior. At lower temperatures, two first-order transitions around 249 and 137 K are revealed by susceptibility measurements and the observation of hysteresis effects. Crystal structure determinations performed at 230 and 120 K show that the high-temperature transition is associated with an ordering of the CF(3) and Cp groups together with a dimerization of the anionic stacks that thus induces a drop of the susceptibility. The second, low-temperature transition leads to a tetramerization of these nickel dithiolene stacks now in a complete diamagnetic state while the remaining susceptibility originates from the sole ferricinium contribution. The first order character of the 249 K transition with its associated bistable behavior is likely correlated with the structural order-disorder transition, an original behavior in this class of materials where bistability is most often associated with a strengthening of interstack intermolecular interactions (hydrogen bonding, pi-pi interactions ...).     

Dithiolene transfer from nickel to a dimolybdenum centre: the first dithiolene alkyne complex

Transfer of dithiolene ligands from [Ni(S₂C₂Ph₂)₂] to the dimolybdenum complex [Mo₂(μ-C₂R₂)(CO)₄Cp₂] (R=CO₂Me, Cp=η-C₅H₅) affords the first example of a dithiolene alkyne complex, [Mo₂(μ-C₂R₂)(μ-S₂C₂Ph₂)₂Cp₂], together with [Mo₂(μ-SCRCR)(μ-SCPhCPh)Cp₂] in which sulfur transfer from dithiolene to alkyne has occurred.     

Color tuning of a nickel complex with a novel N2S2 pyridine-containing macrocyclic ligand

The novel pyridine-containing 14-membered macrocycle 3,11-dithia-7,17-diazabicyclo[11.3.1]heptadeca-1(17),13,15-triene (L), which contains an N2S2 donor set, was synthesized, and its protonation behavior was studied by absorption titration with CH3SO3H. The reaction of L with Pd(II) was studied spectroscopically, and the square-planar complex [Pd(L)](BF4) was isolated and characterized. The reactions between L and NiX2 x 6 H2O (X = BF4, ClO4) in ethanol or acetonitrile afforded the octahedral complexes [Ni(CH3CN)(H2O)(L)](X)2 and [Ni(H2O)2(L)](X)2, respectively. The square-planar complexes [Ni(L)](X)2 were obtained by heating these octahedral complexes. Spectrophotometric titrations of [Ni(L)](BF4)2 were performed with neutral and negatively charged ligands. The color of nitromethane solutions of this square-planar complex turns from red to cyan, purple, blue, yellow-green, and pink following addition of halides, acetonitrile, water, pyridine, and 2,2'-bipyridine, respectively. X-ray structural analyses were carried out on the {[Ni(ClO4)(H2O)(L)][Ni(H2O)2(L)]}(ClO4)3, [Ni(CH3CN)(H2O)(L)](ClO4)2, [{Ni(L)}2(mu-Cl)2](ClO4)2, and [{Ni(L)}2(mu-Br)2]Br2 x 2 CH3NO2 complexes.     

Soliton model of electron transfer in mixed-valence dimers and trimers

The soliton approximation is examined for mixed-valence dimers and trimers with one migrating electron. The calculations use Hamilton's canonical equations and a time-dependent wave function of the soliton type. In the two limiting cases (strong and weak vibronic coupling), the soliton approximation correlates well with the exact analytical solution. As in the adiabatic approximation at g²/v=1, the delocalized limit (quasifree electron) is transformed to the localized one (electron locked on the center). For molecular trimers, the soliton approximation allows us to reveal the cases where the transfer of an electron from the first to the third center is accompanied by electron density concentration on the intermediate center. Institute of Chemistry, Academy of Sciences, Moldova Republic. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 6, pp. 46–53, November–December, 1994. Translated by L. Smolina     

A new dithiolene complex magnet: [Ni(Cp*Rubdt)2][CF3SO3]

The unique salt [Ni(Cp*Rubdt)₂][CF₃SO₃], containing the features of both a metal dithiolene complex and a metallocene, has been studied by d.c. and a.c. magnetic susceptibility measurements. This indicated ferromagnetism with T_c=3.5 K as evidenced by splitting of the field-cooled and zero-field-cooled d.c. susceptibility, remnant magnetisation, a non-zero imaginary component and a peak in the real component of the a.c. susceptibility and magnetic hysteresis. Studies of magnetisation against field indicated superparamagnetic behaviour above the ordering temperature up to around 10–20 K, suggesting correlated behaviour of the spins in one or two dimensions before the onset of 3D order. In contrast to many mixed dithiolene complex—metallocene salts, the structure of the title compound ensures that no segregation of the dithiolene and metallocene components into separate stacks can occur, a structural feature that has previously led to interesting magnetic materials.     

The mechanism of alkene addition to a nickel bis(dithiolene) complex: the role of the reduced metal complex

The binding of an alkene by Ni(tfd)(2) [tfd = S(2)C(2)(CF(3))(2)] is one of the most intriguing ligand-based reactions. In the presence of the anionic, reduced metal complex, the primary product is an interligand adduct, while in the absence of the anion, dihydrodithiins and metal complex decomposition products are preferred. New kinetic (global analysis) and computational (DFT) data explain the crucial role of the anion in suppressing decomposition and catalyzing the formation of the interligand product through a dimetallic complex that appears to catalyze alkene addition across the Ni-S bond, leading to a lower barrier for the interligand adduct.     

Design and synthesis of the novel branched fluorinated surfactant intermediates with CF3CF2CF2C(CF3)2 group

Here we reported a novel and efficient method for the synthesis of the critical intermediates of branched fluorinated surfactants with CF₃CF₂CF₂C (CF₃)₂- group using HFPD as starting material. The reaction conditions were mild and easy to handle, which was promisingly applied to the industrial production.     

Synthesis and aggregation behavior of perylenetetracarboxylic diimide trimers with different substituents at bay positions

Three perylene tetracarboxylic diimide (PDI) trimers substituted with different side groups at the bay positions were prepared with the triazine ring as a linkage. The free rotation of C-N-C bonds between the triazine ring and the PDI unit provide these molecules with some flexibility. The UV-vis absorption and fluorescence spectra of these three compounds show different concentration-dependent behaviors, which depend on the side groups at the bay positions. Significant aggregation in organic solvents was revealed by the electronic absorption and emission spectra as well as the fluorescence quantum yield calculation. The aggregation behavior of these compounds in the solid state were investigated by X-ray diffraction (XRD), and the morphology of the aggregates was examined by atomic force microscopy (AFM). The aggregation of trimer 1 with two phenoxy groups at the 1 and 7 positions results in long nanofibers whereas trimers 2 and 3 with dipiperidinyl groups or tetraphenoxyl groups at the bay positions form only particles. The results of this research revealed that PDI trimers with flexible structures can also self-assemble into large ordered aggregates such as those with rigid structure. This information is believed to be useful in the design of novel nanoorganic materials.     

Kinetics of the reaction of NO2 with a macrocyclic nickel complex

The kinetics of the reaction between NO₂ and ([14]aneN₄)Ni²⁺ were determined by laser flash photolysis. The NO₂ was generated in two independent reactions, one of which is based on the photochemistry of (NH₃)₅CoNO₂²⁺, and the other on the photochemistry of HNO₂/NO₂^?. The results from both sets of experiments yielded a consistent value for the rate constant, k₁ = 1.2 × 10⁸ M^?1 s^?1 in aqueous solutions at pH 1–4. There was no evidence for the reverse reaction. NO₂ reacts with Fe_aq²⁺ more slowly, k_Fe ～ 2 × 10⁵ M^?1 s^?1. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 278–281, 2002     

Synthesis and characterisation of a mixed-valence Mn13 complex with S6 symmetry by using 2-phenoxybenzoate

The synthesis, structure and magnetic properties of [Mn(13)O(8)(OEt)6(O(2)CC(6)H(4)OPh)12] are reported as the first example of a high nuclearity manganese complex with 2-phenoxybenzoate: the complex possesses S6 symmetry and an S = 11/2 ground state.     

A donor--acceptor--donor bridging ligand in a class III mixed-valence complex

The novel mononuclear and dinuclear complexes [Ru(trpy)(bpy)(apc)][PF(6)] and [(Ru(trpy)(bpy))(2)(mu-adpc)][PF(6)](2) (bpy = 2,2'-bipyridine, trpy = 2,2':6',2' '-terpyridine, apc(-) = 4-azo(phenylcyanamido)benzene, and adpc(2)(-) = 4,4'-azodi(phenylcyanamido)) were synthesized and characterized by (1)H NMR, UV-vis, and cyclic voltammetry. Crystallography showed that the dinuclear Ru(II) complex crystallizes from diethyl ether/acetonitrile solution as [(Ru(trpy)(bpy))(2)(mu-adpc)][PF(6)](2).2(acetonitrile).2(diethyl ether). Crystal structure data are as follows: crystal system triclinic, space group P1, with a, b, and c = 12.480(2), 13.090(3) and 14.147(3) A, respectively, alpha, beta, and gamma = 79.792(3), 68.027(3), and 64.447(3) degrees, respectively, V = 1933.3(6) A(3), and Z = 1. The structure was refined to a final R factor of 0.0421. The mixed-valence complex with metal ions, separated by a through-space distance of 19.5 A, is a class III system, having the comproportionation constant K(c) = 1.3 x 10(13) and an intervalence band at 1920 nm (epsilon(max) = 10 000 M(-1) cm(-1)), in dimethylformamide solution. The results of this study strongly suggest that the bridging ligand adpc(2-) can mediate metal-metal coupling through both hole-transfer and electron-transfer superexchange mechanisms.     

A novel mixed-valence complex containing Co(II)(2)Co(III)(2) molecular squares with 4,5-imidazoledicarboxylate bridges

A heterometallic complex, Na(2)[Co(II)(2)Co(III)(2)(IDC(3-))(4)(bipy)(4)].12H(2)O (bipy = 2,2'-bipyridine), in which mixed-valence tetranuclear squares with imidazoledicarboxylate (IDC(3-)) linkers are tethered into a unique chain through disodium units, is hydrothermally synthesized and structurally and magnetically characterized.     

Electrical conductivity and spin crossover: a new achievement with a metal bis dithiolene complex

Three new compounds based on the cationic complex [Fe(III)(3-R-salEen)(2)]+ (salEen stands for N-(2-ethylamino)ethyl)-salicylaldimine, R = H, CH(3)O) with the electroactive Ni(dmit)(2) species as a counterion (dmit stands for 1,3-dithia-2-thione-4,5-dithiolato) have been synthesized and structurally and magnetically characterized. Compound 1 ([Ni(dmit)(2)][Fe(3-OMe-salEen)(2)]. CH(3)OH) shows an apparent hysteresis loop, due to an irreversible desolvatation process. Compound 2 ([Ni(dmit)(2)](NO(3))[Fe(salEen)(2)](2)) exhibits a gradual and incomplete spin transition. Compound 3 ([Ni(dmit)(2)](5)[Fe(salEen)(2)](2), 6CH(3)CN) is a fractional oxidation state complex, which behaves like a semiconductor and exhibits a gradual but complete spin transition between 300 and 4 K.     

One-pot synthesis of nickel porphyrins with 2-pyridine-acetyl substituents: the unexpected Sonogashira cross-coupling products

Nickel porphyrins with 2-pyridine-acetyl substituents were synthesized in one step by the Sonogashira cross-coupling method. The structures of the products were determined by elemental analysis, ¹H NMR, UV-Vis, and X-ray spectroscopic techniques. It is suggested that cross-coupling bromonated nickel porphyrins with 2-pyridine-ethyne first yielded nickel porphyrins with 2-pyridine-ethynyl substituents, followed by in situ hydrolysis to the final products, nickel porphyrins with 2-pyridine-acetyl substituents.     

Heterometallic mixed-valence complex with a {CoIICoIIICu2O4} core as a new type of cobalt-based oxide cubane

A tetranuclear heterometallic complex formulated as [Co₂Cu₂(L)₃(ea)(H₂O)(NCS)₂], where H₂L = 2-((2-hydroxyethyl)iminomethyl)-phenol and Hea = 2-aminoethanol, has been obtained by self-assembly and characterized by single crystal X-ray diffraction. The crystal structure of the complex represents a new {Co^IICo^IIIM₂} type of cobalt-based oxide cubane complex according to the classification which has been made via CSD structural analysis.     

A straightforward synthesis of diverse nickel dithiolene complexes appended with hydrogen-bond donor/acceptor groups

Nickel dithiolene complexes symmetrically appended with hydrogen-bond donor/acceptor functionalities such as imide, amide, or cyano/amide groups have been synthesized by a straightforward method of wide applicability starting from one single precursor. Single-crystal X-ray structures reveal the occurrence of one type of ribbon common to all compounds that is based on a recurrent self-complementary intermolecular hydrogen-bonded ring motif linking the symmetrically substituted complexes.     

Unexpected conversion of a hexacyanometallate to a homoleptic nitrile complex with triphenylborane substituents

The homoleptic, triphenylborane adduct of the hexacyanochromate anion was structurally characterized and found to be a product in which all six cyanide ligands have undergone isomerization to nitrile groups.