Sulfur-rich CpCo(dithiolene) complexes: Isostructural or non-isostructural couples of CpCo(III) with CpNi(III) dithiolene complexes

Eight new sulfur-rich [CpCo(dithiolene)] complexes were synthesized from [Zn(dmit)₂]²⁻ as a starting material. The structures, electrochemical behavior and electronic absorption spectra of the sulfur-rich [CpCo(S₂C₂S₂Y)] complexes could be compared with the early data of analogous Ni complexes. [CpCo(pddt)] (Y = -(CH₂)₃-), [CpCo(dpdt)] (Y = -CH₂C(CH₂)CH₂-), [CpCo(bddt)] (Y = -(CH₂)₄-), [CpCo(dtdt)] (Y = -CH₂SCH₂-) and [CpCo(poddt)] (Y = -CH₂C(O)CH₂-) crystallized in all isostructural with the corresponding paramagnetic [CpNi(dithiolene)] complexes, but [CpCo(dmid)] (Y = CO), [CpCo(dddt)] (Y = -(CH₂)₂-) and [CpCo(F₂pddt)] (Y = -CH₂CF₂CH₂-) crystallized in non-isostructural with them. These molecules are associated with intermolecular short S?S contacts in the crystals. [CpCo(F₂pddt)] did not show any remarkable S?S contacts but indicated interesting fluorine segregation and Cp?Cp face-to-face interactions. Redox potentials of [CpCo(dithiolene)] complexes were obtained with the cyclic voltammetry measurements and dimerized by electrochemical oxidations. Electronic absorption spectra of [CpCo(dithiolene)] complexes showed visible absorption in the range of 585-701 nm as lowest energy wavelengths (? = 9800-11,800 M⁻¹ cm⁻¹) in solutions, and they were higher energy than those of [CpNi(dithiolene)] complexes (near-IR).     

Two near-UV and visible chromophores of CpCo(Dithiolene) complexes with pyridinium-dicyanomethylide group

Tetracyanoethylene oxide (TCNEO) reacted with [CpCo(dithiolene)] (Cp = η⁵-cyclopentadienyl) complexes having 4-pyridyl or 3-pyridyl group to undergo a dicyanomethylation to the nitrogen atom on the pyridyl group. The reaction of [CpCo(S₂C₂(⁴Py)₂)] (1) with TCNEO formed both the monodicyanomethylated [CpCo(S₂C₂(⁴Py)(⁴Py-C(CN)₂))] (1a) and bisdicyanomethylated [CpCo(S₂C₂(⁴Py-C(CN)₂)₂)] (1b). [CpCo(S₂C₂(²Py)(⁴Py))] (2) reacted with TCNEO to give [CpCo(S₂C₂(²Py)(⁴Py-C(CN)₂))] (2a) but no dicyanomethylation occurred on the 2-pyridyl group. 2 reacted with excess TCNEO to form the only dicyanomethylated acetylene derivative ²Py-CC-(⁴Py-C(CN)₂) (2c), followed by a dissociation of the CpCoS₂ fragment. The monodicyanomethylated [CpCo(S₂C₂(ⁿPy-C(CN)₂)(2-thienyl))] (n = 4 (4a) or 3 (5a)) complexes were also prepared from [CpCo(S₂C₂(ⁿPy)(2-thienyl))] (n = 4 (4) or 3 (5)) and TCNEO. 1b was structurally characterized by X-ray diffraction study. The all dicyanomethylated [CpCo(dithiolene)] complexes showed the dithiolene LMCT absorption in the range of 605-644 nm (ε = 7000-9200 M⁻¹ cm⁻¹) and very strong absorption due to their pyridinium-dicyanomethylide moieties in near-UV region (e.g. 1b: λ_max = 470 nm, ε = 43,400 M⁻¹ cm⁻¹). The CV of the all dicyanomethylated complexes exhibited two reduction waves. The first reduction is due to Co^III/Co^II and the second one is due to the reduction of the pyridinium-dicyanomethylide moiety. The reduced 1b⁻ is stable enough for several minutes according to the visible spectroelectrochemical measurement. The ESR spectrum of 1b⁻ indicated eight hyperfine splittings due only to the interaction with the nuclear spin of cobalt (I = 7/2).     

CpCo(dithiolene) complexes of highly flexible oxddt ligand with two different Z-shaped and U-shaped structures

[CpCo(oxddt)] complex (2, oxddt = o-xylenediyldithioethylene-1,2-dithiolate, Cp = η⁵-cyclopentadienyl) was obtained from o-xylenediyldithioethylene-1,3-dithiol-2-one (OC(oxddt)) (1). 2 further reacted with diazoalkanes (N₂CHR) to form some alkylidene-bridged adducts [CpCo(CHR)(oxddt)] (R = H (3a), SiMe₃ (3b)). Adduct 3a further reacted with protic acids (HX) to give some S-methylated adducts [CpCo(X)(oxddt)(S-Me)] (X = Cl (4a), OCOCF₃ (4c)), followed by the Co-C bond cleavage in the three-membered cobaltathiirane ring. Two different Z-shaped and U-shaped molecular structures were observed by X-ray diffraction studies. In the former structure (Z), the dithiolene and o-xylylene planes are located at almost parallel position each other, and in the latter structure (U), both planes are not parallel but the o-xylylene moiety is located closer to the dithiolene plane than the Z-shaped one. The Z-shaped structure involves 1 and 2. The U-shaped structure involves 3a, 3b, 4a and 4c. Complex 1 showed a one-dimensional chain through intermolecular π-π interaction in the crystal. Complex 2 had a dimeric interaction between dithioethylenedithiolate moieties (S₂C₂S₂) in the oxddt. The SiMe₃ group in 3b was placed at an exo-position with respect to the cobaltadithiolene ring due to a steric hindrance from the U-shaped oxddt ligand. In 4a, the X and Me groups are located at the opposite side of the dithiolene plane (anti-form) but in 4c, both groups are presented at the same side of the dithiolene plane (syn-form). The NMR analysis of 4a in solution indicated existence of both anti- and syn-isomers (7:1).     

Reactivity and electrochemical behavior of ruthenium dithiolene complexes with coordinatively unsaturated metal centers: cycloaddition and dimerization reactions

The novel ruthenium dithiolene complexes [(arene)Ru{S₂C₂(COOMe)₂}] (arene = C₆H₆ (1a), C₆H₄(Me)(iPr) (1b), C₆Me₆ (1c)) were synthesized. The equilibrium between complex 1a and the corresponding dimer [(C₆H₆)Ru{S₂C₂(COOMe)₂}]₂ (1a′) was confirmed in solution. The reaction of complex 1a with dimethyl- or diethylacetylene dicaboxylate gave the alkene-bridged adducts [(C₆H₆)Ru{S₂C₂(COOMe)₂}{C₂(COOR)₂}] (R = Me (2a), Et (3a)) as [2 + 2] cycloaddition products formally. The reactions of complex 1a with diazo compounds also gave the alkylidene-bridged adducts [(C₆H₆)Ru{S₂C₂(COOMe)₂}(CHR)] (R = H (4a), SiMe₃ (5a), COOEt (6a)) as [2 + 1] cycloaddition products. The electrochemical behavior of complex 1a was investigated. The reductant of complex 1a was a stable species for several minutes. The oxidant of complex 1a was very unstable; the cation 1a⁺ formed was immediately converted to the corresponding cationic dimer 1a′⁺. The cationic dimer 1a′⁺ was stable for several minutes, and it was rapidly and quantitatively converted to the neutral complex 1a when it was reduced.     

Synthesis,structure and physical properties of nickel bis(dithiolene) complexes with different cations

A series of new complexes of multi-sulfur 1,2-dithiolene ligands, [Ru(bipy)₃][Ni(L)₂]₂ (bipy?=?2,2′-bipyridine; L?=?pddt (6,7-dihydro-5H-1,4-dithiepin-2,3-dithiolate), dddt (5,6-dihydro-1,4-dithiin-2,3-dithiolate)), have been synthesized and characterized. One typical complex, [Ru(bipy)₃][Ni(pddt)₂]₂·2H₂O (1), crystallized in an acentric space group of P2₁2₁2₁, with the cell dimensions of a?=?8.634(1), b?=?14.560(1), c?=?49.889(5)?Å, α?=?β?=?γ?=?90°, and Z?=?4. It consists of alternating columns of cations and anions along the a direction. The structure was refined by full matrix least squares methods to R ₁?=?0.0340, wR ₂?=?0.0670. Magnetic studies on [Ph₂Cr][Ni(dddt)₂] are also reported.     

Isostructural diamagnetic cobalt(III) and paramagnetic nickel(III) dithiolene complexes with an extended benzenedithiolate core [CpM(bdtodt)] (M = Co and Ni)

The isostructural diamagnetic [CpCo(bdtodt)] and paramagnetic [CpNi(bdtodt)] (Cp = η⁵-cyclopentadienyl, bdtodt:benzo[1,3]dithiol-2-one-5,6-dithiolato) complexes were prepared by starting from the corresponding bis(dithiocarbonate): benzo[1,2-d;4,5-d′]bis[1,3]dithiole-2,6-dione. Both Co and Ni complexes are isostructural and crystallize in the orthorhombic system, space group Pbca. The formally M^III (16-electron for Co^III and 17-electron Ni^III) complexes were investigated by X-ray structure analyses and exhibit the same two-legged piano-stool geometry. The CV of the radical [CpNi(bdtodt)] resulted in well-defined reversible reduction and oxidation waves. On the other hand, oxidation of [CpCo(bdtodt)] leads to dimerization in CH₂Cl₂ or reaction in the more coordinating CH₃CN solvent. The absorption maximum (λ_max) of [CpNi(bdtodt)] (741 nm) showed a more red shift compared with [CpCo(bdtodt)] (595 nm) in dichloromethane solution. The structural similarities, and electrochemical, spectroscopic and magnetic differences between various [CpCo(dithiolene)] and [CpNi(dithiolene)] complexes are further analyzed.     

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⁻.     

Diverse reactivities of aromaticity-unsaturation coexisted metalladithiolene rings

This review paper summarizes the reactivities of metal dithiolene complexes based on the ‘coexistence of aromaticity and unsaturation’ in the five-membered metallacycle, the so-called metalladithiolene ring (MS₂C₂). The 16-electron [LM(dithiolene)] (LM = CpM^III, Cp*M^III, (C₆R₆)M^II) complexes are coordinatively unsaturated and usually show M-S centered cycloaddition reactions with nucleophiles (e.g. diazoalkanes, organic azides, quadricyclane) and electrophiles (e.g. tetracyanoethylene oxide, activated acetylene). The resulting metalladithiolene cycloadducts, which have three-membered M-S-C or M-S-N rings, further react with protic acids or PR₃ to undergo the ring-opening reactions involving the M-C bond, M-S bond or M-N bond cleavages. Furthermore, diverse adduct dissociations are observed by thermal, photochemical or electrochemical redox reactions. Such reactions normally produce the original [LM(dithiolene)] complexes (non-adduct) and the eliminated fragments. Among them, the Co-S centered imido adduct [CpCo(dithiolene)(NR)] (R = Ts, Ms) reacted under thermal conditions in the presence of PR₃ to undergo the intramolecular imido migration reaction to the Cp ligand, giving [(C₅H₄-NHR)Co(dithiolene)] complexes. The M-S centered multinuclear cluster complexes are obtained by the reaction of [LM(dithiolene)] with low valent M(CO)_n complexes. The square-planar bis(dithiolene) complexes [M(dithiolene)₂]⁰ (M = Ni, Pd, Pt) or tris(dithiolene) complexes [M(dithiolene)₃]⁰ yield cycloaddition products with olefins. These reactions are due to ligand centered reactions made possible by a molecular orbital overlap between dithiolene LUMO and olefin HOMO. Similar ligand centered adducts are obtained by the reaction of dianionic [M(dithiolene)₂]²⁻ with haloalkanes or dihaloalkanes. Also these adducts of bis(dithiolene) complex are dissociated photochemically and electrochemically. This paper also describes the reactivities of organometallic o-carborane dithiolate complexes, which are generally formulated as [LM(S₂C₂B₁₀H₁₀)] (LM = CpCo, Cp*Rh, Cp*Ir, (p-cymene)Ru and (p-cymene)Os). Diverse addition reactions are reported; in particular, the reaction with acetylene involves B-H bond activation in the carborane moiety.     

Rare direct imidation of aromatic metallacycle by reaction of CpCo(dithiolene) complex with N-halosuccinimide

The aromatic [CpCo(S₂C₂(R)(H))] (R = Ph, Me, 9-phenanthryl, H) complexes reacted with N-halosuccinimides (NXS; X = Cl, Br, I) in carbon tetrachloride at room temperature to undergo the N-succinimide substitution reaction on the dithiolene ring, but no halogenated dithiolene complex was obtained. The imidation products [CpCo(S₂C₂(R)(N-sccinimide))] were yielded up to 64% where X = I and R = 9-phenanthryl. The reaction of [CpCo(S₂C₂(Ph)(H))] with N-bromophthalimide (NBP) also gave the imidation product [CpCo(S₂C₂(Ph)(N-phthalimide))]. This is the rare direct imidation reaction to an aromatic metallacycle by NXS. The reaction of [CpCo(S₂C₂H₂)] (R = H) with NIS afforded the double imidation product. One by-product in this reaction was the dithiolene-dithiolene homo-coupling product [CpCo(S₂C₂(R))]₂ (R = Ph, Me, 9-phenanthryl). The microwave-enhanced (MW) reactions were attempted in the carbon tetrachloride solution. Although the solution temperature increased up to only 43 °C by MW irradiation, the imidation reaction worked with short reaction time.     

Synthesis,crystal structures,antimicrobial activities,and DFT calculations of two new azido nickel(II) complexes

Two new complexes, [Ni(HL¹)(N₃)(μ_1,1N₃)]₂ (1) [HL¹: NC₅H₄CH₃C=NNH (C=O) NH₂] and [Ni(L²)N₃] (2) [HL²: NC₅H₄HC=N NH(C=S)NH₂], have been synthesized by reaction of Ni(OAC)₂·4H₂O and sodium azide with HL¹ and HL² and characterized by elemental analysis, FT-IR, and UV–vis spectral studies. Single-crystal X-ray diffraction reveals that 1 is dinuclear with nickel(II) in an octahedral environment of NNO donors of HL¹, two nitrogens of azide bridges and one nitrogen of terminal azide; 2 is mononuclear containing nickel(II) in a distorted square-planar environment of NNS donors of HL² and one terminal azide. The structures of 1 and 2 have been optimized by density functional theory. The results of antimicrobial activities of ligands, 1 and 2 demonstrated that HL² and 2 have good antimicrobial activity in contrast with HL¹ and 1, related to the presence of sulfur donor in HL².     

Syntheses, properties and structures of copper and nickel complexes of 6,7-dihydro-5H-1,4-dithiepin-2,3-dithiolate

The reaction of CuCl2-2H2O or NiCl2.6H2O with K2(C5H6S4) [potassium salt of 6,7-dihydro-5H-1,4-dithiepin-2,3-dithiolate] under nitrogen atmosphere resulted in the isolation of [Cu(C5H6S4)2]- or [Ni(C5H6S4)2]- as the tetrabutylammonium salt. Both complexes show characteristic IR and UV-Vis absorptions of transition metal dithiolenes. Cyclic voltammograms contain two waves indicating a two step electrochemical procedure [M(C5H6S4)2]0 = [M(C5H6S4)2]1-= [M(C5H6S4)2]2-. Single crystal structure study has been carried out on the nickel complex. Crystal of [Bu4N][Ni(C5H6S4)2] belongs to monoclinic space group P21/c with a=17.576(5), 6=10.883(2), c=17.773(4) A,B=91.07(2)0, Z=4, and o(calcd.)=1.348 g/cm3. Final result is R=0.059 for 2959 reflections. The NiS4 core exhibits square planar coordination with average Ni-S bond length of 2.134(5) A. There are not anion pairs in crystal. The anions stack along a and c axes while the cations intercalate in them. The nearest S-S contact is 4.429 A. The solid powder ESR s     

Syntheses,crystal structures,electrochemical studies,and antioxidant activities of zinc(II) and copper(II) complexes with bis(2-benzimidazolyl) aniline derivatives

Two ligands, bis(benzimidazol-2-ylmethyl) aniline (bba) and bis(N-methyl-benzimidazol-2-ylmethyl) aniline (Mebba), and their transition metal complexes [Zn(bba)(Br)₂]·2DMF (1) and [Cu(Mebba)(Br)₂]·2DMF (2) have been synthesized and characterized by elemental analyses, molar conductivities, UV–vis spectra, IR spectra, NMR spectroscopy, and X-ray crystallography. The structure around Zn(II) can be described as distorted tetrahedral. Complex 2 can be described as distorted trigonal bipyramidal. Cyclic voltammograms of 2 indicate a quasireversible Cu²⁺/Cu⁺ couple. Additionally, the antioxidant activities of the free ligands and their complexes were determined by the superoxide and hydroxyl radical scavenging methods in vitro. Complexes 1 and 2 possess potent hydroxyl radical scavenging activity and better than standard antioxidants such as vitamin C and mannitol. Complex 2 possesses excellent superoxide radical activity.     

Formations and structures of cobalt dithiolene complexes with nitrogen group-substituted cyclopentadienyl ligands

The cobalt dithiolene complex with the sulfonylamide-substituted Cp ligand [(C₅H₄-NHTs)Co{S₂C₂(COOMe)₂}] (1, Ts = p-SO₂C₆H₄Me) reacted with TsOH · H₂O to give [(C₅H₄-NH₂)Co{S₂C₂(COOMe)(H)}] (2), [(C₅H₄-NHTs)Co(S₂C₂H₂)] (3) and [(C₅H₄-NHTs)Co{S₂C₂(COOMe)(H)}] (4). Complex 1 was dissolved in a basic aqueous solution, and the anion reacted with Me₂SO₄ to form the N-methylated product [{C₅H₄-N(Me)Ts}Co{S₂C₂(COOMe)₂}] (5); the carboxylic acid complex [{C₅H₄-N(Me)Ts}Co{S₂C₂(COOMe)(COOH)}] (6) formed by a base hydrolysis. The X-ray crystal structures of complexes 4-6 and the methylsulfonylamide-substituted Cp complex [(C₅H₄-NHMs)Co{S₂C₂(COOMe)₂}] (7, Ms = SO₂Me) were determined. In the crystal structures of complexes 4 and 7, intermolecular hydrogen bondings of NH?O (ca. 2.1 Å) and NH?S (ca. 3.1 Å) were observed. Complex 6 showed the OH?O intermolecular hydrogen bonding (ca. 1.6 Å) of COOH moiety between two molecules, and these two molecules were assembling each other. Complexes 5 and 6 showed an intramolecular π-π interaction between the aromatic cobaltadithiolene and benzene rings, and complex 5 also has intermolecular π-π interactions between two benzene rings, and between two cobaltadithiolene rings.     

Homoleptic tris(dithiolene) and tetrakis(dithiolene) complexes of uranium(IV)

Reaction of UCl4 with 3 or 4 mol equiv of Na2dddt (dddt = 5,6-dihydro-1,4-dithiine-2,3-dithiolate) in THF afforded the first example of a tetrakis(dithiolene) metal compound, [Na4(THF)8U(dddt)4](infinity) (1). The red crystals of 1 are composed of infinite zigzag chains in which Na2(micro-THF)3 fragments ensure the linking of Na2(THF)5U(dddt)4 moieties; the uranium atom is in a dodecahedral environment of eight sulfur atoms. Treatment of UCl4 with 3 mol equiv of Na2dddt in pyridine gave a mixture of tris- and tetrakis(dithiolene) compounds. After addition of 18c6 (18-crown-6), only the tris(dithiolene) complex was obtained and crystallized as orange crystals of [Na(18c6)(py)2]2[U(dddt)3].2py (2.2py) in which the isolated [U(dddt)3]2- anion adopts a slightly distorted trigonal prismatic configuration. A few red crystals of the unsolvated complex 2 and the trinuclear anionic compound [Na(18c6)(py)2]3[Na{U(dddt)3}2] (3) were also obtained along with orange crystals of 2.2py. All the tris(dithiolene) compounds exhibit large folding of the dddt ligand and significant interaction between the C=C double bond and the metal center.     

Hydrogen bonding interaction of CpCo(Dithiolene) complex with monocyclic 2-pyridonyl substituent and unexpected formation of dithiolene-fused tricyclic pyridone derivative

One-pot reaction of [CpCo(CO)₂], elemental sulfur with some heterocycle-substituted alkynes (R-CC-HET) produced [CpCo(dithiolene)] complexes with ²PyOBn (2), with both ²PyOBn and 2-hydroxy-2-propyl groups (C(OH)Me₂) (5), both ²Py and C(OH)Me₂ (8), both ⁴Py and C(OH)Me₂ (11), and with ⁴Py substituent (13). A deprotection of benzyl group (Bn) from 2 with trimethylsilyl iodide formed [CpCo(dithiolene)] with 2-pyridonyl substituent (3). Heating reaction of 8 without any base resulted in the C(OH)Me₂ group elimination to form the 2-pyridylethylenedithiolate complex (9), but 11 underwent only dehydration at the C(OH)Me₂ under heating. While the preparation of 5, the benzyl free complex (6) was obtained as a main product. 6 has a dithiolene-fused tricyclic pyridone skeleton. The structures of 3, 5, 6, 8, and 11 were determined by X-ray diffraction studies. Intramolecular OH?N(²Py) hydrogen bondings are found in 5 and 8, and an intermolecular OH?N(⁴Py) one is found in 11 at solid state. In the 2-pyridonyl complex 3, intermolecular NH?O and CH(dithiolene)?O hydrogen bondings are observed. 8 showed an intermolecular Cp?Cp face-to-face interaction. The tricyclic complex 6 exhibited lower energy electronic absorption (λ_max = 668 nm) compared with the others (λ_max = 562-614 nm), due to an extended π-conjugation of aromatic cobaltadithiolene ring.     

Synthesis,Characterization and reactivities of Schiff-base complexes of Ruthenium(III)

Schiff-base complexes of ruthenium (1–5) have been synthesized using Schiff-base ligands derived by condensation of either 1,2-phenylenediamine with aldehydes (salicyldehyde, 2-pyridinecarboxaldehyde) or acetylacetone with amines (2-aminophenol, 2-aminomethylpyridine). All complexes were characterized by analytical, spectroscopic, conductance, magnetic moment and electrochemical studies. At room temperature, complexes 1–5 catalyze the oxidation of both saturated and unsaturated hydrocarbons using tert-butylhydroperoxide (t-BuOOH). A mechanism involving formation of and transfer from a reactive high valency Ru(V)-oxo species as the catalytic intermediate is proposed for the processes.     

Syntheses, structures, and physical properties of nickel bis(dithiolene) complexes containing tetrathiafulvalene (TTF) units

To contribute to the development of single-component molecular metals, several nickel complexes with cyclohexeno-condensed or ethylenedioxy-substituted TTF (tetrathiafulvalene) dithiolate ligands, (R(4)N)(n)[Ni(chdt)(2)] [R = Me, n = 2 (1); R = (n)Bu, n = 1 (2); n = 0 (3)] and (R(4)N)(n)[Ni(eodt)(2)] [R = Me, n = 2 (4); R = (n)Bu, n = 1 (5); n = 0 (6)], were prepared. X-ray structures were determined on the monoanionic species 2 and 5. The tetra-n-butylammonium complex of the monoanionic [Ni(chdt)(2)] (2) with a 1:1 composition revealed that its magnetic susceptibility gave a good agreement with the Bonner-Fisher model (J/k(B) = -28 K), which was derived from the one-dimensional chains of anions with a regular interval. On the other hand, the magnetic susceptibility of the tetra-n-butylammonium complex of the monoanionic [Ni(eodt)(2)] (5) showed the Curie-Weiss behavior (C = 0.376 K.emu.mol(-1) and Theta = -4.6 K). Both of the monoanionic species 2 and 5 indicate that they belong to the S = 1/2 magnetic system and have relatively large and anisotropic g-values, suggesting the contribution of the nickel 3d orbital. Electrical resistivity measurements were performed on the compressed pellets of the neutral species 3 and 6. Fairly large conductivities were obtained (sigma(rt) = 1-10 S.cm(-1)). In addition, despite the measurements on the compressed pellets of powder samples, the neutral species 6 showed metallic behavior down to ca. 120 K and retained high conductivity even at 0.6 K [sigma(0.6 K)/sigma(rt) approximately 1/30], suggesting the crystal to be essentially metallic down to very low temperature. The electrical behavior and Pauli paramagnetism of 6 indicate the system to be a new single-component metal.     

Syntheses,crystal structures and thermal behavior of three Mn(II) complexes with 4-acyl pyrazolone derivatives

Three new manganese complexes, [Mn(PPeAP-INH)(CH₃OH)₂]_n(CHCl₃) (1) [PPeAP-INH=N-(1-phenyl-3-phenylethyl-4-ethylene-5-pyrazolone isoniazid, INH = isoniazid], [Mn₂(PM4MbP-INH)₂(CH₃OH)₄](CH₃OH) (2·CH₃OH), [PM4MbP-INH=N-(1-phenyl-3-methyl-4-(p-methylbenzoylene)-5-pyrazolone) isoniazid)] and [Mn₂(PPePeP-INH)₂(CH₃OH)₄] (3) [PPePeP-INH=N-(1-phenyl-3-phenylethyl-4-phenylethylene-5-pyrazolone) isoniazid] have been prepared, aiming at the formation of extended coordination polymer with Mn(II) ions. Formation of the corresponding manganese-ligand complexes has been monitored and characterized by chemical and spectroscopic techniques. X-ray diffraction analyses of available single crystals revealed 1D polymeric patterns of supramolecular system. Among them, the dimers of 2 and 3, bridged by two methanol molecules, are extended by hydrogen bond of O–H···N to form the 1D chain. In these three new complexes which are all octahedral coordination environments, the N(5) atom of the pyridine heterocycles plays a very important role in building the bridged polymeric chain.     

Syntheses of new Mo(II) and W(II) mono(hydrosulfido) complexes and their conversion into di- and tetranuclear sulfido-bridged heterobimetallic complexes

Treatment of [Cp′MH(CO)₃] (M = Mo, W; Cp′ = η⁵-C₅H₅ (Cp), η⁵-C₅Me₅ (Cp*)) with 1/8 equiv of S₈ in THF, followed by the reaction with dppe under UV irradiation, gave new mono(hydrosulfido) complexes [Cp′M(SH)(CO)(dppe)] (Cp′ = Cp: M = Mo (5), W (6); Cp′ = Cp*: M = Mo (7), W (8); dppe = Ph₂PCH₂CH₂PPh₂). When 5 and 6 dissolved in THF were allowed to react with [RhCl(PPh₃)₃] in the presence of base, heterodinuclear complexes with bridging S and dppe ligands [CpM(CO)(μ-S)(μ-dppe)Rh(PPh₃)] (M = Mo (9), W(10)) were obtained. Semi-bridging feature of the CO ligands were also demonstrated. Upon standing in CH₂Cl₂ solutions, 9 and 10 were converted further to the dimerization products [(CpM)₂{Rh(dppe)}₂(μ₂-CO)₂(μ₃-S)₂] (M = Mo (13), W). Detailed structures of mononuclear 7 and 8, dinuclear 9 and tetranuclear 13 have been determined by the X-ray diffraction.     

Syntheses, structures and reactivities of diindenyl-coordinated diiron bridging carbene complexes

Compound [Fe₂(μ-CO)₂(CO)₂(η⁵-C₉H₇)₂] (1) reacts with aryllithium reagents, ArLi (Ar = C₆H₅, p-CH₃C₆H₄, p-CF₃C₆H₄) followed by alkylation with Et₃OBF₄ to give the diindenyl-coordinated diiron bridging alkoxycarbene complexes [Fe₂{μ-C(OC₂H₅)Ar}(μ-CO)(CO)₂(η⁵-C₉H₇)₂] (2, Ar = C₆H₅; 3, Ar = p-CH₃C₆H₄, 4, Ar = p-CF₃C₆H₄). Complex 4 reacts with HBF₄ · Et₂O at low temperature to yield cationic bridging carbyne complex [Fe₂(μ-CC₆H₄CF₃-p)(μ-CO)(CO)₂(η⁵-C₉H₇)₂]BF₄ (5). Cationic 5 reacts with NaBH₄ in THF at low temperature to afford diiron bridging arylcarbene complex [Fe₂{μ-C(H)C₆H₄CF₃-p}(μ-CO)(CO)₂(η⁵-C₉H₇)₂] (6). The reaction of 5 with NaSC₆H₄CH₃-p under the similar conditions gave the bridging arylthiocarbene complex [Fe₂{μ-C(C₆H₄CF₃-p)SC₆H₄CH₃-p}(μ-CO)(CO)₂(η⁵-C₉H₇)₂] (7). Complex 5 can also react with carbonylmetal anionic compounds Na[M(CO)₅(CN)] (M = Cr, Mo, W) to produce the diiron bridging aryl(penta-carbonylcyanometal)carbene complexes [Fe₂{μ-C(C₆H₄CF₃-p)NCM(CO)₅}(μ-CO)(CO)₂(η⁵-C₉H₇)₂] (8, M = Cr; 9, M = Mo; 10, M = W). The structures of complexes 4, 6, 7, and 10 have been established by X-ray diffraction studies.