Anionic Bis Research Articles

Phase equilibria of mixtures of mutually immiscible ionic liquids

In the last decade, the scientific community has witnessed a burgeoning research in ionic liquids. Numerous and diverse applications for them have been pointed out in the literature, with some processes based on ionic liquid technology already working in real plants. Among the possible fields of application, that of solvent extraction involving ionic liquids as solvents holds an important position. The opportunities of ionic liquids as alternative solvents for these kind of processes could be improved by the recent discovery of mutually immiscible ionic liquids. The use of ionic liquids presenting mutual immiscibility can generate stable multi-layer solvent systems, which, combined with the typical advantages offered by ionic liquids (good solvation properties, task-specific tuned structures, etc.), can mean a powerful medium for multi-component separations. To get a deeper knowledge of the behaviour of mutually immiscible ionic liquids, the phase equilibria of binary and ternary mixtures of ionic liquids were investigated. Specifically, hydrophobic ionic liquids with the common anion bis{(trifluoromethyl)sulfonyl}amide were selected. Pairs of ionic liquids with largely different cations were chosen, looking for the existence of mutual immiscibility between them. It was found that ionic liquids with a tetraalkylphosphonium cation are largely immiscible at ambient temperature with some other ionic liquids including 1,3-dialkylimidazolium or 1-alkylpyridinium cations. The miscibility of such pairs of ionic liquids was temperature dependent, following an upper critical solution temperature (UCST) behaviour. It was also found that small changes in the structure of an ionic liquid can drastically affect the mutual solubility with another ionic liquid. The liquid–liquid equlibrium (LLE) data of these systems were acceptably correlated by means of the classical non-random two-liquid (NRTL) equation.

Cerium(III) and Cerium(IV) Bis(η8-pentalene) Sandwich Complexes: Synthetic, Structural, Spectroscopic, and Theoretical Studies

The Ce(III) anionic bis(pentalene) sandwich complex K[Ce{C 8H4(SiiPr3-1,4)2} 2] (1) has been prepared by treatment of CeCl3 with K 2[C8H4(SiiPr3-1,4) 2] and crystallographically characterized as its 18-crown-6 complex. Oxidation of 1 with Ag[BPh4] affords the neutral, formally Ce(IV) sandwich complex [Ce{C8H4(SiiPr 3-1,4)2)2] (2), whose molecular structure has also been determined. The electronic structure of 2 has been investigated in detail by a combination of magnetic studies, K-edge XANES measurements, gas-phase photoelectron spectroscopy, and density functional calculations.

Using the crystal to engineer the molecule: cis-trans-isomer selection in anionic bis(orotate) complexes

Two chelating orotate2− ligands have been coordinated to the same metal ion, producing the first dianionic bis-orotate complex, [Ni(orotate)2(H2O)2]2−, whose geometric isomer can be selected by enabling or vitiating the formation of non-covalent interactions in the solid in which the product is isolated. This provides an important example of the influence and potential use of non-covalent interactions for isomer selection in the synthesis of coordination compounds, as well as the manner in which such stereochemical selection can be achieved by the appropriate use of counterions.

Synthesis and reactivities of a bis(cyanamido)-capped triruthenium complex

The tetraruthenium complex [Cp*RuCl]4 (Cp* = eta(5)-C(5)Me(5)) reacts with Na(2)NCN to afford the anionic bis(cyanamido)-capped triruthenium complex [(Cp*Ru)3(micro(3)-NCN)(2)]- ((2-)), which undergoes single electron oxidation to form [(Cp*Ru)3(micro(3)-NCN)2] upon workup with 1 equiv. of [Cp(2)Fe](PF(6)) (Cp = eta(5)-C(5)H(5)). Treatment of (2-) with 1 equiv. of HCl at room temperature leads to the protonation of one of the Ru-Ru edges to give the hydrido-bridged complex [(Cp*Ru)3(micro-H)(micro-NCN)2], while the cationic side-on NCNH(2) complex [(Cp*Ru)3(micro-Cl)(micro(3)-NCN)(micro(3)-NCNH(2)-1kappaC,N:2kappaC:3kappaN)]Cl (5) is obtained by the reaction of (2-) with an excess amount of HCl at -78 degrees C. On the other hand, the reaction of (2-) with BR(3) (R = Et, Ph) results in the ligation of two BR(3) molecules to the terminal nitrogen atoms of the cyanamido ligands to yield the bis(borane) adduct (PPN)[(Cp*Ru)(3){(micro(4)-NCN)(BR(3))}(2)] (6, PPN = Ph(3)PNPPPh(3)). 6b (R = Et) slowly liberates one BEt(3) molecule in acetone to give the mono(borane) adduct (PPN)[(Cp*Ru)3(micro(3)-NCN){(micro(4)-NCN)(BEt(3))}] (7). (2-) is also shown to react with [AuCl(PPh(3))] or PhCOCl to afford the tetranuclear heterometallic complex [(Cp*Ru)3(micro(3)-NCN){(micro(4)-NCN)(AuPPh(3))}] (8) or the benzoylcyanamido complex [(Cp*Ru)3(micro(3)-NCN)(micro(3)-NCNCOPh)] in which the Au(PPh(3))+ or benzoyl fragment is bound to the terminal nitrogen atom of a cyanamido ligand. The molecular structures of PPN+(2-), 5.C(6)H(6), 7 and 8.C(6)H(6) have been determined by single-crystal X-ray analyses.

Syntheses and properties of NCN-bridged tri- and tetranuclear complexes of cobalt and rhodium

The reaction of [Cp ∗CoI 2] 2 ( 1b) with 2 equiv of NaNCNH affords the 16-membered macrocyclic NCNH-bridged tetracobalt(III) complex [Cp ∗CoI(μ 2-NCNH- N, N′)] 4 ( 2b), while that with 2 equiv of Na 2NCN yields the C 3-elongated cubane-like NCN-bridged tetracobalt(III) complex [Cp ∗Co(μ 3-NCN- N, N, N′) 3(CoCp ∗) 3(μ 3-NCN- N, N, N)] ( 4b). Treatment of [Cp ∗RhCl 2] 2 ( 1c) with 2 equiv of NaNCNH gives the C 3-elongated cubane-like tetrarhodium(III) complex [Cp ∗Rh(μ 3-NCN- N, N, N′) 3(RhCp ∗) 3(μ 3-NCN- N, N, N)] ( 4c) via the macrocyclic complex [Cp ∗RhCl(μ 2-NCNH- N, N′)] 4 ( 2c). On the other hand, the reaction of [Cp ∗CoCl] 2 ( 7) with Na 2NCN affords the anionic bis(NCN)-capped tricobalt(II) complex Na[(Cp ∗Co) 3(μ 3-NCN- N, N, N) 2] ( 6). The molecular structures of complexes 2b · CH 2Cl 2 and 4c · 2C 6H 6 have been confirmed by X-ray analyses. The electrochemical properties of these types of NCN-bridged group 9 metal complexes have also been examined.

Tailoring of Horseradish Peroxidase Activity in Cationic Water-in-Oil Microemulsions

Horseradish peroxidase (HRP) in cationic water-in-oil (W/O) microemulsions has always been ignored in reverse micellar enzymology, mainly because cationic surfactants are inhibitors of enzyme peroxidase. In the present study, for the first time, we have successfully introduced the cationic W/O microemulsion as an attractive host for efficient HRP activity. To this notion, much improved activity of HRP was observed in the W/O microemulsion of cetyltrimethylammonium bromide (CTAB) with an increase in n-hexanol concentration and W0 ([water]/[surfactant]), presumably due to the increased interfacial area of the microemulsions. In support of our above observation, six surfactants were synthesized with an increased headgroup size where the methyl groups of CTAB were subsequently replaced by the n-propyl and 2-hydroxyethyl groups, respectively, to prepare mono-, di-, and tripropylated/hydroxyethylated n-hexadecylammonium bromide. The peroxidase activity enhanced with headgroup size and also followed an overall trend similar to that found in the case of CTAB. Possibly, the reduced positive charge density at the augmented interfacial area by means of increase, either in headgroup size, cosurfactant concentration, and/or W0, is not capable of inactivating HRP. Also, the larger space at the interface may facilitate easier solubilization of the enzyme and increase the local concentration of enzyme and substrate, leading to the higher activity of HRP. The best activity was obtained with surfactant N-hexadecyl-N,N,N-tripropylammonium bromide, the highest ever found in any cationic W/O microemulsions, being almost 3 times higher than that found in water. Strikingly, this observed highest activity is comparable with that observed in an anionic bis(2-ethylhexyl)sulfosuccinate sodium salt (AOT)-based system, the best W/O microemulsions used for HRP.

Complexes of a gallium heterocycle with transition metal dicyclopentadienyl and cyclopentadienylcarbonyl fragments, and with a dialkylmanganese compound

The reactivity of several transition metal half sandwich complexes towards an anionic gallium(I) heterocyclic complex, [K(tmeda)][Ga{[N(Ar)C(H)]2}](Ar = C6H3Pri2-2,6), has been investigated. This has led to the anionic half sandwich complexes, [K(tmeda)][(C5H4R)M(CO)n[Ga{[N(Ar)C(H)]2}]](M = V, R = H, n= 3; M = Mn, R = Me, n= 2; M = Co, R = H, n= 1), which crystallographic studies show to form dimers (M = Mn and Co) or a polymer (M = V) through bridging potassium cations. The metal-gallium bond lengths in all complexes are very short which, combined with some spectroscopic evidence, is suggestive of M-Ga pi-bonding. Density functional theory studies of models of all complexes indicate that the level of back-bonding in these complexes is, however, minimal and of a similar order to that seen in analogous complexes incorporating neutral N-heterocyclic carbene ligands. Reactions of the metallocenes, [M(C5H4Me)2](M = V or Cr), with the digallane4, [Ga{[N(Ar)C(H)]2}]2, have afforded the neutral complexes, [M(C5H4Me)2[Ga{[N(Ar)C(H)]2}]], which are thought to be formed via an initial oxidative insertion of the transition metal centre into the Ga-Ga bond of the digallane. X-Ray crystallography shows the complexes to be monomeric. One (M = V) reacts with one equivalent of [K(tmeda)][Ga{[N(Ar)C(H)]2}] to give the crystallographically characterised, anionic bis(gallyl)-complex, [K(tmeda)][V(C5H4Me)2[Ga{[N(Ar)C(H)]2}]2]. For comparison, the reaction of [K(tmeda)][Ga{[N(Ar)C(H)]2}] with [Mn{CH(SiMe3)2}2] was carried out and gave the monomeric, anionic complex, [K(tmeda)][Mn{CH(SiMe3)2}2[Ga{[N(Ar)C(H)]2}]].

Salinity Controlled Vesicle Formation and Growth in Aqueous Mixture of Aerosol OT/Triton X‐100

Mixed vesicles can be formed spontaneously from aqueous mixture of the double‐tailed anionic surfactant sodium bis(2‐ethylhexyl) sulfosuccinate (AOT) and the nonionic surfactant octylphenoxypolyethoxyethanol (Triton X‐100) under the inducement of salt, the formation mechanism of which should be attributed to the compression of salt on the electric bilayers of the head groups. The stability and the polydispersity of the vesicles are superior to single‐component AOT vesicles, which can be proved by the TEM image and visual observation. The vesicle region was presented in a pseudo‐ternary diagram of AOT/TX‐100/brine. The size of the vesicle was measured using dynamic light scattering. It is found that the vesicle size increases with the salinity but decreases with the content of TX‐100 in the mixture at the same salinity. Especially, the vesicle size is independent of the surfactant concentration at fixed salinity.

New triorganotin(IV) complexes of a polyfunctional S, N, O-ligand

The new sodium bis(2-pyridylthio)acetate ligand, Na[(pyS) 2CHCO 2], has been prepared in ethanol solution using 2-mercaptopyridine, dibromoacetic acid and NaOH. New tri-organotin(IV) derivatives containing the anionic bis(2-pyridylthio)acetate have been synthesized from reaction between SnR 3Cl (R = Me, n Bu, Ph and Cy) acceptors and Na[(pyS) 2CHCO 2]. Complexes of the type {[(pyS) 2CHCO 2]SnR 3}have been obtained and characterized by elemental analyses, FT-IR, ESI-MS, multinuclear ( 1H and 119Sn) NMR spectral data and X-ray crystallography. Crystallisation of the compound {[(pyS) 2CHCO 2]Sn(CH 3) 3} n , from chloroform/diethyl ether solution, yielded the complex {[(pyS) 2CHCO 2]Sn(CH 3) 3} n · CHCl 3, which has been characterized by X-ray crystallography.

Synthesis and spectroscopic characterization of new organotin(IV) complexes with bis(3,5-dimethylpyrazol-1-yl)dithioacetate

New organotin(IV) derivatives containing the anionic ligand bis(3,5-dimethylpyrazolyl)dithioacetate [L2CS2]− have been synthesized by reaction of SnR n X4− n (R = Me, Ph, n Bu or Cy; n = 1–3) acceptors and Li[L2CS2]. Mononuclear complexes of the type [L2CS2]R n SnCl4− n −1} have been obtained and fully characterized by elemental analyses and FT-IR in the solid state, and by NMR (1H and 119Sn) spectroscopy, conductivity measurements and electrospray ionization mass spectrometry (ESI-MS) in solution. ESI-MS spectra of methanol solutions of diorganotin derivatives, recorded with fragmentor potentials of 0, 50, 100 and 150 V, show the occurrence at 150 V of peaks attributable to the loss of the CS2 group from the ligands and the formation of stable tetraorganodistannoxane species.

Synthesis, spectroscopic characterization (IR,1H,13C and119Sn NMR, electrospray mass spectrometry) and toxicity of new organotin(IV) complexes withN,N′,O- andN,N′,S-scorpionate ligands

New organotin(IV) derivatives containing the anionic ligands bis(3,5-dimethylpyrazol-1-yl)dithioacetate [LCS 2 ] - and bis(3,5-dimethylpyrazol-1-yl)acetate [LCO 2 ] - have been synthesized from reaction between (CH 3 ) 2 SnCl 2 and lithium salts of the ligands. Mononuclear complexes of the type {[LCX 2 ](CH 3 ) 2 SnCl} (X = S or O) have been obtained and fully characterized by elemental analyses and FT-IR in the solid state and by NMR ( 1 H, 13 C and 119 Sn) spectroscopy, conductivity measurements and electrospray ionization mass spectrometry in solution. The acute toxicity of new organotin(IV) derivatives on rat was studied, comparing their effect with those of dimethyltin chloride (CH 3 ) 2 SnCl 2 . The comparison of LD 50 of organotin(IV) complexes and (CH 3 ) 2 SnCl 2 administered intraperitoneally, as a single dose, evaluated in vivo on rats, showed that toxicity decreases as follows: (CH 3 ) 2 SnCl 2 > LCO 2 > LCS 2 . The effect of these organotin(IV) complexes on DNA was evaluated in vitro and in vivo on rats treated with different doses of these compounds (1/20 LD 50 and 1/100 LD 50 ). The lymphocyte DNA status was assessed by the comet assay, a rapid and sensitive single-cell electrophoresis technique, used to detect primary DNA damage in individual cells. After 36 h from the start of treatment the two new organotin(IV) derivatives induced a significant rise in comet assay parameters, indicating an increasing presence of damaged DNA.

Electrochemical Stability and Lithium Ion-Anion Interactions of Orthoborate Anions (BOB, MOB, BMB), and Presentation of a Novel Anion: Tris-oxalato-phosphate

Ab initio calculations reveal the extraordinary low lithium ion affinities of the orthoborate anions bis(oxalate)borate (BOB), malonato-oxalatoborate (MOB), and bis(malonato)borate (BMB). HF and MP2 calculations reveal these anions to be less prone to associate with Li + (by ∼10%) than most anions used today, e.g., PF 6 - , BF 4 - , and TFSI, in low dielectric media such as polymeric electrolytes. Furthermore, by using self-consistent reaction field calculations to model the effect of high dielectric solvents present, the applicability of these anions also for liquid and gel electrolytes was proven. Future directions of lithium salt synthesis are outlined and exemplified by a new anion, suggested here for the first time. The HOMO levels of the anions are correlated to electrochemical stabilities in electrolytic solutions; all studied anions can be anticipated to have wide stability ranges. Finally, a new methodology to obtain starting data for geometry optimizations of cation-anion pairs by global optimization is presented. © 2005 The Electrochemical Society. All rights reserved.

Synthesis, characterization and hydrolytic behavior of new bis(2-pyridylthio)acetate ligand and related organotin(IV) complexes

The new sodium bis(2-pyridylthio)acetate ligand, Na[(pyS) 2CHCO 2], has been prepared in ethanol solution using 2-mercaptopyridine, dibromoacetic acid and NaOH. New mono- and di-organotin(IV) derivatives containing the anionic bis(2-pyridylthio)acetate have been synthesized from reaction between SnR n Cl 4− n (R = Me, Ph and n Bu, n = 1–2) acceptors and Na[(pyS) 2CHCO 2]. Mono-nuclear complexes of the type {[(pyS) 2CHCO 2]R n SnCl 4− n−1 } have been obtained and characterized by elemental analyses, FT-IR, ESI-MS, multinuclear ( 1H and 119Sn) NMR spectral data and X-ray crystallography. ESI-MS spectra of methanol solution of the complexes show the existence of hydrolysed species. Attempts to crystallize the dimethyltin(IV) derivative ( 3), from acetonitrile solution yield the dimeric dicarboxylatotetramethyldistannoxane ( 8), which was characterized by single crystal diffraction analysis.

Silver(I) bis(1,2,4-triazolyl)borate complexes containing bidentate phosphine ligands

New silver(I) derivatives containing bidentate phosphine and anionic bis(triazol-1-yl)borate ligands have been prepared from the reaction of AgNO 3 and dppm (bis(diphenylphosphino)methane), dppe (1,2-bis(diphenylphosphino)ethane), or dppf (1,1′-bis(diphenylphosphino)ferrocene) and potassium dihydrobis(1,2,4-triazolyl)borate, K[H 2B(tz) 2]; their solid state and solution properties have been investigated through analytical and spectroscopic measurements (IR, 1H and 31P NMR). All the compounds are soluble in chlorinated solvents and are non-electrolytes in CH 2Cl 2 and acetone solutions. [{H 2B(tz) 2}Ag(dppf)] is simple mononuclear array, the silver atom lying in four-coordinate N 2AgP 2 environment. In [{H 2B(tz) 2} 2Ag 3(dppm) 2(NO 3)], the silver environment is still four-coordinate but PAgN 3, utilizing the coordinating capability of one of the additional (‘exo’-) ring nitrogens not only to complete the four-coordinate array about the silver but, necessarily, to link successive asymmetric units into a single-stranded polymer. [{H 2B(tz) 2} 2Ag 3(dppm) 2(NO 3)] may be regarded as a hemi-adduct of [{H 2B(tz) 2}Ag(dppm)] with silver(I) nitrate, thus [{H 2B(tz) 2}Ag(dppm)]: AgNO 3 (2:1).

Bis(pyrazolyl)(thioimidazolyl)borate Ligands: The Missing Member in the N3···S3 Scorpionate Series

The anionic bis(pyrazolyl)(thioimidazolyl)borate ligands BpMt(R) with R = tert-butyl and isopropyl were obtained as their potassium salts by reacting potassium tris(pyrazolyl)borate with the corresponding thioimidazoles in the melt at 150 degrees C. They were applied to form some tetrahedral zinc complexes and identified by the crystal structures of (BpMt(t-Bu))ZnCl and (BpMt(i-Pr))Zn-SC(6)H(4)-p-Cl.

Reaction of Bis(2,4-dinitrophenyl) Phosphate with Hydrazine and Hydrogen Peroxide. Comparison of O- and N- Phosphorylation

Nonionic hydrazine reacts with anionic bis(2,4-dinitrophenyl) phosphate (BDNPP), giving 2,4-dinitrophenyl hydrazine and dianionic 2,4-dinitrophenyl phosphate by an S(N)2(Ar) reaction, and at the phosphoryl center, giving 2,4-dinitrophenoxide ion and a transient phosphorylated hydrazine that rearranges intramolecularly to N-(2,4-dinitrophenyl)-N-phosphonohydrazine. Approximately 58% of the reaction at pD = 10 occurs by N-phosphorylation, as shown by (31)P NMR spectroscopy. Reaction of HO(2)(-) is wholly at phosphorus, and the intermediate peroxophosphate reacts intramolecularly, displacing a second 2,4-dinitrophenoxide ion, or with H(2)O(2), giving 2,4-dinitrophenyl phosphate and O(2). Rate constants of O- and N-phosphorylation in reactions at phosphorus of NH(2)NH(2), HO(2)(-), and NH(2)OH and its methyl derivatives follow Bronsted relationships with similar slopes, but plots differ for oxygen and nitrogen nucleophiles. The reaction with NH(2)NH(2) has been probed by using both NMR spectroscopy and electrospray ionization mass and tandem mass spectrometry, with the novel interception of key reaction intermediates in the course of reaction.

Effect of reactive dyes upon the uptake and antibacterial action of poly(hexamethylene biguanide) on cotton. Part 1: Effect of bis(monochlorotriazinyl) dyes

Poly(hexamethylene biguanide) (PHMB) is of interest as a bactericide for fabrics. It has affinity for cotton by reaction with the cellulosic carboxylate groups. In this study, the capacity of undyed cotton to absorb PHMB has been determined and compared with cotton dyed with anionic bis(monochlorotriazinyl) reactive dyes. When cotton is dyed with these dyes the absorption of PHMB increases, the dye providing sulphonic acid sites with which the PHMB can react. The reacted PHMB and the percentage fixation of reactive dye were determined and from this the concentration of sulphonic acid on the dyed fibre. In the case of cotton dyed with Procion Yellow H‐E4R, the dye increased the absorption of PHMB to approximately 1.45 mequiv. of biguanide per sulphonic acid group. For Procion Red H‐E3B and Navy H‐ER the figures were 1.18 and 1.00, respectively.

Mononuclear Lanthanide Complexes with a Long Magnetization Relaxation Time at High Temperatures: A New Category of Magnets at the Single-Molecular Level

Alternating current (ac) magnetic susceptibility and magnetization hysteresis loop measurements have been carried out for anionic bis(phthalocyaninato)terbium and bis(phthalocyaninato)dysprosium. The two mononuclear lanthanide complexes show the characteristic temperature and frequency dependence in the ac susceptibility signals, reflecting their slow magnetization relaxation. From the Arrhenius analysis of the ac susceptibility data obtained for a diluted sample in a diamagnetic matrix, it has been found that the magnetization relaxation in the Tb complex is dominated by the two-phonon Orbach process in the temperature range 25−40 K and direct or Raman process below 25 K. In the Dy complex case, the Orbach process is the main relaxation process in the range 3−12 K. The Δ values in the Orbach term, corresponding to the height of the potential energy barrier to magnetic moment reversal, are in good agreement with the energy differences between the lowest and second lowest substates of the ground multiplet in the two cases. In the magnetization−field (M−H) loop measurements at 1.7 K, clear hysteresis has been observed for both complexes. These results indicate that the two double-decker phthalocyanine−lanthanide complexes behave as magnets at the single-molecular level. They are the first lanthanide compounds as well as the first mononuclear complexes showing such behaviors. Differences in the magnetization relaxation mechanism between the new “mononuclear lanthanide magnets” and the transition-metal-cluster-based SMMs (single-molecule magnets) are discussed.

Synthesis and characterization of two pentanuclear complexes (NEt 4) 2[MS 4(CuBp) 4] (M=Mo, W; Bp=H 2B(pyrazolyl) 2) and crystal structure determination of (NEt 4) 2[WS 4(CuBp) 4

Two new copper(I) complexes containing the [MS 4] 2− core (M=Mo or W) and anionic bis(pyrazolyl)borate (Bp) ligands have been prepared from the reactions of (Et 4N) 2[MS 4], CuCl and KBp. In addition to elemental analysis, their IR, UV–Vis, 1H and 13C NMR spectra have been studied. The structure of (NEt 4) 2[WS 4(CuBp) 4] has been determined by single-crystal X-ray diffraction. In the pentanuclear dianion, [WS 4(CuBp) 4] 2−, which has crystallographic S 4 symmetry, the coordination environment around each copper atom is distorted tetrahedral, with two N donors of the bidentate Bp ligands and two S donors of the WS 4 core, representing a structural model for some copper proteins. The W atom retains the tetrahedral geometry of the free [WS 4] 2− anion.

The First Luminescent Anionic Bis(ethynylphenanthroline)gold(I) Complex

Abstract First anionic bis(ethynylphenanthroline)gold(I) complex and neutral diethynylphenanthroline–digold(I) complex have demonstrated an intense phosphorescence which is assignable to 3π–π*(C≡C) emission even at room temperature. It is appropriate to highlight the role of gold(I) coordination which enables the spin–orbit coupling and facilitates the observation of triplet emissions.