Synthesis of poly(<Emphasis Type="Italic">p</Emphasis>-phenyleneethynylene)s bearing oligo-ethylene glycols and their gas permeation properties

1,4-Diiodobenzenes bearing oligo-ethylene glycols [IRC₆H₂IR, R = OCH₂CH₂OCH₃ (1a), O(CH₂CH₂O)₂CH₃ (1b), O(CH₂CH₂O)₃CH₃ (1c)] were polymerized with 1,4-diethynylbenzene in the presence of Pd/Cu catalyst to afford poly(p-phenyleneethynylene)s bearing oligo-ethylene glycols (2a–c), respectively. Polymer 2a was insoluble in any solvents, but the other polymers (2b, 2c) were soluble in CHCl₃. The weight-average molecular weights of 2b and 2c were 5.4 × 10⁴ and 9.6 × 10⁴, respectively, and they gave free-standing membranes by solution-casting method. The densities of membranes of 2b and 2c were 1.26 and 1.22 g/cm³, respectively, and their carbon dioxide permeability coefficients were 12.9 and 13.5 barrers, respectively. The CO₂/N₂ separation factor of membrane of 2b was as large as 33.7. Membrane of 3b, which contains triethylene glycols, exhibited higher CO₂ permselectivity, and the CO₂/N₂ separation factor was 50.0.     

Synthesis, Properties, and Functionalization of Poly(ferrocenylsilane)s with Chloroalkyl Side Chains

A series of poly(ferrocenylsilane)s containing chloroalkyl side chains of increasing length is reported. By reacting fcLi₂· tmeda with Cl₂SiMeR, the corresponding [1]ferrocenophanes were prepared (2a, R=CH₂Cl; 2b, R=CH₂CH₂Cl; and 2c, R=CH₂CH₂CH₂Cl). Transition metal-catalyzed or thermal ring-opening polymerization (ROP) of these monomers yielded the polyferrocenes 3a, 3b, and 3c. The chlorine substituents of polymers 3a and 3b were unreactive toward nucleophilic substitution. In contast, polymer 3c could be reacted with 4-dimethylaminopyridine in DMF to afford the water-soluble poly(ferrocenylsilane) 4. This represents a new method for the preparation of water-soluble polyferrocenes.     

Chemical transformations of functional polycarbosilanes

The functional polycarbosilane [Si(X ₂)C₂H₄] _n , whereX ₂=Cl₂ (1), was chemically transformed into the corresponding polymers, whereX ₂=F₂ (3), (2-N, N-dimethylbenzylamino)(H) (5), (9-N,N-dimethyl-1-naphthylamino)(H) (6), (1-C₁₀H₇)(H) (7), Me₂ (8a), (Me₃SiNH)₂ (10), and (vinyl)(H) (11). The functional polycarbosilane, whereX ₂=H₂ (2), was converted into the polymers, whereX ₂=Me(H) (8b) and (OMe)₂ (9). Reaction of3 with KF in the presence of 18-crown-6 gave rise to the poycarbosilane4 containing both pentacoordinate and tetracoordinate silicons in the proportion of 1:15 as shown by quantitative¹⁹F and²⁹Si NMR. Conversion of a greater proportion of silicon atoms to the pentacoordinate state was not possible because of insolubility of the resulting ionomer in the reaction medium.     

Synthesis and characterization of new optically active poly(amide-imide)s containing 1,3,4-oxadiazole moiety in the main chain

Six new optically active poly(amide-imide)s were synthesized by poly condensation reaction of 2,5-bis(4-aminophenyl)-1,3,4-oxadiazole (8) with six chiral N,N′-(bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic)-bis-l-amino acids (3a–f) in a medium consisting of N-methyl-2-pyrrolidone (NMP), triphenylphosphite (TPP), calcium chloride (CaCl₂), and pyridine. Chiral N,N′-(bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic)-bis-l-amino acids (3a–f) were obtained by the reaction of bicyclo[2.2.2]-oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (1) with two equimolar of l-alanine (2a), l-valine (2b), l-leucine (2c), l-isoleucine (2d), l-phenyl alanine (2e), and l-2-aminobutyric acid (2f) in acetic acid. The poly condensation reaction produced a series of novel poly(amide-imide)s (9a–f) in high yield and with inherent viscosities between 0.30 and 0.52 dL/g. The resulting polymers were characterized by elemental analysis, viscosity measurement, solubility testing, thermo-gravimetric analysis (TGA), ¹H-NMR, and FT-IR techniques.     

Synthesis and gas permeability of poly(<Emphasis Type="Italic">p</Emphasis>-phenyleneethynylene)s having bulky alkoxy or alkyl groups

Dipropynylbenzene with branched alkoxy and alkyl groups [CH₃C≡CRC₆H₂RC≡CCH₃, R = 2-methylpropoxy (1a), 3-methylbutoxy (1b), 4-methylpentoxy (1c), cyclohexylmethoxy (1d), 2-ethylhexoxy (1e), 2-octoxy (1f), 2-ethylhexyl (1g), and 2-octyl (1h)] were polymerized with Mo(CO)₆ in the presence of 4-(trifluoromethyl)phenyl to afford poly(2,5-di(alkoxy or alkyl)-p-phenyleneethynylene)s (2a–h). Polymer 2a was insoluble in any solvents, but the other polymers (2b–h) were soluble in common organic solvents. The polymers with relatively long side chains (2e–h) had high molecular weight over 1.6 × 10⁴ and gave free-standing membranes by solution-casting method. The densities of membranes of 2e–h were 0.914–0.998, and their fractional-free volume values were relatively large (0.094–0.158). The oxygen permeability coefficients of membranes of 2e–h were 18.4, 12.7, 4.85, and 19.3 barrers, respectively. It was found that poly(p-phenyleneethynylene) with 2-octyl side groups, which have the branch at the nearest position from main chain, exhibited the highest gas permeability.     

Stereoselective synthesis of trans N/O dispirocyclic cyclotriphosphazenes based on the steric demands of the constrained 2-pyridyl group

Monospiro- and dispirocyclic cyclotriphosphazenes, 2a and 2b, were synthesized by the reaction of hexachlorocyclotriphosphazene, N₃P₃Cl₆ (1), with 2-(2-pyridylamino)phenol in the presence of base. The reactions of phosphazenes 2a and 2b with sodium (4-methyl-2-pyridyl)oxide afforded tetrakis- and bis(4-methyl-2-pyridyloxy)cyclotriphosphazenes, 3a and 3b, respectively. ³¹P NMR spectroscopy of 2b and 3b using d-camphorsulfonic acid as a chiral solvating agent indicated that they were racemates of the trans isomers. The trans configuration of trans-3b could also be elucidated by X-ray crystal structural analysis, which suggested that the steric demand of the 2-pyridyl group was responsible for the stereoselective formation of trans-2b. The steric demand of the 2-pyridyl group was supported by the reaction of N₃P₃Cl₆ (1) with N,N′-bis(2-pyridyl)benzene-1,2-diamine, which only gave monospirocyclic cyclotriphosphazene 4a.     

Synthesis and characterization of per-substituted spermine-bridged cyclophosphazene derivatives: the first example of syn/anti conformational polymorphism in a bridged cyclophosphazene

The synthesis and characterization of a series of per-substituted spermine-bridged cyclophosphazene derivatives are reported based on the known compound [N₃P₃X₄(NHCH₂CH₂CH₂N)CH₂CH₂]₂, (1a) (where X = Cl), to give a number of new compounds (1b–1h) in which X = OPh, [spiro-O(CH₂)₃O]_0.5, OCH₂CF₃, NHPh, NC₄H₈, Ph and NHBu^t, respectively. Two synthetic routes were utilized: (i) using the chloro-precursor 1a in nucleophilic substitution reactions with a variety of anionic and neutral nucleophiles to give compounds 1b–1f and (ii) reaction of spermine with the appropriate di-gem tetrasubstituted cyclophosphazene to give compounds 1g and 1h. Bridged compounds such as 1a–1h may exist as syn or anti conformers in the solid state and the first example of syn and anti conformational polymorphism is reported for a bridged cyclophosphazene, viz. for compound 1a.     

Enantiospecific Effect of Pulegone and Pulegone-Derived Lactones on Myzus persicae (Sulz.) Settling and Feeding

The effect of pulegone chiral center configuration on its antifeedant activity to Myzus persicae was examined. Biological consequences of structural modifications of (R)-(+)- and (S)-(−)-pulegone, the lactonization, iodolactonization, and incorporation of hydroxyl and carbonyl groups were studied, as well. The most active compounds were (R)-(+)-pulegone (1a) and δ-hydroxy-γ-spirolactones (5S,6R,8S)-(−)-6-hydroxy-4,4,8-trimethyl-1-oxaspiro[4.5]decan-2-one (5b) and (5R,6S,8S)-6-hydroxy-4,4,8-trimethyl-1-oxaspiro[4.5]decan-2-one (6b) derived from (S)-(−)-pulegone (1b). The compounds deterred aphid probing and feeding at preingestional, ingestional, and postingestional phases of feeding. The preingestional effect of (R)-(+)-pulegone (1a) was manifested as difficulty in finding and reaching the phloem (i.e., prolonged time preceding the first contact with phloem vessels), a high proportion of probes not reaching beyond the mesophyll layer before first phloem phase, and/or failure to find sieve elements by 20% of aphids during the 8-hr experiment. The ingestional activity of (R)-(+)-pulegone (1a) and hydroxylactones 5b and 6b resulted in a decrease in duration of phloem sap ingestion, a decrease in the proportion of aphids with sustained sap ingestion, and an increase in the proportion of aphid salivation in phloem. δ-Keto-γ-spirolactone (5R,8S)-(−)-4,4,8-trimethyl-1-oxaspiro[4.5]decan-2,6-dione (8b) produced a weak ingestional effect (shortened phloem phase). The postingestional deterrence of (R)-(+)-pulegone (1a) and δ-hydroxy-γ-spirolactones (5R,6S,8R)-(+)-6-hydroxy-4,4,8-trimethyl-1-oxaspiro[4.5]-decan-2-one (5a), 5b, (5S,6R,8R)-6-hydroxy-4,4,8-trimethyl-1-oxaspiro[4.5]decan-2-one (6a), 6b, and δ-keto-γ-spirolactone 8b prevented aphids from settling on treated leaves. The trans position of methyl group CH₃–8 and the bond C5–O1 in lactone 6b appeared to weaken the deterrent activity in relation to the cis diastereoisomer (5b).     

Reactions and products revealed by NMR spectra of deuterated dimethylsulfoxide with iodomethane in neutral and basic media

Reactions occurring within each one of two mixtures, a mixture of deuterated dimethylsulfoxide, DMSO-d₆, with CH₃I (system I) and another mixture of DMSO-d₆ with CH₃I, NaOH and water (system II), were monitored by 1D and 2D nuclear magnetic resonance (¹H, ¹³C, heteronuclear multiple quantum correlation, heteronuclear multiple bond correlation and diffusion-ordered NMR spectroscopy). The analysis of the spectra as a function of reaction time revealed the formation of methoxy-bis(trideuteromethyl)sulfonium iodide, 3; the precipitation of hexadeuterated trimethyloxosulfonium, 2a; a methyl exchange between DMSO-d₆ and 2a to produce trideuterated dimethylsulfoxide, DMSO-d₃, 4, and nona-deuterated trimethyloxosulfonium iodide, 2b; and the production of small quantities of methanol, 5, trideuterated dimethylsulfide, 6, and dimethyl ether, 7, in both systems. Only system II precipitated deuterated [Na₄(DMSO-d_x)₁₅][(I₃)₃I], 1a, a green solid with metallic shine that corresponds to an isotopomer of 1, which is produced by the self-assembly of DMSO and CH₃I in the presence of NaOH and water.     

A cis-directing effect towards diols by an exocyclic P-NHR moiety in cyclotriphosphazenes

Cyclophosphazenes containing the P-NHR moiety in an exocyclic spiro ring, N₃P₃Cl₄[NH(CH₂)₃O], (1), and N₃P₃Cl₄[NH(CH₂)₃NMe], (2), were used to investigate a possible directing effect of the P-NHR moiety on the formation of products in the nucleophilic substitution reactions with diols such as tetraethyleneglycol, 1,3-propanediol and 2,2-dimethyl-1,3-propanediol. The ³¹P NMR spectra of the reaction mixtures showed that only one kind of ansa product is formed in each of these reactions. X-ray crystallographic studies of the ansa products [(4a), (5a), (6a) and (7a)] have provided definitive proof of the cis-directing effect of the P-NHR moiety in cyclotriphosphazenes. It is likely that hydrogen-bond interaction between the incoming nucleophile and the P-NHR moiety of the reactant accounts for the preference for products with the substituents cis to the NH group.     

N-halosuccinimide-mercaptoethanol cohalogenation of olefinic fatty methyl esters: Synthesis of β-halo thioethoxylates

Olefinic fatty methyl esters, undec-10-enoate (1), octadec-Z-9-enoate (2), methyl-12 hydroxy octadec-Z-9-enoate (3), on reaction with N-halosuccinimides (4,5), that is, N-bromosuccinimide (4) or N-chlorosuccinimide (5) and 2-mercaptoethanol (6) in benzene, gave β-bromo- or β-chlorothioethoxylates (8–13). β-Halothioethoxylates so formed were acetylated with acetyl chloride in CH₂Cl₂ to form the respective acetylated products (20–25).     

Electrochemical study of β-diketonatobis(triphenylphosphite)rhodium(I) complexes

The electrochemical behaviour of the series of ten [Rh(RCOCHCOR′)(P(OPh)₃)₂] complexes with R, R′ = CF₃, CF₃ (1), CF₃, CH₃ (2), CF₃, Ph (C₆H₅) (3), CF₃, Fc (ferrocenyl = (C₅H₅)Fe(C₅H₄)) (4), CH₃, Ph (5), CH₃, CH₃ (6), Ph, Ph (7), Fc, CH₃ (8), Fc, Ph (9) and Fc, Fc (10) were studied in acetonitrile containing 0.100 mol dm⁻³ tetra-n-butylammonium hexafluorophosphate as supporting electrolyte utilizing a glassy carbon working electrode. Results are consistent with Rh(I) being first oxidized in an electrochemically irreversible two-electron transfer process at peak anodic potentials ranging E_pa(Rh) = 0.124–0.881 V vs. Fc/Fc⁺. For the ferrocene-containing complexes (4), and (8)–(10) the rhodium oxidation was followed by the electrochemically reversible oxidation of the ferrocenyl group in a one-electron transfer process at a slightly more positive potential. Relationships were established between the electrochemical quantity E_pa(Rh) and kinetic parameter log k₂ as well the sum of experimental group electronegativities (Gordy Scale) of the R and R′ groups (χ_R + χ_R′), the Hammett σ values (σ_R + σ_R′) and the Lever ligand parameter E_L for the [Rh(RCOCHCOR′)(P(OPh)₃)₂] complexes: E_pa(Rh) (vs. Fc/Fc⁺/V) = 0.31 (χ_R + χ_R′)–1.09 = 0.56 (σ_R + σ_R′) + 0.28 = S_M (ΣE_L) + (I_M − 0.66 V) = −0.23 log k₂ − 0.03 (k₂ = second order rate constant for the oxidative addition of methyl iodide to rhodium). A profound shift of E_pa(Rh) to a more positive potential was observed for Rh(I) substrates containing β-diketonato ligands with increasing electronegative substituents R and R′. An exponential dependence of E_pa(Rh) on the pK_a of the β-diketone was obtained.     

Organometallic–Inorganic Conjugated Unsymmetrical Schiff-Base Hybrids. Synthesis,Characterization, Electrochemistry and X-ray Crystal Structures of Functionalized Trinuclear Iron–Nickel–Ruthenium Dipolar Chromophores

The synthesis of neutral dinuclear iron–nickel unsymmetrical Schiff base complexes 3 and 4 was achieved via a template reaction involving equimolar amounts of alkyl or aryl “half-unit” precursors, respectively, Fc–C(O)CH=C(CH₃)N(H)R (1: R = CH₂CH₂NH₂; 2: R = o-C₆H₄NH₂; Fc = CpFe(η⁵-C₅H₄); Cp = η⁵-C₅H₅), 5-bromosalicylaldehyde and nickel(II) acetate tetrahydrate in a refluxing CH₂Cl₂/MeOH (1:1) mixture. The ionic trinuclear unsymmetrical complex 5 was prepared by reacting its dinuclear precursor 3 with the arenophile source, [Cp*Ru(NCCH₃)₃]PF₆ (Cp* = η⁵-C₅(CH₃)₅), in refluxing CH₂Cl₂ for 2 h, whereas the trinuclear species 6 was formed upon regioselective π-complexation of the 5-bromosalicylidene ring of 4 by [Cp*Ru]⁺ at room temperature overnight. All the new compounds were adequately characterized by analytical and spectroscopic techniques and, in addition, the crystal and molecular structures of the “half-unit” 1, the binuclear complex 4 and its hemisolvate adduct 4 · 0.5CH₃OH, the trinuclear Schiff base compound 5 · 2(CH₃)₂CO, and the mixed sandwich metalloligand 7 have been determined by X-ray crystallography. Both organometallic–inorganic hybrids 5 and 6 contain the neutral electron-releasing ferrocenyl group, and the cationic electron-withdrawing ruthenium mixed sandwich, linked through the unsymmetrical tetradentate Schiff base complex {Ni(ONNO)}. UV–vis, ¹H and ¹³C NMR as well as electrochemical data clearly indicate a mutual donor–acceptor electronic influence between the organometallic termini. Furthermore, X-ray crystal structure analysis of 5 · 2(CH₃)₂CO reveals the partial delocalization of bonding electron density throughout the dinucleating nickel Schiff base ligand. Dedicated to Prof. Didier Astruc, a true friend, an outstanding lecturer and scientist, in honor of his pioneering research efforts and accomplishments in the fields of organometallic chemistry, dendrimers and their applications in nanocatalysis.     

Synthesis of new fluorine containing ring-opened polynorbornene dicarboximides using ruthenium alkylidene catalysts

Summary  The synthesis of new N-4-trifluoromethylphenyl-exo-endo-norbornene-5,6-dicarboximide (TFmNDI, 2a) and N-3,5-difluorophenyl-exo-endo-norbornene-5,6-dicarboximide (DFNDI, 2b) was carried out. Polynorbornene dicarboximides, 3a and 3b, were obtained via ring opening metathesis polymerization (ROMP) using bis(tricyclohexylphosphine) benzylidene ruthenium(IV) dichloride (I) and tricyclohexylphosphine [1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene][benzylidene] ruthenium dichloride (II), respectively. T_g’s for polymers 3a and 3b were observed at 155 C and 142 C, respectively. Compared to polymer 3b, polymer 3a with the bulky trifluoromethyl group showed the highest glass transition temperature and improved mechanical properties.     

Ring-opening polymerization of various oxirane derivatives using organotin phosphate condensate; Selective synthesis of the polyether containing oxirane ring in the side chain

Ring-opening polymerization (ROP) of various oxirane derivatives of the type, 2,2-R¹,R²-CCH₂O [R¹ = H (1), CH₃ (2); R² = CH₃ (a), CH₂Cl (b), CH₂OCH₃ (c)], using organotin phosphate (Bu₂SnO-Bu₃PO₄) condensate has been explored. The ROP of monosubstituted oxiranes (1a-c) afforded ring-opened polymers in high yields (1a, 1c = 99% and 1b = 69%); the resultant polymers from monomers 1a and 1b possessed high molecular weights (M_n = 9.49 × 10⁴, 10.60 × 10⁴, respectively). In contrast, both polymer yields and molecular weights for resultant polymers in the polymerization of disubstituted oxiranes (2a-c) were considerably lower than those in the polymerization of monosubstituted monomers (1a-c). ROP of glycidyl 2-methylglycidyl ether (3) possessing two oxirane groups with different reactivity was thus conducted by organotin catalyst; the high molecular weight polyether (M_n = 9.17 × 10⁴) containing oxirane ring in the side chain has successfully been obtained in moderate yield.     

Anodic polarization behaviour of cast iron alloys in deaerated concentrated H3PO4 solutions containing Cl− and F− ions

The anodic behaviour of four cast iron alloys containing up to 16.7% Ni, in deaerated 60 wt% H₃PO₄ with and without 5 × 10^–3 M F^–, Cl^– ions and 1:1 Cl^–/F^– mixture was studied by the potentiostatic technique. Values of E _corr of the alloys are markedly influenced by their composition. The anodic behaviour in the active region is controlled by Fe in the alloys and the dissolution reaction is characterized by Tafel slopes, b _a, between 64 and 88 mV (decade)^–1. A two-electron transfer mechanism for the anodic dissolution is proposed. Passivation of the alloys is due to the formation of oxide layers including Fe₂O₃ and/or Fe₃O₄. Both critical and passive c.d. (I _cc and I _P) are markedly increased in the presence of Cl^– ions, but the presence of F^– ions inhibit the active dissolution of the alloys. The Tafel slope for oxygen evolution reaction (o.e.r.) in the transpassive region, is 240 ± 25 mV. In the proposed mechanism for the o.e.r., the rate determining step is an electron transfer reaction and possible interpretation of the high Tafel slopes is given based on the dual barrier model.     

Thermodynamic model for predicting phase equilibria of simple clathrate hydrates of refrigerants

In this communication, a thermodynamic model is presented for the study of the phase equilibria of clathrate hydrates of simple refrigerants. The van der Waals–Platteeuw solid solution theory is used to model the hydrate phase while it is assumed that vapor phase is an ideal gas of refrigerant ignoring its water content and the aqueous phase is considered as pure water (activity coefficient=1) ignoring aqueous solubility. The results through this model are successfully compared with the experimental data reported in the literature for clathrate hydrates of four refrigerants namely C₂H₂F₄ (1, 1, 1, 2-tetrafluoroethane or HFC-134a or R-134a), C₂H₄F₂ (1, 1-difluoroethane or HFC-152a or R-152a), CH₂F₂ (difluoromethane or HFC-32 or R-32), and C₂H₃Cl₂F (1,1-dichloro-1-fluoroethane or HCFC-141b or R-141b).     

Electrochemistry and spectro-electrochemistry of dithizonatophenylmercury(II)

The reactions between dithizone (H₂Dz, (1)) or potassium dithizonate (K⁺HDz⁻, (2)) and phenylmercury(II) chloride gives PhHg(HDz), (3). Complex (3) is photochromic. In dichloromethane, the blue photo-exited state of (3) exhibits a first order relaxation process to regenerate the orange ground state with rate constant 0.00053 s⁻¹. The half life of this relaxation is ca. 1300 s. Electrochemically, on cyclic voltammetry time scale, the oxidations of (1) and (3) are different. A comparative voltammetric and spectro-electrochemical study of (1) and (3) in CH₂Cl₂ containing 0.1 mol dm⁻³ [N(ⁿBu)₄][B(C₆F₅)₄] revealed that the mercapto group of (1) can be oxidised in two one-electron transfer steps. A disulphide is first produced and then in a second oxidation step, HDz⁺ is formed. In contrast, complex (3) shows only one ligand-based oxidation step. Upon complexation with phenylmercury the free mercaptan group of (1) becomes a stable “metal thioether”, Hg–S–C, which effectively prevents disulphide formation in (3) upon electrochemical oxidation. Both (1) and (3) shows two reduction steps. The electrochemical fingerprint of blue photo-excited (3) is identical to that of the orange ground state as no new functional groups are introduced upon irradiation; only bond rotation occurs. The different electronic spectra for each of the redox states of (3), obtained from spectro-electrochemical measurements, revealed that only the (3)/(3⁻) couple exhibits electrochromic properties.     

Ketene N,S-acetals in heterocyclic synthesis: Part 1: Synthesis of N-phenyl-2-ylidene and 2,5-diylidene-4-thiazolidinone derivatives

Ketene N,S-acetal potassium salts (2a–g), prepared via reaction of active methylenes (1a–g) with phenyl isothiocyanate in the presence of potassium hydroxide, were allowed to react with ethyl chloroacetate or chloroacetamide to afford the corresponding 2-ylidene-4-thiazolidinones (3a–g) in good yields. Compounds (3a–g) reacted with a variety of aromatic aldehydes to afford the corresponding 5-arylidene-2-ylidene-4-thiazolidinone derivatives (10a–e). Reaction of compound (3a) with triethylorthoformate afforded 5-ethoxymethylene-2-ylidene-4-thiazolidinone derivative (7), which was allowed to react with ammonia or phenyl hydrazine to give the corresponding enamino or hydrazino derivatives (8a) or (8b), respectively.     

Formation of an unusual copper(II) complex from the degradation of a novel tricopper(II) carbohydrazone complex

An unusual copper(II) complex [Cu(L^1a)₂Cl₂] CH₃OH·H₂O·H₃O⁺Cl⁻ (1a) was isolated from a solution of a novel tricopper(II) complex [Cu₃(HL¹)Cl₂]Cl₃·2H₂O (1) in methanol, where L^1a is 3-(2-pyridyl)triazolo[1,5-a]-pyridine, and characterized with single crystal X-ray diffraction study. The tricopper(II) complex of potential ligand 1,5-bis(di-2-pyridyl ketone) carbohydrazone (H₂L¹) was synthesized and physico-chemically characterized, while the formation of the complex 1a was followed by time-dependant monitoring of the UV–visible spectra, which reveals degradation of ligand backbone as intensity loss of bands corresponding to O → Cu(II) charge transfer.