Formation Of Mono Research Articles

Selectivity of lipases for estolides synthesis

Abstract Lipase-catalyzed synthesis of estolides starting from different saturated (C16 16OH, C18 12OH) and unsaturated (C18:1 9 cis 12-OH) hydroxy-fatty acids was investigated. For this reason, the catalytic efficiency of several native and immobilized lipases in different organic reaction media at temperatures up to 75 °C was studied. The formation of mono- and di-lactone as well as estolide’s chain elongation depends on the type and source of lipase. The lipase from Pseudomonas stutzeri immobilized by cross-linking as cross-linked enzymes aggregates (CLEAs) was the best biocatalyst in terms of chain elongation. Estolides with polymerization degree up to 10 were obtained at substrate conversions higher than 80 %.

Cobalt Phenanthroline–Indole Macrocycles as Highly Active Electrocatalysts for Oxygen Reduction

The replacement of scarce and expensive platinum species poses a challenge in fuel-cell development. The design and synthesis of a novel type of Co(II) -N4 macrocyclic complex, [CoN4 ], based on the phenanthroline-indole macrocyclic ligand (PIM) is reported. This unique ligand allows the formation of mono- and dinuclear complexes with defined active sites that facilitate the direct four-electron reduction of oxygen. Electrochemical measurements revealed that the [CoN4 ]/C (20 wt %) catalysts have a high activity and long-term stability for the oxygen-reduction reaction (ORR) under alkaline conditions, similar to the Pt/C catalyst. These structurally well-defined complexes represent a nonprecious alternative to platinum species for future fuel-cell applications.

Synthesis and α‐Glucosidase and α‐Amylase Inhibitory Activity Evaluation of Azido‐ and Aminocyclitols

AbstractFor the synthesis of some azido‐ and aminocyclitols, (3aRS,7aSR)‐1,3,3a,7a‐tetrahydroisobenzofuran was used as the starting material. For further functionalization of the diene unit, the diene was subjected to epoxidation reactions to give mono‐ and bisepoxides depending on the amount of m‐chloroperbenzoic acid used. The ring‐opening of the epoxide functionality with NaN3 resulted in the formation of mono‐ and bisazido cyclitols. The tetrahydrofuran ring was opened in an acid‐catalysed reaction with sulfamic acid. The reduction of azide groups to give amines provided various amino‐ and bisaminocyclitol derivatives. The inhibitory effects of 20 compounds against α‐glucosidase and α‐amylase were tested. The results indicated that some of these compounds seem to have good inhibitory activity against α‐glucosidase, and low inhibitory activity against α‐amylase. Furthermore, it was demonstrated that the number and position of azides, amines, and hydroxy groups appeared to play an important role in determining the inhibitory potency of these compounds.

A multiprotic indole-based thiocarbohydrazone in the formation of mono-, di- and hexa-nuclear metal complexes

A new thiocarbohydrazone (LH4) derived from indole-7-carbaldehyde was synthesized and reacted with NiII, PdII, PtII, CuI and AgI salts to bind the metals in various coordination fashions, forming complexes with different nuclearities. The reaction with CuCl in the presence of PPh3 produced a dinuclear CuI complex with the formula [Cu2Cl2(LH4)2(PPh3)2], in which LH4 binds the metals as a neutral μ2-S-donor ligand. The reaction of the thiosemicarbazone with AgI resulted in the formation of a hexanuclear complex featuring an Ag6S6 core. The ligand in this complex is monoanionic and uses the sulfur and a hydrazinic nitrogen atom in binding to the metals. The reaction of LH4 with [MCl2(PPh3)2] (M=NiII, PdII and PtII) at room temperature yielded complexes of the type [M(LH2)(PPh3)]. The thiocarbohydrazone in these complexes takes advantage of one indole N atom donor to act as a dianionic NNS tridentate ligand. A modification of the conditions of the reaction with the PdII salt led to the formation of the dinuclear complex [Pd2Cl(LH)(PPh3)3]. In this molecule, the thiocarbohydrazone is triply deprotonated and chelates one metal center by its dianionic NNS pocket, while coordinating the second metal ion through a hydrazinic N atom. The structure of the molecules was studied by X-ray crystallography and NMR spectroscopy.

Dependence of the enthalpies of formation of glycylglycinate complexes of nickel(II) on the composition of a mixed water-dimethylsulfoxide solvent

The heat effects of the complexation reactions of nickel(II) with a glycylglycinate ion in a water-dimethylsulfoxide solvent in a range of compositions of 0.00–0.60 molar parts of dimethylsulfoxide (DMSO) (an ionic strength of 0.1 was maintained using sodium perchlorate) were determined by means of calorimetry at 298.15 K. It is established that the exothermicity of complexation reactions rises by the first two steps and falls upon the addition of a third glycylglycinate anion with an increase in the concentration of DMSO. It is shown that the formation of mono- and bis-glycylglycinate complexes of nickel(II) in a water-DMSO solvent is determined mostly by the enthalpic contribution. It is concluded that the formation of tris-ligand complexes is more associated with the entropic contribution.

Thermodynamic properties of chloramine formation and related reactions during water treatment: A G4MP2, G4, and W1BD theoretical study

A high-level gas and aqueous phase theoretical thermodynamic study was conducted on the primary and related chemical reactions which occur during chloramination for water treatment using the G4MP2, G4, and W1BD composite methods with the SMD, PCM, and CPCM solvation models. The standard state (298.15 K, 1 atm or 1M) formation of mono-, di-, and tri-chloramines from their precursors via hypochlorous acid chlorination is substantially exothermic and exergonic in both the gas and aqueous phases. The excellent agreement between experimental and theoretical values for a range of structural and thermodynamic calculations on a suite of calibration compounds suggests that the G4MP2, G4, and W1BD calculations meet or exceed criteria for thermochemical accuracy. The temperature influence on the thermodynamics of chloramine formation is projected to be negligible regardless of phase between 0 and 100°C. Additional thermodynamic calculations were undertaken on associated chloramination reactions involving the disproportionation of monochloramine, the decomposition of di- and tri-chloramine, and the reactions of trichloramine with ammonia and dichloramine. The results from these investigations not only provide a better understanding of the reaction thermodynamics, they also allow for a more rigorous interpretation of proposed chloramination mechanisms.

Synthesis of Unsymmetrical Aryl-Ethynylated Benzenes via Regiocontrolled Sonogashira Reaction of 1,3,5-Tribromobenzene

Sonogashira coupling of trimethylsilylacetylene with 4-alkyloxy-1-iodobenzenes gave 2-(4-(alkyloxy)phenyl)ethynyltrimethylsilanes which undergo deprotection via removal of TMS-group using tetrabutylammonium fluoride (TBAF) in THF at room temperature to afford the corresponding terminal 2-(4-(alkyloxy)phenyl)acetylenes. Regiocontrolled Sonogashira cross-coupling of 1,3,5-tribromobenzene with the terminal arylacetylenes in aqueous medium resulted in the formation of mono-, di- and tri-alkynylated benzene derivatives in moderate to good yields. Factors affecting the regioselective alkynylation were also examined.

The role of hydroxo-bridged dinuclear species and the influence of "innocent" buffers in the reactivity of cis-[Co(III)(cyclen)(H₂O)₂]³⁺ and [Co(III)(tren)(H₂O)₂]³⁺ complexes with biologically relevant ligands at physiological pH.

In view of the relevance of the reactivity of inert tetraamine Co(III) complexes having two substitutionally active cis positions capable of interact with biologically relevant ligands, the study of the reaction of cis-[Co(cyclen)(H2O)2](3+) and [Co(tren)(H2O)2](3+) with chlorides, inorganic phosphate and 5'-CMP (5'-cytidinemonophosphate) has been pursued at physiological pH. The results indicate that, in addition to the actuation of the expected labilising conjugate-base mechanism, the formation of mono and inert bis hydroxo-bridged species is relevant for understanding their speciation and reactivity. The reactivity pattern observed also indicates the key role played by the "innocent" buffers frequently used in most in vitro studies, which can make the results unreliable in many cases. The differences between the reactivity of inorganic and biologically relevant phosphates has also been found to be remarkable, with outer-sphere hydrogen bonding interactions being a dominant factor for the process. While for the inorganic phosphate substitution process the formation of μ-η(2)-OPO2O represents the termination of the reactivity monitored, for 5'-CMP only the formation of η(1)-OPO3 species is observed, which evolve with time to the final dead-end bis hydroxo-bridged complexes. The promoted hydrolysis of the 5'-CMP phosphate has not been observed in any of the processes studied.

Alachlor oxidation by the filamentous fungus Paecilomyces marquandii

Alachlor, a popular chloroacetanilide herbicide, can be a potential health risk factor. Soil microorganisms are primarily responsible for conversion and migration of alachlor in natural environment, but knowledge concerning alachlor biodegradation is not complete. Therefore, we studied the ability of Paecilomyces marquandii, soil fungus tolerant to heavy metals, to eliminate alachlor and proposed a new pathway of its transformation. After 7 days of incubation only 3.3% of alachlor was detected from an initial concentration 50mgL−1 and 20.1% from a concentration 100mgL−1. The qualitative IDA LC–MS analysis showed the presence of ten metabolites. All of them were dechlorinated mainly through oxidation, but also reductive dechlorination was observed. The main route of alachlor conversion progressed via N-acetyl oxidation resulting in the formation of mono-, di- and trihydroxylated byproducts. N-acetyl oxidation as a dominant route of alachlor metabolism by fungi has not been described so far. The toxicity of alachlor tested with Artemia franciscana did not increase after treatment with P. marquandii cultures. Paecilomyces marquandii strain seems to be an interesting model for the research on alachlor conversion by soil microscopic fungi, due to its dechlorination and hydroxylation ability as well as high tolerance to heavy metals.

Reactivity of 2-chalcogenopyridines with palladium–phosphine complexes: isolation of different complexes depending on the nature of chalcogen atom and phosphine ligand

Reactions of either Pd(0) phosphine complexes with dipyridyldichalcogenides or [PdCl2(P∩P)] (P∩P = dppe, dppp) with pyridylchalcogenolate ions have been examined and a variety of Pd(II) complexes have been isolated and characterized. Oxidative addition of {SeC5H3(3-R)N}2 (R = H or Me) to [Pd(P∩P)2] (P∩P = dppe, dppp) gave either a mononuclear complex, [Pd{2-Se-C5H3(3-R)N}2(P∩P)] (for P∩P/R: dppe/H or Me; dppp/H) or a cationic binuclear complex, [Pd2{μ-SeC5H3(3-Me)N}2(dppp)2]2+ (4b) (R = Me) whereas reactions involving the tellurium analogue exclusively afforded trinuclear complexes, [Pd3(μ-Te)2(P∩P)3]Cl2 (P∩P = dppe (2) or dppp (6)). The latter was also obtained in the substitution reaction between [PdCl2(P∩P)] and NaTeC5H3(3-R)N. The substitution reactions between [PdCl2(dppe)] and Pb{EC5H3(3-R)N}2 yielded mononuclear complexes, [Pd{2-E-C5H3(3-R)N}2(dppe)] (1a–1e) (E = S, Se or Te) while in the case of [PdCl2(dppp)], the reactions resulted in the formation of mono-, bi- and tri- nuclear complexes depending on the nature of the chalcogen atom (E = S, Se or Te) and the substituent on the pyridyl ring (R = H or Me). Treatment of dipyridyl ditellurides, {TeC5H3(3-R)N}2 (R = H or Me), with [Pd(PPh3)4] gave expected tellurolate complexes, [Pd{2-TeC5H3(3-R)N}2(PPh3)2] (7a, 7b) which on prolonged standing in CDCl3 solution gave green crystals of [PdCl{2-Te(Cl)2C5H3(3-Me)N}(PPh3)] (9). The molecular structures of {TeC5H3(3-Me)N}2, [Pd2{μ-TeC5H3(3-Me)N}2(dppp)2]Cl2·3H2O (5·3H2O), [Pd3(μ-Te)2(dppp)3]Cl2·3CHCl3 (6·3CHCl3) and [PdCl{2-Te(Cl)2C5H3(3-Me)N}(PPh3)] (9) were established by single crystal X-ray diffraction analyses.

Synthesis of Highly Substituted Nitro/Ha­lo-meso-tetraaryl­porphyrins by Tandem Cyclocondensation/Aromatic Electrophilic Nitration Reactions

Synthesis of highly functionalized nitro/halo-5,10,15,20-tetraaryl porphyrins is described. meso-Tetraphenylporphyrin derivatives (halo-substituted in meso-phenyl rings; with F, Cl, Br, and I), in the reaction with fuming yellow nitric acid (d = 1.52), result in the formation of mono-, di-, tri-, and even tetranitro-substituted porphyrins (with summary yields of 28–81%), depending on the reaction temperature (0 °C to 5 °C or at r. t.), amounts of the acid used, and reaction time. In some cases moderate selectivity was observed. The starting halo-substituted meso-tetraarylporphyrins were prepared in the cyclocondensation reaction of pyrrole with the respective aromatic aldehydes (usually carried out according to known procedures). By this route, the preparation of the synthetic porphyrins (bearing up to ten halo-/ nitro-substituents) was demonstrated.

The influence of d-mannitol on the effectiveness of boric acid transport during electrodialytic desalination of aqueous solutions

Previous studies have shown that electrodialytic (ED) desalination can be effective in separating boric acid from salts, and a model for the transport of boric acid during ED desalination has been proposed.In this study, the influence of d-mannitol on the effectiveness of boric acid transport during ED desalination of aqueous solutions was investigated. The experimental results of periodic desalination were compared with results predicted from a previously proposed model of boric acid mass transport. Both the concentrate and the electrode rinse solution contained lower than predicted amounts of boric acid, especially at high diluate boric acid concentration. This difference was shown to be due to the reaction between monoborate and d-mannitol, which resulted in the formation of mono- and dichelate complexes and therefore significantly reduced the equilibrium concentration of boric acid in the diluate. This phenomenon was observed despite the low pH of the diluate. The equilibrium concentration of boric acid in the diluate was calculated using the model for chemical equilibrium. The results were then analyzed with the model for boric acid transport. A good agreement between the predicted and the measurements results was found. The combined model was therefore shown to be accurate in predicting the effectiveness of boric acid transport during ED desalination of mixtures of boric acid and d-mannitol. The effect of d-mannitol was such that it reduced the equilibrium concentration of boric acid in the diluate. This, in turn, reduced the boric acid flux across the membrane. The extent of the above reduction in boron flux can be predicted based on the combined model provided in this work. No evidence of borate complexes and d-mannitol transport across IEMs was observed.

Spectral, Electrochemical, Fluorescence, Kinetic and Anti-microbial Studies of Acyclic Schiff-base Gadolinium(III) Complexes

Centre for Advanced Studies in Botany, University of Madras, Guindy Maraimalai Campus, Chennai 600 025, IndiaReceived June 5, 2012, Accepted August 1, 2012A new series of acyclic mononuclear gadolinium(III) complexes have been prepared by Schiff-base con-densation derived from 5-methylsalicylaldehyde, diethylenetriamine, tris(2-aminoethyl) amine, triethylene-tetramine, N,N-bis(3-aminopropyl)ethylene diamine, N,N-bis(aminopropyl) piperazine, and gadolinium nitrate.All the complexes were characterized by elemental and spectral analyses. Electronic spectra of the complexesshow azomethine (CH=N) within the range of 410-420 nm. The fluorescence efficiency of Gd(III) ion in thecavity was completely quenched by the higher chain length ligands. Electrochemical studies of the complexesshow irreversible one electron reduction process around −2.15 to −1.60 V The reduction potential ofgadolinium(III) complexes shifts towards anodic directions respectively upon increasing the chain length. Thecatalytic activity of the gadolinium(III) complexes on the hydrolysis of 4-nitrophenylphosphate was determin-ed. All gadolinium(III) complexes were screened for antibacterial activity. Key Words : Schiff-base ligands, Gadolinium(III) complexes, Fluorescence, Kinetic, Anti-microbialIntroductionIn the past decade, a great attention has been devoted tothe design and the synthesis of macrocyclic ligands and theirlanthanide complexes are a fascinating area of research,owing to their importance in basic and applied chemistry. Inparticular, acyclic Schiff bases have successfully been pro-posed as excellent systems in the formation of mono, homo,hetero nuclear lanthanide complexes.

N-Acetylation of p-Aminobenzoic Acid and p-Phenylenediamine in Primary Porcine Urinary Bladder Epithelial Cells and in the Human Urothelial Cell Line 5637

N-Acetyltransferases (NAT) are important enzymes in the metabolism of certain carcinogenic arylamines, as N-acetylation decreases or prevents their bioactivation via N-hydroxylation. To study such processes in the bladder, cell culture models may be used, but metabolic competence needs to be characterized. This study focused on the N-acetylation capacity of two urothelial cell systems, using p-aminobenzoic acid (PABA) and the hair dye precursor p-phenylenediamine (PPD), two well-known substrates of the enzyme NAT1. The constitutive NAT1 activity was investigated using primary cultures of porcine urinary bladder epithelial cells (PUBEC) and in the human urothelial cell line 5637 to assess their suitability for further in vitro studies on PABA and PPD-induced toxicity. N-Acetylation of PABA and PPD was determined by high-performance liquid chromatography (HPLC) analysis in cytosols of the two cell systems upon incubation with various substrate levels for up to 60 min. The primary PUBEC revealed higher N-acetylation rates (2.5-fold for PABA, 5-fold for PPD) compared to the 5637 cell line, based on both PABA conversion to its acetylated metabolite and formation of mono- and diacetylated PPD. The urothelial cell systems may thus be useful as a tool for further studies on the N-acetylation of aromatic amines via NAT1.

Mild and High‐Yielding Molybdenum(VI) Dichloride Dioxide‐Catalyzed Formation of Mono‐, Di‐, Tri‐, and Tetracarbamates from Alcohols and Aromatic or Aliphatic Isocyanates

AbstractBoth molybdenum(VI) dichloride dioxide (MoO2Cl2) and its dimethylformamide (DMF) complex catalyze the addition of alcohols to isocyanates giving carbamates. Most additions proceeded to completion at room temperature within 20 min using as little as 0.1 mol% of the catalyst when working on a 1‐mmol scale or just 100 ppm working on a 20‐mmol scale. Sterically encumbered substrates reacted to completion when 1 mol% of the catalyst was employed. Diols, triols, and tetraols reacted with monoisocyanates likewise, as did monofunctional alcohols and diisocyanates. These pairings furnished di‐, tri‐, tetra‐, and dicarbamates, respectively. Reactants, which were poorly soluble in CH2Cl2 at room temperature required elevating the temperature and possibly choosing a higher‐boiling solvent (ClCH2CH2Cl, DMF) as well. Additions of diols to diisocyanates were feasible, too, giving polycarbamates as we presume.

Improved Solvent Formulations for Efficient CO2 Absorption and Low‐Temperature Desorption

This experimental study describes efficient CO₂ capture by 2-amino-2-methyl-1-propanol (AMP)/piperazine (PZ) in ethylene glycol monoethyl ether (EGMEE, 2-ethoxyethanol) containing approximately 15 wt % of water. In these experiments, the solvent is continuously circulated between the absorber (packed-bed reactor at 30, 40, or 45 °C) and the desorber (at 80, 85, or 90 °C). The CO₂ -solvent reaction equilibria have been investigated by using ¹³C NMR spectroscopy, which provides confirmatory evidence that the formation of mono- and biscarbamate derivatives of PZ accounts for most of the CO₂ absorbed by the AMP/PZ/EGMEE/H₂O blend. The solid-state structures of AMP carbamate and of the carbonate salt of protonated AMP have been determined by using XRD. Both AMPCO₂(-) and CO(3)(2-) species completely convert to the monoalkyl carbonates on dissolving the respective salts in methanol, ethanol, or ethylene glycol.

Reaction of 1,3,5-tri-tert-butylbenzene with 2,4,6,8-tetraiodo-2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-dione

Reactions of 1,3,5-tri-tert-butylbenzene with 2,4,6,8-tetraiodo-2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-dione in acetic and trifluoroacetic acids involve substitution of one or two tert-butyl groups in the aromatic ring with formation of mono-, di-, and triiodo-substituted derivatives. No iodo derivatives are formed in acetonitrile.

Macroscopic and Molecular Insights from CO Adsorption on NaY Zeolite: A Combined FTIR and Manometric Study

This survey combines both quantitative and IR molecular descriptions and aims to provide new insights for the description of CO adsorption on NaY zeolite at 77 K. Quantitative measurements of the number of CO molecules trapped in the microporous super cage are compared to the corresponding IR spectra of CO as adsorbed species. We demonstrate that polycarbonyls formed during the completion of the accessible SII Na+ coordinative vacancies result in the formation of mono-, di- and tricarbonyls but not consecutively. Quantitative analysis and measurements of the CO molecules that are adsorbed prove that polycarbonyls coexist with different proportions over the adsorption step in line with previous theoretical prediction.(1) Moreover, we establish that polycarbonyl formation settles rapidly and stops, although the completion of the SII Na+ coordinative vacancies has not been fully achieved. The formation of CO in the pseudoliquid phase causes this adsorption limitation, and distinction within adsorbed species must be made between species that are truly Na+-coordinated and those that are adsorbed in a condensed state in the confined micropores. As a result, this combined analysis reveals that the sole manometric measurements resulting in the macroscopic CO isotherm overestimate the number of “true” coordinated species.

Low-temperature activation of nitrogen oxide on Cu-ZSM-5 catalysts

The adsorption and activation of NO molecules on Cu-ZSM-5 catalysts with different Cu/Al and Si/Al ratios (from 0.05 to 1.4 and from 17 to 45, respectively) subjected to different pretreatment was studied by ultraviolet-visible diffuse reflectance (UV-Vis DR). It was found that the amount of chemisorbed NO and the catalyst activity in NO decomposition increased with an increase in the Cu/Al ratio to 0.35–0.40. The intensity of absorption bands at 18400 and 25600 cm−1 in the UV-Vis DR spectra increased symbatically. It was hypothesized that the adsorption of NO occurs at Cu+ ions localized in chain copper oxide structures with the formation of mono- and dinitrosyl Cu(I) complexes, and this process is accompanied by the Cu2+...Cu+ intervalence transfer band in the region of 18400 cm−1. The low-temperature activation of NO occurs through the conversion of the dinitrosyl Cu(I) complex into the π-radical anion (N2O2)− stabilized at the Cu2+ ion of the chain structure, [Cu2+-cis-(N2O2)−], by electron transfer from the Cu+ ion to the cis dimer (NO)2. This complex corresponds to the L → M charge transfer band in the region of 25600 cm−1. The subsequent destruction of the complex [Cu2+-cis-(N2O2)−] at temperatures of 150–300°C leads to the release of N2O and the formation of the complex [Cu2+O−], which further participates in the formation of the nitrite-nitrate complexes [Cu2+(NO2)−], [Cu2+(NO)(NO2)−], and [Cu2+(NO3)−] and NO decomposition products.

Study of half-sandwich mono and dinuclear complexes of platinum group metals containing pyrazolyl pyridine analogues: Synthesis and spectral characterization

The chelating ligands 3-chloro-6-(3-pyridyl-1-pyrazolyl)pyridazine (pp-Cl) and 3,6-bis(3-pyridyl- 1-pyrazolyl)pyridazine (bppp), were prepared by the condensation of pyridylpyrazole and 3,6-dichloropyridazine. The mononuclear complexes [(η 6-arene)Ru(pp-Cl)Cl] + {η 6-arene = C6H6 (1); p-iPrC6H4Me (2)}, [(η 5-C5Me5)M(pp-Cl)] + {M = Rh (3); Ir (4)}, [(η 6-arene)Ru(bppp)Cl] + {η 6-arene = C6H6 (5); p-iPrC6H4Me (6)}, [(η 5-C5Me5)M(bppp)] + {M =Rh (7); Ir (8)} as well as the binuclear complexes [{(η 6-arene)RuCl}2(bppp)]2 + {η 6 -arene =C6H6 (9); p-iPrC6H4Me (10)} and [{(η 5-C5Me5)MCl}2(bppp)]2 + {M = Rh (11); Ir (12)} have been synthesized from 3-chloro-6-(3-pyridyl-1-pyrazolyl)pyridazine (pp-Cl) or 3,6-bis(3-pyridyl-1-pyrazolyl)pyridazine (bppp) and the corresponding dimers [(η 6-arene)Ru(μ-Cl)Cl]2 and [Cp*M(μ-Cl)Cl]2, respectively. All complexes were isolated as their hexafluorophosphate salts and characterized by IR, NMR, mass spectrometry and UV-visible spectroscopy. The molecular structures of [2]PF6 and [7]PF6 have been established by single crystal X-ray structure analysis. The chelating ligands, 3-chloro-6-(3-pyridyl-1-pyrazolyl)pyridazine (pp-Cl) and 3,6-bis(3-pyridyl-1-pyrazolyl)pyridazine (bppp), were synthesized and their reactions with arene ruthenium, Cp* rhodium and Cp* iridium dimers resulted in the formation of mono and dinuclear complexes. The complexes were characterized by spectral techniques; the structures of representative compounds were confirmed by single crystal X-ray studies.