2-pyridyl Ketone Research Articles

Triangular Ni(II) complexes from the use of 2-pyridyl oximes

The reactions of representative 2-pyridyl oximes with Ni II salts in the presence of a base have been investigated. The synthetic study has led to the new triangular complexes [Νi 3(ppko) 6]·2H 2O·0.5EtOH·MeOH ( 1·2H 2O·0.5EtOH·MeOH), [Νi 3(mpko) 3(HCO 2) 2(mpkoH) 2](ClO 4) ( 2) and [Νi 3(ppko) 3(HCO 2) 2(ppkoH) 2](ClO 4) ( 3), where ppko − is the anion of phenyl(2-pyridyl)ketone oxime and mpko − is the anion of methyl(2-pyridyl)ketone oxime. The structures of compounds 1 and 2 have been determined by single crystal X-ray diffraction. The ppko − ligand in 1 adopts four different coordination modes including the unique N pyridylO oximate chelating one which gives rise to a 6-membered chelating ring, while the neutral and the deprotonated oxime ligands in 2 adopt three different coordination modes. The magnetic properties of 1 and 2 have been studied by variable-temperature dc magnetic susceptibility techniques which indicate antiferromagnetic interactions.

Strong antiferromagnetic coupling in doubly N, O oximato-bridged dinuclear copper(II) complexes

The use of di-2-pyridyl ketone oxime, (py)pkoH, and phenyl 2-pyridyl ketone oxime, ppkoH, in copper(II) hexafluoroacetylacetonate chemistry is reported. The reaction of CuCl 2·2H 2O with one and two equivalents of ppkoH and Na(hfac), respectively, in CH 2Cl 2 affords the dinuclear complex [Cu 2(hfac) 2(ppko) 2] ( 1) in excellent yield. The replacement of ppkoH by (py)pkoH gives the isostructural compound [Cu 2(hfac) 2{(py)pko} 2] ( 2) in good yield. The Cu II atoms in both 1 and 2 are doubly bridged by the oximate groups of two η 1:η 1:η 1:μ 2 ppko − and (py)pko − ligands, respectively. The bridging Cu–(R–NO)–Cu′ units are not planar, with the torsion angles being 23.2° ( 1) and 20.3° ( 2). A bidentate chelating hfac − ligand completes five-coordination at each square pyramidal metal ion. The hfac −-free reaction system CuCl 2·2H 2O/(py)pkoH/NEt 3 (1:2:1) gives instead the mononuclear complex [CuCl{(py)pko}{(py)pkoH}] ( 3) in very good yield. The Cu II atom is coordinated by two N, N′-bidentate (py)pko −/(py)pkoH chelates and a monodentate chloride anion resulting in a distorted square pyramidal geometry around the metal center. Variable-temperature, solid-state dc magnetic studies were carried out on the representative dinuclear complex 1 in the 2.0–300 K range. The data indicate a very strong antiferromagnetic exchange interaction and a resulting S = 0 ground state, which is well isolated from the S = 1 excited state. The J value of −720 cm −1 was derived from the fitting of the experimental data using the Hamiltonian H = − J( S 1 · S 2).

2-Pyridyl ketone oximes in iron(III) carboxylate chemistry: Synthesis, structural and physical studies of tetranuclear clusters containing the [Fe 4( μ3-O) 2] 8+ ‘butterfly’ core

The use of 2-pyridyl ketone oximes, pyC(R)NOH (R = H, Me), in iron(III) carboxylate chemistry yielded the tetranuclear complexes [Fe 4O 2Cl 2(O 2CPh) 2{pyC(R)NO} 4] (R = H, 1; R = Me, 2). The crystal structure of 2 revealed the presence of a central [Fe 4( μ 3-O) 2] 8+ core comprising four Fe III ions in a ‘butterfly’ disposition and two μ 3-O 2− ions, each bridging three Fe III ions forming the ‘wings’ of the ‘butterfly’. The Mössbauer spectra from polycrystalline samples of 2 consist of composite quadrupole-split doublets, with parameters typical for high-spin iron(III) in octahedral environments. Magnetic susceptibility measurements on 2 revealed antiferromagnetic interactions between the S = 5/2 ferric ions; fits to the data required the use of two different parameters for the wingtip–body interactions. The best-fit values for these interactions were J 1 = −85 cm −1 and J 2 = −27 cm −1 (-2 J ijS iS j Hamiltonian formalism) resulting to a diamagnetic ground state.

Employment of the sulfate ligand in 3d-metal cluster chemistry: A novel hexanuclear nickel(II) complex with a chair metal topology

The preparation and crystal structure of a hexanuclear Ni(II) sulfato cluster containing the anion of phenyl(2-pyridyl)ketone oxime, (py)C(ph)NO −, is reported. Treatment of NiSO 4·6H 2O with 1 equiv. of (py)C(ph)NOH and 1 equiv. of NaOMe in DMF under reflux leads to the compound [Νi 6(SO 4) 2{(py)C(ph)NO} 8] ·6DMF ( 1·6DMF) in moderate yield. The metal ions are linked together by two 3.211 (Harris notation) (py)C(ph)NO − ligands, six 2.111 (py)C(ph)NO − ligands and two 5.2210 SO 4 2 - ions. Its skeleton consists of six Ni II ions arranged in a chair conformation. Compound 1 joins a small family of structurally characterized metal complexes containing the neutral or anionic forms of phenyl(2-pyridyl)ketone oxime as ligands, and it is a rare example in which the SO 4 2 - ions are coordinated in the 5.2210 fashion. Characteristic IR bands are discussed in terms of the known structure of 1. Its magnetic properties have been studied by variable-temperature dc magnetic susceptibility techniques which indicate competitive antiferromagnetic interactions within its triangular subunits.

Selective Ethylene Oligomerization with Nickel Oxime Complexes

Two nickel-oxime complexes, Ni (2-pyridine aldoxime)2 dichloride (6) and Ni (methyl 2-pyridyl ketone oxime)2 dichloride (7), were prepared and characterized by X-ray crystallography. Both complexes are six-coordinate and have 2-pyridylimines as ligand backbones, where the two nitrogen atoms from each of the oxime ligands coordinate to the metal, but the oxygen atom remains protonated and does not participate in bonding to the metal center. The complexes were found to be selective ethylene dimerization catalysts in the presence of cocatalyst such as methylaluminoxane (MAO) or diethyl aluminum chloride (DEAC). With DEAC, the productivity is considerably higher than with MAO. Under optimum conditions the productivity values are as high as 200 kg/mol catalyst/h/bar (for 6) to 335 kg/mol catalyst/h/bar (for 7). The selectivities toward dimerization under these conditions are 84% and 77%, respectively, with the terminal isomer 1-butene being the only (≥99.5%) C4 product.

Synthesis of alkyl nitrones by reaction of aldehyde and ketone oximes with α,β-unstaturated esters in the presence of Lewis acid

Reactions of pyridinecarbaldehyde oximes, methyl pyridyl ketone oximes, furfural oxime, cinnamaldehyde oxime, and crotonaldehyde oxime with acrylic and methacrylic acid esters in the presence of a Lewis acid catalyst at room temperature followed the conjugate addition pattern to give the corresponding alkyl nitrones in good yield. The best yields were obtained using a 1: 1 mixture of CdI2 and BF3 · Bu2O as catalyst.

Density Functional Theory and Time-Resolved Resonance Raman Investigation of the Photocyclization of 2-Pyridyl Phenyl Ketone in Acid Solution

Density functional theory computations and nanosecond time-resolved resonance Raman (ns-TR(3)) spectroscopy experiments were done to study the photocyclization of 2-pyridyl phenyl ketone in acid solution. The most probable cyclization pathway was assigned to the reaction RX1, which had the lowest free-energy barrier. The factors that determine the free-energy barriers among the different reactions examined were discussed. Solvent effects on these reactions were also explored by calculations that included a polarizable continuum model for the bulk solvent effect.

Dichloridobis(phenyl 2-pyridyl ketone oxime)nickel(II) acetone solvate

The Ni atom in the title compound, [NiCl2(C12H10N2O)2]·C3H6O, adopts a distorted octa­hedral geometry, being ligated by four N atoms from two different phenyl 2-pyridyl ketone oxime ligands and two Cl atoms. In the crystal structure, inter­molecular O—H⋯Cl hydrogen bonds link the mol­ecules into a chain structure along [010]. There is a π–π contact between the pyridine rings [centroid–centroid distance = 3.824 (5) Å].

Employment of methyl 2-pyridyl ketone oxime in manganese non-carboxylate chemistry: MnII2MnIV and MnII2MnIII6 complexes

The employment of the anion of methyl 2-pyridyl ketone oxime (mpko(-)) as a tridentate chelating/bridging ligand in manganese chemistry is described. The inorganic anion (Br(-), ClO(4)(-)) used in the reaction affects the identity of the product. The reaction of MnBr(2) and one equivalent of mpkoH in the presence of a base affords [Mn(3)(OMe)(2)(mpko)(4)Br(2)] (3), which is mixed-valence (2Mn(II), Mn(IV)). The central Mn(IV) atom in each of the two, crystallographically independent, centrosymmetric molecules is coordinated by four oximate oxygen atoms belonging to the eta(1):eta(1):eta(1):mu mpko(-) ligands, and two eta(1):mu MeO(-) groups, while six coordination at each terminal Mn(II) atom is completed by four nitrogen atoms belonging to the 'chelating' part of two mpko(-) ligands, and one Br(-) ion. The Mn(II) atoms have trigonal prismatic coordination geometry. The reaction of Mn(ClO(4))(2).6H(2)O, mpkoH and OH(-) (1:2:1) in MeOH gives [Mn(8)O(4)(OMe)(mpko)(9)(mpkoH)](ClO(4))(4) (4), which is also mixed-valence (2Mn(II), 6Mn(III)) and possesses the novel [Mn(8)(mu(3)-O)(4)(mu-OMe)(mu-OR'')(2)](11+) core. The latter possesses a U-shaped sequence of four fused {Mn(II)Mn(III)(2)(mu(3)-O)}(6+) triangular units, with a Mn(III)-Mn(III) edge being shared between the central triangles. Variable-temperature, solid-state dc and ac magnetic susceptibility studies were carried out on complexes 3 and 4 . The dc susceptibility data for 3 in the 5.0-300 K range have been fit to a model with two J values, revealing weak ferromagnetic Mn(II)Mn(IV) (J = +3.4 cm(-1)) and Mn(II)Mn(II) (J' = +0.3 cm(-1)) exchange interactions. Fitting of the magnetization vs. H/T data by matrix diagonalization and including only axial anisotropy (ZFS, D) gave ground state spin (S) and D values of S = 13/2, D = +0.17 cm(-1) for and S = 3, D = -0.09 cm(-1) for 4 . The combined work demonstrates the usefulness of mpko(-) in the preparation of interesting Mn clusters, without requiring the co-presence of carboxylate ligands.

Removal of Copper(II) from Chloride Solutions using Hydrophobic Pyridyl Ketone Oximes

: The model oximes of 1‐(2‐pyridyl)undecane‐1‐one (2PC10), 1‐(2‐pyridyl)tridecane‐1‐one (2PC12) and 1‐(4‐pyridyl)tridecane‐1‐one (4PC12) were synthesized and used for copper(II) extraction from chloride solutions. The behavior of these ligands towards copper(II) extraction was investigated for different experimental conditions with a particular emphasis on the influence of the concentrations of copper ions, chloride ions, and ligand. The obtained results indicated the ability of pyridylketoximes to extract copper(II) from chloride solutions. 2‐Pyridyl ketone oximes are stronger extractants of copper than 4‐pyridyl ketone oximes. Copper can be effectively stripped by water or diluted sulfuric acid.

A family of mononuclear Co III/2-pyridyloximate complexes and their conversion to trinuclear, mixed-valence linear [formula omitted] clusters

The use of the 2-pyridyl oxime ligands (LH) 2-pyridinealdoxime, methyl 2-pyridyl ketone oxime and phenyl 2-pyridyl ketone oxime in Co chemistry has been investigated and led to two families of compounds. The first family includes the mononuclear octahedral, low-spin complexes [Co III(L) 3], while the second family consists of the trinuclear, mixed-valent linear clusters [ Co III 2 Co II(L) 6]X 2 (X = ClO 4 - , PF 6 - ). The latter are prepared by the reactions of the former with an appropriate Co II source. The structural, physical and spectroscopic properties of the complexes are described.

Synthesis, crystal structure and properties of three different derivatives of bis[di(2-pyridyl)methanediol]copper(II), [Cu(bpmd)2]2+¶

In an attempt to obtain ternary copper(II) [Cu(II)] complexes where bis(2-pyridyl) ketone (bpk) could induce the fac-O2 + N(apical) conformation in the HL2− form of two different nitrilotriacetates (HNTA2− and HDNTA2−), we obtained [Cu(bpmd)2][Cu(HNTA)2] · 2H2O (1) and [Cu(bpmd)2](H2DNTA)2 · 4H2O (2) where bpmd is di(2-pyridyl)methanediol. On this basis, the salt [Cu(bpmd)2][Cu(IDA)2] · 6H2O (3) [iminodiacetate (IDA) ligand] was also obtained. The crystallographic studies of these compounds revealed that the common cation of these salts results from aquation of bpk in the aqueous media. The aquation of bpk is unexpectedly fast in the case of 1 because crystals appeared on the same day of the synthesis. ¶This article is dedicated to Professor Alfredo Mederos for his contribution to the coordination chemistry.

Investigation of the MSO 4 · xH 2O (M = Zn, x = 7; M = Cd, x = 8/3)/methyl 2-pyridyl ketone oxime reaction system: A novel Cd(II) coordination polymer versus mononuclear and dinuclear Zn(II) complexes

The reactions of methyl 2-pyridyl ketone oxime, (py)C(Me)NOH, with MSO 4 · xH 2O (M = Zn, x = 7; M = Cd, x = 8/3), in the absence of an external base, have been investigated. The synthetic study has led to the two new complexes [Zn(SO 4){(py)C(Me)NOH}(H 2O) 3] · H 2O ( 1 · H 2O) and [Zn 2(SO 4) 2{(py)C(Me)NOH} 4] · (py)C(Me)NOH [ 2 · (py)C(Me)NOH], and the coordination polymer [Cd(SO 4){(py)C(Me)NOH}(H 2O)] n · [Cd(SO 4){(py)C(Me)NOH}(H 2O) 2] n ( 3). In the three complexes the organic ligand chelates through its nitrogen atoms. The sulfate anion in 1 · H 2O is monodentate; the complex molecule is the mer isomer considering the positions of the aqua ligands. The Zn II centers in 2 · (py)C(Me)NOH are bridged by two syn, anti η 1:η 1:μ 2 SO 4 2 - ligands; each metal ion has the cis– cis– trans disposition of the coordinated sulfate oxygen, pyridyl nitrogen and oxime nitrogens, respectively. The molecular structure of 3 is unique consisting of two different linear and ladder – type chains. π–π stacking interactions and/or hydrogen bonds lead to the formation of interesting supramolecular architectures in the three complexes. The thermal decomposition of complex 3 has been studied. Characteristic vibrational (IR, Raman) bands are discussed in terms of the nature of bonding and the structures of the three complexes.

A new Mn II4Mn III4 cluster from the use of methyl 2-pyridyl ketone oxime in manganese carboxylate chemistry: Synthetic, structural and magnetic studies

The use of methyl 2-pyridyl ketone oxime (mpkoH) in manganese benzoate chemistry is reported. The reaction of Mn(O 2CPh) 2 · 2H 2O with two equivalents of mpkoH in CH 2Cl 2 affords the mononuclear complex [Mn II(O 2CPh) 2(mpkoH) 2] ( 2) in high yield. The Mn II atom is coordinated by two monodentate PhCO 2 - groups and two N, N′-bidentate mpkoH chelates in a cis– cis– trans fashion. Reaction mixtures comprising (NBu n 4)[Mn III 4O 2(O 2CPh) 9(H 2O)] and mpkoH in CH 2Cl 2, [Mn IIMn III 2O(O 2CPh) 6(py) 2(H 2O)] and mpkoH in CH 2Cl 2, or Mn(O 2CPh) 2 · 2H 2O, NBu n 4 MnO 4 and mpkoH in MeOH/MeCN/CH 2Cl 2 all lead to the mixed-valent cluster [Mn II 4Mn III 4O 2(OH) 2(O 2CPh) 10(mpko) 4] ( 3) in moderate yields. The cluster molecule has the [Mn 8(μ 4-O) 2(μ 3-OH) 2] 14+ core (another description of the core is [Mn 8(μ 4-O) 2(μ 3-OH) 2(μ-OR′′) 4(μ-ONR‴) 4] 6+). Peripheral ligation is provided by two η 1, four η 1:η 1:μ and four η 1:η 2:μ 3 PhCO 2 - groups, as well as four η 1:η 1:η 1:μ mpko − ligands. Variable-temperature, solid-state dc and ac magnetic studies were carried out on complex 3 in the 5.0–300 K (dc) and 1.8–10 K (ac) ranges. The data reveal dominant antiferromagnetic interactions and a resulting S = 0 ground state, which is rationalized in terms of the strong antiferromagnetic coupling within the central { Mn 2 III O 2 } 2 + subunit.

A Coumarin‐Based Chromogenic Sensor for Transition‐Metal Ions Showing Ion‐Dependent Bathochromic Shift

AbstractCoumarin pyridyl ketone 1 was designed and synthesized as a new chromogenic sensor for transition‐metal ions. Remarkably, the chemosensor showed ion discrimination by exhibiting different extents of bathochromic shifts: 118 nm for Cu2+, 80 nm for Ni2+, and 55 nm for Cd2+. This ion‐dependent redshift in the visible region allows the selective detection of these three transition‐metal ions by the naked eye. Studies of reference compounds and IR and NMR spectroscopy revealed that the pyridyl ketone moiety was the metal‐binding site, whereas the carbonyl group on the coumarin moiety did not participate in the metal‐binding process.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

4-Pyridyl Carbonyl Compounds as Thrips Lures: Effectiveness for Western Flower Thrips in Y-Tube Bioassays

In a search for chemical lures to manage the cosmopolitan crop pest western flower thrips (WFT), Frankliniella occidentalis, a Y-tube olfactometer was used to screen 20 compounds, including 18 4-pyridyl compounds. Comparison of Y-tube results for New Zealand flower thrips (NZFT), Thrips obscuratus, with field trapping data for ethyl nicotinate and ethyl isonicotinate, suggested that the minimum attractive dose (MAD) of an odor compound, where significantly ( p < 0.05) more than 50% of thrips walked up the odor-laden arm, provided a measure for selecting compounds to evaluate for potential lure efficacy in the field. Eighteen synthetic 4-pyridyl compounds were tested on female WFT in a Y-tube olfactometer and four 4-pyridyl carbonyl compounds had MADs lower than the known WFT attractants p-anisaldehyde (MAD 10 (-3) microL) and ethyl nicotinate (10 (-2) microL): methyl isonicotinate (10 (-6) microL), ethyl-2-chloropyridine-4-carboxylate (10 (-6) microL), ethyl isonicotinate (10 (-4) microL) and methyl 4-pyridyl ketone (10 (-5) microL). The suitability of MAD for selecting compounds for further evaluation of practical lure efficacy is discussed. Comparisons of activities within homologous series of esters and ketones showed that attractant activity decreased with chain length. 4-Formyl pyridine was an attractant at a dose of 10 (-5) microL, but was repellent at higher doses (10 (-2)-10 degrees microL).

Quantum Mechanical Investigation of the Horner-Wadsworth-Emmons Reaction of Benzyl Pyridyl Ketone

The Horner-Wadsworth-Emmons (HWE) reaction is one of much versatile tools in syntheses of α ,β-unsaturated esters, α ,β-unsaturated ketones, and other conjugated systems. Mechanistically, it is generally accepted that the HWE reaction occurs with the addition of enolate derived from phosphonoacetate to aldehyde or ketone, followed by oxaphonphetane formation, pseudorotation, P-C bond cleavage, and then O-C bond cleavage. Stereochemically, the general phosphonoacetates with alkyl phosphonate substituents give E-olefins, which can be explained as a result of the predominant formation of thermodynamically more stable threo adducts. According to an ab initio calculation performed by Ando, in the transition states of the nucleophilic addition to the carbonyl group of acetaldehyde with the trimethyl phosphonoaceate enolate, a transition state leading to Z-olefin (erythro-TS-1) is more stable than threoTS-1 due to a repulsive interaction between the phosphonate moiety and the methyl substituent of aldehyde in threo-TS-1 (Fig. 1). On the other hand, the transition state for the oxaphosphetane formation favors a transition state leading to E-olefin (threo-TS-2) over erythro-TS-2 due to the steric hindrance between the ester moiety and the alkyl substituent of the carbonyl compound (Fig. 1). Based on the energy difference calculated, Ando concluded that the rate-determining transition state for the HWE reaction is TS-2 and, therefore, the threo-olefin is the product of choice. In our recent attempt to convert benzyl phenyl ketone (1, Table 1) to its corresponding olefinic compound (3 and 4, Table 1), the strong preference for E-olefin (3) was also observed (E:Z > 99:1, Table 1) regardless of the base used. However, to our surprise, benzyl 2-pyridyl ketone (2, Table 1), by the reaction with triethyl phosphonoacetate in the presence of t-BuOK, provided a 1:1 mixture of the corresponding E(5) and Z(6) olefins (Entry 4, Table 1) in fairto-good yields. Interestingly, the increased Z-selectivity was not reproduced by use of NaH or LiHMDS as a base (Entires 5 and 6, Table 1), which indicates that the counter cation of the base plays the key role in determining the stereochemi-

REACTIONS OF DIPYRIDYLKETONE WITH GROUP 8 METAL CARBONYLS IN DIFFERENT MEDIA

Reaction of di-(2-pyridyl)ketone (dpk) with [M3(CO)12], M =Ru or Os in dioxan under reduced pressure gave the tricarbonyl derivative [Ru(CO)3(dpk)] (1) and [Os(CO)3(dpk)] (2). When these reactions were carried out in benzene/ethanol 1:1 (v:v) under reflux and reduced pressure gave the binuclear ruthenium complex [Ru2(CO)4(m-CO)(h3-dpkO,Oeth)2] (3),where h3-dpkO,Oeth is N,O,N-ethoxybis(2-pyridyl)-methanolato and the mononuclear [Os(CO)3(h3-dpkO,Oeth) (4). All complexes were characterized by elemental analysis, infrared, mass and 1H NMR spectroscopy. The spectroscopic measurements indicated that in dioxane as solvent the dpk act as bidentate ligand while in benzene/ethanol solution the dpk act as tridentate ligand. The magnetic measurements revealed that the complexes (3) and (4) are paramagnetic with change in the formal oxidation state of the ruthenium and osmium atoms from zero to +1 via oxidative addition of the OH group to ruthenium or osmium with a proton displacement to give a low-spin d7 electronic configuration The UV–Vis studies of the complexes showed blue shift compared to the ligand confirming complex formation.

ESR, electrochemical and cyclodextrin-inclusion studies of triazolopyridyl pyridyl ketones and dipyridyl ketones derivatives

The electron spin resonance (ESR) spectra of free radicals obtained by electrolytic reduction of triazolopyridyl pyridyl ketones and dipyridyl ketones derivatives were measured in dimethylsulfoxide (DMSO). The hyperfine patterns indicate that the spin density delocalization is dependent of the rings presented in the molecule. The electrochemistry of these compounds was characterized using cyclic voltammetry, in DMSO as solvent. When one carbonyl is present in the molecule one step in the reduction mechanism was observed while two carbonyl are present two steps were detected. The first wave was assigned to the generation of the correspondent free radical species, and the second wave was assigned to the dianion derivatives. The phase–solubility measurements indicated an interaction between molecules selected and cyclodextrins in water. These inclusion complexes are 1:1 with βCD, and HP-βCD. The values of K s showed a different kind of complexes depending on which rings are included. AM1 and DFT calculations were performed to obtain the optimized geometries, theoretical hyperfine constants, and spin distributions, respectively. The theoretical results are in complete agreement with the experimental ones.

Potentiometric study of binary complexes of methyl 2-pyridyl ketone oxime, phenyl 2-pyridyl ketone oxime and diacetyl monooxime with some transition and heavy metal ions in aqueous solution

The complexation reaction between some oximes including methyl-2-pyridylketone oxime (MPKO), phenyl-2-pyridylketone oxime (PPKO) and diacetyl monooxime (DMO) with some transition and heavy metal ions Co 2+, Ni 2+, Zn 2+, Pb 2+, Fe 2+, Fe 3+, Cr 3+ and La 3+ has been studied potentiometrically in aqueous solution at 25 ± 0.1 °C and ionic strength ( μ) of 0.1 M supported by KCl. The overall stability constants log β's of respective species were obtained by computer refinement of pH–volume data using BEST program. The best model among the several proposed models was selected according to the lowest σ fit value. The main species in binary systems are ML, ML 2, MLH, MLH 2, ML 2H, ML 2H 2, MOHL, M(OH) 2L, M(OH)L 2 and M(OH) 2L 2 (L = MPKO or PPKO or DMO).