Synthesis and structural characterization of manganese(III,IV) and ruthenium(III) complexes derived from 2-hydroxy-1-naphthaldehydebenzoylhydrazone

Reaction of 2-hydroxy-1-naphthaldehydebenzoylhydrazone(napbhH₂) with manganese(II) acetate tetrahydrate and manganese(III) acetate dihydrate in methanol followed by addition of methanolic KOH in molar ratio (2 : 1 : 10) results in [Mn(IV)(napbh)₂] and [Mn(III)(napbh)(OH)(H₂O)], respectively. Activated ruthenium(III) chloride reacts with napbhH₂ in methanolic medium yielding [Ru(III)(napbhH)Cl(H₂O)]Cl. Replacement of aquo ligand by heterocyclic nitrogen donor in this complex has been observed when the reaction is carried out in presence of pyridine(py), 3-picoline(3-pic) or 4-picoline(4-pic). The molar conductance values in DMF (N,N-dimethyl formamide) of these complexes suggest non-electrolytic and 1 : 1 electrolytic nature for manganese and ruthenium complexes, respectively. Magnetic moment values of manganese complexes suggest Mn(III) and Mn(IV), however, ruthenium complexes are paramagnetic with one unpaired electron suggesting Ru(III). Electronic spectral studies suggest six coordinate metal ions in these complexes. IR spectra reveal that napbhH₂ coordinates in enol-form and keto-form to manganese and ruthenium metal ions in its complexes, respectively. ESR studies of the complexes are also reported.     

Synthesis and spectral characterization of homobimetallic molybdenum(VI) complexes derived from bis(2-hydroxy-1-naphthaldehyde)succinoyldihydrazone

The reaction of bis(2-hydroxy-1-naphthaldehyde)succinoyldihydrazone with bis(acetylacetonato)dioxomolybdenum(VI) (MoO₂(acac)₂) in 1 : 3 molar ratio in EtOH : water mixture (95 : 5) affords a complex of composition [(MoO₂)₂(nsh)(H₂O)₂] · C₂H₅OH. The reaction of [(MoO₂)₂(nsh)(H₂O)₂] · C₂H₅OH with Lewis bases, namely pyridine, 2-picoline, 3-picoline, and 4-picoline, yields [(MoO₂)₂(nsh)(B)₂] · C₂H₅OH (where B = pyridine, 2-picoline, 3-picoline, and 4-picoline). Further, when this complex was reacted with 1,10-phenanthroline and 2,2′-bipyridine in 1 : 3 molar ratio in anhydrous ethanol the binuclear complexes [(μ₂-O)₂(MoO₂)₂(H₄nsh)(phen)] · C₂H₅OH and [(μ₂-O)₂(MoO₂)₂(H₄nsh)(bpy)] · C₂H₅OH were obtained. All of the complexes have been characterized by analytical, magnetic moment, and molar conductivity data. The structures of the complexes have been discussed in the light of electronic, IR, ¹H NMR, and ¹³C NMR spectroscopy.     

Synthesis,characterization, reactivity,and electrochemical studies of manganese(IV) complexes of bis(2-hydroxy-1-naphthaldehyde)adipoyldihydrazone

Manganese(IV) complexes [Mn^IV(npah)(H₂O)₂] (1) and [Mn^IV(npah)(A)₂]?·?nH₂O (where A?=?py (2), 2-pic (3), 3-pic (4), 4-pic (5)) and Mn^IV(npah)(NN)] (NN?=?bpy (6) and phen (7)) have been synthesized from bis(2-hydroxy-1-naphthaldehyde)adipoyldihydrazone in methanol. The composition of the complexes has been established by elemental analyses. Complex 3 has been characterized by mass spectral data also. Structural assessment of the complexes has been based on data from molar conductance, magnetic moment, electronic, electron paramagnetic resonance, and infrared (IR) spectral studies. Molar conductances of the complexes in DMSO suggest non-electrolytes. Magnetic moment and EPR studies suggest +4 oxidation state for manganese in these complexes. Electronic spectral studies suggest six-coordinate octahedral geometry around the metal ions. IR spectra reveal that H₄npah coordinates to the metal in enol form. Reaction of the complexes with benzyl alcohol and SO₂ has been investigated. Cyclic voltammetric studies of the complexes have also been carried out.     

Synthesis and characterization of molybdenum(V,VI) complexes derived from bis(2-hydroxy-1-naphthaldehyde)malonoyldihydrazone

Monometallic molybdenum(VI) complexes [MoO₂(CH₂LH₂)]?·?H₂O (1), [Mo₂O₄(CH₂LH₂)₂(A)₂] (A?=?py (2), 2-pic (3), 3-pic (4) and 4-pic (5)) and molybdenum(V) complexes [Mo(CH₂LH₂)(inh)]?·?H₂O (6) and [Mo(CH₂LH₂)(slh)] (7) of bis(2-hydroxy-1-naphthaldehyde)malonoyldihydrazone (CH₂LH₄) have been synthesized and characterized by various physico-chemical and spectroscopic studies. The compositions of the complexes have been established by elemental analyses and molecular weight determination. The structural assessment of the complexes has been done on the basis of data obtained from molar conductances, magnetic moment studies, electronic, infrared, electron paramagnetic resonance (EPR), proton nuclear magnetic resonance, and ¹³C proton nuclear magnetic resonance spectroscopic studies. The molar conductance values for the complexes in DMSO suggest that they are non-electrolytes. The magnetic moment values for 6 and 7 correspond to one unpaired electron while the remaining complexes are diamagnetic. Complexes 1, 6, and 7 have six-coordinate octahedral stereochemistry around molybdenum, while 2–5 are eight-coordinate dodecahedral around the metal centers. EPR spectral features suggest that 7 is less symmetrical than 6.     

Synthesis and spectral studies on heterobimetallic complexes of manganese and ruthenium derived from N-(2-hydroxynaphthalen-1-yl)methylenebenzoylhydrazide

The complex [Mn^IV(napbh)₂] (napbhH₂ = N-(2-hydroxynaphthalen-1-yl)methylenebenzoylhydrazide) reacts with activated ruthenium(III) chloride in methanol in 1 : 1.2 molar ratio under reflux, giving heterobimetallic complexes, [Mn^IV(napbh)₂Ru^IIICl₃(H₂O)] · [Ru^III(napbhH)Cl₂(H₂O)] reacts with Mn(OAc)₂·4H₂O in methanol in 1 : 1.2 molar ratio under reflux to give [Ru^III(napbhH)Cl₂(H₂O)Mn^II(OAc)₂]. Replacement of aquo in these heterobimetallic complexes has been observed when the reactions are carried out in the presence of pyridine (py), 3-picoline (3-pic), or 4-picoline (4-pic). The molar conductances for these complexes in DMF indicates 1 : 1 electrolytes. Magnetic moment values suggest that these heterobimetallic complexes contain Mn^IV and Ru^III or Ru^III and Mn^II in the same structural unit. Electronic spectral studies suggest six coordinate metal ions. IR spectra reveal that the napbhH₂ ligand coordinates in its enol form to Mn^IV and bridges to Ru^III and in the keto form to Ru^III and bridging to Mn^II.     

Synthesis and properties of mononuclear and binuclear molybdenum complexes derived from bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone

The monomer molybdenum(VI) complex [MoO(2)(napoxlhH(2))].2H(2)O (1) has been synthesized from the reaction of MoO(2)(acac)(2) with bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone (napoxlhH(4)) in 1:1 molar ratio in ethanol under reflux. This complex on reaction with pyridine/3-picoline/4-picoline yielded the dimer molybdenum(VI) complexes [Mo(2)O(4)(napoxlhH(2))(2)(A)(2)].2H(2)O (A=py (2), 3-pic (3), 4-pic (4)), whereas reaction with isonicotinoylhydrazine (inhH(3)) and salicyloylhydrazine (sylshH(3)) lead to the reduction of the metal centre yielding monomeric molybdenum(V) complexes [Mo(napoxlhH(2))(hzid)].2H(2)O (where hzidH(3)=inhH(3) (5) and sylshH(3) (6)). The complexes have been characterized by elemental analyses, molecular weight determinations, molar conductance data, magnetic moment data, electronic, IR, ESR and (1)H NMR spectroscopic studies. The complexes (5) and (6) are paramagnetic to the extent of one unpaired electron. The electronic spectra of the complexes are dominated by strong charge transfer bands. In all of the complexes, the principal dihydrazone ligand has been suggested to coordinate to the metal centres in the anti-cis-configuration. The complexes (1), (5) and (6) are suggested to have six-coordinate octahedral stereochemistry around molybdenum(VI) and molybdenum(V) metal centres, respectively, while the complexes (2)-(4) are suggested to have eight coordinate dodecahedral stereochemistry around molybdenum(VI) metal centre.     

Synthesis and spectral studies on heterobimetallic complexes of manganese and ruthenium derived from bis[N-(2-hydroxynaphthalen-1-yl)methylene]oxaloyldihydrazide

The complex [Mn(L)(H₂O)₂] [H₄L = bis[N-(2-hydroxynaphthalen-1-yl)methylene]-oxaloyldihydrazide] reacts with activated ruthenium(III) chloride in methanol in 1:1.2 M ratio under reflux resulting in heterobimetallic complex of the composition [Mn(L)(H₂O)₄RuCl₂]Cl. The complexes of the composition [Mn(L)(A)₄RuCl₂]Cl were obtained when the above reaction was carried out in presence of heterocyclic nitrogen bases(A) such as pyridine(py), 3-picoline(3-pic) and 4-picoline(4-pic). The molar conductance values for these complexes in DMF(N,N-dimethyl formamide) solution indicate their 1:1 electrolytic nature. Magnetic moment values suggest that these heterobimetallic complexes contain Mn(IV) and Ru(III) in the same structural unit. Electronic spectral studies suggest six coordinated metal ions in these complexes. IR spectra reveal that the H₄L ligand coordinates in its keto-form to Mn(IV) and Ru(III).     

Synthesis, characterization and photophysics of bimetallic manganese(I) and ruthenium(II) complexes

A series of new manganese(I) and ruthenium(II) monometallic and bimetallic complexes made of 2,2′-bipyridine and 1,10-phenanthroline ligands, [Mn(CO)₃(NN)(4,4′-bpy)]⁺, [{(CO)₃(NN)Mn}₂(4,4′-bpy)]²⁺ and [(CO)₃(NN)Mn(4,4′-bpy)Ru(NN)₂Cl]²⁺ (NN = 2,2′-bipyridine, 1,10-phenanthroline; 4,4′-bpy = 4,4′-bipyridine) are synthesized and characterized, in addition to already known ruthenium(II) complexes [Ru(NN)₂Cl(4,4′-bpy)]⁺ and [Cl(NN)₂Ru(4,4′-bpy)Ru(NN)₂Cl]²⁺. The electrochemical properties show that there is a weak interaction between two metal centers in Mn–Ru heterobimetallic complexes. The photophysical behavior of all the complexes is studied. The Mn(I) monometallic and homobimetallic complexes have no detectable emission. In Mn–Ru heterobimetallic complexes, the attachment of Mn(I) with Ru(II) provides interesting photophysical properties.     

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 X_{4? n} (R?=?Me, Ph, ⁿ Bu or Cy; n?=?1–3) acceptors and Li[L₂CS₂]. Mononuclear complexes of the type [L₂CS₂]R _n SnCl_{4? 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 and characterization of binuclear manganese(IV,IV) and mononuclear cobalt(II) complexes based on 2-(2-hydroxyphenyl)-1H-benzimidazole

The bidentate benzimidazolic hpbm (1), [2-(2-hydroxyphenyl)-1H-benzimidazole], was obtained under mild conditions, and its corresponding metal complexes, di-µ-oxo dimanganese(IV,IV) [Mn₂O₂(hpbm)₄ · 2Py · 5H₂O] (2), and mononuclear complex [Co(hpbm)₂] (3), were prepared and characterized. The crystal structures of 2 and 3 have been established by X-ray diffraction. Complex 2 consists of two six-coordinate manganese(IV) coordinated to two hpbm ligands and bridged by two O^2? with a Mn–Mn distance of 2.777 Å. For 3, a Co(II) is coordinated to two deprotonated hpbm in a nearly tetrahedral environment. Hydrogen bonds play pivotal roles in constructing the dimensional structures of both the compounds.     

Synthesis,spectral, thermal and crystallographic investigations on oxovanadium(IV) and manganese(III) complexes derived from heterocyclic β-diketone and 2-amino ethanol

Novel mononuclear oxovanadium(IV) and manganese(III) complexes [VO(L¹)₂·H₂O] (1); [VO(L²)₂·H₂O] (2); [VO(L³)₂·H₂O] (3); [Mn(L¹)₂]ClO₄·H₂O (4); [Mn(L²)₂] ClO₄·H₂O (5); [Mn(L³)₂]ClO₄·H₂O (6) were prepared by condensation of 1 mol of VOSO₄·5H₂O or Mn(OAc)₃· 2H₂O with 2 mol of ligand HL¹, HL² or HL³ (where HL¹ = 4-[(2-hydroxy-ethylamino)-methylene]-5-methyl-2- phenyl-2,4-dihydro-pyrazol-3-one; HL²=4-[(2-hydroxy-ethylamino)-methylene]-5-methyl-2-p-tolyl-2,4-dihydro-pyrazol-3-one; HL³=4-{4-[(2-hydroxy-ethyl-amino)-methyl]-3-methyl-5-oxo-4,5-dihydropyrazol-1-yl} benzene sulfonic acid). The resulting complexes were characterized by elemental analyses, molar conductance, magnetic and decomposition temperature measurements, electron spin resonance, FAB mass, IR and electronic spectral studies. From TGA, DTA and DSC, the thermal behaviour and degradation kinetic were studied. Electronic spectra and magnetic susceptibility measurements indicate distorted octahedral stereochemistry of oxovanadium(IV) complexes and regular octahedral stereochemistry of manganese(III) complexes. Hamiltonian and bonding parameters found from ESR spectra indicate the metal ligand bonding is partial covalent. The X-ray single crystal determination of one of the representative ligand was carried out which suggests existence of amine-one tautomeric form in the solid state. The ¹H-NMR spectra support the existence of imine-ol form in solution state. The LC-MS studies sustain the¹H-NMR result. The electronic structure of the same representative ligand was optimized using 6-311G basis set at HF level ab initio studies to predict the coordinating atoms of the ligand.     

Heterobimetallic dioxomolybdenum(VI) complexes derived from bis(2-hydroxy-1-naphthaldehyde)malonoyldihydrazone: Synthesis and characterization

The heterobimetallic complexes [MMoO₂(L)(H₂O)₂] (where M = Zn²⁺ (1), Cu²⁺ (2), and Co²⁺ (4)) and [{MMoO₃(H₂L)(H₂O)₂}₂] (where M = Ni²⁺ (3) and Mn²⁺ (5)) are synthesized from bis(2-hydroxy-1-naphthaldehyde)malonoyldihydrazone (H₄L) using the monometallic precursor complex [MoO₂(H₂L)]·H₂O in ethanol. The composition of the complexes is established based on the data obtained from the elemental analysis and molecular weight determinations. The structure of the complexes is discussed in the light of data obtained from molar conductance, magnetic moment, electronic, EPR and IR spectroscopic studies.     

Synthesis and characterization of a mononuclear ruthenium(III) triazole complex

A mononuclear ruthenium(III) complex containing ethylenediaminetetraacetate (edta), [Ru(Hedta)(Htrz)] · 4H₂O (1) (Htrz = 1H-1,2,4-triazole), has been synthesized and the structure was determined by single-crystal X-ray diffraction. The complex crystallizes in the triclinic space group P 1, with the unit cell parameters a = 7.212(3) Å, b = 9.873(4) Å, c = 13.806(6) Å, α = 91.945(6)°, β = 100.078(6)°, γ = 97.230(7) and Z = 2. The complex was also characterized by elemental analysis, IR, UV–Vis and ESR spectra. Cyclic voltammetry for the complex shows a ruthenium(III)/ruthenium(IV) oxidation and a ruthenium(III)/ruthenium(II) reduction within the range of ?1.5–0.5 V. Magnetic susceptibility data give an effective moment of 1.81 B.M. at room temperature.     

Synthesis and characterization of new organotin(IV) complexes with polyfunctional ligands

New mono-, di- and tri-organotin(IV) derivatives containing the neutral bis(2-pyridylthio)methane ligand, [(pyS)₂CH₂] and tris(2-pyridylthio)methane ligand, [(pyS)₃CH] have been synthesized from reaction with SnR_nCl_4−n (R = Me, ⁿBu, Ph and Cy, n = 1-3) acceptors. Mono-nuclear adducts of the type {[(pyS)₂CH₂]R_nSnCl_4−n} and {[(pyS)₃CH]R_nSnCl_4−n} have been obtained and characterized by elemental analyses, FT-IR, ESI-MS, multinuclear (¹H and ¹¹⁹Sn) NMR spectral data. The ¹H and ¹¹⁹Sn NMR and ESI-MS data suggest for the triorganotin(IV) derivatives a complete dissociation of the compounds in solution. The mono- and di-organotin(IV) derivatives show a greater stability in solution, and their spectroscopic data are in accordance with the existence of six-coordinated RSnCl₃N₂ or R₂SnCl₂N₂ species.     

Synthesis and spectral studies of nickel(II) complexes derived from disalicylaldehyde oxaloyldihydrazone

The mononuclear nickel(II) complex [Ni(H₂slox)(H₂O)₃] (1) and polymeric dinuclear complexes [Ni₂(slox)(A₄)] {A = H₂O (2), py (3), 2-pic (4), 3-pic (5) and 4-pic (6)} and the discrete binuclear complexes [Ni₂(slox)(NN)₃] {NN = bpy (7) and phen (8)} have been synthesized from disalicylaldehyde oxaloyldihydrazone (H₄slox) in methanol. All of the complexes are nonelectrolytes. Complexes 1, 7, and 8 are paramagnetic while binuclear 2–6 possess anomalously low μ _eff value, indicating considerable metal–metal interaction. Discrete binuclear 7 and 8 have no interaction between the two nickel(II) ions. The anomalously low magnetic moment values in 2–6 are explained as metal–metal interaction via phenoxide bridge. Such metal–metal interactions are less in 7 and 8 due to coordination of bipyridine and phenanthroline molecules which do not allow phenoxide bridging. The dihydrazone coordinates to the metal center as a dibasic tridentate ligand in keto-enol form in staggered configuration in 1, while in the remaining complexes the dihydrazone is tetrabasic hexadentate in enol form in anticis configuration. The metal center has a tetragonally distorted octahedral stereochemistry.     

Synthesis, spectroscopic characterization, X-ray structure and DFT calculations of rhenium(III) complex with bis(3,5-dimethylpyrazol-1-yl)methane

[ReCl₃(MeCN)(PPh₃)₂] reacts with bis(3,5-dimethypyrazol-1-yl)methane (bdmpzm) in acetone to give [ReCl₃(bdmpzm)(PPh₃)]. The compound has been studied by IR, UV–Vis spectroscopy and X-ray crystallography. The molecular orbital diagram of [ReCl₃(bdmpzm)(PPh₃)] has been calculated with the density functional theory (DFT) method.     

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)₂CHCO₂], 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_nCl_4−n (R = Me, Ph and ⁿBu, n = 1-2) acceptors and Na[(pyS)₂CHCO₂]. Mono-nuclear complexes of the type {[(pyS)₂CHCO₂]R_nSnCl_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.     

Lanthanide(III) complexes of N-salicylideneglycine and N-(2-hydroxy-1-naphthylidene) glycine

New lanthanide(III) complexes of N-salicylideneglycine and N-(2-hydroxy-1-naphthylidene) glycine have been prepared and characterized by elemental analytical, molar conductance, and IR and UV-visible spectral data. Both the ligands (H₂L) have been found to act as monobasic tridentate towards lanthanide ions, yielding complexes of the type [Ln(HL)₂(NO₃)] and [Ln(HL)₂(Cl)(H₂O)]. The spectral data reveal that the HL moiety is bonded to the central atom through its phenolic oxygen, imine nitrogen and a carboxylate oxygen, and that the nitrato group acts as bidentate. From the observed pattern of hypersensitivef-f bands, octacoordination is construed.