Synthesis,thermal and electrical studies on solvated oxovanadium(IV) complexes with schiff bases derived from aromatic diamines and 2-hydroxy-1-naphthaldehyde

Summary Solvated oxovanadium(IV) complexes of Schiff bases derived from aromatic diamines and 2-hydroxy-1-naphthaldehyde have been prepared from ethanolic medium. The elemental analyses reveal that the complexes have the ratio 1:1, 2:2 and 1:2 (ligand:metal) composition which are nonelectrolyte inDMF. The coordination number six (octahedral geometry) is proposed for the complexes prepared. This is based on the results of IR, electronic and EPR spectra. TGA as well as DTA studies and the electrical properties and (I–V) characteristics for the metal complexes were investigated.

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Synthese und thermische bzw. elektrochemische Untersuchungen an solvatisierten Oxovanadium(IV)-Komplexen mit Schiff-Basen aus aromatischen Diaminen und 2-Hydroxy-1-naphthaldehyd

Zusammenfassung Die im Titel genannten Komplexe wurden in ethanolischem Medium hergestellt. Sie sind inDMF Nichtelektrolyte und haben laut Elementaranalyse die Zusammensetzung Ligand:Metall=1:1, 2:2 und 1:2. Basierend auf IR-, UV- und EPR-Spektren wird die Koordinationszahl 6 (oktahedrale Geometrie) vorgeschlagen. Es wurden TGA- und DTA-Studien durchgeführt und das elektrochemische Verhalten der Metallkomplexe untersucht.

     

Tin(IV) complexes ofSchiff bases derived from salicylaldehyde and aminoalcohols

11 and 12 molar reactions of tin(IV) chloride with theSchiff bases, HO–C₆H₄CHNROH [where R=–(CH₂)₂–, –CH₂–, –CH(CH₃)–, –(CH₂)₃–, and –CH(C₂H₅)CH₂–] have been studied in different stoichiometric ratios and derivatives of the type SnCl₄(SBH₂) and SnCl₄(SBH₂)₂ (whereSBH₂ represents theSchiff base molecule) have been isolated. These have been characterised by elemental analysis, conductivity measurements and I.R. spectral studies.     

Synthesis and characterization of manganese(IV) and ruthenium(III) complexes derived from bis (2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone

Bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone(naohH₄) interacts with manganese(II) acetate in methanol followed by addition of KOH giving [Mn^IV(naoh)(H₂O)₂]. Activated ruthenium(III) chloride reacts with naohH₄ in methanol yielding [Ru^III(naohH₄)Cl(H₂O)Cl₂]. The replacement of aquo by heterocyclic nitrogen donor in these complexes has been observed when the reaction is carried out in presence of heterocyclic nitrogen donors such as pyridine(py), 3-picoline(3-pic) or 4-picoline(4-pic). The molar conductance values in DMF for these complexes suggest non-electrolytic nature. Magnetic moment values suggest +4 oxidation state for manganese in its complexes, however, ruthenium(III) complexes are paramagnetic with one unpaired electron. Electronic spectral studies suggest six coordinate metal ions. IR spectra reveal that naohH₄ coordinates in enol-form and keto-form to manganese and ruthenium, respectively. ESR and cyclic voltammetric studies of the complexes have also been reported.     

Ruthenium(II) complexes containing triphenylphosphine/triphenylarsine and bidentate Schiff bases derived from 2-hydroxy-1-naphthaldehyde and primary amines

The synthesis and characterisation of some new hexa-coordinated Schiff base complexes of the type [RuCl(CO)(EPh₃)(B)(L)] (E = P or As; B = PPh₃ or AsPh₃ or py or pip; L = anion of the Schiff bases derived from 2-hydroxy-1-naphthaldehyde and aniline, 4-chloroaniline or 2-methylaniline) are reported. I.r., electronic, ¹H-n.m.r, ³¹P-n.m.r. spectra, catalytic activity and antibacterial activity of the complexes are discussed. An octahedral structure has been tentatively proposed for all the complexes.     

Copper(II) complexes of schiff bases derived from tryptamine and hydroxyketones or hydroxydiketones

Summary Cu^II complexes of Schiff bases derived from tryptamine/ hydroxyketone or hydroxydiketone condensation have been prepared and characterized by mass spectrometry. i.r., visible-ultraviolet and¹H n.m.r. spectroscopy and by magnetic moments.     

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 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.     

Characterization of heterobimetallic and mixed-valence complexes of molybdenum(V) derived from bis(2-hydroxy-1-naphthaldehyde) malonoyldihydrazone

Heterobimetallic complexes [UO₂Mo^V(CH₂L)(hzd)(H₂O)₂] _n , [ZnMo^V(CH₂L)(hzd)(H₂O)₂] _n and mixedvalence complexes [Mo^VIO₂Mo^V(CH₂L)(hzd)(H₂O)₂] _n (where hzdH₃ = inhH₃, n = 1; slhH₃, n = 2) are synthesized from bis(2-hydroxy-1-naphthaldehyde)malonoyldihydrazone (CH₂LH₄) and monometallic precursor complexes [Mo(CH₂LH₂)(hzd)]·nH₂O (n = 0, 1) in ethanol. The composition of the complexes is established based on the data obtained from the elemental analysis. The structure of the complexes is discussed in the light of data obtained from molar conductance, magnetic moment, electronic, EPR, and IR spectroscopic studies. All complexes have ??B values in the range 1.59?C1.64 B.M., slightly lower than that required for one unpaired electron. The heterobimetallic complexes show two bands, while mixed-valence complexes show only one band in the visible region assigned to the d-d transition. The g-values decrease in going from uranyl-to-molybdenyl-to-zinc complexes containing the isonicotinoyldiazenido (inh) group, however, no such regular trend is observed in the case of complexes containing the salicyloyldiazenido (slh) group in the coordination sphere. In all complexes, the principal dihydrazone ligand is present in the enol form as a bridging hexadentate ligand in the anti-cis configuration where hydrazide ligands are coordinated to the metal centre as a trinegative bidentate ligand in the diazenido form.     

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 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.     

Synthetic, structural and biological studies of organotin(IV) complexes of schiff bases derived from pyrrol-2-carboxaldehyde

Some new organotin(IV) complexes having general formulae R₂MCl[L] and R₂M[L]₂ were synthesized by the reactions of Me₂MCl₂ with Schiff bases [5-Mercapto-4-(pyrrolcarboxalideneamino)-s-triazole, 5-Mercapto-3-methyl-4-(2-pyrrolcarboxalideneamino)- s-triazole, 3-Ethyl-5-mercapto-4-(2-pyrrolcarboxalideneamino)-s-triazole] in 1:1 and 1:2 molar ratios. All of the compounds were characterized by elemental analysis, molar conductance, IR, UV, ¹H, ¹³C and ¹¹⁹Sn NMR spectral studies. The IR and ¹H NMR spectral data suggest the involvement of azomethine nitrogen in coordination with the central metal atom. With the help of the above-mentioned spectral studies, penta and hexacoordinated environments around the central metal atoms in the 1:1 and 1:2 complexes, respectively, have been proposed. Finally, the free ligands and their metal complexes were tested in vitro against some pathogenic bacteria and fungi to assess their antimicrobial properties.     

Tin(IV), titanium(IV) and hafnium(IV) complexes of some aromatic Schiff bases derived from 4-aminoantipyrine

Summary Tin(IV), titanium(IV) and hafnium(IV) chloride complexes of ligands such as salicylidene-4-aminoantipyrine (HL¹), 5-chlorosalicylidene-4-aminoantipyrine (HL²), 2,4-dihydroxybenzylidene-4-aminoantipyrine (HL³), 2-hydroxy-1-naphthylidene-4-aminoantipyrine (HL⁴) and 2-hydroxyacetophenonylidene-4-aminoantipyrine (HL⁵) have been prepared and characterized. The analytical data show that tin(IV) forms only 1:1 metal complexes when reacted with HL¹, HL³ and HL⁴, whereas it forms 1:1 and 1:2 metal complexes when reacted with HL², depending on the molar ratio. HL⁵ produces only the binuclear complex SnHL⁵Cl₄(H₂O)SnCl₄. Titanium(IV) gives only one type of complex of the general formula [Ti(HL)₂Cl₂]Cl₂-2H₂O, whilst hafnium(IV) gives HfHL³Cl₄-4H₂O and Hf(L⁵)₂Cl₂.     

Characterization of technetium-99m complexes of pentane-2,4-dione bis(N-methylthiosemicarbazone)

Further characterization of the two neutral technetium-99m (99mTc) complexes of pentane-2,4-dione bis-(N-methylthiosemicarbazone) (PETS) was carried out using a new dianionic PETS derivative, 3,3-dimethyl-pentane-2,4-dione bis(N-methylthiosemicarbazone) (DM-PETS), and the well characterized 99mTc complex of 2,2,9,9-tetramethyl-4,7-diaza-1,10-decanedithiol (DADT) as references. While PETS generated two neutral 99mTc complexes, 99mTc-PETS-L1 and 99mTc-PETS-L2, by both the stannous reduction method and the ligand exchange reaction with six-coordinated 99mTc(V) complex of N,N'-ethylenebis(acetylacetone imine), DM-PETS formed only one neutral 99mTc complex. 99mTc-PETS-L2, the more lipophilic complex of the two 99mTc-PETS, was obtained with a much higher yield than 99mTc-PETS-L1 by the ligand exchange reaction of PETS with the five-coordinated 99mTc(V) complex of glucoheptonate. In addition, while 99mTc-PETS-L2 and 99mTc-DADT remained unchanged in the presence of CN- anions, a breakdown of the original complexes was observed in 99mTc-PETS-L1 and 99mTc-DM-PETS. All four 99mTc complexes exhibited similar brain, heart and pancreas extraction when injected into mice. These cumulative results imply that 99mTc-PETS-L1 and 99mTc-DM-PETS are six-coordinated mononuclear 99mTc(V) complexes and that 99mTc-PETS-L2 is a five-coordinated mononuclear 99mTc(V) complex. These results also suggest that while the chelate ring structure of the 99mTc-dithiosemicarbazone (DTS) chelate played a significant role in its stability, ionization of the third proton of the PETS molecule and the subsequent resonating structure afforded further stability to the 99mTc-PETS complex. Markedly high lipophilicity of the 99mTc-PETS-L2 may also be explained by assuming that 99mTc-PETS-L2 is the five-coordinated resonating structure.     

Magnetic and spectral properties of oxovanadium(IV) complexes of schiff bases derived from halo-substituted salicylaldehyde and aniline

The magnetic and spectral properties of oxovanadium(IV) complexes of bidentate monobasic NO donor Schiff bases derived from 5-chlorosalicylaldehyde, 5-bromosalicyl-aldehyde and aniline are reported. In contrast to an earlier report that the complexes are involved in antiferromagnetic exchange, magnetic, ESR and molecular weight data indicate that the complexes are magnetically dilute. The complexes are monomers. The ESR spectra of the complexes in chloroform solutions show 8-line spectra characteristic of oxovanadium(IV) complexes which are not involved in magnetic exchange. The complexes exhibit magnetic moments in the range 1.73–1.75 B.M. at ~ 295 K and obey the Curie-Weiss law with θ = 0 to + 2 K indicating the absence of magnetic ordering in the temperature range 83–296 K.The electronic and infrared spectral data of the complexes are also reported. In contrast to an earlier suggestion of dimeric structure, a monomeric structure with square-pyramidal geometry is suggested for the complexes.     

Complexes of titanium(IV), vanadium(IV) and tin(IV) with schiff bases derived from 2-(2-aminophenyl)benzimidazole

Summary New titanium(IV), vanadium(IV) and tin(IV) complexes with Schiff bases derived from 2-(2-aminophenyl)benzimidazole with benzaldehyde (L₁) and salicylaldehyde (L₂) have been prepared and have the general formulae MX₄ · 2L (M = Ti, V or Sn; L = L₁ or L₂; X = Cl or Br).All the complexes have been characterized by elemental analyses, magnetic measurements, e.p.r., electronic and i.r. spectral studies. The results show that the Schiff bases act as monodentate ligands. Tentative structures for the complexes are suggested.     

Polymeric complexes of bivalent transition metal ions with 2-hydroxy-1-naphthaldehyde oxaldihydrazone and 2-hydroxy-1-naphthaldehyde malondihydrazone

Summary Polymeric complexes prepared by solid-solution reactions, from 2-hydroxy-1-naphthaldehyde oxaldihydrazone (HNODH) and 2-hydroxy-1-naphthaldehyde malondihydrazone (HNMDH), had the empirical composition M(L-2H)·nH₂O where M=Fe^II, Mn^II, Co^II, Ni^II, Cu^II, Zn^II, Cd^II and Hg^II; L=HNODH, HNMDH andn=0,1, 2. The complexes, which are intensely coloured and insoluble in common organic solvents, were characterized by elemental analysis, magnetic susceptibility, electronic and i.r. spectral data. The absence of anions indicates that the ligands which bind the metal ions from the hydroxyl and the imino groups have been deprotonated.     

Novel platinum(II) and (IV) complexes of naphthaldimine schiff bases

Naphthaldimines containing N₂O₂ donor centers react with platinum(II) and (IV) chlorides to give two types of complexes depending on the valence of the platinum ion. For [Pt(II)], the ligand is neutral, [(H₂L¹)PtCl₂]·3H₂O (1) and [(H₂L³)₂Pt₂Cl₄]·5H₂O (3), or monobasic [(HL²)₂Pt₂Cl₂]·2H₂O (2) and [(HL⁴)₂Pt]·2H₂O (4). These complexes are all diamagnetic having square-planar geometry. For [Pt(IV)], the ligand is dibasic, [(L¹)Pt₂Cl₄(OH)₂]·2H₂O (5), [(L²)Pt₃Cl₁₀]·3H₂O (6), [(L³)Pt₂Cl₄(OH)₂]·C₂H₅OH (7) and [(L⁴)Pt₂Cl₆]·H₂O (8). The Pt(IV) complexes are diamagnetic and exhibit octahedral configuration around the platinum ion. The complexes were characterized by elemental analysis, UV-Vis and IR spectra, electrical conductivity and thermal analyses (DTA and TGA). The molar conductances in DMF solutions indicate that the complexes are non-ionic. The complexes were tested for their catalytic activities towards cathodic reduction of oxygen.