Bases In Benzene Research Articles

Diarylgallium complexes derived from azo-linked Schiff bases: Synthesis, characterization and photoluminescence studies

Diarylgallium complexes of composition, [Ar2GaOC6H3(N=NPh)(CH=NAr’)], (Ar = Ph or tol; Ar’ = Ph, tol-4 or C6H4Br-4) have been synthesized by treatment of triaryl-gallium dioxane adduct with azo linked salicylaldimine Schiff bases in benzene. These complexes have been characterized by elemental analysis, IR, UV-Vis, NMR (1H and 13C{1H}) spectroscopy. The molecular structures of [Ph2GaOC6H3(N=NPh)(CH=NPh)] (2a) and [Ph2GaOC6H3(N=NPh)(CH=Ntol-4)] (2b) were established by X-ray crystallography. The complexes are discrete monomer with four coordinated gallium atom forming a distorted tetrahedral structure. Photoluminescence studies of these complexes showed that the quantum yield is always higher than that of the corresponding ligands and the emission peaks of complexes are blue shifted with respect to ligand.

Synthesis, Characterization, Photophysical and DFT Studies of Coumarin Schiff Bases and Their Dimethylgallium Complexes

Reactions of trimethyl gallium ether adduct with five different coumarin Schiff bases in benzene yielded dimethyl gallium complexes of the general formula [Me2Ga{–O–(C9H3O–(2-O)–(4-Me))–CH=N–R}] (R = tBu, C6H5, C6H4Me-4, C6H4Cl-4 and C6H4Br-4). These complexes have been characterized by elemental analysis, IR, UV–vis, NMR (1H and 13C{1H}) spectroscopy. The molecular structures of three gallium complexes, viz. [Me2Ga{–O–(C9H3O–(2-O)–(4-Me))–CH=N–C6H5}], [Me2Ga{–O–(C9H3O–(2-O)–(4-Me))–CH=N–C6H4Me-4] and [Me2Ga{–O–(C9H3O–(2-O)–(4-Me))–CH=N–C6H4Br-4] were unequivocally established by single crystal X-ray crystallography. The gallium atom acquires a distorted tetrahedral geometry. These complexes exhibit emission in the visible region and their emission maxima are blue shifted with respect to that of the corresponding free ligand. DFT calculations reveal that the HOMO–LUMO gap value becomes slightly smaller with electron withdrawing substituent like Cl and Br.

Synthesis, characterization, photoluminescence and computational studies of mono- and diorgano-gallium complexes containing azo linked salicylaldimine Schiff bases

The reactions of triorgano-gallium etherate with azo linked salicylaldimine Schiff bases in benzene gave complexes of the type [R2GaOC6H3(NNPh) (CHNAr)], [R2GaOC6H3(NNPh) (CHNCH2–)]2, [{R2GaOC6H3(NNPh) (CHNCH2CH2}3N] and [C6H5–NN–C6H3(4′-OGaRO)-3′-CHN–C6H4] (R = Me or Et; Ar = Ph or tol-4). These complexes have been characterized by elemental analysis, IR, UV–Vis, NMR (1H and 13C{1H}) spectroscopy. The molecular structures of [Me2GaOC6H3(NNPh)CHNPh]·½C6H6 (5a·½C6H6) and [Me2GaOC6H3(NNPh) (CHNtol-4)] (5c) were established by X-ray crystallography. Density functional calculations have also been performed to obtain structure and energetic information for the bare ligands and the metal-ligand complexes. Photoluminescence studies of these complexes showed that the quantum yield is always higher than that of the corresponding ligands and the emission peaks of complexes are blue shifted with respect to ligand.

Kinetics of proton transfer from tetra(4-nitro-5-tert-butyl)phthalocyanine to nitrogen-containing bases in benzene

The acid-basic interaction between tetra(4-nitro-5-tert-butyl)phthalocyanine and pyridine, 2-methylpyridine, morpholine, piperidine, n-butylamine, diethylamine, and triethylamine in benzene is studied. It is found that the intermolecular transfer of protons of NH groups from tetra(4-nitro-5-tert-butyl)phthalocyanine to morpholine and diethylamine is characterized by unusually low values of the reaction constant rates. The effect of the structure of tetra(4-nitro-5-tert-butyl)phthalocyanine and tetra(3-nitro-5-tert-butyl)phthalocyanine, and of the nature of the base on the kinetic parameters of acid-base interaction is demonstrated. A structure is proposed for complexes with the transfer of displaced phthalocyanines’ protons. It is found that they undergo decomposition over time.

Kinetics of proton transfer from hexa(m-trifluoromethylphenyl)benzotetraazaporphine to nitrogen-containing bases in benzene

Acid-base interactions of hexa(m-trifluoromethylphenyl)benzotetraazaporphine with pyridine, 2-methylpyridine, morpholine, benzylamine, piperidine, n-butylamine, diethylamine, triethylamine, and tert-butylamine in benzene are studied. It is found that intermolecular proton transfer from the NH groups of hexa(m-trifluoromethylphenyl)benzotetraazaporphine to n-butylamine and piperidine is characterized by unusually low values of rate constants. The effect of the structure of hexa(m-trifluoromethylphenyl)benzotetraazaporphine and octa(m-trifluoromethylphenyl)tetraazaporphine, and the nature of the base on the kinetic parameters of acid-base interactions, is demonstrated. A structure for proton-transfer complexes of substituted tetraazaporphines is proposed. It is found that they decompose over time.

The kinetics of proton transfer from octaphenylsubstituted tetraazaporphyrin to organic bases in benzene

The acid-base interaction of octa(m-trifluoromethylphenyl)tetraazaporphin with pyridine, 2-methylpiridine, morpholine, benzylamine, piperidine, n-butylamine, diethylamine, tert-butylamine, and triethylamine in benzene was studied. It was found that intermolecular transfer of spatially screened NH-group protons from octa(m-trifluoromethylphenyl)tetraazaporphin to morpholine, benzylamine, piperidine, n-butylamine, and tert-butylamine is characterized by unusually low values of rate constants. The effect of the structure of octa(m-trifluoromethylphenyl)tetraazaporphin, octa(n-bromophenyl)tetraazaporphin, octa(n-bromophenyl)tetraazaporphin, and octa(n-nitrophenyl)tetraazaporphin, and the nature of a base on the kinetic parameters of acid-base equilibrium is shown. A structure for complexes with proton transfer of octaphenylsubstituted tetraazaporphirins is suggested. It is revealed that they are subject to decomposition over time with the formation of low molecular colorless products.

Kinetic features of acid-base interaction of tetra(3-nitro-5-tert-butyl)phthalocyanine with nitrogen-containing bases in benzene

The kinetics of the reaction of acid-base interaction of tetra(3-nitro-5-tert-butyl)phthalocyanine with cyclic and acyclic nitrogen-containing bases in benzene was studied. The process is found to proceed with a low rate. The schemes of acid-base interaction are proposed and the probable structure of the proton transfer complexes of tetra(3-nitro-5-tert-butyl)phthalocyanine are discussed. The effect of the nature of the nitrogencontaining base on the kinetic parameters of the process is revealed.

Coordination properties of zinc 5,15-di(ortho-aminophenyl)octaalkylporphyrin in reactions with mono- an dibasic nitrogen bases

The coordination properties of zinc 5,15-di(ortho-aminophenyl)octaalkylporphyrin in reactions with mono- and dibasic nitrogen bases in benzene are studied by means of computational modeling and spectrophotometric titration. The stability of molecular zinc porphyrinate complexes in solution is estimated and their structure is determined. The correlation between the coordination properties of the compound under investigation and electronic and conformational factors of the macrocycle is established. The base nature is shown to affect the stability of zinc porphyrinate complexes. The correlations between the calculated σ bond energy of the zinc atom with the nitrogen atom of the base (E b) and the equilibrium constant of the axial coordination reaction are obtained. It is demonstrated that the reaction is accompanied by an increase in steric hindrance and a change in the type of deformation of the porphyrin ligand.

Diorganogallium Complexes Containing Tripodal Schiff Bases: Synthesis and Structure of [N{Me2GaO(C6H4)CH=N–CH2–CH2-}3

Treatment of triorganogallium etherates with tripodal Schiff bases in benzene gave complexes of composition [N{R2GaO(C6H3X)CH=N–CH2–CH2–}3] (R = Me, Et; X = H, OMe) in nearly quantitative yield. The molecular structure of [N{Me2GaO(C6H4)CH=N–CH2–CH2–}3] revealed that there are two different types of molecules in the crystal lattice each containing three distorted tetrahedral gallium atoms.

Ruthenium(II) unsymmetrical N2O2 tetradentate Schiff-base complexes: synthesis, characterization, and catalytic studies

A series of six-coordinate ruthenium(II) complexes [Ru(CO)(L x )(B)] (B = PPh3, AsPh3 or Py; L x = unsymmetrical tetradentate Schiff base, x = 5–8; L5= salen-2-hyna, L6= Cl-salen-2-hyna, L7= valen-2-hyna, L8= o-hyac-2-hyna) have been prepared by reacting [RuHCl(CO)(EPh3)2(B)] (E = P or As) with unsymmetrical Schiff bases in benzene under reflux. The new complexes have been characterized by analytical and spectroscopic (infrared, electronic, 1H, 31P, and 13C NMR) data. An octahedral structure has been assigned for all the complexes. The new complexes are efficient catalysts for the transfer hydrogenation of ketones and also exhibit catalytic activity for the carbon–carbon coupling reactions.

The kinetic peculiarities of intermolecular proton transfer from NH groups of octa(m-trifluoromethylphenyl)tetraazaporphin in the nitrogen base-benzene system

The acid-base interaction of octa(m-trifluoromethylphenyl)tetraazaporphin with nitrogen bases in benzene was studied. The rates of intermolecular transfer of sterically screened NH group protons from octa(m-trifluoromethylphenyl)tetraazaporphin to n-butylamine and tert-butylamine were found to be low. A scheme of the process was suggested. The influence of the nature of bases on the kinetic parameters of acid-base interactions was studied.

Kinetics of acid-base interaction of octaphenyl-substituted tetraazaporphyrins with nitrogen-containing bases in a system benzene-dimethylsulfoxide

Effect of dimethylsulfoxide additives on the kinetics of acid-base interaction of octaphenyl-substituted tetraazaporphyrins with nitrogen-containing bases in benzene is studied. A strong effect of the solvent on the process rate and activation parameters is revealed. The relation of the molecular structure of the interacting molecules to their reactivity is demonstrated.

Mononuclear Ru(III) Schiff base complexes: Synthesis, spectral, redox, catalytic and biological activity studies

An octahedral ruthenium(III) Schiff base complexes of the type [RuX(EPh 3)(L)] (where, X = Cl/Br; E = As/P; L = dianion of the Schiff bases derived from acetoacetanilide with o-phenylenediamine and salicylaldehyde/ o-hydroxyacetophenone/ o-vanillin/2-hydroxy-1-naphthaldehyde) have been synthesized from the reactions of equimolar reactions of [RuX 3(EPh 3) 3] and Schiff bases in benzene. The new Ru(III) Schiff base complexes have been characterized by elemental analyses, FT-IR, electronic, 1H NMR and 13C NMR spectra, EPR spectral studies, powder X-ray diffraction (XRD) and electrochemical studies. The new complexes were found to be effective catalysts for aryl–aryl coupling and the oxidation of alcohols into their corresponding carbonyl compounds, respectively, using molecular oxygen atmosphere at ambient temperature. Further, the new Ru(III) Schiff base complexes were screened for their antibacterial activity against Pseudomonas aeruginosa, Vibrio cholera, Salomonella typhi and Staphylococcus aureaus.

Synthesis, spectral, characterization, catalytic and biological studies of new RuII N2O Schiff base complexes

Complexes of the type [RuCl(CO)(B)(L)] (B = PPh 3 , AsPh 3 , py or pip; L = monobasic tridentate Schiff base) have been synthesized by the reaction of equimolar amounts of [RuHCI(CO)(EPh3) 2 (B)] and Schiff bases in benzene. The resulting complexes have been characterized by analytical and spectral (IR, electronic, NMR) data. An octahedral structure has been assigned to all these complexes. The new complexes have been exhibit catalytic activity for the oxidation of benzyl alcohol and cyclohexanol in the presence of N-methylmorpholine-N-oxide as co-oxidant.

Synthesis and Characterization of Samarium (III) Tris(O,O′ -Dialkyl and Alkylene Dithiophosphates) and Their Adducts with Nitrogen and Phosphorus Donor Bases

Samarium (III) tris(dithiophosphates, [SmS2P(OR)2 3.3H2O] (where R = ─CH2CH2CH3 or ─C6H5) and [SmS2PO2G3.3H2O] [where G = ─C(CH3)2CH2CH(CH3)─, ─CH2C(CH3)2CH2-, ─C(CH3)2C(CH3)2-, ─CH2CH2CH(CH3), ─CH2C(C2H5)2CH2-, and ─CH(CH3)CH(CH3)-], were prepared by a reaction of SmCl3.6H2O and ammonium dithiophosphates in distilled water. Adducts of the type [SmS2P(OR)2 3.nL] and [SmS2PO2G3.nL] [where n = 1, L = N2C10H8 and n = 2, L = P(C6H5)3] were prepared by a reaction of samarium (III) tris(dithiophosphates) and nitrogen or phosphorus donor bases in benzene. These newly synthesized compounds have been characterized by elemental analysis, molecular weights measurement, thermogravimetric analysis, UV-visible, IR, and 1H and 31P NMR spectral studies. Coordination numbers of eight and nine are suggested for samarium (III) in these derivatives.

Synthesis, spectral, catalytic and antimicrobial studies of PPh 3/AsPh 3 complexes of Ru(II) with dibasic tridentate O, N, S donor ligands

Complexes of the type [Ru(CO)(EPh 3)(B)(L)] (E = P or As; B = PPh 3, AsPh 3, py or pip; L = dianion of the Schiff bases derived from thiosemicarbazone with acetoacetanilide, acetoacet- o-toluidide and o-chloro acetoacetanilide) have been synthesized from the reactions of equimolar amounts of [RuHCl(CO)(EPh 3) 2(B)] and Schiff bases in benzene. The new complexes have been characterized by analytical and spectral (IR, electronic, NMR) data. The arrangement of PPh 3 groups around ruthenium metal was determined from 31P NMR spectra. An octahedral structure has been assigned for all the new complexes. All the complexes exhibited catalytic activity for the oxidation of benzyl alcohol and cyclohexanol in presence of N-methylmorpholine- N-oxide as co-oxidant. The complexes also exhibited antibacterial activity against E. coli, Aeromonas hydrophilla and Salmonella typhi. The activity was compared with standard streptomycin.

Kinetic characteristics of intermolecular proton transfer from NH groups of tetra(3-nitro-5-tert-butyl)phthalocyanine in nitrogen base-benzene systems

The kinetics of acid-base interaction between tetra(3-nitro-5-tert-butyl)phthalocyanine and cyclic and acyclic nitrogen bases in benzene was studied. The reaction was found to occur with a low rate. The structure and reactivity of protolytes were shown to be interrelated. The structure and stability of the proton-transfer complexes formed are considered.

Synthesis, characterization, electro chemistry, catalytic and biological activities of ruthenium(III) complexes with bidentate N, O/S donor ligands

New hexa-coordinated ruthenium(III) complexes of the type [RuX2(EPh3)2(L)] (E=P or As; X=Cl or Br; L=monobasic bidentate Schiff base derived from the condensation of benzhydrazide with furfuraldehyde, 2-acetylfuran and 2-acetylthiophene) have been synthesized from the equimolar amounts of [RuX3(EPh3)3] or [RuBr3(PPh3)2(MeOH)] and Schiff bases in benzene. The new complexes have been characterized by analytical, spectral (IR, electronic and EPR), magnetic moment, and cyclic voltammetry. An octahedral structure has been tentatively proposed. All the complexes have exhibited catalytic activity for the oxidation of benzyl alcohol, cyclohexanol and cinnamylalcohol in the presence of N-methylmorpholine-N-oxide as co-oxidant. All the new complexes were found to be active against the bacteria such as E. coli, Pseudomonas, Salmonella typhi and Staphylococcus aureus. The activity was compared with standard Streptomycin.

Synthesis, characterization and catalytic studies of ruthenium(II) Schiff base complexes

Complexes of the type [Ru(CO)(EPh3)(B)(L)] (E = P or As; B = PPh3, AsPh3, py or pip; L = dianion of the Schiff bases derived from the condensation of salicyloyl hydrazide with acetone, ethyl methyl ketone and salicylaldehyde have been synthesised by the reaction of equimolar amounts of [RuHCl(CO)(EPh3)2(B)] and Schiff bases in benzene. The resulting complexes have been characterized by analytical and spectral (i.r., electronic, n.m.r.) data. The arrangements of Ph3P groups around the Ru metal was determined from 31P-n.m.r. spectra. An octahedral structure has been assigned to all the new complexes. All the complexes exhibit catalytic activity for the oxidation of benzyl alcohol and cyclohexanol in the presence of N-methylmorpholine-N-oxide as co-oxidant.

Experimental and theoretical studies on the functionalization reactions of 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carboxylic acid and acid chloride with 2,3-diaminopyridine.

The 1H-pyrazole-3-carboxylic acid 2 was converted in good yield (69%) into the corresponding 1H-pyrazole-3-carboxamide 5 via reaction of the acid chloride 3 with 2,3-diaminopyridine (4). A different product, the 3H-imidazo[4,5-b] pyridine derivative 6, was formed from the reaction of 3 with 4 and base in benzene for 5 hours. The structures of the synthesized compounds were determined spectroscopically. The mechanism of the reaction between 3 and 4 was examined theoretically.