Synthesis and spectral studies ofo-hydroxyacetophenone (N-benzoyl)glycyl hydrazone and some of its lanthanide(III) complexes

Summary o-Hydroxyacetophenone (N-benzoyl)glycyl hydrazone (o-HABzGH) has been characterized by i.r.,¹H n.m.r.,¹³C n.m.r. and mass spectral studies, and its complexes of the types [Ln(o-HABzGH)Cl₂(H₂O)₂]Cl and [Ln(o-HABzGH–2H)OH(H₂O)₃], where Ln=La, Pr, Nd, Sm and Eu, have been synthesized. The structures of the complexes have been studied by conductance, magnetic, electronic, i.r.,¹H n.m.r. and¹³C n.m.r. spectral techniques. The hypersensitive bands of the electronic spectra suggest coordination numbers six and seven around Nd^III in its adduct and neutral complexes respectively. I.r. and n.m.r. spectral data suggest a neutral bidentate behaviour for the ligand in the adducts and a dinegative tridentate nature in the neutral complexes.     

Copper(II) and nickel(II) complexes of 2-formylpyridine 3-piperidinyl-, 3-hexamethyleneiminyl- and 3-azabicyclo[3.2.2]nonylthiosemicarbazones

Summary Copper(II) and nickel(II) complexes of 2-formylpyridine 3-piperidinyl-, 3-hexamethyleneiminyl- and 3-azabicyclo-[3.2.2]nonylthiosemicarbazones were prepared and characterized spectroscopically. ¹H and ¹³C n.m.r. spectra of the thiosemicarbazones and a diamagnetic nickel(II) complex are reported, together with i.r., electronic and e.s.r. spectra of the metal complexes. The thiosemicarbazones and their copper(II) and nickel(II) complexes exhibit considerable growth inhibitory activity against Paecilomyces variotii, but show minimal activity against Aspergillus niger.     

Carbon-13 n.m.r. and CNDO/S study of 1,3-indandione and heterocyclic analogues

¹³C n.m.r. spectra are reported for 1,3-indandione, phthalic anhydride, thiophthalic anhydride, and phthalimide in chloroform-d solution. The ¹³C chemical shifts have also been calculated by means of Pople's perturbation theory using CNDO/S wave functions; the agreement between theoretical and experimental values is improved when an empirical charge-dependent term is added to the calculated diamagnetic and paramagneitc contributions.     

Metal-proton interactions in palladium(II) and rhodium(I) complexes ofortho-alkylanilines

Summary Reaction of 1 equivalent ofo-alkylaniline with Pd(OAc)₂ gave the acetate bridged complexes [Pd(OAc)₂L]₂. The^*H n.m.r. spectra showed downfield shifts for theo-benzylic protons indicating an above-plane geometry involving a significant interaction with the metal orbitals. Similar interactions were found for Pd(OAc)₂L₂ and Pd(OAc)₂L(L) (L= differento-alkylaniline; t-butylpyridineetc.) prepared from the dimer and for Rh(CO)₂Cl(L) complexes. Theo-benzylic carbons of the palladium complexes did not show downfield shifts in the¹³C n.m.r. spectra.     

Synthesis and characterization of new dioxomolybdenum(VI) complexes of ONS donor Schiff bases derived from thiosemicarbazide,S-methyldithiocarbazate,S-benzyldithiocarbazate ando-hydroxy-aromatic aldehydes/ketones

Summary Syntheses of several new dioxomolybdenum(VI) complexes with composition MoO₂L · MeOH (where LH₂ = Schiff base derived from salicylaldehyde, 2-hydroxy-1-naphthaldehyde,o-hydroxyacetophenone,o-hydroxybenzophenone, pyridoxal and thiosemicarbazide,S-methyldithiocarbazate orS-benzyldithiocarbazate) are reported. The complexes have been characterized by elemental analysis, i.r., n.m.r. and electronic spectra, conductance, molecular weight and magnetic susceptibility measurements. The complexes are monomers, nonelectrolytes, diamagnetic and six-coordinated. The Schiff bases behave as dibasic tridentate ligands and coordinate through phenolic oxygen, thioenolic sulphur and azomethine nitrogen atoms. The complexes have acis-O=Mo=O structure as evidenced by the presence of two strong bands at 880–915 and 925–955 cm^–1. All of the complexes exhibit a band atca. 25000 cm^–1 due to the ligand to metal charge transfer transition.     

Structural elucidation of o-vanillin isonicotinoyl hydrazone and its metal complexes

Summary A new series of complexes with the tridentate dibasic Schiff base ligand o-vanillin isonicotinoyl hydrazone (o-VINH) were prepared and characterized by i.r., ¹H n.m.r. and electronic spectral studies, magnetic susceptibility measurements and t.g.a. The disappearance of low field signals due to OH, NH protons at 10.23 and 9.31 p.p.m. and downfield shift of the –CH=N proton signal at 8.17 p.p.m. in the n.m.r. spectrum confirms the involvement of these groups in coordination. Both t.g.a. and i.r. spectral data show evidence for one molecule of coordinated H₂O. These results taken in conjunction with electronic spectral data allow assignation of tetrahedral geometry for manganese(II), nickel(II) and palladium(II) complexes but a square planar configuration to cobalt(II), copper(II) amd zinc(II) complexes.     

Pteridine studies: III—13C n.m.r. data of pteridine,some of its derivatives and their covalent σ-adducts with ammonia and water

¹³C n.m.r. spectral data of pteridine and nineteen of its derivatives (containing one or more chloro, methylthio, methyl, t-butyl or phenyl substituents) are reported. The ¹³C n.m.r. spectrum of the title compound has been assigned conclusively. ¹³C n.m.r. substituent effects are shown to be very useful in discerning between 6- and 7-substituted pteridines. Additionally, the ¹³C n.m.r. spectra of several covalent amination products, i.e. the 3,4-dihydro-4- amino- and the 5,6,7,8-tetrahydro-6,7-diaminopteridine derivatives, formed by dissolving the appropriate pteridine in liquid ammonia, have been recorded. The ¹³C n.m.r. spectra of the corresponding covalent hydrates are also reported.     

Study of Electron Donor–Acceptor Complex Formation of o-Chloranil With a Series of Phosphine Oxides and Tri- n-butyl Phosphate by the Absorption Spectrometric Method

Electron donor–acceptor (EDA) complex formation of o-chloranil with six different phosphine oxides and tri-n-butyl phosphate (TBP) has been studied in CCl ₄ solution by the UV-VIS absorption spectrophotometric technique. An absorption band due to a charge–transfer (CT) transition is observed in the visible region. Utilizing the CT transition energy, the electron affinity of o-chloranil in solution has been calculated. Degrees of charge transfer, and oscillator and transition dipole strengths have also been calculated for all of the investigated EDA complexes. Except for TBP, other phosphine oxides, viz., tri-n-octyl phosphine oxide, tri-n-butyl phosphine oxide, triphenyl phosphine, octyl(phenyl)-N,N-diisobutylcarbamoylphosphine oxide, octyl(phenyl)-N,N-dicyclohexylcarbamoylmethylphosphine oxide and octyl(phenyl)-N,N-diisopropylcarbamoylmethylphosphine oxide have been shown to form stable 1:1 EDA complexes with o-chloranil. The complex of TBP with o-chloranil decays slowly into a secondary product. Formation constants of the EDA complexes have been determined.     

New vic-dioxime transition metal complexes

New vic-dioxime ligands and their Cu^II, Co^III, Ni^II and VO^IV complexes have been prepared and characterized by elemental analyses, i.r. and u.v. spectra, magnetic moments and molar conductance data. The Co^III complexes are diamagnetic. The ¹H- and ¹³C-n.m.r. and g.c./m.s. spectra of the vic-dioxime ligands and their Co^III complexes were recorded. The compounds are all non-electrolytes.     

Complexation of palladium cyanide with imidazolidine-2-thione and its derivatives

Summary Pd(CN)₂ reacts with imidazolidine-2-thione (Imt), 1,3-diazinane-2-thione(Diaz), 1,3-diazipnane-2-thione (Diap) and their derivatives to yield complexes of stoichiometry [PdL₂(CN)₂] or [PdL(CN)₂] (L = Imt, Diaz or Diap and L = Imt having N-Me, Et or Pr substituents), which were characterized by elemental analysis, i.r., ¹H and ¹³C n.m.r. spectroscopy. Both mono- and bis ligand complexes are thought to be square planar with the monoligand binding to metal via sulphur (bridging) and the bis ligand via the monodentate thione group. The ¹³C enriched Pd(¹³CN)₂ complex was prepared and the ¹³C n.m.r. recorded. The C-2 resonance of ¹³C n.m.r. of Imt, Diaz or Diap complexes of the copper(I), silver(I), gold(I) and palladium(II) were compared.     

13C n.m.r. spectra of some thiobenzamides. Correlation between 13C and 1H n.m.r. spectra and signal assignments of syn and anti CH2 groups

¹³C n.m.r. spectra of a series of N,N-disubstituted thioamides have been recorded and signal assignments were performed. Separate signals are observed for methylene groups fixed on the nitrogen atom. Since the carbon atom syn to the thiocarbonyl sulfur resonates at higher field than the anti carbon, the syn-anti assignment in ¹H n.m.r. is easily obtained by selective double irradiation. This method, which is rapid and reliable, affords a rather general solution to the interesting problem of resonance assignments in tertiary amides and thioamides (and in analogous molecules such as oximes and nitrosamines).     

13C n.m.r. spectroscopy: Comparison of the spectra of some dimeric Catharanthus alkaloids and their derivatives

The ¹³C n.m.r. spectra of some dimeric Catharanthus alkaloids are reported and assigned. Methods devised to aid in the assignment of resonances in complex molecules are described. The ¹³C n.m.r. spectra of several derivatives of vinblastine are discussed.     

The novel azomethine ligands for binuclear copper(II) complexes with ferro- and antiferromagnetic properties

A series of novel binuclear ferro- and antiferromagnetic Cu(2+) chelates of structurally broadly varied Schiff bases (derived from o-tosylamino(hydroxyl)benzaldehydes and monoalkylated o-phenylenediamine, o-aminophenol, o-aminothiophenol, 1,2-diaminobenzimidazole, 1-aminobenzimidazoline-2-thione) and β-diketimines (derived from 2,6-di-i-Pr-aniline) has been prepared. The tautomerism of the ligands and structureof their copper complexes have been studied with the use of IR, ¹H NMR EPR and EXAFS spectroscopy. Molecular and crystal structure of a β-diketimine copper dimer has been determined by X-ray crystallography. The magnetic measurements (2–300?K) performed for all the complexes showed that the ferro- and antiferromagnetic character of the exchange interaction depends both on the structure of the coordination site (origin of the ligating centers) and the structure of the ligands (in particular, on the type of the cycle annelated to the bridging fragment). Whereas S-binding metal chelates 13 (X?=?NTs, Y?=?S, R?=?H) are diamagnetic, the complexes 15 with annelated azole moieties are ferromagnetic.     

1H- und 13C-NMR-untersuchungen an dibromoxabicyclo[n.2.1]alkanen

The ¹H n.m.r. spectra of some dibromooxabicyclo[n.2.1]alkanes are discussed for the determination of the configuration and conformation. The ¹³C n.m.r. spectra confirm the observed stereochemistry. With increasing ring size the ¹³C n.m.r. chemical shifts of the hetero atom substituted C-atoms C-1 and C-2 move steadily to lower fields.     

Nuclear magnetic resonance spectral study of 2-acetylpyridine4 N-alkylthiosemicarbazones and their cobalt(III) complexes

¹H and¹³C n.m.r. spectra are reported for a series of 2-acetylpyridine⁴ N-alkylthiosemicarbazones in order to study the effect of increased size of the alkyl function on the ratio of isomers present in solution. Similarly, n.m.r. data for the bis(thiosemicarbazone)cobalt(III) complexes are included, as well as these complexes' ligand field parameters. TMC 2698     

Carbon-13 N.m.r. and I.r. Studies of copper(I) complexes of the — NHCS group in five- and six-membered heterocyclic rings

Summary Crystalline copper(I) complexes of the general formula [LCuCl] and [L₂CuCl] were prepared for imidazolidine-2-thiones and 1,3-diazinane-2-thiones by the reduction of copper(II) halides with an excess of the ligands. The¹³C n.m.r. and i.r. spectra of these complexes are consistent with thione sulphur (ligand) donation in all cases. The magnitude of the high-field shift in the¹³C resonance of the thioureide carbon in the complexes as compared with that of the free ligands is interpreted in terms of coordination geometry around the metal atoms. A comparison of the chemical shifts for gold(I), silver(I) and copper(I) revealed a displacement ofca. 6–8 ppm for the mono- and 2–4 ppm for the bis-complexes, respectively.     

1H and 13C studies of alkenes,epoxides and cyclic thionocarbonates

¹H and ¹³C chemical shift data are presented and discussed for a number of di- and tri-alkyl substituted alkenes, epoxides and thionocarbonates. The completely stereospecific interconversion of these compounds, together with the n.m.r. data, allows a straightforward and quantitative stereochemical analysis. For ¹H n.m.r., the most useful intermediates proved to be the thionocarbonates. The differential shieldings between cis and trans isomers are tentatively explained in terms of the conformational change of the 5-membered thionocarbonate ring. In ¹³C n.m.r., either series can be useful to distinguish between stereoisomers. The conclusions stemming from the ¹³C n.m.r. results complement the ¹H n.m.r. studies.     

Diamagnetic contribution and substituent effects on 13C n.m.r. spectra

Correction of measured chemical shifts by subtracting the diamagnetic contributions caused by certain substituents on various carbons of a molecule leads to data that allow a reasonable interpretation of substituent effects on chemical shifts in ¹³C n.m.r. spectroscopy. It is shown that both paramagnetic and diamagnetic terms increase on all carbons of a molecule when the atomic number of a substituent increases down the same group of the periodic table. An explanation of α-, β-, and γ- effects for methyl substitution using the same procedure is attempted.     

Magnetic and spectroscopic properties of copper(II) complexes with 1-salicoyl-4-phenylthiosemicarbazide

Summary Cu^II complexes of 1-salicoyl-4-phenylthiosemicarbazide (SPT) have been synthesized and characterized by means of elemental analysis, magnetic measurements, and i.r. and e.p.r. spectroscopic methods; ¹H- and ¹³C-n.m.r. and mass spectral data on the thiosemicarbazide are also reported. A paramagnetic complex _eff= 1.298 B.M., is formed with copper(II) sulphate; the low magnetic moment and the e.p.r. spectral data suggest a binuclear species. A diamagnetic complex due to a strong Cu-Cu interaction has been isolated with copper(II) chloride.     

1H and 13C n.m.r. study of butatriene-bis-tricarbonyliron complexes. Assignment of geometric orientation by comparative J(CCCH) values

A number of substituted butatriene-bis-tricarbonyliron complexes have been studied by ¹³C and ¹H n.m.r. spectroscopy. Long range coupling values, J(CCCH), have confirmed chemical shift results that methyl and phenyl groups assume opposite orientations at the coordinated double bonds with the methyl group preferentially trans to carbon and the phenyl group preferentially trans to iron.