Formamide Complexes Research Articles

Phosphinsubstituierte Chelatliganden, IV [1] Neue Diphenylphosphinoformamid-Komplexe des Mangans und Eisens / Phosphine Substituted Chelate Ligands, IV [1] New Diphenylphosphino Formamide Complexes of Manganese and Iron

The phosphino and (thio)phosphoryl formamides 1a, b, 2a-c, 3a, b, 4a, b which were partially unknown are synthesized by various methods, and their reactions with carbonylmetal halides of manganese and iron are described. The formation of the P,N- and S,N coordinate chelate complexes, (CO)4MnL (5 a, 8a), is limited to the N-phenyl derivatives la and 4a. With L = 2a, b, the unidentate P-coordination predominates. Thus, the carbonylmetal halide complexes cis-(CO)4Mn(X)L (6a, b: X = CI, 7a, b: X = Br) and η5-C5H5(CO)Fe(X)L (9a, b: X = I, 10a, b: X = Br) are obtained. Due to the low stability of the formamide complexes, their formation is always accompanied by isocyanate elimination as a side-reaction

ChemInform Abstract: INFRARED, RAMAN, AND CNDO STUDIES OF THE EFFECT OF IONS ON THE ELECTRON DENSITY DISTRIBUTION IN FORMAMIDE

Abstract Infrared and Raman spectra of electrolyte solutions in formamide have been investigated for amide I and CH stretching regions. The effects of the cation-molecule and anion-molecule interactions on the frequency shift and IR intensity are discussed in terms of CNDO/2 calculations performed for the model formamide complexes with Li+ and F− ions. It is suggested that the considerable CH frequency shift upon cornplexing with cation is due to the trans lone pair effect.

Infrared, Raman, and cndo studies of the effect of ions on the electron density distribution in formamide

Infrared and Raman spectra of electrolyte solutions in formamide have been investigated for amide I and CH stretching regions. The effects of the cation-molecule and anion-molecule interactions on the frequency shift and IR intensity are discussed in terms of CNDO/2 calculations performed for the model formamide complexes with Li + and F − ions. It is suggested that the considerable CH frequency shift upon cornplexing with cation is due to the trans lone pair effect.

Dilute solution properties of sodium cellulose disulphate

Sodium cellulose sulphate (NaCaS), with degree of substitution (DS) of 1.90, was synthesized by reacting samples of cellulose, covering a wide range of average molecular weight, with S03/dimethyl formamide complex. A solution of NaCS in 0.5 M aq. NaCl was studied by solution viscometry, light scattering and membrane osmometry. The solution was dialysed against solvent. The following MarkHouwink-Sakurada equation and relation between the z-average radius of gyration and weightaverage molecular weight, Mw, were established for 7.2 × 10 4 ⩽ M w ⩽ 1.5 × 10 6 at 25° .The NaCS with salt system was analysed according to the theory of linear non-ionic polymers. Flory's viscosity parameter φ is significantly molecular weight dependent. The partially free draining effect and the excluded volume effect were estimated and the former predominated. The unperturbed chain can be regarded as Gaussian and its dimension A was found to be 1.21 × 10 −8 cmand the conformation parameter a was 2.9.

Hydrogen‐bond cooperativity in protein secondary structure

AbstractHydrogen bonding in the α‐helix and β‐sheet has been studied by ab initio molecular orbital calculations carried out on complexes of formamide. Hydrogen‐bond geometries were taken from x‐ray crystallography of polypeptides. Positive cooperativity is found in all cases. The limiting value for infinite chains is obtained by use of a double‐reciprocal plot and indicates an increase in the effective bond strength of 25% over that of a single isolated bond. Parallel calculations based on a classical electrostatic model yield qualitatively similar trends but underestimate the cooperativity by half. Charge redistribution accompanying cooperativity is characterized by a new type of charge‐density difference plot, the cooperativity map. The magnitude and distance over which cooperativity acts suggest several significant biological consequences. Thus the average of α‐helices and the number of β‐sheet strands found in protein may be influenced by cooperativity. Cooperativity in the interpeptide hydrogen bond may also be partly responsible for the rapid formation of secondary structure in renaturing proteins and help stabilize secondary structure relative to the random‐coil conformation.

Fluoro complexes of hexavalent uranium—VI adducts of dioxodifluorouranium (VI) with nitrogen and oxygen donor ligands

Adducts of uranyl fluoride of the types UO 2F 2·L·H 2O and UO 2F 2·L′ (where L = 2,2′-dipyridyl, 1, 10-phenathroline and 8-hydroxyquinoline; L′ = dimethyl sulphoxide, dimethyl formamide, pyridine, α-picoline and γ-picoline) have been prepared by mixing uranyl fluoride and the corresponding ligand in 1:1 mole ratio in 50% aqueous ethanolic medium. Two adducts with urea, viz. [UO 2F 2(urea)] and [UO 2F 2(urea) 2] have been obtained by reacting uranyl fluoride with urea in different mole ratios in dry methanolic medium. The molecular conductances of the complexes in methanol indicate their nonelectrolytic nature. IR spectral studies show that urea, dimethyl formamide and dimethyl sulphoxide complexes are oxygen bonded ones. Thermogravimetric analysis suggests that the dipyridyl, phenanthroline and oxine complexes contain coordinated water.

The effect of hydrogen bonding on the peptide linkage

On the basis of the results obtained in a series of structure investigations and a series of theoretical studies the effect of hydrogen bonding on the peptide linkage (the NCO moiety) is discussed. The structure determinations., using X-ray diffraction methods, comprise eight molecules which contain the NCO moiety. The theoretical studies have been carried out using ab initio methods with hydrogen bonded complexes of formamide as model systems. The effect of hydrogen bonding on the peptide linkage, i.e. the shortening of the CN bond and the lengthening of the CO bond, is well reflected by the theoretical calculations. These calculations indicate that the readily delocalized π-electronic system, which can counteract perturbations in the σ-electronic system, is one of the major factors in the ability of the peptide linkage to form hydrogen bonds. On the basis of the structural parameters obtained in the crystal structure determinations and those found in the gaseous state for some simple amides, it is found that the formation of one intermolecular NH… O hydrogen bond, i.e. such that both the nitrogen and oxygen atoms of the NCO moiety are involved, leads to a shortening of the CN bond by ∼ 0.025 Å and a lengthening of the CO bond by ∼ 0.014 Å

Preparation of Alkylsulfaces having Sulfur in the β-Position of Alkyl Group

The sulfation reactions of long chain alkyl primary alcohols having sulfur in the β-position by various sulfating agents were studied. 2-Alkylsulfinylethanol was reacted with strong sulfating agents, i.e., chlorosulfonic acid or sulfur trioxide to give 2-alkylsulfinylethyl sulfate in 6373% yield, whereas 2-alkylmercaptoethanol was not sulfated with such strong acids but sulfated with weak acids, i.e., sulfamic acid-dimethyl formamide or sulfamic acid-urea complex to give 2-alkylmercaptoethyl sulfate in 7387% yield. 2-Alkylsulfonylethanol was also reacted with weak sulfating agents to give 2-alkylsulfonylethyl sulfate in high yield but in lower yield with strong sulfating agents.The stabilities toward hydrolysis of sodium 2-alkylmercapto, sulfinyl, sulfonylethyl sulfates were compared with those of sodium alkyl sulfates. Under acidic conditions, these alkyl sulfates having S, SO and SO2 groups in the β-position behaved almost similaly to alkyl sulfates, but under basic conditions, they were rapidly hydrolyzed to mainly alkyl vinyl sulfide, sulfoxide and sulfone respectively along with small amounts of the corresponding alcohols.

The I.R. Spectra of Interlamellar Kaolinite-Amide Complexes—I. The Complexes of Formamide, N-Methylformamide and Dimethylformamide

AbstractThe i.r. spectra of interlamellar kaolinite complexes with formamide, N-methylformamide and dimethylformamide have been examined. The spectra show that the amides hydrogen-bond, through the C=O group of the amide to the inner surface kaolinite hydroxyls and decrease the intensity of the kaolinite ν(OH) bands. Hydrogen-bonded kaolinite hydroxyl bands appear at lower frequencies and these have been correlated to the original kaolinite ν (OH) bands. Other kaolinite bands in the complexes show smaller perturbations of the kaolinite vibrations. Each amide hydrogen-bonds to different groups of hydroxyls. Formamide hydrogen-bonds to the 3690 and 3664 cm−1 hydroxyls, N-methylformamide to the 3690 and 3648 cm−1 hydroxyls. The interpretation for the dimethylformamide complex is less clear. The ν(NH) frequencies of formamide and N-methylformamide in the complexes are intermediate between that in dilute non-polar solution and in the liquid. This could arise from either or both a degree of intermolecular association of the amide when between the kaolinite lamellae, or to weak N—H … O hydrogen bonds to the tetrahedral oxygen sheet of the lamellae.

Dimethyl and diphenyl formamide complexes of lanthanide perchlorates

N,N-Dimethyl formamide (DMF) and N,N-diphenyl formamide (DPF) complexes of six lanthanide perchlorates of the composition M(DMF)8(ClO4)3 and M(DPF)6(ClO4)3 where M = La, Ce, Pr, Nd, Sm, or Y have been prepared and characterized. The infrared spectra show that the amide is bonded to the metal through oxygen. Conductivity, molecular weight, and spectral studies indicate coordination numbers of eight and six for DMF and DPF complexes respectively, with the perchlorate groups remaining ionic.

Dimethyl sulphoxide and dimethyl formamide complexes of Mn(III) perchlorate

Dimethyl sulphoxide (DMSO) and dimethyl formamide (DMF) complexes of Mn(III) perchlorate have been prepared and their conductivity, magnetic susceptibility and i.r. and electronic spectra studied. The complexes behave as uni-trivalent electrolytes in acetonitrile. Their magnetic moments of 5·1 B.M. show them to be of high spin type. Infra-red spectra show that oxygen is the donor atom in both complexes. The spin allowed electronic transition for d 4 system, around 20,000 cm −1, ascribable to the 5E g → 5T 2g transition, suggests an octahedral configuration for these complexes

The dimethyl formamide – acyl halide complex and its application to the synthesis of acyl azides

A description of the conditions which favor the formation of the acid chloride – dimethyl formamide complex is given. The utility of the complex is illustrated by its application to the synthesis of acyl azides and, in particular, by the selective formation of 3-bromopropionyl azide from the corresponding acid chloride. The complex also results from a carboxylic acid salt and N,N-dimethyl chloroformiminium chloride, and thus provides an alternative method of effecting the direct conversion of a carboxylic acid into the corresponding acid azide.

Dimethyl formamide complexes of rare-earth nitrates

Dimethyl formamide complexes of five rare-earth nitrates, M(DMF) 4(NO 3) 3 where M = La, Pr, Nd, Sm or Y have been prepared and their infra-red spectra and conductivities in nitromethane and DMF studied. It is suggested that the co-ordination number of the metal ion in these complexes is nine.