Alkylamine Complexes Research Articles

Morphology and Composition-Controls of Cu<I><SUB>x</SUB></I>S Nanocrystals Using Alkyl-Amine Ligands

Nearly monodispersed-size Cu x S nanocrystals(NCs) were obtained by sulfuration of Cu(II)-alkyl-amine complexes using dodecanethiol-solvated sulfur at 363 K. The morphology and chemical composition of Cu x S NCs can be controlled by using appropriate alkyl-amine ligands. NCs of Cu-deficient sulfides, Cu 1.8 S (digenite) or a Cu 1.8 S-Cu 2 S mixture, were obtained using octylamine or di-octylamine, while stoichiometric Cu 2 S NCs using tri-octylamine and oleylamine ligands.

Synthesis and examination of amine-cyanocarboxyboranes, the boron analogues of α-cyanocarboxylic acids: X-ray structural study of the first lactam containing a boron atom in the lactam ring

The first representatives of chiral boron atom-containing amine-cyanomethoxycarbonyl boranes (A · BH(CN)COOMe) have been synthesized either from the corresponding amine-bromocyanomethoxycarbonylborane complexes with [Bu 4N]CN or from Me 3N · BH(CN)COOMe and an amine in a base-exchange reaction. Acid hydrolyses of methyl esters generated the free acids (A · BH(CN)COOH), which are isoelectronic to the α-cyano carboxylic acids. Their p K a values and hydrolysis half-lives in acidic medium (that is rate of proton reduction) have been determined. Similarly to the alpha cyano carboxylic acids, the cyano group attached to the boron (in alpha position to the COOH group) increased the acid strength of carboxy boranes with 2.0–2.5 orders of magnitude. Independently from the type of the amine, p K a values of the amine-cyanocarboxyboranes (6.34–5.82) decrease consistently with the increase of p K b values of the amines. Hydrolytic decomposition rate of the alkylamine complexes increases with increasing p K b values of the amines while the opposite was found for pyridine base complexes. When considering both types of the amines, hydrolysis half-lives of the complexes range over several orders of magnitude from 0.005 to 400 h. Based on these observations protonation of the amine nitrogen atom appears to be the rate determining step in the hydrolysis process. With loss of methanol, 2-NH 2-py · BH(CN)COOMe transformed into a five membered lactam derivative. X-ray diffraction revealed that the pyridine ring is coplanar with the five membered lactam ring. In the crystal two molecules are connected in a head to tail arrangement by strong intermolecular H-bonds between N(2)–H and the carbonyl oxygen (O1) with a donor and acceptor distance of 2.867(3) Å. Three new cyanomethoxycarbonylborates having the composition of K[BH n (CN) 3− n COOMe] ( n = 1, 2) and K[B(OH)(CN) 2COOMe] have also been synthesized and their properties examined.

Fabrication of the Sponge-like Layered Silver(I)-alkylamine Complexes and Their in situ Reduction

Abstract A series of layer-structured silver(I)-alkylamine complexes with sponge-like morphology and abundant macroporosity were self-assembled in the alcohol/water system. After in situ reduction, the layered silver(0)-alkylamine composites were obtained.

Calculated molecular properties for different alkanoic acid–alkylamine complexes: A comparison with measured FTIR and Raman spectra

In this work the charges, geometries, changes in geometries due to complexation, stabilization energies and vibrational frequencies have been calculated for three different propanoic acid (A)–propylamine (B) complexes. The complexes are A 3B 1, A 1B 3 and A 2B 2. Furthermore, emphasis was given to clarifying which complex is the most stable one in binary solutions of alkanoic acid and alkylamine. The theoretically predicted vibrational spectra are compared with IR and Raman spectra for the binary system heptanoic acid–heptylamine. In theoretical calculations we have used Hartree–Fock and density function theory approximations. Calculations show the A 3B 1 complex to be the most stable one, which is also confirmed by the experiments at low amine concentrations. At equimolecular mixing ratios a A 2B 2 complex seems more likely.

Calculated and measured vibrational frequencies in an alkanoic acid–alkylamine complex

Calculated geometries, charges and harmonic frequencies have been obtained for a complex consisting of propanoic acid and propylamine in a molecular ratio of 3:1 using ab initio quantum-chemical methods. The calculated harmonic frequencies are compared with a Fourier transform infrared spectrum for a binary mixture of heptanoic acid and heptylamine in a molecular ratio of 3:1. Except for the oxygen–hydrogen stretching vibration in the hydroxyl group of the unionized acids, there is a good correlation between the calculated and measured frequencies.

Charge-transfer spectroscopy and photochemistry of alkylamine cobalt(III) complexes

Spectroscopic and photochemical studies are reported for Co(NH 2R) 6 3+, Co(NH 2R) 5OH 2 3+, and Co(NH 2R) 5X 2+ (where R is methyl, ethyl, or n-propyl, and X is Cl − or Br −). These complexes absorb strongly in the ultraviolet region owing to the presence of one or more ligand-to-metal charge transfer (LMCT) band(s). Irradiation into this charge transfer region results in redox decomposition of the complex with the release of Co 2+, alkylamine, and a radical. Photoredox quantum yields measured in fluid solution are generally high and dependent upon excitation wavelength, oxygen concentration, temperature, and solution viscosity. In contrast to their well-studied ammine analogues, the alkylamine complexes (1) possess a N → Co charge transfer band at wavelengths well above 200 nm, (2) undergo redox decomposition from the X → Co and N → Co charge transfer excited states, and (3) avoid an intermolecular decomposition pathway involving photooxidation of the solvent. Reasons for these differences between the two families of complexes are discussed.

(Fluoroalkyl)phosphine complexes of rhodium and iridium. Synthesis and reactivity properties of [(dfepe)Ir(.mu.-Cl)

The synthesis, structure, and reactivity properties of iridium and rhodium (fluoroalkyl)phosphine dimeric complexes [(dfepe)M([mu]-Cl)][sub 2] (dfepe = (C[sub 2]F[sub 5])[sub 2]PCH[sub 2]CH[sub 2]P(C[sub 2]F[sub 5])[sub 2]; M = Rh (1); M = Ir (2)) are described. Complexes 1 and 2 are prepared in high yield from the displacement of cyclooctadiene from [(cod)M([mu]-Cl)][sub 2]. X-ray diffraction studies reveal that 1 and 2 are isomorphous with identical M[sub 2]([mu]-Cl)[sub 2] dihedral hinge angles of 128[degrees]. Complexes 1 and 2 exhibit higher thermal stability and do not undergo oxidative addition reactions with H[sub 2], O[sub 2], or alkyl halides. Although chloride abstraction or aklylation of 2 was unsuccessful, CpIr(dfepe) was prepared in good yield from the reaction of 2 with TlCp in refluxing THF. Addition of both donor and acceptor ligands to 2 produces monomeric products. Treatment of 2 with excess diethylamine affords (dfepe)Ir(NEt[sub 2]H)Cl (4), a surprisingly stable alkylamine complex which has been structurally characterized. Carbonylation reactions of both 1 and 2 are concentration- and solvent-dependent. In dilute acetone solutions, (dfepe)M(CO)Cl products are observed (M = IR (5), v(CO) = 2076 cm[sup [minus]1]; M = Rh (6), v(CO) = 2093 cm[sup [minus]1]), which could not be isolated due to reversible CO lossmore » in the absence of a CO atmosphere. At higher solution concentrations dfepe loss is observed concomitant with the formation of new solution species tentatively formulated as solvated oligomers. 35 refs., 4 figs., 7 tabs.« less

Effect of solvent on the reactions of coordination complexes. Part 8.—Kinetics of solvolysis of cis-(chloro)(ethanolamine)bis(ethylenediamine)cobalt(III) in methanol–water, propan-2-ol–water and t-butyl alcohol–water

The solvolysis of cis-(chloro)(ethanolamine)bis(ethylenediamine) cobalt (III) in aqueous methanol, propan-2-ol and t-butyl alcohol results in the formation of the chelated ethanolamine complex, cis-[Co(en)2(NH2CH2CH2OH)]3+. The pseudo-first-order rate constant (ksobs) of this reaction decreases with increasing mole fraction (Xorg) of the organic cosolvent, the effect being less marked with increasing hydrophobicity of the alcohols. The plots of log ksobsvs.D–1s(Ds= bulk dielectric constant) are curved. The plots of log ksobsvs. Grunwald Winstein ‘Y’ parameter are nearly linear for CH3OH–H2O and propan-2-ol-H2O, but appreciably curved t-butyl alcohol–H2O. Under isodielectric conditions (Ds= 50) at 50 °C the plot of log ksobsvs.Xorg for CH3OH–H2O, C2H5OH–H2O, (CH3)2CH—OH–H2O, (CH3)3C—OH–H2O and (CH3)2CO–H2O in water-rich media is a straight line from which the data point for ethylene glycol–H2O (XEG= 0.36) shows positive deviation indicating its better solvating ability. The observed variation of the rate constant on solvent composition (log ksobs= log kwobs– a Xorg+bX2org) for a given aquo-organic cosolvent is interpreted in terms of a preferential solvation model. The plots of activation enthalpy and entropy vsXorg exhibit maxima and minima, thereby indicating that solvent structural changes play a significant role even for this intramolecular dissociative interchange process. The solvolysis of the complex in 99 % D2O yielded a solvent isotope effect (kH2O/kD2O= 12.6) at 50 °C, which is slightly lower than the value for several other analogous alkylamine complexes.

Organoamine and organophosphate molybdenum complexes as lubricant additives

The friction and wear characteristics of molybdenum complexes, from which sulphur is absent, were examined under reciprocating sliding conditions by adding them to a paraffinic base oil with, and without, sulphur and phosphorus compounds as additives. Two kinds of molybdenum complex were used, i.e. an alkylamine complex and an alkylphosphate complex. The complexes were capable of forming MoS 2 despite the absence of sulphur in their constituents when they were added to the base oil containing sulphur compounds. The friction was reduced by the formation of a surface film comprising MoS 2 but the wear performance was little improved by combining the alkylamine complex with a sulphur compound. Both the friction and the wear performance were improved markedly by the formation of FePO 4 besides MoS 2, i.e. it was effective for the alkylamine complex and the alkylphosphate complex to be used together with sulphur and phosphorus compounds and with sulphur compounds respectively.

The role of hydrogen vibrations in the radiationless deactivation of chromium(III)-alkylamine complexes in their lowest doublet state

The role of hydrogen vibrations in the radiationless deactivation of chromium(III)-alkylamine complexes in their lowest doublet state

Anionopentaaminecobalt(III) complexes with polyamine ligands. XIV. The kinetics of aquation, mercury(II), assisted aquation and base hydrolysis of some chloro(diethylenetriamine)bis(monoamine)cobalt(III) complexes

Second order rate constants for the Hg 2+ assisted aquation of some unsym-fac-cis-CoCl(dien)(A) 2+ 2 complexes (A = NH 3, MeNH 2, EtNH 2, nPrNH 2, nBuNH 2, pentylamine, hexylamine, benzylamine, pyridine, 4-propylpyridine, 3-ethyl-4-methylpyridine and 3,5-dimethyl pyridine) have been determined spectrophotometrically over a 20 K temperature range. The benzylamine and pyridine-type complexes react about ten times more slowly than their alkylamine analogues and in the latter sequence, the reactivity generally decreases with increasing chain length. Two unsym-mer-cis- (A = NH 3, EtNH 2) and one sym-fac-cis- (A = NH 3 isomers react at rates not markedly different from their unsym-fac-cis- forms. The thermal aquation of the alkylamine complexes (1.0 M HClO 4, 343 K) is complicated by a subsequent reaction, but spectrophotometric rate data were successfully obtained for the A = NH 3 isomers. Kinetic parameters for the thermal aquation of the unsym- and sym-fac-cis-CoCl(dien)(NH 3 2+ 2 isomers are 10 7 k H(298), s −1; 19.2, 3.16: E a(kJ mol −1); 95, 107: ΔS # 298 (J K −1 mol −1); −44, −20, respectively. Similar data for the base hydrolysis of sym-fac-cis- CoCl(dien)(NH 3 2+ 2 are k OH(298), M −1 s −1; 0.70: E a; 84: Δ # 298; +26.

CIRCULAR DICHROISM OF BIS(DIMETHYLGLYOXIMATO)COBALT(III) COMPLEXES CONTAINING OPTICALLY ACTIVE AMINES

Abstract The preparations and circular dichroism (CD) spectra of a series of bis(dimethylglyoximato)cobalt(III) complexes, each containing two asymmetric unidentate amines in trans positions, are reported. Tentative spectral assignments are made for the d-d region on the basis of effective D4h molecular symmetry. In all cases the rotational strengths observed for the aromatic amine complexes are larger than those observed for the alkyl amine complexes.

ESR studies of alkylamine complexes of copper(II) imides: the CuN 42− chromophore

The ESR spectra of a number of [Cu(Im) 2(RNH 2) 2] (Im = succinimidate, phthalimidate; RNH 2 = alkylamine) complexes have been examined. The ESR data support the essentially square planar geometries proposed for the compounds on the basis of other spectroscopic data. Covalency parameters evaluated from ESR data indicate that the unpaired electron spends only roughly 80 per cent of its time on the central copper ion. Covalency parameters for various CuN 4 complexes are shown to be more indicative of geometry than the degree of metal-ligand covalency. Limitations of ESR studies of Cu(II)-doped biological systems are discussed and an explanation based on the second-order perturbation approach to chemical bonding proposed.

The Thermal Decomposition of Amine Complexes of Zinc Bis(Dimethyl-Dithiocarbamate)

Abstract It has been shown that primary alkylamine complexes of zinc bis(dimethyl-dithiocarbamate) (ZDMC) are thermally unstable. The reaction proceeds via an amine exchange reaction to yield an intermediate zinc alkyldithio-carbamate dimethyldithiocarbamate which then decomposes to give N-alkyl-N′, N′-dimethylthiourea, the dimethylammonium salt of dimethyldithio-carbamic acid, and zinc sulfide as the major products. Secondary amine complexes undergo similar initial amine exchange reactions but the new dithiocarbamates produced are stable. Tertiary amine complexes undergo neither of these reactions. These reactions can occur when zinc dithiocarbamates are used as accelerators for the vulcanization of rubber.

Substituted alkylamine complexes of copper(II) and nickel(II) imides

Thirty-six complexes of copper(II) and nickel(II) succinimide and phthalimide with variously substituted primary aliphatic amines have been prepared. Composition, colours, molar conductances, magnetic properties and i.r. spectra are consistent with square-planar structure, formulation as [ MIm 2( RNH 2) 2] ( M = Cu, Ni; Im = succinimide or phthalimide ion) and metal-imide bonding through the nitrogen atom of the imide ring. Correlations between the carbonyl stretching frequencies of the imide ring and the Taft polar substituent parameter ( σ ∗ ) show that the electronic effects of the amine substituents are transmitted to affect the electron density in the imide ring. In aqueous and chloroform solution octahedral solvent coordination occurs. The 2E g ← 2T 2g transition ( M = Cu) and the 3T 1g(P), 3T 1g(F) ← 3A 2g transitions ( M = Ni) shift to lower energies as the inductive electron releasing capacities of the amine substituents increases. This suggests that metal-nitrogen π-bonding plays an important part in determining the metal-imide bonding.

Spectrochemical Studies of the Primary Alkylamine Complexes of Nickel(II) and an Evaluation of the Donor Properties of Amines

Spectrochemical Studies of the Primary Alkylamine Complexes of Nickel(II) and an Evaluation of the Donor Properties of Amines