Structural and spectroscopic studies of some copper(I) halide tert-butyl isocyanide adducts

Single-crystal structural characterizations confirm the existence of the unusual 1 : 4 copper(I) halide : unidentate ligand adducts [Cu(CNt-Bu)4]X for X = Cl, Br (two forms), I (the chloride and one form of the bromide being solvated) with crystal packing dominated by stacks of interleaving cations. Cu-C range between 1.941(2) and 1.972(4) A. The structure of the 1 : 2 chloride complex is also recorded, being [ClCu(CNt-Bu)2], with the copper(I) atom environment trigonal planar, while CuCN : (CNt-Bu) (1 : 1) is a single-stranded polymer which spirals about a crystallographic 3-axis (CN scrambled), the ligands being pendant from the ...CuCNCuCN... string. The (5Cu static broadline NMR spectra of [Cu(CNt-Bu)4]I and [Cu(CNt-Bu)4]Br.H2O in the solid state exhibit dominant, narrow -1/2 <--> +1/2 central transition resonances and associated +/-1/2 <--> +/-3/2 satellite transition resonances which are characteristic of first-order quadrupole broadened systems, while associated high-resolution 65Cu MAS NMR data provide accurate measurement of the 65Cu isotropic chemical shifts. Both approaches provide complete data on the quadrupole and chemical shift interactions which contribute to these spectra. Far-IR spectra of products of reactions involving a range of CuX : t-BuNC ratios reveal the existence of 1 : 1.5 adducts for X = Br, I. Metal-carbon and metal-halogen bands are assigned in the far-IR spectra, which indicate a binuclear double halogen-bridged structure for the 1 : 1.5 complexes.     

Ylid complexes of organotin and -lead halides

Carbonyl-stabilised ylids form complexes of varying stoichiometries with organotin and -lead halides     

Synthesis and spectroscopic studies of some quinolylmethylphosphonates

Monoethyl esters of 2-quinolylmethylphosphonic acid ( 3 ) and 8-quinolylmethylphosphonic acid ( 6 ) have been prepared. The corresponding diethyl esters 1 and 4 , and sodium salts of monoesters 2 and 5 , respectively, have also been isolated. The properties of the monoethyl esters of 8- and 2-quinolylmethylphosphonic acid are very different. While the former was isolated as the hydrochloride, the latter did not form such a salt. Molecular weight determination indicated a dimeric structure of the monoester 3 , and spectroscopic measurements confirmed the association presumably owing to the hydrogen bonding between the P?O and P-OH groups.     

Synthesis and spectroscopic studies of phenyllead halide and thiocyanate adducts with hexamethylphosphoramide

Hexamethylphosphoramide (HMPA) adducts of the type Ph₃PbX·HMPA (X=Cl, Br, I, and NCS), Ph₂PbX₂·2HMPA (X=Cl, Br, and I), and Ph₂PbX₂·HMPA (X=Br and I), have been prepared and characterized by infrared, Raman, mass, and ³¹P nmr spectroscopy. Molecular weight and infrared solution data show that Ph₃PbX·HMPA adducts dissociate in benzene, the degree of dissociation being NCS«Cl<Br<I. The thiocyanate adducts Ph₃PbNCS·HMPA and Ph₂Pb(NCS)₂·2HMPA have v(CN) and v(CS) frequencies in the solid state, and v(CN) frequencies and absorptivities in benzene solution consistent with N-bonded thiocyanate in the solid state and in benzene solution. Vibrational frequencies are reported in the range 260 to 80 cm⁻¹ and assignments are made for v(Pb-X), v(Pb-O0, and v(Pb-NCS) modes. The 1:1 adducts Ph₃PbX·HMPA are monomeric and trigonal bipyramidal, whereas the 1:2 adducts Ph₂PbX₂·2HMPA are monomeric and cis-octahedral and the Ph₂PbX₂·HMPA appear to be halogen bridged polymers with lead six-coordinate. Coordination of HMPA causes a small upfield change in ³¹P chemnical shift values, and ²J(Pb-P) values vary with X in the order: NCS>I-Br>Cl for Ph₃PbX·HMPA adducts. Corresponding tin and lead adducts are compared with respect to mode of adduct formation.     

Preparation and spectroscopic studies of diorganotin oxycarbonates

The synthesis, ^119mSn Mössbauer and infrared spectra of a series of diorganotin oxycarbonates of the type, (R₂Sn)₂OCO₃·nH₂O, where R = Me, Et, Ph, n = 0; R = Pr, Bu, Oct, n = 1, are reported.Structures are proposed for these compounds in the solid state, on the basis of their spectroscopic data.     

FT-Raman spectroscopic studies of guarana and some extracts

The Raman spectrum of guarana, an important product of the Amazonian rain forest, has been investigated; the therapeutic properties of guarana and it's extracts have been realised for some time and have been attributed to guaranine, which could be a complex of caffeine and tannins or to a new xanthine natural product. The purpose of this study is two-fold: firstly, to provide molecular structural information about guarana seeds and their extracts and, secondly, to test the viability of using the technique as a method of verification of genuine guarana extracts from synthetic composites. Raman spectroscopy shows that the composition of the guarana is very similar for the whole seed and for the outer and inner portions of the dissected seed, which are closely similar also to the ground commercial powders produced in the Amazon for the distributors. The results indicate that Fourier-transform Raman spectroscopy could be used for the monitoring of quality control of guarana products in the phytopharmaceutical industry.     

Photoelectron spectroscopic studies of some alkoxy phenalenones

The Hel (21.22 eV) vapor phase photoelectron spectra of 1-phenalenone and its 9-substituted OH, OMe, OEt and O n-Bu derivatives have been measured. The low ionization potential regions show characteristic bands arising from π_cc and n_o orbitals and their interactions. The assignments are based on data from SPINDO calculations as well as correlations based on a composite-molecule approach. An apparent variation in intramolecular H-bonding in the OH and OMe compounds is explained in terms of Me steric interactions.     

几个石松类生物碱的质谱分析

采用电子轰击电离高分辨质谱及B/E联动扫描(LinkedScan)法,研究了HuperzineE,F,G三个lycopodine类新生物碱的质谱行为。并应用这些结果确定了另一个新生物碱HuperzineO的结构。     

IR spectroscopic studies of some uranyl tetrachloride complexes

The IR spectra of dipotassium, dirubidium and diammonium uranyl tetrachloride hydrates (K₂UO₂Cl₄·3H₂O, Rb₂UO₂Cl₄·H₂O, (NH₄)₂UO₂Cl₄·4H₂O) have been measured in the region from 4000 down to 30 cm⁻¹. A normal coordinate analysis of the (UO₂Cl₄)²⁻ ion apart from the K⁺, Rb⁺ and NH₄⁺ ions has been made using Wilson's FG matrix method. The force constants associated with the UO and UCl bonds have been obtained on the basis of both the force models of modified Urey-Bradley and valence force fields. An effort has been directed towards the understanding of the uranyl bond weakening with coordination of the ligands. It has been suggested that this bond weakening is caused by charge transfer from the ligands to the uranium atom.     

Conformation studies of some sulphurdiimides by spectroscopic techniques

¹H, ¹³C, ¹⁴N and ¹⁵N data are reported for some diphenylsulphurdiimides, as well as some electronic spectroscopic results. The ¹H NMR spectra lead to the identification of symmetric and unsymmetric forms, whose relative amounts are determined by integration at various temperatures. For the first time both forms are observed in the electronic spectra and assignments are given. True ϵ_o values are reported and the question of molecular planarity discussed.     

Vibrational spectroscopic and thermal studies of some 3-phenylpropylamine complexes

Four new Hofmann–3-phenylpropylamine (3PPA) type complexes with chemical formulae M(3PPA)₂Ni(CN)₄ (M = Ni, Co, Cd, and Pd) have been prepared and their vibrational spectra are reported in the region of 4000–60 cm⁻¹. The vibrational bands arising from 3PPA ligand molecule, the polymeric sheet and metal–ligand bands of the compounds are assigned. The thermal behaviour of these complexes is also provided using the DTA and TGA along with the magnetic susceptibility data. The results indicate that the monodentate 3PPA ligand molecule bonds to the metal atom of |M–Ni(CN)₄|_∞ polymeric layers and hence the compounds are similar in structure to Hofmann-type complexes.     

PMR and UV-vis spectroscopic studies on structure of some N-vinylcarbazoles

The PMR spectra are presented of some N-vinylcarbazoles (NVC) i.e. of 3-halogeno-NVC, 3-nitro-NVC, 3,6-dihalogeno-NVC, 3,6-dinitro-NVC, 1,3,6-trihalogeno-NVC and 1,3,6,8-tetra-halogeno-NVC. The chemical shifts show that in both tri- and tetra-substituted NVC derivatives the rotation of the vinyl group is strongly restricted. This group occupies a plane perpendicular to the carbazole ring and this conclusion is substantiated by the UV-VIS absorption spectra of selected NVC derivatives.     

Synthesis and spectroscopic studies of some fluorinated 1,3,5-triazine derivatives

Tri-substituted derivatives of 2,4,6-trichloro-1,3,5-triazine have been prepared in good yields by the reaction of 2,4,6-trichloro-1,3,5-triazine with various aromatic amines. These new types of products have been characterised by elemental analysis, IR, ¹H and ¹⁹F NMR spectral studies.     

Vibrational spectroscopic and thermal studies of some 3-phenylpropylamine complexes

Four new Hofmann–3-phenylpropylamine (3PPA) type complexes with chemical formulae M(3PPA)₂Ni(CN)₄ (M = Ni, Co, Cd, and Pd) have been prepared and their vibrational spectra are reported in the region of 4000–60 cm⁻¹. The vibrational bands arising from 3PPA ligand molecule, the polymeric sheet and metal–ligand bands of the compounds are assigned. The thermal behaviour of these complexes is also provided using the DTA and TGA along with the magnetic susceptibility data. The results indicate that the monodentate 3PPA ligand molecule bonds to the metal atom of |M–Ni(CN)₄|_∞ polymeric layers and hence the compounds are similar in structure to Hofmann-type complexes.     

Preparation and properties of some cyclic germanium 1,4-cyclohexanediolates

Colourless liquids of cyclic compounds of the type:

have been prepared by reactions of dibutylgermanium dichloride with cis-1,4-cyclohexanediol or cis,cis,cis-2,5-di-tert-butyl-l,4-cyclohexanediol, in benzene in the presence of a hydrogen halide acceptor.Under similar conditions germanium tetrachloride gave solid products of the type:

Physical and spectroscopic data (IR, Raman, and MS) are given and discussed.     

Preparation and spectroscopic studies of PbS/nanoMCM-41 nanocomposite

The present work describes the preparation and characterization of nanosized PbS particles inside the mesopore channels of nanoMCM-41 silicate molecular sieves. The encapsulation of the lead sulfide was carried out at room temperature by ion-exchange method. Diffuse reflectance ultraviolet–visible spectroscopic studies showed a significant shift in the absorption band for the entrapped metal sulfide as compared to corresponding bulk sulfide. Thus, confirming the quantum confinement of the incorporated nanoparticles in nanoMCM-41.     

Theoretical studies on vibrational spectra of some halides of group IVB elements

The vibrational spectra of group IVB elements halides MX4 (M=Ti(IV), Zr(IV), Hf(II); X=F, Cl, Br and I), have been investigated by ab initio RHF, MP2 and density functional theory B3LYP method with LanL2DZ basis sets. The optimized geometries, calculated vibrational frequencies and Far-IR intensities of MX4 are evaluated via comparison with experimental data. The vibrational frequencies, calculated by these methods, are compared to each other. The results indicate that B3LYP method is more reliable than RHF and MP2 methods for the frequencies calculations for these compounds. With this method, some vibrational frequencies of M2X6(2+)(M=Ti(IV), Zr(IV) and Hf(II); X=F, Cl, Br and I) are also predicted.     

Theoretical studies on vibrational spectra of some halides of Group IIB elements

The vibrational spectra of Group IIB elements halides MX2 and their dimers M2X4 (M=Zn(II), Cd(II) and Hg(II); X=F, Cl, Br and I) have been systematically investigated by ab initio RHF and B3LYP methods with LanL2MB, LanL2DZ and SDD basis sets. The optimized geometries, calculated vibrational frequencies are evaluated via comparison with the experimental data. The vibrational frequencies, calculated by these methods with different basis sets, are compared to each other too. The best results can be obtained by RHF/SDD method, with this method, the deviations for MX2 and Hg2X4 are <7%. Some vibrational frequencies of M2X4 that have not been experimentally reported are also predicted.     

Optishift PMR spectroscopic studies on some quinoxaline amino esters and dipeptides

Optishift pmr spectral measurements on a series of N-(2-quinoxaloyl)α-amino esters and the C₃-CH₃ analogues indicate that their L-isomers are optically pure. Such measurements also show that the Eu atom in Eu(tfc)₃ preferentially complexes with the amide carbonyl. Similar optishift pmr studies on model quinoxaline-dipeptide esters reveal that the amino-terminal α-amino acid suffers appreciable racemization during the coupling process with triphenylphosphite-pyridine, whereas no detectable racemization is observed with diphenylphosphoryl azide. A Bystrov's model is suggested for the quinoxaline-dipeptide-Eu complexes studied. The benzylic protons of phenylalanine and the isopropyl methyls in their quinoxaline derivatives show signal splitting due to diastereotopy in the presence of Eu(tfc)₃.