Organotin(IV) derivatives of mercaptosuccinic and thiodiacetic acids

Di- and tri-organotin(IV) complexes of general formula R₂SnAH, (R₃Sn)₂AH, R₂SnB, (R₃Sn)₂B (A=dianion of mercaptosuccinic acid; B=dianion of thiodiacetic acid; R=Me, Et, nPr, nBu, nOct in R₂Sn and nBu in R₃Sn) have been synthesized and characterized by elemental analysis, IR and ¹H and ¹³C NMR spectroscopy. These data support the preferential binding of sulphur over carboxylate by tin(IV) in R₂SnAH and (R₃Sn)₂AH. R₂SnAH complexes are assigned pentacoordinated bridged polymeric trigonal bipyramidal geometry whereas (R₃Sn)₂AH complexes are monomeric with trigonal bipyramidal geometry at tin arising from a bidentate carboxylate group at one tin atom and from weak bonding via Sn←O?C at the other tin atom. In R₂SnB and (R₃Sn)₂B, tin(IV) binds to two carboxylate groups in a unidentate and a bidentate manner respectively, resulting in tetracoordinated and pentacoordinated structures. Potential uses of these compounds are discussed.     

Temperature effects on the IR spectra of crystalliine amino acids,dipeptides, and polyamino acids. I. Glycine

The IR spectra of the α, β, and γ polymorphic modifications of pure glycine (without diluents) have been studied in the temperature range 93–433 K; changes in the IR spectra caused by variations of temperature are correlated with previously obtained diffraction data about polymorphic transitions, anisotropic compression of structure, and changes in hydrogen bond parameters.     

Electrical conductivity and IR spectra of molten benzoic acid

Impedance method was used to measure the electrical conductivity of benzoic acid melts, and the concentration of free protons in these melts was estimated. IR spectroscopic data are presented and the existence of benzoic acid in melts in the form of molecules is suggested.     

Organotin (IV) derivatives of L-cysteine and DL-penicillamine

The preparations of chlorodimethyl- and chlorodi-η-butyl tin(IV) derivative of L-cysteine, L-cysteine ethyl ester and DL-pencillamine are described. Infrared, n.m.r. and mass spectral data are presented. The compounds contain SnS bonds and suggestions for structures are made.     

New mesogens with cubic phases: hydrogen-bonded bipyridines and siloxane-containing benzoic acids I. Preparation and phase behaviour

Several 4-(oligodimethylsiloxyl)alkoxybenzoic acids and their hydrogen-bonded complexes with 4,4-dipyridyl or 1,2-bis(4-pyridyl)ethane were prepared and their phase behaviour studied by DSC and polarized optical microscopy. The neat acids showed no liquid crystalline phases. The 4,4-dipyridyl complex of 4-(n-heptamethyltrisiloxyl)hexyloxybenzoic acid (Si3C6BA) exhibits an optically isotropic, highly viscous liquid crystalline phase below a smectic A phase. The 1,2-bis(4-pyridyl)ethane complex of Si₃C₆BA also shows an optically isotropic liquid crystalline phase above its smectic C phase. Its behaviour is similar to that of the well known cubic D phase found in 4-n-alkoxy-3-nitrobiphenyl-4-carboxylic acids. In the hydrogenbonded mesogens studied herein, the cubic phase appears to assemble spontaneously in order to take account of the chemical incompatibility between the siloxane moiety terminating the H-bonded complex and the stiff aromatic cores. The transition temperatures of the cubic phases in these materials is around 100^oC, hence they are amenable to a variety of physical measurements.     

New mesogens with cubic phases: hydrogen-bonded bipyridines and siloxane-containing benzoic acids I. Preparation and phase behaviour

Several 4-(oligodimethylsiloxyl)alkoxybenzoic acids and their hydrogen-bonded complexes with 4,4-dipyridyl or 1,2-bis(4-pyridyl)ethane were prepared and their phase behaviour studied by DSC and polarized optical microscopy. The neat acids showed no liquid crystalline phases. The 4,4-dipyridyl complex of 4-(n-heptamethyltrisiloxyl)hexyloxybenzoic acid (Si3C6BA) exhibits an optically isotropic, highly viscous liquid crystalline phase below a smectic A phase. The 1,2-bis(4-pyridyl)ethane complex of Si₃C₆BA also shows an optically isotropic liquid crystalline phase above its smectic C phase. Its behaviour is similar to that of the well known cubic D phase found in 4-n-alkoxy-3-nitrobiphenyl-4-carboxylic acids. In the hydrogenbonded mesogens studied herein, the cubic phase appears to assemble spontaneously in order to take account of the chemical incompatibility between the siloxane moiety terminating the H-bonded complex and the stiff aromatic cores. The transition temperatures of the cubic phases in these materials is around 100^oC, hence they are amenable to a variety of physical measurements.     

GC-MS quantitation of benzoic and aralkyl carboxylic acids as their trimethylsilyl derivatives: In model solution I

Summary This paper describes the fragmentation patterns and the GC-MS quantitation possibilities of the trimethylsilyl derivatives of thirty-one aromatic carboxylic acids, using ion trap detection (ITD). Sixteen aralkyl carboxylic acids, including those containing a saturated aliphatic side chain {phenylacetic, 2-phenylbutyric, phenylglycolic (mandelic acid), β-phenyllactic, 3-hydroxyphenylacetic, β-phenylpyruvic and 3-(4-hydroxyphenyl)-propionic acids} and those with an unsaturated aliphatic side chain {cinnamic, 2-hydroxycinnamic (o-coumaric), 4-methoxycinnamic, 3-hydroxycinnamic (m-coumaric), 4-hydroxycinnamic (p-coumaric), 4-hydroxy-3-methoxycinnamic (ferulic acid), 3,4-dihydroxycinnamic (caffeic), and 4-dihydroxy-3,5-dimethoxycinnamic (sinapic) acids}, as well as, the fifteen hydroxy(methoxy) benzoic acids {benzoic, 2-hydroxybenzoic (salicylic), 3-hydroxybenzoic, 4-hydroxybenzoic, 3,5-dimethoxybenzoic, 3,4-dimethoxybenzoic (veratric), 2,6-dihydroxybenzoic (γ-resorcylic), 3-methoxy-4-hydroxybenzoic (vanillic), 2,5-dihydroxybenzoic (gentisic), 2,4-dihydroxybenzoic (β-resorcylic), 3,4-dihydroxybenzoic (protocatechuic), 3,5-dihydroxybenzoic (α-resorcylic), 2,4,5-trimethoxybenzoic (asaronic), 3,5-dimethoxy-4-hydroxybenzoic (syringic) and 3,4,5-trihydroxybenzoic (gallic) acids}, provided distinct fragmentation characteristics that were very useful for their identification and simultaneously quantitation. Based on 1–20 ng amounts of acids, very informative ions of high mass with considerable intensities ([M+TMS]⁺, [M+1]⁺), , ([M−CH₃]⁺) were obtained. In the case of the cinnamic acid derivatives, several odd electron fragments are formed by the loss of CO, HCHO and/or Si(CH₃)₄ molecules. In the case of benzoic acids the molecular ion proved to be abundant in three, the [M−CH₃]⁺ ion in nine cases out of fifteen. The special MacLafferty rearrangement product ([C₆H₅Si(CH₃)₂]⁺) was obtained in different yields. In addition to the TIC values, at least three, and in most cases four, selective fragment ions could be utilized for quantitation. The reproducibility of the data in the concentration range of 1–20 ng acids proved to be between 1.2 and 13.0% (R.S.D.). Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997     

Vibrational spectra of cyclopropenes. I. IR spectra of 3,3-disubstituted cyclopropenes

The IR spectra were measured and the vibrational problem was solved for a series of 3,3-disubstituted cyclopropenes [R¹: CH₃; R²: C(CH₃)₃ (I), C₆H₅ (II), CC–C(CH₃)₃ (III), CCH (IV)]. It was shown that a number of vibrations of the cyclopropene ring [symmetrical vibration of the ring, stretching and deformational (planar and out-of-plane) vibrations of the vinyl C–H bonds] are characteristic in frequency and form. On the basis of an analysis of the influence of a substituent at the C³ atom on the force field and the frequencies of the characteristic vibrations, it was concluded that the effect of conjugation of the substituent with _Walsh of the MO of the ring on the distribution of electron density in the ring plays a determining role.St. Petersberg University. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 1, pp. 112–124, January–February, 1993.     

Temperature effects on the IR spectra of crystalline amino acids,dipeptides, and polyamino acids. V. L-serylglycine

The IR spectra of L-serylglycine (H₃⁺N-CH(CH₂-OH)-CO-NH-CH₂-COO⁻), recorded at 413–93 K, have been studied, and the observed frequencies were assigned. Based on the results, we concluded that the stability of hydrogen bonds in the structure changed as a result of variation of temperature. The conclusions were compared with the results of IR spectroscopic studies of the crystals of α-glycylglycine, DL-serine, and glycine under the similar conditions.     

Organotin and tin(IV) derivatives of dimethyldithioarsinic acid

Organotin derivatives of dimethyldithioarsinic (dithocacodylic) acid have been obtained from the appropriate organotin chloride and the sodium salt of the latter. Tin(IV) chloride and NaS₂AsMe₂ · 2 H₂O yielded only two products, namely Cl₂Sn(S₂AsMe₂)₂ and Sn (S₂AsMe₂)₄, regardless of the reagent ratio. Spectroscopic characterization of the compounds (infrared and¹H NMR) provides structural information suggesting that the dimethyldithioarsinato group behaves as monodentate (or anisobidentate) ligand in Me₂Sn(S₂AsMe₂)₂, Bu₂Sn-(S₂AsMe₂)₂ and Cy₃Sn(S₂AsMe₂), as bidentate in Ph₂Sn(S₂AsMe₂)₂, Ph₃Sn(S₂AsMe₂) and Cl₂As(S₂AsMe₂)₂, whereas Sn(S₂AsMe₂)₄ contains both mono- and bidentate ligands, presumably in a six-coordinate structure.     

Organotin(IV) complexes of carboxylic acid derivatives

A comprehensive review, >100 references, on organotin(IV) complexes of the carboxylic acid derivatives are presented with special reference to their methods of synthesis, spectroscopic and structural studies and their biological activities. The structures of these complexes are discussed on the basis of IR, multinuclear (¹H-, ¹³C- and ¹¹⁹Sn-) NMR.     

Vibrational spectra,normal vibrations and infrared intensities of six isotopic benzoic acids

Isotopically consistent assignments of the i.r. and Raman bands of benzoic acid, benzoic-d₅ acid, benzoic-p-d acid and their —COOD analogues are given on the basis of a normal coordinate analysis for the vibrational modes in the crystalline state. The i.r. spectra of the six isotopic benzoic acids were simulated by using the calculated normal modes and a simple charge flux model.     

Organotin biocides: VII . Tri- and diorganotin derivatives of piperazine bis(dithiocarbamic) acid

Eight tri- and diorganotin derivatives of piperazine bis (dithiocarbamic) acid (H₂pdtc) of formulae (R₃Sn)₂pdtc (R = Me, Bu, Ph, cyclo-C₆H₁₁) and R₂Snpdtc (R = Me, Bu, Oct, Ph) have been synthesised, along with (ClBu₂Sn)₂pdtc, a by-product in the synthesis of Bu₂Snpdtc. On the basis of spectroscopic data, compounds of type (R₃Sn)₂pdtc are judged to be monomeric, with the tin atoms in a tetrahedral environment distorted towards five-coordinate cis-S₂SnR₃ each by a weakly bidentate CS₂ group. The diorganotin derivatives are polymeric, with a distorted trans-R₂SnS₄ geometry about the metal. Variable temperature Mössbauer spectroscopic data are presented for (Me₃Sn)₂pdtc and Me₂Snpdtc.     

Temperature effects on the IR spectra of crystalline amino acids,dipeptides, and polyamino acids. II. L-and DL-serines

The IR spectra of L-and DL-serines H ₃ ⁺ -CH(CH₂OH)-COO^? (without diluents) were investigated in the temperature range 93–413 K; the changes in the IR spectra due to temperature variations were correlated with previously obtained diffraction data on anisotropic compression of structure and changes in the geometrical parameters of the hydrogen bonds.     

Synthesis and modification of fillers with derivatives of benzoic acids

The subject of this research work was an effect of liquid crystals on the properties of filled elastomer systems. Both commercially available and own synthesized liquid crystals were used. The elastomer was ethylene-propylene rubber, while precipitated silica and calcium carbonate were used as fillers. The liquid crystals were deposited on the surface of the fillers from solution. Their effect on the mechanical properties of the vulcanizates was studied.     

Synthesis and IR spectra of some 2-aminobenzoxazole derivatives

A large number of 5-nitro-, 6-nitro-, 5-chloro-, and 6-bromo-2-aminobenzoxazoles were synthesized by the reaction of benzoxazoline-2-thiones with various amines. It was shown by IR spectroscopy that all of the compounds exist in the amino form in solution, whereas the 5-substituted compounds exist in the imino form in the solid state, and the 6-substituted compounds exist simultaneously in the two forms.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 604–607, May, 1981.The authors thank T. Dukhova, P. Braikov, I. Nachev, and T. Georgieva for their assistance in carrying out several of the experiments.     

IR spectra and structure of 4-thiobarbituric acid derivatives

On the basis of data from the IR spectra of 4-thiobarbituric acid derivatives, and their deutero analogs, and similarly constructed model compounds, it was established that the investigated substances exist in the thione lactam form and form two types of associates through intermolecular hydrogen bonds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1416–1419, October, 1977.