Heteroorganic betaines

The [Ph₃P⁺−CMe₂−SiMe₂−SEt]Br⁻ salt was prepared by the reaction of betaine Ph₃P⁺−CMe₂SiMeR−S⁻ (1a: R=Me) with EtBr. Acetylation of betaine1a or Et₃P⁺−CHMeSiMe₂−S⁻ (2a) afforded 2,2,6-trimethyl-1,3-dioxa-2-silacyclohex-5-ene-4-thione      

Heteroorganic betaines

A method for the synthesis of a new class of betaines,viz., R₃ ¹P⁺CR²R³SiR⁴R⁵S⁻, was developed. The experimental evidence for the intermediate formation of betaines R₃ ¹P⁺−CR²R³−CR⁴R⁵−S⁻ in the Wittig reaction for a series of thiocarbonyl compounds was obtained. A comparative analysis of the NMR spectra of betaines containing the⁺P−C−Si−S⁻ and⁺P−C−C−S⁻ fragments was performed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 922–930, May, 2000.     

Reaction of Ru3(CO)12 with 1,3-diferrocenylprop-2-ene-1-one. Crystal and molecular structures of the complexes Ru3(CO)8(FcC=CHCOFc)2 and [Ru(CO)2Cl(FcC=CHCOFc)]2

The reaction of Ru₃(CO)₁₂ with 1,3-diferrocenylprop-2-en-1-one,trans-FcCH=CHCOFc (where Fc is ferrocenyl), in boiling hexane afforded the complex (2c), which was converted into (3c) upon further heating. These complexes gave the complex (4) containing two Cl-bridged oxaruthenacycles upon dissolution in CHCl₃ or CH₂Cl₂. The structures of complexes 3 and 4 were established by X-ray diffraction analysis. According to the data of¹H NMR spectroscopy, the Cl-bridged complex exists in solutions as a mixture of isomers along with the monomeric form resulting from the cleavage of the halide bridges. All interconversions of the isomers occur with the participation of the monomeric form. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1616–1623, September, 2000.     

UV photolysis of protonated ruthenium and osmium decamethylmetallocenes as a new method for synthesis of the metallonium cations

Decamethylmetallocenes Cp^* ₂M (M=Ru, Os) in the presence, of acids (CF₃CO₂H, CF₃SO₃H) give thepprotonation products [Cp^* ₂MH]⁺An⁻. Broad-band UV photolysis of their solutions results in the formation of the salts of onium cations . A preparative procedure for the synthesis of these salts has been developed. Hydrolysis of the salts gives the carbinol Cp^*MC₅Me₄CH₂OH. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 587–591. March, 1999.     

Synthesis,structures and properties ofN-(trihalogermylmethyl)-substituted amides,lactams and imides,the derivatives of the five-coordinate germanium

The formation of trichlorogermyl-substituted amides, lactams, and imides occurs when 2Et₂O·HGeCl₃ is condensed with compounds possessing the -NCH₂Cl fragment and equally well when HGeCl₃ interacts with compounds containing -NCH₂OH and-NCH₂OSiMe₃ groups. In some cases, the use of the latter is more advantageous from the preparative point of view. In compounds thus obtained, the germanium is five-coordinate due to the coordination . Deceased August 13, 1993. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1793–1799, October, 1993.     

FeCl3 solutions in isopropanol-water

Summary This paper is devoted to the characterization of FeCl₃ solutions in isopropanol containing water. For this goal optical absorption and e.p.r. techniques have been used in conjunction with magnetization and M?ssbauer data reported very recently. It is shown that in a 10⁻² M solution of FeCl₃ containing 0.4 M of water the main iron(III) species present in the solution are [FeCl₄]⁻ (55%) and [FeCl₂(H₂O)₄]⁺ (20%) while the remainding 25% is due to dihydroxo dimers, . When the water concentration increases the [FeCl₄]⁻ anions are progressively destroyed, the main iron(III) species present in the solution being the dihydroxodimers and [FeCl₂(H₂O)₄]⁺. The variation of the concentration of the three species mentioned with the water content and FeCl₃ concentration is presented in this paper.     

Heteroorganic betaines

The structures of three silicon-containing organophosphorus betaines containing the⁺P−C−Si−S⁻ fragment were established by X-ray diffraction study. Due to the attractive electrostatic interaction between the anionic and cationic centers, the main chain adopts agauche conformation, whereas this chain in theS-ethyl derivative of the phosphonic salt [Ph₃P⁺−CMe₂−SiMe₂SEt]Br⁻ adopts atrans conformation. The changes in the geometric parameters of betaines depending on the substituents at the phosphorus, carbon, and silicon atoms were analyzed. The P−S bond can in principle be formed, resulting in the closure of the four-membered ring provided that additional steric hindrances at the silicon atom occur.     

Ab initio study of the structure,force field,and vibrational spectrum of the LiClO3 molecule

The geometrical structure and the vibrational spectrum of the LiClO₃ molecule are studied by the Hartree-Fock-Roothaan (HF) and configurational interaction (CI) methods taking into account single and double excitations and Davidson's correction for quadruple excitations. Double-zeta basis sets of Huzinaga-Dunning and McLean-Chandler complemented with polarization and diffuse functions are used. Potential surface sections corresponding to migration of the Li⁺ cation around the ClO ₃ ⁻ fragment are investigated. It was found that the LiClO₃ molecule has a single stable configuration of C_s symmetry with the bidentate coordination of the Li⁺ cation by the ClO ₃ ⁻ anion. The cyclic fragment is nonplanar (the dihedral angle θ(LiO₂Cl)=173°). The tridentate configuration of C_3v symmetry lies higher than the equilibrium configuration by 24.5 (HF) or 18.3 (CI) kJ/mole and is not an isomer. The ab initio force field of the molecule was refined by the scaling method. Some assignments of the IR bands of the matrix-isolated molecular forms existing in vapor over lithium chlorate are corrected. The vibration frequencies (cm⁻¹) and IR intensities (km/mole; in parentheses) are calculated with the refined force field: A′ type 1099(236), 856(81), 630(73), 557(119), 481(87), 156(66); A″ type 887(229), 459(35), 367(23). Ivanovo State Chemical Technological Academy. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 3, pp. 440–449, May–June, 1996.     

Heteroorganic betaines. 8. Synthesis and structures of silicon- and germanium-containing organoarsenic betaines R13As+—CR2R3—EMe2—S– (E = Si,Ge)

The reactions of ylides R¹ ₃As=CHR² with hexamethyl-2,4,6-trisila- and hexamethyl-2,4,6-trigermatrithiacyclohexanes afforded betaines R¹ ₃As⁺—CHR²—SiMe₂—S^– (2) (R¹ = Et; R² = Ph (a), Me₃Si (b); R¹ = R² = Ph (c)) and Et₃As⁺—CH(SiMe₃)—GeMe₂—S^– (3), respectively. Betaines 2a,b and 3 were characterized by multinuclear NMR spectroscopy. According to the X-ray diffraction data, in the crystals the As⁺—C—E—S^– main chain (E = Si or Ge) of molecules 2a,b and 3 adopts a twisted cis conformation due to strong intramolecular Coulomb interactions between the anionic and cationic centers. The equilibrium geometries of isolated molecules 2a and 3, which were calculated within the framework of the density functional theory (the PBE functional, the TZ2P basis set), are in qualitative agreement with the X-ray data. In solutions, betaines 2a (in the absence of Li salts) and 2c (in the presence of LiBr) selectively decomposed according to the Corey—Chaykovsky reaction, which was accompanied by elimination of R₃As and, probably, the intermediate formation of silathiirane. The subsequent transformation of the latter afforded 2,2,4,4-tetramethyl-5-phenyl-2,4-disila-1,3-dithiolane.     

Potentiometric study of the formation of hydroxo complexes of [Cu(terpy)]2+. Synthesis and crystal structure of [Cu(terpy) (H2O)](CF3SO3)2

Two complexes of formula [Cu(terpy)(H₂O)](CF₃SO₃)₂ (1) and [Cu(terpy)(OH)]BPh₄ (2) (terpy=2,2′∶6′,2″-terpyridine and BPh₄=tetraphenylborate anion) have been synthesized and characterized by spectroscopic techniques. The x-ray crystal structure of (1) has been determined by x-ray diffraction. The structure is made up of [Cu(terpy)(H₂O)]²⁺ mononuclear cations plus semi-coordinated CF₃SO₃ ⁻ anions. The coordination geometry around the copper atom is approximately elongated tetragonal octahedral. The oxygen atom of water and the three nitrogen atoms of terpy occupy the equatorial sites whereas the apical ones are filled by trifluoromethanesulphonate oxygen atoms. The formation of hydroxo complexes of [Cu(terpy)(H₂O)]²⁺ has been investigated by potentiometry in aqueous solutions and the constants of the Equilibria (1) and (2)      

Ab initio study of the complexes of first-row transition-metal ions with CH, CH2, and CH3

The geometries and bonding characteristics of the complexes of the first-row transition-metal ions with CH, CH₂ and CH₃ were investigated byab initio molecular orbital theory. MCH⁺ and MCH₂ ⁺ are linear and coplanar, respectively. Both of them are with obvious treble or double bond characteristics, but these multiple bonds are mostly “imperfect”. The calculated bond dissociation energies of , and are mostly close to the experimental values, and appear in similar periodic trends from Sc to Zn. Project supported by the National Natural Science Foundation of China (Grant No. 29170070).     

Synthesis and structure of the platinum complexes [Bu4N]+[PtBr5(DMSO)]?, [Ph4P]+[PtBr5(DMSO)]?, and [Ph3(n-Am)P]+[PtBr5(DMSO)]?

The complexes [Bu₄N]₂⁺[PtBr₆]²⁻ (I), [Ph₄P]₂⁺[PtBr₆]²⁻ (II), and [Ph₃(n-Am)P]₂⁺ (III) are synthesized by the reactions of tetrabutylammonium bromide, tetraphenylphosphonium bromide, and triphenyl(n-amyl)-tetraphenylphosphonium bromide, respectively, with potassium hexabromoplatinate (mole ratio 2: 1). After recrystallization from dimethyl sulfoxide, complexes I, II, and III transform into [Bu₄N]⁺[PtBr₅(DMSO)]⁻ (IV), [Ph₄P]⁺[PtBr₅(DMSO)]⁻ (V), and [Ph₃(n-Am)P]⁺[PtBr₅(DMSO)]⁻ (VI). According to the X-ray diffraction data, the cations of complexes IV–VI have a slightly distorted tetrahedral structure. The N-C and P-C bond lengths are 1.492(7)–1.533(6) and 1.782(10)–1.805(10) ?, respectively. The platinum atoms in the mononuclear anions are hexacoordinated. The dimethyl sulfoxide ligands are coordinated with the Pt atom through the sulfur atom (Pt-S 2.3280(18)–2.3389(11) ?). The Pt-Br bond lengths are 2.4330(6)–2.4724(6) ?.     

A new type of polarographic catalytic wave of organic compound

The polamgraphic behavior and catalytic wave mechanism of medroprogestemne acetate (MPA) were studied in both aqueous and DMF media. In 0.2 mol/L acetic acid-sodium acetate (pH 5.0) buffer solution, the bond of MPA first undergoes le, lH⁺ reduction to form protonated free radical HMPA, the further reduction of HMPA in le,1H⁺ process is simultaneous with the dimerization reaction between HMPA and neutral molecular MPA. In DMF media containing 0.1 mol/L tetrabutylammonium tetrafluoborate (TBA.BF₄), the bond of MPA shows two le, 1H⁺reduction waves, which are ascribed to the reduction of MPA and free radical MPA.^-, respectively. Here, no dimerization reaction occurs. These processes produce the reduction wave of MPA. In the presence of oxidant KIO₃,a polamgraphic catalytic wave of MPA is observable due to a chemical reaction between HMPA. or MPA.^- and KIO₃ as well as its intermediate species to regenerate MPA. The catalytic wave, which is caused by the reduction of organic compound itself and the chemical reaction between oxidant and organic intermediate free radical to regenerate original organic compound, is a new-type wave of organic compound. Under optimum experimental conditions, the sensitivity of MPA catalytic wave in the presence of KIO₃ is an order of magnitude higher than that of its reduction wave. The catalytic wave can be used for analytical purpose. The calculated rate constant of catalytic reaction is 1.7 × 10³ mol·L^-1·s^-1. Project supported by the National Natural Science Foundation of China (Grant No. 29875017).     

Darstellung und Charakterisierung von Halogeno(diethyldithiocarbamato) (triethyl- und triphenylphosphin)palladium(II)-Komplexen

The Complexes [Pd(PEt ₃)₂ dtc]X (1) and Pd(PR ₃)Xdtc (2, 3) (dtc=S₂CNEt ₃;X=Cl, Br, I;R=Et, Ph) have been prepared. Conductivity, susceptibility, UV and IR measurements show that the cations [Pd(PEt ₃)₂ dtc]⁺ of1 and the complexes2, 3 have square-planar structure.

     

IR spectroscopic investigation of the structure of polymeric uranyl di(2-ethylhexyl)phosphate molecules in C6H6 and CCl4 solutions

Using IR spectroscopy, we studied the types of coordination of POO groups in di(2-ethylthexyl)phosphate anionx X⁻ with UO ₂ ²⁺ cations in the C₆H₆ and CCl₄ solutions of the polymer molecules (UO₂X₂)_p. The polymers exhibit tridentate-bridge coordination (I), which is not typical of (MX_n)_p salts where the phosphoryl oxygen atom forms two bonds with U(VI) atoms. When a few U(VI) atoms (≳7%) interact with donar additives, all POO group I change their coordination to the usual bidentate-bridge type, , resulting in a structural transformation of the polymer. The bridging POO group are responsible for the difference in the dimerization and trimerization constants and the constants of the subsequent addition of the monomer molecules UO₂X₂ to the polymer chain (UO₂X₂)_p. It is suggested that type I coordination of X⁻ to U(VI) is due to an extended bond between the 2p²-electrons of the phosphoryl oxygen atom of the X⁻ anion and a vacant f-orbital of the U(VI) atom (p_π−f_π interaction). This unusual type of bond between uranium (VI) and tributyl phosphate (TBP) phosphoryl oxygen was found earlier for the UO₂Cl₂·2TBP complex. Institute of Catalysis, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturmoi Khimii, Vol. 35, No. 6, pp. 60–65, November–December, 1994. Translated by K. Shaposhnikova     

Aluminum complexes with mono-and dianionic diimine ligands

The metathesis reaction of the magnesium complex [(dpp-BIAN)²⁻Mg²⁺(THF)₃] (dpp-BIAN is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) with one equivalent of AlCl₃ in toluene gave the [(dpp-BIAN)²⁻AlCl₂]⁻[Mg₂Cl₃(THF)₆]⁺ complex (1). Reduction of dpp-BIAN with aluminum metal in the presence of AlCl₃ and AlI₃ in toluene and diethyl ether afforded the radical-anionic complex [(dpp-BIAN)⁻AlCl²] (2) and the dianionic complexes [(dpp-BIAN)²⁻AlI(Et₂O)] (3) and [(dpp-BIAN)²⁻AlCl(Et₂O)] (4), respectively. Compounds 1–4 were isolated in the crystalline state and characterized by IR spectroscopy and elemental analysis. The structures of compounds 1–3 were established by X-ray diffraction. Compound 2 was characterized by ESR spectroscopy. Compounds 3 and 4 were studied by 1H and 13C NMR spectroscopy. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 409–415, March, 2006.     

Heteroorganic betaines. 6. Structure and reactivity of silicon-containing organophosphorus betaines with the –S—Si—C—P+ fragment: a DFT study

The structures of silicon-containing organophosphorus betaines ^–S—SiR¹ ₂—CR² ₂—P⁺R³ ₃ and their ylide isomers were calculated using the density functional approach with the gradient-corrected PBE functional and extended TZ2P basis set. Three possible pathways of thermal decomposition of these betaines were analyzed. These are (i) cleavage of the central C—Si bond with the formation of a Wittig ylide and silanethione, (ii) intramolecular nucleophilic S _N-substitution with elimination of phosphine PR³ ₃ and the formation of silathiirane (the Corey—Chaikovscky transformation), and (iii) a Wittig-type decomposition followed by the formation of substituted silaethylene.The structures of products and transition states of these reactions were calculated. The cis-gauche conformation of the ^–S—Si—C—P⁺ fragment of betaines was found to be the most stable. This is in agreement with the results of X-ray diffraction study and can be rationalized by strong Coulomb attraction between the cationic and anionic centers. The betaines are stable toward retro-Wittig thermal decomposition. The Corey—Chaikovscky formation of thiirane is preferable under conditions of thermal decomposition. Retro-Wittig-type decomposition of betaines followed by the formation of silanethione is favored by intra- and intermolecular coordination of donor ligands.     

A new method for generating organosilanones

A new method for the generation of organosilanones by the reaction of betaines, R₃P⁺-CR¹R²-SiR³R⁴-S^–, with (Et₃Sn)₂O was suggested.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2246–2247, December, 1994.This study was financially supported by the Russian Foundation for Basic Research, Project No. 94-03-09710.     

Syntheses and characterizations of cluster compounds with MoFe3Se4 cubane-like core

The reaction system of [Et₄N]₂MoSe₄, FeCI₂ and R₂NCS₂Na in DMF-CH₃CN at ambient temperature yielded the Mo-Fe-Se cluster compounds MoFe₃Se₄(μ−R₂NCS₂)₂(R₂NCS₂)₄ (R₂=Me₂(1), Et₂(2), C₄H₈(3)) with MoFe₃Se₄ core. X-ray diffraction analyses of2 revealed that the molecular structure contains a distorted cubane like M₄Se₄ core with two bridged and four chelated Et₂NCS₂⁻ ligands. The cyclic voltammetric studies of the compounds showed the reversible multielectron-transfer sequence.     

Synthesis of New Hybrid Organic-Inorganic Alumina Gels by the Sol-Gel Method

New hybrid organic-inorganic alumina gels have been prepared by reacting aluminum sec-butoxide and propane-1,2-diol, in CCl₄ as solvent. This reaction occurred without water addition and without the use of any catalyst, leading to the formation of transparent and monolithic gels. IR,²⁷Al and¹³CNMR show that an interchange reaction between OBu ^s alkoxide groups and diol groups occurred, leading to the hybrid gels. Samples heat treated at different temperatures under argon are weakly porous and have a small specific surface area. XRD indicates the presence of pure α-alumina at 1450°C.