Synthesis of C-functionalized acetylacetone and its europium complex. Preparation and study of luminescence of europium-containing sol-gel films

New fuctionalized ligand 3-(3′-triethoxysilylpropylaminocarbonyl)pent-2-on-3-en-4-ol (EtO)₃SiCH₂·CH₂CH₂NHC(O)-C[C(O)CH₃][=C(OH)CH₃] (I) containing ketoenol and triethoxysilyl groups is synthesized from 3-triethoxysilylpropyl isocyanate (EtO)₃SiCH₂CH₂CH₂N=C=O and acetylacetone. The reaction is accompanied by the formation of 2-(3′-triethoxysilylpropylaminocarboxy)-pent-2-en-4-one (EtO)₃SiCH₂CH₂·CH₂NHC(O)-OC(CH₃)=CH-C(O)CH₃ (II), the product of addition of acetylacetone enol form to isocyanate group. The ratio of amide I and urethane II forms is 7:3. Europium(III) tris[3-(3′-triethoxysilylpropylaminocarbonyl) pent-2-on-3-en-4-olate] is prepared from I and Eu(i-OPr)₃. An alternative pathway consists in the reaction of europium tris(acetylacetonate) with 3-triethoxysilylpropyl isocyanate. Conditions of formation of transparent europium-containing sol-gel films were developed. Thermal stability and photoluminescence of the films were investigated.     

The molecular and electronic structure features of silatranes, germatranes, and their carbon analogs

Molecular geometries of fifty-six metallatranes N(CH₂CH₂Y)₃M-X and fifty-six carbon analogs HC(CH₂CH₂Y)₃M-X (M = Si, Ge; X = H, Me, OH, F; Y = CH₂, O, NH, NMe, NSiMe₃, PH, S) were optimized by the DFT method. Correlations between changes in the bond orbital populations, electron density ρ(r), electron density laplacian ∇²ρ(r), |λ₁|/λ₃ ratio, electronic energy density E(r), bond lengths, and displacement of the central atom from the plane of three equatorial substituents and the nature of substituents X and Y were studied. As the number of electronegative substituents at the central atom increases, the M←N, M-X, and M-Y bond lengths decrease, while the M←N bond strength and the electron density at critical points of the M←N, M-X, and M-Y bonds increase. An increase in electronegativity of a substituent (X or Y) is accompanied by a decrease in the ionicities of the other bonds (M-X, M-Y, and M←N) formed by the central atom (Si, Ge). A new molecular orbital diagram for bond formation is proposed, which takes into account the interaction of all five substituents at the central atom (M = Si, Ge) in atrane molecules. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 448–460, March, 2006.     

Palladium(II)-dppe-arylazoimidazole complexes: Synthesis,and spectroscopic characterization

Reaction of [Pd(dppe)Cl₂/Br₂] with AgOTf in a dichloromethane medium followed by ligand addition led to [Pd(dppe)(OSO₂CF₃)₂] and then [Pd(dppe)(RaaiR)](OSO₂CF₃)₂ [RaaiR′ = p-R-C₆H₄-N=N-C₃H₂-NN-1-R′, (1–3), abbreviated as a N,N′-chelator, where N(imidazole) and N(azo) are represented by N and N′, respectively; R = H (a), Me (b), Cl (c) and R′ = Me (1), CH₂CH₃ (2), CH₂Ph (3), OSO₂CF₃ is the triflate anion, dppe = 1,2-bis-(diphenylphosphinoethane)]. ³¹P “¹H” NMR confirmed that due to the two phosphorus atom interaction in the azoimine symmetrical environment one sharp peak was formed. The ¹H NMR spectral measurements suggest that azo-imine link with lot of phenyl protons in the aromatic region. ¹³C (¹H) NMR spectrum, ¹H, ¹H COSY and ¹H, ¹³C HMQC spectrum assign the solution structure and stereo-retentive conformation in each complex.     

Synthesis and study of the thermal stability of siliconcontaining esters of phosphorus acids. 4. Thermal rearrangement of trimethylsilylmethyl esters of phosphorus acids

NMR spectroscopy has been used to study the thermal rearrangement of siliconeopentyl esters of phosphorus acids Me₃SiCH₂OP(O)R₂ (I, R=CF₃CH₂O, PhO, t-BuCH₂O, Bu). It has been established that in all cases the products of the rearrangement are the respective silyl esters Me₂EtSiOP(O)R₂ (II). The thermal rearrangement of (Me₃SiCH₂O)₂P(O)OR (III, R'=Ph, t-BuCH₂, Me₃SiCH₂) is similar. It has been shown that electronic and steric attributes of the substituents R and R on the phosphorus atom are practically without effect on the extent of the thermal rearrangement. The presence of acidic additives, and initiators and inhibitors of radical reactions did not significantly influence the course of the rearrangement. It was concluded that this rearrangement apparently takes place as a result of heterolysis of the C-OP bond and simultaneous nucleophilic attack on the silicon atom by the phosphoryl part of the molecule.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1155–1158, May, 1991.     

Kinetics and mechanism of the reductive elimination of oxiranes from “Platinahydrins” (Platinum β-hydroxyethyl complexes)

The β-hydroxyethyl platinum(IV) derivatives with the general formula [Cl₅Pt^IV-CH₂CH(OH)R]²⁻, where R = H (1) or CH₂Cl (2), are fairly stable in aqueous solution at pH < 7. In neutral and weakly alkaline solutions, they decompose, yielding the corresponding epoxide CH₂(O)CHR and the anion. This decomposition takes place via reductive elimination caused by an intramolecular nucleophilic attack of the oxygen atom on the α-carbon atom of “platinahydrin” 1 or 2.     

Synthesis of unsymmetrical 1,2-bis(diorganochlorosilyl)ethanes

Unsymmetrical 1,2-bis(diorganylsilyl)ethanes were synthesized by two procedures. Hydrosilylation of chloro(vinyl)silanes were used to obtain compounds of the general formula ClMe₂SiCH₂CH₂SiRMeCl with different substituents (R = Et, Vin, Ph) on the silicon atom. Chlorodealkylation of 1,2-bis(trialkylsilyl)ethanes gave compounds of the general formula ClAlk₂SiCH₂CH₂SiAlk₂Cl (Alk = Me, Et, Pr). It is established that the latter reaction provides high yields only with Me-and Et-substituted compounds, whereas Pr-substituted products are formed in poor yields. The mechamism of this reaction based on quantum-chemical calculations is offered.     

The effects of auxiliary ligands on the synthesis,crystal structures and properties of three complexes with a substituted pyridazine ligand

Abstract  Three new complexes, [Co(L)₂(SCN)₂] (1), [Co₂(L)₄(μ-N₃)₂](ClO₄)₂(H₂O)_1.5 (2), and [Ni(L)₃](ClO₄)₂(CH₃OH)₂ (3), have been synthesized and structurally characterized, where L is 3-(3′,5′-dimethyl-pyrazole)-6-Cl-pyridazine. Single crystal X-ray analyses show that all three complexes crystallize in the monoclinic crystal system. In complex (1), the Co(II) atom is in a distorted octahedral environment consisting of four nitrogen atoms from two ligands and two nitrogen atoms of SCN⁻, which is further extended into a 1D chain by intermolecular hydrogen bonds. Two Co(II) atoms in complex (2) are linked by two azide anions in a μ-1,1 mode to make a binuclear structure. Without any auxiliary ligand, the Ni(II) atom in complex (3) adopts a distorted octahedral geometry involving six nitrogen atoms from three ligands. The electronic absorption spectra of the title compounds are discussed as well. The effects of auxiliary ligands on the structures and properties of the title complexes have been studied and discussed. Graphical Abstract  Three new complexes, [Co(L)₂(SCN)₂] (1), [Co₂(L)₄(μ-N₃)₂](ClO₄)(H₂O)_1.5 (2) and [Ni(L)₃](ClO₄)₂(CH₃OH)₂ (3), have been synthesized and structurally characterized, where L is 3-(3′,5′-dimethyl-pyrazole)-6-Cl-pyridazine. Complexes (1) and (3) are mononuclear compounds, which are different from the binuclear complex (2). Auxiliary ligands are the main reasons that results in the different structures of the title complexes and their different fungicidal activities. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Structural studies of seven homoisoflavonoids, six thiohomoisoflavonoids, and four structurally related compounds

¹H and ¹³C NMR chemical shifts have been determined and assigned based on PFG ¹H, ¹³C HMQC, and HMBC experiments for 3-(4′-X-benzyl)-4-chromenones (Ia, X = CN and Ib, X = NO₂), 3-(4′-X-benzyl)-4-thiochromenones (IIa, X = Cl and IIb, X = Br), (E)-3-(4′-X-benzylidene)-4-chromanones (IIIa–IIIe, X = OCH₃, CH₃, Cl, N(CH₃)₂, Br), (Z)-3-(4′-X-benzylidene)4-thiochromanones (IVa–IVd, X = Cl, Br, F, OCH₃), 2-benzyl-1,2,3,4-tetrahydro-1-naphthol (V), 2-benzyl- and (E)-2-benzylidene-1-tetralones (VI and VII), and (E)-2-benzylidene-1-benzosuberol (VIII). The crystal structures have been determined for the following seven compounds: derivatives of 4-chromanones (IIIa–IIId), 1-tetrahydronaphtol (V), and 1-tetralones (VI and VII). The molecular features and intermolecular interactions in crystal state have been discussed.     

Homolytic reactions of <Emphasis Type="Italic">N</Emphasis>-bromohexamethyldisilazane with trialkyl(phenylalkoxy) derivatives of silicon and tin

The main product of the photoinduced reaction of N-bromohexamethyldisilazane with trialkyl-(benzyloxy)derivatives of silicon and tin R₃MO(CH₂) _n Ph (R = Me, Et; M = Si, Sn; n = 1) is N,N-dibenzylidene-C-phenylmethanediamine (hydrobenzamide). For M = Si, with increase of the length of the methylene chain between the oxygen atom and the phenyl group (n = 2, 3), the similar reaction affords the product of bromination of the benzylic carbon atom R₃MO(CH₂) _n−1CHBrPh. For M = Sn, the reaction results in the formation of 2-phenyloxacycloalkanes PhCHO(CH₂) _n−1.     

Gold(III)pentafluorophenylarylazoimidazole: Synthesis and spectral (H, C, COSY, HMQC NMR) characterisation

Reaction of [Au^III(C₆F₅)₃(tht)] with RaaiR′ in dichloromethane medium leads to [Au^III(C₆F₅)₃ (RaaiR′)] [RaaiR′=p-R-C₆H₄-N=N-C₃H₂-NN-l-R′, (1-3), R = H (a), Me (b), Cl (c) and R′= Me (1), CH₂CH₃ (2), CH₂Ph (3), tht is tetrahydrothiophen]. The nine new complexes are characterised by ES/MS as well as FAB, IR and multinuclear NMR (¹H,¹³C,¹⁹F) spectroscopic studies. In addition to dimensional NMR studies as¹H,¹H COSY and¹H¹³C HMQC permit complete assignment of the complexes in the solution phase.     

Nickel(II)-dppa-arylazoimidazole complexes: Synthesis and detailed spectroscopic study

The reaction of [Ni(dppa)(Cl)₂] or [Ni(dppa)(Br)₂] with AgOTf gives [Ni(dppa)(OTf)₂], which then form [Ni(dppa)(RaaiR)](OSO₂CF₃)₂ under the action of arylazoimidazole(RaaiR) in a dichloromethane medium [RaaiR′ = p-R-C₆H₄-N=N-C₃H₂-NN-1-R′, (I–III), abbreviated as N,N′-chelating agent, where N(imidazole) and N(azo) represent N and N’, respectively; R = H (a), Me (b), Cl (c) and R′ = Me (I), CH₂CH₃ (II), CH₂Ph (III), OSO₂CF₃ is the triflate anion]. The ¹H NMR spectral measurements suggest that a bound azoimine is responsible for a number of signals of phenyl protons in the aromatic region. The molecules of the complexes contain a number of different carbon atoms which gives a number of different peaks in the ¹³C (¹H) NMR spectrum. The text was submitted by the author in English. The text was submitted by the author in English.     

Theoretical studies on the pentacoordinate silylenoid PhCH<Subscript>2</Subscript>(NH<Subscript>2</Subscript>)CH<Subscript>3</Subscript>SiLiF

The structures of pentacoordinate silylenoid PhCH₂(NH₂)CH₃SiLiF were studied by density functional theory at the B3LYP/6-31G(d) level. Three equilibrium structures, the three-membered ring (1), the p-complex (2), and the σ-complex (3) structures, were located. Their energies are in the order of 2 > 1 > 3 both in vacuum and in THF. To exploit the stability of PhCH₂(NH₂)CH₃SiLiF, the insertion reactions of 1 and PhCH₂(NH₂)CH₃Si into C–F have been investigated, respectively. The results show that the insertion of PhCH₂(NH₂)CH₃Si is more favorable. To probe the influence of amine-coordination to the stability of PhCH₂(NH₂)CH₃SiLiF, the insertion reaction of PhCH₃CH₃SiLiF was also investigated. The calculations indicate that the insertion of PhCH₃CH₃SiLiF is more favorable than that of 1. So the N atom plays an important role on the stability of silylenoid PhCH₂(NH₂)CH₃SiLiF.     

Synthesis and crystal structures of cyclopentadienyl dimolybdenum carbonyl complexes

Reactions of the fulvenes C₅H₄C(R ₁ R ₂) [(R ₁ = CH₂CH₃, R ₂ = CH₃ (1); R ₁ = R ₂ = C₂H₅ (2); R ₁, R ₂ = (CH₂)₄ (3), R ₁,R ₂ = (CH₂)₅ (4)] with Mo(CO)₆ in refluxing xylene gave the corresponding cyclopentadienyl dimolybdenum carbonyl complexes [(η⁵-C₅H₄CR₁′R₂′Mo(CO)₃]₂ [(R ₁′ = CH₂CH₃, R ₂′ = CH₃ (5); R ₁′ = R ₂′ = C₂H₅ (6); R ₁′, R ₂′ = CH(CH₂)₃ (7); R ₁′, R ₂′ = CH(CH₂)₄ (8)], which were characterized by elemental analysis, IR and ¹H NMR spectra. The molecular structures were determined by single-crystal X-ray diffraction. The results indicated the exocyclic double bond of the ligands 1 and 2 changed into a single bond and the exocyclic double bond of the ligands 3 and 4 underwent a double-bond isomerization process.     

Ruthenium(II)-arylazoimidazole-8-hydroxyquinolinate complexes: Synthesis,spectral study (H,C, COSY,HMQC-NMR) and redox properties

The reaction of [Ru(OH₂)₂(RaaiR′)₂]²⁺ (RaaiR′ = 1-alkyl-2-(arylazo)imidazole, p-R-C₆H₄-N=N-C₃H₂NN(1)-R′, R = H (1), Me (2), Cl (3); R′ = Me (a), Et (b), CH₂Ph (c)) with 8-quinolinol (HQ) in acetone solution followed by the addition of NH₄PF₆ has afforded violet coloured mixed ligand complexes of the composition [Ru(Q)(RaaiR′)₂](PF₆). The maximum molecular peak of 1b is observed at m’z 790 (50%) in the ESI mass spectrum. Ir spectra of the complexes show -C=N- and -N=N- stretching near at 1590 and 1370 cm⁻¹. The ¹H NMR spectral measurements suggest methylene, -CH₂−, in RaaiEt gives a complex AB type while in RaaiCH₂Ph it shows AB type quartets. Considering the arylazoimidazole and oxine moitie there are twenty different carbon atoms in the molecule which gives a total of twenty different peaks in the C¹³ NMR spectrum of complex 1a. In the ¹H-¹H COSY spectrum of the present complexes, absence of any off-diagonal peaks extending from δ = 14.12 and 9.55 ppm confirm their assignment of no proton on N(1) and N(3) respectively. Contour peaks in the ¹H-¹³C HMQC spectrum in the present complexes, the absence of any contours at δ = 157.12, 160.76, 155.67 ppm and 157.68–160.2 ppm assign them to the C(2), C(6), C(g) and C(h), C(i) carbon atoms respectively. The solution structure and stereoretentive transformation in each step have been established from n.m.r. results. Cyclic voltammograme show a Ru(III)/Ru(II) couple at 1.0–1.1 V versus SCE along with three successive ligand reductions.     

New route to 1,1-difluoro-5-methylquasisilatrane

A new route to 1,1-difluoro-5-methylquasisilatrane (N→Si) F₂Si(OCH₂CH₂)₂NMe is elaborated: the reaction of chlorinated methyltrifluorosilanes F₃SiCH_3−n Cln (n = 1–3) as well as trifluoro(3-chloropropyl) silane and trifluoro(propenyl)silane with N-methyl-bis(2-hydroxyethyl)amine. The reactivity of the silanes F₃SiCH_3−n Cl _n increases with the number of chlorine atoms, that is, with the electronegativity of the CH_3−n Cl _n group.     

Theoretical study of structure and properties of hexuronic acid and <Emphasis Type="SmallCaps">d</Emphasis>-glucosamine structural units of glycosaminoglycans

The Becke3LYP functional of DFT theory was used to investigate molecular structure and sodium affinity of the systems CH₃CO₂Na (1), CH₃–O–SO₃Na (2), CH₃–NH–SO₃Na (3), saccharide_1Na₂ (4), saccharide_2Na (5), saccharide_3Na₃ (6), saccharide_4Na₂ (7), and saccharide_5Na₂ (8), respectively, which are models of N- and O-sulfate glycosaminoglycans. Interaction enthalpies, entropies and Gibbs energies of the sodium-coordinated systems in the gas phase were determined with the B3LYP/6-311+G(d,p) and B3LYP/6-31+G(d) methods. The computed Gibbs energies, ΔG ^o , of model systems 1–3 are negative and span a rather broad energy interval (from −500 to −1,500 kJ mol⁻¹). Gibbs interaction energies for sodium acetate, sodium sulfate and sodium sulfamate functions of the five saccharides, systems 4–8 are always lower than those values found for the model compounds 1–3. The ionization of sodium salts of saccharides studied in gas phase is in most cases connected with considerable conformational rearrangement of the ionic species. This rearrangement causes an additional energetic stabilization of anionic species and is connected with the substantial release of entropy.     

Reactions of carbonylmetallate anions with 1-haloalkynes

The main regularities of the reactions of 1-haloalkynes RC≡CX with carbonylmetallate anions [(η⁵-C₅R′₅)(CO)₃M]⁻ (R′ = H (1–3),, M=Cr (1), M=Mo (2), or M=W (3); R′ =Me (4–6), M=Cr (4), M=Mo (5), or M=W (6) were revealed. It was established that the first stage of the reactions of anions1–6 with bromo- or iodoalkynes RC≡CX (X=Br or I) involved the transfer of the halogen atom from the sp-hybridized carbon atom to the transition metal atom to form carbonyl halides [(η⁵-C₅R′₅)(CO)₃MX. To the contrary, the reactions of anions1–6 with chloroalkynes RC≡CCl proceeded selectively as a nucleophilic substitution at the unsaturated carbon atom, the reaction rate being governed by the nucleophilicity of the carbonylmetallate anions and the electron-withdrawing ability of the R group. These reaction paths are consistent with the structures of the lowest unoccupied molecular orbitals (LUMO) in the PhC≡CX molecules (X=Cl, Br, or I) calculated by the MNDO/PM3 method. In the case of the reactions of 1-chloroheptyne-1 C1C≡CC₅H₁₁ ⁿ, anions1–3 appeared to be insufficiently nucleophilic, but these reactions can be performed as cross-coupling of the carbonylmetallate anions with chloroalkynes catalyzed by palladium complexes. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1176–1184, June, 1999.     

N-Silatranylmethyl Derivatives of Pyrrole,Indole, and Carbazole

Organosilicon derivatives of pyrrole, indole, carbazole, and 2-methylindole containing (MeO)₃SiCH₂, Et₃SiCH₂, or N(CH₂CH₂O)₃SiCH₂ group on the nitrogen atom were synthesized. Their structure and stereoelectronic parameters were studied by X-ray diffraction, ¹H, ^{1 3}C, ^{1 5}N, and ^{2 9}Si NMR, IR and UV spectroscopy, and dielcometry, as well as by quantum-chemical calculations.     

Effects of substituents and n-donors on the energies of Si←N,Si←O,and Si=C bonds in hypervalent silenes

The effect of the nature of substituents at sp²-hybridized silicon atom in the R₂Si=CH₂ (R = SiH₃, H, Me, OH, Cl, F) molecules on the structure and energy characteristics of complexes of these molecules with ammonia, trimethylamine, and tetrahydrofuran was studied by the ab initio (MP4/6-311G(d)//MP2/6-31G(d)+ZPE) method. As the electronegativity, χ, of the substituent R increases, the coordination bond energies, D(Si← N(O)), increase from 4.7 to 25.9 kcal mol⁻¹ for the complexes of R₂Si=CH₂ with NH₃, from 10.6 to 37.1 kcal mol⁻¹ for the complexes with Me₃N, and from 5.0 to 22.2 kcal mol⁻¹ for the complexes with THF. The n-donor ability changes as follows: THF ≤ NH₃ < Me₃N. The calculated barrier to hindered internal rotation about the silicon—carbon double bond was used as a measure of the Si=C π-bond energy. As χ increases, the rotational barriers decrease from 18.9 to 5.2 kcal mol⁻¹ for the complexes with NH₃ and from 16.9 to 5.7 kcal mol⁻¹ for the complexes with Me₃N. The lowering of rotational barriers occurs in parallel to the decrease in D _π(Si=C) we have established earlier for free silenes. On the average, the D _π(Si=C) energy decreases by ∼25 kcal mol⁻¹ for NH₃· R₂Si=CH₂ and Me₃N·R₂Si=CH₂. The D(Si←N) values for the R₂Si=CH₂· 2Me₃N complexes are 11.4 (R = H) and 24.3 kcal mol⁻¹ (R = F). sp²-Hybridized silicon atom can form transannular coordination bonds in 1,1-bis[N-(dimethylamino)acetimidato]silene (6). The open form (I) of molecule 6 is 35.1 and 43.5 kcal mol⁻¹ less stable than the cyclic (II, one transannular Si←N bond) and bicyclic (III, two transannular Si←N bonds) forms of this molecule, respectively. The D(Si←N) energy for structure III was estimated at 21.8 kcal mol⁻¹. Dedicated to Academician N. S. Zefirov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1952–1961, September, 2005.     

Study of allylic rearrangement in (μ-H)Os3(μ-O=CNRCH2CH=CH2)(CO)10 (R=H or CH3) clusters

The migration of the double bond in the allylcarboxamide ligands of (μ-H)Os₃(μ-O=CN RCH₂CH=CH₂) (CO)₁₀ (R=H (1) or CH₃ (2)), (μ-D)Os₃(μ-O=CNDCH₂CH=CH₂) (CO)₁₀, and (μ-H)Os₃(μ-O=CNHCD₂CH=CH₂)(CO)₁₀ clusters was studied by¹H,²H, and¹³C NMR spectroscopy. Neither μ-D nor ND groups in the deuterated complexes are directly involved in prototropic processes of allylic rearrangement. Initially, the deuterium atom of the CD₂ group migrates to the ψ-carbon atom of the allyl fragment to form the −CD=CH-CH₂D propenyl moiety, in which the deuterium and hydrogen atoms are gradually redistributed between the ψ-and β-carbon atoms. The triosmium cluster complexes containing the bridging carboxamide ligands O=CNRR' catalyze the allylic rearrangement ofN-allylacetamide. Based on the data obtained, the probable scheme of the allylic rearrangements in clusters1 and2 was proposed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2182–2186, November, 1999.