Synthesis and structure of 5,6,7,12-tetrahydrodibenz[c,f][1,5]azabismocines

Hypervalent organobismuth compounds, 6-tert-butyl-5,6,7,12-tetrahydrodibenz[c,f][1,5]azabismocines, with 13 different substituents on the bismuth atom including halogens, alkyl, alkenyl, alkynyl, aryl, or phenylthio groups have been synthesized. A key compound, 12-chloro-6-tert-butyl-5,6,7,12-tetrahydrodibenz[c,f][1,5]azabismocine, which is a precursor for other azabismocines, has been synthesized by two different procedures; one is based on Akiba’s method using 2-bromobenzylbromide as one of the starting materials and the other is a newly developed one using a cheaper starting material, 2-chlorobenzyl chloride. The structures of 12 new bismuth compounds were determined by X-ray diffraction. The eight-membered tetrahydroazabismocine ring has proved to be highly flexible and the hypervalent Bi-N bond distances vary ranging from 2.568(3) to 2.896(5) Å, depending on the electronic nature of the substituents on the bismuth atom. The Bi-N bond distances have good linear relationship against Hammett’s σ_m constants.     

Effective synthesis and X-ray investigation of (±)-2<Emphasis Type="Italic">S</Emphasis>-2-(2-chlorophenyl)-3-acetyl-1,3-oxazolidine

The crystal and molecular structure of (±)-2S-2-(2-chlorophenyl)-3-acetyl-1,3-oxazolidine was determined by X-ray diffraction analysis. Orthorhombic crystal with unit cell parameters a = 6.7419(8) Å, b = 10.3797(12) Å, c = 14.9233(18) Å; space group P2₁2₁2₁, Z = 4, ρ _calc = 1.436 g/cm³, composition C₁₁H₁₂ClNO₂. The deviation of the chlorine atom from the mean square plane of the phenyl cycle is ?0.010(5) Å. The five-membered oxazolidine cycle has an envelope conformation, which is typical for this class of compounds; the cycle is rotated at the C-C bond with respect to the phenyl fragment (the dihedral angle is 79.7(1)°). The spatial structure of the C2 chiral center lying in the plane of the 2-chlorophenyl fragment may be described as a distorted tetrahedron with an S configuration of the sp ³ hybridized carbon atom. Analysis of torsion angles and deviation of the nitrogen atom from the surrounding three-angle plane by ?0.017(3) Å allows one to speak about a tendency toward a pyramidal structure for the trisubstituted nitrogen atom. The 3D crystal structure is formed by intermolecular hydrogen bonds of C-H...O type and a strong intermolecular contact of 3.164(3) Å between the chlorine atom and the carbonyl oxygen of the acyl group.     

Structure and dynamics of eight-membered <Emphasis Type="Italic">P,N</Emphasis>-heterocycles in solution

Conformational analysis of eight-membered P,N-heterocycles (P₂^NR₂^R') in the solution has been performed by means of NMR spectroscopy and quantum chemical calculations. The equilibrium of the С₂-symmetrical (crown, major) and С_s-symmetrical (chair-boat, minor) forms of the compounds has been revealed, the transition barriers being of about 12 kcal/mol. The presence of an aromatic substituent at the nitrogen atom significantly shifts the equilibrium towards the dominating form.     

THE PREPARATION AND CHARACTERIZATION OF Cd(XCN)4M TYPE COMPOUNDS

Abstract

A series of compounds of the type Cd(XCN)₄M (X=S and Se; M=Mn, Fe, Co and Zn) have been prepared and characterized. These compounds crystallize in the tetragonal system: space group I4[sbnd]S₄ ². The bidentate thiocynate and selenocyanate ligands coordinate to the “hard” M(II) ions through the nitrogen atom and the “soft” Cd(II) ion through the sulfur or selenium atom. The Cd[sbnd]Se bond in Cd(XCN)₄ M is slightly stronger than the Cd[sbnd]S bond while the M[sbnd]NCSe bond is slightly weaker than the M[sbnd]NCS bond. The M(II) ions tetrahedrally coordinated by the nitrogen end of XCN^? are in the high spin state. The [sbnd]NCS and [sbnd]NCSe ligands are located at about the same place in the spectrochemical series.     

Styrene polymerization with novel anilido-imino nickel complexes/MAO catalytic system: Catalytic behavior, microstructure of polystyrene and polymerization mechanism

The polymerization of styrene with novel catalytic systems of anilido-imino nickel complexes (Ar¹N = CHC₆H₄NAr²) NiBr (Ar¹ = Ar² = 2,6-dimethylphenyl, 1; Ar¹ = 2,6-dimethylphenyl, Ar² = 2,6-diisopropylphenyl, 2; Ar¹ = Ar² = 2,6-diisopropylphenyl, 3; Ar¹ = 2,6-diisopropylphenyl, Ar² = 2,6-dimethylphenyl, 4) activated by methylaluminoxane was investigated. The influence of reaction parameters (temperature, Al/Ni mole ratio, and polymerization time) on styrene polymerization was evaluated. The influence of the bulkiness of the substituents on polymerization activity and polymer characteristics was also ascertained. The obtained polystyrene was an iso-rich atactic polymer and its weight-average molecular weight reached 70 500. NMR analysis of the end groups further confirmed that styrene polymerization catalyzed by anilido-imino nickel complexes/MAO systems proceeded through a coordination mechanism, and the chain was initiated through styrene secondary insertion into the NiH and terminated mainly through β-H elimination of styrene producing the chain-end group (CHCHPh).     

A study of the transfer of the electronic influence of substituents in o-carboranes by nuclear quadrupole resonance

The ³⁵Cl NQR spectra of 2-substituted 1-chloromethyl-o-carboranes and of 1-chloromethyl-9,12-dihalogeno-o-carboranes have been investigated. The anomalous influence of two halogen atoms present in positions 9 and 12 of the carborane nucleus on the electron density of the chlorine atom in the CH₂Cl group is explained by the combined action of their –I and +M effects, and also by the effect of p d conjugation. The comparatively high ³⁵Cl NQR frequency for o-ClCH₂CB₁₀H₁₀CH is due to the large –I effect of the carboranyl group. The induction constants of a number of groups attached to the carborane ring have been evaluated. In the molecules of the 2-substituted 1-chloromethyl-o-carboranes spatial interaction between X and Cl clearly appears. The substituents X in compounds of this series can be divided into three types according to their electronic influence: 1) electron-donating substituents, 2) substituents containing a mobile hydrogen atom (capable of forming a hydrogen bond), and 3) substituents possessing an unshared pair of electrons capable of passing into the vacant 3d orbital of a chlorine atom.     

Synthesis of 4-aryl-6-indolylpyridine-3-carbonitriles and evaluation of their antiproliferative activity

A novel class of 6-indolypyridine-3-carbonitrile derivatives were synthesized and evaluated for antiproliferative activities to establish structure–activity relationship. The synthesis was carried out through one-pot multicomponent reaction of 3-acetylindole, aromatic aldehydes, ethyl cyanoacetate, and ammonium acetate in the presence of piperidine as a catalyst, using a microwave irradiation method or a traditional thermal method. This was followed by chlorination for compounds 13a–e and subsequent nucleophilic substitution of the chlorine group by ethylenediamine at C₂ position of the pyridine ring. The antiproliferative activity of these new nicotinonitriles was evaluated against human ovarian adenocarcinoma (SK-OV-3), breast adenocarcinoma (MCF-7), and cervix adenocarcinoma (HeLa) cells. Among all compounds, 2-((2-aminoethyl)amino)-4-aryl-6-indolylnicotinonitriles series (15a, 15b, 15d, and 15e) exhibited higher antiproliferative activity on the three cancer cell lines with IC₅₀ values of 4.1–13.4 μM.     

Complexation between N-allylmorpholinium derivatives and copper(I) halides. Synthesis and crystal structure of π-complex {[C4H8ONH(C3H5)]+}2[Cu2Cl4]2?

Copper(I) -complex {[C₄H₈ONH(C₃H₅)]⁺}₂[Cu₂Cl₄]^2– (I) was obtained by ac electrochemical synthesis from N-allylmorpholine hydrochloride and copper(II) chloride in ethanol and structurally characterized. In structure I, copper and chlorine atoms form unique noncentrosymmetric Cu₂Cl ₄ ^2– fragments. Both crystallographically independent N-allylmorpholinium cations are involved in the -interaction and are coordinated by the copper atom through the C=C bond of the allyl group. The trigonal pyramidal environment of the Cu(1) atom is composed of three chlorine atoms and the C=C bond, while the Cu(2) atom coordinates two chlorine atoms and the C=C bond forming a planar triangle. The extremely strong N-CCl hydrogen bond (HCl 2.2 ) prevents the Cl(1) atom from acting as a bridge and favors the formation of fragments Cu₂Cl ₄ ^2– .__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 4, 2005, pp. 306–310.Original Russian Text Copyright © 2005 by Goreshnik, Davydov, Myskiv.     

Synthesis, Raman, X-ray diffraction, and density functional studies of antimony(III) heterotetracycles displaying intramolecular transannular interactions O → Sb

A set of compounds of general formula [{S(C₆H₃S)₂O}SbHal] [Hal = Cl (1), Br (2), I (3)] has been synthesized and studied by Raman and NMR spectroscopy as well as quantum chemical DFT calculations. X-ray diffraction studies of compound 2 revealed that the oxygen atom participates as donor and the antimony atom plays the role of acceptor, adopting a Ψ-distorted trigonal bi-pyramidal geometry, where the eight-membered central ring displays a boat–boat conformation. Furthermore, a series of DFT calculations was performed on compounds 1–3 as well as calculations on the non-synthesized heterotetracyclic systems [{S(C₆H₃S)₂O}SbF] (4a) and the cation [{S(C₆H₃S)₂O}Sb]⁺ (5a). The theoretic study at DFT level indicates as the electronegativity increases at exocyclic substituent along the set of compounds, the interaction is stronger. Moreover, the topological analysis of electronic density showed the existence of critical points along the O → Sb direction which prompted us to suggest the existence of a dative bond.     

Synthesis and reactivity of neodymium(III) amido-tethered N-heterocyclic carbene complexes

The reaction of the heteroleptic Nd(III) iodide, [Nd(L′)(N″)(μ-I)] with the potassium salts of primary aryl amides [KN(H)Ar′] or [KN(H)Ar^*] affords heteroleptic, structurally characterised, low-coordinate neodymium amides [Nd(L′)(N″)(N(H)Ar′)] and [Nd(L′)(N″)(N(H)Ar^*)] cleanly (L′ = t-BuNCH₂CH₂[C{NC(SiMe₃)CHNt-Bu}], N″ = N(SiMe₃)₂, Ar′ = 2,6-Dipp₂C₆H₃, Dipp = 2,6-Prⁱ₂C₆H₃, Ar^* = 2,6-(2,4,6-Prⁱ₃C₆H₂)₂C₆H₃). The potassium terphenyl primary amide [KN(H)Ar^*] is readily prepared and isolated, and structurally characterised. Treatment of these primary amide-containing compounds with alkali metal alkyl salts results in ligand exchange to give alkali metal primary amides and intractable heteroleptic Nd(III) alkyl compounds of the form [Nd(L′)(N″)(R)] (R = CH₂SiMe₃, Me). Attempted deprotonation of the Nd-bound primary amide in [Nd(L′)(N″)(N(H)Ar^*)] with the less nucleophilic phosphazene superbase Bu^tNP{NP(NMe₂)₃}₃ resulted in indiscriminate deprotonations of peripheral ligand CH groups.     

Nitrogen-containing analogues of boron difluoride benzoylacetonate: synthesis,structure, luminescence,and quantum chemical modeling

Nitrogen-containing analogues of boron difluoride benzoylacetonate (1), i.e., boron difluoride ketoiminates (boron difluoride 3-amino-1-phenyl-2-buten-1-onate (2) and 3-methylamino-1-phenyl-2-buten-1-onate (3)), were taken as examples to study the influence of a substituent (H, Me) at the nitrogen atom on structure and spectral-luminescent properties. The replacement of the oxygen atom with the nitrogen atom in compound 1 led to a bathochromic shift of the monomeric luminescence maximum. Quantum chemical modeling of absorption spectra for compound 2 was carried out. In contrast to compounds 1 and 3, crystals of compound 2 are characterized by the formation of J-aggregates and excimers on their basis, which leads to a bathochromic shift of the luminescence spectrum and an increase in the luminescence intensity.     

Synthesis of 4,5-dichloro-3-cyanoisothiazole and its functional derivatives

By treating with phosphorus pentoxide the 4,5-dichloroisothiazole-3-carboxamide 4,5-dichloro-3-cyanoisothiazole was synthesized whose reactions with piperidine, phenyl-and benzylthiols occurred with replacement of the chlorine atom in the position 5 by the residue of the corresponding nucleophile. Reactions with sodium thiobytylate and also with sodium methylate in methanol led to the formation both of the products of chlorine substitution by BuS or MeO groups respectively and of addition products of methanol to the cyano group. The reaction of butanethiol with cyanoisothiazole in 2-propanol in the presence of sodium 2-propylate was more selective and resulted in the replacement of the chlorine atom in the position 5 by the residue of the butanethiol.     

Theoretical study of hydrogen bonded complexes of dimethyl disulfide or dimethyl peroxide with nitric acid

Ab initio and DFT calculations performed on the title systems revealed two types of structures for both DMDS-HNO₃ and DMDO-HNO₃ complexes. In both structures two hydrogen bonds are formed between the OH group interacting with one of sulfur (or oxygen) atoms and methyl CH group being a proton donor to one of the oxygen atoms of the NO₂ group of nitric acid. Depending on the location of the interacting methyl group with respect to the S or O acceptor of the main O-H?S(O) bond, the seven or eight-membered ring structures are formed. For all the structures, the most pronounced changes in geometric parameters upon interaction are observed for the proton donor molecule. The calculated binding energies are between −20.86 and −29.95 kJ/mol at MP2 and between −17.52 and −27.47 kJ/mol at B3LYP using the 6-311++G(2d,2p) basis set. The complexes involving disulfide are slightly weaker by ca. 6.7-8.6 kJ/mol than the corresponding peroxide complexes. The performed NBO analysis reveals that the charge transferred to σ*(OH) orbital of the nitric acid molecule comes mainly from the high p-character lone pair orbital of sulfur or oxygen atom being the hydrogen bond acceptor site in the disulfide or peroxide molecule.     

Mass-spectrometric study of 4-azaphenanthrene derivatives

The mass spectra of 15 compounds of the 4-azaphenanthrene series and their deutero analogs with bulky R substituents (R=-CCPh, -CH=CHPh, CHBr-CHBrPh,-CH=CHC₆H₄OCH₃-p, -COOH, -COOC₂H₅, and -CONHNH₂) in the ortho position relative to the nitrogen atom were studied. An intense [M-H]⁺ ion peak, the appearance of which is evidently due to a process involving cyclization of the carbon atom of the side chain with the nitrogen atom, is formed in the fragmentation of the styryl derivatives. The fragmentation of the compounds with a methyl group in the ortho position relative to the styryl grouping is accompanied by the formation of an intense [M-Ph]⁺ ion peak. An ortho effect of the carboxyl and carbethoxy groups adjacent to the methyl substituent is observed in the mass spectra of the investigated compounds. The data obtained make it possible to establish the structures of bulky substituents in the ortho position relative to the ring nitrogen atom and the position of the methyl group in the pyridine ring of monomethylated azaphenahthrenes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 659–665, May, 1979.     

Protonenresonanz-Untersuchungen an N,N-Dialkylaminoboranen. Substituentenabhängigkeit der Rotationsbarriere um die N?B-Bindung 1,2

The substituent dependence of the rotation barriers around the N? B bond in a series of N,N-dialkylaminoboranes was investigated by NMR. It was found that (1) there is a significant dependence on the size of the substituent, which arises from a ‘steric hindrance of mesomerism’ and (2) in certain cases exceptional facilitation of rotation occurs when alkyl groups on the boron atom are replaced by a chlorine atom or a second amino group. The lowering of the rotation barrier by about 10 kcal/mole in bisamino compounds compared with the corresponding monoamino compounds is explained on the basis of a lowering of the double bond character of each N? B bond owing to the participation of two N-atoms in the mesomerism of the ground state. This effect is much larger with amino groups than with chlorine atoms.     

Synthesis, spectroscopy, structures and photophysics of metal alkynyl complexes and polymers containing functionalized carbazole spacers

A new class of soluble and thermally stable group 10 platinum(II) poly-yne polymers functionalized with 9-arylcarbazole moiety trans-[-Pt(PBu₃)₂CCRCC-]_n (R = 9-arylcarbazole-3,6-diyl; aryl = p-methoxyphenyl, p-chlorophenyl) were prepared in good yields by the polycondensation polymerization of trans-[PtCl₂(PBu₃)₂] with HCCRCCH under ambient conditions. The optical absorption and emission properties of these polymetallaynes were investigated and compared with their bimetallic molecular model complexes trans-[Pt(Ph)(PEt₃)₂CCRCCPt(Ph)(PEt₃)₂] as well as their group 11 gold(I) and group 12 mercury(II) neighbors [(PPh₃)AuCCRCCAu(PPh₃)] and [MeHgCCRCCHgMe]. The structures of all the compounds were confirmed by spectroscopic methods and by X-ray crystallography for selected model complexes. The influence of the heavy metal atom and the 9-aryl substituent of carbazole on the evolution of lowest electronic singlet and triplet excited states is critically characterized. It was shown that the organic-localized phosphorescence emission can be triggered readily by the heavy-atom effect of group 10-12 transition metals (viz., Pt, Au, and Hg) with the emission efficiency generally in the order Pt > Au > Hg. These carbazole-based organometallic materials possess high-energy triplet states of 2.68 eV or higher which do not vary much with the substituent of 9-aryl group.     

Fluorothiazynes, 50 years old and still exciting: electrophilic attack at the thiazyl nitrogen of NSF2NS(O)F2

One of the most interesting compounds in sulfur nitrogen fluorine chemistry is NSF₂NS(O)F₂ (3) (reported by Glemser and Höfer 30 years ago): in the NS backbone a triple and a double bond are connected by a single bond. Electrophiles (metal cations, fluoro Lewis acids, “CH₃⁺”) attack this multifunctional system exclusively at the thiazyl nitrogen of the triple bond. [M(NSF₂NS(O)F₂)₄][AsF₆]₂ (M = Ni (4b), Cu (4c)), [Re(CO)₅(NSF₂NS(O)F₂)][AsF₆]⁻ (5), F₅A·NSF₂NS(O)F₂ (A = As (6), Sb (7)), F₃B·NSF₂NS(O)F₂ (8) and [H₃CNSF₂NS(O)F₂]⁺[AsF₆]⁻ (9) were isolated. The X-ray structures of 4c, 6, 8 and 9 are reported, bonding in these complexes is compared with the recently reported related NSAr₂NS(X)Ar₂ (X = O, NH) species.     

Molecular complexes of 4-nitropyridine and 4-nitroquinoline <Emphasis Type="Italic">N</Emphasis>-oxides with boron trifluoride and hydrogen chloride as intermediates in S<Subscript>N</Subscript>Ar reactions

Complexation of 4-nitropyridine N-oxides with ν- (BF₃, HCl) and π-acceptors (tetracyanoethylene, chloranil, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, 7,7,8,8-tetracyanoquinodimethane) activates the nitro group to nucleophilic replacement by chlorine. Adducts formed by 4-nitropyridine and 4-nitroquinoline N-oxides with boron trifluoride and hydrogen chloride were studied by IR spectroscopy. It was shown that these complexes belong to the n,ν type and that the donor-acceptor interaction therein involves the oxygen atom of the N-oxide group.