Synthesis and structural characterization of Palladium(II) complex bearing <Emphasis Type="Italic">N</Emphasis>-Heterocyclic Carbene

Trans-Bis[1,3-bis(2,4-dimethylphenylimidazolidin-2-ylidene)]dichloropalladium(II), 4, was prepared from 1,3-bis(2,4-dimetilphenyl)imidazoliniumchloride. The crystal and molecular structure of 4 have been determined by single crystal X-ray diffraction. The title compound, C₃₈H₄₄N₄PdCl₂, crystalizes in the monoclinic space group P 21/n with a = 13.8713(9) Å, b = 12.1365(6) Å, c = 21.5499(15) Å. The Pd atom has a slightly distorted square planar coordination geometry. The molecules of the title compound are linked by C–H···Cl weak hydrogen bonds into two-dimensional sheets parallel to the (001) plane. In addition, the title compound was characterized by elemental analyses and NMR spectroscopy.     

Synthesis and crystal structure of a new molecular complex of fullerene C70, 4BNDY·3C70·4C6H6 (BNDY is binaphtho[1,8-d,e]-1,3-dithiin-2-ylidene)

A new C₇₀-based molecular complex 4BNDY·3C₇₀·4C₆H₆ (1) (BNDY is binaphtho[1,8-d.e]-1,3-dithiin-2-ylidene) was prepared, and its full X-ray diffraction study at room temperature was performed. The C₇₀ molecules in crystal 1 are ordered in different ways, and their ordering depends on van der Waals interactions between them and nonplanar BNDY molecules in the boat conformation. The neighboring BNDY molecules in the structure are bound to each other by π-π interactions. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 99–102, January, 2000.     

Synthesis and crystal structure of the molecular complex of fullerence C60 with 2-(4-thiono-1,3-dithiolan-5-ylidene)-4,5-dimethyl-1,3-diselenol (C60·2DTDS)

A new molecular complex of fullerene C₆₀ with 2-(4-thiono-1,3-dithiolan-5-ylidene)-4,5-dimethyl-1,3-diselenol (C₆₀·2DTDS) was synthesized for the first time. The crystal and molecular structures of C₆₀·2DTDS were established by X-ray diffraction analysis. The crystal structure of C₆₀·2DTDS is layered: the layers of fullerene C₆₀ molecules alternate with those of DTDS molecules. The molecules of C₆₀ and DTDS are associated by shortened C...Se, C...S, and C...C contacts forming a three-dimensional network of secondary interactions in the crystal. The C₆₀·2DTDS crystals have a specific feature: the absence of shortened C...C contacts between the nearest C₆₀ molecules despite the short distances between their centers, 9.948(2) and 10.054(2) Å. The electrochemical properties of DTDS were studied by cyclic voltammetry in CH₂Cl₂/0.05M Bu₄NPF₆ at room temperature. DTDS undergoes reversible one-electron reduction to a radical anion [E ^o=?1.81 V (Fc^0/+)] and reversible one-electron oxidation to a radical cation [E ^o=+0.37 V (Fc^0/+)]. The degree of charge transfer in C₆₀·2DTDS, ΔN=0.18, calculated from the electrochemical parameters of DTDS and C₆₀ indicates that this compound is a molecular complex with a partial charge transfer.     

Synthesis,Structures and DFT Studies of Imido‐bridged and (Bis)ligand‐coordinated Titanium Complexes

Syntheses and structures of five imido‐bridged dinuclear titanium complexes and two (bis)ligand‐coordinated mononuclear titanium complexes are reported. Addition of 1 or 2 equiv. of Schiff base ligand (((1H‐pyrrol‐2‐yl)methylene)amino)‐2,3‐dihydro‐1H‐inden‐2‐ol (H₂L) to Ti(NMe₂)₄ resulted in transamination with 4 equiv. of dimethylamides generating a (bis)ligand‐coordinated complex Ti(L)₂ ( 1 ). Treatment of Ti(NMe₂)₄ with 1 equiv. of ^tBuNH₂ followed by addition of 1 equiv. of H₂L afforded an imido‐bridged complex [Ti(L)(N^tBu)]₂ ( 2 ). 1:1:1:1 reaction of Ti(NMe₂)₄/RNH₂/H₂L/py(or phen) produced imido‐bridgedcomplexes [Ti(L)(NPh)(py)]₂ ( 3 ), [Ti(L)(4‐F‐PhN)(py)]₂·Tol ( 4 ·Tol), [Ti(L)(4‐Cl‐PhN)(py)]₂·Tol·THF ( 5 ·Tol·THF), [Ti(L)(4‐Br‐PhN)(py)]₂·Tol ( 6 ·Tol) and a (bis)ligand‐coordinated complex Ti(L)₂·phen ( 7 ) (py = pyridine, phen = 1,10‐phenanthroline). Attempts to prepare the monomeric titianium imido complexes were unsuccessful. DFT studies show that the assumed compound which contains Ti = N species is less stable than imido‐bridged Ti‐N(R)‐Ti complexes, providing the better understanding of the experimental results.     

A novel reaction of (2a7-trinito-9H-fluoren-9-ylidene)-propanedinitrile with N-arylisoindolines

N-Arylisoindolines 1a-c reacted with (2,4, 7-trinitro-9H-fluoren-9-ylidene)propanedinitrile ( A ) in pyridine with admission of air via a net α-H-atom abstraction and formation of [3-(2-aryl-3-arylimino-2,3-dihydro- 1H-isoindol-1-ylidene)-2-aryl-2,3-dihydro-1H-isoindol-1-ylidene]propanedinitriles 2a-c , N-[2-aryl-3-(2-aryl-3-arylimino-2,3-dihydro-1H-isoindolyl-1-idene)-2,3-dihydro-1H-isoindol-1-ylidene]arenamines 3a, b , N, N'-[2-aryl-1H-isoindole-1,3(2H)-diylidene]bisarenamines 4a, b and N-arylphthalimides 5a-c in moderate yields. 2,4,7-Trinitro-9-fluorenone as well as one reduction product each of the latter and of A, namely compounds 6 and 7 , respectively, are also found. The structure of 2b has been unambiguously confirmed by an X-ray crystal structure analysis. A rationale for the conversions observed is presented. These involve dehydrogenation and oxidative couplings of 1a-c as well as transfer of N-aryl fragment from 1a-c to intermediate products.     

Synthesis, biological activity and crystal structure of ethyl 6-amino-8-(4-methoxy phenyl)-9-nitro-2,3,4,8-tetrahydropyrido[2,1b][1,3]thiazine-7-carboxylate

The compound ethyl 6-amino-8-(4-methoxy phenyl)-9-nitro-2,3,4,8-tetrahydropyrido[2,1b][1,3]thiazine-7-carboxylate (C₁₄H₂₂N₄O₄S₂) has been synthesized by multicomponent reactions, and characterized by ¹H NMR, IR, and X-ray diffraction. The crystal structure analysis shows that the thiazinane ring displays a half-chair conformation. The benzene ring is almost vertical to the tetrahydro-pyridine ring. Intramolecular H-bonding of N–H···O type exists and completes an S (6) ring. In the crystal, the molecules are connected into a 3D network by a N–H···O and C–H···O intermolecular hydrogen bond. The bioassay indicates that the compound shows moderate insecticidal activity against Aphis craccivora.     

N-(1,3-Thiazol-5(4H)-yliden)amine aus 1,3-dipolaren Cycloadditionen von Aziden mit 1,3-Thiazol-5(4H)-thionen

N-(1,3-Thiazol-5(4H)-ylidene)amines via 1,3-Dipolar Cycloaddition of Azides and 1,3-Thiazol-5(4H)-thiones Organic azides 5 and 4,4-dimethyl-2-phenyl-1,3-thiazol-5(4H)-thione ( 2 ) in toluene at 90° react to give the corresponding N-(1,3-thiazol-5(4H)-ylidene)amines (= 1,3-thiazol-5(4H)-imines) 6 in good yield (Table). A reaction mechanism for the formation of these scarcely investigated thiazole derivatives is formulated in Scheme 3: 1,3-Dipolar azide cycloaddition onto the C?S group of 2 leads to the 1:1 adduct C . Successive elimination of N₂ and S yields 6 , probably via an intermediate thiaziridine E .     

Photochemistry of N-(2-Cyclohexen-1-ylidene) alkylamines

Irradiation (λ = 254 nm) of N-(4,4,6,6-tetramethyl-2-cyclohexen-1-ylidene)-1,1,3,3-tetramethyl-2-cyclohexen-1-ylidene-1,1,3,3-tetramethylbutylamine (7d) , which in turn is photodecomposed by light of the same wavelength, but at a four times slower rate than it is formed. The rate of formation of photoproduct 7d is a function of the concentration of starting material 1d , suggesting the involvement of a bimolecular ( 1d ^* + 1d ) step. The structure of 7d was established by spectroscopy and by its hydrolysis to 3-cyclohexyl-4,4,6,6-tetramethyl-2-cyclohexenone ( 8 ). The previously made assumption that N-(2-cyclohexen-1-ylidene)cyclohexylamine ( 1a ) and 2,3,4,4a,5,6-hexahydroquinolines 2 photorearrange to N-cyclohexylidenecyclohexanamine 3a and 3,4,4a,5,6,8a-hexahydroquinolines 4 , respectively, via a light-induced 1,3-hydrogen shift proves incorrect.     

Heterocyclen aus Bis(alkoxycarbonyl)keten-ethylen-acetalen ( = Dialkyl-2-(1,3-dioxolan-2-yliden)propan-1,3-dioate). Synthese und Eigenschaften einer neuen Klasse von Pyrazolium-Betainen

Heterocycles Starting from Bis(alkoxycarbonyl)ketene Ethylene Acetals ( = Dialkyl 2-(1,3-Dioxolan-2-ylidene)propane-1,3-dioate). Synthesis and Properties of a New Class of Pyrazolium Betaines The readily available bis(alkoxycarbonyl)ketene ethylene acetals 1 react with bifunctional nucleophiles to give heterocycles 2–5 (Scheme 1). Their reactions with N,N-dialkylhydrazines lead to the pyrazolium betaines 7a–f (Scheme 4). Cyclic N,N-dialkylhydrazines give spiro compounds 7d–f . The reaction of thioketene acetal 12 and of the derivative 15 of methanetricarboxylic acid with N,N-dimethylhydrazine results in the formation of 3-(methylthio)- and 3-methoxypyrazolium betaine 7g and 7h , respectively (Scheme 4). The chemical reactivity of the synthesized pyrazolium betaines 7 was tested. The structure of the 3-(methylthio) derivative 7g was determined by X-ray analysis.     

Synthesis of imidazo[5,4-d] [1,3]thiazines: X-ray structure of N-methyl-N′-[5-(methylamino)-3-nonylimidazo[5,4-d] [1,3]thiazin-7(3H)-ylidene]thiourea

N-Alkyl-N′-[5-(alkylamino)-3-alkylimidazo[5,4-d] [1,3]thiazin-7(3H)-ylidene]thioureas were obtained by the reaction of 1-substituted 5-amino-4-cyanoimidazoles with alkyl isothiocyanates. The structure of this heterocyclic system was confirmed by single crystal X-ray diffraction analysis.     

Molecular and crystal structure of 4-trifluoro-2-[2-(4-fluorophenyl)hydrazine-1-ylidene]-1-(thiophen -2-yl)butane-1,3-dione

Single crystal X-ray diffraction is used to determine the crystal and molecular structure of 4-trifluoro-2-[2-(4-fluorophenyl)hydrazine-1-ylidene]-1-(thiophen-2-yl)butane-1,3-dione. Crystallographic data for C₁₄H₈F₄N₂O₂S are as follows: a = 8.2723(6) ?, b = 9.3009(7) ?, c = 9.9895(7) ?; α = 79.224(2)°, β = 75.851(2)°, γ = 72.337(2)°. Triclinic crystal system, P-1 space group, d _x = 1.622 g/cm³, V = 704.83(9) ?³, μ = 0.286 mm⁻¹, crystal size 0.30×0.20×0.20 mm, R1 = 0.0891, wR2 = 0.1989.     

The molecular and crystal structure of N-(4-n-butyloxybenzylidene)-4′-ethylaniline (4O.2) and N-(4-n-heptyloxybenzylidene)-4′-hexylaniline (7O.6)

Abstract

The molecular and crystal structure of N-(4-n-butyloxybenzylidene)-4′-ethylaniline (4O.2) and the homologue N-(4-n-heptyloxybenzylidene)-4′-hexylaniline (7O.6) have been solved (at room temperature) by direct methods. The crystals of both compounds belong to the triclinic system with space group P1 with two molecules per unit cell. 4O.2: a = 5·531(2), b = 7·592(3), c = 19·746(7) Å, α = 86·66(2), β = 88·15(2), γ = 90·29(2)° 7O.6: a = 5·420(2), b = 8·307(3), c = 28·057(7) Å, α = 91·69(2), β = 89·76(2), γ = 108·02(2)°. The structures were refined by full-matrix least-squares calculations to R = 0·036 for 2297 observed reflections for 4O.2 and to R = 0·037 for 2150 reflections for 7O.6. The conformations in the asymmetric units of the two compounds differ considerably: The planes of the two phenyl rings of 4O.2, forming the mesogenic core of the molecule, are twisted at 61·2° to each other and the butoxy group contains a gauche conformation. In contrast the heptoxy chain of 7O.6 forms an all trans-conformation which lies almost in one plane with the two coplanar phenyl rings. The hexyl group also exists in an extended form, in a plane which is rotated against the plane of the mesogenic unit. The packing in the crystalline state of the two homologues exhibits a layered structure along c*; in 4O.2 these layers are separated, but in 7O.6 they are interdigitated. The compensation of the dipole moments of the C?O?C and C?N?C bonds occurs similarly in both structures: molecular orientations parallel to the a, c-plane in which the long axes of the molecules points in the same direction are packed in antiparallel fashion along b*.     

Synthesis,spectral, and thermal properties,and crystal structure of cobalt (III) complex derived from Imazameth

A novel metal–organic coordination compound [Co(Imazameth)₃]·0.5DMF·4H₂O (where Imazameth = (±)-2-(4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H- imidazol-2-yl)-5-methyl-3-pyridinecarboxylic acid; DMF = N,N-dimethylformamide) has been prepared and characterized by spectral method (IR), elemental analysis, thermal gravimetric analysis (TGA), fluorescence properties, and single crystal X-ray diffraction techniques. It crystallizes in the trigonal system, space group R-3 and the asymmetric unit contains four water molecules. The four lattice water molecules and their symmetric equivalent form a slight distorted cubical water cluster through hydrogen bonds. The O···O bonds of the water cluster are in the range of (2.80(7)–2.99(2) Å), and O···O···O angles are in the range of (82.54°–101.38°). In the cubical water clusters, the six O(5) atoms of each cube are connected to six O(1) atoms of the six molecules (O(1)···O(5) = 2.77(1) Å) by hydrogen bonding, respectively. The Co atom is six-coordinated by six N atoms in distorted octahedron coordination geometry. Intramolecular N–H···O and intermolecular O–H···O hydrogen bonds result in the formation of a supermolecular crystal, in which they seem to be effective in the stabilization of the structure. The complex displays strong fluorescence property and good thermal stability.     

新型不对称吡喃鎓方酸菁染料的晶体结构

通过缓慢挥发溶剂法得到一种不对称吡喃方酸菁染料的单晶,测定了其晶体结构.其晶系为三斜晶系,空间群为P1,a=0.9228(4),b=1.4122(6),c=0.6124(3)nm,α=93.97(4),β=98.14(5),γ=71.05(4),V=0.7470(6)nm³,Z=1.用晶体结构数据解释了此不对称染料的¹H-NMR谱.     

A joint theoretical and experimental structural study of two novel 1,2,4-triazolo[3,4-<Emphasis Type="Italic">b</Emphasis>]-1,3,4-thiadiazine derivatives

In this study, two novel 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine derivatives, 3-[2-(4-methoxyphenyl)ethyl]-6-phenyl-7H-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine (compound 1) and 3-[2-(3,4,5-trimethoxyphenyl)ethyl]-6-phenyl-7H-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine (compound 2), having analgesic–anti-inflammatory activity were synthesized and characterized by IR, ¹H-NMR, and mass spectroscopic techniques besides elementary analysis. Additionally, the structures and molecular packings of the mentioned compounds have been investigated by X-ray single crystal diffraction. The six-membered thiadiazine ring adopts the screw boat conformation in both the compounds. In the crystal packings of the compounds 1 and 2, C–H···N and C–H···O interactions link the molecules into a two-dimensional network and generate infinite chains. Furthermore, C–H···π intermolecular interactions provide further stability to the molecular packing in both the molecules. The conformers have been predicted by the potential energy surface scan employing the AM1 method. Geometry optimizations and electrostatic properties have been obtained using AM1 and ab initio quantum methods.     

Synthesis,Crystal Structures,and Thermal Properties of New Zinc(II) Thiocyanato Coordination Compounds

Reaction of zinc(II) thiocyanate with pyrazine, pyrimidine, pyridazine, and pyridine leads to the formation of new zinc(II) thiocyanato coordination compounds. In bis(isothiocyanato‐N)‐bis(μ₂‐pyrazine‐N,N) zinc(II) ( 1 ) and bis(isothiocyanato‐N)‐bis(μ₂‐pyrimidine‐N,N) zinc(II) ( 2 ) the zinc atoms are coordinated by four nitrogen atoms of the diazine ligands and two nitrogen atoms of the isothiocyanato anions within slightly distorted octahedra. The zinc atoms are connected by the diazine ligands into layers, which are further linked by weak intermolecular S ··· S interactions in 1 and by weak intermolecular C–H ··· S hydrogen bonding in 2 . In bis(isothiocyanato‐N)‐bis(pyridazine‐N) ( 3 ) discrete complexes are found, in which the zinc atoms are coordinated by two nitrogen atoms of the isothiocyanato ligands and two nitrogen atoms of the pyridazine ligands. The crystal structure of bis(isothiocyanato‐N)‐tetrakis(pyridine‐N) ( 4 ) is known and consists of discrete complexes, in which the zinc atoms are octahedrally coordinated by two thiocyanato anions and four pyridine molecules. Investigations using simultaneous differential thermoanalysis and thermogravimetry, X‐ray powder diffraction and IR spectroscopy prove that on heating, the ligand‐rich compounds 1 , 2 , and 3 decompose without the formation of ligand‐deficient intermediate phases. In contrast, compound 4 looses the pyridine ligands in two different steps, leading to the formation of the literature known ligand‐deficient compound bis(isothiocyanato‐N)‐bis(pyridine‐N) ( 5 ) as an intermediate. The crystal structure of compound 5 consists of tetrahedrally coordinated zinc atoms which are surrounded by two isothiocyanato anions and two pyridine ligands. The structures and the thermal reactivity are discussed and compared with this of related transition metal isothiocyanates with pyrazine, pyrimidine, pyridazine, and pyridine.     

Synthesis,structure and physical properties of the one-dimensional chain complex of tetrathiafulvalene carboxylate

A new Co(II) coordination polymer bearing TTF carboxylate group, [{Co₂(trioTTF)₂(H₂O)₆}·5H₂O]_n (1) (trioTTF = 2-(5,6,8,9,11,12,14,15-octahydro-[1,3]dithiolo[4,5-h][1,4,13,7,10]trioxadithiacyclopentadecin-2-ylidene)-1,3-dithiole-4,5-dicarboxylate), has been prepared and characterized. In the structure of 1, shorter intermolecular S····S contacts (3.565 Å) are found between the trioTTF groups from neighboring chains. The electric conductivity of 1 is poor due to the bulky crown-ether group, but it exhibits ferromagnetic interaction at low temperature.     

1,3-dialkyl- and 1,3-diaryl-3,4,5,6-tetrahydropyrimidin-2-ylidene rhodium(i) and palladium(II) complexes: synthesis, structure, and reactivity

The synthesis of novel 1,3-diaryl- and 1,3-dialkylpyrimidin-2-ylidene-based N-heterocyclic carbenes (NHCs) and their rhodium(i) and palladium(II) complexes is described. The rhodium compounds bromo(cod)[1,3-bis(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene]rhodium (7), bromo(cod)(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)rhodium (8) (cod=eta(4)-1,5-cyclooctadiene, mesityl=2,4,6-trimethylphenyl), chloro(cod)(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)rhodium (9), and chloro(cod)[1,3-bis(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene]rhodium (10) were prepared by reaction of [[Rh(cod)Cl](2)] with lithium tert-butoxide followed by addition of 1,3-dimesityl-3,4,5,6-tetrahydropyrimidinium bromide (3), 1,3-dimesityl-3,4,5,6-tetrahydropyrimidinium tetrafluoroborate (4), 1,3-di-2-propyl-3,4,5,6-tetrahydropyrimidinium bromide (6), and 1,3-di-2-propyl-3,4,5,6-tetrahydropyrimidinium tetrafluoroborate, respectively. Complex 7 crystallizes in the monoclinic space group P2(1)/n, and 8 in the monoclinic space group P2(1). Complexes 9 and 10 were used for the synthesis of the corresponding dicarbonyl complexes dicarbonylchloro(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)rhodium (11), and dicarbonylchloro[1,3-bis(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene]rhodium (12). The wavenumbers nu(CO I)/nu(CO II) for 11 and 12 were used as a quantitative measure for the basicity of the NHC ligand. The values of 2062/1976 and 2063/1982 cm(-1), respectively, indicate that the new NHCs are among the most basic cyclic ligands reported so far. Compounds 3 and 6 were additionally converted to the corresponding cationic silver(i) bis-NHC complexes [Ag(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)(2)]AgBr(2) (13) and [Ag[1,3-bis(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene](2)]AgBr(2) (14), which were subsequently used in transmetalation reactions for the synthesis of the corresponding palladium(II) complexes Pd(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)(2) (2+)(Ag(2)Br(2)Cl(4) (4-))(1/2) (15) and Pd[1,3-bis(2-propyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene)(2)]Cl(2) (16). Complex 15 crystallizes in the monoclinic space group P2(1)/c, and 16 in the monoclinic space group C(2)/c. The catalytic activity of 15 and 16 in Heck-type reactions was studied in detail. Both compounds are highly active in the coupling of aliphatic and aromatic vinyl compounds with aryl bromides and chlorides with turnover numbers (TONs) up to 2000000. Stabilities of 15 and 16 under Heck-couplings conditions were correlated with their molecular structure. Finally, selected kinetic data for these couplings are presented.     

Synthesis and crystal structure of 2-{5-[2-(2,6-dichlorophenylamino)benzyl]-4-p-tolyl-4H-1,2,4-triazol-3-ylthio}acetate

The compound 2-{5-[2-(2,6-dichlorophenylamino)benzyl]-4-p-tolyl-4H-1,2,4-triazol-3-ylthio}acetate has been prepared and characterized by IR, ¹H NMR, ¹³C NMR and mass spectra. The crystal and molecular structure were further confirmed using single crystal X-ray diffraction. The crystal structure has been found to be stabilized by intermolecular C–H···O interaction generating bifurcated hydrogen bonds whereas the C–H···N interactions generate chain of molecules. The intramolecular N–H···N hydrogen bond forms a ring with S(7) graph-set motif.