Structure Of Bis Research Articles

N‐phosphinyl ureas: Synthesis, characterization, X‐ray structure, and in vitro evaluation of antitumor activity

AbstractA new series of N‐phosphinylureas 5b, 6a–7c was synthesized and characterized by 1H, 13C, 31P NMR, IR, and elemental analysis. The three‐dimensional structure of 5b has been determined by X‐ray crystallography. The crystal structure revealed the existence of four independent molecules. All structures form two chains with different arrangements and connect to each other via hydrogen bonds to produce two‐dimensional polymeric chains. The cytotoxicity of cyclophosphamide (a standard antitumor compound) and its nine analogues with formula R1C6H4 NHC(O)NHP(O)XCH2C(R2)2 CH2Y(X = Y = NH, R2 = CH3, R1 = H (5a), CH3 (5b), NO2 (5c), X = O, Y = NH, R2 = H, R1 = H (6a, CH3 (6b), NO2 (6c), and X = Y = O, R2 = CH3, R1 = H (7a), CH3 (7b), NO2 (7c)) as well as phenyl urea were evaluated in vitro against three human tumor cell lines K562, MDA‐MB‐231, and HepG2. The results showed that most of the compounds have significant activity against the selected cell lines. Also, HepG2 cells were more sensitive to all the tested compounds than other cell lines. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 23:74–83, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20754

Novel 4-azasteroidal N-glycoside analogues bearing sugar-like D ring: Synthesis and anticancer activities

A series of novel N-glycoside analogues with 4-azasteroid moiety bearing sugar-like D ring were conveniently synthesized by constructing the core dihydropyran ring embedded in 4-azasteroidal skeleton which was prepared from 4-aza-5α-androst-3,17-dione 1 in four steps. The structure of 6b were unambiguously proved by the appropriate X-ray structural analysis. Anticancer activity was found for all of the analogues with purinyl moiety against breast cancer (MCF-7), human neuroblastoma (SK-N-SH), cervical cancer cell (HeLa) and prostatic cancer (PC-3), while the analogue 7 containing 1,2,4-triazole heterocycle as the nucleobase was inactive against all of the tested cancer cell lines. The biology results showed the purinyl moiety attached to the pyran ring of 6a-d, substituent at 6'-position of purine base and introduction of a halogen atom at 2'-position of 6'-chloropurine had obviously effect on the evaluated anticancer activity.

Synthesis and Structure of bis(cyclohexylmethyl) 3,6-bis(4-chlorophenyl)-1,2,4,5-tetrazine-1,2-dicarboxylate

Bis(cyclohexylmethyl) 3,6-bis(4-chlorophenyl)-1,2,4,5-tetrazine-1,2-dicarboxylate was prepared from cyclohexylmethyl chloroformate and 3,6-bis(4-chlorophenyl)-1,2(or 1,4)-dihydro-1,2,4,5-tetrazine and its structure was determined by X-ray diffraction. This reaction yields the title compound rather than bis(cyclohexylmethyl) 3,6-bis(4-chlorophenyl)-1,2,4,5-tetrazine-1,4-dicarboxylate. The 2,3-diazabutadiene group in the central six-membered ring of tetrazine is not planar and the tetrazine ring has a twist conformation.

A regioselective synthesis of some new pyrazol-1′-ylpyrazolo[1,5- a]pyrimidines in aqueous medium and their evaluation as antimicrobial agents

An efficient and environmental benign regioselective synthesis of some new pyrazol-1′-ylpyrazolo[1,5- a]pyrimidines ( 7b– h) has been accomplished via treatment of 3(5)-amino-5(3)-hydrazinopyrazole dihydrochloride ( 5) with several unsymmetrical 1,3-diketones ( 6b– h) using water as a solvent without any catalysts or additives. The structure of 7b– h was established on the basis of rigorous analysis of 1H, 13C NMR, IR spectral data and MS. Eight compounds ( 7a– h) were screened for their antibacterial activity against two gram-positive and two gram-negative bacteria and compounds ( 7a, b, d and e) for antifungal activity against four phytopathogenic fungi. Compounds 7c and 7e manifest rather broad antibacterial activity than standard antibiotics. One lead compound, 7a (10 mg/ml and 200 mg/ml) exhibited equipotent or more potent antifungal activity against all tested microorganisms than standard drug.

Synthesis and Crystal Structures of μ‐Oxido‐ and μ‐Hydroxido‐Bridged Dinuclear Iron(III) Complexes with an N2O Donor Ligand – A Theoretical Study on the Influence of Weak Forces on the Fe–O–Fe Bridging Angle

AbstractThe synthesis and crystal structures of three nonheme diiron(III) complexes with a tridentate N,N,O Schiff‐baseligand, 2‐({[2‐(dimethylamino)ethyl]imino}methyl)phenol (HL), are reported. Complexes [Fe2OL2(NCO)2] (1a) and [Fe2OL2(SAL)2]·H2O [SAL = o‐(CHO)C6H4O–] (1b) are unsupported μ‐oxido‐bridged dimers, and [Fe2(OH)L2(HCOO)2(Cl)] (2) is a μ‐hydroxido‐bridged dimer supported by a formato bridging ligand. All complexes have been characterized by X‐ray crystallography and spectroscopic analysis. Complex 1b has been reported previously; however, it has been reinvestigated to confirm the presence of a crucial water molecule in the solid state. Structural analyses show that in 1a the iron atoms are pentacoordinate with a bent Fe–O–Fe angle [142.7(2)°], whereas in 2 the metal centers are hexacoordinate with a normal Fe–OH–Fe bridging angle [137.9(2)°]. The Fe–O–Fe angles in complexes 1a and 1b differ significantly to those usually shown by (μ‐oxido)FeIII complexes. A theoretical study has been performed in order to rationalize this deviation. Moreover, the influence of the water molecule observed in the solid‐state structure of 1b on the Fe–O–Fe angle is also analyzed theoretically.

The synthesis and structure of bis(pyridine-2-carboxy)difluoro(λ6)- and bis(pyridine-2-carboxy)fluorophenyl(λ5)siliconium

Reactions of silicon fluorides with picolinic acid (PicH) and its O-trimethylsilyl derivative afforded neutral hexa- or pentacoordinate complexes F2SiPic2 (5) and PhFSiPic2 (6). According to NMR data, complex 5 with SiO2N2F2 fragment exists as a mixture of two isomers with equivalent 5a and non-equivalent 5b fluorine atoms in a 1.5:1 ratio. Quantum chemical calculations at the B3LYP/6-311G** level confirm the stability of the lowest-energy transstructure of 5a.

Synthesis and characterization of bis (4-maleimidophenyl) fluorene and its semi interpenetrating network membranes with polyether imide (Ultem ® 1000)

A semi-interpenetrating network (semi-IPN) of bis (4-maleimidophenyl) fluorene (cardo-BMI) and polyether imide (PEI, Ultem ® 1000) was prepared. The structure of bis (4-maleimidophenyl) fluorene and the corresponding semi-IPNs was determined by nuclear magnetic resonance and Fourier transform infrared spectroscopy, respectively. The thermal properties of the cardo-BMI and semi-IPNs were evaluated by thermogravimetry and differential scanning calorimetry. The semi-IPNs exhibited thermal stability up to 480 °C. The morphology of the semi-IPNs was evaluated by scanning electron microscopy. Asymmetric membranes were prepared from the semi-IPN material by the wet phase inversion method. The pure gas permeation properties of the PEI and semi-IPN membranes were evaluated for oxygen (O 2), nitrogen (N 2), carbon dioxide (CO 2) and methane (CH 4) by the constant pressure and variable volume method at an absolute feed pressure of 0.69 MPa at 22 °C. The CO 2/N 2 selectivity of 39.2 ± 3.0 with a CO 2 permeance of 18.3 ± 4.0 GPU of semi-IPN membrane was higher than the PEI membranes (selectivity 21.6 ± 4.1 and CO 2 permeance 0.5 ± 0.1 GPU). The highest CO 2/CH 4 selectivity of the semi-IPN membrane was 49.3 ± 3.5 compared to 37 for a PEI dense film. Among the semi-IPN membranes, those with 5 wt% cardo-BMI exhibited better performance than the 1% and 10%.

Synthesis and characterization of bis(O,O′-diisopropylmonothiophosphato)nickel(II) adducts and molecular structures of bis(pyridine)bis(O,O′-diisopropylmonothiophosphato)nickel(II) complex

The present work demonstrates the synthesis and characterization of adducts with bis(O,O′-diisopropylmonothiophosphato)nickel(II) complex, Ni{S(O)P(OiPr)2}2(L) n (n = 2, L = pyridine, 2-picoline, 3-picoline; n = 1, L = 2,2′-bipyridyl and 1,10-phenanthroline). The crystallographic investigation of Ni{S(O)P(OiPr)2}2(C5H5N)2 reveals distorted octahedral geometry around the central nickel(II) atom. The monothiophosphate moieties show anisobidentate coordination to the central metal, while the pyridine ligands are in cis positions. These nickel(II) adducts were characterized by elemental analysis, a range of spectroscopic techniques, and magnetic susceptibility measurement.

Structure and spectroscopic properties of bis(1-carboxyethyl-3-aminopyridinium) hydrobromide monohydrate

The structure of bis(1-carboxyethyl-3-aminopyridinium) hydrobromide monohydrate, (3-NH 2PB2) 2HBr⋅H 2O ( 1), has been studied by X-ray diffraction, B3LYP/6-311G(d,p) calculations, FTIR and NMR spectroscopy and calorimetric measurements. The compound crystallizes in orthorhombic, space group Pbca. The Br anion and water molecules are positionally disordered so that Br(1) and O(1w) are located at the same positions with the same average occupations and they form O(1w)H⋯Br bonded zigzag chains along [1 0 0], with the Br⋯O(1w)⋯Br and O(1w)⋯Br⋯O(1w) angles equal 121.0(3)°. These chains are connected to the O(1)⋯H(1)⋯O(11) bonded cations through NH⋯Br and NH⋯O(1w) bonds. A pair of 3-NH 2PB2 molecules is bridged by a short symmetric O(1)·H·O(11) hydrogen bond of 2.462(6) Ǻ. The FTIR spectrum of ( 1) shows a broad and intense absorption in the 1500–400 cm −1 range, similar to that in the spectra of type A acid salts of carboxylic acids and other 2:1 betaine complexes with mineral acids. The assignment of the anharmonic experimental solid-state vibrational frequencies of the compound investigated is proposed based on the second-derivative spectrum ( d 2). Correlations between the experimental 13C and 1H NMR chemical shifts ( δ exp) and the GIAO/B3LYP/6-311G(d,p) calculated magnetic isotropic shielding constants ( σ cal) in DMSO-d 6, δ exp = a + b· σ calc, are reported.

A sulfur(II) complex of a dithioimidodiphosphinate

The structure of bis[P,P-di-tert-butyl-N-(di-tert-butylphosphorothioyl)phosphinimidothioato-κS]sulfur(II) toluene solvate (systematic name: 5,13-dibutyl-7,7,11,11-tetramethyl-8,9,10-trithia-6,12-diaza-5λ(5),7λ(5),11λ(5),13λ(5)-tetraphosphaheptadeca-6,11-diene-5,13-dithione toluene solvate), C(32)H(72)N(2)P(4)S(5)·C(7)H(8), at 173 K has monoclinic (C2/c) symmetry. The S(II) centre of (SP(t)Bu(2)NP(t)Bu(2)PS-)(2)S is coordinated in an S-monodentate fashion to two [(SP(t)Bu(2))(2)N](-) monoanions. The molecule resides on a twofold axis which bisects the central S atom. The internal P-S distance is ca 0.19 Å longer than the terminal P=S bond and there is a compensating alternation in P-N bond distances. The central S-S-S angle is 106.79 (8)°. The toluene solvent molecule is disordered about a twofold axis.

Synthesis, QSAR and anti-HIV activity of new 5-benzylthio-1,3,4-oxadiazoles derived from α-amino acids

2-(1-[(4-Chloro/methylphenylsulfonylamino)alkyl]-5-thioxo-4,5-dihydro-1,3,4-oxadiazoles (4a–e) were synthesized, in four steps, via the sulfonyl derivatives of l-amino acids (l-alanine, l-methionine and l-phenylalanine) 1a–e, the esters 2a–e, the hydrazides 3a–e and finally the cyclization to 4a–e. Alkylation of 4a–e with 1.0 mole eq. of substituted benzyl halides furnished S-benzyl derivatives 5a–t, while 1.1 mole eq. yielded major 5a–t and minor amount of 6a–d. Alternatively, treatment of 4a–e with 2.0 mole eq. of substituted benzyl halides furnished 6a–d only. The structures of 5b and 5l were further confirmed by single crystal X-ray analysis. Compounds 5a–t and 6a–d showed no selective inhibition against HIV-1 and HIV-2 replication in MT-4 cells. However, 5f and 5j–5q exhibited some inhibitory activity against both types with EC50 values (>11.50 − >13.00 µg/mL). These results suggest that the structural modifications of these compounds might lead to the development of new antiviral agents. The quantum structure-activity relationship of these novel structural congeners is discussed.

Binuclear (salen)osmium phosphinidine and phosphiniminato complexes

The preparation of a number of binuclear (salen)osmium phosphinidine and phosphiniminato complexes using various strategies are described. Treatment of [Os(VI)(N)(L(1))(sol)](X) (sol = H(2)O or MeOH) with PPh(3) affords an osmium(IV) phosphinidine complex [Os(IV){N(H)PPh(3)}(L(1))(OMe)](X) (X = PF(6)1a, ClO(4)1b). If the reaction is carried out in CH(2)Cl(2) in the presence of excess pyrazine the osmium(III) phosphinidine species [Os(III){N(H)PPh(3)}(L(1))(pz)](PF(6)) 2 can be generated. On the other hand, if the reaction is carried out in CH(2)Cl(2) in the presence of a small amount of H(2)O, a μ-oxo osmium(IV) phosphinidine complex is obtained, [(L(1)){PPh(3)N(H)}Os(IV)-O-Os(IV){N(H)PPh(3)}(L(1))](PF(6))(2)3. Furthermore, if the reaction of [Os(VI)(N)(L(1))(OH(2))]PF(6) with PPh(3) is done in the presence of 2, the μ-pyrazine species, [(L(1)){PPh(3)N(H)}Os(III)-pz-Os(III){N(H)PPh(3)}(L(1))](PF(6))(2)4 can be isolated. Novel binuclear osmium(IV) complexes can be prepared by the use of a diphosphine ligand to attack two Os(VI)≡N. Reaction of [Os(VI)(N)(L(1))(OH(2))](PF(6)) with PPh(2)-C≡C-PPh(2) or PPh(2)-(CH(2))(3)-PPh(2) in MeOH affords the binuclear complexes [(MeO)(L(1))Os(IV){N(H)PPh(2)-R-PPh(2)N(H)}Os(IV)(L(1))(OMe)](PF(6))(2) (R = C≡C 5, (CH(2))(3)6). Reaction of [Os(VI)(N)(L(2))Cl] with PPh(2)FcPPh(2) generates a novel trimetallic complex, [Cl(L(2))Os(IV){NPPh(2)-Fc-PPh(2)N}Os(IV)(L(2))Cl] 7. The structures of 1b, 2, 3, 4, 5 and 7 have been determined by X-ray crystallography.

Robust motifs in 2-phenylethylammonium and related tetrahalometallates

The novel crystal structures of seven compounds which combine 2-phenylethylammonium cations and perhalometallate anions, all with the general formula (C8H9NH3+)2 MX42−, were determined to establish the effect of metal atom and halogen ligand substitution on the structures and hydrogen bonding interactions. Five of the structures, bis(2-phenylethylammonium) tetrachlorozincate, (C8H9NH3+)2 ZnCl42−, bis(2-phenylethylammonium) tetraiodozincate, (C8H9NH3+)2 ZnI42−, bis(2-phenylethylammonium) tetrabromodichloroiodozincate, (C8H9NH3+)2 ZnCl2BrI2−, bis(2-phenylethylammonium) tetrabromocadmate, (C8H9NH3+)2 CdBr42−, and bis(2-phenylethylammonium) tetrabromomercurate, (C8H9NH3+)2 HgBr42−, were found to be isostructural, while two of the compounds containing iodo ligands, bis(2-phenylethylammonium) tetraiodocadmate, (C8H9NH3+)2 CdI42−, and bis(2-phenylethylammonium) tetraiodomercurate, (C8H9NH3+)2 HgI42−, crystallize in a different, but related disordered structure. Strong N+–H⋯X−–M hydrogen bonding interactions, as well as weaker C–H⋯π aromatic interactions occur in all seven structures, and two robust tetrameric hydrogen bonded zero-dimensional motifs are present in all seven structures. C–H⋯Cl–M hydrogen bonding interactions are present in the structure of bis(2-phenylethylammonium) tetrachlorozincate, and result in the distortion of the geometry of the 2-phenylethylammonium cation. Comparison of the identified zero-dimensional hydrogen bonding motifs with those occurring in related structures reported in the literature shows that the motifs are robust and can tolerate changes in cation, metal and ligand to a large extent.

Structural characterization and catalytic properties of bis(1,1,3,3-tetramethylguanidinium) dichromate

The structure of bis(1,1,3,3-tetramethylguanidinium) dichromate was determined from powder X-ray diffraction data. The compound crystallizes in the monoclinic system (space group P21/n) with a=10.79714 (15)Å, b=11.75844 (16)Å, c=8.15097 (11)Å, β=109.5248 (6)°. The structure consists of dichromate anions (Cr2O72−) stabilized by tetramethylguanidinium cations ([H2NC(N(CH3)2)2]+ or [TMGH]+). Phase transitions of [TMGH]2Cr2O7 were determined by differential scanning calorimetry, thermal gravimetric analysis and in situ Raman spectroscopy, where the decomposition of the matrix into CrOx was found at 171–172°C. Further heat treatment to above 400°C resulted in formation of the thermodynamically stable Cr2O3, most likely with the [TMGH]+ cation as reductant. The catalytic activity of [TMGH]2Cr2O7 supported on TiO2 anatase in the selective catalytic reduction (SCR) of nitrogen oxide was also investigated, however only moderate activity was observed in the temperature range 100–400°C compared to the activity of e.g., vanadia supported on titania.

Structures of bis(1-methyltetrazole-5-thiolato)(tetranitrosyl)diiron and its intermediates in solutions

Single crystals of an iron complex with 1-methyltetrazole-5-thiol of the formula [Fe2(SC2H3N4)2(NO)4] (I) were obtained and examined by X-ray diffraction. According to electrochemical data, tetranitrosyl binuclear complex I rapidly decomposes in protic solvents with elimination of NO. The maximum amount of NO generated by complex I in 1% aqueous DMSO is ∼900 nmol. This amount is reduced by half 15 min after the beginning of the decomposition under anaerobic conditions. The dinitrosyl mononuclear intermediates [Fe(SC2H3N4)2(NO)]− and [Fe(SC2H3N4)2(NO)2]− were detected in solutions and identified by EPR spectroscopy and mass spectrometry. The low number of spins per complex in solutions indicates that the mononuclear complexes undergo further decomposition into NO and the species [Fe(SC2H3N4)3]−, [SC2H3N4]−, and [Fe4S3(NO)7]−. Complex I was found to be substantially more stable in DMSO than in methanol and 1% aqueous DMSO.

Nickel N‐heterocyclic carbene complexes in the vinyl polymerization of norbornene

AbstractVinyl polymerized norbornene has some useful properties such as good mechanical strength, optical transparency and heat resistance. Several transition metal complexes have been described in the literature as active catalysts for the vinyl polymerization of norbornene. We now report the use of three types of nickel(II) complexes with N‐heterocyclic carbene (NHC) ligands in the catalytic vinyl polymerization of norbornene under a range of conditions. Specifically, two nickel complexes bearing a chelating bis(NHC) ligand, two nickel complexes bearing two chelating anionic N‐donor functionalized NHC ligands as well as one diiodidonickel(II) complex with two monodentate NHC ligands were tested. The solid‐state structure of bis(1,3‐dimethylimidazol‐2‐ylidene)diiodidonickel(II), as determined by X‐ray crystallography, is presented. The highest polymerization activity of 2.6 × 107 g (mol cat)−1 h−1 was observed using the latter nickel complex as catalyst, activated by methylaluminoxane. The norbornene polymers thus obtained are of high molecular weight but with rather low polydispersity. Copyright © 2010 John Wiley & Sons, Ltd.

ChemInform Abstract: First Preparation of a Sulfurane with Four Carbon-Sulfur Bonds: Synthesis and Molecular Structure of Bis(2,2′-biphenylylene)sulfurane.

The first stable pentacoordinated sulfur compound with four carbon–sulfur bonds, bis(2,2′-biphenylylene)sulfurane 1, is prepared and its molecular structure is determined by X-ray crystallographic analysis.

Synthesis and crystal structures of bis(cyclopentyl)gallium phenoxide dimer and bis(cyclopentyl)gallium naphthoxide dimer

Tricyclopentylgallium reacted with phenol, naphthol respectively to yield phenoxide (or naphthoxide) of biscyclopentylgallium which have been characterized by elemental analysis, 1R, 1H NMR and mass spectrometry. X-ray diffraction analysis of compound 1 indicated that it belongs to the monoclinic system, space groups P21/c, with cell constants a=9.602(3), b=14.365(7), c=11.256(4)A, and β=97.54(3), Z=2(dimers), R=0.0706. Compound 2 assigned to the triclinic system, space groups P with cell constants a=9.392(4), b=9.928(7), c=11.263(7) A, a=112.48(5), β=104.74(4), γ=99.95(5), and Z=1(dimers), R=0.0526. The molecule of 1 or 2 contains an oxygen-bridged coplanar Ga2O2 four-membered ring respectively.

ChemInform Abstract: Molecular Geometry of Bis(N-chloromethyl)nitramine from Gas Electron Diffraction.

Abstract The molecular structure of bis ( N -chloromethyl) nitramine has been determined by gas electron diffraction. The bond lengths ( r g ), bond angles and angles of torsion (φ) with estimated total errors in parentheses are as follows: NO 1.216(3) A NN 1.422(5) A CN 1.443(4) A ClC 1.803(4) A CH 1.109(9) A ONO 128.0(14)° CNN 116.3(4)° CNC 124.8(9)° ClCN 111.6(5)° HCN 110.3(9)° φ CN 78.9(7)° φ NN 2.6(15)° The amine nitrogen has an essentially planar bond geometry. This molecule has practically C 2 symmetry. The two ClC bonds point to opposite sides of the planar C 2 NNO 2 skeleton.

‘Melen complexes’: a new family of Schiff base metal chelates derived from di-Meldrum’s acid derivatives

A new family of N 2O 2-tetradentate ligands and complexes derived thereof, based on Meldrum’s acid and diamines, has been developed. The structure of 7b has been unequivocally established by an X-ray crystallographic study. The general strategy has been successfully applied to the synthesis of a tridentate ligand that when reacted with Et 2Zn resulted in the formation of a coordinatively linked dimer.