Structural characterization and photophysical properties of a luminescent trinuclear zinc(II) complex exhibiting multiple coordination geometries

A luminescent trinuclear zinc(II) complex, tris(-2,3-toluenedithiolato)-1:2²S¹;1:2²S¹, 2:3²S²;3S², 1:3²S³;3S³-bis(2,2-bypyridine)-1²N,N,2²N,N-trizinc, containing 3,4-dimercaptotoluene (tdt) and 2,2-bipyridine (bpy) has been synthesized and found to have the trinuclear formulation Zn₃(tdt)₃(bpy)₂ (I). The complex crystallizes in the monoclinic space group P2₁/n with a = 11.7247(12), b = 20.134(2), c = 17.7376(18) Å and = 103.743(2). The complex has two heteroleptic zinc(II) centers exhibiting similar distorted trigonal bipyramidal geometries with the third homoleptic zinc(II) center displaying a flattened tetrahedral geometry. Present in the solid state are both intra- and intermolecular – interactions. The complex is emissive at 77 K in the solid state with an emission maximum at 574± 2 nm with a luminescence lifetime of 7.4± 0.4 ns. The unstructured emission is assigned as a metal-mediated ligand-to-ligand –^* charge transfer transition.     

Conformations of barbiturates related to pentobarbitone. IV. Crystal structure of 5-ethyl,5-(1′,3′-dimethylbut-2′-enyl) barbituric acid

Crystals of 5-ethyl,5-(1,3-dimethylbut-2-enyl) barbituric acid (13M2B), mp 139°C, are triclinic, space groupP¯1,Z=2, witha=8.134(2),b=9.210(2),c=9.265(2),=91.91(1),=105.66(2), and =96.83(2)°. The structure was solved by direct methods, and refined by least-squares procedures to giveR=0.065 for 2056 observed diffraction data. The 5-ethyl and the 1,3-dimethylbut-2-enyl groups are both directed over the plane of the barbiturate ring. It is suggested that the conformation of the latter is stabilized by interactions between the isobutenyl group and the delocalized system of the ring.     

Anticancer agent development. 5. X-ray structure and1H nmr spectral analysis of (1α,2α,5α,6α)-2,6-bis(3,4-methylenedioxyphenyl)-3,7-dioxabicyclo[3.3.0]octane-4,8-dione

The title compound, C₂₀H₁₄O₈, Mr=382.3, crystallized from chloroform in the centric space group P¯1 witha=6.516(4),b=6.798(3),c=9.545(7) Å,=85.31(5),=73.87(5), =79.59(4)°,V=399.2 ų, and D_calc=1.59 g cm^–3 forZ=1. Least-squares refinement of 1035 observed [F_o5(F_o)] reflections led to the final agreement index ofR=0.074. The molecule resides on a crystallographic center of inversion and is disordered into two different conformations. This manifests itself as a 50/50 disorder at O(4), C(2), and C(3). The observed structure reveals acis relationship between the bridgehead hydrogen atoms and the aryl rings. The 90 MHz¹H nmr spectrum of the title compound exhibits an AAXX spin system with a H(1)C(2) to H(1)C(3) and H(1)C(2) to H(1)C(3) coupling constant of 2.8 Hz. Computer spectral simulation and Karplus equation analysis are utilized to illustrate a relaxation of the torsion angles between H(1)C(2) and H(1)C(3), and H(1)C(2) and H(1)C(3) is solution.     

3,3′-di[1,3-thiazolidin-4-one] system. Structural and conformational studies on configurational isomers with anti-inflammatory activity

3,3(1,2-Ethanediyl)bis(2-halophenyl-thiazolidin-4-one) derivatives display different pharmacological activities depending on the configuration of the 2,2 centers and on the oxidation state of the sulfur atoms. Quantum-chemical calculations on the 3-fluorophenyl-substituted configurational isomers are reported here, together with the X-ray structure of the 11 dioxide derivative. This crystallizes in the monoclinic space group P2₁/c, with four molecules per unit cell and cell dimensions:a=18.917(3),b=9.003(2),c=12.062(2)Å, =96.20(3)°. The compound, which has an approximate center of symmetry in the middle of the ethylene chain and two asymmetric carbon atoms of opposite chiralities, is the (2R,2S-meso) (or 2S,2R-meso) stereoisomer.     

X-ray structures of two methoxybenzo[b]thiophenes

The crystal and molecular structures of two methoxybenzo[b]thiophenes have been determined by three-dimensional, single-crystal X-ray diffractometry. Both 3-(4-hydroxy-3, 5-dimethoxybenzoyl)-2-(4-methoxyphenyl)-6-methoxybenzo[b]thiophene and 3-(2,6-dimethoxybenzoyl)-2-(4-methoxyphenyl)-6-methoxybenzo[b]thiophene (hereafter referred to asI andII, respectively) crystallize in the monoclinic centrosymmetric space groupP2₁/n (No. 14, C _2h ⁵ ) with four formula units-per cell witha=6.866(1),b=28.638(2),c=11.830(2) Å, and =105.52(1)° anda=9.328(1),b=7.977(1),c=29.650(4) Å, and =97.87(1)°, respectively. The phase problems were solved by direct methods and the respective final full-matrix least-squares refinements converged toR=0.046 and 0.031. The structures differ in the positioning of the dimethoxy groups of the benzoyl ligands and the addition of a hydroxyl group inI. The molecules in the crystal lattice are held together by van der Waals forces plus the addition of hydrogen bonding in compoundI. Selected bond distances and angles and torsion angles are tabularized.     

Crystal structure of syn-1-acetyl-9′aH-8′- methoxyspiro[indole-3,2′-oxeto[3′,2′:4,5]furo[3,2-g][1] benzopyran]2,6′-dione

The crystal structure of syn-1-acetyl-9a-hydro-8-methoxyspiro[3H-indole-3,2(2aH) oxeto[3,2-g]furo[3,2-g]benzo[ b]pyran-2,6-dione 1 was determined by X-ray diffraction analysis. It possesses P2(1)/c space group symmetry, with a = 12.391(3), b = 15.035(3), c = 9.5435(19) Å, = 93.66(3), and D _calc. = 1.517 Mg/m³ for Z = 4.     

Hydrogen bonding in 2-hydroxy((di)thio)benzoates. I. X-ray structures of 2,6-dimethylpiperidinium salts

X-ray structural data are reported for 2,6-dimethyl-piperidinium-2-hydroxybenzoate (C₁₄H₂₁NO₃, orthorhombic,P2₁2₁,2₁, (19);a=7.983(1)Å,b=12.680(2)Å,c=13.838(2)Å;Z=4;R=0.042) and for two polymorphs of 2,6-dimethylpiperidinium-2-hydroxythiobenzoate (C₁₄H₂₁NO₂S), an-form (monoclinic,P2₁/n (14);a=8.005(4)Å,b=22.150(2)Å,c=8.672(4)Å,=101.91(6)°;Z=4;R=0.059) with an intramolecular O-HS hydrogen bond, and a-form (orthorhombic,P2₁2₁2₁ (19);a=8.188(1)Å,b=14.781(2)Å,c=24.163(4)Å;Z=8;R=0.15) with an intramolecular O-HO hydrogen bond. The intra-and intermolecular hydrogen bond patterns are discussed, including the literature data of 2,6-dimethylpiperidinium-2-hydroxydithiobenzoate.     

Structure of two 1,3-dioxane derivatives from 4′, 5′-dimethylfurocoumarins: 4a, 11a-dihydro-4a, 11a-dimethyl-8H-pyrano[3′,2′∶5,6]benzofuro[3,2-e]-1, 3-dioxan-8-one and 7a,11a-dihydro-7a,11a-dimethyl-2H-pyrano[2′, 3′∶4,5]benzofuro[3,2-d] (1,3) dioxan-2-one

Treatment of dimethylated psoralen and angelicin in the 4, 5-position leads to the formation of 1,3-dioxane derivatives, resulting from the condensation of an 1,3-dioxane ring to the 4, 5-positions of the dihydrofurocoumarin moiety. The structures of these new compounds, 4a, 1 1a-dihydro-4a, 11a-dimethyl-8H-pyrano [3, 25,6]benzofuro[3,2-e]-1, 3-dioxan-8-one (C₁₅H₁₄O₅) (1) and 7a, 11a-dihydro-7a, 11a-dimethyl-2H-pyrano[2, 34, 5]benzofuro[3, 2-d](1, 3)dioxan-2-one (C₁₅H₁₄O₅) (2) have been assigned by¹H and¹³C NMR measurements, mass spectrometry results, and X-ray analysis. Compound (1): triclinic,P¯1,a=9.847(2),b=8.927(2),c=8.334(2) Å,=95.98(2),=108.81(3), =106.73(3)°; compound (2): triclinic,P¯1,a=7.296(4),b=7.481(2),c=11.812(4) Å,=91.67(2),=95.97(4), =94.20(3)°. The structures were solved by direct methods and refined by full-matrix least squares toR=0.050 (1) and 0.056 (2). In both compounds the coumarin rings can be regarded as coplanar, while the five-membered ring adopts an envelope conformation and the 1,3-dioxane ring a chair conformation.     

Bis(2,6-(2′,6′-diisoproylanil)diformyl-4-chloro-phenolate) nickel(II)

Bis(2,6-(2,6-diisoproylanil)diformyl-4-chloro-phenolate) nickel(II) was prepared by the reaction of 2,6-(2,6-diisoproylanil)diformyl-4-chloro-phenol with nickel chloride. The title complex crystallized in P2₁/c, with cell dimensions a = 9.962(2) Å, b = 12.087(3) Å, c = 24.445(6) Å, and = 97.032(5), giving a volume of 2921.4(13) ų. The bis(2,6-(2,6-diisoproylanil)diformyl-4-chloro-phenolate) nickel(II) adapts an ideal parallelogram, in which the Ni atom is coordinated with two phenolic oxygen atoms [O(1), O(1A)] and two imino nitrogen atoms [N(1), N(1A)].     

The chemistry of the “insoluble red woods.” Part 15. The crystal structures of 7-benzyloxy-6,2′,3′,4′-tetramethoxy- and 2,6,7,2′,3′,4′-hexamethoxy-isoflav-3-ene

The reaction of 7-benzyloxy-6,2,3,4-tetramethoxyisoflavylium perchlorate with 1-(2,4-dimethoxyphenyl)-3-(3,4-dimethoxyphenyl)-prop-l-ene and of 6,7,2,3,4-pentamethoxyisoflavylium perchlorate with the same propene yielded respectively 7-benzyloxy-6,2,3,4-tetramethoxyisoflav-3-ene (5) and 2,6,7,2,3,4-hexamethoxyisoflav-3-ene (7) whose structures have been established by X-ray crystallography. Crystals of (5) are monoclinic, space groupP2₁/a (No. 14) with four molecules in a unit cell of dimensionsa=8.528(2),b=13.294(3),c=19.629(4) Å,=99.92(2)°. Crystals of (7) are also monoclinic, space groupC2/c (No. 15) with eight molecules in a unit cell of dimensionsa=28.088(3),b=10.662(3),c=12.869(1) Å,=97.32(1)°. Both structures were solved by direct methods and refined by full-matrix least-squares calculations to finalR values of 0.053 and 0.041 for 1673 and 1424 observed data for (5) and (7) respectively. The molecular dimensions are in accord with accepted values.For Part 14 see Whalley, W. B., Ferguson, G., and Khan, M. A., (1980)J. Chem. Res. (M), 2219.     

Conformations of barbiturates related to pentobarbitone. II. Crystal structure oftrans-5-ethyl-5-(1′,3′-dimethylbut-1′-enyl) barbituric acid

Crystals oftrans-5-ethyl-5-(1,3-dimethylbut-1-enyl) barbituric acid (13M1TB), mp 183° C, are triclinic witha = 7.677(2),b = 10.393(3),c = 9.176(3) Å, = 104.331(1), = 106.919(1), = 96.494(1)°, space group P, with two molecules in the unit cell. The structure was solved by direct methods and refined by least-squares procedures toR = 0.050 for 2809 observed diffraction maxima. The 5-ethyl group is oriented under the barbiturate ring with the orientation of the but-1-enyl group directed away from the ring. This orientation is determined by the 1-methyl substituent. The molecules are linked together by N-H ... O=C hydrogen bonds across inversion centers, thus forming single ribbons alongb. Adjacent ribbons are held together in theac plane by van der Waals interactions between alternating ethyl and l,3-dimethylbut-l-enyl groups.     

Crystal and molecular structure of 3-phenylisoxazolin-4,5-dione-4-[3′-phenyl-(2′H)Δ3′-isoxazolin-5′-on-4′-yl]hydrazone

The crystal and molecular structure of 3-phenylisoxazolin-4,5-dione-4-[3-phenyl-(2H)³-isoxazolin-5-on-4-yl]hydrazone, C₁₈H₁₂N₄O₄, has been determined from X-ray diffractometer data and refined by least-squares methods toR=0.047 for 1413 observed reflections. Crystals of C₁₈H₁₂N₄O₄ are monoclinic:a=13.76(1),b=11.11(1),c=14.10(1) Å, =90.5(1) °,Z=8, space groupC2/c.Among 11 possible tautomeric structures, this compound exhibits a hydrazono structure with intermolecular hydrogen bonds. The phenyl rings make angles of 9.03 ° and 35.12 ° with the planes of the isoxazole rings. Bond distances and angles have reasonable values, and extensive conjugation is evident within the molecule. Close molecular packing is given by layers of molecules approximately parallel to the (001) plane, and in each layer rows of molecules joined by hydrogen bonds run parallel to (¯110).     

A comparative study on structure and conformation of three hydroxybenzylamine ligands

Structure and conformation of three tridentate ligands are determined. All these three compounds crystallize in different space groups, the details are as follows: Bis[(3,5-dimethyl,2-hydroxy)-2-hydroxy-5-methoxy]benzylcyclohexylamine (DHBC): monoclinic I2/a (a = 17.691(1) Å, b = 9.707(1) Å, c = 24.235(2) Å, = 91.028(1)°); bis[(3,5-dimethyl,2-hydroxy)-2-hydroxy-5-bromo]benzylcyclohexylamine (DHBrBC): tetragonal P4₁2₁2 (a = b = 12.1138(1) Å, c = 28.485(1) Å) and bis[(3,5-dimethyl,2-hydroxy)-2-hydroxy-5-bromo]benzylmethylamine (DHBrBM): triclinic (a = 5.228(1), b = 12.364(1) Å, c = 13.234(1) Å, = 94.04(1)°, = 95.72(1),° = 95.90(1)°). The cyclohexane rings in DHBC and DHBrBC assume chair conformation. Both the phenyl rings are planar in all the molecules and orient at angles of 75.5(1)°, 62.2(1)°, and 53.9(2)°, respectively with each other. The bond angles around N atom show the sp³ character. Inter- and intramolecular O–HN and O–HO types of hydrogen bondings stabilize the molecules in the unit cell in addition to van der Waals forces.     

Crystal structures of 1-(2-hydroxyphenyl)-3-phenyl-1,3-propanedione and 1-(1,3-benzodioxol-5-yl)-3-(2,4-dimethoxyphenyl)-1,3-propanedione

1-(2-Hydroxyphenyl)-3-phenyl-1,3-propanedione crystallizes in the triclinic space group (a=5.4233(5),b=13.910(1),c=17.036(1) Å, =68.311(6), =80.854(7), =78.760(8)°) as two independent enolic tautomers in which the hydroxyl and phenolic protons are hydrogen bonded to the ketonic oxygen atom. The structure was refined toR=0.039 for 2085I3(I) reflections. 1-(1,3-Benzodioxol-5-yl)-3-(2,4-dimethoxyphenyl)-1,3-propanedione, which belongs to the triclinic space group (a=7.3990(7),b=8.1239(5),c=14.004(1) Å, =86.673(6). =88.574(7), =64.885(7)°) also exists in the enolic form. The structure was refined toR=0.040 for 1564I3(I) reflections.     

Characterization and structural analyses of trimethoxy and triethoxybenzo[b]thiophene

The crystal and molecular structures of two methoxybenzo [b] thiophenes have been determined by three-dimensional, single-crystal X-ray diffractometry. Both 3-(3,4,5-trimethoxybenzoyl)-2-(4-methoxyphenyl)-6-methoxybenzo[b]thiophene and 3-(3,4,5-triethoxybenzoyl)-2-(4-methoxyphenyl)-6-methoxybenzo[b]thiophene (hereafter referred to as I and II, respectively) crystallize in the triclinic centrosymmetric space group (No. 2, C¹) with two formula units per cell with a = 6.842(1) Å, b = 12.602(2) Å, c = 13.815(2) Å, = 94.80(1)°, = 98.27(2)°, and = 100.59(2)° and a = 10.600(1), b = 11.415(2), c = 12.137(2) Å, = 94.57(1)°, = 101.18(1)°, and = 110.45(1)°, respectively. The phase problems were solved by direct methods and the respective final full-matrix least-squares refinements converged to R = 0.039 and 0.068. The structures differ in the orientation of the trimethoxy and triethoxy groups of the benzoyl ligands. The molecules in the crystal lattice are held together by van der Waals forces. Selected bond distances, angles, and torsion angles are tabularized as well as reference to the synthesis of the title compounds and peripheral studies.     

Crystal and molecular structure of 1,1′,3,3′-tetraphenyloxaldiamidrazone

1,1,3,3-Tetraphenyloxaldiamidrazone, C₂₆H₂₄N₆, crystallizes in the monoclinic system: space groupP2₁/c,a= 13.946(1) Å,b= 5.706(1) Å,c= 17.109(1) Å, = 125.31(1) °,D _m = 1.254,D _c = 1.259 gcm^–3 andZ= 2. Intensities were obtained from –2 scans with a Syntex automated diffractometer using graphite-monochromated MoK radiation. The structure was solved by direct methods. Full-matrix least-squares refinement of all positional and thermal (anisotropic for the nonhydrogen atoms and isotropic for the hydrogen atoms) parameters using 2022 reflections [I>2(itI)] converged at a conventionalR of 0.041. The molecule is characterized by a conjugated pi system which includes the central N=C–C=N moiety and two of the four aniline groups. No intermolecular and only weak intramolecular hydrogen bonds are present.     

Two acetylamino derivatives of 2,4-bis(trichloromethyl)-1,3-benzdioxin showing different types of hydrogen bonding: (a) (C13C)CH⋯O=C and (b) N-H⋯O=C

8-Acetylamino-6-methyl-2,4-bis(trichloromethyl)-1,3-benzdioxin, (I), is monoclinic,P2₁/c,a=15.174(4),b=11.977(7),c=9.911(3)Å,=99.72(2)°. 6-Acetylamino-2,4-bis(trichloromethyl)-1,3-benzdioxin, (II), is monoclinic,P2₁/_n,a=5.927(4),b=40.623(1),c =7.120(3)Å,=91.39(4)°. In compound (I) the imino hydrogen atom is locked in an intramolecular hydrogen bond to the proximate oxygen atom of the heterocyclic ring and is not available for intermolecular hydrogen bonding. Instead the weakly acidic hydrogen atom [Cl₃C-C(2)]H takes part in a hydrogen bond to the carbonyl oxygen atom in another molecule. In compound (II) a normal intermolecular hydrogen bond of the type N-HO=C occurs. The 6-acetylam-ino group is twisted about the (C_Ar-N) bond such that the angles NHO=C, C_ArH_ArO=C, NHOH_ArC_Ar, at the carbonyl oxygen group total 360° (where NH is in the related molecule). The packing in both compounds takes the form of infinite chains and in compound (II) partial overlap of the aromatic ring and the acetylamino group, with very little offset, also occurs.     

X-ray structure determination of cyclobutane photodimers from (Z)-α, β-diarylacrylonitriles

Irradiation of(Z)-, -diarylacrylonitriles (1) ArCH=C(CN)Ar (a: Ar=2-thienyl, Ar=Ph;b: Ar=p-MeC₆H₄, Ar=Ph) in the solid state gives cyclobutane dimers (2) in good yield. The mass spectra of the dimers, where no fragments derived from dimers with equal groups on adjacent carbons are present, suggest a truxillic structure (head to tail dimerization). X-Ray determinations confirm a centrosymmetric arrangement with a D_2d symmetry of the cyclobutane ring and a puckering constant=24.0° for (2a) significantly higher than that of (2b) (=19.2°).     

Structure of 2,2′-anhydro-3′-O-acetyl-2′thio-1-β-D-arabinofuranosylcytosine hydrochloride1

2,2-Anhydro-3-O-acetyl-2-thio-1--D-arabinofuranosylcytosine hydrochloride crystallizes in space group P2₁2₁2₁ witha=10.373(1),b=14.517(2),c=9.496(1) Å. Reflections were measured on a diffractometer and the structure was solved by direct methods. Least-squares refinement converged atR=0.056 andR _w =0.063. The study of this crystal structure showed that the alterations in the geometry of 2,2-anhydro-1--D-arabinofuranosylcytosine when the bridge oxygen is replaced by sulfur are localized in the region of the fused ring. The angle at the bridge atom decreases to nearly 90°, with concomitant enlargements of about 5°–7° in the angles opposite to the bridge atom. Angle C(1)-N(1)-C(6) decreases by 4°. Also, the amount of double bond character in the bond formed by C(2) and the bridge atom decreases. A survey of the conformational features of S,2-cyclonucleosides and comparison with O,2-cyclonucleosidcs showed that their preferred conformations are the same. However, S,2-cyclonucleosides exhibit a wider range of P and values. This correlates with a greater ease of the sulfur containing five-membered ring to pucker as compared to the oxygen-cyclo ring.This paper is part of the authors' dissertation (Vitali, 1986).     

Hydrogen-bond networks in the mono- and diprotonated cyclic diamine [9]aneN2S

The hydrogen-bond networks in the mono- and diprotonated cyclic diamine, 1-thia-4,7-diazacyclononane, [9]aneN₂S, have been examined. Crystals of the monoprotonated, form [9]aneN₂S HCl, contain a ribbon-like network of alternating strong and weak intermolecular N H Cl hydrogen bonds and weak intramolecular N H N hydrogen bonds. Crystal data for [9]aneN₂S HCl: monoclinic, a = 6.6640(6) Å, b = 10.3493(9) Å, c = 6.9807(6) Å, = 108.847(1)°, V = 455.63(7) ų, space group P2₁, Z = 2. In the di-protonated form, [9]aneN₂S 2HBr, the ribbon-like network comprises strong intermolecular and weak intramolecular N H Br hydrogen bonds. Crystal data for [9]aneN₂S 2HBr: orthorhombic, a = 12.5918(13) Å, b = 8.0753(9) Å, c = 10.6856(11) Å, V = 1086.5(2) ų, space group Pnma, Z = 4. The chloride anions of [9]aneN₂S HCl align in interlocking columns in the a- and c-direction whereas the bromide anions in [9]aneN₂S 2HBr occupy channels in the b-direction.