μ₂-m-Xylylenebis(salicylaldiminato)-bis­(η⁴-1,5-cyclo­octa­diene)dirhodium(I) dichloro­methane solvate

In the title solvate, [Rh₂(C₂₂H₁₈N₂O₂)(C₈H₁₂)₂]·CH₂Cl₂, each organometallic mol­ecule is composed of two Rh^I cations, the tetra­dentate dianion α,α′-bis­(salicylaldiminato)-m-xylene and two 1,5-cyclo­octa­diene (COD) ligands. Each Rh^I atom is coordinated by one O atom [Rh—O = 2.044 (2) and 2.026 (2) Å], one N atom [Rh—N = 2.083 (2) and 2.090 (2) Å], and one COD ligand via two η²-bonds, each directed toward the mid-point of a C=C bond (Cg): Rh—Cg = 2.007 (2), 2.013 (2), 2.000 (2) and 2.021 (2) Å. Each Rh^I atom has a quasi-square-planar coordination geometry, with average r.m.s. deviations of 0.159 (1) and 0.204 (1) Å from the mean planes defined by Rh and the termini of its four coordinating bonds. The two COD ligands have quasi-C₂ symmetry, twisted from ideal C_2v symmetry by 30.0 (3) and −33.1 (3)°, and are quasi-enanti­omers of one another. The intra­molecular Rh...Rh distance of 5.9432 (3) Å suggests that there is no direct metal–metal inter­action.

Bis[2,3,4-trimethyl-5-[(3,4,5-trimethyl-2H-pyrrol-2-yl­idene-κN)meth­yl]-1H-pyrrolato-κN]copper(II)

In the title complex, [Cu(C₁₅H₁₉N₂)₂] or [Cu(L₂)] (HL is 3,3′,4,4′,5,5′-hexa­methyl­pyrromethene), the Cu^II atom is coordinated by four N atoms [Cu—N 1.939 (2)–1.976 (2) Å] from two L ligands in a distorted tetra­hedral geometry. The mean planes of the CuN₂C₃ metallocyclic rings form a dihedral angle of 72.73 (6)°. In the L ligands, the pyrrole rings are inclined to each other at dihedral angles of 3.03 (7) and 9.83 (7)°. The crystal packing exhibits weak inter­molecular C—H...π inter­actions, which form chains in [100].

Di-μ-carbonyl-bis­[bis­(triphenyl­phos­phane)rhodium(0)](Rh—Rh) acetone disolvate

The dirhodium complex, [Rh₂(C₁₈H₁₅P)₄(CO)₂]·2(CH₃)₂CO, has crystallographic twofold symmetry and the Rh—Rh distance is 2.6266 (8) Å. The four atoms proximate to each Rh atom [Rh—P = 2.3222 (7) and 2.3283 (8) Å, and Rh—C = 1.961 (3) and 2.045 (3) Å] form a distorted tetra­hedron with large deviations from the putative tetra­hedral angles [r.m.s. deviation = 23 (1)°]. The six angles more closely approximate those of a trigonal bipyramid [r.m.s. deviation = 14 (1)°] with one missing equatorial ligand. The two bridging carbonyl ligands are much more linearly coordinated to one Rh [Rh—C[triple bond]O = 151.0 (2)°] than to the other [127.0 (2)°], and the two Rh₂CO planes form a dihedral angle of 45.43 (5)°. The two acetone solvent mol­ecules are disordered, and their estimated scattering contribution was subtracted from the observed diffraction data using the SQUEEZE routine in PLATON [Spek (2009). Acta Cryst. D65, 148–155].

(E)-3,3′,4,4′,7,7′,8,8′-Octa­methyl-2H,2′H-1,1′-bi(cyclo­penta­[fg]acenaphthyl­enyl­idene)-2,2′,5,5′,6,6′-hexa­one dichloro­methane monosolvate

The title compound, C₃₆H₂₄O₆·CH₂Cl₂, is a dimer of two essentially planar (r.m.s., deviations of fitted plane of 14 pyracene C atoms = 0.0539 and 0.0543 Å) tetra­cyclic pyracene frameworks (each with four methyl groups and three carbonyl groups on the peripheral carbon atoms) twisted along a central C=C bond with an angle of 50.78 (3)° at 90 K. There are notably long Csp²—Csp² bonds associated with the carbonyl groups, the longest being 1.601 (3) Å between two carbonyl C atoms. There are also intermolecular carbonyl...carbonyl interactions of both parallel and antiparallel types, with C...O distances in the range 3.041 (3) to 3.431 (2) Å. This compound is of inter­est with respect to the synthesis of fullerene fragments, such as corannulene and semibuckminsterfullerene derivatives (or `buckybowls'), and is a side product of the previously reported oxidation reaction. Structural details, such as planarity analysis of fused rings, out-of-plane deviation of substituents, inter­molecular inter­actions, and longer than typical bond lengths, will be discussed as well as comparisons to structurally related compounds.

25,26-Bis(propan-2-yl­idene)hepta­cyclo[20.2.1.1^10,13.0^2,21.0^3,8.0^9,14.0^15,20]hexa­cosa-2(21),3,5,7,9(14),11,15,17,19,23-deca­ene

In the title compound, C₃₂H₂₈, the central cyclo­octa­tetra­ene ring has a boat conformation, and the mol­ecule is saddle shaped. The seat is defined by the mean plane of the four-atom attachment points (r.m.s. deviation = 0.014 Å) of the two bicyclo­heptenyl substituents. These substituents comprise the pommel and cantle, with each mean plane defined by four atoms proximate to the seat (r.m.s. deviations = 0.002 and 0.004 Å). Relative to the seat, the pommel and cantle bend up 31.16 (4) and 29.40 (5)°, while the benzo units (flaps, r.m.s. deviations = 0.006 and 0.009 Å) bend down 36.75 (4) and 38.46 (4)°. The mean planes of the dimethyl­ethyl­idene units are almost perpendicular to the saddle seat, making dihedral angles 86.89 (4) and 88.01 (4)°.

(2R,4R)-4-(2-Eth­oxy-2-oxoeth­yl)-2,6,6-trimeth­yl–2-oxo-1,3,6,2λ⁵-dioxaza­phospho­can-6-ium iodide

The title compound, C₁₁H₂₃NO₅P⁺·I⁻, consists of an eight-membered cationic heterocyclic ring in a boat–chair conformation. The ring features a tetra­alkyl­ammonium N and a methyl­phospho­nate P atom. A –CH₂(CO)OC₂H₅ ester side chain at the C adjacent to oxygen produces two chiral centers at that substituted C atom and the P atom, both of which were determined to have absolute R,R configurations. A previously determined racemic bromide analog has exactly the same ring but with a –C₁₅H₃₁ side chain. In that structure, both chiral centers show the same relative R/S,R/S configurations, but the ring in the bromide analog is in a boat conformation.

syn-5,10,15-Tris(dichloro­meth­yl)-5,10,15-trihy­droxy-5H-diindeno­[1,2-a:1',2'-c]fluorene dichloro­methane 0.82-solvate

The title compound, C₃₀H₁₈Cl₆O₃·0.82CH₂Cl₂, consists of a slightly cup-shaped seven-ring truxene nucleus with hy­droxy and dichloro­methyl substituents at stereocenters 5R/S, 10R/S and 15R/S. C-Cl distances are in the range 1.759 (4)-1.783 (3) Å. Solvent channels parallel to the b axis appear to be partially occupied by highly disordered dichloro­methane solvent mol­ecules, the contribution of which were removed from the refinement with the SQUEEZE procedure in PLATON [Spek (2009). Acta Cryst. D65, 148-155]. Only one of the OH groups forms a hydrogen bond, which is inter­molecular to another OH group, forming centrosymmetric dimers in the crystal.

1-(Adamantan-1-yl)-3-(4-meth­oxy­phenyl)prop-2-en-1-one

The title mol­ecule, C₂₀H₂₄O₂, is a chalconoid derivative in which the keto–enone group is slightly distorted from planarity; the O=C—C=C torsion angle is 12.24 (13)°.

1,2,3,4,5,6,7,8,13,13,14,14-Dodeca­chloro-1,4,4a,4b,5,8,8a,12b-octa­hydro-1,4:5,8-dimethano­triphenyl­ene at 90 K

The previously reported room-temperature crystal structure [Jaud Baldy, Negrel, Poite & Chanon (1993). Z. Kristallogr. 204, 289–291] of the title compound, C₂₀H₈Cl₁₂, is monoclinic with Z′ = 1, whereas the 90 K structure reported herein is triclinic with Z′ = 2 and shows a 2% volume contraction. The crystallographically independent unit chosen consists of both enanti­omers (Λ and Δ) of this propeller-like mol­ecule. Both enanti­omers display quasi-twofold symmetry, with average bond-length/bond-angle deviations of 0.0018 (4) Å and 0.41 (2)° for Λ, and 0.0026 (4) Å and 0.50 (2)° for Δ.

(S)-2-Oxotetra­hydro­furan-3-aminium bromide

In the title HBr salt of (S)-homoserine lactone, C₄H₈NO₂⁺·Br⁻, the five-membered ring has an envelope conformation, with the –CH₂– C atom adjacent to the N-substituted C atom at the flap position. The four-atom mean plane (r.m.s. deviation = 0.005 Å) of the envelope forms a dihedral angle of 32.12 (9)° with the three-atom flap plane. The distorted square-pyramidal coordination about the anion involves five surrounding cations, with the square base defined by three N—H...Br hydrogen bonds [Br...N = 3.3046 (10), 3.3407 (12) and 3.3644 (13) Å] and near-contact with an H atom attached to C [Br...C = 3.739 (1) Å]. Another Br...C contact of 3.427 (1) Å defines the apex. There is also an N—H...O hydrogen bond present linking the cations.

Tetra­methyl anthracene-2,3,6,7-tetra­carboxyl­ate–tetra­methyl 9,10-dihydro-9,10-dioxoanthracene-2,3,6,7-tetra­carboxyl­ate (1/1)

In the title co-crystal, C₂₂H₁₆O₁₀·C₂₂H₁₈O₈, the independent tetra­methyl 9,10-dihydro-9,10-dioxoanthracene-2,3,6,7-tetra­carboxyl­ate, (I), and tetra­methyl anthracene-2,3,6,7-tetra­carboxyl­ate, (II), components occupy separate crystallographic inversion centers. In (II), the dihedral angles between the mean aromatic plane and the two independent carboxyl­ate planes are 41.32 (10) and −38.35 (10)°. The methyl­carboxyl­ate groups of (I) are disordered, with each resolvable into two groups. In the least disordered carboxyl­ate, the apparent angles between the mean aromatic plane and the two partial carboxyl­ate planes [site occupations = 0.510 (3) and 0.490 (3)] are 16.8 (3) and 23.3 (3)°. In the highly disordered group, the apparent angles between the mean aromatic plane and the two partial carboxyl­ate planes [site occupations = 0.510 (3) and 0.490 (3)] are 78.3 (3) and −74.1 (3)°. In addition, this extreme disorder leads to an artificially elongated C(aromatic)—C(carbox­yl) bond.

(1R,4R,5aS,7S,9aS)-7,9a-Dimethyl-6-methyl­ene-3-oxo-1,3,4,5,5a,6,7,8,9,9a-deca­hydro­naphtho­[1,2-c]furan-1,4-diyl diacetate

The title compound, C₁₉H₂₄O₆, is a sesquiterpene lactone isolated from the Kenyan plant Warburgia ugandensis. Ring A adopts a chair conformation, ring B is in a C₂ twist conformation and the lactone ring is nearly planar with maximum deviation 0.007 (1) Å. The reported absolute configuration is based on that of the similar compound bromo-parasiticolide A and is supported by analysis of Bijvoet differences from light atoms in Mo Kα radiation.

4-Nitro-1-[(trimethyl­sil­yl)ethyn­yl]benzene: low-temperature polymorph at 100 K

The title compound, C₁₁H₁₃NO₂Si, is a low-temperature form of the previously reported room-temperature structure [Garcia et al. (1998). Acta Cryst. C54, 489-491]. At 298 K, the material crystallizes in the space group Pnma and occupies a crystallographic mirror plane, but at 100 K the space group changes to P2₁2₁2₁, the volume decreases by 5% and the mol­ecule distorts. The greatest mol­ecular distortions from C_s symmetry are rotations of the trimethyl­silyl and nitro groups by 10.56 (8) and 11.47 (9)°, respectively, to the benzene mean plane. At low temperature, the crystal also becomes an inversion twin, the refined ratio of the twin components being 0.35 (15):0.65 (15).

Monoclinic polymorph of 2,5-dide­oxy-2,5-epithio-1,3:4,6-bis-O-[(R)-phenyl­methyl­ene]-L-iditol

The title compound C₂₀H₂₀O₄S, is polymorphic. In the tetra­gonal form, the mol­ecule lies on a crystallographic twofold axis, while the monoclinic form has only approximate C₂ mol­ecular symmetry. The greatest excursion from C₂ symmetry is in the orientation of the two phenyl rings; at 100 K, one of the rings is rotated -37.2 (3)° and the other by 46.9 (3)° from their symmetric (tetra­gonal) positions. There are only minor differences in the three-ring nucleus; the best mol­ecular fit of the tetra­gonal and monoclinic forms, both at 100 K and excluding phenyl rings and H atoms, shows an r.m.s. deviation of 0.066 Å. Both forms have the same absolute configuration.

Ortho­rhom­bic polymorph of (2E)-2-(2,3-dihydro-1H-inden-1-yl­idene)-2,3-di­hydro-1H-inden-1-one

The title compound, C₁₈H₁₄O, is polymorphic at 123 K. The ortho­rhom­bic form reported herein has two independent mol­ecules in the asymmetric unit, with mol­ecular volume 313.5 ų. The previously reported triclinic (P-1) form [Raston & Scott (2000). Green Chem., 2, 49–52] has mol­ecular volume 309.6 ų at the same temperature. All three mol­ecules deviate significantly and systematically from the putative C_s symmetry (δ_r.m.s. = 0.0265, 0.0256, 0.0497 Å). Comparison of the two molecules in the orthorhombic polymorph shows that 16 of the 19 equivalent pairs of framework atoms have a mirror-image pattern of deviations (above/below plane), suggesting that the two are quasi-enanti­omorphs. The pattern of deviations in the triclinic form is nearly the same (13 of 19 atom pairs) as the ortho­rhom­bic form.

2-Anilino-5,7-dimethyl­pyrazolo­[1,5-a]pyrimidine-3-carbonitrile

The title compound, C₁₅H₁₃N₅, crystallizes with two independent mol­ecules in the asymmetric unit. The mol­ecular conformations are stabilized by C—H...N contacts forming S(6) ring motifs. In the crystal, pairs of mol­ecules are connected into R₂²(12) dimers by N—H...N hydrogen bonds. C—H...π inter­actions and π–π stacking inter­actions [centroid–centroid distances = 3.6085 (8), 3.6657 (8), 3.4745 (8) and 3.5059 (8) Å] also also observed.

5-Amino-3-anilino-1H-pyrazole-4-carbonitrile

In the title compound, C₁₀H₉N₅, the phenyl ring is twisted with respect to the pyrazole ring, forming a dihedral angle of 24.00 (6)°. In the crystal, mol­ecules are linked by N—H...N hydrogen bonds into chains running parallel to [010] containing alternating R₂²(6) and R₂²(12) rings. Further inter­actions are found in the crystal, viz. N—H...π(phen­yl) inter­actions and weak face-to-face π–π stacking inter­actions [centroid–centroid distance = 3.8890 (6) Å] between the centroids of the pyrazole and phenyl rings are observed.

1,2-Bis{2-[2-(trimethyl­sil­yl)ethyn­yl]phen­yl}ethane-1,2-dione

The title compound, C₂₄H₂₆O₂Si₂, has C₂ crystallographic symmetry. The dihedral angle between the aromatic rings is 84.5 (2)°. The acetyl­ene group is slightly non-linear, with angles at the acetyl­ene C atoms of 175.7 (2) and 177.0 (2)°. In the crystal structure, only van de Waals interactions occur.

N-Acetyl-5-chloro-3-nitro-L-tyrosine ethyl ester

The title compound, C₁₃H₁₅ClN₂O₆, was synthesized by hypochlorous acid-mediated chlorination of N-acetyl-3-nitro-L-tyrosine ethyl ester. The OH group forms an intra­molecular O—H...O hydrogen bond to the nitro group and the N—H group forms an inter­molecular N—H...O hydrogen bonds to an amide O atom, linking the mol­ecules into chains along [100]. The crystal studied was a non-merohedral twin, with a 0.907 (4):0.093 (4) domain ratio.

N-[2-(Phenyl­sulfon­yl)eth­yl]benzyl­amine

The title compound, C₁₅H₁₇NO₂S, exhibits intra­molecular hydrogen bonding between the amine H atom and a sulfonyl O atom. The conformation of the mol­ecule is described by the four PhCH₂-NH-CH₂-CH₂-SO₂Ph torsion angles of 79.6 (2), -166.21 (14), -70.29 (17) and -58.93 (13)°.

2-(3,4-Dimeth­oxy­phen­yl)-4,5-diphenyl-1-(prop-2-en-1-yl)-1H-imidazole

In the title compound, C₂₆H₂₄N₂O₂, the planar 1H-imidazole ring makes dihedral angles of 35.78 (4), 26.35 (5) and 69.75 (5)°, respectively, with the dimeth­oxy­phenyl ring and the phenyl rings in the 4- and 5-positions. In the crystal, C—H...O hydrogen bonds connect neighbouring mol­ecules, forming infinite chains running along the b axis. Furthermore, the crystal structure exhibits a C—H-...π inter­action between a methyl H atom and a phenyl ring from an adjacent mol­ecule.

1-(2-Hy­droxy-5-meth­oxy­phen­yl)-3-methyl­but-2-en-1-one

The title compound, C₁₂H₁₄O₃, is a natural product derived from the medium-sized hawthorn Crataegus persimilis ('prunifolia'). The mean plane of the butene moiety is twisted by 13.27 (7)° with respect to the that of the dioxobenzaldehyde moiety. There is an intra­molecular hydrogen bond between the hydroxyl group and the carbonyl O atom.

(1E,2E)-1,2-Bis[(1-benzyloxymethyl-1H-indol-3-yl)methylidene]hydrazine

The title compound, C₃₄H₃₀N₄O₂, lies on an inversion center and consists of two 3-substituted-1H-indole units linked by a 1,2-dimethyl­enehydrazine bridge. It is one of numerous examples in which two aromatic ring systems are joined by this 4-atom bridge. The geometry of the centrosymmetric bridge is: C(arom)—C = 1.444 (3), C=N = 1.284 (3), N—N = 1.414 (4) Å, C(arom)—C=N = 122.6 (2) and C=N—N = 111.9 (2)°. The nine non-H atoms of the indole unit lie in a plane (δ_r.m.s. = 0.0089 Å) which is twisted 6.0 (2)° with respect to the hydrazine bridge plane. The benzyl­oxymethyl substituents do not lie in the plane of the rest of the mol­ecule and are in a folded rather than an extended conformation. This is described by the three torsion angles in the middle of the C=N—C—O—C_Bz group, viz. 98.5 (3), −62.1 (3), and −66.3 (2)°.

Redetermination and absolute configuration of (+)-7-epiclusianone

The absolute configuration of 3-benzoyl-4-hy­droxy-6,6-dimethyl-1,5,7-tris­(3-methyl­but-2-en­yl)bicyclo­[3.3.1]non-3-ene-2,9-dione, C₃₃H₄₂O₄, isolated from Hypericum hypericoides, has been determined. The previous study [Xiao et al. (2007). J. Nat. Prod. 70, 1779–1782] gave only the established relative configuration. The three stereogenic centers are now established as 1R, 5R and 7S on the basis of the refinement of the Flack absolute structure parameter against Cu Kα data and correspond to a specific rotation of [α]_D²⁰ = +66°. The enol–hy­droxy group forms an intra­molecular O—H...O hydrogen bond to close an S(6) ring.

5,7,8,10,11,13,14,16-Octa­hydro-6,15-(ethanoxyethanoxyethano)-1,4:17,20-dietheno[9,12,6,15]benzodioxadiaza­cyclo­docosine

The title compound, C₃₂H₄₀N₂O₄, is a 1,10-diaza-18-crown-6 cryptand with an o-terphenyl bridge. In the polyether ring, two adjacent –CH₂– groups are disordered with very nearly equal populations of two conformers. The ordered bond lengths are normal, with average C—C = 1.511 (3) Å, C—O = 1.421 (3) Å, and C—N = 1.466 (4) Å. The r.m.s. deviations of the three rings of the terphenyl bridge vary from 0.007 to 0.009 Å and the two rings ortho to one another are twisted by 50.75 (5) and 47.76 (4)° with respect to the third ring. The N...N distance is 5.408 (1) Å.