Pseudo-inversion Centre Research Articles

Tetramethyl biphenyl-3,5,3′,5′-tetracarboxylate benzene sesquisolvate

The title structure, C20H18O8.1.5C(6)H(6), is a tetrasubstituted biphenyl which has a pseudo-inversion centre between the two halves. The benzene solvent molecules lie in special positions, one with twofold rotation symmetry and two with inversion symmetry. The tetramethyl ester molecule is twisted and forms a supramolecular assembly of stacked sheets.

L-Methioninium nitrate

The asymmetric unit of the title compound, C5H12NO2S+·NO3−, is composed of two crystallographically independent me­thioninium cations related by pseudosymmetry (−x, 1 \over 5 + y, ½ − z) and two nitrate anions related by a pseudo-inversion centre at (0.50, 0.43, 0.25). In one of the residues, the straight side-chain conformation is gauche II–trans–gauche II, while in the other it is gauche II–trans–trans. In the crystal, the me­thioninium residues form N—H⋯O hydrogen-bonded molecular columns, which are interlinked by N—H⋯O and O—H⋯O hydrogen bonds involving the O atoms of the nitrate groups.

11-Methyl-12a-phenyl-9a,12a-dihydrophenanthro[9',10':5,6][1,4]dioxino[2,3-d]oxazole and 9a-(10-hydroxyphenanthren-9-yl)-11,12a-diphenyl-9a,12a-dihydrophenanthro[9',10':5,6][1,4]dioxino[2,3-d]oxazole.

In the title compounds, C(24)H(17)NO(3), (I), and C(43)H(27)NO(5), (II), the dioxine ring is not planar and tends toward a boat conformation. The oxazoline ring adopts a twisted conformation in molecule (I) but is essentially planar in molecule (II). The configuration of the dioxine-oxazoline system is determined by the sp(3) state of the two shared atoms. The phenanthrene moiety is nearly coplanar with the dioxine ring, while the phenyl ring is perpendicular to the attached oxazole ring. The triclinic unit cell of (II) contains two crystallographically independent molecules related by a pseudo-inversion centre.

2-Amino-5-(4-chlorophenyl)-1-methylimidazole

The asymmetric unit of the title compound, C10H10ClN3, contains four independent mol­ecules, two of which are related by a pseudo-inversion centre. Intermolecular N—H⋯N and N—H⋯Cl interactions are present in the crystal.

5-(4-Chlorophenyl)-3-oxa-4-azatricyclo[5.2.1.02,6]dec-4-ene

The asymmetric unit of the title compound, C14H14ClNO, contains two crystallographically independent mol­ecules related by a pseudo-inversion centre at (1.00, 0.65, 0.25). The isoxazoline rings of these two mol­ecules are planar and the structure analysis confirms the exo-orientation of the isoxazole ring to norbornane. The two mol­ecules in the asymmetric unit differ in the conformation of the chloro­phenyl rings.

DL-Phenylalaninium dihydrogen phosphate

In the title compound, C9H12NO2+·H2PO4−, the racemate has crystallizes in a non-centrosymmetric space group, Pc. However, both the phenyl­alaninium and di­hydrogen phosphate residues are related by a pseudo-inversion center at about (0.5, 0.25, 0.25). Each phosphate anion forms a strong O—H⋯O hydrogen bond with a phenyl­alaninium residue. The aggregation of the hydro­philic zone is in a layer parallel to (010) at x = 0, and the hydro­phobic zone is sandwiched between two such layers at x = 0 and x = 1.

(Z)-3-Acetonylidene-2,3-dihydro-1H-isoindolin-1-one

The asymmetric unit of the title compound, C11H9NO2, contains two mol­ecules which are related by a pseudo-inversion centre and form an N—H⋯O hydrogen-bonded dimer. The least-squares planes through the non-H atoms of the mol­ecules illustrate the overall molecular planarity. The mol­ecules assume Z configurations about the exocyclic C=C bond. In the crystal, intermolecular hydrogen bonds link the mol­ecules into infinite chains.

Dimethyl (1R,8R)-1,11,11-trimethyl-2,3-diazatricyclo[6.2.1.0(2,6)]undeca-3,5-diene-4,5-dicarboxylate, a chiral molecule with an approximate centrosymmetric crystal structure.

The crystal structure of the title compound, C16H22N2O4, has two independent chiral mol­ecules related by a pseudo-inversion centre. 14 of the 22 non-H atoms have a centrosymmetric counterpart within a tolerance of 0.17 Å. A search of the Cambridge Structural Database [Spring 2000; Allen & Kennard (1993). Chem. Des. Autom. News, 8, 1, 31–37] shows at least 10% of the crystal structures reported in the literature with space group P21 and Z = 4 to be chiral compounds with a pseudo-P21/c packing.

Tetraallyl (2,2′-bipyridyl)-rac-3,3,7,7-tetramethyl-trans-5-palladatricyclo[4.1.0.02,4]heptane-1,2,4,6-tetracarboxylate above and below the phase-transition temperature of 194 K

The crystal structure of the title compound, (2,2′-bipyridyl-κ2N,N′)(tetra­allyl 3,3,3′,3′-tetra­methyl-1,1′-bi­cyclo­propane-1,1′,2,2′-tetra­carboxyl­ato-κ2C2,C2′)­palladium(II), [Pd(C26H32­O8)(C10­H8­N2)], is disordered above 194 K. A doubling of the unit cell is observed on cooling. The structure at 143 K contains two ordered mol­ecules related by a pseudo-translation vector of approximately (0.44,0.00,0.50) or a pseudo-inversion center at approximately (0.22,0.00,0.25). Weak intermolecular C—H⋯O interactions are enhanced in the low-temperature structure.

N-(4-cyanophenyl)-alpha-(4-methoxyphenyl)nitrone

In the crystal structure of the title compound, 4-cyano-N-(4-methoxy­benzyl­idene)­phenyl­amine N-oxide, C15H12N2O2, the 4-methoxy­phenyl is approximately coplanar with the nitrone moiety but significantly rotated with respect to the 4-cyano­phenyl moiety. The extent of this rotation is significantly different for the two crystallographically independent mol­ecules of the asymmetric unit [dihedral angles of 19.4 (1) and 26.5 (1)°]. The geometry about the C=N bond is Z. The two mol­ecules are related to one another by a pseudo inversion centre.

Crystal structure and emission study of [(PPh3)2Cu(dmp)-O-(dmp)Cu(PPh3)2]2+ (dmp = 2,9-dimethyl-1,10-phenanthroline)

The synthesis and crystal structure of a luminescent dinuclear Cu(I) complex as the BF− 4 salt from toluene and methanol containing triphenylphosphine and μ-oxo-bis(2,9-dimethyl-1,10-phenanthroline) is described. The coordination geometry about the Cu(I) center is distorted tetrahedral. An unusual feature of the structure is a pseudo-inversion center located near the oxygen atom at approximately 0.51, 0.26, 0.25, such that all of the atoms except for the oxygen are related by a pseudo-inversion center to another atom in the same molecule, as well as by crystallographic inversion to the other molecule in the unit cell. The complex displays luminescence from an MLCT band in fluid solution and emission from both a metal-centered charge-transfer and intraligand (phenanthroline) state at 77K in a chloroform snow. Crystal data: triclinic, P $$\bar 1$$ , a = 15.163(2), b = 16.985(2), c = 18.731(2) A, α = 106.458(9), β = 91.416(8), γ = 102.557(9)°, V = 4496(1) A3, and Z = 2.

3,4-Bis(1-adamantyl)-1,2-dithiete: the first structurally characterized dithiete unsupported by a ring or benzenoid frame.

The structure determination of 3,4-bis(1-adamantyl)-1,2-dithiete, (C10H15)2C2S2 or C22H30S2, reported herein is the first crystallographic characterization of a 1,2-dithiete molecule unsupported by a benzenoid frame. Two independent molecules exist in the asymmetric unit separated by a pseudo-inversion center. The S2C2 four-membered dithiete ring is planar, with a trapezoidal shape enforced by the longer disulfide bond [average 2.086 (2) A] compared with the olefinic bond [average 1.363 (6) A]. The adamantyl substituents differ from one another by adopting slightly different rotational conformations with respect to the dithiete ring. The quaternary C atoms of the adamantyl groups deviate only slightly from the plane of the dithiete ring (average displacement of 0.023 A).

First Determination of the Absolute Configuration of an Atropisomeric Flavin Derivative

The crystal structure and absolute configuration of the (-)-enantiomer of 3-(4,6-dibromo-2-methylphenyl)-10-(4-tert-butylphenyl)pyrimido[4,5-b]quinoline-2,4(3H,10H)-dione methanol solvate, C28H23Br2N3O2.CH4O, have been determined. The absolute configuration is S. The asymmetric unit contains two crystallographically independent molecules which are related by a pseudo inversion center.

A Hydrated Schiff Base Derivative of Bis(acetylacetone)ethylenediimine with 2-Pyridinylethyl Side Chains

3,10-Bis[2-(2-pyridinyl)ethyl]-4,9-dimethyl-5,8-diazadodeca-4,8-diene-2,11-dione tetrahydrate, C 26 H 34 N 4 O 2. 4H 2 O, exists as a keto-amine tautomer, i.e. the 3,9-diene. There are two independent molecules in the triclinic unit cell, each located on a crystallographic inversion center. The orientation of the pyridine rings creates a pseudo-inversion center midway between the molecular centers. Eight water molecules are also present in the unit cell.

KRYPTORACEMIC CRYSTALLIZATION. PART 4. SYNTHESIS AND X-RAY STRUCTURE OF THE CONGLOMERATE [Co(en)2Ox]F 11.5H2O(I), ANOTHER EXAMPLE OF A COORDINATION COMPOUND CRYSTALLIZING AS A KRYPTORACEMATE

Aracemic solution of [Co(en)2Ox]F 11.5H2O(I), CoFO15.5N4C6H39, crystallizes as a kryptoracemate in the enantiomorphic space group C2 (No. 5) with lattice constants: a = 21.150(19) Å, b= 11.866(8), c= 13.197(2) Å and β = 101.62(8)°; V= 3243.97 Å3 and d(calc; M.W. = 493.92 gm-mol−1, z = 8) = 2.020 g-cm3. A total of 2335 data were collected over the range of 4° ≤ 2θ ≤ 45°; of these, 1735 (independent and with I ≥ 2.5[sgrave](I)) were used in the structural analysis. Data were corrected for absorption (μ = 10.75 cm−1) and the relative transmission coefficients ranged from 0.5557 to 0.7852. Refinement converged to final residuals of 0.063 and 0.072 for R(F) and RW(F), respectively. There are two formula weights in the asymmetric unit of (I) and the absolute configuration was determined by the Flack test. For (I), the absolute configuration at Col is A(δλ.) and for Co2 is δ(λδ), which by comparision with the known absolute configurations of the chloride and bromide derivatives,4 allows us to assign the full chiro-optical symbol for these cations. Thus, the cations present in the crystal selected for the structural study of (I) are characterized fully by the symbols (+)589-A(λδ)-[Col(en)2Ox]F 1l. 5H2O and (-)589-δ(λδ)-[Co2(en)2Ox]F 11.5H2O. The two cations are located near a non-crystallographic, pseudo-inversion center located approximately at 1/4, 0, 1/4, as determined from the positions of the two independent Co atoms; however, this pseudo-inversion center is only approximately shared by the four nitrogens and two oxygens in the coordination sphere, and is seriously violated by the other atoms of the metal ligands. This is, to our knowledge, the first coordination compound of Co(III) which crystallizes, from a racemic solution, in an enantiomorphic lattice with a fluoride as its anion. Moreover, this is also the first fluoride to crystallize as a kryptoracemate.

Crystal structures of 1,1′-di(2-propanone)-2,2′-biimidazole dihydrazone and 2,6-diacetylpyridine dihydrazone

The nucleophilic addition reactions between 1,1′-di(2-propanone)-2,2′-biimidazole or 2,6-diacetylpyridine and hydrazine hydrate afford 1,1′-di(2-propanone)-2,2′-biimidazole dihydrazone (1) and 2,6-diacetylpyridine dihydrazone (2), respectively. Compound1 crystallizes in the orthorhombic space groupP212121, witha=9.042(2),b=9.731(3),c=15.683(4)A, V = 1379.9(6)Aℨ andZ=4. Compound2 crystallizes in the orthorhombic space groupPnma, witha=10.948(2),b=19.742(6),c=4.566(1)A, V=986.9(4)Aℨ andZ=8. A pseudo center of inversion is present at the midpoint of the C−C bond joining the imidazole rings of1, whose substituents crystallize in atrans configuration. The imidazole rings are rotated 2.5(3)° about the C−C bond. In contrast to the essentially planar structure of2, the hydrazone substituent groups of1 are at angles of 89.9(1)° and 88.4(1)° with respect to the plane of the adjacent imidazole moiety.

Substituted Imidazonaphthyridine Derivatives. III. C24H28N4, C24H28N4O and C23H25BrN4

The structures of three 1,2,6,8-tetrasubstituted imidazonaphthyridine derivatives, 1-diethylaminomethyl-6,8-dimethyl-2-(4-methylphenyl)imidazo[1,2-a] [1,8]naphthyridine, (VII), 1-diethylaminomethyl-2-(4-methoxyphenyl)-6,8-dimethylimidazo[1,2-a] [1,8]naphthyridine, (VIII), and 2-(4-bromophenyl)-1-diethylaminomethyl-6,8-dimethylimidazo[1,2-a] [1,8]naphthyridine, (IX), are reported. Two molecules related by a pseudo inversion centre are present in the asymmetric unit of (IX). Intramolecular C-H⋯N hydrogen bonds are observed in (VII) and (IX) whereas an intermolecular C-H⋯O hydrogen bond is present in (VIII).

(R,S)-1-Phenylethylammonium (R,S)-Mandelate

The asymmetric unit of the title compound, C 8 H 12 N + .C 8 H 7 O 3 - contains two 1-phenylethylammonium cations with opposite configurations and two (S)-mandelate anions (α-hydroxybenzeneacetate). The ions are shown to be nearly related by a pseudo inversion centre. This gives rise to an unusual conformation of one of the (S)-mandelate ions. An extensive hydrogen-bond system connects the ions in a similar way to the hydrogen-bond patterns found in (S)-1-phenylethylammonium (S)-mandelate and (R)-mandelate

2,6-Bis(phenylamino)pyridine

The structure of the title compound, C 17 H 15 N 3 , consists of two independant molecules which are connected by nearly linear weak N(amino)-H...N(pyridine) hydrogen bonds through a pseudo center of inversion to form a dimer. Conformationally, this symmetrically substituted pyridine derivative displays an E,E form. In this form the H-atom interactions between neighboring rings are reduced

Synthesis and characterization of N-methyliminodiacetato trans-R,R-, trans-S,S-, and cis-1,2-diaminocyclohexane platinum (IV) complexes: Crystal structure of chloro( trans-R,R-1,2-diaminocyclohexane) (N-methyliminodiacetato)platinum(IV) chloride

The compounds, chloro( trans-R,R-1,2-diaminocyclohexane)(N-methyliminodiacetato)platinum(IV) chloride, chloro( trans-S,S-1,2-diaminocyclohexane)(N-methyliminodiacetato)platinum(IV) chloride, and chloro( cis-1,2-diaminocyclohexane)(N-methyliminodiacetato)platinum(IV) chloride, were prepared and characterized by elemental analysis, IR, and 195Pt NMR. The crystal structure of one of these three compounds, chloro( trans-R,R-1,2-diammocyclohexane)(N-methyliminodiacetato)platinum(IV) chloride, was determined by x-ray single crystal diffraction. This compound is particularly interesting because the 1,2-diaminocyclohexane (DACH) ring is in a twist-boat configuration rather than the chair configuration previously reported for other DACH platinum compounds. The crystal structure consists of two independent cations and anions, with all atoms between these two independent molecules (except those in the chiral DACH) related by a pseudo-inversion center. Both platinum atoms have slightly distorted octahedral coordination, with angles ranging from 81.8 to 100.8°. Crystallographic details: space group P2 1 (monoclinic); a = 19.864(5) Å, b = 7.026(2) Å, c = 12.446(3) Å, β = 106.62(2)°; Z = 4; R = 0.036 for 2333 reflections.