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Crystal structures and conformations of two Diels-Alder adduct derivatives: 1,8-bis-(thio-phen-2-yl)-14-oxa-tetra-cyclo-[6.5.1.0(2,7).0(9,13)]tetra-deca-2(7),3,5-trien-10-one and 1,8-diphenyl-14-oxa-tetra-cyclo[6.5.1.0(2,7).0(9,13)] tetra-deca-2,4,6-trien-10-one.

Gopinath S, Narayanan P, Sethusankar K, Nandakumar M, Mohanakrishnan AK - Acta Crystallogr E Crystallogr Commun (2015)

Bottom Line: In (II), the oxygen atom of the cyclo-penta-none ring is rotationally disordered over two sites with an occupancy ratio of 0.579 (4):0.421 (4).The mol-ecular structure of (I) is stabilized by an intra-molecular C-H⋯O hydrogen bond, which generates an S(7) ring motif.The structure of (I) was refined with a twin scale factor of 0.275 (2).

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, RKM Vivekananda College (Autonomous), Chennai 600 004, India.

ABSTRACT
The title compounds, C21H16O2S2 (I) and C25H20O2 (II), are products of a tandem 'pincer' Diels-Alder reaction consisting of [2 + 2] cyclo-additions between benzo[c]furan and cyclo-penta-none. Each comprises a fused tetra-cyclic ring system containing two five-membered rings (in envelope conformations with the O atom as the flap) and six-membered rings (in boat conformations). In addition, two thio-phene rings in (I) and two phenyl rings in (II) are attached to the tetra-cyclic ring system. The cyclo-penta-none ring adopts a twisted conformation in (I) and an envelope conformation in (II). In (I), the thio-phene rings are positionally disordered over two sets of sites, with occupancy ratios of 0.901 (2):0.099 (2) and 0.666 (2):0.334 (2). In (II), the oxygen atom of the cyclo-penta-none ring is rotationally disordered over two sites with an occupancy ratio of 0.579 (4):0.421 (4). The mol-ecular structure of (I) is stabilized by an intra-molecular C-H⋯O hydrogen bond, which generates an S(7) ring motif. In the crystal, the mol-ecules are linked via weak C-H⋯O hydrogen bonds, which generate R (2) 2(16) ring motifs in (I) and C(8) chains in (II). In both structures, the crystal packing also features C-H⋯π inter-actions. The crystal studied of compound (I) was twinned by non-merohedry. The twin component is related by the twin law [-1 0 0 -0.101 1 -0.484 0 0 -1] operated by a twofold rotation axis parallel to the b axis. The structure of (I) was refined with a twin scale factor of 0.275 (2).

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The crystal packing of compound (II), viewed down the b axis, showing the C5—H5⋯O2i hydrogen bonds (dashed lines), which result in the formation of C(8) chains. Hydrogen atoms not involved in this hydrogen bond are excluded for clarity. [Symmetry code: (i) x − , −y + , z − .]
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fig4: The crystal packing of compound (II), viewed down the b axis, showing the C5—H5⋯O2i hydrogen bonds (dashed lines), which result in the formation of C(8) chains. Hydrogen atoms not involved in this hydrogen bond are excluded for clarity. [Symmetry code: (i) x − , −y + , z − .]

Mentions: In both structures, the crystal packing features C—H⋯O and C—H⋯π inter­actions (Tables 1 ▸ and 2 ▸). In compound (I), the C20—H20⋯O2(−x + 1, −y, −z + 1) hydrogen bond generates an (16) graph-set ring motifs around an inversion centre (Bernstein et al., 1995 ▸) while in compound (II), the weak C5—H5⋯O2(x − , −y + , z − ) hydrogen bond generates C(8) chains running parallel to the c axis. The resulting packing in (I) and (II) is shown in Figs. 3 ▸ and 4 ▸, respectively. The structures of both compounds also feature C—H⋯π inter­actions (Tables 1 ▸ and 2 ▸).


Crystal structures and conformations of two Diels-Alder adduct derivatives: 1,8-bis-(thio-phen-2-yl)-14-oxa-tetra-cyclo-[6.5.1.0(2,7).0(9,13)]tetra-deca-2(7),3,5-trien-10-one and 1,8-diphenyl-14-oxa-tetra-cyclo[6.5.1.0(2,7).0(9,13)] tetra-deca-2,4,6-trien-10-one.

Gopinath S, Narayanan P, Sethusankar K, Nandakumar M, Mohanakrishnan AK - Acta Crystallogr E Crystallogr Commun (2015)

The crystal packing of compound (II), viewed down the b axis, showing the C5—H5⋯O2i hydrogen bonds (dashed lines), which result in the formation of C(8) chains. Hydrogen atoms not involved in this hydrogen bond are excluded for clarity. [Symmetry code: (i) x − , −y + , z − .]
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4384542&req=5

fig4: The crystal packing of compound (II), viewed down the b axis, showing the C5—H5⋯O2i hydrogen bonds (dashed lines), which result in the formation of C(8) chains. Hydrogen atoms not involved in this hydrogen bond are excluded for clarity. [Symmetry code: (i) x − , −y + , z − .]
Mentions: In both structures, the crystal packing features C—H⋯O and C—H⋯π inter­actions (Tables 1 ▸ and 2 ▸). In compound (I), the C20—H20⋯O2(−x + 1, −y, −z + 1) hydrogen bond generates an (16) graph-set ring motifs around an inversion centre (Bernstein et al., 1995 ▸) while in compound (II), the weak C5—H5⋯O2(x − , −y + , z − ) hydrogen bond generates C(8) chains running parallel to the c axis. The resulting packing in (I) and (II) is shown in Figs. 3 ▸ and 4 ▸, respectively. The structures of both compounds also feature C—H⋯π inter­actions (Tables 1 ▸ and 2 ▸).

Bottom Line: In (II), the oxygen atom of the cyclo-penta-none ring is rotationally disordered over two sites with an occupancy ratio of 0.579 (4):0.421 (4).The mol-ecular structure of (I) is stabilized by an intra-molecular C-H⋯O hydrogen bond, which generates an S(7) ring motif.The structure of (I) was refined with a twin scale factor of 0.275 (2).

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, RKM Vivekananda College (Autonomous), Chennai 600 004, India.

ABSTRACT
The title compounds, C21H16O2S2 (I) and C25H20O2 (II), are products of a tandem 'pincer' Diels-Alder reaction consisting of [2 + 2] cyclo-additions between benzo[c]furan and cyclo-penta-none. Each comprises a fused tetra-cyclic ring system containing two five-membered rings (in envelope conformations with the O atom as the flap) and six-membered rings (in boat conformations). In addition, two thio-phene rings in (I) and two phenyl rings in (II) are attached to the tetra-cyclic ring system. The cyclo-penta-none ring adopts a twisted conformation in (I) and an envelope conformation in (II). In (I), the thio-phene rings are positionally disordered over two sets of sites, with occupancy ratios of 0.901 (2):0.099 (2) and 0.666 (2):0.334 (2). In (II), the oxygen atom of the cyclo-penta-none ring is rotationally disordered over two sites with an occupancy ratio of 0.579 (4):0.421 (4). The mol-ecular structure of (I) is stabilized by an intra-molecular C-H⋯O hydrogen bond, which generates an S(7) ring motif. In the crystal, the mol-ecules are linked via weak C-H⋯O hydrogen bonds, which generate R (2) 2(16) ring motifs in (I) and C(8) chains in (II). In both structures, the crystal packing also features C-H⋯π inter-actions. The crystal studied of compound (I) was twinned by non-merohedry. The twin component is related by the twin law [-1 0 0 -0.101 1 -0.484 0 0 -1] operated by a twofold rotation axis parallel to the b axis. The structure of (I) was refined with a twin scale factor of 0.275 (2).

No MeSH data available.


Related in: MedlinePlus