2,4-Bis(2-fluoro­phen­yl)-3-aza­bicyclo­[3.3.1]nonan-9-one

The title compound, C20H19F2NO, exists in a twin-chair conformation with an equatorial orientation of the two 2-fluoro­phenyl groups on both sides of the secondary amine group. The benzene rings are orientated at an angle of 25.68 (4)° with respect to one another and the F atoms point upwards (towards the carbonyl group). The crystal is stabilized by an inter­molecular N—H⋯π inter­action

2,6-Bis(4-meth­oxy­phen­yl)-1,3-dimethyl­piperidin-4-one O-benzyl­oxime

The central ring of the title compound, C28H32N2O3, exists in a chair conformation with an equatorial disposition of all the alkyl and aryl groups on the heterocycle. The para-anisyl groups on both sides of the secondary amino group are oriented at an angle of 54.75 (4)° with respect to each other. The oxime derivative exists as an E isomer with the methyl substitution on one of the active methyl­ene centers of the mol­ecule. The crystal packing features weak C—H⋯O inter­actions

2,4-Bis(3-methoxy­phen­yl)-3-aza­bicyclo­[3.3.1]nonan-9-one

In the crystal structure, the title compound, C22H25NO3, exists in a twin-chair conformation with equatorial orientations of the meta-methoxy­phenyl groups on both sides of the secondary amino group. The title compound is a positional isomer of 2,4-bis­(2-methoxy­phen­yl)-3-aza­bicyclo­[3.3.1]nonan-9-one and 2,4-bis­(4-methoxy­phen­yl)-3-aza­bicyclo­[3.3.1]nonan-9-one, which both also exhibit twin-chair conformations with equatorial dispositions of the anisyl rings on both sides of the secondary amino group. In the title compound, the meta-methoxy­phenyl rings are orientated at an angle of 25.02 (3)° with respect to each other, whereas in the ortho and para isomers, the anisyl rings are orientated at dihedral angles of 33.86 (3) and 37.43 (4)°, respectively. The crystal packing is dominated by van der Waals inter­actions and by an inter­molecular N—H⋯O hydrogen bond, whereas in the ortho isomer, an inter­molecular N—H⋯π inter­action (H⋯Cg = 2.75 Å) is found

Fully ab initio atomization energy of benzene via W2 theory

The total atomization energy at absolute zero, (TAE$_0$) of benzene, C$_6$H$_6$, was computed fully {\em ab initio} by means of W2h theory as 1306.6 kcal/mol, to be compared with the experimentally derived value 1305.7+/-0.7 kcal/mol. The computed result includes contributions from inner-shell correlation (7.1 kcal/mol), scalar relativistic effects (-1.0 kcal/mol), atomic spin-orbit splitting (-0.5 kcal/mol), and the anharmonic zero-point vibrational energy (62.1 kcal/mol). The largest-scale calculations involved are CCSD/cc-pV5Z and CCSD(T)/cc-pVQZ; basis set extrapolations account for 6.3 kcal/mol of the final result. Performance of more approximate methods has been analyzed. Our results suggest that, even for systems the size of benzene, chemically accurate molecular atomization energies can be obtained from fully first-principles calculations, without resorting to corrections or parameters derived from experiment.Comment: J. Chem. Phys., accepted. RevTeX, 12 page

2,4-Bis(4-bromo­phen­yl)-3-aza­bicyclo­[3.3.1]nonan-9-one

The title compound, C20H19Br2NO, shows a chair–chair conformation for the aza­bicycle with an equatorial disposition of the 4-bromo­phenyl groups [dihedral angle between the aromatic rings = 16.48 (3)°]. In the crystal, a short Br⋯Br contact [3.520 (4) Å] occurs and the structure is further stabilized by N—H⋯O hydrogen bonds and C—H⋯O inter­actions

2,4-Bis(4-chloro­phen­yl)-3-aza­bicyclo­[3.3.1]nonan-9-one

In the mol­ecular structure of the title compound, C20H19Cl2NO, the mol­ecule exists in a twin-chair conformation with equatorial dispositions of the 4-chloro­phenyl groups on both sides of the secondary amino group; the dihedral angle between the aromatic ring planes is 31.33 (3)°. The crystal structure is stabilized by N—H⋯O inter­actions, leading to chains of molecules

2,6-Bis(4-chloro­phen­yl)-1,3-dimethyl­piperidin-4-one O-benzyl­oxime

The piperidin-4-one ring in the title compound, C26H26Cl2N2O, exists in a chair conformation with equatorial orientations of the methyl and 4-chlorophenyl groups. The C atom bonded to the oxime group is statistically planar (bond-angle sum = 360.0°) although the C—C=N bond angles are very different [117.83 (15) and 127.59 (15)°]. The dihedral angle between the chloro­phenyl rings is 54.75 (4)°. In the crystal, mol­ecules inter­act via van der Waals forces