Dirk J. A. De Ridder

Synthesis and characterization of a stable bis-naphthyltin(II) compound.Bis[8-(dimethylamino)-1-naphthyl-C,N]tin(II) and its W(CO)5 adduct

Reaction of [8-(dimethylamino)-1-naphthyl-C, N]lithium with SnCl{2} affords the new monomeric stannylene bis[8-(dimethylamino)-1-naphthyl-C,N]tin(II) (3). The reaction between W(CO){5}(NME{3}) and 3 yields {bis[8-(dimethylamino)-1-naphthyl-C,N]tin(II)} tungsten pentacarbonyl (4). The crystal structures of 3 and 4 have been determined by X-ray diffraction methods. 3: C{2}{4}H{2}{4}N{2}Sn, orthorhombic, space group Pbca with a 22.383(4), b 30.865(5), c 12.127(2) @9 and Z = 16, final R = 0.067 for 4983 observed reflections. 4: C{2}{9}H{2}{4}N{2}O{5}SnW, a 12.509(3), b 15.191(1), c 9.780(1) @9, @a 98.42(1), @b 104.33(1), @c 107.27(1)}o{, space group P1, Z = 2, triclinic; R = 0.046 for 7116 observed reflections. The geometry about tin in 3 is distorted @j-trigonal bypyramidal, and that in 4 is distorted trigonal bipyramidal. In both 3 and 4 the 8-(dimethylamino)-1-naphthyl groups are C,N-chelate bonded, with the C(1) atoms at equatorial sites and the nitrogen atoms at axial sites. The Sn lone pair in 3 and the W(CO){5} moiety in 4 occupy the remaining equatorial sites. }1{H, }1{}3{C, and }1{}1{}9{Sn solution NMR spectroscopic studies of 3 and 4 show that at low temperature (=< - 15}o{C) they retain the structures found in the solid state. At higher temperatures fluxional processes become operative.

Crystal structure of the inclusion complex of β-cyclodextrin with mefenamic acid from high-resolution synchrotron powder-diffraction data in combination with molecular-mechanics calculations

The crystal structure of the inclusion complex of beta-cyclo-dextrin with mefenamic acid has been determined from a combination of high-resolution synchrotron powder-diffraction data and molecular-mechanics calculations. A grid search indicates two possible solutions, which are corroborated by molecular-mechanics calculations, while Rietveld-refinement results suggest the crystal structure that is more likely to be formed in the solid state. Mefenamic acid is partially included in beta-cyclodextrin with either the xylyl or the benzoic-acid moiety being inside its cavity. In both solutions mefenamic acid and beta-cyclodextrin form a monomeric complex in a herringbone packing scheme.

Di-μ-chloro-bis[(cis,cis-η4-1,5-cyclooctadiene)rhodium(I)]: a redetermination

The structure of [Rh 2 Cl 2 (C 8 H 12 ) 2 ] has been redetermined. The precision of this structure determination compared with other published data shows an improvement such that average bond distance and angle e.s.d.s are smaller by a factor of two. The bond distances in the cis,cis-1,5-cyclooctadiene ring are compared to those of analogous compounds in the Cambridge Structural Database. The title compound has no molecular symmetry; the cis,cis-1,5-cyclooctadiene rings each have a boat conformation showing C 2v symmetry

Tris(η5-cyclopentadienyl)phenolatoneptunium(IV)

The geometry of [(η5-C5H5)3NpIV(OC6H5)] is compared with that of the isostructural uranium analogue.

Bis(cyclooctatetraenyl)neptunium(IV)

The crystal structure of neptunocene, [Np(C 8 H 8 ) 2 ], has been determined by single-crystal X-ray diffraction and is isostructural with thorocene and uranocene. A number of crystallographic and geometric parameters of these three compounds are compared.

The influence of ortho substituents on the twisting angle of a nitro group with respect to aromatic six-membered carbon rings

Examples of aromatic six-membered carbon rings carrying a nitro group with (a) zero, (b) one and (c) two substituents in the ortho position have been retrieved from organic molecules in the Cambridge Structural Database. The 270 fragments of type (a), 392 fragments of type (b) and 82 fragments of the (c) have been used to examine the distributions of the rotation of the nitro group out of the aromatic plane, the nitro group bending out of the latter plane and the nitro group bending into this plane, resulting in different exocyclic angles. The analyses show that the out-of-plane rotation angle of a nitro group depends on the steric hindrance caused by one or two adjacent groups, the electronegativity of the adjacent group(s) and the crystal packing. The comparison of this angle for a number of nitrobenzene musk compounds with respect to the structure-activity theory of Beets indicates that this descriptor is not a determining factor for muskiness

Lead tartrate from X-ray powder diffraction data.

The structure of lead tartrate, Pb(2+).C(4)H(4)O(6)(2-), has been solved from X-ray powder diffraction data. The cation exhibits ninefold coordination and the tartrate groups are linked through Pb.O contacts to form a three-dimensional network.

X-ray powder diffraction data and crystal data of polymorphic form 2 of carnidazole

The indexed powder diffraction pattern and related crystallographic data for polymorphic form 2 of carnidazole (C 8 H 12 N 4 O 3 S) are reported, as a first step in the structure determination by powder diffraction methods. The unit cell dimensions were determined from high resolution synchrotron powder diffraction data ( λ =0.079 998 0 nm) and evaluated by indexing programs. The monoclinic cell found for this polymorph is a =1.3908(2) nm, b =08094(2) nm, c =1.0645(2) nm, β =110.82(2)°, V =1.12015(27)nm 3 , Z =4, D x =1.445 Mg∕m 3 .

Structure of 1,3,5-triisopropyl-2-nitrobenzene

The nitro group in 1,3,5-triisopropyl-2-nitrobenzene is almost perpendicular to the aromatic ring. The crystal structure is disordered, which is indicated by the large U eq values of the atoms of the four substituent groups. The C-C distances in the isopropyl groups lie with the range 1.30-1.55 A

Influence of aromatic sulfonation on the geometry of [2.2]paracyclophane: crystal structures of one sulfonate, one disulfonic anhydride and five disulfonimides,

The crystal structures of potassium [2.2]paracyclophane-4-sulfonate (1), [2.2]paracyclophane-4,15-disulfonic anhydride (2), [2.2]paracyclophane-4,15-disulfonimide (3), N-n-propyl-[2.2]paracyclophane-4,15-disulfonimide (4), N-isopropyl-[2.2]paracyclophane-4,15-disulfonimide (5), N-cyclopropyl-[2.2]paracyclophane-4,15-disulfonimide (6) and N-phenyl-[2.2]paracyclophane-4,15-disulfonimide (7) were established by single-crystal X-ray diffraction. The structural changes caused by sulfonation are discussed with respect to the parent [2.2]paracyclophane (tricyclo[8.2.2.2(4,7)]hexadeca-4,6,10,12,13,15-hexaene). The main features are a change in the non-bonding distances between the para-phenylene rings and a rotation of these rings with respect to the molecular symmetry plane. The rings are rotated away from each other in the case of monosulfonation (1), but are rotated in the opposite way in the case of the disulfonic anhydride (2) or the disulfonimide compounds (3)-(7). The results are also discussed in terms of the parameters proposed by Keehn [(1983), Organic Chemistry, A Series of Monographs 45, edited by P. H. Keehn & S. M. Rosenfeld, Vol. 1, pp. 69-238. New York: Academic Press] showing that (bonded and non-bonded) angles involving the para-phenylene rings are mainly affected.