Mwaffak Rukiah

Synthesis and crystal and molecular structures of N,N′-methylenedipyridinium tetrachlorozincate(II) and N,N′-methylenedipyridinium tetrachlorocadmate(II)

Treatment of N,N′-methylenedipyridinium dichloride [C5H5N-CH2-NC5H5]Cl2 with MCl2 (M = Zn or Cd) in aqueous solution gives the organic-inorganic hybrid ionic compounds [C5H5N-CH2-NC5H5] · [MCl4]. Both complex salts were fully characterised by multinuclear NMR spectroscopy, elemental analysis, and their molecular structures confirmed by powder X-ray diffraction studies. The most striking feature in both solid state structures was the presence of the C…Cl-M short contacts between the organic [C5H5N-CH2-NC5H5] dication and inorganic [MCl4] anion, which led to different crystal packing. For [C5H5N-CH2-NC5H5]·[ZnCl4], the C…Cl-Zn interactions led to the alternating arrangement of [C5H5N-CH2-NC5H5]2+[ZnCl4]2− to form 1-D chains in the direction [010], and each individual chain had a two-fold rotational axis along the b axis, while for [C5H5N-CH2-NC5H5] · [CdCl4] the C…Cl-Cd associations gave 2-D network. In both solid state structures, the presence of Cl-ring centroid distances gave a strong indication of some form of Cl-π interactions.

2-(Benzoylsulfanyl)acetic acid and 2,5-dioxopyrrolidin-1-yl 2-(benzoylsulfanyl)acetate by powder X-ray diffraction studies.

The structures of the title compounds, C(9)H(8)O(3)S, (I), and C(13)H(11)NO(5)S, (II), were determined by X-ray powder diffraction. Both were solved using the direct-space parallel tempering algorithm and refined using the Rietveld method. In (I), the C-S-C bond angle is slightly smaller than normal, indicating more p character in the bonding orbitals of the S atom. The carboxylic acid group joins across an inversion centre to form a dimer. The crystal packing includes a weak C-H···O hydrogen bond between an aromatic C-H group and a carboxylic acid O atom to form a two-dimensional network parallel to (10 ̅1). The C-S-C bond angle in (II) is larger than its counterpart in (I), indicating that the S atom of (II) has less p character in its bonding orbitals than that of (I), according to Bents rule. The crystal structure of (II) includes weak C-H···O hydrogen bonds between the H atoms of the methylene groups and carbonyl O atoms, forming a three-dimensional network.

\ 2,2,2-Trifluoro- N -(1a,2,7,7a-tetrahydronaphtho[2,3- b ]oxiren-3-yl)\ acetamide by X-ray powder diffraction

The title compound, C(12)H(10)F(3)NO(2), an important precursor in the preparation of benzovesamicol analogues for the diagnosis of Alzheimers disease, was prepared by the epoxidation of 5,8-dihydronaphthalen-1-amine using 3-chloroperoxybenzoic acid. The structure was determined by X-ray powder diffraction, multinuclear NMR spectroscopy and FT-IR spectroscopy. A pair of molecules form intermolecular N-H...O hydrogen bonds, involving the amino and oxirene groups, to produce a dimer.

N,N′-methylenedipyridinium Pt(II) and Pt(IV) hybrid salts: synthesis, crystal and molecular structures of [(C5H5N)2CH2] · [PtCl4] and [(C5H5N)2CH2] · [PtCl6]

The highly insoluble organic-inorganic hybrid ionic compounds N,N′-methylenedipyridinium tetrachloroplatinate(II) [(C5H5N)2CH2] · [PtCl4] and N,N′-methylenedipyridinium hexachloroplatinate(IV) [(C5H5N)2CH2] · [PtCl6] were obtained by the treatment of N,N′-methylenedipyridinium dichloride monohydrate [(C5H5N)2CH2]Cl2 · H2O with K2[PtCl4] or (NH4)2[PtCl6], respectively, in an aqueous solution. Both complexes were isolated, purified, characterised by elemental analysis, and their molecular structures were confirmed by powder X-ray diffraction. The crystal structure of both compounds consists of separated discrete dications [(C5H5N)2CH2]2+ and anions [PtCln]2− (n = 4 or 6). As anticipated, the dications formed a butterfly shape consisting of two pyridine rings bound to the methylene group via their N atoms, while the Pt centre had a square planar geometry in [(C5H5N)2CH2] · [PtCl4] and an octahedral coordination in [(C5H5N)2CH2] · [PtCl6]. Interestingly, both crystal structures are stabilised by intermolecular C-H…Cl non-standard hydrogen bonds, π-π ring interactions between two pyridine rings of adjacent dications, and also by Cl-π interactions.

Crystal structure of bis-[(1-ammonio-1-phosphono-eth-yl)phospho-nato]tetra-aqua-cadmium dihydrate: a powder X-ray diffraction study.

In the compound [CdL 2(H2O)4]·2H2O [L = (1-ammonio-1-phosphonoethyl)phosphonate, C2H8NO6P2 −], the CdII ion is situated on an inversion centre being coordinated by four aqua molecules in the equatorial plane and two deprotonated phosphonate O atoms from two L ligands in the axial positions in a distorted octahedral geometry. Each ligand L exists in a zwitterionic form, and with an intramolecular O—H⋯O interaction forming an S(6) ring motif and two intramolecular N—H⋯O interactions each generating an S(5) ring motif. In the crystal, N—H⋯O and O—H⋯O hydrogen bonds link complex molecules into a three-dimensional network with voids of 38 Å3 filled with ordered lattice water molecules, which are also involved in O—H⋯O hydrogen bonding.

Powder X-ray investigation of 4,4'-diisocyano-3,3'-dimethyl-biphen-yl.

The title compound, C16H12N2, was investigated in a powder diffraction study and its structure refined utilizing the Rietveld Method. The molecule has approximate C2 symmetry. The dihedral angle between the rings is 25.6 (7)°. The crystal packing is consolidated by weak C—H⋯C N hydrogen-bond-like contacts, which lead to the formation of a three-dimensional network. Further stabilization of the crystal structure is achived by weak non-covalent π–π interactions between aromatic rings, with a centroid–centroid distance of 3.839 (8) Å.

Poly[[μ-(1-azaniumylethane-1,1-diyl)bis(hydrogen phosphonato)]sodium]: a powder X-ray diffraction study.

The title two-dimensional coordination polymer, [Na(C₂H₈NO₆P₂)]n, was characterized using powder X-ray diffraction data and its structure refined using the Rietveld method. The asymmetric unit contains one Na⁺ cation and one (1-azaniumylethane-1,1-diyl)bis(hydrogen phosphonate) anion. The central Na⁺ cation exhibits distorted octahedral coordination geometry involving two deprotonated O atoms, two hydroxy O atoms and two double-bonded O atoms of the bisphosphonate anion. Pairs of sodium-centred octahedra share edges and the pairs are in turn connected to each other by the biphosphonate anion to form a two-dimensional network parallel to the (001) plane. The polymeric layers are connected by strong O-H∙∙∙O hydrogen bonding between the hydroxy group and one of the free O atoms of the bisphosphonate anion to generate a three-dimensional network. Further stabilization of the crystal structure is achived by N-H∙∙∙O and O-H∙∙∙O hydrogen bonding.

Poly[[μ-(1-ammonio-ethane-1,1-di-yl)bis-(hydrogenphospho-nato)]diaquachloridodisodium]: a powder X-ray diffraction study.

The title compound, [Na2(C2H8NO6P2)Cl(H2O)2]n, has a polymeric two-dimensional structure extending parallel to (001). The asymmetric unit contains two Na+ cations located on a centre of symmetry and on a mirror plane, respectively, one half of a bis-phosphonate anion (the entire anion is completed by mirror symmetry), one chloride anion on a mirror plane and one water molecule in general positions. The two Na+ cations exhibit distorted octahedral NaCl2O4 coordination polyhedra, each consisting of two deprotonated O atoms of the bis-phosphonate anion, of two water molecules and of two chloride anions. Strong O—H⋯O hydrogen bonds between the –OH group and one of the free O atoms of the bis-phosphonate anion connect adjacent layers along [100], supported by N—H⋯Cl interactions. Intralayer O—H⋯O and N—H⋯O hydrogen bonds are also observed.

Powder study of poly[(μ2-2,2-dimethylpropane-1,3-diyl diisocyanide)-μ2-iodido-silver(I)]

In order to explore the chemistry of the bidentate ligand 2,2-dimethylpropane-1,3-diyl diisocyanide and to investigate the effect of counter-ions on the polymeric structure of (2,2-dimethylpropane-1,3-diyl diisocyanide)silver(I) complexes, the title polymeric compound, [AgI(C(7)H(10)N(2))](n), was synthesized by treatment of 2,2-dimethylpropane-1,3-diyl diisocyanide with AgI. X-ray powder diffraction studies show, as expected, a polymeric structure, similar to the very recently reported Cl(-) and NO(3)(-) analogues [AgX(C(7)H(10)N(2))](n) (X = Cl(-) or NO(3)(-)). In the title structure, the Ag(I) centre is bridged to two adjacent Ag(I) neighbours by bidentate 2,2-dimethylpropane-1,3-diyl diisocyanide ligands via the NC groups to form [Ag{CNCH(2)C(CH(3))(2)CH(2)NC}](n) chains. The iodide counter-ions crosslink the Ag(I) centres of the chains to form a two-dimensional polymeric {[Ag{CNCH(2)C(CH(3))(2)CH(2)NC}]I}(n) network. This study also shows that this bidentate ligand forms similar polymeric structures on treatment with AgX, regardless of the nature of the counter-ion X(-), and also has a strong tendency to form polymeric complexes rather than dimeric or trimeric ones.

Crystal structures of crotonaldehyde semicarbazone and crotonaldehyde thiosemicarbazone from X-ray powder diffraction data

Crotonaldehyde semicarbazone and crotonaldehyde thiosemicarbazone show the same E conformation around the imine C=N bond. Each molecule has an intramolecular N—H⋯N hydrogen bond, which generates an S(5) ring. Intermolecular N—H⋯O hydrogen bonds in the semicarbazone link the molecules into layers parallel to the bc plane, while weak intermolecular N—H⋯S hydrogen bonds in the thiosemicarbazone link the molecules into chains propagating in [110].