Crystal structures and hydrogen-bonding analysis of a series of benzamide complexes of zinc(II) chloride.

Ionic co-crystals are co-crystals between organic mol-ecules and inorganic salt coformers. Co-crystals of pharmaceuticals are of inter-est to help control polymorph formation and potentially improve stability and other physical properties. We describe the preparation, crystal structures, and hydrogen bonding of five different 2:1 benzamide or tolu-amide/zinc(II) chloride co-crystal salts, namely, bis-(benzamide-κO)di-chlorido-zinc(II), [ZnCl2(C7H7NO)2], di-chlor-ido-bis-(2-methyl-benzamide-κO)zinc(II), [ZnCl2(C8H9NO)2], di-chlorido-bis-(3-methyl-benzamide-κO)zinc(II), [ZnCl2(C8H9NO)2], di-chlorido-bis-(4-methyl-benzamide-κO)zinc(II), [ZnCl2(C8H9NO)2], and di-chlorido-bis-(4-hy-droxy-benzamide-κO)zinc(II), [ZnCl2(C7H7NO2)2]. All of the complexes contain hydrogen bonds between the amide N-H group and the amide carbonyl oxygen atoms or the chlorine atoms, forming extended networks.

Teaching Cheminformatics through a Collaborative Intercollegiate Online Chemistry Course (OLCC).

While cheminformatics skills necessary for dealing with an ever-increasing amount of chemical information are considered important for students pursuing STEM careers in the age of big data, many schools do not offer a cheminformatics course or alternative training opportunities. This paper presents the Cheminformatics Online Chemistry Course (OLCC), which is organized and run by the Committee on Computers in Chemical Education (CCCE) of the American Chemical Society (ACS)'s Division of Chemical Education (CHED). The Cheminformatics OLCC is a highly collaborative teaching project involving instructors at multiple schools who teamed up with external chemical information experts recruited across sectors, including government and industry. From 2015 to 2019, three Cheminformatics OLCCs were offered. In each program, the instructors at participating schools would meet face-to-face with the students of a class, while external content experts engaged through online discussions across campuses with both the instructors and students. All the material created in the course has been made available at the open education repositories of LibreTexts and CCCE Web sites for other institutions to adapt to their future needs.

Bis(2,4-dioxo-pentan-3-ido-κ2 O,O')dioxidomolyb-denum(VI): a redetermination.

The title compound, [Mo(C5H7O2)2O2] or cis-[MoO2(acac)2] (acac is acetyl-acetonate), contains a molybdenum(VI) atom coordinated by two acetyl-acetonate ligands and two doubly bonded oxido ligands in a distorted octa-hedral shape. The mol-ecule is chiral and the asymmetric unit contains two independent mol-ecules (one Δ, one Λ). Extensive C-H⋯O contacts are present throughout the structure. Data were collected at 100 K, providing higher precision of unit-cell parameters and atomic positions than previous determinations [Kamenar et al. (1973 ▸). Cryst. Struct. Commun. 2, 41-44.; Krasochka et al. (1975). Zh. Strukt. Khim. 16, 696-698].

Crystal structures and hydrogen-bonding analysis of a series of solvated ammonium salts of molybdenum(II) chloride clusters.

Charge-assisted hydrogen bonding plays a significant role in the crystal structures of solvates of ionic com-pounds, especially when the cation or cations are primary ammonium salts. We report the crystal structures of four ammonium salts of molybdenum halide cluster solvates where we observe significant hydrogen bonding between the solvent molecules and cations. The crystal structures of bis-(anilinium) octa-µ3-chlorido-hexa-chlorido-octa-hedro-hexa-molybdate N,N-di--methyl-formamide tetra-solvate, (C6H8N)2[Mo6Cl8Cl6]·4C3H7NO, (I), p-phenyl-enedi-ammonium octa-µ3-chlorido-hexa-chlorido-octa-hedro-hexa-mol-yb-date N,N-di-methyl-formamide hexa-solvate, (C6H10N2)[Mo6Cl8Cl6]·6C3H7NO, (II), N,N'-(1,4-phenyl-ene)bis-(propan-2-iminium) octa-µ3-chlorido-hexa-chlo-rido-octa-hedro-hexa-molybdate acetone tris-olvate, (C12H18N2)[Mo6Cl8Cl6]·3C3H6O, (III), and 1,1'-dimethyl-4,4'-bipyridinium octa-µ3-chlo-rido-hexa-chlorido-octa-hedro-hexa-molybdate N,N-di-methyl-formamide tetra-solvate, (C12H14N2)[Mo6Cl8Cl6]·4C3H7NO, (IV), are reported and described. In (I), the anilinium cations and N,N-di-methyl-formamide (DMF) solvent mol-ecules form a cyclic R 4 2(8) hydrogen-bonded motif centered on a crystallographic inversion center with an additional DMF mol-ecule forming a D(2) inter-action. The p-phenyl-enedi-ammonium cation in (II) forms three D(2) inter-actions between the three N-H bonds and three independent N,N-di-methyl-formamide mol-ecules. The dication in (III) is a protonated Schiff base solvated by acetone mol-ecules. Compound (IV) contains a methyl viologen dication with N,N-di-methyl-formamide mol-ecules forming close contacts with both aromatic and methyl H atoms.

cis-Diamminedichloridoplatinum(II) N,N-dimethyl-formamide monosolvate.

In the title compound, cis-[PtCl2(NH3)2]·C3H7NO, the metal complex mol-ecules are stacked parallel to the b axis, forming close Pt⋯Pt inter-actions of 3.4071 (7) and 3.5534 (8) Šand weak N-H⋯Cl hydrogen bonds between the ammine ligand and the Cl atoms of the neighboring complex. Conventional N-H⋯O hydrogen bonds are formed between ammine ligands and the O atom of adjacent N,N-dimethyl-formamide mol-ecules. The crystal was found to be a split crystal and was analyzed using two domains related by a rotation of ca 4.4° about the reciprocal axis (-0.351 1.000 0.742) and refined to give a minor component fraction of 0.084 (6).

Tris(3-nitro-pentane-2,4-dionato-κO,O')-cobalt(III).

The structure of the title compound, [Co(C(5)H(6)NO(4))(3)], consists of a Co(III) ion octahedrally coordinated by three bidentate 3-nitro-pentane-2,4-dionate ligands. The complex was prepared via the nitration of tris-(2,4-penta-nedionato-κ(2)O,O')cobalt(III) with a solution of copper(II) nitrate in glacial acetic acid. The central C atom and the nitro group of one 3-nitro-pentane-2,4-dionate ligand are disordered over two positions with an occupancy ratio of 0.848 (4):0.152 (4). A second nitro group is also disordered over two orientations with an occupancy ratio of 0.892 (7):0.108 (7). Two of the ligand methyl groups form C-H⋯O inter-actions with two different nitro groups to form chains running along the c axis. Additional C-H⋯O inter-actions are found between ligand methyl groups and the cobalt-bound O atoms, also resulting in the formation of chains along the c axis.

4-Nitro-N-(3-nitro-phen-yl)benzamide.

The title compound, C(13)H(9)N(3)O(5), prepared as a solid derivative of 3-nitro-analine via reaction with 4-nitro-benzoyl chloride, crystallizes in a chiral space group. The mol-ecule is non-planar with a dihedral angle of 26.1 (1)° between the two benzene rings. Both nitro groups are twisted slightly out of the plane of their corresponding benzene rings, making dihedral angles of 10.7 (4) and 13.5 (4)°. The mol-ecules are stacked along the a axis with benzene ring centroid-centroid distances of 3.8878 (6) Å. In the crystal, inter-molecular benzene C-H⋯O inter-actions involving one nitro group and the carbonyl group link the mol-ecules, forming chains along [001]. An additional set of aromatic C-H⋯O inter-actions with the second nitro group form chains along [101], connecting adjacent chains to create layers perpendicular to the b axis.

2,5-Dimethyl-1,3-dinitro-benzene.

The title compound, C(8)H(8)N(2)O(4), was prepared via the nitration of p-xylene. The mol-ecules are stacked along the c axis in an antiparallel manner. The two nitro groups are rotated relative to the benzene ring with dihedral angles of 44.50 (7) and 31.67 (8)°. The tilt of the nitro groups allows the formation of C-H⋯O inter-actions between the ring C-H and nitro groups of adjacent mol-ecules creating puckered sheets perpendicular to the c axis. The H atoms of the methyl group in the 5-position are disordered (60° rotation) with an occupancy of 0.616 (19) for the major component. The crystal was found to be a non-merohedral twin with a twin law [-1 -0.002 0.005, 0.00031 -1 0.002, 0.118 -0.007 1] corresponding to a rotation of 180° about the reciprocal axis (001) and refined to give a minor component fraction of 0.320 (2).

A low-temperature phase of bis(tetrabutylammonium) octa-µ(3)-chlorido-hexachlorido-octahedro-hexatungstate.

The title compound, (C(16)H(36)N)(2)[W(6)Cl(14)], undergoes a reversible phase transition at 268 (1) K. The structure at 150 and 200 K has monoclinic (P2(1)/c) symmetry. Both crystallographically independent tungsten chloride cluster anions sit on crystallographic inversion centers [symmetry codes: (-x, -y + 1, -z) and (-x + 1, -y + 2, -z)]. Two previous studies at room temperature describe the structure in the space group P2(1)/n with a unit-cell volume approximately half the size of the low-temperature unit cell [Zietlow, Schaefer et al. (1986). Inorg. Chem. 25, 2195-2198; Venkataraman et al. (1999). Inorg. Chem. 38, 828-830]. The unit cells of the room- and low-temperature polymorphs are closely related. The hydrocarbon chain of one of the tetrabutylammonium cations is disordered at both 150 and 200 K.

Photoinduced one-electron reduction of alkyl halides by dirhodium(II,II) tetraformamidinates and a related complex with visible light.

Various substituted dirhodium tetraformamidinate complexes, Rh(2)(R-form)(4) (R = p-CF(3), p-Cl, p-OCH(3), m-OCH(3); form = N,N'-diphenylformamidinate), and the new complex Rh(2)(tpgu)(4) (tpgu = 1,2,3-triphenylguanidinate) have been investigated as potential agents for the photoremediation of saturated halogenated aliphatic compounds, RX (R = alkyl group). The synthesis and characterization of the complexes is reported, and the crystal structure of Rh(2)(tpgu)(4) is presented. The lowest energy transition of the complexes is observed at approximately 870 nm and the complexes react with alkyl chlorides and alkyl bromides under low energy irradiation (lambda(irr) > or = 795 nm), but not when kept in the dark. The metal-containing product of the photochemical reaction with RX (X = Cl, Br) is the corresponding mixed-valent Rh(2)(II,III)X (X = Cl, Br) complex, and the crystal structure of Rh(2)(p-OCH(3)-form)(4)Cl generated photochemically from the reaction of the corresponding Rh(2)(II,II) complex in CHCl(3) is presented. In addition, the product resulting from the dimerization of the alkyl fragment, R(2), is also formed during the reaction of each dirhodium complex with RX. A comparison of the dependence of the relative reaction rates on the reduction potentials of the alkyl halides and their C-X bond dissociation energies are consistent with an outer-sphere mechanism. In addition, the relative reaction rates of the metal complexes with CCl(4) decrease with the oxidation potential of the dirhodium compounds. The mechanism of the observed reactivity is discussed and compared to related systems.

Unidirectional current in a polyacetylene hetero-ionic junction.

Unidirectional electronic current is reported for a device based on the interface between an anionically functionalized and a cationically functionalized polyacetylene. The unidirectional current in this mixed ionically/electronically conducting system is electronic but is regulated by asymmetry in the ionic processes.

Ground-State Properties and Excited-State Reactivity of 8-Quinolate Complexes of Ruthenium(II).

In an effort to explore new systems with highly reducing excited states, we prepared a series of Ru(II) complexes of the type Ru(L)(2)quo(+) (L = bpy (2,2'-bipyridine), phen (1,10-phenanthroline), dmphen (4,7-dimethyl-1,10-phenanthroline), tmphen (3,4,7,8-tetramethyl-1,10-phenanthroline); quo(-) = 8-quinolate) and investigated their photophysical and redox properties. The absorption and emission spectra of the Ru(L)(2)quo(+) are significantly red-shifted relative to those of the parent complexes Ru(L)(3)(2+), with emission maxima in the 757-783 nm range in water. The Ru(L)(2)quo(+) systems are easily oxidized with E(1/2)(Ru(III/II)) values ranging from +0.62 to +0.70 V vs NHE, making the emissive Ru --> phen MLCT (metal-to-ligand charge transfer) excited states (E(00) approximately 1.95 eV in CH(3)CN) of the Ru(L)(2)quo(+) complexes significantly better reducing agents than the MLCT states of the parent Ru(L)(3)(2+) complexes. Emission lifetimes of 17.0 and 32.2 ns were measured for Ru(phen)(2)quo(+) in water and acetonitrile, respectively, and 11.4 ns for Ru(bpy)(2)quo(+) in water. Transient absorption results are consistent with the formation of reduced methyl viologen upon Ru(phen)(2)quo(+) excitation with visible light in water. The possibility of observing the Marcus inverted region in the forward bimolecular electron transfer reaction from the highly reducing Ru(phen)(2)quo(+) excited state was explored with neutral electron acceptors with reduction potentials ranging from +0.25 to -1.15 V vs NHE.