Dean H. Johnston

Ground state and photophysical properties of Ru(phen)2quo+: a strong excited state electron donor

Abstract We prepared the complex Ru(phen) 2 quo + (phen=1,10-phenanthroline, quo − =8-quinolate) and investigated its photophysical and redox properties. The absorption and emission of Ru(phen) 2 quo + are red-shifted relative to Ru(phen) 3 2+ , and the former is easier to oxidize than the latter. Ru(phen) 2 quo + possesses an Ru→phen MLCT (metal-to-ligand charge transfer) excited state ( E 00 ∼1.85 eV) that is a better reducing agent than the parent complex Ru(phen) 3 2+ . Transient absorption results are consistent with the formation of reduced methylviologen upon Ru(phen) 2 quo + excitation with visible light in water.

cis-Diamminedichloridoplatinum(II) N,N-dimethyl­formamide monosolvate

In the title compound, cis-[PtCl2(NH3)2]·C3H7NO, the metal complex molecules are stacked parallel to the b axis, forming close Pt⋯Pt interactions of 3.4071 (7) and 3.5534 (8) Å and 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-dimethylformamide molecules. 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).

4-Nitro-N-(3-nitro­phen­yl)benzamide

The title compound, C13H9N3O5, prepared as a solid derivative of 3-nitroanaline via reaction with 4-nitrobenzoyl chloride, crystallizes in a chiral space group. The molecule 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 molecules are stacked along the a axis with benzene ring centroid–centroid distances of 3.8878 (6) Å. In the crystal, intermolecular benzene C—H⋯O interactions involving one nitro group and the carbonyl group link the molecules, forming chains along [001]. An additional set of aromatic C—H⋯O interactions with the second nitro group form chains along [101], connecting adjacent chains to create layers perpendicular to the b axis.

Tris(3-nitropentane-2,4-dionato-κ2O,O′)cobalt(III)

The structure of the title compound, [Co(C5H6NO4)3], consists of a CoIII ion octahedrally coordinated by three bidentate 3-nitropentane-2,4-dionate ligands. The complex was prepared via the nitration of tris(2,4-pentanedionato-κ2 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-nitropentane-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 interactions with two different nitro groups to form chains running along the c axis. Additional C—H⋯O interactions are found between ligand methyl groups and the cobalt-bound O atoms, also resulting in the formation of chains along the c axis.

Tris(3-nitro­pentane-2,4-dionato-κ2O,O′)­cobalt(III)

The structure of the title compound, [Co(C5H6NO4)3], consists of a CoIII ion octahedrally coordinated by three bidentate 3-nitropentane-2,4-dionate ligands. The complex was prepared via the nitration of tris(2,4-pentanedionato-κ2 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-nitropentane-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 interactions with two different nitro groups to form chains running along the c axis. Additional C—H⋯O interactions are found between ligand methyl groups and the cobalt-bound O atoms, also resulting in the formation of chains along the c axis.

2,5-Dimethyl-1,3-dinitro­benzene

The title compound, C8H8N2O4, was prepared via the nitration of p-xylene. The molecules 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 interactions between the ring C—H and nitro groups of adjacent molecules 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-μ3-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.