Redetermination of (η4-s-cis-1,3-butadiene)tricarbonyl­iron(0)

The crystal structure of the title compound, [Fe(C4H6)(CO)3], was previously reported by Mills & Robinson [Acta Cryst. (1963) ▶, 16, 758–761]. The compound crystallizes in the centrosymmetric space goup Pnma with the complex located on a mirror plane. The redetermination of this structure at 100 K yielded almost equilibrated C—C bond lengths within the butadiene ligand according to a metal-to-ligand bonding–back-bonding mechanism. The C—C bond lengths presented herein are significantly shorter than those reported earlier. The H-atom positions that have not been reported so far were located by difference Fourier maps. The positional parameters of all H atoms and individual U iso values were refined freely

Trimethyl­sulfonium 1-amino-6-fluoro-2,3,4,5,7,8,9,10,11,12-decaiodo-1-carba-closo-dodeca­borate

In the asymmetric unit of the title salt, C3H9S+·CH2B11FI10N− or (CH3)3S[1-H2N-6-F-closo-1-CB11I10], both ions lie in general positions. The anion is perfectly ordered and so the positions of the C—NH2 vertex and the fluorine substituent are clearly assigned. The relatively short C—N bond length may be inter­preted in terms of a very electron deficient {closo-1-CB11} cluster

Diisopropyl­ammonium methane­sulfonate

The title molecular salt, C6H16N+·CH3SO3 −, has been determined at 150 K. Two diisopropyl­ammonium cations (dipH) and two anions form N—H⋯O hydrogen-bonded cyclic dimers lying around centers of symmetry. Only two of the three O atoms of the methane­sulfonate anion are involved in hydrogen bonding, resulting in slightly longer S—O bond lengths. The title structure represents an example of a sulfonate anion that is part of a hydrogen-bonding R 4 4(12) graph-set motif, which is well known for related dipH acetates. Additionally, the Raman and the IR spectroscopic data for the title compound are presented

The pseudosymmetric structure of bis­(pentane-1,5-diaminium) iodide tris­(triiodide)

The asymmetric unit of the title compound, [H3N(CH2)5NH3]2I[I3]3 or 2C5H16N2 2+·3I3 −·I−, consists of two crystallographically independent pentane-1,5-diaminium dications and two triiodide anions in general positions besides two additional triiodide and two iodide anions located on twofold axes. The compound crystallizes in the centrosymmetric monoclinic space group P2/n. The structure refinement was handicapped by the pseudosymmetry (pseudo-centering) of the structure and by twinning. The crystal structure is composed of two alternate layers, which differ in their arrangement of the pentane-1,5-diaminium dications and the iodide/triiodide anions and which are connected via weak to medium–strong N—H⋯I hydrogen bonds, constructing a complex hydrogen-bonded network

Redetermination of diaqua­tetra­kis­(dimethyl­formamide-κO)magnesium dichloride

The crystal structure of the title compound, [Mg(C3H7NO)4(H2O)2]Cl2, in which the Mg ion lies on a crystallographic inversion centre, confirms that of the previous room-temperature study [Pavanello et al. (1995 ▶). Main Group Met. Chem. 18, 9–19]. This redetermination at 113 K has improved geometry precision by almost an order of magnitude [e.g. Mg—O(w) (w = water) distances = 2.094 (4) and 2.0899 (7) Å in the old and new structures, respectively] and allowed the water H atoms to be located and their positions refined. In the crystal, O—H⋯Cl hydrogen bonds between the two aqua ligands of the complex mol­ecule and neighboring chloride counter-anions generate supra­molecular chains propagating along [010]. The dicationic [Mg(DMF)4(H2O)2] unit (DMF is dimethyl­formamide) adopts a slightly distorted octa­hedral geometry in which the Mg atom is coordinated by four DMF O atoms in a pseudo-tetra­gonal arrangement and two trans aqua ligands

Ethane-1,2-diylbis(methyl­phosphinic acid)

In the title compound, C4H12O4P2, there are two crystallographically independent half-mol­ecules in the asymmetric unit, both molecules lying on centres of symmetry. Each mol­ecule is connected on both sides to neighbouring mol­ecules via strong O—H⋯O hydrogen bonds. The –POOH groups accept and donate one hydrogen bond in interactions with the neighbouring –POOH group of the adjacent mol­ecule, to give one-dimensional chains along [10]. As each phosphinic acid group donates and accepts one hydrogen bond, the connection between the mol­ecules is best described by a ring motif which can be classified by the Etter symbol R 2 2(8)

(Picolinato-κ2 N,O)[tris(2-isopropyl-1H-imidazol-4-yl-κN 3)phosphane]cobalt(II) nitrate

Single crystals of the title compound, [Co(C6H4NO2)(C18H27N6P)]NO3, were obtained from the reaction of nitrato[tris­(2-isopropyl­imidazol-4-yl)phosphane]cobalt(II) nitrate with picolinic acid in the presence of potassium tert-butoxide as base. The coordination polyhedron around the central CoII ion is about halfway between square-pyramidal and trigonal-bipyramidal geometry. In the structure, the nitrate counter-anion is connected by N—H⋯O hydrogen bonding to the complex cation. Additionally, the complex cations form one-dimensional chains along [010] by hydrogen bonding of the NH group of an imidazole ring to the picolinate group of a neighbouring complex cation

Tetra­ethyl­ammonium 12-phenyl­ethynylcarba-closo-dodeca­borate, [Et4N][12-PhCC-closo-CB11H11]

The asymmetric unit of the title compound, C8H20N+·C9H16B11 − or [Et4N][12-PhCC-closo-CB11H11], consists of one cation and one anion. The [12-PhCC-closo-CB11H11]− anion is close to possessing a non-crystallographic plane of mirror symmetry with a nearly linear B—C C—C group, with B—C C and C C—C angles of 177.15 (16) and 176.64 (17)°, respectively

Redetermination of trans-cyclo­hexane-1,4-diammonium dichloride

A redetermination of the crystal structure of the title compound, C6H16N2 2+·2Cl−, was undertaken. All atomic coordinates including those of the H atoms were refined freely. The cation is located on a centre of symmetry. Important for the crystal structure are wavy hydrogen-bonded layers that are formed by ammonium groups and chloride anions, giving hydrogen-bonded rings