Mary Mercer

A µ-dinitrogen complex with a long N–N bond. X-Ray crystal structure of [(PMe2Ph)4CIReN2MoCl4(OMe)]

The complex [(PMe2Ph)4CIReN2MoCI4(OMe)] has been prepared; it has µ(N2) at 1660 cm–1 and the N–N (1·21 A), Re–N (1·79 A), and Mo-N (1·89 A) bond distances, determined by X-ray crystallography are consistent with a linear Re–N–N–Mo delocalised bonding scheme.

The crystal structure of a ‘model carrier’ complex formed between sodium bromide and 2,3,11,12-dicyclohexyl-1,4,7,10,13,16-hexaoxocyclo-octadeca-2,11-diene (‘dicyclohexyl-18-crown-6’)

Abstract The determination of the crystal structure of a complex formed between sodium bromide and dicyclohexyl-18-crown-6 (IsomerB), has shown that the six oxygen atoms of the ligand form a planar ring round the sodium ion. The coordination sphere of the sodium ion is completed by two water molecules, one above and one below the plane of this ring. In the crystalline state the molecules are bonded into a chain system by H-bonds, which form between the water molecules and the bromide ions.

Crystal structure of a dinuclear dinitrogen complex: tetrachloro-{chlorotetrakis[dimethyl(phenyl)phosphine]rhenium(I)}-µ-dinitrogen-methoxymolybdenum(V)–methanol–hydrochloric acid

The crystal structure of the title complex has been determined from three-dimensional X-ray data. The N–N bond length is 1·18, with MO–N 1·90, and Re–N 1·82 A. These distances are consistent with a linear Re–N–N–Mo delocalised bonding scheme.The rhenium atom is octahedrally co-ordinated to four phosphorus atoms (Re–P 2·48 A), and a chlorine atom, trans to nitrogen (Re–Cl 2·42 A). The molybdenum atom is octahedrally co-ordinated to four chlorine atoms (mean Mo–Cl 2·39 A) and a methoxy-group trans to N (MO–O 2·15 A). The planes of phosphorus and chlorine atoms are parallel, and the atoms are in eclipsed positions.Crystals are monoclinic, space group P21/c, with a= 14·918(1), b= 11·176(2), c= 28·162(3)A, β= 9·6(1)°, Z= 4. The structure was solved by the heavy-atom method by use of 3589 independent reflections, measured on a diffractometer, and refined by block-diagonal least-squares to R 0·059.

Crystal structures of complexes between alkali-metal salts and cyclic polyethers. Part VII. Complex formed between dibenzo-24-crown-8 (6,7,9,10,12,13,20,21,23,24,26,27-dodecahydrodibenzo[b,n]-1,4,7,10,13,16,19,22-octaoxacyclotetracosin) and two molecules of potassium isothiocyanate

Potassium thiocyanate reacts with dibenzo-24-crown-8 giving crystals of formula C24H32O8,2KNCS. The molecular structure has been determined by three-dimensional X-ray analysis from diffractometer data. Crystals are monoclinic, space group P21/c, with Z= 2 in a unit cell of dimensions: a= 9·902(8), b= 18·55(4), c= 8·572(8)A, β= 106·9(2)°. All atoms, including hydrogen, were located. Full-matrix least-squares refinement led to a final R factor of 0·079 for 1184 independent reflections.The ligand oxygen atoms are almost coplanar, with potassium atoms 0·66 A on each side of this plane. Each K+atom is within bonding distance of five oxygen atoms, three bonding independently (K–O 2·732–2·825 A) and the fourth and fifth unequally shared between the two potassium atoms (K–O 2·898, 2·979 A). One thiocyanate ion is above and one below the ligand ring plane, each bridging the two potassium ions through nitrogen (K–N 2·87, 2·88 A). A benzene ring from another ligand is in a position for its π-electrons to form an electrostatic attraction to the potassium ion, so there are eight sources of electron density round the cation and the structure has three-dimensional electrostatic bonding throughout.

Preparation and crystal structure of a binuclear complex of potassium with one molecule of cyclic polyether: bis(potassium thiocyanate)dibenzo-24-crown-8

Reaction between potassium thiocyanate and 2,3,14,15-dibenzo-1,4,7,10,13,16,19,22-octaoxocyclotetracosa-2,14-diene gives a 2:1 complex shown by crystal structure analysis to be centrosymmetrical with two potassium ions each positioned among eight sources of electron density, namely, two nitrogen atoms of bridging thiocyanate groups, five oxygen atoms of the cyclic ether (two of the eight oxygen atoms are shared) and two carbon atoms of a benzene ring.

Crystal structures of complexes between alkali-metal salts and cyclic polyethers. Part VI. Complex formed between dicyclohexyl-18-crown-6, isomer B, (perhydrodibenzo[b,k][1,4,7,10,13,16]hexaoxacyclo-octadecin) and sodium bromide

A three-dimensional X-ray crystal structure analysjs has been carried out on the title complex, [Na(C20H36O6)(H2O)2]Br. Crystals are triclinic. Space group P, with a= 10·32(1), b= 11·34(1), c= 6·67(1)A, α= 116° 42′(6′), β= 109° 48′(5′), γ= 100° 10′(6′). The sodium ion lies on a centre of symmetry, and is surrounded by an approximately planar ring of six oxygen atoms of one ligand. (Na–O 2·67–2·97 A). The hexagonal bipyramidal arrangement about the sodium is completed by two water molecules, at 2·34 A. The water molecules form hydrogen bonds to the bromide ion, resulting in an infinite chain structure.1366 Intensities measured on a diffractometer were refined by full-matrix least-squares to R 0·046. All hydrogen atoms were located, except that involved in the hydrogen bond.