Axial Chlorine Atoms Research Articles

Synthesis and structure of BIS(Trifluoromethyl)BIS(Tri-methylsilyl)Amino dichloroarsorane, (CF 3) 2AsCl 2N(SiMe 3) 2

The synthesis of (CF 3) 2AsCl 2N(SiMe 3) 2 is reported. This compound has been characterized on the basis of an X-ray analysis. It has a trigonal bipyramidal geometry with axial chlorine atoms. Variable temperature 1H- and 19F-NMR data show no observable changes. In comparison to pentacoordinated phosphorus compounds the tendency to form tetracoordinated derivatives is strongly diminished in the case of arsenic compounds.

ChemInform Abstract: NUCLEAR QUADRUPOLE RESONANCE AND STEREOCHEMISTRY. PART 7. THE AXIAL AND EQUATORIAL CHLORINE ATOMS IN OCTAHEDRAL COMPLEXES OF ANTIMONY PENTACHLORIDE, SBCL5L (L = DONOR LIGAND)

Chlorine-35 and 121,123Sb n.q.r. frequencies and their temperature dependencies for various octahedral complexes of antimony pentachloride, SbCl5L (L = donor ligand), are reported. Assignments of 35Cl resonances to axial or equatorial chlorine atoms of the SbCl5 fragment have been possible in some cases. There are no apparent systematic differences between the frequencies of the axial or equatorial chlorine atoms, such differences as there are being masked by crystal-field effects of similar magnitude.

Nuclear quadrupole resonance and stereochemistry. Part 7. The axial and equatorial chlorine atoms in octahedral complexes of antimony pentachloride, SbCl5L (L = donor ligand)

Chlorine-35 and 121,123Sb n.q.r. frequencies and their temperature dependencies for various octahedral complexes of antimony pentachloride, SbCl5L (L = donor ligand), are reported. Assignments of 35Cl resonances to axial or equatorial chlorine atoms of the SbCl5 fragment have been possible in some cases. There are no apparent systematic differences between the frequencies of the axial or equatorial chlorine atoms, such differences as there are being masked by crystal-field effects of similar magnitude.

Characterization of some high-spin iron(II) complexes with urea derivatives. The crystal structure of dichlorotetrakis(thiourea)iron(II)

Urea (ur), thiourea (tu) and diisopropylthiourea (diptu) form high-spin complexes with iron(II), for which57Fe Mossbauer quadrupole splitting and spectroscopic data suggest an octahedral distorted geometry. The x-ray diffraction study on Fe(tu)4Cl2 confirms this geometry. The crystals are tetragonal, space groupP42/n witha=13.71,c=8.94 A andZ=4. The molecules are centrosymmetric with two axial chlorine atoms (Fe-Cl=2.46 A) and four equatorial sulfur atoms (Fe-S=2.61 and 2.57 A respectively). A similartrans-octahedral geometry is proposed for the new Fe(diptu)4Cl2 complex and an octahedral metal coordination in the new [Fe(ur)6]Br2, Fe(tu)3Br2 and Fe(ur)3Br2 complexes.

Contribution de la résonance quadripolaire de 35Cl (RQN) á l'étude structurale de quelques chloro-5 Oxo-2 dioxathiannes-1,3,2 et de quelques chloro-5 dioxannes-1,3

The nuclear quadrupole resonance (NQR) signals detected in a series of 5-chloro-2-oxo-1, 3,2-dioxathianes and of 5-chloro-1,3-dioxanes, show a clear difference in frequencies between the lines attributable to the equatorial and the axial chlorine atoms: the observed shift ( v eq- v ax) is approximately 0.6 MHz. These results indicate that NQR spectroscopy may be of great value in the solution of structural problems involving compounds of this type.

The crystal and molecular structure of a paramagnetic, five-co-ordinate cobalt(III) compound : {NN′-bis[α-(2-amino-5-chlorophenyl)benzylidene]-ethane-1,2-diaminato(2-)-NN′N″N‴}chlorocobalt(III)–chloroform–dichloromethane (1/0.5/0.5)

Crystals of the title compound are monoclinic, a= 6.92(2), b= 16.19(5), c= 26.69(8)Å, β= 95.3(1)°, space group P21/c. A three dimensional X-ray analysis of the structure was made with counter data (1 303 independent reflections). The structure was solved by conventional Patterson and Fourier methods and refined by block-diagonal least squares to R 0.088. The [Co(N4)Cl] co-ordination polyhedron is square pyramidal (Co–N 1.84–1.92 Å); the cobalt atom lies 0.19 Å out of the N4 plane in the direction of the axial chlorine atom; there is an unusually long Co–Cl bond [2.507(2)Å]. The quadridentate ligand has a stepped conformation with the phenylene moieties approximately parallel and inclined at 173.9 and 172.6° to the N4 plane; the central chelate ring has a symmetrical gauche conformation.

Crystal structure of bis[hydroxo(triphenyl)arsonium(V)] dodeca-µ-chloro-hexachloro-octahedro-hexaniobate(2–)

The crystal structure of the title compound has been determined by single-crystal photographic X-ray diffraction methods. The structure was solved from photographic data by the heavy-atom method and refined by block-diagonal least-squares to R 0·13 for 2326 reflections. Crystals are monoclinic, space group, P21/n a= 15·76(2)b= 22·25(3), c= 8·62(1)A, β= 91·6(3)°Z= 2. The asymmetric unit is a [Ph3AsOH]+ cation and one half of a centrosymmetric [(Nb6Cl12)Cl6]2– anionic cluster unit. Bond lengths within the cation agree well with previously determined values for similar species (mean C–C 1·39, mean C–As 1·91 A); As–O is 1·73(2)A. The proximity of this bond to the special position (½,0,0), (0 ½,½) and the O–O′ distance of 2·80 A suggests that the cation oxygens are linked by a pair of hydrogen bonds. The point-symmetry of the cluster does not differ significantly from Oh the octahedron of niobium atoms (mean Nb–Nb 3·016A) being surrounded by the usual two sets of axial (6) and edge (12) chlorine atoms, (mean Nb–Cl 2·48 and 2·24 A). These distances differ significantly from those found in clusters of different oxidation state.

A correlation between p–cl bond lengths and35Cl nuclear quadrupole resonance frequencies in some cyclophosphazenes; the use of35Cl nuclear quadrupole resonance spectroscopy for structural assignments in cyclodiphosphazanes

The 35Cl n.q.r. spectra of a series of chlorocyclophosphazenes have been obtained and are discussed in the light of their known crystal structures. An approximately linear relationship exists between 35Cl n.q.r. frequencies and P–Cl bond lengths in closely related structures. The 35Cl n.q.r. spectra of the cyclodiphosphazanes, (Cl3PNR)2(R = Me, Et, or Ph), are reported. The axial and equatorial chlorine atoms in the trigonal bipyramidal distribution of atoms about phosphorus in the latter class of compound can be identified by their frequency ranges, and by relative changes in frequency with temperature.