Donald Taylor

Crystal structure of dicaesium octa-µ3-chloro-hexachloro-octahedro-hexa-tungstate(II) and -molybdate(II) complexes

The crystal structures of the title compounds have been determined from single-crystal photographic X-ray diffraction data by Patterson and Fourier techniques, and refined by block-diagonal least-squares methods. Cs2[(W6Cl8)Br6] : trigonal, P31c, a= 10·07 ± 0·03, c= 14·75 ± 0·01 A; Z= 2; R= 0·11 for 665 observed reflections. Cs2[(Mo6Cl8)Br6] : trigonal, P31c, a= 10·06 ± 0·02, c= 14·70 ± 0·01 A, Z= 2; R 0·12 for 598 observed reflections.The anion consists of an octahedral cluster of metal atoms with the chlorine atoms bridging the octahedral faces and the bromine atoms axially co-ordinated to the M6 core. The mean metal–metal distances are W–W 2·620 ± 0·007 and Mo–Mo 2·615 ± 0·006 A. Other bonding distances are as expected. Implications of the structure concerning the vibrational spectrum are discussed. Cell dimensions are given for the range of isomorphous complexes Cs2[(M6Cl8)Y6], M = Mo or W; Y = Cl, Br, or I.

Ring expansion in a metal–dithiocarbamate complex by oxygen insertion; synthesis and properties of [Cr(S2CNR2)2(OS2CNR2)]. The X-ray structure of bis[NN-diethyl(dithiocarbamato-SS′)][NN-diethyl(dithioperoxycarbamato-OS)]chromium(III)

The synthesis and properties of the new complexes [Cr(S2CNR2)2(OS2CNR2)](R = Me or Et), in which one dithiocarbamate ligand has been oxidized to the hitherto unknown dithioperoxycarbamate ligand, are described; expansion of the chelate ring is confirmed from a single crystal X-ray structural analysis of the diethyl derivative.

Synthesis and X-ray structure of bis(diethyldithiocarbamato)(µ-dichloro)-dicopper(II), Cu2(Et2dtc)2Cl2, and the X-ray structure of Cu3(Et2dtc)2Cl3, an unusual mixed valence CuII, CuI reduction product

The preparation and crystal structure of the dimeric chloro-bridged copper(II) dithiocarbamate complex, Cu2(Et2dtc)2Cl2, are described, together with the crystal structure of a related minor product, Cu3(Et2dtc)2-Cl3, which proves to be an unusual mixed valence CUII/CUI polymer.

Sterically hindered co-ordination sites in metal complexes. Part 2. Structural characterisation of two ligand conformations in the nickel(II) complex of the ‘fly-over’ ligand 2,2′-tetramethylenedioxydi(8-N-salicylideneiminonaphthalene)

The crystal and molecular structure of the title complex has been determined at 295 K from three-dimensional X-ray diffraction data measured by counter techniques. The complex crystallises in the monoclinic space group P21/c with a= 18.631(1), b= 35.524(2), c= 9.756(1)A, β= 111.21(1)°, U= 6 019.6 A3, and Z= 8. The structure has been solved by conventional Patterson and Fourier techniques and refined by block-diagonal least squares to final residuals of R= 0.043, R′= 0.058 for 7 179 independent reflections with I/σ(I) 3.0. The trans-planar ‘capped’ structure proposed in Part 1 is confirmed (Ni–O, mean 1.820 A; Ni–N, mean 1.910 A) although it emerges that the dimensions and shape of the cavity are markedly sensitive to which of two conformations is adopted by the polymethylene bridging group. The details of the structures of the two independent molecules are discussed with respect to the potential of Schiff-base compounds of this type to serve as possible models for oxygen carriers in biological systems.

Oxidation of diamagnetic octa-µ3-chloro-octahedro-hexamolybdenum(II) and -tungsten(II) clusters to paramagnetic dodeca-µ2-chloro-octahedro-hexamolybdenum(3+) and -tungsten(III) clusters

Oxidation of tungsten dichloride, [W6Cl8, Cl4, with octachlorocyclopentene at 270 °C yields tungsten trichloride, W6Cl12]Cl6. This complex is paramagnetic, containing two unpaired electrons. Similar oxidation of molybdenum dichloride, [Mo6Cl8]Cl4, yields [Mo6Cl12]Cl3 in which the average oxidation state of molybdenum is +2·5. The salt (Et4N)3[(Mo6Cl12) Cl6] is also readily obtained.

Condensation of formaldehyde with chelated glycine and ethylenediamine: a new macrocycle synthesis; X-ray structures of [α-hydroxymethylserine-bis(ethylenediamine)cobalt(III)]2+ and [α-hydroxymethylserine-1,4,8,11-tetra-aza-6,13-dioxacyclotetradecanecobalt(III)]2+ ions

Condensation of formaldehyde with glycinatobis-(ethylenediamine)cobalt(III) ion yields in turn [α-hydroxymethylserinebis(ethylenediamine)cobalt(III)]2+ and the macrocycle [α-hydroxymethylserine-1,4,8,11-tetra-aza-6,13-dioxacyclotetradecanecobalt(III)]2+, the structures of which have been established by X-ray structural analysis.

Crystal structure of tris(NN-diethyldithiocarbamato)iron(IV) pentaiodide

The crystal structure of the title compound [Fe(S2CNEt2)3][I5], has been determined by X-ray diffraction at 295(1) K, being refined to a residual of 0.049 for 3 328 ‘observed’ reflections. Crystals are triclinic, space group P, a= 17.41(1), b= 10.197(9), c= 10.184(8)A, α= 74.71(6), β= 73.29(6), γ= 89.19(7)°, and Z= 2. The structure comprises [Fe(S2CNEt2)3]+ cations and I5– anions. Within the cation the symmetry is approximately D3 with six Fe–S distances ranging between 2.292(4) and 2.314(4)A.

Crystal structure of bis[(3-chloropyridine)mercury(I)] diperchlorate

The crystal structure of the title compound, has been determined by single-crystal X-ray diffraction methods. The structure was solved by conventional heavy atom methods, and refined by block-diagonal least squares to R 0·114 for 625 independent visually observed reflections. Crystals are monoclinic, space group C2/m, a= 16·49 ± 0·02, b= 22·92 ± 0·04, c= 5·04 ± 0·01 A, β= 92·4 ± 0·1°. There are four dimers per unit cell, the asymmetric unit being half a dimer. Hg–Hg is 2·487 A, and is approximately axially co-ordinated by the ligand (Hg–N 2·21 A, Hg–Hg–N 167·4°). There are two independent perchlorate ions in the cell.

Stereoselective chelate and amino-acid synthesis with chelated 2-iminopropionate; X-ray crystal and molecular structures of α-(N2-2-aminoethylamidino)alaninato-ONN″N‴-(ethylenediamine)cobalt(III) and α-(N2-2-aminoethylamidino)alanine-NN″N‴-(chloro)ethylenediaminecobalt(III) tetrachlorozincates

An intramolecular reaction follows the rapid addition of CN– at the imine centre of the bis(ethylenediamine)-2-iminopropionatocobalt(III) ion (1) where a deprotonated amine centre attacks the added CN group to give a quadridentate amidine with substantial stereospecificity; the crystal and molecular structures of the tetrachlorozincates of two inter-related complexes, α-(N2-2-aminoethylamidino)alaninato-ONN″N‴-(ethylenediamine)cobalt (4) and α-(N2-2-aminoethylamidino)alanine-NN″N‴-(chloro)ethylenediaminecobalt (6), have been determined.

Crystal structure of hexakis(triphenylphosphine oxide)dimercury(I) bisperchlorate

The title compound has been prepared and its crystal structure determined by single-crystal X-ray diffraction methods. The structure was solved by Patterson and Fourier methods and refined by block-diagonal least-squares methods to R 0·12 for 1696 independent visually estimated reflections. Crystals are triclinic, space group Pa= 12·55(1), b= 14·47(2), c= 16·05(2)A, α= 120·0(1), β= 82·3(1), γ= 95·2(1)°. There is one dimeric unit in the cell, the best formulation being [(Ph3PO)3Hg–Hg(Ph3PO)3][ClO4]2. Hg–Hg is 2·522(2)A. The centrosymmetric cationic species is discrete and the mercury environment approximately tetrahedral (Hg–O 2·29–2·43 A); there is an inverse correlation between the Hg–O distance and the Hg–Hg–O angle. The perchlorate ion is subject to high thermal motion and is ill-defined; the Ph3PO geometries are as expected.