Dianne D. Ellis

X-ray crystal structures, spectroscopic and magnetic measurements of copper(II) and cobalt(II) halide compounds with bis(2-benzimidazolyl)alkane ligands

Abstract Seven new Cu(II) and Co(II) coordination compounds are synthesised with the general formula M(L)(X)2(Y)z, in which L stands for the known ligand bis(2-benzimidazolyl)propane and for the novel ligands bis(2-benzimidazolyl)-2-butane and bis(2-benzimidazolyl)-3-butane, M=Cu(II) and Co(II), X=Cl and Br, Y=water and/or ethanol and z varies from 0 to 1. The single-crystal X-ray structural analyses as well as some spectroscopic and magnetic measurements have been performed. Each Cu(II) and Co(II) is surrounded by a didentate chelating ligand and two halide anions resulting in a distorted tetrahedral geometry with MN distances varying from 1.975 to 2.204 A and MCl distances from 2.215 to 2.268 A. Some structural data with these compounds are compared with related compounds in the literature.

A stereoselective route to medium-ring cis-1,n-dialkyl-1,n-diphosphacycloalkanes

Quaternisation of 1, (k+ 2)-diphosphabicyclo[k.1.0]alkanes 2, followed by treatment of the monoquaternary salts with alkyllithium or Grignard reagents produces the cis-isomers of 1,n-disubstituted-1,n-diphosphacycloalkanes 3 exclusively; examples containing eight-, nine- and ten-membered rings are described and the structures of two of these compounds 3a and 3f have been determined.

Chloro­bis­(tri­phenyl­phosphine)­nickel(I) tetra­hydro­furan solvate and an unsolvated trigonal phase of chloro­tris­(tri­phenyl­phosphine)­nickel(I)

In [NiCl(C(18)H(15)P)(2)].C(4)H(8)O, the Ni atom is coordinated by three ligands in a distorted trigonal-planar configuration, with a P-Ni-P angle of 111.52 (2) degrees. In [NiCl(C(18)H(15)P)(3)], there are three independent molecules in the asymmetric unit, with each Ni-Cl bond on a crystallographic threefold rotation axis. Each Ni centre is tetrahedrally bound. The Ni atoms in both compounds have a d(9) configuration and a formal oxidation state of Ni(I). A comparison is made between the form of [NiCl(PPh(3))(3)] presented here and that of a known toluene solvate.

Synthesis, characterisation and crystal structures of new nickel complexes in S4 coordination spheres; an unprecedented rearrangement during ligand synthesis

Two new nickel(II) complexes were synthesized with an S4 coordination environment. These complexes were synthesized by in situ deprotection of thiouronium salts in the presence of nickel(II). The ligands used are 4-mercapto-3,3-methyl-1-phenyl-2-thiabutane (Hbsms) and α,α′-bis(4-mercapto-3,3-methyl-2-thiabutyl)-o-xylene (H2xbsms). The former is a didentate ligand containing one thioether and one thiolate group and the latter is a dithioether dithiolate tetradentate ligand. The differences between these ligands upon coordination to nickel have been investigated. During the synthesis of these ligands, an unprecedented spontaneous rearrangement occurs, which is very fast and selective to a single product. The complexes were characterized by analytical, spectroscopic and electrochemical methods. The geometry of the nickel complexes is square planar according to the single-crystal X-ray structures. In [Ni(bsms)2] the two ligands are coordinated with the thiolates in trans positions towards each other; in [Ni(xbsms)] the thiolates are in enforced cis positions. [Ni(bsms)2] crystallizes in the triclinic space group P and has one centrosymmetric molecule in the unit cell. [Ni(xbsms)] crystallizes in the monoclinic space group P21/c with two independent molecules in the asymmetric unit, however, the differences between these two molecules are very small. The Ni–S distances are 2.1730(4)–2.1909(6) A and in the common range for thiolates and chelating thioethers.

Cobalt-Assisted Condensation of 2-Butanone Oxime and Acetone: Synthesis and X-ray Structure of the Novel Acetaldiimine Complex [CoI2{((CH3CH2)(CH3)C=NO)2C(CH3)2}]

The synthesis of the first acetaldiimine cobalt complex and its full characterisation are reported. The nitrogen-bonded chelate complex [CoI2{((CH3CH2)(CH3)C=NO)2C(CH3)2}] is obtained in high yield from the reaction of 2-butanone oxime with cobalt iodide dihydrate in acetone, in the presence of trimethyl orthoformate as dehydrating agent. A single-crystal X-ray structure determination, infrared spectroscopy and mass spectrometry analyses confirm the formation of a new ligand in situ from the addition of an acetone molecule to two oximato species. This cobalt-mediated reaction provides an indirect proof for the existence in solution of monodentate N-bonded cobalt−ketoxime species.

Silsesquioxane-bonded zirconocene complexes; soluble models for silica-tethered olefin polymerization catalysts

Silsesquioxane tethered fluorene ligands [R7Si8O12X]-9-Flu(H) (R = c-C6H11, X = – (1); R = c-C5H9, X = CH2 (2), (CH2)3 (3), C6H4CH2 (4)), (c-C5H9)7Si8O12CH2-9-Flu(9-EMe3) (E = Si (5a), Sn (5b)) and zirconium dichlorides Cp″[(c-C5H9)7Si8O12CH2-9-Flu]ZrCl2 (6b, Cp″ = 1,3-C5H3(SiMe3)2), Cp*[(c-C5H9)7Si8O12-X-9-Flu]ZrCl2 (X = CH2 (6a), (CH2)3 (7), C6H4CH2 (8)) and [(c-C5H9)7Si8O12CH2-9-Flu]2ZrCl2 (9) have been applied as models for silica-tethered ancillary ligands and silica tethered-zirconocenes. Immobilization of zirconocenes containing a pendant anchorable functionality, Cp″[Me2(EtO)SiCH2Flu]ZrCl2 (10) and Cp[C5Me4SiMe2OEt]ZrCl2 (11) was considerably hampered by competitive Zr–Cl and Si–OEt bond splitting. When activated with MAO (methylalumoxane), 6–9 yield active ethylene polymerization systems.

cis-Bis[N1,N2-bis(trimethylsilyl)benz­amidinato-κ2N1,N2]chloro(4-tolyl­imido-κN)vanadium(V)

The title complex, [V(C 7 H 7 N)(C 13 H 23 N 2 Si 2 ) 2 Cl] consists of a V metal centre coordinated to five N atoms and a Cl - ion in a pseudo-octahedral arrangement. The N atoms of the benzamidinate ligands form two four-membered chelate rings to V, with bite angles of 63.59 (8) and 64.36 (8)°, whilst the fifth N atom is from a p-tolylimido ligand [V-N-C 172.2 (2)°] located cis with respect to the Cl - ion [Cl-V-N imido 96.96 (8)°].

Zwitterionic pyrrolidine-2,2-diylbis(phosphonic acid) at 100, 150 and 293 K

The title compound, C4H11NO6P2, reveals a two-dimensional network of P—O—H⋯O=P and N—H⋯O=P hydrogen-bond interactions, forming molecular slabs parallel with the (010) plane. One O—H⋯O interaction is distinct within these sets: whilst forming the shortest intermolecular hydrogen bond, it possesses a short P—O(H) bond of 1.5291 (10) A. Weak C—H⋯O contacts link individual stacks to produce a three-dimensional array. The compound is zwitterionic: one H atom from a P—O—H group has transferred to the pyrrolidine ring N atom.

Tetrakis­(tri­phenyl­phosphine)silver(I) tetra­phenyl­borate aceto­nitrile solvate

In the title compound, [Ag{P(C6H5)}4][B{P(C6H5)}4]·CH3CN, the Ag ion resides on a crystallographic twofold rotation axis and is tetrahedrally coordinated. There is a disparity between the two independent Ag—P distances. This is due, in part, to the temperature differences (all previous determinations are at room temperature) but also to the packing effects of various anions.

Unique chains of alternating octahedral and tetrahedral cobalt(II) sites: crystal structures of the novel chloro-bridged complexes [Co4(μ-Cl)6Cl2(thf)4(MeOH)2]n and [{Co4(μ-Cl)6Cl2(thf)4(H2O)2}·2THF]n

[Co4(μ-Cl)6Cl2(thf)4 (MeOH)2]n, a catena-polycobalt(II) complex with an unusual linear chain of octahedral/tetrahedral/octahedral cobalt sites, is obtained quantitatively from the reaction between cobalt chloride hydrate and trimethylorthoformate in THF.