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Colin A Kilner

Publications and source records attributed to Colin A Kilner.

33 records · Page 2Linked to original sources
PubMed2003

Di-mu-hydroxo-bis([bis[2-(2-pyridyl)ethyl]amine-kappa 3N]copper(II)) dichloride hexahydrate.

The title compound, [Cu(2)(OH)(2)(C(14)H(17)N(3))(2)]Cl(2).6H(2)O, is a crystallographically centrosymmetric dimer of square-pyramidal Cu(II) centres, with a basal-basal [Cu(2)(mu-OH)(2)](2+) bridging motif and apical pyridyl donors. The Cl(-) anion is hydrogen bonded to one O-H and one N-H group, and to three different water molecules. Because of disorder, the network of intramolecular hydrogen bonding in the hydrated lattice is only partly resolved.

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PubMed2003

A crystallographic, EPR and theoretical study of the Jahn-Teller distortion in [CuTp2] (Tp- = tris[pyrazol-1-yl]hydridoborate).

Crystals of the title compound (1) contain two independent, centrosymmetric half-molecules per asymmetric unit. While both of these show Jahn-Teller elongated six-coordinate geometries, the lengths of the elongated Cu-N bonds in the two molecules differ by 0.117(2) A at 30 K. The structure of one of these molecules (molecule A) does not vary with temperature below 350 K. The other molecule (molecule B) shows Cu-N bond lengths that are temperature-dependent between 225 and 375 K, but do not vary further at lower temperature. This indicates a fluxional axis of Jahn-Teller elongation in this molecule at these higher temperatures. Consideration of the thermal parameters in these structures implies that the fluxionality in molecule B is frozen out near 150 K. This conclusion is supported by a Q-band powder EPR study. The d-d transition energies of molecules A and B have been calculated by several density function (DF) methods, including a time-dependent DF calculation. The crystallographic data have been reproduced using the vibronic coupling model of Burgi and Hitchman. This has shown that the different fluxionality regimes for molecules A and B are not a consequence of their different static molecular structures, but rather reflect their different local environments in the crystal.

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PubMed2003

Antisymmetric exchange in two tricopper(II) complexes containing a [Cu3(micro3-OMe)]5+ core.

Reaction of CuX2(X-=Cl- or Br-) with 2 molar equivalents of 3[5]-(2,4,6-trimethylphenyl)pyrazole (HpzMes) in MeOH in the presence of NaOH yields [Cu3X(HpzMes)2(micro-pzMes)3(micro3-OMe)]X (X-=Cl- or Br-). Crystal structures of these compounds show almost identical triangles of Cu(II) ions, centred by a triply bridging methoxide ligand and with three edge-bridging pyrazolide groups. The mesityl substituents on the bridging pyrazolide ligands are arranged in HT, HH, TT fashion. chi(M)T for both compounds decreases steadily with decreasing temperature, reaching 0.40 cm(3) mol(-1) K at 70 K before decreasing further below 40 K. This low temperature behaviour could not be interpreted using conventional superexchange Hamiltonians, but was reproduced by an alternative model that incorporated an additional antisymmetric exchange term. This interpretation was confirmed by the Q-band EPR spectra of the two compounds. NMR experiments show that the structures of these compounds are not retained in solution, in contrast to other closely related tricopper compounds. These are the first examples of triangular Cu(II) compounds bearing a [Cu3micro3-OR)]5+(R is not equal to H) core motif, and the first triangular compounds showing antisymmetric exchange to have been analysed by both susceptibility and EPR measurements.

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PubMed2003

(eta2-tetracyanoethene)bis(triphenylphosphine-kappaP)palladium-dichloromethane (1/0.7).

The title compound, [Pd(C(6)N(4))(C(18)H(15)P)(2)].0.7CH(2)Cl(2), shows a planar coordination geometry around the metal atom that is an almost perfect isosceles triangle if the tetracyanoethene (tcne) ligand is deemed to occupy a single coordination site. The framework of the tcne ligand shows small distortions due to intramolecular steric contacts between the C[triple-bond]N groups and phenyl rings of the triphenylphosphine ligands.

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PubMed2003

Hexa-mu-chloro-mu4-oxo-tetrakis[[5-(2,4,6-trimethylphenyl)pyrazole-kappaN2]copper(II)].

The title compound, [Cu(4)Cl(6)O(C(12)H(14)N(2))(4)], is a new example of the well known [Cu(4)(mu(4)-O)(mu-X)(6)L(4)] class of complex (X(-) is Cl(-), Br(-) or I(-), and L is a monodentate ligand). The molecule has crystallographic C(2) symmetry, with two Cl(-) ions on each edge of a Cu(4) tetrahedron. Two of these, on opposite edges of the tetrahedron, accept intramolecular hydrogen bonds from two of the pyrazole N-H donors.

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PubMed2002

Monocarbaborane anion chemistry. An interesting encapsulation of the Pd2I2(P(C6H(4)-4-Me)3)4]2+ cation by a pair of [PhCB9H4I(C6H4Me)4]- anions.

Reaction of the [1-Ph-closo-1-CB9H(4)-6,7,8,9,10-I5]- anion with 4-MeC6H4MgBr in the presence of [PdCl2(PPh3)2] gives the [Pd2I2(P(C6H(4)-4-Me)3)4]2+ salt of the [1-Ph-closo-1-CB9H(4)-10-I-6,7,8,9-(C6H(4)-4-Me)4]- anion, which exhibits an unusual neutral supramolecular assembly in the solid state, in which the dipalladium dication is encapsulated by two four-armed 'tetrapus' anionic units; the anion also has potentialities for four-fold dendrimer construction.

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PubMed2002

[2,6-Bis(3,5-dimethylpyrazol-1-ylmethyl)pyridine]iodocopper(I) dichloromethane solvate.

The title compound, [CuI(C(17)H(21)N(5))] x CH(2)Cl(2), contains a tetracoordinate Cu(I) centre with an unusual distorted tetrahedral stereochemistry, which has also been observed in other Cu(I) complexes containing this tridentate ligand. This distortion is probably a result of intermolecular steric contacts between the I(-) ligand and a neighbouring CH(2)Cl(2) molecule.

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PubMed2002

Tetrakis(5-tert-butylpyrazole-1kappaN2)tetrachloro-1kappaCl,2kappa3Cl-micro-oxo-1:2kappa2O-diiron(III).

The title compound, [Fe(2)Cl(4)O(C(7)H(12)N(2))(4)], contains vertex-sharing distorted tetrahedral [FeOCl(3)](-) and octahedral [FeOCl(Hpz(t)Bu)(4)](+) moieties (Hpz(t)Bu is 5-tert-butylpyrazole), linked by a bent oxo bridging ligand. The two Fe(III) centres are also bridged by intramolecular hydrogen bonds between the pyrazole N-H groups and the O(2-) and Cl(-) ligands.

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PubMed2002

3,4-(4-Methoxybenzo):8,9-benzobicyclo[4.4.1]undeca-3,8-dien-11-one ethylene acetal.

The title compound, 5-methoxyspiro[tetracyclo[8.8.1.0(3,8).0(12,17)]nonadeca-3,5,7,12,14,16-hexene-19,2'-[1,3]dioxolane], C(22)H(24)O(3), exhibits a twin-chair conformation with the aromatic rings overlying each other. Comparison of the dihedral angle between these two rings with those from previously reported [3.3]orthocyclophanes of this type suggests the presence of a weak attractive charge-transfer interaction between the two, different, stacked arenes.

Acetals↗
PubMed2001

Bis[2-(pyrazol-3-yl)phenolato-kappa2N2,O]copper(II) dimethanol solvate.

The title compound, [Cu(C9H7N2O)2]*2CH3OH, contains a crystallographically centrosymmetric near-regular square planar Cu(II) centre with trans-disposed chelating ligands. The complex molecules associate into a one-dimensional polymeric chain via hydrogen bonding to the solvent molecules.

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