Vanadium (β-(Dimethylamino)ethyl)cyclopentadienyl Complexes with Diphenylacetylene Ligands

Reduction of the V(III) (β-(dimethylamino)ethyl)cyclopentadienyl dichloride complex [η5:η1-C5H4(CH2)2NMe2]VCl2(PMe3) with 1 equiv of Na/Hg yielded the V(II) dimer {[η5:η1-C5H4(CH2)2NMe2]V(µ-Cl)}2 (2). This compound reacted with diphenylacetylene in THF to give the V(II) alkyne adduct [η5:η1-C5H4(CH2)2NMe2]VCl(η2-PhC≡CPh). Further reduction of 2 with Mg in the presence of diphenylacetylene resulted in oxidative coupling of two diphenylacetylene groups to yield the diamagnetic, formally V(V), bent metallacyclopentatriene complex [η5:η1-C5H4(CH2)2NMe2]V(C4Ph4).

A highly efficient titanium-based olefin polymerisation catalyst with a monoanionic iminoimidazolidide pi-donor ancillary ligand

The titanium complex Cp[1,3-(2',6' Me2C6H3) (2)(CH2N)(2)C=N] Ti(CH2Ph)(2), with a monoanionic eta(1)-iminoimidazolidide ancillary ligand, is shown to be a highly efficient catalyst for olefin polymerisation when activated with the Lewis acid B(C6F5)(3)

First-row transition metal bis(amidinate) complexes; Planar four-coordination of Fe-II enforced by sterically demanding aryl substituents

The sterically hindered benzamidinate ligand [PhC(NAr)(2)](-) (Ar = 2,6-iPr(2)C(6)H(3)) has been employed to prepare bis(amidinate) complexes [{PhC(NAr)(2)}(2)M] of the divalent first-row transition metals Cr-Ni (1-5). For Cr (planar), Mn and Co (tetrahedral) the observed structures follow the electronic preference for the metal ion in its highest spin multiplicity, as determined by DFT calculations. Remarkably, the Fe derivative adopts a distorted planar structure while retaining the high-spin (S = 2) configuration. This rare combination due to reduced interligand steric interactions in the planar vs. the tetrahedral structure, combined with a relatively small electronic preference of Fen for the tetrahedral environment. Thus, the simple bidentate ligand N,N '-diarylbenzamidinate provides a convenient means to make this unusual species accessible for further study. (c) Wiley-VCH Verlag GmbH & Co

Diffraction Symmetry in Crystalline, Close-Packed C60

We have grown crystals of the carbon structure C60 by sublimation. In contrast to solution-grown crystals, the sublimed crystals have long range order with no evidence of solvent inclusions. Sublimed C60 forms three dimensional, faceted crystals with a close-packed, face-centered cubic unit cell. We have refined a crystal structure using the "soccer ball" model of the C60 molecule. The results indicate that the C60 molecule has the expected spherical shape, however the data are not sufficiently accurate to unambiguously determine atomic positions

A Reduced Neodymium Titanate with a New Intergrowth Structure Type

Single crystals of a new reduced neodymium titanate, Nd3Ti4O12 , have been obtained by slow cooling of a reduced Nd–Ti–O ceramic precursor in a molten neodymium borate flux under high vacuum. Single crystal X-ray diffraction (space group Pcmn, a = 5.420(1) Å, b = 7.610(1) Å, c = 22.015(5) Å, Z = 4, Pearson symbol oP76) showed that the structure of Nd3Ti4O12 is built from an arrangement of corner-sharing and edge-sharing TiO6-octahedra that can be considered as a regular intergrowth of the GdFeO3 and CaTa2O6 structure types. The material is nonmetallic (R(25°C) = 35 Ωcm) which may arise due to the localization of the Ti 3d-electrons in the edge-sharing pairs of TiO6-octahedra (short Ti–Ti distance of 2.760(3) Å)