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).

The mystery of the cerebellum: clues from experimental and clinical observations

Abstract The cerebellum has a striking homogeneous cytoarchitecture and participates in both motor and non-motor domains. Indeed, a wealth of evidence from neuroanatomical, electrophysiological, neuroimaging and clinical studies has substantially modified our traditional view on the cerebellum as a sole calibrator of sensorimotor functions. Despite the major advances of the last four decades of cerebellar research, outstanding questions remain regarding the mechanisms and functions of the cerebellar circuitry. We discuss major clues from both experimental and clinical studies, with a focus on rodent models in fear behaviour, on the role of the cerebellum in motor control, on cerebellar contributions to timing and our appraisal of the pathogenesis of cerebellar tremor. The cerebellum occupies a central position to optimize behaviour, motor control, timing procedures and to prevent body oscillations. More than ever, the cerebellum is now considered as a major actor on the scene of disorders affecting the CNS, extending from motor disorders to cognitive and affective disorders. However, the respective roles of the mossy fibres, the climbing fibres, cerebellar cortex and cerebellar nuclei remains unknown or partially known at best in most cases. Research is now moving towards a better definition of the roles of cerebellar modules and microzones. This will impact on the management of cerebellar disorders

CCDC 155933: Experimental Crystal Structure Determination

Related Article: F.T.Edelmann, J.-K.F.Buijink, S.A.Brooker, R.Herbst-Irmer, U.Kilimann, F.M.Bohnen|2000|Inorg.Chem.|39|6134|doi:10.1021/ic000219e,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Surface Organometallic Chemistry of Titanium: Synthesis, Characterization, and Reactivity of (Si-O)nTi(CH2C(CH3)3)4-n (n =1, 2) Grafted on Aerosil Silica and MCM-41

International audienceThe reaction of tetrakisneopentyl titanium, TiNp4 (1), with the surface of partially dehydroxylated Aerosil silica and MCM-41 and the reactivity of the resultant supported titanium alkyl product with water, alcohols, and oxygen are reported. Two methods of preparation have been investigated and compared for the grafting of TiNp4: (i) reaction of the support with the vapor of the sublimed complex and (ii) impregnation of the support with a solution of the complex. The second method appeared to be more reliable for “larger scale” preparations. The surface species thus obtained were characterized by infrared spectroscopy, solid state NMR, XAFS, elemental analysis, and various test reactions. Whereas on an Aerosil silica partially dehydroxylated at 500 °C, SiO2-(500), the surface complex is a monopodal titanium trisalkyl complex, SiO−Ti[CH2C(CH3)3]3, 2a, a bipodal titanium bisalkyl complex, (SiO)2Ti[CH2C(CH3)3]2, 2b, is obtained as the major species (ca. 65%) with 2a on MCM-41(500). The reason for this difference in behavior is discussed on the basis of the surface structure. The results obtained from hydrolysis confirmed the structure proposed for the supported alkyl complexes. For the reaction of the alkyl surface complexes with alcohols (MeOH, EtOH, tBuOH), the surface compounds obtained were characterized by the same techniques and by XPS and UV−vis. The results are consistent with the formation of monosiloxytrisalkoxy titanium complexes on SiO2-(500), SiO−Ti(OR)3, 3aOR, and of SiO−Ti(OtBu)3, 3aOtBu, and (SiO)2Ti(OtBu)2, 3bOtBu, on MCM-41(500), after reaction with tBuOH. The supported titanium alkyl, 2a, also reacts with oxygen, leading mainly to SiO−Ti[OCH2C(CH3)3]3, probably via an unstable surface compound such as SiO−Ti[OCH2C(CH3)3]2[OOCH2C(CH3)3], resulting from the incorporation of two molecules of oxygen in 2a