Synthesis and Characterization of Novel Cobalt Carbonyl Phosphorus and Arsenic Clusters.

Phosphorus- and arsenic-containing cobalt clusters are an interesting class of compounds that continue to provide new structures with captivating bonding patterns. Although the first members of this family were reported 45 years ago, the number of such species is still limited within the broad family of transition metal complexes bearing pnictogen atoms. Herein, we present the reaction of Co(CO) as a cobalt source with a number of phosphorus- and arsenic-containing compounds under variable reaction conditions.

Conversion of E (E =P , As , AsP ) by Ni(0) and Ni(I) Synthons - A Comparative Study.

The reactivity of white phosphorus and yellow arsenic towards two different nickel nacnac complexes is investigated. The nickel complexes [(L Ni) tol] (1, L =[{N(C H Pr -2,6)C(Me)} CH] ) and [K ][(L Ni) (μ,η -N )] (6) were reacted with P , As and the interpnictogen compound AsP , respectively, yielding the homobimetallic complexes [(L Ni) (μ-η ,κ :η ,κ -E )] (E=P (2 a), As (2 b), AsP (2 c)), [(L Ni) (μ,η -E )] (E=P (3 a), As (3 b)) and [K@18-c-6(thf) ][L Ni(η -E )] (E=P (7 a), As (7 b)), respectively. Heating of 2 a, 2 b or 2 c also leads to the formation of 3 a or 3 b.

Iron β-diiminate complexes with As-, As- and As-ligands.

Different substituents at the β-diiminato ligand in low-valent [LFe(tol)] (L = β-diiminato) complexes fundamentally change their reactivity towards yellow arsenic. By using dmp (2,6-dimethylphenyl) as flanking groups, the tetranuclear complexes [(LFe)As] (L = L (1), L (2)) are isolated. For dipp (2,6-diisopropylphenyl) substituted ligands, dinuclear complexes [(LFe)(cyclo-As)] (L = L (3a), L (4a)) are obtained.

Element-Element Bond Formation upon Oxidation and Reduction.

The redox chemistry of [(Cp'''Co) (μ,η :η -E ) ] (E=P (1), As (2); Cp'''=1,2,4-tri(tert-butyl)cyclopentadienyl) was investigated. Both compounds can be oxidized and reduced twice. That way, the monocations [(Cp'''Co) (μ,η :η -E )][X] (E=P, X=BF (3 a), [FAl] (3 b); E=As, X=BF (4 a), [FAl] (4 b)), the dications [(Cp'''Co) (μ,η :η -E )][TEF] (E=P (5), As (6)), and the monoanions [K(18-c-6)(dme) ][(Cp'''Co) (μ,η :η -E )] (E=P (7), As (8)) were isolated.

The Influence of β-diiminato Ligands on As Activation by Cobalt Complexes.

In a systematic study of the activation of As , three [LCo(tol)] (L=β-diiminato) complexes have revealed different steric and electronic influences. 2,6-Diisopropylphenyl (Dipp) and 2,6-dimethylphenyl (dmp) flanking groups were used, one of the ligands with H backbone substituents (β-dialdiminate L ) and two with Me substituents (β-diketiminates L and L ). In the reaction with As , different dinuclear products [(LCo) As ] (LM=L (1), L (2), L (3)) were isolated, with all showing differently shaped [Co As ] cores in the solid state: octahedral in 1, prismatic in 2, and asterane-like in 3.

Nacnac-Cobalt-Mediated P Transformations.

A comparison of P activations mediated by low-valent β-diketiminato (L) cobalt complexes is presented. The formal Co source [K (L Co) (μ :η ,η -N )] (1) reacts with P to form a mixture of the monoanionic complexes [K(thf) ][(L Co) (μ :η ,η -P )] (2) and [K(thf) ][(L Co) (μ :η ,η -P )] (3). The analogue Co precursor [L Co(tol)] (4 a), however, selectively yields the corresponding neutral derivative [(L Co) (μ :η ,η -P )] (5 a).

Influence of the nacnac Ligand in Iron(I)-Mediated P4 Transformations.

A study of P4 transformations at low-valent iron is presented using β-diketiminato (L) Fe(I) complexes [LFe(tol)] (tol=toluene; L=L(1) (1 a), L(2) (1 b), L(3) (1 c)) with different combinations of aromatic and backbone substituents at the ligand. The products [(LFe)4 (μ4 -η(2) :η(2) :η(2) :η(2) -P8 )] (L=L(1) (2 a), L(2) (2 b)) containing a P8 core were obtained by the reaction of 1 a,b with P4 in toluene at room temperature. Using a slightly more sterically encumbered ligand in 1 c results in the formation of [(L(3) Fe)2 (μ-η(4) :η(4) -P4 )] (2 c), possessing a cyclo-P4 moiety.

Versatile structures of group 13 metal halide complexes with 4,4'-bipy: from 1D coordination polymers to 2D and 3D metal-organic frameworks.

A systematic structural study of complexes formed by aluminium and gallium trihalides with 4,4'-bipyridine (bipy) in 2 : 1, 1 : 1, and 1 : 2 stoichiometric ratios has been performed. Molecular structures of 11 complexes in the solid state have been determined for the first time. Complexes of 2 : 1 composition are molecular, while complexes of 1 : 1 composition form metal-organic frameworks of different kinds: an ionic 3D network (three interpenetrated lvt nets for AlCl3bipy), an ionic 2D network for AlBr3bipy and GaBr3bipy and a 1D coordination polymer in the case of GaCl3bipy.

Do solid-state structures reflect Lewis acidity trends of heavier group 13 trihalides? Experimental and theoretical case study.

Lewis acidity trends of aluminum and gallium halides have been considered on the basis of joint X-ray and density functional theory studies. Structures of complexes of heavier group 13 element trihalides MX(3) (M = Al, Ga; X = Cl, Br, I) with monodentate nitrogen-containing donors Py, pip, and NEt(3) as well as the structure of the AlCl(3)·PPh(3) adduct have been established for the first time by X-ray diffraction studies. Extensive theoretical studies (B3LYP/TZVP level of theory) of structurally characterized complexes between MX(3) and nitrogen-, phosphorus-, arsenic-, and oxygen-containing donor ligands have allowed us to establish the Lewis acidity trends Al > Ga, Cl ≈ Br > I.

Reciprocal interactions between MK-801, sleep deprivation and recovery in modulating rat behaviour.

Increasing evidence indicates that sleep deprivation alters behavioural responses to various pharmacological agents which might be associated to changes in receptor systems. The present work addressed the effects of sleep deprivation and recovery on behavioural changes induced by MK-801, and investigated whether such effects are related to changes in NMDA receptor (NMDAR) binding. Male Wistar rats were deprived of sleep for 96 h using the platform method (SD group), or were sleep deprived and then allowed to recover sleep for 24 h (SR group).

Ethanol-induced behavioral sensitization is associated with dopamine receptor changes in the mouse olfactory tubercle.

Accumulating evidence points to the mesolimbic and the nigrostriatal dopamine systems as critical to behavioral sensitization induced by several drugs of abuse. In the present study, we analyzed D1 and D2 binding to brain regions related to these dopaminergic systems during the expression of ethanol-induced behavioral sensitization. The first experiment was performed to demonstrate the effectiveness of the ethanol treatment schedule and challenge used to induce the expression of the behavioral sensitization phenomenon.

Beneficial effects of vitamin C and vitamin E on reserpine-induced oral dyskinesia in rats: critical role of striatal catalase activity.

Oral dyskinesias are implicated in a series of neuropathologies and have been associated to an increase in oxidative stress. Several antioxidants, including vitamin E, decrease reserpine-induced oral dyskinesia (OD) in rodents and we have described a protective role of striatal catalase against the development of OD. The aim of this study was to verify the effects of vitamin C alone or in combination with vitamin E on reserpine-induced OD as well as to determine a possible role of catalase in the antidyskinetic property of these vitamins.