Synthesis Of Cp Research Articles

Synthesis, structural characterization, and reactivity of Cp*Ru(N-phosphinoamidinate) complexes

We report herein on the synthesis and spectroscopic/crystallographic characterization of the first isolable, formally 16-electron Cp*Ru(κ2-P∼N) species, which are supported by N-phosphinoamidinate ligands. Despite the stability of such complexes, they have been shown to readily coordinate two-electron (L) donors including carbon monoxide and 2,6-xylylisocyanide, affording crystallographically characterized 18-electron Cp*Ru(L)(κ2-P∼N) adducts. Preliminary reactivity studies confirm that such complexes are capable of extruding hydrogen from ammonia borane.

Acute and subacute response of iron, zinc, copper and selenium in pigs experimentally infected with Actinobacillus pleuropneumoniae.

This study was performed to characterise the response of iron (Fe), zinc (Zn), copper (Cu) and selenium (Se) in bacterial-induced porcine acute phase reaction (APR). Twenty piglets were challenged by aerosolic infection with Actinobacillus pleuropneumoniae (A.pp.) serotype 2, ten piglets serving as controls. Blood sampling was done initially and at day 4 and 21 after infection, collection of liver tissue was done at day 21 (autopsy). A.pp.-infection caused fever and respiratory symptoms. APR at day 4 after infection was marked by an increase in total white blood cells, granulocytes and monocytes in whole blood samples and an increase in globulin/albumin ratio (G/A), α2-globulins, C-reactive protein, haptoglobin, ceruloplasmin (Cp), Cu and Se in serum. Concurrently, there was a decrease in haemoglobin (Hb) and packed cell volume (PCV) in whole blood as well as a decrease in albumin, transferrin, total iron binding capacity and Fe in serum and Zn in plasma. The subacute stage at day 21 was characterised by progressively increased concentrations of G/A, β-globulins and γ-globulins reflecting the specific immune reaction. Hb and PCV showed further decreases, all other parameters returned to the initial concentrations. Glutathione peroxidase activity in plasma and liver tissue remained unaffected by A.pp.-infection. The liver concentration (day 21) of Zn was found to be higher, that of Se was lower in the A.pp.-group, whereas hepatic concentrations of Cu and Fe were not affected by A.pp.-infection. In summary, the acute and subacute stages of A.pp.-infection were accurately characterised by the APR-related parameters. Se was only marginally affected by the A.pp.-infection. The elevated plasma Cu concentration may be a side effect of the transient hepatic induction of Cp synthesis. Zn responded, being distinctly reduced in plasma and probably having been sequestered in the liver tissue. Reduction in serum Fe can be regarded as an unspecific defence mechanism in A.pp.-infection to withdraw Fe from bacterial acquisition systems.

Influence of the Torsion Angle in 3,3′-Dimethyl-2,2′-bipyridine on the Intermediate Valence of Yb in (C5Me5)2Yb(3,3′-Me2-bipy)

The synthesis and X-ray crystal structures of Cp*2Yb(3,3′-Me2bipy) and [Cp*2Yb(3,3′-Me2bipy)][Cp*2YbCl1.6I0.4]*CH2Cl2 are described. In both complexes, the NCCN torsion angles are approximately 40°. The temperature-independent value of nf of 0.17 shows that the valence of ytterbium in the neutral adduct is multiconfigurational, in reasonable agreement with a CASSCF calculation that yields a nf value of 0.27; that is, the two configurations in the wave function are f13(π*1)1 and f14(π*1)0 in a ratio of 0.27:0.73, respectively, and the open-shell singlet lies 0.28 eV below the triplet state (nf accounts for f-hole occupancy; that is, nf = 1 when the configuration is f13 and nf = 0 when the configuration is f14). A correlation is outlined between the value of nf and the individual ytterbocene and bipyridine fragments such that, as the reduction potentials of the ytterbocene cation and the free x,x′-R2-bipy ligands approach each other, the value of nf and therefore the f13:f14 ratio reaches a maximum; conversely, the ratio is minimized as the disparity increases.

Structural diversity in tris(cyclopentadienyl) complexes of the Group 4 metals: Synthesis of Cp and MeCp complexes of Zr and Hf, and crystallographic characterization of (MeCp)3HfCl and (MeCp)4Zr (MeCp = C5H4CH3)

Previous theoretical studies have predicted structural differences between the tris(cyclopentadienyl) zirconium and hafnium complexes Cp3MX (Cp=C5H5; M=Zr, Hf). Cp3ZrCl can be isolated via the stoichiometric reaction of Cp2ZrCl2 and NaCp, but forming the analogous Hf complex is complicated by ligand redistribution. Partial crystallographic analysis of these two complexes indicates likely structural differences wherein the Zr complex has three η5 Cp ligands (“3-5” structure) while the Hf complex has two η5 Cp ligands and one η1 Cp ligand (“2-5,1-1” structure). The use of C5H4CH3 (MeCp) simplifies both the syntheses and the procurement of suitable crystals. The preparation of a number of MeCp complexes of Zr and Hf is reported along with crystallographic characterization of (MeCp)3HfCl, which has a 2-5,1-1 structure and (MeCp)4Zr, which has a 3-5,1-1 structure.

Synthesis, Structural Characterization, and Reactivity of Cp2- and (CpMe)2-Ligated Titanaaziridines and Titanaoxiranes with Fast Enantiomer Interconversion Rates

A new synthetic route to (CpR)2-ligated titanaaziridines and titanaoxiranes from stable Ti(II) precursors has been developed, and the enantiomer interconversion rate constants for chiral titanaaziridines and titanaoxiranes have been measured for the first time. The titanaaziridines (CpR)2Ti(η2-N(R1)CHPh)(L) (R = H (10), Me (12); R1 = Ph (a), o-anisyl (b), SiMe3 (c); L = PMe3 (a, c), −OMe (b)) and titanaoxiranes Cp2Ti(η2-Ph(R)CO)(L) (R = Ph (14), H (15); L = PMe3) have been synthesized and characterized spectroscopically; titanaaziridine 10a and titanaoxirane 14 have been characterized by X-ray crystallography. The enantiomer interconversion rate constants for the chiral titanaaziridines and titanaoxiranes have been measured by variable-temperature NMR; kinv for 10b is the fastest enantiomer interconversion rate constant reported for any metallaaziridine or metallaoxirane to date. Titanaaziridines 10 and 12 undergo exchange reactions with C═C and C═X bonds, whereas the titanaoxiranes 14 and 15 undergo insertions.

The Study of Dimethyl Maleate CP Synthesis by Strong Acid Cation Type in Chemical Engineering

The catalytic distillation synthesis of Dimethyl maleate CP by methanol and maleic acid is studied under the application of strong acid cation type catalyst in chemical engineering.. The sulfonic resin catalyst is chosen. The reaction of methanol and maleic acid is single one, while that of mono-methyl fumarate chloride and methanol is the reversible reaction balance. The pilot of catalytic distillation synthesis of Dimethyl maleate CP is issued. The best condition for synthesis is proposed

Serúlópasmín og járn. Tengsl við Alzheimersjúkdóm og Parkinsonsjúkdóm

Ceruloplasmin, a multi-copper oxidase with four active copper atoms, oxidizes Fe2+ to Fe3+ and concomittantly fully reduces oxygen to water. The oxygenation of iron is a requisite for transferrin transport of iron and keeping noxious Fe2+ low. In the central nervous system (CNS) Cp is mostly localized in end feet of astrocytes surrounding capillaries and attached by a glycosylphosphatidylinositol-anchor. In aceruloplasminaemia, a rare recessive hereditary disease, complete loss of Cp is accompanied by disorders of iron metabolism and lesions in CNS and outside. In PD Cp concentration and oxidative activity in serum are significantly lowered with iron deposits and lesions in substantia nigra and basal ganglia. Changes in Cp-genes might be causative in these disorders. By inducing neuromelanin synthesis Cp may protect neurons in substantia nigra. In AD Cp activity in serum, but not concentration, is significantly lowered. Changes in Cp-genes have not been verified in AD. Total amounts of iron are not increased in AD brains although iron deposits and cortical lesions are numerous. Total copper is significantly lowered in AD brains. This may result in defective synthesis of Cp and other copper enzymes. - In conclusion, the defective Cp activity, associated with iron disorders, is seemingly of importance in PD and also in AD with other copper enzyme defects possibly involved.

Demethylation of the SMe2 substituent in metallacarboranes. Synthesis and structures of the complexes Cp*M(η-9-SMe-7,8-C2B9H10) (M = Rh, Ir)

The demethylation of the cations [Cp*M(η-9-SMe2-7,8-C2B9H10)]+ (1a,b) with PhCH2SNa affords neutral metallacarboranes Cp*M(η-9-SMe-7,8-C2B9H10) (2a: M = Rh; 2b: M = Ir). The reverse reaction can be performed by the treatment of complexes 2a,b with MeI in the presence of TlPF6. The structures of complexes 2a,b were determined by X-ray diffraction.

Ceruloplasmin and iron in Alzheimer’s disease and Parkinson’s disease: a synopsis of recent studies

Ceruloplasmin (Cp) concentration and oxidative activity in serum are lowered in Parkinson’s disease (PD). In most PD patients, iron increases in the substantia nigra in the midbrain. In PD, the low Cp concentration and activity in serum and the high iron amounts in the substantia nigra appears to be correlated. An hereditary background is common in PD and variations in the Cp gene that have been found in PD are associated with high iron levels in the substantia nigra. Variations in Cp synthesis and in the incorporation of copper into the Cp molecule are essential features of PD. In Alzheimer’s disease (AD), the Cp activity in serum is lowered but not the concentration, except in the advanced stages of the disease. Generally, iron is not increased in the AD brain. In the AD brain, iron accumulates in neuritic plaques and in neurofibrillary tangles. There is also increased risk of iron-mediated tissue damage, which may possibly be counteracted by Cp. At the same time, the AD brain is short in copper, which presumably results in the deficient activity of many copper enzymes in the brain, in addition to Cp. Lowered Cp activity in serum most likely stems from lessened incorporation of copper in the Cp molecule and similar incorporation defects might also apply to other copper enzymes in AD.

Effects of alfalfa silage storage structure and roasting corn on ruminal digestion and microbial CP synthesis in lactating dairy cows

The objective of this experiment was to quantify the effects of unroasted or roasted ground-shelled corn (GSC), when fed with alfalfa ensiled in bag, bunker, or O2-limiting tower silos on ruminal digestion and microbial CP synthesis in lactating dairy cows. The roasted corn was heat-treated in a propane-fired roasting system. Alfalfa was harvested as second cutting from fields with regrowth of the same maturity. A portion of each field was allotted to each silo. The diets with 3 × 2 factorial arrangement of treatments were fed to six multiparous rumen-cannulated Holstein cows in a cyclic change-over design with five 21-day periods. Experimental diets were comparable and averaged (on dry matter (DM) basis): 410 g/kg alfalfa silage (AS), 150 g/kg corn silage, 350 g/kg GSC, 50 g/kg soybean meal, 40 g/kg roasted soybeans, 177 g/kg CP, 264 g/kg NDF and 250 g/kg starch. Nutrient flow was quantified by the omasal sampling technique with use of three markers (Co, Yb and indigestible NDF). Continuous infusion of 10% atom excess (15NH4)2SO4 was used to label microbial CP. None of the interactions between storage structure of dietary AS and corn type were significant. DM intake was not different among dietary treatments, averaging 24.5 kg/day across diets. Means of ADF digested in the rumen for cows fed diets with AS from bag, bunker and O2-limiting tower silo were 2.1, 1.7 and 2.1 kg/day, respectively, and was lower in cows fed AS from the bunker silo. This response may partly be a reflection of the higher intake of ADF by cows fed AS ensiled in the O2-limiting tower silo compared with the bunker. There was a slightly greater supply of fermentable substrates for cows fed diets with roasted compared with unroasted GSC. The small increases in yield of milk protein and lactose observed in the previous production trial in cows fed diets containing roasted corn may have occurred because of greater supply of fermentable substrates.

Modulating the Steric, Electronic, and Catalytic Properties of Cp* Ruthenium Half-Sandwich Complexes with β-Diketiminato Ligands

Five different types of β-diketiminate ligands, bearing electron-donating to strongly electron-withdrawing substituents, were synthesized and used in the synthesis of Cp* ruthenium complexes (Cp* = η5-C5Me5). One series consists of complexes with a covalent RuIII–Cl bond, and the other series features a reduced RuII center, where the chloride is abstracted by treatment of the corresponding RuIII compounds with Zn or Mg. All compounds were characterized by single-crystal X-ray diffraction, UV–visible spectroscopy, and cyclic voltammetry. In the case of RuII complexes, solution NMR techniques provided key information regarding the electronic and structural differences induced by the different β-diketiminate ligands employed. Capitalizing on the facile reduction–oxidation cycle of the Cp* ruthenium β-diketiminato complexes, catalytic atom transfer radical addition (ATRA) and cyclization (ATRC) reactions were performed on relevant substrates. The turnover rates are strongly dependent on the type of β-diketimi...

Uranium(IV) Nucleophilic Carbene Complexes

The mono-, bis-, and tris-carbene uranium complexes [Li(THF)2U(SCS)Cl3(THF)] (2a), [U(SCS)2(THF)2] (3a), and [{Li(OEt2)}2U(SCS)3] (1) were synthesized in good yields by reactions of UCl4 and the stoichiometric amount of Li2(SCS) [(SCS)2– = [Ph2P(═S)]2C2–]. Complex 3a was also obtained by comproportionation reaction of 1 and 0.5 molar equiv of UCl4 and further reacted with 1 molar equiv of UCl4 to give the neutral mono-carbene [U(SCS)Cl2(THF)2] (5a). Treatment of U(NEt2)4 with H2C(Ph2PS)2 in THF led to a mixture of 3a and [U(SCS)(NEt2)2] (6), while the same reaction in Et2O gave the mixed alkyl-carbene compound [U(SCS)(SCHS)(NEt2)] (7) in 85% yield. The cationic uranium carbene complex [U(SCS)(NEt2)(THF)3][BPh4] (9) was isolated in almost quantitative yield from reaction of [U(NEt2)3][BPh4] and H2C(Ph2PS)2. Mono-carbenes 2a, 5a, and 9 were used as precursors for the synthesis of Cp and COT derivatives (Cp = C5H5, COT = C8H8). Treatment of 2a with 1 or 2 molar equiv of TlCp gave [Tl{U(Cp)(SCS)}2(μ-Cl)3] (10) and [U(Cp)2(SCS)] (11) in 90% and 79% yield, respectively, whereas [U(Cp*)2(SCS)] (12) (Cp* = C5Me5) was obtained only by reaction of [U(Cp*)2Cl2] and Li2(SCS). Reactions of 5a or 9 with K2COT gave [U(COT)(SCS)(THF)] (13) in 78% and 99% yield, respectively. 2a, [Li(THF)(Et2O)U(SCS)(μ-Cl)3]2 (2b), [U(SCS)2(py)2]·1.5py·0.5THF (3b·1.5py·0.5THF), [U(SCS){CS(Ph2PS)2}(py)] (4), 7·toluene, [Li(THF)2U(SCS)(NEt2)(μ-O)]2 (8), 10·2toluene, 11, 12, and 13·0.5pentane were characterized by X-ray diffraction. The crystal data revealed that, in contrast to transition metal complexes, changes in the coordination sphere of the U(IV) center have little influence on the U═C bond. This feature was explained by DFT analysis of analogous U(IV) and Zr(IV) compounds [M(SCS′)Cl2(py)2] and [M(SCS′)(Cp)2] [M = U, Zr; SCS′ = C(H2PS)2]. Although the 5f orbitals are more radially contracted than the 6d atomic orbitals, the 5f AOs are lower in energy in uranium and can lead to greater angular overlaps in symmetry-constrained systems. As a result, the seven 5f orbitals play a “buffer” role by engaging in covalent interactions with the carbon center to stabilize the nucleophilic carbene lone pairs.

Synthesis of Cp*2Ti(OTf) and Its Reaction with Water

AbstractCp*2Ti(OTf) (2) was prepared by oxidation of the known(alkyne)titanocene complex Cp*2Ti(η2‐Me3SiC2SiMe3) with Fe(OTf)3. This reaction is highly selective; formation of Cp*2Ti(OTf)2 by using an excess of the oxidizing agent was not observed. Complex 2 was treated with water to give Cp*2Ti(OH)(OTf) (5) and hydrogen gas. This reaction was monitored by GC and volumetric analysis. Complexes 2 and 5 were characterized by X‐ray crystallography and investigated by DFT analysis.

Influence of urea calcium mixture supplementation on ruminal fermentation characteristics of beef cattle fed on concentrates containing high levels of cassava chips and rice straw

The purpose of this study was to evaluate the effects of various N sources in concentrates containing high levels of cassava chips, with rice straw as the basal forage, on rumen ecology, rumen microbial counts, microbial crude (CP) protein synthesis, and digestibility of nutrients. Four ruminally fistulated crossbred (Brahman × native) beef steers with initial body weight (BW) of 400 ± 40.2 kg were randomly assigned according to a 4 × 4 Latin square design. The dietary treatments were different sources of N in the concentrates and were: T1 = urea (control; urea); T2 = soybean meal (SBM); T3 = urea CaCl 2 mixture (U-Cal); T4 = urea CaSO 4 mixture (U-Cas). All steers were kept in individual pens and supplemented with concentrate at 5 g/kg of BW daily. The experiment was 4 periods, and each lasted 21 d. During the first 14 d, all steers were fed their respective diets ad libitum and for during the last 7 d, they were moved to metabolism crates for total urine and fecal collection. Dry matter intake ranged from 9.8 to 10.5 kg daily and was not altered by diet, while digestibility of NDF differed among treatments and was highest with U-Cas supplementation (P<0.05). Ruminal NH 3 N and plasma urea N with U-Cal, U-Cas, and SBM diets were lower compared with the urea supplemented group (P<0.05). Ruminal volatile fatty acid concentrations were not altered by treatments. Total viable, and cellulolytic bacteria, differed among treatments and were highest with U-Cas (9.1 × 10 11, and 4.0 × 10 9 cfu/mL, respectively). In addition, efficiency of rumen microbial CP synthesis based on organic matter (OM) truly digested in the rumen was increased by SBM or U-Cal supplementation, and was highest with U-Cas supplementation (18.2 g of N/kg of OM truly digested in the rumen). Supplementation of U-Cas to a concentrate containing a high level of cassava chips improved rumen ecology and microbial CP synthesis in beef cattle, suggesting that urea calcium mixtures can replace soybean meal or urea in beef cattle diets without adverse affects on rumen fermentation and other rumen parameters.

Interleukin-1β induces ceruloplasmin and ferroportin-1 gene expression via MAP kinases and C/EBPβ, AP-1, and NF-κB activation

Previously, we demonstrated that IL-1β was able to increase iron efflux from glial cells through a coordinate induction of both ferroportin-1 (Fpn) and ceruloplasmin (Cp) synthesis. In this study, we have investigated the signaling pathways that are involved in the transcriptional activation of the Cp and Fpn. Our data show that the expression of Cp and Fpn in response to IL-1β requires the activation of MAP kinase pathways as a consequence of an IL-1β receptor stimulation. Moreover, we have observed that IL-1β regulates the expression of Cp and Fpn genes through (i) p38 MAPK-mediated activation of C/EBP transcription factor, (ii) ERK1/2-, JNK1- and partially p38 MAPK-dependent activation of AP-1, and through (iii) activation of NF-κB partially mediated by p38 MAPK.

Glutathione synthesis inhibitor butathione sulfoximine regulates ceruloplasmin by dual but opposite mechanism: Implication in hepatic iron overload

Glutathione (GSH) depletion is often detected in chronic pathological conditions like hepatitis C infection, alcohol consumption or xenobiotic assault with simultaneous reactive oxygen species (ROS) generation and hepatic iron overload. However, relation between GSH depletion and regulators of iron homeostasis is not clear so far. To determine that hepatic HepG2 cells were treated with GSH synthesis inhibitor butathione sulfoximine (BSO) and a dual regulation of ceruloplasmin (Cp) that involves in hepatic iron release was detected unlike other iron homeostasis regulators. BSO treatment that caused marginal GSH deficiency increased Cp synthesis due to increased transcription mediated by activator protein (AP)-1-binding site. In higher GSH deficiency (> 40 %) with increased ROS generation, Cp expression was decreased due to promotion of Cp mRNA decay mediated by 3'untranslated region (3'UTR) as found by transfecting chimera of chloramphenicol acetyl transferase (CAT) gene with Cp 3'UTR. RNA gel shift assay showed significant reduction in 3'UTR binding protein complex in similar condition. Decreased CAT expression and RNA-protein complex binding are reversed by pretreatment with antioxidant N-acetyl cysteine suggesting 3'UTR binding protein complex is redox-sensitive. This unique and opposite regulation of Cp provides a mechanism of hepatic iron-deposition during glutathione deficiency detected in chronic pathological conditions.

Diphosphine- and CO-Induced Fragmentation of Chloride-bridged Dinuclear Complex and Cp*Ir(μ-Cl)3Re(CO)3 and Attempted Synthesis of Cp*Ir(μ-Cl)3Mn(CO)3: Spectroscopic Data and X-ray Diffraction Structures of the Pentamethylcyclopentadienyl Compounds [Cp*IrCl{(Z)-Ph2PCH = CHPPh2}][Cl]·2CHCl3 and Cp*Ir(CO)Cl2

The confacial bioctahedral compound Cp*Ir(μ-Cl)3Re(CO)3 (1) undergoes rapid fragmentation in the presence of the unsaturated diphosphine ligand (Z)-Ph2PCH = CHPPh2 to give the mononuclear compounds [Cp*IrCl{(Z)-Ph2PCH = CHPPh2}][Cl] (2) and fac-ClRe(CO)3[(Z)-Ph2PCH = CHPPh2] (3). 2 has been characterized by 1H and 31P NMR spectroscopy and X-ray diffraction analysis. 2·2CHCl3 crystallizes in the monoclinic space group C2/c, a = 35.023 (8) A, b = 10.189 (2) A, c = 24.003 (6) A, β = 103.340 (3), V = 8,335 (3) A3, Z = 8, and d calc = 1.647 Mg/m3; R = 0.0383, R w = 0.1135 for 8,178 reflections with I > 2σ(I). The Ir(III) center in 2 exhibits a six-coordinate geometry and displays a chelating diphosphine group. Compound 1 reacts with added CO with fragmentation to yield the known compounds Cp*Ir(CO)Cl2 (4) and ClRe(CO)5 (5) in near quantitative yield by IR spectroscopy. Using the protocol established by our groups for the synthesis of 1, we have explored the reaction of [Cp*IrCl2]2 with ClMn(CO)5 as a potential route to Cp*Ir(μ-Cl)3Mn(CO)3; unfortunately, 4 was the only product isolated from this reaction. The solid-state structure of 4 was determined by X-ray diffraction analysis. 4 crystallizes in the triclinic space group P−1, a = 7.4059 (4) A, b = 7.8940 (4) A, c = 11.8488 (7) A, α = 80.020 (1), β = 79.758 (1), γ = 68.631 (1), V = 630.34 (6) A3, Z = 2, and d calc = 2.246 Mg/m3; R = 0.0126, R w = 0.0329 for 2,754 reflections with I > 2σ(I). The expected three-legged piano-stool geometry in 4 has been crystallographically confirmed. The reactivity of the chloride-bridged dimer Cp*Ir(μ-Cl)3Re(CO)3 (1) with the unsaturated diphosphine ligand (Z)-Ph2PCH = CHPPh2 has been examined. Rapid fragmentation of 1 occurs in the presence of excess diphosphine to afford the ionic Ir(III) species [Cp*IrCl{(Z)-Ph2PCH = CHPPh2}][Cl] (2) and fac-ClRe(CO)3[(Z)-Ph2PCH = CHPPh2] (3). 1 reacts rapidly with CO to furnish Cp*Ir(CO)Cl2 (4) and ClRe(CO)5 (5). The attempted synthesis of Cp*Ir(μ-Cl)3Mn(CO)3 from [Cp*IrCl2]2 and ClMn(CO)5 was unsuccessful and afforded compound 4 as the sole isolable product. The solid-state structures of 2·2CHCl3 and 4 have been established by X-ray crystallography.

Synthesis, Structure, and Selective Cytotoxicity of Organometallic Cp*RuII O-Alkyl-N-phenylcarbamate Sandwich Complexes

Tetraphenylborate salts of the η6-arene Cp*RuII O-alkyl-N-phenyl carbamate organometallic sandwich complexes, [Cp*Ru(PhNHCO2R)]BPh4 for R = Me (1), Et (2), and n-Pr (3), have been prepared by a facile one-pot reaction between ruthenium trichloride, pentamethylcyclopentadiene, and phenylisocyanate in refluxing alcohol solutions, and have been characterized by Fourier-transform IR and NMR spectroscopy, electrospray mass spectrometry, and single-crystal X-ray structure determinations. In vitro cytotoxicity studies show the complexes to be potent growth inhibitors for a range of tumour cell lines, while expressing significantly lower levels of toxicity towards a normal human fibroblast cell line.

Tetramethylaluminate and Tetramethylgallate Coordination in Rare-Earth Metal Half-Sandwich and Metallocene Complexes

The synthesis of half-sandwich tetramethylaluminate complexes Cp*Y(AlMe4)2 (Cp* = C5Me5) was achieved by applying two synthesis protocols: (a) protonolysis of Y(AlMe4)3 with excess HCp* at ambient temperature; (b) alkylamide elimination using Cp*Y(NiPr2)2(THF) and trimethylaluminum at ambient temperature. The tetramethylgallate derivative Cp*Y(GaMe4)2 was obtained from the equimolar reaction of Y(GaMe4)3 with HCp* or by addition of 2 equiv of trimethylgallium to [Cp*YMe2]3. The half-sandwich complexes Cp*Y(MMe4)2 (M = Al, Ga) display similar structural chemistry featuring highly fluxional methyl groups in solution and one planar and one atypically bent Y(μ-Me)2M moiety in the solid state. Complexes [Cp*2Ln(MMe4)] (Ln = Y, La; M = Al, Ga) were synthesized from Ln(MMe4)3 with excess HCp* at elevated temperature. Such metallocene complexes show the known monomer−dimer equilibria in solution, with the entropically disfavored dimer prevailing at low temperature. Dimeric [Cp*2La(AlMe4)]2 and [Cp*2Y(GaMe4)]2 as ...

Synthesis and Characterization of Cp4Fe4(CO)4-Functionalized Terpyridine Molecule and Its Iron(II) and Ruthenium(II) Complexes

Reaction of Cp3Fe4(CO)4(C5H4CHO) (1) and 2-acetylpyridine produces Cp3Fe4(CO)4(C5H4CH═CHC(═O)(2-C5H4N)) (2) and Cp3Fe4(CO)4(C5H4CH(CH2C(═O)(2-C5H4N))2) (3), which can convert to Cp3Fe4(CO)4(4′-C5H4-2,2′:6′,2′′-terpyridine) (4) in moderate yields. Coordination of 4 to Fe(II) and Ru(II) ions afford the double-cluster complexes [(Cp3Fe4(CO)4(4′-C5H4-2,2′:6′,2′′-terpyridine))2Ru](PF6)2 (5) and [(Cp3Fe4(CO)4(4′-C5H4-2,2′:6′,2′′-terpyridine))2Fe](PF6)2 (6), respectively. Compounds 4−6 have been characterized by mass, NMR, and UV−vis spectroscopy, and the structure of 4 was determined by an X-ray diffraction study.