Cr Equivalents Research Articles

Quantifying and normalizing the combined phytotoxicity of mixed-valence chromium in soil integrated by toxicity equivalence

When Cr(VI) and Cr(III) coexist, the reasonable assessment of the combined toxicity of chromium in soil and its ecological risk is still not well resolved. In the present study, exogenous mixed concentration combinations were set up to determine the interaction and combined toxicity of Cr(VI) and Cr(III), which were quantified as measured total and resin extractable forms for dose-response experiments with barley root elongation. The concept of toxicity equivalence "α" (the ratio of toxicity intensity coefficient between Cr(VI) and Cr(III), which can be expressed as the relative toxic strength of Cr(VI) to Cr(III)) was proposed for the toxicity assessment of mixed-valence chromium in soil. The results showed that the dose-response relationship was determined more precisely by the extended independent action model (e-IA) than traditional models (e.g., concentration addition model), and the mutual antagonism for resin extractable form (Resin-Cr) was stronger than the measured total form (T-Cr). The values of toxicity equivalence (α) between coexisting Cr(VI) and Cr(III) as Resin-Cr and T-Cr were 0.74 and 160, respectively, which indicated Resin-Cr(III) had relatively stronger toxicity than Resin-Cr(VI), while T-Cr(III) was much less than T-Cr(VI). The α values between Cr(VI) and Cr(III) decreased with their more active forms (decreased to about 0.5% of the original), even as total concentration and activity in solutions, making a dialectical view of the toxicity of both in different forms necessary. Finally, the log-logistic models were developed, enabling mixed-valence Cr toxicity to be assessed from a unilateral perspective using the Cr(III) equivalence concentration (Cr(III)-eq). This work provided innovative ideas for ecological threshold studies for mixed-valence metals in soils.

Binding Chromium(III) to Form Mixed Cr(III),Fe(III) Serum Transferrins.

Transferrin, Tf, the protein that transports iron as Fe(III) from the blood to the tissues via endocytosis, is believed to also transport Cr(III). Under physiological conditions, Tf binds and releases Cr(III) rapidly from Cr(III)2-Tf; however, the major form of Tf in the bloodstream is mono-ferric Tf (Fe(III)-Tf). Given the low concentration of Cr(III) in the bloodstream, the form of Cr(III)-containing Tf that is transported is probably monochromic, monoferric-Tf (Cr(III),Fe(III)-Tf). Given that Tf has two specific metal-binding sites, one in both its C-terminal and its N-terminal lobe, two forms of Cr(III),Fe(III)-Tf can form. The binding of Cr(III) to mono-ferric Tf to generate both forms of Cr(III),Fe(III)-Tf has been examined in detail for the first time. The addition of Cr(III) to monoferric Tfs in 100mM HEPES and 25mM bicarbonate solution, pH 7.4, resulted in a rapid binding of Cr(III) to the open metal-binding site of the Tfs. Titrations of the monoferric Tfs with Cr(III) indicate the tight binding on one Cr(III) in each case. The binding of Cr(III) to monoferric Tfs is accompanied by conformational changes similar to adding two equivalents of Cr(III) to apoTf. Thus, mono-ferric Tfs bind one equivalent of Cr(III) rapidly and tightly to form mixed Cr(III),Fe(III)-Tfs. Cr(III) is probably transported as mixed Cr(III),Fe(III)-Tfs.

Domain knowledge-guided interpretive machine learning: formula discovery for the oxidation behavior of ferritic-martensitic steels in supercritical water

A general formula with high generalization and accurate prediction power is highly desirable for science, technology and engineering. In addition to human beings, artificial intelligence algorithms show great promise for the discovery of formulas. In this study, we propose a domain knowledge-guided interpretive machine learning strategy and demonstrate it by studying the oxidation behavior of ferritic-martensitic steels in supercritical water. The oxidation Cr equivalent is, for the first time, proposed in the present work to represent all contributions of alloying elements to oxidation, derived by our domain knowledge and interpretive machine learning algorithms. An open-source tree classifier for linear regression algorithm is also, for the first time, developed to materialize the formula with collected data. This algorithm effectively captures the linear correlation between compositions, testing environments and oxidation behaviors from the data. The sure independence screening and sparsifying operator algorithm finally assembles the information derived from the tree classifier for linear regression algorithm, resulting in a general formula. The general formula with the determined parameters has the power to predict, quantitatively and accurately, the oxidation behavior of ferritic-martensitic steels with multiple alloying elements exposed to various supercritical water environments, thereby providing guidance for the design of anti-oxidation steels and hence promoting the development of power plants with improved safety. The present work demonstrates the power of domain knowledge-guided interpretive machine learning with respect to the data-driven discovery of physics-informed formulas and the acceleration of materials informatics development.

Ethylene polymerization by binuclear chromium complex with tetrakis(pyrazolyl-methyl)benzene ligand

The reaction of one equivalent of 1,2,4,5-tetrakis(pyrazolyl-methyl)benzene ligand (L) with two equivalents of Cr(THF)3Cl3 in tetrahydrofuran has produced a binuclear neutral complex of general formula [Cr2L(THF)2Cl6] (1). It was characterized by mass spectrometry, Fourier-transformed infrared, X-ray photoelectron spectroscopy, and magnetic susceptibility. Theoretical calculations supported the formation of binuclear complex (1) with each hexacoordinate metal center. This complex was active in ethylene polymerization employing methylaluminoxane as cocatalyst, with moderate activities (5.7–20.8 kg polymer/(mol precat.) (bar) (h)). The reaction parameters such as temperature, monomer pressure, and Al/Cr ratio were studied. An increase of reaction temperature produced a decreasing of catalytic activity. However, an increase in the monomer pressure did not produce a significant increase in catalytic activity. The Al/Cr ratios used to activate this complex are smaller than those reported for the tris(pyrazolyl)borate chromium complex. This system produced high-density polyethylenes with wide molecular weight, Mw, distributions between 42,280 and 74,346 and polydispersity index from 2.3 to 6.6.

Binding of Cr2-transferrin to Transferrin Receptor Enhances the Rate of Chromium Loss and Is Dependent on the Conformation of Transferrin (P24-053-19)

ObjectivesTransferrin, Tf, the protein transports iron from the blood to the tissues via endocytosis, is believed to also transport chromium(III), Cr(III). Recently, the release of Cr(III) from Tf has been postulated to be too slow for appreciable quantities of Cr(III) to be released during the lifetime of an endosome. The objective of this work was to measure the rate of Cr(III) release from human serum Tf as a function of Tf confirmation and as the transferrin-transferrin receptor (TfR) complex. MethodsCr(III) was added to apoTf in a buffered solution at pH 7.4 containing 25 mM bicarbonate at 37 °C. After time intervals, ultraviolet spectra were collected, or aliquots were removed and frozen for analysis by electron paramagnetic resonance (EPR) spectroscopy, which can distinguish free Cr(III) and Cr(III) bound to the two metal binding sites of Tf. To model the acidification of the endosome that triggers release of metal ions from Tf, the Cr(III)2-Tf solutions were acidified by the addition of hydrochloric acid to pH 4.5 or 5.5. At time intervals after acidification, samples were again analyzed by ultraviolet and EPR spectroscopies. Similar studies were performed in the presence of Tf receptor, which binds two equivalents of Cr(III)2-Tf. ResultsThe loss of Cr(III) from the two metal-binding sites of Tf occur at different rates. Different confirmations of the Cr2-Tf complex exist depending on the conditions of Cr2-Tf formation. The conformation that forms rapidly under physiological conditions loses Cr(III) faster than conformations that form over longer periods of time. Binding of Cr(III)2-Tf to TfR facilitates the release of Cr. ConclusionsThe conformation of Cr(III)2-transferrin that forms under physiological conditions when complexed with transferrin receptor can release Cr at physiologically significant rates consistent with transferrin serving as the major Cr(III) transport agent between the blood stream and tissues. Funding SourcesThe University of Alabama College of Arts and Sciences Research Award.

Mechanical properties of 304 austenite stainless steel manufactured by laser metal deposition

Laser metal deposition (LMD) is a common manufacturing technique of laser additive manufacturing (LAM) which belongs to coaxial powder feeding method. The LMDed SS304 specimens are fabricated by the same combination of the process parameters so that they have the similar properties. The microstructure is similar to that of the selective laser melted (SLMed) specimen. The grain sizes of the LMDed specimen are compared with those of the specimens manufactured by the traditional method and SLM. Through the calculation of Ni and Cr equivalents in the LMDed SS304 specimen and the analytical results of electron backscattered diffraction (EBSD) and energy dispersive spectroscope (EDS), the phase compositions of the LMDed SS304 specimen are evaluated. The hardness of the LMDed specimen is compared with that of the conventionally manufactured wrought SS304 and SLMed specimens. And due to the differences of the grain size and phase composition on the different directions, the hardness of the LMDed specimen is anisotropic. The static tensile properties (ultimate tensile strength (UTS), yield strength (σ0.2) and elongation (EL)) and fatigue strength (FS) of the LMDed specimen are compared with those of the specimens made by the traditional method and SLM. The SN curve is established by the multiple experiments. Scanning electron microscopy (SEM) is applied to observe the fracture morphology of the static tension and tension-compression fatigue tests. And EDS is applied to analyze the chemical compositions of the particles on the fracture surface. As expected, LMD has the higher static tensile properties and fatigue strength than those of the specimen manufactured by the traditional method.

The effects of the glycation of transferrin on chromium binding and the transport and distribution of chromium in vivo

Chromium (III) has been shown to act as a pharmacological agent improving insulin sensitivity in rodent models of obesity, insulin resistance, and diabetes. To act in beneficial fashion, chromium must reach insulin-sensitive tissues. Chromium is transported from the bloodstream to the tissues by the iron-transport protein transferrin. When blood concentrations of glucose are high (as in a diabetic subject), transferrin can be glycated, modifying its ability to bind and transport iron. However, the effects of glycation of transferrin on its ability to bind and transport Cr have not been examined previously. Storage of transferrin at 37°C in the presence and absence of glucose has significant effects on the binding of Cr. Transferrin stored in the absence of glucose only binds one equivalent of Cr tightly, compared to the normal binding of two equivalents of Cr by transferrin. Glycated transferrin (stored in the presence of glucose) binds two equivalents of Cr but the changes in its extinction coefficient at 245nm that accompany binding suggest that the Cr-bound transferrin possesses a conformation that deviates appreciably from untreated transferrin. These changes have dramatic effects, greatly reducing the ability of transferrin to transport Cr in vivo in rats. The results suggest that glycation of transferrin in subjects with high blood glucose concentrations should reduce the ability of Cr from pharmacological agents to enter tissues.

Bifunctional Brønsted–Lewis solid acid as a recyclable catalyst for conversion of glucose to 5-hydroxymethylfurfural and its hydrophobicity effect

A novel polydivinylbenzene polymeric material containing water-tolerant SO2NHSO2C4F9 with 2 equivalents of Cr(iii) was explored as a catalyst of the one-pot conversion of glucose to 5-hydroxymethylfurfural (HMF) in a biphasic system.

The Effects of Si and Al Alloying on α/γ Phase Equilibria in Fe-Cr-Ni-Mn Based Ternary and Quaternary Systems

Phase equilibria between the ferrite phase (α) and the austenite phase (γ) were investigated in the iron-rich corner of the Fe-Cr-Mn-Ni-Si/Al systems at 1000 °C using a diffusion multiple approach and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) techniques. Cr equivalents of Si and Al are established as a function of Ni and Mn content in contrast to fixed values reported in other studies. The Cr equivalents of Si (CreqSi) are in the range between −0.5 and 1.3 being positive at 0 wt.% Mn and with values slightly below zero at 5-15 wt.% Mn. The Cr equivalents of Al (CreqAl) ranged between 0.6 and 4.8 decreasing with increase in Ni and Mn content. When compared to CreqAl, the CreqSi do not show a strong dependence on Ni and Mn content. Thermodynamic calculation using Thermo-Calc software agrees with the experimental results qualitatively.

Fluorescent sensors based on BODIPY derivatives for aluminium ion recognition: an experimental and theoretical study

Two BODIPY derivative sensors for metal ion recognition containing 10-(4-hydroxyphenyl) (L1) and 10-(3,4-dihydroxyphenyl) (L2) were synthesized in a one-pot reaction of benzaldehyde derivative and 2,4-dimethylpyrrole in the presence of trifluoroacetic acid as catalyst. The binding abilities between these sensors and 50 equivalents of Na(+), K(+), Ag(+), Ca(2+), Fe(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Pb(2+), Al(3+) and Cr(3+) ions were studied using UV-vis and fluorescent spectroscopic methods. Of all the metal ions tested, Al(3+) ion showed the greatest decrease in intensity in the spectra of the sensors, and therefore Al(3+) ion forms the strongest complex. The binding abilities of BODIPY receptors with Na(+), Ag(+), Ca(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+) and Al(3+) ions were also investigated using density functional theory (DFT) calculations at B3LYP/LanL2DZ theoretical level. The calculated results point to the same conclusion. DFT calculations also provided the HOMO-LUMO energy levels, which can explain the spectrum change upon complexation.

Sequence of the peptide component of low‐molecular‐weight chromium‐binding substance

Two biomolecules are known to bind chromium in the body: transferrin and low‐molecular‐weight chromium‐binding substance (LMWCr). While transferrin is responsible for the transfer of Cr from the bloodstream to the tissues, LMWCr has been proposed to have a function in the removal of chromium from the body and in the enhancement of insulin signaling. LMWCr is comprised of a peptide that can tightly bind four equivalents of Cr(III). While reports on the magnetic and spectroscopic properties of the chromic centers have appeared, research has been hampered by difficulties in characterizing the organic portion of the biomolecule. Treatment of LMWCr with trifluoroacetic acid releases the Cr, converts the amino terminal glutamate of the peptide to pyroglutamate, and generates a heptapeptide. This procedure has allowed the isolation of the chromium‐free peptide component of LMWCr from a variety of sources; this peptide can be sequenced by mass spectrometry.

Effect of elemental interaction on microstructure of CuCrFeNiMn high entropy alloy system

CuCrFeNiMn alloy system with different elemental contents is synthesized by using the arc melting and casting method. Effect of elemental interaction on microstructure of these alloys is investigated by means of Ni equivalent and Cr equivalent. The alloys exhibit quite simple solid solution phases with FCC or FCC + BCC mixed structures. Bimodal distribution and peak shift in XRD patterns resulted from the lattice constants difference of FCC phase are observed in most alloys. The formation of simple solid solution phase is associated with the slight difference in atomic size and properly mixing enthalpy. The Cu, Mn, Cr and Fe are mostly segregated in dendrite or interdendrite regions, while the Ni is homogeneously distributed in the alloys. In addition, alloys with higher Ni equivalent principally consist of single FCC phase; while those with higher Cr equivalent are mainly composed of FCC + BCC mixed structures.

Fonctions et feuilletages Levi-flat. Étude locale

We define the notion of CR equivalence for Levi-flat foliations and compare in a local setting these foliations to their linear parts. We study also the situation where the foliation has a first integral; a condition is given so that this integral is the real part of a holomorphic function.

2,2′-Bipyrimidine transition metal complexes: Synthesis, reaction chemistry and solid state structures

2,2′-Bipyrimidine metal complexes with Ti, Mo, Fe, Ru, Pt, Ag, and Cu transition metal atoms have been synthesized and structurally characterized. These molecules were prepared by following synthesis methodologies. The reaction of 2,2′-bipyrimidine ( 1; bipym) with {[Ti](μ-σ,π-C CSiMe 3) 2}AgOTf ([Ti] = (η 5-C 5H 4SiMe 3) 2Ti, OTf = OSO 2CF 3) ( 2) in a 1:1 molar ratio gave [{[Ti](μ-σ,π-C CSiMe 3) 2}Ag(bipym)]OTf ( 3) which on further treatment with another equivalent of 2 produced [({[Ti](μ-σ,π-C CSiMe 3) 2}Ag) 2(μ-1,2,3,4-bipym)](OTf) 2 ( 4). As consequence thereof, the coordination number of Ag(I) was changed from 3 to 4. A platinum–bipym complex with two acetylide substituents was accessible by the gradual reaction of 1 with K 2[PtCl 4] ( 5) and two equivalents of HC CR ( 7a, R = SiMe 3; 7b, R = Fc; 7c, R = Rc; Fc = (η 5-C 5H 4)(η 5-C 5H 5)Fe; Rc = (η 5-C 5H 4)(η 5-C 5H 5)Ru) in di- iso-propylamine and in presence of [CuI]. Originating from cis-[(bipym)Pt(C CR) 2] ( 8a, R = SiMe 3; 8b, R = Fc; 8c, R = Rc) diverse multinuclear complexes with two, three or four different transition metals could be obtained. These are: [((CO) 4Mo)(μ-1,2,3,4-bipym)Pt(C CFc) 2] ( 10), [(AgClO 4)(μ-1,2,3,4-bipym){[Pt(μ-σ,π-C CFc) 2]AgOClO 3}] ( 12), [(McC C) 2Pt(μ-1,2,3,4-bipym)({[Ti](μ-σ,π-C CSiMe 3) 2}M)]X ( 15a, Mc = Fc, M = Cu, X = PF 6; 15b, Mc = Rc, M = Cu, X = PF 6; 15c, Mc = Fc, M = Ag, X = ClO 4), and [(McC C) 2Pt(μ-1,2,3,4-bipym)PtCl 2] ( 17). Like other organometallic Pt–Ag tweezer complexes, compound 12 decomposed to give FcC C–C CFc ( 13). During prolonged stirring of 15a and 15b, respectively, [(McC C) 2Pt(μ-1,2,3,4-bipym)({[Ti](μ-σ,π-C CSiMe 3)(μ-σ,π-C CH)}M)]X ( 15′a, M = Cu, X = PF 6; 15′b, M = Cu, X = PF 6) was formed. The structures of 8b, 8c, 15a′, and 15b′ in the solid state are reported. All complexes exhibit the anticipated planar dinuclear Pt–M structure (M = Pt, Cu, Ag) with the 2,2′-bipyrimidine unit in a μ-1,2,3,4-bridging mode. Electrochemical investigations were carried out with 8a, 8b, and 8c and show that no significant influence of R on the bipym redox potentials exists. The typical redox behavior for the bipym, ferrocene, ruthenocene units and platinum were observed.

Low-Temperature Aging Characteristics of Type 316L Stainless Steel Welds: Dependence on Solidification Mode

Thermal aging embrittlement of light water reactor (LWR) components made of stainless steel cast has been recognized as a potential degradation issue, and careful attention has been paid to it. Although welds of austenitic stainless steels have γ-δ duplex microstructure, which is similar to that of the stainless steel cast, examination of the thermal aging characteristics of the stainless steel welds is very limited. In this investigation, two types of type 316L stainless steel weld metal with different solidification modes were prepared using two kinds of filler metals having tailored Ni equivalent and Cr equivalent. Differences between the two weld metals in the morphology of microstructure, in the composition of δ-ferrite, and in hardening behaviors with isothermal aging at 335 °C have been investigated. The hardness of the ferrite phase has increased with aging time, while the hardness of austenite phase has stayed the same. The mottled aspect has been observed in δ-ferrite of aged samples by transmission electron microscopy (TEM) observation. These characteristics suggest that spinodal decomposition has occurred in δ-ferrite by aging at 335 °C. The age-hardening rate of δ-ferrite was faster for the primary austenite solidification mode (AF mode) sample than the primary ferrite solidification mode (FA mode) sample in the initial stage of the aging up to 2000 hours. It has been suggested that the solidification mode can affect the kinetics of spinodal decomposition.

Catalytic asymmetric Nozaki–Hiyama reactions with a tridentate bis(oxazolinyl)carbazole ligand

Nozaki-Hiyama reactions are powerful Cr(II)-mediated C--C bond-forming reactions conducted under mild conditions that show excellent compatibility with various functional groups. Therefore, Nozaki-Hiyama reactions have been utilized for many total syntheses of complex natural products, but at least two equivalents of Cr(II) salt are required to complete the reaction because Cr(II) salt is a one-electron donor. In 1996, however, the quantity of Cr(II) salts required was successfully reduced by a catalytic redox system reported by Fürstner and Shi. Since the report by Fürstner, the catalytic asymmetric Nozaki-Hiyama reactions have attracted attention because they would allow control over enantioselectivity, thereby further enhancing the versatility of Nozaki-Hiyama reactions. In this review, we describe the development of a tridentate bis(oxazolinyl)carbazole ligand for the catalytic asymmetric Nozaki-Hiyama allylation, methallylation, propargylation, and allenylation. Also described are their successful applications to the highly stereoselective construction of the side chain of calcitriol lactone, as well as structure elucidation and the enantioselective first total synthesis of the potent 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, FR901512 and FR901516.

Formation of Ferrite with Cr Equivalents and Solidification Rates in Mod. (9-12)Cr-1Mo Steels

The influence of solidification rates and Cr equivalents on the formation of the ferrite was studied by directional solidification in mod. (9-12)Cr-1Mo steels. It was found that the volume fraction of ferrite increased as increasing Cr equivalent and solidification rate. The volume fraction of the ferrite showed much higher at low solidification rates with the planar or cellular interface than that at high solidification rates with the dendritic interface. The volume fraction of ferrite in solidification microstructure showed much higher than that in extruded and heat-treated alloys. It depends on not only solidification rate and Cr equivalent but also the solidification fraction. At low solidification rates, there occurs segregation because the solid/liquid interface was planar or cellular, and it makes composition change with solidification fractions. The formation of ferrite has been discussed with Cr equivalent and solidification rate.

Bayesian neural network analysis of ferrite number in stainless steel welds

Bayesian neural network (BNN) analysis has been used in the present work to develop an accurate model for predicting the ferrite content in stainless steel welds. The analysis reveals the influence of compositional variations on ferrite content for the stainless steel weld metals, and examines the significance of individual elements, in terms of their influence on ferrite content in stainless steel welds, based on the optimised neural network model. This neural network model for ferrite prediction in stainless steel welds has been developed using the database used to generate the WRC-1992 diagram and the first author's laboratory data. The optimised committee model predicts the ferrite number (FN) in stainless steel welds with greater accuracy than the constitution diagrams and the other FN prediction methods. Using this BNN model, the influence of variations of the individual elements on the FN in austenitic stainless steel welds is also determined, and it is found that the change in FN is a non-linear function of the variation in the concentration of the elements. Elements such as Cr, Ni, N, Mo, Si, Ti, and V are found to influence the FN more significantly than the other elements present in stainless steel welds. Manganese is found to have a weaker influence on the FN. A noteworthy observation is that Ti influences the FN more significantly than does Nb, whereas the WRC-1992 diagram considers only the Nb content in calculating the Cr equivalent.

Compact homogeneous CR manifolds

We classify all compact simply connected homogeneous CR manifolds M of codimension one and with non-degenerate Levi form up to CR equivalence. The classification is based on our previous results and on a description of the maximal connected compact group G(M) of automorphisms of M. We characterize also the standard homogeneous CR manifolds as the homogeneous CR manifolds whose group G(M) in not semisimple.

Die Beständigkeit von (η 5-C 5H 4R) 2Ti(CCR′) 2 in Abhängigkeit von den elektronischen Eigenschaften der Cyclopentadienyl-Liganden. Die Festkörperstruktur von (η 5-C 5H 5)(η 5-C 5H 4SiMe 3)Ti(CCSiMe 3) 2

The synthesis of the titanocene dichlorides (η 5-C 5H 5)(η 5-C 5H 4SiMe 3)TiCl 2 ( 3) and (η 5-C 5H 4CO 2R) 2TiCl 2 ( 8a, R=CH 3; 8b, R=CH 2CH 3), which contain either electron-donating or electron-withdrawing substituents at the cyclopentadienyl fragments is discussed. While the reaction of 8a or 8b with LiCCR′ in different stoichiometric ratios leads only to product mixtures from which no pure components could be isolated, treatment of 3 with two equivalents of LiCCR′ ( 9a, R′=C 6H 5; 9b, R′= t Bu; 9c, R′=SiMe 3) selectively produces the bis(alkinyl) titanocenes (η 5-C 5H 5)(η 5-C 5H 4SiMe 3)Ti(CCR′) 2 ( 10a, R′=C 6H 5; 10b, R′= t Bu; 10c, R′=SiMe 3). However, it was found that when complex 10c is stirred in tetrahydrofuran solutions, Me 3SiCC is eliminated and Me 3SiCCCCSiMe 3 ( 11) along with [(η 5-C 5H 5)(η 5-C 5H 4SiMe 3)Ti(CCSiMe 3)] 2 ( 12) is formed.The solid-state structure of (η 5-C 5H 5)(η 5-C 5H 4SiMe 3)Ti(CCSiMe 3) 2 ( 10c) is reported. Complex 10c crystallises in the monoclinic space group P c with two independent molecules in the asymmetric unit and with the cell constants a=20.8131(6), b=10.6615(3), c=12.2543(4) Å, β=101.12(3)°, V=2668.14(14) Å 3 and Z=4. 10c exhibits a pseudotetrahedrally coordination sphere around the Ti(IV) centre comprised of the two σ-bonded alkynyl ligands Me 3SiCC and the η 5-coordinated cyclopentadienyl moieties C 5H 5 as well as C 5H 4SiMe 3.