Metallic lanthanides chemical reactivity

We have found that the late metal congeners of this important compound class are easily synthesized and can be derivatized to yield aryl monocyclo-octatetraene lanthanide complexes if the metal is small (Er—Lu) and the ligand bulky and chelating. The synthesis of these compounds clears the way for comparative reactivity studies (with cyclopentadienyl lanthanide complexes) and allows investigations of fundamental chemical reactivity to be conducted for this ligand system. 

The present focussing of interest to this type of spectroscopy for lanthanide materials has undoubtedly led to some duplication of work. As an example we mentirm the numerous studies of the ytterbium metal. At least ten published papers have reported the photoelectron valence band spectrum of this element. However, in an early stage of development of a research technique, such as the present photoelectron spectroscopy in connection with highly chemically reactive materials, such duplication might be quite useful. 

The basis for the claim of discovery of an element has varied over the centuries. The method of discovery of the chemical elements in the late eightenth and the early nineteenth centuries used the properties of the new sustances, their separability, the colors of their compounds, the shapes of their crystals and their reactivity to determine the existence of new elements. In those early days, atomic weight values were not available, and there was no spectral analysis that would later be supplied by arc, spark, absorption, phosphorescent or x-ray spectra. Also in those days, there were many claims, e.g., the discovery of certain rare earth elements of the lanthanide series, which involved the discovery of a mineral ore, from which an element was later extracted. The honor of discovery has often been accorded not to the person who first isolated the element but to the person who discovered the original mineral itself, even when the ore was impure and that ore actually contained many elements. The reason for this is that in the case of these rare earth elements, the earth now refers to oxides of a metal not to the metal itself This fact was not realized at the time of their discovery, until the English chemist Humphry Davy showed that earths were compounds of oxygen and metals in 1808. 

After the discovery of plutoninm and before elements 95 and 96 were discovered, their existence and properties were predicted. Additionally, chemical and physical properties were predicted to be homologous (similar) to europium (gjEu) and gadolinium ( Gd), located in the rare-earth lanthanide series just above americium (gjAm) and curium ((,jCm) on the periodic table. Once discovered, it was determined that curium is a silvery-white, heavy metal that is chemically more reactive than americium with properties similar to uranium and plutonium. Its melting point is 1,345°C, its boihng point is 1,300°C, and its density is 13.51g/cm. ... 

Berkelium is a metallic element located in group 11 (IB) of the transuranic subseries of the actinide series. Berkelium is located just below the rare-earth metal terbium in the lanthanide series of the periodic table. Therefore, it has many chemical and physical properties similar to terbium ( Tb). Its isotopes are very reactive and are not found in nature. Only small amounts have been artificially produced in particle accelerators and by alpha and beta decay. 

In addition to making the third-series transition metals smaller, the lanthanide contraction also makes them less reactive because the valence electrons are relatively close to the nucleus and less susceptible to chemical reactions. This accounts for the relative inertness—or nobility—of these metals, particularly gold and platinum. Moreover, the third-series transition metals are the densest known elements, having about the same atomic size as the second-series transition metals but twice the atomic weight. The densest element is iridium (Ir, Z = 77) at 22.65 g/cm. ... 

The 4f orbitals in general are much less reactive than the 5d orbitals (transition metals). The f orbitals do not span out as far into physical space as the d orbitals, so they are harder to reach and harder to do chemical reactions with. Additionally, the 4d and 5d elements are relatively inert in comparison to the 3d elements. Therefore, not only are the lanthanides less reactive because of the employment of 4f orbitals, but any d orbitals that they might employ are going to be less reactive than the d orbitals of the earlier d block elements. 

Trimethylphosphine is a ligand of proven utility in oiganometallic chemistry. However, because of its expense when purchased from commercial sources (Strero Chemicals) or its poor to moderate yidds when isolated as the silver iodide adduct [AgI(PMe3)l4, its potential is not fully realized. Frequently, large quantities of the phosphine are required, for example, as a reactive solvent or in the field of lanthanide and actinide chemistry, wherein the lability of the phosphine ligand may require crystallization from neat tri-methylphosphine. Similar considerations apply in exploratory synthetic early transition metal chemistry. In transition metal ylide chemistry, access to quantities of PMea is also very desirable, particularly when excess ylide is required. The volatility of PMe3 facilitates work-up of reaction mixtures and... 

Postcolumn derivatization with absorbance spectroscopy Postcolumn derivatization reactions involve the chemical reaction of the analyte with a chromophore, after the analyte has passed through the column, followed by the detection of the analyte by UV-Vis absorbance spectroscopy. This type of detection system is typically used for transition and lanthanide metal cations due to the incompatibilities between the transition metal complexing eluent and the conductivity supressor. The properties of the postcolumn derivatization species should include high molar absorptivity of complexes, reactivity with most metals, formation of stable metal com-... 

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