Lutetium oxidation states

Reference has been made already to the existence of a set of inner transition elements, following lanthanum, in which the quantum level being filled is neither the outer quantum level nor the penultimate level, but the next inner. These elements, together with yttrium (a transition metal), were called the rare earths , since they occurred in uncommon mixtures of what were believed to be earths or oxides. With the recognition of their special structure, the elements from lanthanum to lutetium were re-named the lanthanons or lanthanides. They resemble one another very closely, so much so that their separation presented a major problem, since all their compounds are very much alike. They exhibit oxidation state -i-3 and show in this state predominantly ionic characteristics—the ions. 

The mechanism for polymerization of propylene with heterogeneous catalysts is very similar to that of ethylene. Studies with a homogeneous catalyst of a lanthanide element provided early mechanistic evidence. The complex used in these studies was 6.15. In 6.15 lutetium is in a 3+ oxidation state and has the electronic configuration of 4fu. In other words Lu3+ has a full/shell and 6.15 is a diamagnetic complex. 

Somewhat similar reactions with ii -CsMe5)2ThR2 have also been investigated.It is likely that neither of these two reactions proceeds by oxidative addition becau.se lutetium and thorium are in high oxidation states in the reactants. 

As shown in Table I, lanthanum and lutetium oxides have Sq ground states and consequently their heat capacities should be attributed to lattice vibration. Data on these substances may be used to represent the lattice contribution to a first approximation for neighboring isostructural (and nearly so) sesquioxides. Cubic gadolinium oxide provides a midseries lattice heat capacity approximation at relatively high temperatures... 

The series of 15 elements, lanthanium to lutetium, is known as the lanthanide series. These elements all form trivalent ions in solution quadrivalent oxidation states of cerium, praseodymium, and terbium, and bivalent states of samarium and europium are also obtained. 

Abstract This chapter discusses the chemical and physical properties of the lanthanides, some of which are in a certain way peculiar. It discusses the oxidation states of the REE, and the phenomenon called the lanthanide contraction (meaning that the atomic radius decreases with increasing atomic number in the series lanthanum-lutetium). It lists the isotopes known per element, and explains the radioactivity of promethium, the only element of the rare earths that has only radioactive isotopes and no stable isotopes. Magnetism and luminescence also are discussed. 

The removal of 4f electrons is indeed essential in most oxidation states of these elements, which have the tendency of attaining the stable electronic configuration of La or Xe. In the middle of the series, gadolinium is considered rather stable because of the half--filled 4f subshells. It represents, as La and Lu, a sort of reference element for some regular changes in the chemical behaviour, such as an abnormal valency state. As a matter of fact, all three have one 5d electron besides zero, seven and fourteen 4f electrons (which make empty, half-fulled and fully filled the 4f shells, respectively). Therefore, Ln(III) ions correspond to a stable electronic structure 5s p. Lanthanum and lutetium, together with yttrium, could be formally assumed as d elements (see Tab. 2). 

The electronic configurations 5f or 4f representing the half-filled f shells of curium and gadolinium, have special stability. Thus, tripositive curium and gadolinium, are especially stable. A consequence of this is that the next element in each case readily loses an extra electron through oxidation, so as to obtain the f structure, with the result that terbium and especially berkelium can be readily oxidized from the III to the IV oxidation state. Another manifestation of this is that europium (and to a lesser extent samarium) -just before gadolinium - tends to favor the 4f structure with a more stable than usual II oxidation state. Similarly, the stable f electronic configuration leads to a more stable than usual II oxidation state in ytterbium (and to a lesser extent in thuUum) just before lutetium (whose tripositive ion has the 4f structure). This leads to the prediction that element 102, the next to the last actinide element, will have an observable II oxidation state. 

There are some vertical chemical similarities between the elements to justify the numbering of the groups within the d-block in the periodic table. For example, in group 3, scandium, yttrium and lutetium all have a common oxidation state of +3. In most cases the three elements in each vertical column have the same outer electron configuration, for example, scandium 3dHs, yttrium 4d 5s and lutetium 5s 6s. ... 

The concepts derived from atomic spectra have been very important in the recent progress of understanding spectroscopic properties and such chemical questions as the deviations of the oxidation state from M(III) and the conditions for metallic character of the compounds. We return to these individual properties specifically dependent on 4f in section 2, and we start with the smoothly varying properties which can be described as if the lanthanide M(III) is a sphere of electronic density gradually decreasing its radius from lanthanum to lutetium. The contributions of quantum chemistry to this, apparently simpler problem, have been much more qualitative than the specifically spectroscopic statements. 

In aqueous media lutetium occurs as tripositive Lu3+ ion. All its compounds are in +3 valence state. Aqueous solutions of all its salts are colorless, while in dry form they are white crystalline solids. The soluble salts such as chloride, bromide, iodide, nitrate, sulfate and acetate form hydrates upon crystallization. The oxide, hydroxide, fluoride, carbonate, phosphate, and oxalate of the metal are insoluble in water. The metal dissolves in acids forming the corresponding salts upon evaporation of the solution and crystallization. 

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