Thallium coordination chemistry

Organometallic Cluster Complexes), and seems to be the most active research field of thallium coordination chemistry. 

In this review, primarily the developments in thallium coordination chemistry since the early 1980s will be surveyed. CCC (1987) is an excellent reference source for work prior to that time. In general, organometallic compounds are outside the scope of this article. There are several useful review and reference articles that describe thallium chemistry, including organothallium work. " " " Thallium is an important element in the field of high-temperature superconducting materials." ... 

As with indium, the literature contains a number of surveys of the general inorganic1 and organometallic chemistry of thallium,273 and the reviews of this element already cited are also concerned with the adducts of the halides and pseudohalides,5 and with other aspects of the coordination chemistry.6 A monograph by Lee provides a most useful treatment of the literature up to 1970.274 The application of thallium compounds in organic synthesis has been discussed.275 276... 

The oxidizing properties of thallium(III) in both aqueous and non-aqueous media obviously preclude the existence of a number of compounds analogous to those found for aluminum, gallium and indium in this oxidation state. Thus, while there is much richer chemistry for thallium in the +1 state, there is a concomitant decrease in the detailed information on thallium(III) coordination chemistry. 

Cationic complexes of Tl3+ with oxygen donors are known, and can be regarded as substitution products of [T1(C)H2)6]3+ (c/. Section 25.2.8.3.1). The DMSO product has been characterized with various anions,403 and there seems no reason to suppose that similar compounds cannot be prepared with donor ligands which are resistant to oxidation. The cation [Tl(pyNO)8]3+ (prepared as the perchlorate) may be an indication that eight-coordinate compounds are also accessible in thallium(III) chemistry.404... 

Aluminum Inorganic Chemistry Cadmium Inorganic Coordination Chemistry Chromium Biological Relevance Hard Soft Acids and Bases Lead Inorganic Chemistry Mercury Inorganic Coordination Chemistry Mercury Organometallic Chemistry Thallium Inorganic Chemistry. 

Coordination OrganometalUc Chemistry Principles Electron Transfer Reactions Theory Macrocyclic Ligands Metal Ion Toxicity Oxides Solid-state Chemistry Polynuclear Organometallic Cluster Complexes Sulfur Organic Polysulfanes Thallium Organometallic Chemistry. 

Thallium has the electronic configuration of [Xe]4/ " 5if 6i 6/), and forms compounds in the oxidation states I, II, and III. Thallium(II) derivatives are relatively rare. In general the bonding between T1(III) and a donor is more covalent in nature, whereas T1(I) compounds show more ionic behavior. Interactions between the T1(I) atoms of neighboring molecules are common. The theoretical explanation has been controversial." The coordination chemistry of T1(III) is complicated by the highly oxidizing power of thallium(III) in both aqueous and nonaqueous solutions. 

A comprehensive review has described the coordination chemistry of NHC analogues featuring boron, aluminium, gallium, indium, thallium, silicon, germanium, tin, or lead as the central low valent atom. ... 

The Tl -Tl relationship is therefore a dominant feature of thallium chemistry. The standard reduction potentials at 25 °C and unit activity of H+ are TIVtI = —0.336 V, T1 /T1 = +0.72 V, and Tl /Tli = +1.25V. Estimates have also been made for the couples T1 /T1 = +0.33 V and Tl /Tl = 2.22 V. The generally valid limitations concerning the use of standard electrode potentials to predict the redox chemistry of real systems are especially important in the case of thallium factors such as complex formation in the presence of coordinating anions or neutral ligands and pH dependence due to hydrolysis do affect the actual or formal redox potentials. For example, redox potentials have been measmed for TICI/TICI3 =+0.77 V in IM HCl and T10H/T1(0H)3 = —0.05 V in alkaline soluhon. These formal potentials differ from the standard value for Tiin/Tii = +1.25 V. The difference can be attributed to the substanhal difference between the complex forming abilities of Tl and Tl , which will be discussed in detail later. The... 

Fluoride, chloride, bromide, and iodide derivatives of thallium(I) are well known. Their solubilities and photosensitivity are similar to the corresponding silver(I) systems. TIE is water-soluble, whereas the chlorides, bromides, and iodides are water-insoluble solids. This property is exploited in ligand-transfer chemistry involving thallium precursors. Some solid-state structures of thal-lium(I) salts of weakly coordinated anions show TT -halide interactions. Selective abstraction of a fluoride from a C-F bond, leading to thallium fluoride, has been described. The compound [ P(CH2CH2PPh2)3 RuH( 7 -ClTl)]PF6 represents the first metal complex containing an 77 -Cl-bonded TlCl ligand. This compound act as a thallium(I)-ion carrier. 

Among the heavy post-transition metals there is a definite reluctance to exhibit the highest possible oxidation state. For example, boron is always trivalent, but thallium shows significant chemistry of the +1 oxidation state, leaving a pair of electrons coordinatively inert. This is known as the inert pair effect... 

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