Tellurium transition metal complex

It is evident from the above table that a considerable spread of chemical shift values is observed in tellurium-transition metal complexes, but the factors that determine the chemical shift are still poorly understood and data are not available for all known structural types. The most extensive compilations of data have been provided by Rauchfuss (187) and Herrmann (191), with the point being made in the former reference that chemical shifts are extremely sensitive to changes in cluster geometry. In principle, 12sTe NMR spectroscopy is a valuable method for studying tellurium-transition metal clusters in solution, but it is clear that more data are required before unambiguous structural assignments can be inferred. 

Although the preparations of transition metal complexes with tellurium ligands often involve similar methods to those used for the synthesis of analogous selenium compounds, the ligand chemistry of tellurium has by no means achieved the scope of that now known for selenium. 

Binary tellurides are generally solid crystalline substances at room temperature. The most common structural classes have been presented in Table 4. The telluride bulk materials are commonly prepared by the direct reaction between the elements. In recent years, low-temperature routes from transition metal complexes with tellurium-containing ligands are being sought for. 

In contrast to alkali metals or transition metals, complexation of [R2P(E)NP(E )PR 2] with main group elements is less well documented. Syntheses and structures of a number of tellurium complexes Te[R2P(E)N-P(E )PR 2]2 (E = S, Se) have been reported. It has been argued that electronic rather than steric effects control the geometry around the central tellurium atom. As examples four-coordination in (79) and two-coordination in (80). ... 

Miscellaneous capping agents X are used for LRP. Examples are listed in Scheme 7.2. They include sulfur compounds (Schemes 7.2a and 7.2g), stable nitroxides (7.2b),stable nitrogen and carbon compounds (7.2c),transition metal complexes (7.2d), iodine (7.2e), halogens with transition metal catalysts (7.2f), and tellurium, stibine, and bismuth compounds (7.2h)." ... 

The aim of this chapter is to review the chemistry of chalcogenolates in the last 10 years. The more recent reviews in this field included chalcogenolates of the s-block elements,13,14 early transition metal thiolates,15 metal complexes with selenolate and tellurolate ligands,16 copper(I), lithium and magnesium thiolates,17 functionalized thiolate complexes,18 19 pentafluorobenzenethiolate platinum group compounds,20 tellurium derivatives,21 luminescent gold compounds,22 and complexes with lanthanide or actinide.23... 

The structural chemistry of some metal dithiocarbamates, i.e. systematics, coordination modes, crystal packing, and supramolecular self-assembly patterns of nickel, zinc, cadmium, mercury,363 organotin,364 and tellurium,365 366 complexes has been thoroughly analyzed and discussed in detail. Supramolecular self-assembly frequently occurs in non-transition heavier soft metal dithiocarbamates. Thus, lead(II),367 bismuth(III)368 zinc,369 cadmium,370 and (organo)mercury371 dithiocarbamates are associated through M- S secondary bonds, to form either dimeric supermolecules or chain-like supramolecular arrays. The arsenic(III)372 and antimony(III)373 dithiocarbamates are... 

Inversion at sulfur (also selenium and, occasionally, tellurium) coordinated to Pt(II), and indeed to a number of other transition metal centers, e.g., W(0), Re(I), Rh(III), and especially Pt(IV), has been studied extensively over several decades (246). Observation of the kinetics of such processes is often complicated by concurrent changes elsewhere in the complex, for example by hindered rotation about C-S in the square-planar complexes [(XS)2Pt(p-SX)2Pt(SX)2]2 with X = C6F4H, CgF5, C6F4(4-CF3). Resolution of the observed kinetics here indicated barriers (AG ) of between 54 and 59kJmol-1 for inversion at coordinated sulfur, between 40 and 60 kJ mol-1 for the hindered rotation (247). 

The sulfide group forms a large number of complexes where it is in chelation with a different heteroatom. Among the common heteroatoms are N, P and As. These complexes are too numerous to list here, but individual complexes can be found from Table 9 or from refs. 1224 and 1667. It is also possible to synthesize compounds which will form bi-, tri- and tetra-dentate complexes to platinum(II), where sulfur, selenium and tellurium.are the only atoms which coordinate to the metal. A review of complexes formed from ligands of the type RS(CH2) SR has been recently published.1734 This article outlines the synthesis, reactions and spectroscopy of these complexes, and allows the complexes of platinum to be placed in context with those of other transition metals. 

The scarcity of compounds involving the heavier main-group elements and the early transition metals, apparent in previous discussions, is also apparent in the chemistry of tellurium. Thiele (147) has described the preparation of the zirconium complex [ Zr(C5Me5)2(/i-Te) 2], 152, from a divinyl complex... 

Many reviews have covered the chemistry of transition-metal, main-group compounds,5-12 and because the title subject is too vast to be covered fully in this review, emphasis will be given to complexes containing selenium and tellurium reference to compounds containing sulfur will be included for purposes of comparison. 

Diethyl(ethylene)tellurourea formed complexes with chromium, molybdenum, tungsten, and manganese carbonyls, in which the tellurium is coordinated to the transition metal The solid complexes are moderately stable in air. They do not decompose when stored in the dark at 20° under an inert atmosphere. A toluene solution of the chromium complex at 20° deposited tellurium forming the chromium-carbene complex. ... 

The osmium carbyne complex 115 reacts with elemental sulfur, selenium, and tellurium to afford the complexes 135 in which the element atoms "bridge the metal-carbon triple bond [Eq. (123)] (56). Complex 115 also reacts with transition metal Lewis acids such as AgCl or Cul to give dinuclear compounds with bridging carbyne ligands. Reaction with elemental chlorine results in addition across the metal-carbon triple bond to generate the chlorocarbene osmium complex 136 [Eq. (124)]. 

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