Thallium monomeric

The synthesis and characterization of the monomeric amidinato-indium(I) and thallium(I) complexes [Bu C(NAr)2]M[But(NAr(NHAr)] (M = In, Tl Ar = 2,6-Pr2CgH3) have been reported. Both compounds were isolated as pale yellow crystals in 72-74% yield. These complexes, in which the metal center is chelated by the amidinate ligand in an N, j -arene-fashion (Scheme 33), can be considered as isomers of four-membered Group 13 metal(I) carbene analogs. Theoretical studies have compared the relative energies of both isomeric forms of a model compound, In[HC(NPh)2]. ... 

Uson, R., Laguna, A., Abad, J.A. and Dejesus, E. (1983) Preparation Of Monomeric Neutral Or Anionic Tris (Polyfluorophenyl)-Thalbum(III) And Of Anionic Heteronuclear Tris (Polyfluorophenyl)-Thallium Metal-Carbonyl-Complexes. Journal of the Chemical Society, Dalton Transactions, (6), 1127-1130. 

The only thallium compound to be discussed here is the Tlf,Cl2[Si(CMe3)3]6 cluster 61. This remarkable compound was formed by the reaction of thallium) 111) chloride with NaSi(CMe3)3 [Eq. (28)] and precipitated in the form of black crystals in 21% yield, when a solution in toluene was stored at —25 °C for six months [92], Solutions of 61 in benzene decompose slowly at room temperature by the formation of ClSi(CMe3)3 and a black, not identified precipitate. The structure of 61 consists of two four-membered T13C1 heterocycles, which are connected by one Tl-Tl and two Tl-Cl bonds. A monomeric TI3CI heterocycle was isolated as a byproduct in which one thallium atom was bonded to two Si(CMe3)3 substituents. 

Monomeric thallium(I) amides and related species have also be obtained by using chelating amido or related ligands, as in the p-diketiminato complexes [Tl( NDippC-(R) 2CH)] (R = CH3 or (T ) " and TIL (L = N(SiMe3)C(Ph) 2CH or N(Dipp)C-... 

In contrast to the behavior of comparable aluminum, gallium, and indium compounds, the hitherto known alkynyl thallium(III) compounds (170) of the type R2T1C=CR show no tendency to dimerize via n complexation. Molecular weight determinations performed in aniline show the monomeric character of these species, which behave as weak electrolytes due to partial dissociation into R2T1+ and C=CR" (170). 

The needle modification of (PhCH2)5C5Tl, on the other hand, consists of an almost linear chain (Cp Tl—Cp 176°) of monomeric molecules with covalent thallium-cyclopentadienyl interactions (Tl—Cp 249 pm, see Fig. 10). The nonbonded Cp Tl distance is 488 pm (108). There is a certain similarity to the structure of (i -H5CJ)Co(/i-i/s-Me4C2B2C)Tl... 

Unklar ist die Struktur der Thallium-Verbindungen. Eine einfache monomere Struktur ist hier nicht moglich. 

The thallium(III) halides, TIX3 (X = Cl, Br, I), form complexes with amines (L)with formulas TDCs -Ln, where n = 1-3. Among the most studied complexes with this ligand stoichiometry are the neutral monomeric species TIX3 L2, where X = Cl or Br, the halide-bridged dimers... 

There are several early reports that describe the synthesis and characterization of monomeric [Tl(l,l-S2PEt2)] and dimeric [T1(1,1-S2CNR2)]2 [R = Me, Et, -Pr, i-Pr, n-Bu or i-Bu) thallium (I) adducts.The synthesis of the first thallium(I) polysufides and chalcogenide cages has been described. The two-coordinate T1(I) compound [Pt2Tl(/i3-S)2(PPh3)4]X (X = NO3 or PFg)... 

I.r. spectra of the vapour over indium and thallium metaborates can be assigned to monomeric species MB02, which have a cyclic structure (76).556... 

The structures of four tri-t-butoxysilanthiolates 210-213 have been reported. Whereas 210 is tetrameric with a nearly planar eight-membered ring, 211 and 212 are dimeric. In addition to the two thiolate S atoms the thallium atoms in 211 are also coordinated, albeit more weakly, by one butoxy O atom at a distance of 2.799(4) A. A similar (2+1) coordination is found for the mercury atoms in the monomeric species 212 [d(Hg-O) = 2.878(4) A]. Remarkably short Si-S distances are found in 213 and, in particular, 211 [2.078(2) A], suggesting that the M-S bonds (M = Pb, Tl) may exhibit a marked degree of ionicity in these compounds. 

---