Thallium I Amides

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- 

The reaction of [(Bu NP)2 Bu NLi(thf) 2] with TlCl in a PhMe/thf mixture yielded the dimeric thallium(I) amide [(Bu NP)2fBLi TI)2l. which has a heterocubane type structure (Tl... Tl distance is 3.546(3) A) with Tl—N bond lengths between 2.55 and 2.62 A. The silylamido ligand in the dimeric complex [ (Me2Si)2(NBu )4 Tl2] results in a 

while the second thallium ion is three-coordinate with an additional interaction with the pyridyl nitrogen atom (Tl—N distance is 2.468(15) A). The metal-metal interaction occurs between the three-coordinate thallium ion of one molecule and the two-coordinate thallium ion of a neighbouring dimer. 

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Like thallium(I) amide from which it is derived by treatment with potassium amide in liquid ammonia, the ammoniated salt (x = 2 or less) explodes violently on heating, friction, or contact with dilute acids or water. 

The first well characterized thallium(I) derivative of a monodentate amide ligand was the silylamide [ TlN(SiMe3)2 2] obtained from LiN(SiMe3)2 and TlCl in toluene. It is a centro-symmetric dimer with an almost perfectly square planar TI2N2 core as shown in Figure 8.12. ... 

Solvent-free hypersilanides have been shown to be useful reagents for the preparation of other especially low coordinated hypersilyl derivatives. The thallium(II) compound 6 [1] or derivatives of divalent tin 7 [3] and lead 8 [3] were synthesized via the reactions of (Me3Si)3SiRb (4) with the bis(trimethylsilyl)amides of thallium(I), tin(II), and lead(II), respectively. 

In this case, the modified Heck reaction of amide 220 bearing fully protected functional groups, which was prepared from 5S,6S-bis(methoxy-methoxy)-4-(4f )-azidocyclohex-2-enone, is a key step. The protected amide 220 underwent intramolecular cyclization with palladium acetate in the presence of thallium(I) acetate and l,2-bis(diphenylphosphono)ethane... 

Only a few A-tritiomethylation reactions of amides have been published so far. As the amide nitrogen is less nucleophilic, the amide function must be activated by deprotonation (NaH, thallium(I) ethoxide etc.) as illustrated by the labeling of332 and 333. obtained in 40-75% yields (Figure 4.91). 

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