TmSe

Trimethylsilyl)ethyl (TMSE) Ester RC02CH2CH2Si(CH3)3 Formation... 

TBAF, DMF/THF, 64-100% yield. Cleavage occurs in the presence of TMSE and benzyl esters and acetates. ... 

Monochalcogenides, LnZ (Z = S, Se, Te), have been prepared for all the lanthanides except Pm, mostly by direct combination.They are almost black and, like the monoxides, have the NaCl structure. However, with the exceptions of SmZ, EuZ, YbZ, TmSe and TmTe, they have metallic conductivity and evidently consist of Ln -t- Z ions with 1 electron from each cation delocalized in a conduction band. EuZ and YbZ, by contrast, are semiconductors or insulators with genuinely divalent cations, but SmZ seem to be intermediate and may involve the equilibrium ... 

This reagent was prepared as described above using TMSE-OH and purified by chromatography (silica gel, hexane/EtOAc/TEA 90 10 4) yield 81% 31P NMR (CDC13, 6) 145.1 (CAUTION extensive disproportionation of this reagent occurs during distillation1211). 

A course now well known to secure its revelation is to closely investigate groups of materials which evidently already span the configurational crossover, like TmS-TmTe, or are likely to do so under reasonably attainable changes in applied conditions. TmSe has now proved an excellent example under ambient conditions of this unusual state and its fascinating properties. SmBg was the first material to be discovered in such a state, and SmS/Se/Te reach it, as indicated above, under relatively low pressures. The state is labelled ICF for reasons to become apparent below. 

The form taken by the resistivity rise at low temperatures in the ICF metallic phase has not yet been satisfactorily analyzed. Fig.3 shows that a p a exp relation makes fair representation of the data (38) for SmS at 20 kB. For lOkB, SmS is not properly converted at the lowest temperatures (Ref. 38, inset to Fig. 2) and the sigmoid deviation shown could be ascribed to this cause. However none of the data presently available for ICF metals (e.g. SmBg, TmSe), seems to express an exponential run away in resistivity to low temperatures. It is possible that the observed flattening off marks the limit set by surface conduction, via permanently and fully... 

The crossover in the system (Sm/Th) Se probably will remain second-order, and occur at lower doping content than the second-order crossover in (Sm/La) S ( 30%) 44. It would give clearer lattice parameter information on the course of the crossover through ICF conditions than does the latter system, Th d being smaller than La d. Sr-doping of TmSe could bring about reversion to the / condition also in second-order fashion. 

Fig. 4. Chromatogram obtained for separation of SeCys, SeMet, and TMSe+ (100 xgl 1 as Se) under optimum experimental conditions. Reprinted from Munoz Olivas et al. [54] by permission of The Royal Society of Chemistry.

SeCys, SeMet, TMSe Aqueous matrix The storage in the dark at pH 4.5 in Pyrex containers at both 4°C and 20°C The storage in the dark at 4°C in PP containers 1 year 6 weeks 45 46... 

SCHEME 14.3 Synthesis of mycobacterial lipid II. TMSE, 2-(trimethylsilyl)ethyl. 

Binary and ternary selenides and tellurides show essentially the same behaviour 138, 139) as the sulfides. The situation is rather special142) for the TmSe and TmTe containing, on an instantaneous picture 13) 80 or 50 percent, respectively, of the conditional oxidation state 4f12 Tm[III] and the rest (20 or 50%) 4f13 Tm[II]. 

The stability of SeMet and TMSe+ in freeze-dried oyster and in the enzymatic extracts stored at different temperatures (— 18, 4, and 20°C) was studied. The results obtained for the freeze-dried sample showed that SeMet and TMSe+ were stable for at least 12 months under all the conditions tested. However, Se species in the enzymatic extracts were only stable for 10 days if stored at 4°C in Pyrcx containers [99]. 

Figure 20.1. Se species degradation by MW digestion (160°C) with HN03. A Hamilton PRP X-100 anion exchange column, 20 mM NH4H2P04, pH 6, 1.5 ml min-1, 40°C (a) standards (b) TMSe+ (c) selenocystine (d) selenomethionine.

In the case of thulium compounds TmSe and TmTe and YI3AI3, distinct multiplet structures due to divalent and trivalent thulium are seen in the 4f region [38]. The multiplet structure in TmTe is more distinct than in the case of TmSe in agreement with magnetic susceptibility data, (i.e.) magnetic moment of TmTe is smaller than that of TmSe. 

Fig, 9,25, The multiplet structure of the 4f region in the XPE spectra of TmSe and TmTe, Signals due to divalent as well as trivalent Tm can be seen clearly [38],... 

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