Diazenes , synthesis

Thiolates are strong ligands and a rich coordination chemistry with cobalt(III) exists. Normally, thiols are employed directly in synthesis, and this is the usual entry into their coordination chemistry. However, alternative approaches do appear from time to time, and recently the cobalt-mediated direct thiolation of an aromatic ring in bidentate phenyl(2-pyridyl)diazene using dithiocarbamate ion to produce a coordinated tridentate thiolate has been reported.1034... 

Fragments C-N-N-C and S Diazenes and hydrazines with a sulfur source The reaction of 2,3-diazabuta-l,3-dienes with sources of active sulfur to prepare 1,3,4-thiadiazoles has been reviewed in CHEC(1984) <1984CHEC(6)545>, CHEC-II(1996) <1996CHEC-II(4)379> and Chapter 13.12 in the Houben-Weyl Science of Synthesis <2004HOU(13)349>. 

Aldehydes react with hydrazine hydrate and sulfur in a high yielding one-pot synthesis of 2,5-dialkyl- and 2,5-diaryl-1,3,4-thiadiazoles via a diazene intermediate (see Section 5.10.9.2.1) <1980LA1216, 1983JHC1399>. Although this synthetic procedure is rare, examples can be found in CHEC-II(1996) <1996CHEC-II(4)379>. 

Following a similar approach, the first bis(triorganosilyl) diazene 402 that is stable at room temperature could be obtained.410 Thus, the reaction of (/-Bu2MeSi)HNNH(SiMe/-Bu2) 403, an analog of 399, with 2 equiv. of BuLi has provided (/-Bu2MeSi)LiNNLi(SiMe/-Bu2) 404, whose oxidation with bromine has led to the formation of the diazene /-Bu2MeSiNNSiMe/-Bu2 402 (Scheme 58). Recently, the stepwise synthesis of cyclic and open-chain silyl hydro-xylamines has been reported by Klingebiel < / /.411 14 For hypervalent silyl hydroxylamines, see Section 6.8. 

The characteristics of the HERON transition states for both steps in the thermal decomposition of Ai,Ai -diacyl-Ai,A -diaIkoxyhydrazines facilitate the synthesis of esters. Notably, the alkoxyl group migrations in the internal 8 2 displacement of the 1,1-diazene in the first step, and nitrogen in the second step, do not involve a tetrahedral alkoxide intermediate and both Barton and coworkers and Glover and have utilized... 

Diazadiphosphetidines nomenclature of, 14 3 synthesis of, 14 71 Diazaphosphetidinone, 14 85 1,6-Diazatriptycene, 33 1-2 Diazene, see also Diimide complexes, osmium, 37 260 ligand, 27 227-235 complexes, 27 230-235, 256-257 free state, 27 227-230 in preparation of dinitrogen complexes, 27 222, 232... 

Schultz, Dervan, and co-workers " subsequently reported the synthesis and characterization of the five-membered ring analogue 65. As before, the oxidation of the appropriate hydrazine at 78 °C gave a clear, colored solution of the aminonitrene. This 1,1-diazene absorbs at 497 nm (in CH2CI2) and 487 nm (in 2-propanol). The IR spectrum shows a strong absorption at 1638 cm that disappears on warming to 25 °C. The isotopomer has a vibration at 1612 cm a shift of 26 cm. ... 

The treatment of N-aminourazole (38) with two equivalents of BAIB in DMSO results in imidation of the sulfoxide and oxidation of the urazole ring to give the sulfoximine 39 (Scheme 20) [46]. The preparation of 39 from 38 can also be accomplished stepwise, by isolation of the dihydro sulfoximine intermediate and BAIB-oxidation of this compound in acetonitrile. The sulfoximine 39 was not isolated, but was generated in solution and employed for the synthesis of bicyclic diazenes. 

The synthesis of diazene complexes has been described (Sections V,B, C, and D). It is worth reiterating that no diazene complex has been prepared via reactions of coordinated dinitrogen and no stoichiometric conversion to hydrazine or ammonia has been demonstrated. 

Diazenes, R1-NHC0N=N-C02Me, have been reacted with 1,3-dicarbonyl compounds (R2COCH2COR3) to give a convenient synthesis of highly substituted 2-imidazolin-2-ones (57) the products are easily dehydrated in the presence of acid 221 Intermediate Michael adducts are isolable. 

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