Imido azides

Thiocarbamyl Addes, Imido Azides, and Hydroximido Addes.362... 

Thiocarbamyl Azides, Imido Azides, and Hydroximido Azides. Thio-semicarbazides react with nitrous acid and isothiocyanates react with hydrazoic acid to yield azides of marked stability. For this... 

The effect of a substituent may be substantially modified by fast, concurrent, reversible addition of the nucleophile to an electrophilic center in the substituent. Ortho- and para-CS.0 and pam-CN groups have been found by Miller and co-workers to have a much reduced activating effect on the displacement of halogen in 2-nitrohaloben-zenes with methoxide ion [reversible formation of hemiacetal (143) and imido ester anions (144)] than with azide ion (less interaction) or thiocyanate (little, if any, interaction). Formation of 0-acyl derivatives of 0x0 derivatives or of A-oxides, hydrogen bonding to these moieties, and ionization of substituents are other examples of reversible and often relatively complete modifications under reaction conditions. If the interaction is irreversible, such as hydrolysis of a... 

With the same tactic, a meta-stable 3-coordinate iron(III) imido complex was reported by Holland and coworkers [40]. Using the diketiminate-supported dinitrogen iron(I) complex [L T eNNFeU ] as a source of iron(I) precursor [L = 2,4-bis (2,6-diisopropylphenylimino)pent-3-yl], the addition of adamantyl azide (AdN3) in... 

Other iron-imido complexes have also been reported. Holland and coworkers reported the synthesis of the imidoiron(III) complex [L FeNAd] [40, 41]. This imidoiron(III) complex has not been isolated and was found to convert to a purple high-spin iron(III) complex. It has an S = 3/2 ground state from EPR measurement. Based on the results of QM/MM computations, [L EeNAd] is a three-coordinated complex with an Fe-N distance of 1.68 A and has a nearly linear Fe=N-C unit with Fe-N-C angle of 174.1°. Chirik and coworkers made use of liable ligands to prepare iron-imido complexes by treatment of C PDI)-Fe(N2)2 ( PDI = (2,6- Pr2CgH3N = CMe)2C5H3N) with a series of aryl azides [47]. 

The cobalt(I) complexes also react with organic aryl azides to form the terminal cobalt(III) imido complexes [(TIMEN" OCo(NAr )]Cl (Ar = xyl, mes, R — p-PhMe, p-PhOMe) at —35°C (Fig. 17). These deep-green complexes are fully characterized, including NMR, IR, UV-Vis spectroscopy, and combustion analysis 10). These are diamagnetic (d low-spin, S — 0), and the NMR spectra suggest a Ca-symmetry of these molecules in solution. 

Dibenzyl complexes with calcium, strontium, barium, 2, 120 with Ti(IV), 4, 343, 4, 349 with Zr(IV), 4, 783, 4, 785-786 with Zr(IV) mono-Cp complexes, 4, 833 Dibenzylgallium azides, for semiconductor growth, 12, 17 Dibenzyl imido complexes, with Ti(IV), 4, 352-353 Dibenzyl phosphoranimino carbenes, with Zr(IV), 4, 798 Dibenzyl titanasilsesquioxanes, synthesis, 4, 493 Dibenzyo-tetramethyltetraaza[14]-annulenes, with Zr(IV),... 

Tetraazabutadienes174 as such do not exist but complexes can be formed from reaction of organic azides, RN3, with compounds like Ni(COD)3, by interaction of halides with Li2[PhNN=NNPh], or by 1,3-dipolar cycloadditions with imido complexes.175 The compounds have been variously termed as tetraazadiene, tetra-azene, or tetraazenido. They normally have short and long bonds as in (9-XXXII) but there is doubtless electron delocalization over the ring system. 

Organic azides, RN3, usually react losing N2 to give imido compounds (Section 9-16), but an azide intermediate has been isolated and characterized in the reaction203 ... 

Imido zirconocenes see Imide Complexes) are synthesized from thermolysis of Cp2Zr(Me)NHR. They react with a wide variety of organic substrates (alkynes, imines, azides, carbodiimides, ketones) to yield [2 + 2] cycloaddition products (Scheme 4) see Metallacycle) ... 

Reaction with letramethoxyetkylene. In a reaction that is first order with respect to each of the reacUnts, tetramethoxyethylenc (I) and tosyl azide (2) yield the imido-carbunate (3). These data, as well as cross-over experiments with isotopically labeled (I), exclude any dissociation of (1) into two molecules of dimethoxycarbcnc under the conditions applied. ... 

Acyl azides are easily handled by acetic acid-catalysed Curtius rearrangement which generates one mole of nitrogen per azide This can be done conveniently on a micro scale with no interference from such groups as nitro, nitroso, azoxy, azo, hydrazo, cyano, amido, imido, amino or ammonium. Diazo or A -nitroso groups do interfere. 

The preceding section dealt with imidoyl azides in which the imido function is not part of a heteroaromatic (or otherwise highly conjugated) system. In these cases, the tetrazole turned out to be the thermodynamically favoured isomer. If the imido function is made part of a ring the azide form is often much more stable in many other cases, equilibria between azide and tetrazole forms are established. Lattice energies can make one form exclusive in the crystalline state of compounds, which in solution display an azide-tetrazole equilibrium . 

When the imido-function is made part of a heteroaromatic ring, one might expect the preference for the azide form to be even stronger. However, Reynoldsfound systems of this kind, in which the preferred isomer depends on the nature of the heteroaromatic ring. 

Perhaps the most exotic imidoyl azide, containing the imido function as part of a heteroaromatic system, is b-azidotetrazole, HGN7, the potassium and sodium salts of which are obtained when 1,3-diamino-guanidine (imidocarbazide) is treated with alkali nitrites in acetic acid ". The alkali salts, Na+ and K CN7, are extremely explosive, the free azide less so. It shows the i.r. absorption of the azide group at 2151 cm ... 

Some stable imidoyl azides, with the imido function a part of a heteroaromatic ring, are formed not by simple opening of a tetrazole but by more complicated processes. Scott described the con-... 

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