Organometallic azides

The second contribution by A. Devi, R. Schmid, J. Muller and R. A. Fischer entitled Materials Chemistry of Group 13 Nitrides reviews the organometalHc precursor chemistry of group-III nitride OMCVD. The authors discuss the various efforts undertaken in the past decade to come up with alternative precursors to compete with the classical system of Ga(CH3)3 and NH3 to grow GaN, which is commercially employed in industry. The potential of the rather exotic organometallic azide compounds as precursors for the nitride materials is critically discussed, showing the limitations and prospects of that approach as well as representing one of the few examples of comprehensive studies on... 

Organometallic azides of the type [(Ph)3P]2M(N3)2 (M = Pt, Pd) react with CS2, probably with formation of 5-mercaptothiatriazole complexes.43... 

Trialkyl-silicon- (253) and -tin-1,2,3-triazoles (254) are obtained readily from organometallic azides and alkynes. These adducts are hydrolyzed smoothly in almost quantitative yield to give (255) <66cb2512, 72jom(44)117) (c/. acylation via 2-TMS derivatives, Section 4.11.4.5). 

The reactions of covalent azides with the isocyanate system are summarized in Scheme 41. Addition of organic azides and azide ion to isocyanates occurs at the —N=C— bond and gives 1,4-disubstituted tetrazolin-5-ones (221 Scheme 41). The reaction of organic azides with isothiocyanates is a complicated reaction giving a mixture of five different products of which the tetrazoles (223) are minor constituents and the remaining compounds are sulfur heterocycles. Organometallic azides, and also azide ion, add to the —N=C—... 

It is not surprising that organometallic azides such as 2 and 3 still can be characterized by a band in the infrared spectrum at 2050-2100 cm- ... 

The physical and chemical properties of the inorganic azides have been extensively reviewed [4-11], Richter [12] has discussed the chemical classification of azides as (i) stable ionic azides, (ii) heavy-metal azides and (iii) unstable covalent azides. This classification is based on the percentage ionic character of the metal-azide bond, tabulated as formal ionicities in [12]. For example, the Na-Nj and Ba-Nj bonds are 70% ionic, but Pb-N, is only 34% and H-Nj is 22%. Bertrand et al. [13] have reviewed the photochemical and thermal behaviour of organometallic azides. Richter has also given [12] an excellent review of the methods of preparation of HNj and other azides. He criticizes early workers for inadequate purification and characterization of their starting materials and their neglect of allowance for the possible formation of hydrates (e.g., barium azide may be present as Ba(N3)2.1. SHjO below 284 K, forms a monohydrate between 284 and 325.5 K and is anhydrous above 325.5 K). 

Organometallic azides, for example, tri-n-butyltin azide and triphenyltin azide, also react with phenylisothiocyanate to give N=C adducts [Eq. (18))35°,35i jhe organometallic group could readily be removed to give the 1,5-disubstituted tetrazole by treatment with cold dilute HC1.350 In... 

Organometallic azides add smoothly to acetylenes (Eqs. 40,41), and the resulting 2-trialkylsilicon (2.4-2)" or tin (2.4-3)" derivatives hydrolyze in near quantative yield. The addition of acetylazide to triphenylphosphorane methylenes (2.4-4) followed by hydrolysis (Eq. 42) is another attractive route. Yields of 60% and greater were reported for a variety of substituents on 2.4-5. 

The two reports of the addition of organometallic azides to 4.3-3 show promise for future development (Eqs. 56,57). ... 

Silazarophenanthrenes. 2-Biphenylyldimethylsilyl azide irradiated with a low-pressure Hg-arc 10,10-dimethyl-10,9-silazarophenanthrene. Y 35%. — This is the first example of insertion into a G-H-bond by monovalent nitrogen from an organometallic azide. J. M. Gaidis and R. West, Am. Soc. 86, 5699 (1964). 

Organometallic azides do not have the characteristics of explosives (e.g., triethyl lead azide) [3]. 

Boyd DC, Haasch RT, Mantell DR, Schulze RK, Evans JF, Gladfelter WL (1989) Organometallic azides as precurstffs for aluminum nitride thin films. Chem Mater 1 119-124... 

The organometallic azides largely lack any sensitivity to shock, and are surprisingly thermally stable thus triphenyltin azide decomposes around 300°C, to tetraphenyltin and... 

The organometallic azides of lead(IV) are more stable and have been widely studied The types R3PbN3 and R2Pb(N3)2 are obtained by the action of hydrazoic acid upon R3PbOH or R2PbO. 

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