Acyclic trialkyldiazenium cation chemistry. Thermolysis and solvolysis of 1,2-di-tert-butyl-1-ethyldiazenium perchlorate

Abstract

The thermolysis, ethanolysis, and ethanolysis with 2,6-lutidine reactions of 1,2-di-ferZ-butyl-1 -ethyldiazenium perchlorate (3) are reported. Clean first-order kinetics were observed for these reactions. The reactivity of 3 was found to be nearly the same for the various reaction conditions. Thermolysis of 3 yielded acetaldehyde ierz-butylhydrazonium perchlorate (4) and isobutylene (5) as products. Ethanolysis gave 4, 5, ethyl teri-butyl ether (6), acetaldehyde diethyl acetal (7), and mono-Zert-butylhydrazinium perchlorate (8). For ethanolysis with lutidine, the products were 5, 6, 7, trans-\,\-dimethylazoethane (10), and 1,2-di-ZerZ-butylhydrazinium perchlorate (11). The kinetic and product results for both thermolysis and ethanolysis are rationalized by a mechanistic sequence involving as key first steps a prototropic rearrangement of diazenium cation 3 to an ¡minium cation 14, which subsequently ionizes to ierl-butyl cation (13) and acetaldehyde zeri-butylhydrazone (12). For ethanolysis with lutidine, two separate competing mechanistic processes are indicated. One pathway involves direct ionization

Synthesis, Structure, and Reactivity of Diazene Adducts: Isolation of iso‐Diazene Stabilized as a Borane Adduct

“…In the solid state, iso-diazene adduct 7 is thermally stable up to 104 8C, whereas it slowly decomposes in solution, even at ambient temperatures (see nitrene reactivity of adducts below); this prevented NMR characterization of 7 at ambient temperatures. However, adduct formation was also deduced from low-temperature 19 F and 11 B NMR experiments, which displayed an upfield shift of Dd = 63 ppm relative to free B(C 6 F 5 ) 3 (d (7) = À4.4 ppm). It should be noted that dimerization of the iso-diazene to form a tetrazene was not observed (see below).…”

“…11 B and 19 F NMR spectroscopy are particularly well-suited to distinguish between three-coordinate boron and the four-coordinate boron found in the Lewis acid-base adducts. [41,42] As depicted in Figure 2, the completeness of the reaction can be monitored by 19 F NMR spectroscopy, which clearly indicates the formation of the adduct. Also, 11 B NMR experiments are a suitable tool to detect adduct formation because the signal of the free borane is shifted by about d = 59 ppm upon adduct formation (B(C 6 F 5 ) 3 in CD 2 Cl 2 : d = 59.1 ppm, 4 in CD 2 Cl 2 : d = À0.2 ppm).…”

“…The formation of hydrazinoborane 11 from diazene species 9 led to the assumption that 11 first isomerizes to give an iso-diazene species, which could be isolated from the reaction of 5 with B(C 6 F 5 ) 3 to yield iso-diazene 7. Next, the nitrene reactivity of this transient intermediate iso-(Me 3 Si) 2 N=N·B(C 6 F 5 ) 3 , which could not be isolated but was assumed on the basis of 19 F NMR spectroscopy (Scheme 6, Figure S22 in the Supporting Information), led to the analo- Table 3. Table 3.…”

“…All solvents were dried, freshly distilled, and degassed prior to use. NMR spectroscopy ( 1 H, 13 C{ 1 H}, 11 B{ 1 H}, 19 F{ 1 H}, 29…”

“…These salts were prepared from the corresponding diazene and AgBF 4 in the presence of RI (Scheme 2). [17][18][19][20] In the 1960s, Gutmann and Steininger studied the formation of different Lewis acid diaryl diazene adducts in solution on the basis of IR and UV spectroscopy, however, no characterization in the solid state was performed. [21,22] Aryl-substituted 1,2-diazenes (azo compounds), which are stabilized by a conjugated p-electron system, have been extensively investigated and represent a class of stable compounds, whereas much less is known about alkyl-or silyl-substituted diazenes R 1 ÀN=NÀR 2 .…”