A vibrational assignment for pyrazole

Abstract

Infrared spectra of pyrazole in the vapour and solid states and in solution are reported and discussed. From these, and by comparison with the spectra of N-deuterio-, 3-methyl-, and 3,5-dimethyl-pyrazole, and other simple fivemembered heterocycles, a vibrational assignment is proposed.A VIBRATIONAL assignment for the unsubstituted pyrazole nucleus has not yet been discussed. Bonino and Manzoni-Ansidei reported the Raman spectra of pyrazole and some methyl derivatives,l Mirone and Vampiri the infrared spectrum of 3,5-dimethylpyra~ole,~ and Zerbi and Alberti the infrared spectrum of some monoand poly-alkylpyrazoles without a complete discussi~n.~~The structure of pyrazole in the solid and vapour phases is well established, from X-ray analysis5 and microwave spectroscopy,6 respectively. EXPERIMENTALInfrared spectra (4000-600 cm.-l) are reported for pyrazole (m. p. 70") in the vapour phase, in solution, and in the solid phase at room and liquid-nitrogen temperatures, for N-deuteriopyrazole and 3-methylpyrazole (b. p. 2 0 0 -204") in the vapour and liquid phases and in carbon tetrachloride solutions, and for 3,5-dimethylpyrazole (m. p. 107") in the solid phase and in carbon tetrachloride.N-Deuteriopyrazole was obtained by exchange in D,O solution, followed by evaporation under reduced pressure.

Surface Reactivity of Iron Oxide Pigmentary Powders toward Atmospheric Components: XPS and Gravimetry of Oxygen and Water Vapor Adsorption

“…The equilibrium uptakes of both adsorbates at 25ЊC rich surfaces. We quote, for example, the IR results for and a dynamic vacuum of 10 06 Torr are much less than the oxygen adsorption on calcined a-Cr 2 O 3 (23)(24)(25). On the N 2 monolayer capacities of the adsorbents; oxygen-poor surfaces of FeO, no oxygen EPR signal was c. The nitrogen-pretreated powder has stronger adsorptive observed (26), and this has been interpreted to mean that interactions with oxygen than with water molecules; and oxygen is chemisorbed as a mononuclear O 20 species.…”

“…The absence of detectable nitrogen-containing species on IP(N) may well relate to the absence of water vapor and oxygen in the preparative gas atmosphere. In this regard, it is worth referring to the work of Al-Mashta et al while the high-energy component may be attributed to ad-of previous IR studies (22,25), the bi-nuclear species sorbed mono-and/or bi-nuclear oxygen species (e.g., the (O …”

N2O Reduction by the μ4‐Sulfide‐Bridged Tetranuclear CuZ Cluster Active Site

“…[13] Additional terminal oxygen coordination to metal sites has also been implicated in the formation of the {Ru(N 2 O)Ru} dimer [10,14] and has been spectroscopically identified in N 2 O adsorption on a-Cr 2 O 3 . [15] The reduction of N 2 O in biological systems is accomplished by the multicopper-center containing enzyme nitrous oxide reductase (N 2 OR). This reaction is the last step of the denitrification process, where the denitrifying organisms utilize oxidized forms of nitrogen in place of oxygen as the terminal electron acceptors for anaerobic respiration (Figure 1) that is coupled to ATP synthesis.…”

Influence of surface preparation on oxidation of stainless steels at high temperature

“…Low-intensity bands at 1240 cm-' and in the range 850-1000 cm-' (more exactly at 890 and 980 cm-') may be unambiguously associated with an LO mode of SiO, 24 and Cr(V1) or chromate-like groups. 25 The oxidation mechanism of polished samples (Figs 2 and 3) may be interpreted as follows: (1) At the beginning of the oxidation process of a stainless steel a band at 690 cm-' (690-700'cm-') and a shoulder at 725 cm-' are usually observed ( Fig. 2(a) and 3(a)) and are respectively attributed to the higher LO modes of a chromium spinel phase (probably MnCr,O, according to x-ray diffraction measurements) and cx-Cr,O,.…”