Nitrogen solid infrared spectra

This moderately air-sensitive niobium salt is soluble in a wide variety of solvents, such as aromatic hydrocarbons, ethers, ketones, alcohols, and water, to give very air-sensitive solutions. The solid is also somewhat light-sensitive and should be stored in the dark. It is indefinitely stable at room temperature under nitrogen. The infrared spectrum of the compound in the carbonyl region is given in Table I. 

Diiodo tris(3,5-dimethylpyrazolyl)hydroborato molybdenum(III) is an air-stable, black, crystalline solid that dissolves in chloroform, dichloromethane, and toluene, but is only slightly soluble in hexane. It reacts with alcohols (see below), and is best stored for prolonged periods under dry nitrogen. The infrared spectrum (KBr disc) shows vNO 1700 cm-1 and vBH 2555 cm-1, and the 220 MHz H nmr spectrum in CDC13 shows signals attributable to the pyrazolyl protons at = 6.09 (area 1) and 5.86 (area 2), the phenyl protons at = 7.13, 7.27 (area 5), and the pyrazolyl methyl protons at = 2.77 (area 3), 2.58 (area 3), 2.29 (area 6), and 2.19 (area 6). 

In the infrared, 2-hydroxycyclobutanone has a carbonyl band at 1780 cm in chloroform solution. Kept in nitrogen-filled screw-capped vials in the freezing compartment of a refrigerator, 2-hydroxyoyolo-butanone slowly but completely solidifies as its dimer. The infrared spectrum of the solid in a KBr disk shows no carbonyl. However, a chloroform solution of the solid does show the characteristic 1780 em band, indicating rapid equilibration with the monomer. 

Fredin, L., B. Nelander, and G. Ribbegard. 1977. Infrared spectrum of the water dimer in solid nitrogen. I. Assignment and force constant calculations. J. Chem. Phys. 66,4065. 

The reaction flask is cooled to —78°C., and a 1.05-g. (13.8-mmole) sample of trimethylphosphine, measured as a gas, is introduced. The colorless solution wrhich forms is allowed to warm to room temperature and is stirred for an hour. Solvent is removed slowly under vacuum, and the white solid which remains is pumped for one hour under high vacuum. Dry nitrogen is admitted, and the flask is removed from the vacuum line. The solid product is broken up with a spatula and washed from the flask with ether. It is collected by filtration, washed with 50 ml. of ether in small portions, and allowed to air-dry in the hood for half an hour. Yield is 3.5 g. (87%). The white salt is pure [H2B P(CH8)8 2]+I as judged by its infrared spectrum, but it has a strong trimethylphosphine odor. 

The (1,1-diphenyl) phosphonitrile fluoride trimer is a colorless crystalline solid that melts at 68.5-69.5°C. It can be recrystallized from n-pentane, n-heptane, petroleum ether, or absolute methanol. It is also soluble in diethyl ether, carbon disulfide, and chloroform, but it is insoluble in and not attacked by water. The infrared spectrum shows a strong phosphorus-nitrogen stretching mode at 1250-1265 cm."1. Strong bands at 914-920, 900-906 cm."1 and at 812-820 cm."1 are associated, respectively, with phosphorus-fluorine asymmetric and symmetric stretching modes. 

The complex is obtained as deep olive-green platelike crystals, m.p. 142° (decomposes). The solid compound decomposes slowly on exposure to the atmosphere the process is greatly accelerated if the material is finely divided. The preparation of samples for physical measurements must be carried out in a nitrogen atmosphere. The complex forms very air-sensitive solutions in 1-butanol or nitromethane. The infrared spectrum exhibits characteristic ionic perchlorate absorptions at 1100 and 625 cm, and there are strong ligand bands at 1625, 1400, 575, 500, and 380 cm-i. 

In the solid state at room temperature the compound is stable for only about 1 hr, but it can be stored indefinitely under nitrogen at —20°. The compound should always be handled under an inert atmosphere as it is air-sensitive. Its infrared spectrum consists of strong bands at 1010 and 815 cm-i arising from vibrations of the //-cyclopentadienyl ligand and bands at 1100, 750, 700, and 490 cm-i due to vibrations of coordinated dimethylphenylphosphine. Bands at 1050 and 530 cm i in spectra of the tetrafluoroborate salt or at 830 cm i in those of the hexafluorophosphate salt arise from vibrations of the anion a band at 1740 cm- is due to a niobium-hydrogen stretching vibration. The nmr spectrum (TMS internal standard) at —36° of an acetone-dg solution of the tetrafluoroborate salt is composed of a complex band centered at 72.4, a doublet with Jph = 2.0 Hz centered at t4.42, a doublet with Jph = 7.1 Hz centered at r8.52, and a doublet with Jph = 31.5 Hz centered at t13.96. 

Nelander, B., Infrared. spectrum of the water formaldehyde complex in solid argon and solid nitrogen, J. Chem. Phys. 72, 77-84 (1980). 

Preparation of Osmium Oxide Pentafluoride.—Osmium oxide pentafluoride was made in several ways, (a) Osmium metal was heated in a stream of oxygen and fluorine (1 2 v/v). The reaction was carried out in a quartz tube with the osmium in a nickel boat, and was initiated by the heat from a small flame. Once started, the reaction sustained itself. The product, which was caught in traps at —183°, was a mixture of an emerald green solid and a pale yellow, more volatile, solid. The difference in volatility of the components of the mixture permitted their separation by trap to trap sublimation under reduced pressure, from a trap held at —16° to receivers cooled with liquid nitrogen. The emerald green solid was retained in the —16° trap. The more volatile, yellow, component proved, from its infrared spectrum, to be osmium hexafluoride. The emerald green solid, m. p. 59-2°, established by infrared spectroscopy, to be free of OsFj, amounted to —50% of the product. 

The compound Re4H4(CO)i2 is a very dark red (green by reflected light) crystalline compound that is somewhat air stable in the solid state but should be stored under nitrogen, especially when in solution. The infrared spectrum in the carbonyl region shows only two bands, 2042 and 1990 cm V The H NMR (CCI4 solution) show a resonance at rl5.08 together with the resonances for the solvent of crystallization. The compound reacts slowly with carbon monoxide and instant-... 

Since there are 12 valency electrons in NgHg, Walsh (2) has predicted a bent ground state, existing in either a cis or a trans configuration for diimide. Blau and Hochheiraer (4) have measured the infrared spectrum of diimide which was frozen in a cold trap as one of the decomposition products of N H. The spectrum of the solid at liquid nitrogen temperature agrees with... 

The complex is a yellow, crystalline solid soluble in organic solvents, including hexane. The solid is unstable and decomposes slowly at room temperature and rapidly in solution. It can be stored indefinitely at - 20° under nitrogen. Melting point 36°. TTie infrared spectrum shows v(CO) at 2125(s), 2060(vs), and 2040(vs) (hexane). The complex serves as a useful reagent for the preparation of carbonyl phosphine cobalt(I) complexes, as one or two CO groups can be readily displaced at room temperature by different ligands. 

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