Mulls hexachlorobutadiene

IR Spectra were measured by a combination of KBr disk and hexachlorobutadiene mull methods. 

In the low energy region the measurements of Alien et al. went down only to 4 kK. but hexachlorobutadiene mull data indicated the presence of a further band at 3.0—3.4 kK.. This and the 5.6 kK. band were therefore readily identified as transitions within the spin-orbit split ground state manifold — the 3 kK. absorption as 3Tig (A) - 3i g (A) and the 5.6 kK. peak as 3Tlg (A) -+3T g (A, A). Allen et al. were unable to resolve the broad band at 30 kK. but it may be noted that six formally... 

Infrared Data. The presence of moisture and/or oxygen bonds is easily detected by infrared analysis, and the spectra serve partly to indicate the type of contamination that might be present in anhydrous or oxygen-free compounds. Tin(II) chloride was studied as a hexachlorobutadiene mull, and molybdenum(V) chloride and molybdenum (III) chloride were studied as Nujol mulls. All starting materials and the final product were free of moisture, OH stretching, and molyb-denum-to-oxygen bonding, as indicated by the absence of absorptions at 3500, 1800, and 900-1020 cm 1, respectively. 

C -(Dimethylpropylamine)carbaundecaborane(12) is a white crystalline solid, m.p. 191-192°. It is very soluble in acetone and tetrahydrofuran, slightly soluble in chloroform and methanol, and insoluble in benzene and water. The infrared spectrum (Nujol and hexachlorobutadiene mulls) contains major absorption bands at 2988(m), 2561(vs), 1481(m), 1472(m), 1414(m), 1130(m), 1035(m), and 934(m) cm. h The proton nuclear magnetic resonance spectrum (acetone-de solution) exhibits... 

Infrared Spectra. Nujol-hexachlorobutadiene mulls were employed to obtain spectra on a Perkin-Elmer Model 21 Spectrophotometer. Spectral data are reported in Table VI. 

Measurements. Infrared spectra in the sodium chloride region were obtained in Nujol and hexachlorobutadiene mulls on a Perkin-Elmer Model 21 Spectrometer. Proton NMR spectra were obtained on approximately 20% by weight solutions at 14,100 gauss on a Varian HI -60 NMR Spectrometer, and are shown in Figure 1. Irradiation of the two POCH methine protons at 294 cps reduced the quartet in C (obtained by expansion of the 821 cps PH peak) to the doublet in A. Irradiation at 114 cps in the methylene region reduced the quartet to the triplet in B. In dimethyl sulfoxide, using Me4Si as an internal standard, the POCH doublet... 

Solid state infra red spectra of air sensitive materials are more conveniently recorded as Nujol or hexachlorobutadiene mulls than as KBr pellets, primarily because the Nujol mull provides a protective coating for the solid material during sample preparation. 

Spectrum of solid can also be obtained from a mull or paste. Some commonly used mulling reagents are (/ ) nujol (/ / ) hexachlorobutadiene or (iii) chlroflurocarbon oil etc. Nujol is the most commonly used reagent which is a mixture of liquid paraffinic hydrocarbons of high molecular weights. Solid samples can also be examined in solutions... 

Material - shall consist of the beta polymorph only as determined by the examination of a 5% muli of the sample in hexachlorobutadiene or tetrachloro-ethylene by means of a Perkin Elmer Double Beam Infrared Spectrophotometer, Model 21. The mull is prepd by grinding the sample one min in dry state and then adding hexachlorobutadiene and again grinding for another min. The spectrophotometer has a drum setting for th e slit of 980. This gives a slit of about 460 microns ac 13.5 microns and a... 

Tlie octogen should consist of -polymorph by examination of a 5% mull of the sample in hexachlorobutadiene or tetrachloroetliylene in a sodium chloride cell. Another sample of pure polymorph is placed in a compensating cell. Tlte absorption is observed between 14.0 and 14,3 p. 

A less aggressive sample preparation method is a mull in which the sample is dispersed in a liquid matrix, most commonly used is the mineral oil Nujol but other liquids may also be used (e.g. fluorolube and hexachlorobutadiene). The sample is ground and mixed with the oil (Nujol) and then sandwiched between two IR transparent (metal halide) plates. Although the sample is less likely to be altered using this technique, the oil has strong absorbance bands which obscure some regions of the spectmm (by using alternatives to Nujol... 

Mulls are prepared by grinding about 1 mg of a solid in a small agate mortar with a liquid hydrocarbon (Nujol, Kaydol, etc.). Nujol is transparent to infim-ed over a very wide range and for this reason Nujol mulls are very widely used. One disadvantage with Nujol is that it gives C—H str and C—H def bands. Thus if C- 1 vibrations are to be studied, Nujol may not be a good choice. For these purposes hexachlorobutadiene. or chlorofluorocarbon oils are used. 

Powders or solids can be examined as a thin paste or mull (mineral oil, nujol, hexachlorobutadiene, perfluorokerosene) or through the pellet technique which allows quantitative analyses to be performed since accurate measurements can be made of the ratio of weight of sample to internal standard in each disk. Modern technique using diamond ATR is removing the need for mulls and disks. 

For obtaining Nujol, Fluorolube, hexachlorobutadiene, etc., mulls of polycrystalline samples under inert gas protection, one can once again use glove boxes. Very often, however, it is more convenient to handle the compounds in small Schlenk tubes. In these tubes manual or vibratory grinding of the substance can be carried out in a current of inert gas. Usually even moderately air-sensitive complexes can be placed between the cell windows in air if the substance is emulgated with Nujol or Fluorolube. 

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