Nitrites: group frequencies

The nitrite group has three fundamental vibrational modes which are all active in the infrared region, and upon coordination the band positions are shifted as compared to the free nitrite frequencies. In Table I the infrared frequencies of the N02 ... 

Table II. Nitrite and Nitro Group Frequencies in Pentammine Co(III)...

Chapter 9 is concerned with functional groups that may contain —N=0 bonds or Si, P, S or the halogen atoms. With the exception of the X—H stretches derived from these elements and the nitroso (—N=0) and nitrite groups (—O—N=0), the large majority of the group frequencies associated with these elements fall below 1500 cm in the fingerprint region of the spectrum (I). 

However, a small study of younger women (16-59 years of age) presenting with a history of two symptoms - dysuria and frequency - but dipstick negative for both leucocyte esterase and nitrites, demonstrated that treatment with short-course trimethoprim significantly decreased the median time to resolution of dysuria (76% of women in trimethoprim group were free of dysuria by day 3 compared with 26% of placebo group). The authors concluded that their results supported the use of symptoms alone to diagnose and treat UTI without urinalysis (Richards et al., 2005). 

In general, there are three regions of the infrared (IR) spectra that merit special attention. Bands in the range 2400-2100 cm can be assigned to the N-N stretching frequency of adsorbed N2 or N20, bands below 1700 cm" can be attributed to oxidized nitrogen species (nitrite, nitrate, and nitro compounds), and those around 3800-3600 cm" to hydroxyl groups.Table 4.1 summarizes the main IR bands identified for a Rh/ceria catalyst in contact with a NgO/He flow. 

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