Infrared stretching frequencies for

Infrared vibrational energies of ligating groups such as CO, N2, NO or RNC (R = alkyl or aryl) have been extensively correlated with redox potential data.28 37""41 For a series of closely related mononuclear complexes it is generally observed that as E° (or EVl) for the oxidation of members of the series becomes increasingly positive, then v, the infrared stretching frequency for the (ter-... 

Infrared stretching frequencies for a range of 2-aryl-6-phenyl-47/-thiopyran-4 -ones, -thiones, and oximes and some related 1-oxides and 1,1-dioxides have been reported (Table 14) <1993PS(81)101>. 

Table 9 Infrared stretching frequencies for exocyclic double bonds on small rings...

From the structural viewpoint, HNO displays a bent structure with the N atom as the central one and an H—N=0 angle of about 109°. The N—O bond distance is predicted to be 1.211 A which is, as expected, larger than the N—O bond distance in nitric oxide due to the addition of electron density to the n orbital. Due to this fact, the NO infrared stretching frequency for HNO is ca. 200 cm smaller than for nitric oxide. 

We illustrate the sensitivity of the C-0 stretching frequency for the bonding configuration with a perhaps somewhat dated but still very instructive study of the adsorption sites of alloy surfaces. Soma-Noto and Sachtler [18] reported an infrared investigation of CO adsorbed on silica-supported Pd-Ag alloys some of their spectra are shown in Fig. 8.5. On pure palladium, CO adsorbs mainly in a twofold position, evidenced by the intense peak around 1980 cm 1, although some CO appears to be present in threefold and linear geometries as well. This is a common feature in adsorption studies on supported catalysts, where particles exhibit a variety of surface... 

For the detection of subtle differences within a given series of closely related compounds, spectroscopic studies are generally more useful than diffraction studies. An inverse correlation between the C=C bond lengths and the infrared stretching frequencies, vc-c, in a series of ethylene complexes has been observed (63) (Fig. 5A). There is at present some discussion about the nature of the infrared band observed around 1500 cm-1 [(70) and referen3es therein]. It is found that the normal mode contains... 

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