Partial interpreter trace

The molecular orbital description of the bonding in NO is similar to that in N2 or CO (p. 927) but with an extra electron in one of the tt antibonding orbitals. This effectively reduces the bond order from 3 to 2.5 and accounts for the fact that the interatomic N 0 distance (115 pm) is intermediate between that in the triple-bonded NO+ (106 pm) and values typical of double-bonded NO species ( 120 pm). It also interprets the very low ionization energy of the molecule (9.25 eV, compared with 15.6 eV for N2, 14.0 eV for CO, and 12.1 eV for O2). Similarly, the notable reluctance of NO to dimerize can be related both to the geometrical distribution of the unpaired electron over the entire molecule and to the fact that dimerization to 0=N—N=0 leaves the total bond order unchanged (2 x 2.5 = 5). When NO condenses to a liquid, partial dimerization occurs, the cis-form being more stable than the trans-. The pure liquid is colourless, not blue as sometimes stated blue samples owe their colour to traces of the intensely coloured N2O3.6O ) Crystalline nitric oxide is also colourless (not blue) when pure, ° and X-ray diffraction data are best interpreted in terms of weak association into... 

Hf-isotope ratios also fall close or within the field of crustal rocks (Fig. 2.4 Table 2.2). This has been interpreted as evidence that metasomatic modification of lamproitic mantle sources in Tuscany was provided by addition of crustal material (e.g. metapelites). Interestingly, the mantle-normalised incompatible element patterns of Tuscany lamproites are similar to those of gneisses and schists in almost eveiy detail. This has been interpreted as evidence for addition of bulk upper crustal material to the mantle, with little element fractionation during metasomatism and the subsequent partial melting (Peccerillo 2002). This makes the Tuscany Province a zone where the upper mantle magmas look very much like the upper crust in terms of trace element and radiogenic isotope compositions. 

Figure 4. A partial trace including descriptive comments for the functionality "nitro from the interpretation of the spectral data of nitrotoluene.

---