Large nuclear quadrupole coupling

Nuclear quadrupole coupling constants can thus provide much valuable information about chemical bonding in transition metal compounds since they can be obtained both for the metal and, or for the attached atom in many cases. There are, however, a number of disadvantages inherent in the technique. The resonances are often of very low intensity thus necessitating a large sample size (up to 10 grams). Furthermore, the complete region of interest, 2—1,000 MHz, cannot be covered by one... 

The investigations continued with ArAuX (X = F, Cl, Br). In all instances, the Ar metal distances are now about halfway between the reference van der Waals, r dw, and covalent, rcov, bond lengths (see Table 1). This is accompanied by dramatic changes in the Au nuclear quadrupole coupling constants and large ab initio dissociation energies. Further evidence for real chemical bonds between Ar and Au comes... 

To a first approximation nuclear quadrupole couplings which are smaller than the hyperfine coupling do not influence the shape of the ESR spectra. Exceptions occur for species containing I > Vi nuclei with large nuclear quadrupole moments. We refer to [26] for an analysis of a metal-ion complex by a combined experimental and computational study. Other examples involve species containing halogens such as Cl, Br or I. In the example shown in Fig. 3.20 the principal values of the hyperfine... 

The microwave spectrum of SiCh formed by conproportionation of SiCU and solid Si has been recorded . The large asymmetry of the Cl nuclear quadrupole coupling tensor was accounted for by large rr-electron back-donation from Cl to Si. Emission from the products of reaction of excited P2,0 Ar atoms with SiCLj and with SiH2Cl2 in a EX2 discharge flow system has been attributed to phosphorescence from Bi SiCl2 on the basis of the vibrational spacings . 

---