Spin cadmium compounds

Table 4.1-161 Spin-orbit splitting energy Ago of cadmium compounds...

Several isotopes (see Isotopes Isotope Labeling) of Cd are known, and 8 are stable (Table 3). For " Cd and " Cd, the nnclear spin is 1/2 and they are used for NMR studies of Cd compounds and in biological fields (see Cadmium Organometallic Chemistry). " Cd is used in the nuclear industry because of its high neutron cross section. Unstable isotopes are prepared from nuclear reactions. Cd stable isotope composition in geological and meteorite samples has been investigated using multiple collector inductively coupled plasma mass spectrometry. ... 

The 2 NMR-active nuclei of cadmium are both spin I = /2, and have similar natural abundances (12.75% for " Cd and 12.26% for Cd). However, the relative receptivity of Cd is slightly better (see Chapter 1, Table 1.1), making it the nucleus of choice for many Cd NMR studies. Cadmium NMR has proved useful in studies of semiconducting oxide compounds and alloys, and of cadmium exchange in clay minerals and zeolites. The chemical shifts of Cd compounds are normally reported with respect to aqueous Cd(C104)2 solution. 

Table 3. Vertical ionization energies / (in eV) of gaseous zinc(II), cadmium(II) and mercury (II) compounds. The lowest / corresponds to a M.O. with symmetry type (and oj = 3/2 in spin-orbit coupling) mainly consisting of halide n pn orbitals (carbon a in the case of dimethylmercury). Further on, the d-like components at high / are given in two groups (separated by a semi-colon) with 2Ds/2 at lower and 2D3/2 at higher /.

Spin-lattice relaxation rates for cadmium in organometallic compounds have been measured for neat dibutylcadmium (13) (T 0.2 sec - 5 sec Temp = 228 K Bq = 2.1 Tesla) and dimethyl-, diethyl-, and dipropylcadmiura (15) (T = 3.5-0.6 sec Bq = 2.35 Tesla). From NOE measurement, neat dimethylcadmium experiences no dipolar relaxation (15). Mechanisms contributing to relaxation are thought to be chemical exchange and chemical shielding anisotropy however, their relative importance has not been published for these compounds. 

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