CD-113 SHIELDING TENSORS OF MONOMERIC CADMIUM COMPOUNDS CONTAINING NITROGEN DONOR ATOMS .3. CP MAS STUDIES ON 5-COORDINATE CADMIUM COMPLEXES HAVING N(3)X(2) (X=H,N,O, AND S) DONOR ATOMS/

The principal elements of the Cd-113 shielding tensor for a set of fiv e- coordinate compounds having mixed donor atoms coordinating to the c admium were determined via CP/MAS NMR experiments. The first complex, [HB(3,5-Me(2)pz)(3)]CdBH4 (where pz = pyrazolyl), has a CdN3H2 inner c oordination sphere. The isotropic chemical shift in the solid state is 355.1 ppm, and its chemical shift anisotropy (CSA, Delta sigma) is -5 96,ppm with an asymmetry parameter (eta) of 0.64. The second complex, [HB(3,5-Me(2)pz)(3)]Cd[H2B(pz)(2)], has five nitrogen donor atoms bond ed to the cadmium. This N-5 or N3N2 compound was the only material of this study to manifest dipolar splitting of the cadmium resonance from the quadrupolar(14)N. Th, isotropic chemical shift, CSA, and the valu e of eta for this material were therefore determined at higher field w here the dipolar splitting was less than the linewidth, yielding value s of 226.6 ppm, -247 ppm, and 0.32, respectively. A second N-5 materia l, [HB(3-Phpz)(3)]Cd[H2B(3,5-Me(2)-pz)(2)], was also investigated and has an isotropic shift of 190.2 ppm, a CSA of 254 ppm, and an eta of 0 .86. Also studied was [HB(3-Phpz)(3)]Cd[(Bu(t)CO)(2)CH], which has an CdN3O2 inner core. The isotropic chemical shift of this complex is 173 .6 ppm, and the values of Delta sigma and eta were determined to be -2 58 ppm and 0.38, respectively. The final compound, [HB(3,5-Me(2)pz)(3) ]Cd[S(2)CNEt(2)], with N3S2 donor atoms, has an isotropic shift of 275 .8 ppm, an eta of 0.51, and a CSA of +375 ppm. Utilizing previous assi gnments, the most shielded tensor element was determined to be oriente d normal to the plane of the tridentate ligand. The shielding tensor i nformation is used to speculate on the Coordination geometry of the Cd N3O2 inner core complex.