J. Am. Chem. Soc., 129 (21), 6704 -6705, 2007.
Ultrahigh-Field Solid-State 59Co NMR Studies of Co(C2B9H11)2- and Co(C5H5)2+ Salts
Kristopher J. Ooms, Victor V. Terskikh, and Roderick E. Wasylishen*
Cobalt-59 NMR spectra of stationary powder samples of salts containing Co(C2B9H11)2- and Co(C5H5)2+ have been acquired at 21.14 T using single-echo stepped-frequency experiments. The resulting central transition, mI = 1/2 mI = -1/2, line shapes span more than 2.0 MHz and are dominated by the second-order quadrupolar interaction. Analysis of the spectra leads to CQ values of ca. 163 MHz for both ions, among the largest 59Co CQ values reported. In addition, 59Co chemical shift anisotropies are significant for Co(C2B9H11)2- and Co(C5H5)2+, with values of 4500-4700 and 5650 ppm, respectively. Isotropic 59Co chemical shifts for the cobalticarborane anion are unavailable from NMR measurements of solution samples, probably because of the extremely short relaxation times anticipated for this complex.