Some aspects of metal-olefin bonding in cyclopentadienylcobalt-cyclic olefin complexes as evidenced by cobalt-59 nuclear quadrupole resonance

59Co second-order quadrupolar effects in the13C cross-polarization magic angle spinning NMR spectra of the cobaltocenium salts [Cp*2Co]+[PF6]− and [Cp*CpCo]+[PF6]−

“…17 In our case the axially symmetric EFG tensor ⊲ D 0⊳ should be aligned along the fivefold symmetry axis ⊲˛D 0⊳. 18 The isotropic chemical shift υ ISO was determined from the high-field spectrum (where the second-order quadrupolar effects are lessened), and the 59 Co Larmor frequencies ⊲ 59 Co⊳ were obtained after multiplying the ⊲ 13 C⊳ values in Table 1 by 0.94. Scalar coupling constants J⊲ 59 Co, 13 C) or J do not seem to be available for cobaltocenium cations.…”

Ultrahigh-Field Solid-State 59Co NMR Studies of Co(C2B9H11)2- and Co(C5H5)2+ Salts

“…The synthesis and characterization of these compounds have become a fascinating area of research, and many applications of the dicarbollide anion have been discovered, including a recent report that Co(1,2-C 2 B 9 H 11 ) 2 - and its derivatives act as an inhibitor for HIV protease. − The Co(1,2-C 2 B 9 H 11 ) 2 - complex can also adopt different conformations; for example, the relative orientation of the two carboranes can be rotated and are typically either cis, Figure , or trans to each other; the Et 3 NH + and Rb + salts adopt the cis conformation. , There are few NMR studies because the sandwich complexes result in large EFGs at the cobalt. NQR studies have shown that C Q values range from 138 to 171 MHz, some of the largest reported for 59 Co. In solution, large C Q values result in relaxation times on the order of microseconds, and consequently, large 59 Co NMR line widths.…”