2-DIMENSIONAL NUTATION CO-59 NMR OF SOLID CO4(CO)12

Co-59 2D nutation NMR experiments were conducted at 47.485 MHz in order to determine the quadrupole coupling constants (e2Qq/h) of Co-59 nuclei in solid Co4(CO)12. The 2D spectrum observed clearly indicates the presence of two inequivalent Co-59 nuclei, Co(apical) and Co(basal). The magnitude of e2Qq/h and the asymmetry parameter of the electric field gradient, eta, were determined to be 9 +/- 2 MHz and 0 for Co(basal), and 15 +/- 3 MHz and 0.8 for Co(apical). The large value of eta for Co(apical) suggests that the apical Co occupies the site on a pseudo-C3 axis in the crystalline lattice. These facts are consistent with our previous proposal that a symmetry conserved reorientation of the Co4-tetrahedron occurs in the solid state.