PURE NUCLEAR QUADRUPOLE RESONANCE SPECTRUM OF COBALT-59 IN ADDUCTS OF COBALT TETRACARBONYL MX3CO(CO)4

The 59Co pure nuclear quadrupole resonance spectra of a series of trigonally coordinated cobalt complexes, MX3Co(CO)4, where M = Si, Ge, Sn, and Pb and X = Cl, Br, I, and C6H5, are reported. The 35,37Cl quadrupole resonances in SiCl3Co(CO)4 are also reported. The variation in field gradients obtained from the quadrupole coupling constants in these molecules can be interpreted in terms of σ and π bonding of MX3 to the cobalt. In certain cases explicit σ or π effects can be separated. Finally, strong evidence for the existence of Si-Cl dπ-pπ bonding is presented. © 1969, American Chemical Society. All rights reserved.