Accession Number : AD0655121

Title :   DIPOLE-DIPOLE INTERACTIONS OF A SPIN-1/2 NUCLEUS WITH A QUARDRUPOLE-COUPLED NUCLEUS.

Descriptive Note : Technical rept.,

Corporate Author : ILLINOIS UNIV URBANA DEPT OF CHEMISTRY AND CHEMICAL ENGINEERING

Personal Author(s) : Vanderhart,D. L. ; Gutowsky,H. S. ; Farrar,T. C.

Report Date : 20 JUN 1967

Pagination or Media Count : 9

Abstract : In recent nmr experiments, the dipolar broadening of the proton resonance in solid HMn(CO)5 and HCo(CO)4 has been used to estimate the metal-hydrogen bond distance. The M-H bond distances thus obtained are exceptionally short, 1.28 A for Mn-H and 1.42 A for Co-H. However, the analyses were based on the Van Vleck second moment expression which assumes that the nuclei are quantized in the direction (z) of the static magnetic field Ho and which therefore neglects any quadrupole coupling effects at the metal nucleus. This communication describes a theoretical analysis and numerical calculations for a two-spin (1/2, 7/2 system, having axial symmetry along the internuclear vector r and quadrupole coupling at the spin-7/2 nucleus. It is found that the second moment M2 of the spin-1/2 nucleus may be as much as 1.84 times its value in the absence of the quadrupole coupling. Therefore, the M-H bond distances reported previously may be as much as 12% too small. (Author)

Descriptors :   (*NUCLEAR SPINS, INTERACTIONS), (*HYDRIDES, *CHEMICAL BONDS), NUCLEI, DIPOLE MOMENTS, INTERACTIONS, NUCLEAR MAGNETIC RESONANCE, QUADRUPOLE MOMENT, ZEEMAN EFFECT, MOLECULAR SPECTROSCOPY, COBALT COMPOUNDS, MANGANESE COMPOUNDS, METAL CARBONYLS

Subject Categories : Atomic and Molecular Physics and Spectroscopy
      Nuclear Physics & Elementary Particle Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE