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Relaxation studies of carbonyl rhenium clusters. Part 2 —relaxation mechanisms and estimation of the 13 C chemical shielding anisotropy in the [Re 3 (μ‐H) 4 (CO) 10 ] − anion at low temperature
Author(s) -
Beringhelli Tiziana,
D'Alfonso Giuseppe,
Molinari Henriette
Publication year - 1986
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260240215
Subject(s) - chemistry , anisotropy , rhenium , relaxation (psychology) , electromagnetic shielding , ion , spin–lattice relaxation , atmospheric temperature range , isotropy , spectral line , nuclear magnetic resonance , analytical chemistry (journal) , molecular physics , condensed matter physics , inorganic chemistry , paramagnetism , social psychology , psychology , physics , organic chemistry , quantum mechanics , astronomy , chromatography , meteorology , electrical engineering , engineering
Application of the non‐selective inversion recovery technique to 13 C spectra of moderately enriched [Re 3 (μ‐H) 4 (CO) 10 ] − indicates that relaxation times, at low temperatures, are strongly field dependent and decrease with increasing field strength. Measurements performed at 183 K and at 20.15, 50.31 and 67.88 MHz indicate that chemical shielding anisotropy is dominant at higher fields, which differs from the behaviour previously observed at room temperature where the main relaxation pathway is scalar coupling with the quadrupolar rhenium isotopes. The 13 C chemical shielding anisotropy was estimated to be in the range 476±40 ppm. Interactions with quadrupolar rhenium also affect the hydrogen spin‐spin relaxation times.