~(155)Gd Moessbauer Isomer Shifts and Quadrupole Coupling Constants of Gadolinium Complexes

摘要

We have examined the ~(155)Gd Moessbauer spectra at 12 K for 25 complexes having different coordination numbers and different ratios of coordinating oxygen to nitrogen atoms. The isomer shift decreases in the order: GdO_(10) ≈ GdO_9 > GdN_2O_7 ≥ GdO_8 ≈ GdN_6O_2 ≥ GdO_7 ≥ GdO_6 > GdN_8 ≈ GdN_9. The s electron density at the nucleus is larger as the coordination number decreases and as the coordinating atoms change from oxygen to nitrogen, suggesting the covalency in the bonding.