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EPR spectra in γ‐irradiated PPN + HFeW(CO) 9 − crystals
Author(s) -
Hynes Rosemary C.,
Springs Jerry J.,
Preston Keith F.,
Williams Antony J.
Publication year - 1991
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.1260290512
Subject(s) - chemistry , electron paramagnetic resonance , ion , unpaired electron , crystallography , spectral line , single crystal , crystal (programming language) , irradiation , crystal structure , impurity , molecule , nuclear magnetic resonance , physics , organic chemistry , astronomy , computer science , nuclear physics , programming language
Single crystals of PPN + HFeW(CO) 9 − prepared from THF · W(CO) 5 and PPN + HFe(CO) 4 − exhibit weak single‐line EPR spectra corresponding to the presence of two paramagnetic impurities. One of the spectra increases in intensity by an order of magnitude on 60 Co γ‐irradiation. The g 2 matrices for both species in an orthogonal crystal‐axis system were assembled from measurements of g values made at 77 K on crystallographically oriented samples. The intense spectrum has principal g values of 2.0064, 2.0468 and 2.1320 and principal directions of g which lie close to bonds emanating from the Fe nucleus of the undamaged anion. Consideration of the principal g values and directions for this species leads to an assignment to a FeW(CO) 9 − radical in which the unpaired electron is principally located in a Fe 3d z 2orbital directed along the FeH bond of the host anion. The other signal has principal g values (2.0229, 2.0425, 2.0950) close to those established for the singly bridged isomer of Fe 2 (CO) 8 − , but their directions do not correlate well with bond directions within the host anion. It is concluded that small amounts of the persistent Fe 2 (CO) 8 − radical generated in the preparative procedures substitute for the host anion in the crystals of PPN + HFeW(CO) 9 − .