title: Electron Spin Density on the N-Donor Atoms of Cu(II)-(Bis)oxamidato Complexes As Probed by a Pulse ELDOR Detected NMR.
abstract: We have applied the pulse ELDOR detected NMR (EDNMR) technique to determine the tensors of the transferred Cu (S = 1/2) - (14)N (I = 1) hyperfine (HF) interaction in single crystals of diamagnetically diluted mononuclear o-phenylenebis(N(R)-oxamide) complexes of [(n)Bu4N]2[Cu(opboR2)] (R = Et 1, (n)Pr 2) (1%) in a host lattice of [(n)Bu4N]2[Ni(opboR2)] (R = Et 3, (n)Pr 4) (99%) (1@3 and 2@4)). To facilitate the analysis of our EDNMR data and to analyze possible manifestations of the nuclear quadrupole interaction in the EDNMR spectra, we have treated a model electron-nuclear system of the coupled S = 1/2 and I = 1 spins using the spin density matrix formalism. It appears that this interaction yields a peculiar asymmetry of the EDMR spectra that manifests not only in the shift of the positions of the EDNMR lines that correspond to the forbidden EPR transitions, as expected, but also in the intensities of the EDNMR lines. The symmetric shape of the experimental spectra suggests the conclusion that, in the studied complexes, the quadrupole interaction is negligible. This has simplified the analysis of the spectra. The HF tensors of all four N donor atoms could be accurately determined. On the basis of the HF tensors, an estimate of the spin density transferred from the central paramagnetic Cu(II) ion to the N donor atoms reveals its unequal distribution. We discuss possible implications of our estimates for the magnetic exchange paths and interaction strengths in respective trinuclear complexes [Cu3(opboR2) (pmdta)2](NO3)2 (R = Et 6, (n)Pr 7).
authors.affiliation: Leibniz Institute for Solid State and Materials Research IFW Dresden , D-01171 Dresden, Germany.
authors.forename: Azar
authors.initials: A
authors.lastname: Aliabadi
authors.affiliation: Zavoisky Physical Technical Institute, Russian Academy of Sciences , 420029 Kazan, Russia.
authors.forename: Ruslan
authors.initials: R
authors.lastname: Zaripov
authors.affiliation: Zavoisky Physical Technical Institute, Russian Academy of Sciences , 420029 Kazan, Russia.
authors.forename: Kev
authors.initials: K
authors.lastname: Salikhov
authors.affiliation: Zavoisky Physical Technical Institute, Russian Academy of Sciences , 420029 Kazan, Russia.
authors.forename: Violeta
authors.initials: V
authors.lastname: Voronkova
authors.affiliation: Zavoisky Physical Technical Institute, Russian Academy of Sciences , 420029 Kazan, Russia.
authors.forename: Evgeniya
authors.initials: E
authors.lastname: Vavilova
authors.affiliation: Technische Universität Chemnitz , Fakultät für Naturwissenschaften, Strasse der Nationen 62, D-09111 Chemnitz, Germany.
authors.forename: Mohammad A
authors.initials: MA
authors.lastname: Abdulmalic
authors.affiliation: Technische Universität Chemnitz , Fakultät für Naturwissenschaften, Strasse der Nationen 62, D-09111 Chemnitz, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Rüffer
authors.affiliation: Leibniz Institute for Solid State and Materials Research IFW Dresden , D-01171 Dresden, Germany.|Institut für Festkörperphysik, Technische Universität Dresden , D-01062 Dresden, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Büchner
authors.affiliation: Leibniz Institute for Solid State and Materials Research IFW Dresden , D-01171 Dresden, Germany.|Zavoisky Physical Technical Institute, Russian Academy of Sciences , 420029 Kazan, Russia.
authors.forename: Vladislav
authors.initials: V
authors.lastname: Kataev