Multi-centre contributions to the anisotropic hyperfine interactions in the cu(ii) bis(dithiocarbamate) complex. Proton hyperfine couplings

Keijzers, C. P.; Snaathorst, D.

doi:10.1016/0009-2614(80)85078-0

Cited by 35 publications

(5 citation statements)

References 14 publications

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“…At large distances this term can be presented by a point-dipole approximation. , The “bond” contribution arises from the unpaired spin density in the bonds surrounding atom N i . Finally, the three-center terms arise from the spin density in remote bonds and are given by A similar partitioning has been carried out before by Keijzers and Snaathorst and the individual terms were evaluated with STO-6G fits to extended Hückel orbitals for [Cu(dtc) 2 ] 15d. In this section A nonloc , , , and A orb are assumed to be small corrections that will be neglected.…”

Section: Theorymentioning

confidence: 99%

“…However, much fewer computations have been reported for the interpretation of ligand SHFCs in transition metal complexes. Detailed early work is due to Keijzers and co-workers who correlated high precision experimental data on [Cu(dtc) 2 ] with extended Hückel calculations. , Geurts et al studied the same system using the Hartree−Fock Slater (HFS) method. They evaluated metal- and ligand-SHFC tensors as well as the g -tensor using uncoupled Kohn−Sham (KS) perturbation theory and found good agreement between theory and experiment .…”

Section: Introductionmentioning

confidence: 99%

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Theoretical Study of Ligand Superhyperfine Structure. Application to Cu(II) Complexes

2001

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A theoretical and computational study of the nitrogen superhyperfine structure in Cu(II) complexes is reported. The determination of hybridization parameters for nitrogen donor orbitals from the data is examined. For most Cu(II) complexes the results deviate substantially from pure “sp2” or “sp3” hybridization. Semiempirical INDO/S calculations for five Cu(II) complexes were carried out at the UHF and ROHF level. The results suggest that the small anisotropy in the nitrogen hyperfine parameters is caused by spin polarization of the nitrogen valence shell orbitals. A simple, approximate way for the determination of the π-spin density from experimental data is outlined. A density functional study using various basis sets and functionals is reported for the same five complexes. Hybrid functionals, such as B3LYP and PWP1, give better predictions than functionals based on the generalized gradient approximation like BP or BLYP. Provided that at least a polarized triple-ζ basis is used, the hybrid functionals B3LYP and PWP1 give good predictions for the isotropic couplings but overestimate the anisotropic part by almost a factor of 2. The computational results are further analyzed in terms of local versus nonlocal contributions, influence of scalar relativistic and spin−orbit coupling effects and the transferability of quasi-atomic hyperfine couplings.

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Section: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Theoretical Study of Ligand Superhyperfine Structure. Application to Cu(II) Complexes

2001

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“…In (11), Xk~ represents the Kth atomic orbital centred at the nucleus k. Keijzers and Snaathorst [19] have shown that, in general, these multieentre contributions cannot be neglected. For centres with high spin density (metal), however, the one centre terms dominate the remaining integrals.…”

Section: Hze~ = It +Ges~mentioning

confidence: 99%

“…This restriction may be dropped by using spin polarized wave functions [36] of the type r = det {r t~,.. Cno~r162 (19) The spin density at a point R is then given by…”

Section: Carbon-13 Hyperfine Tensorsmentioning

confidence: 99%

On the electronic structure ofN,N′-ethylenebis-(acetylacetonatiminato)Co(II), Co(II)acacen III. Comparison of ENDOR results with semiempirical calculations

1982

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The magnetic parameters (electron g-, hyperfine and quadrupole tensors) of Co(acacen) in Ni(acacen) . 89 which have been derived from a single crystal E.P.R./ENDOR study, are interpreted using the results of model calculations at EHMO, INDO and X~ level. A theory for the calculation of the magnetic parameters from the MO data for low symmetry systems with low-lying excited states is given. Within this framework, the noncoaxiality of the g-, cobalt hyperfine and quadrupole tensors is explained. The hyperfine tensors of the ligand nuclei are described qualitatively by the MO calculations, a quantitative explanation, however, is not possible. This is, among other reasons, due to the neglect of polarization effects (EHMO, X~) and of spin-orbit coupling contributions (INDO, X~). Their importance is illustrated by the negative spin densities found in carbon 2pz orbitals and by the large deviation of the g principal values from the free electron ge, respectively. Problems like asymmetric hyperfine tensors for low symmetry systems and the derivation of structural information from ENDOR results are briefly commented on. The nitrogen quadrupole tensors are interpreted in terms of the Townes-Dailey theory.

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“…The assignment to the correct protons and the analysis of another five tensors was possible only by elaborate computer calculations as described earlier. 25 In this method, the coefficients of the molecular orbital of the unpaired electron (as obtained from the EHMO calculation) are used to calculate the hyperfine coupling tensors, including the two-and three-centre contributions. From these theoretical tensors, the predicted ENDOR frequencies are calculated and compared with the experimental frequencies.…”

Section: Endor S P E C M -mentioning

confidence: 99%

Proton ENDOR spectroscopy of bis(2,2,6,6-tetramethylheptane-3,5-dionato)copper(II) and crystal structure of bis(2,2,6,6-tetramethylheptane-3,5-dionato)palladium(II)

Baker¹,

Raynor²,

Smits³

et al. 1986

J. Chem. Soc., Dalton Trans.

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The proton electron nuclear double resonance spectroscopy of a single crystal of bis( 2,2,6,6tetramethylheptane-3,5-dionato)copper( 11) in the palladium analogue has been studied. Tensors could be determined for the y-proton and t w o nearest But protons as well as six protons on the nearest-neighbour palladium complex. The assignment of most of these was enabled by the comparison with theoretically calculated tensors. This calculation procedure has been described previously: it uses the molecular orbital coefficients as obtained from an extended Huckel calculation and includes all t w o -and three-centre contributions. The remaining experimental curves could not be fitted t o calculated tensors. The structure of the palladium analogue, C, H, O, Pd, was determined by X-ray crystallography at 140 K: monoclinic, space group P2,/n, a = 1 1.245(3), b = 12.008(8), c = 9.851 (3) A, p = 11 0.1 7(3)", and Z = 2 (Mo-K, radiation, graphite crystal monochromator). Final conventional R = 0.029, R' = 0.044 for 1 654 unique reflections and 186 variables.

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Multi-centre contributions to the anisotropic hyperfine interactions in the cu(ii) bis(dithiocarbamate) complex. Proton hyperfine couplings

Cited by 35 publications

References 14 publications

Theoretical Study of Ligand Superhyperfine Structure. Application to Cu(II) Complexes

Theoretical Study of Ligand Superhyperfine Structure. Application to Cu(II) Complexes

On the electronic structure ofN,N′-ethylenebis-(acetylacetonatiminato)Co(II), Co(II)acacen III. Comparison of ENDOR results with semiempirical calculations

Proton ENDOR spectroscopy of bis(2,2,6,6-tetramethylheptane-3,5-dionato)copper(II) and crystal structure of bis(2,2,6,6-tetramethylheptane-3,5-dionato)palladium(II)

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