Spin polarization and ferromagnetic coupling in metallocenium charge transfer complexes

Kollmar, Christian; Kahn, Olivier
February 1992
Journal of Chemical Physics;2/15/1992, Vol. 96 Issue 4, p2988
Academic Journal
Spin polarization effects in metallocenium complexes across the transition metal series Cr, Mn, Fe, Co, Ni are discussed in a qualitative fashion using a restricted open-shell Hartree–Fock approach. The spin polarization is taken into account by a limited configuration interaction (CI) with singly excited configurations. In Fe(C5Me5)+2, Mn(C5Me5)+2, and Cr(C5Me5)+2, the unpaired electrons are localized in molecular orbitals with predominant metal 3d character. The polarization of the metal–cyclopentadiene π bonds then leads to a negative spin density on the cyclopentadiene (Cp) rings. The amount of negative spin density on Cp increases with increasing spin on the metal (S=1/2, S=1, and S=3/2 for ferrocenium, manganocenium, and chromocenium, respectively). The Cp spin density of nickelocenium on the other hand is positive because there is a direct delocalization of spin density to the Cp rings due to the considerable Cp contributions to the e[ATOTHER]@B|[/ATOTHER] 1g molecular orbitals in which the unpaired electron of nickelocenium is located. Correspondingly, the charge transfer complexes of these compounds with the acceptors tetracyanoethylene (TCNE) or tetracyanoquinodimethane (TCNQ) in an alternating arrangement ...D+A-D+A-... are expected to exhibit ferromagnetic donor–acceptor coupling for Fe(C5Me5)+2, Mn(C5Me5)+2, and Cr(C5Me5)+2 and antiferromagnetic coupling for Ni(C5Me5)+2 according to a model suggested previously by the authors and based on an idea of McConnell. This is in agreement with the experimental results. The observed nuclear magnetic resonance (NMR) shifts of some metallocenes in relation to these findings are discussed.


Related Articles

  • Formation of Polymer Complexes of Transition Metals with Fullerene. Popov, A. P.; Bazhin, I. V. // Physics of the Solid State;Mar2002, Vol. 44 Issue 3, p567 

    This paper reports on the results of ab initio unrestricted Hartree-Fock (UHF) calculations of the equilibrium geometry and binding energy for the transition-metal complexes Me(C[sub 5]H[sub 5])[sub 2] and Me(C[sub 6]H[sub 6])[sub 2] and the energetically stable metallofullerene complexes...

  • Transition metal complexes with open d-shell in semiempirical context. Application to analysis of Mössbauer data on spin—active iron(II) compounds. Darkhovskii, M.B.; Soudackov, A.V.; Tchougréeff, A.L. // Theoretical Chemistry Accounts: Theory, Computation, & Modeling;Sep2005, Vol. 114 Issue 1-3, p97 

    With use of cumulants of two-electron density matrices semiempirical methods are analyzed from a point of view of their suitability to describe qualitative features of electronic correlation important for calculation of electronic structure of the transition metal complexes (TMC). It is shown...

  • The ab initio model potential method. First series transition metal elements. Seijo, Luis; Barandiarán, Zoila; Huzinaga, Sigeru // Journal of Chemical Physics;12/1/1989, Vol. 91 Issue 11, p7011 

    In the ab initio core model potential method the Coulomb and exchange core operators are represented accurately and the valence basis set is the only component of the method which is optimized (following the variational principle) in an atomic valence restricted Hartree–Fock (RHF)...

  • The role of range-separated Hartree-Fock exchange in the calculation of magnetic exchange couplings in transition metal complexes. Phillips, Jordan J.; Peralta, Juan E. // Journal of Chemical Physics;1/21/2011, Vol. 134 Issue 3, p034108 

    We assess the dependence of magnetic exchange couplings on the variation of Hartree-Fock exchange (HFX) admixture in global hybrid functionals and the range-separation parameter ω in range-separated hybrid functionals in a set of 12 spin-1/2 binuclear transition metal complexes. The global...

  • A new internally contracted multi-reference configuration interaction method. Shamasundar, K. R.; Knizia, Gerald; Werner, Hans-Joachim // Journal of Chemical Physics;8/7/2011, Vol. 135 Issue 5, p054101 

    We present a new internally contracted multi-reference configuration interaction (MRCI) method which, at the same time, efficiently handles large active orbital spaces, long configuration expansions, and many closed-shell orbitals in the reference function. This is achieved by treating the...

  • Towards quantifying the role of exact exchange in predictions of transition metal complex properties. Ioannidis, Efthymios I.; Kulik, Heather J. // Journal of Chemical Physics;2015, Vol. 143 Issue 3, p1 

    We estimate the prediction sensitivity with respect to Hartree-Fock exchange in approximate density functionals for representative Fe(II) and Fe(III) octahedral complexes. Based on the observation that the range of parameters spanned by the most widely employed functionals is relatively narrow,...

  • Polarization consistent basis sets: Principles. Jensen, Frank // Journal of Chemical Physics;11/22/2001, Vol. 115 Issue 20, p9113 

    The basis set convergence of Hartree–Fock energies for the H[sub 2], H[sub 3][sup +], C[sub 2], N[sub 2], N[sub 4], O[sub 2], O[sub 3], F[sub 2], HF, and CH[sub 4] molecules is analyzed using optimized basis functions. Based on these analysis a sequence of polarization consistent basis...

  • Analytical time-dependent Hartree–Fock schemes for the evaluation of the hyper-Raman intensities. Quinet, Olivier; Champagne, Benoı⁁t // Journal of Chemical Physics;8/8/2002, Vol. 117 Issue 6, p2481 

    Two analytical procedures based on the time-dependent Hartree-Fock (TDHF) scheme are elaborated to evaluate the first derivatives of the dynamic first hyperpolarizability with respect to atomic Cartesian coordinates. In the first scheme, the mixed third-order TDHF equations are solved...

  • New Slater-type orbital basis sets for first row transition elements. Bernardo, L. A. G.; Sordo, J. A. // Journal of Chemical Physics;8/1/1986, Vol. 85 Issue 3, p1475 

    A comparative study, at the atomic level, of the quality of eight Slater-type orbitals (STO) basis sets has been carried out for the first row transition elements. Two new basis sets are proposed for these elements: the β1 basis set (small-size-type) and the α2 basis set...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics