Dynamic Behavior of the Jahn−Teller Distorted Cu(H₂O)₆²⁺ Ion in Cu²⁺ Doped Cs₂[Zn(H₂O)₆](ZrF₆)₂ and the Crystal Structure of the Host Lattice

Abstract

The temperature dependence of the X- and Q-band EPR spectra of Cs(2)[Zn(H(2)O)(6)](ZrF(6))(2) containing approximately 1% Cu(2+) is reported. All three molecular g-values vary with temperature, and their behavior is interpreted using a model in which the potential surface of the Jahn-Teller distorted Cu(H(2)O)(6)(2+) ion is perturbed by an orthorhombic "strain" induced by interactions with the surrounding lattice. The strain parameters are significantly smaller than those reported previously for the Cu(H(2)O)(6)(2+) ion in similar lattices. The temperature dependence of the two higher g-values suggests that in the present compound the lattice interactions change slightly with temperature. The crystal structure of the Cs(2)[Zn(H(2)O)(6)](ZrF(6))(2) host is reported, and the geometry of the Zn(H(2)O)(6)(2+) ion is correlated with lattice strain parameters derived from the EPR spectrum of the guest Cu(2+) complex.

Theoretical studies of the g factors and local structures of the Ni3+ centers in Na2Zn(SO4)2·4H2O and K2Zn(SO4)2·6H2O crystals

“…The studied Ni 3+ centers in DPPH and PHZS crystals are different from other TM impurity (e.g., Mn 2+ , Cr 3+ , and Fe 3+ [46][47][48] ) centers in the same crystals, with the nondegenerated ground state in the absence of the Jahn-Teller effect. In addition, when the impurity Cu 2+ enters Tutton salts, [14,15,[49][50][51][52] it may also occupy the host Zn 2+ site, but usually presents elongated octahedra instead of the compressed octahedra in the studied systems.…”

Dipotassium hexaaquanickel(II) bis[hexafluoridozirconate(IV)]

“…(2011). E67, i6-i7 9Zr-F3 = 1.968 5Zr-F3 = 1.9727 3Zr-F3 = 1.962 (5) Zr-F5 = 2.0006 8Zr-F1 = 2.004 (5) Zr-F1 = 2.0018 3Zr-F6 = 1.977 (5) Zr-F3 = 2.0293 9Zr-F5 = 2.029 (4) Zr-F5 = 2.0277 (3) Zr-F5 = 2.037 (5) Distances Zr-F (Å ) Zr-F2 = 2.0554 (8) Zr-F6 = 2.059 (4) Zr-F6 = 2.0570 (3) Zr-F4 = 2.067 (4) Zr-F1 = 2.0708 8Zr-F2 = 2.063 (4) Zr-F2 = 2.0668 (4) Zr-F2 = 2.069 (4) Zr-F4 = 2.1468 9Zr-F4 = 2.156 5 2Cs-F3 = 3.065 (5) K-F1 = 2.7895 9K-F2 = 2.799 (5) K-F3 = 2.8094 2Cs-F3 = 3.102 (5) K-O2 = 2.8927 10K-O3 = 2.942 (5) K-O1 = 2.8968 3Cs-O2 = 3.218 (5) K-O1 = 3.1012 10K-O1 = 2.980 (5) K-O2 = 3.0873 5Cs-O1 = 3.236 (5) K-F6 = 3.1684 12K-F3 = 3.1307 7K-F3 = 3.1707 7Cs-F5 = 3.228 6 Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999) and ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 (Bukvetskii et al, 1993) (Hitchman et al, 2002). In the title structure the Ni 2+ cation (site symmetry 1) is coordinated by six water molecules with two Ni-O distances slightly longer (2.0781 (9) Å) than the four others (2x 2.0548 (10) Å and 2x 2.0570 (11) Å).…”

Electron Paramagnetic Resonance Characteristics and Crystal Structure of a Tutton Salt Analogue: Copper-Doped Cadmium Creatininium Sulfate

“…Several of these EPR studies revealed limitations of the SG model, the most apparent being that 12 is not constant over the entire temperature range 2,4,9,[12][13][14][15] . In other systems, the tensor variations that were not fully predicted, 4,11,18 which was initially suggested as due to a non-Boltzmann thermal equilibrium at low temperatures, but later also from temperature dependent changes in the lattice strains. In a few other cases, gmin was observed to vary with temperature 4,9 and therefore a three-state SG model was applied 1,9,10 .…”

“…The inclusion of lattice strain parameters generally led to better agreements to the g-tensor variations, but also found good comparisons with the 12 values that were estimated from the SG model 3,15,19 . However, three systems; the Magnesium Ammonium Tutton salt (abbreviated MgNH4S) 4 , the Zinc Ammonium Tutton salt (abbreviated ZnNH4S) 11 and the Tutton analog, Cs2Zn(H2O)6(ZrF6)2 18 exhibited behaviors inconsistent with either the SG or vibronic models. These failures were attributed to host dynamics of the NH4 groups and/or fluxations in the hydrogen bonding interactions, leading to temperature dependent deformations of the potential energy surfaces 11,18,21 .…”

“…However, three systems; the Magnesium Ammonium Tutton salt (abbreviated MgNH4S) 4 , the Zinc Ammonium Tutton salt (abbreviated ZnNH4S) 11 and the Tutton analog, Cs2Zn(H2O)6(ZrF6)2 18 exhibited behaviors inconsistent with either the SG or vibronic models. These failures were attributed to host dynamics of the NH4 groups and/or fluxations in the hydrogen bonding interactions, leading to temperature dependent deformations of the potential energy surfaces 11,18,21 . Keeping in mind the restricted temperature validity of the SG model in most of these systems, the 12 values used in discussions below were those reported in ranges where they remained relatively constant, i.e., usually when T>120 K.…”