Paul Goddard

Abstract:

Solid state techniques involving pressure and temperature have been used to synthesize the fluoride member of the CuX2(pyrazine) (X = F, Cl, Br) family of coordination polymers that cannot be crystallized by solution methods. CuF2(pyrazine) exhibits unique trans doubly-bridged Cu-F2-Cu chains that provide an opportunity to quantify magnetic superexchange in an isostructural Cu-X2-Cu series. © 2013 The Royal Society of Chemistry.

Abstract:

CuF(2)(H(2)O)(2)(3-chloropyridine) possesses a five-coordinate Cu(2+) center with a slightly distorted trigonal bypyramidal coordination geometry. Strong intermolecular F···H-O hydrogen bonds enable the formation of 2D layers and provide the primary magnetic exchange path that leads to the stabilization of long-range antiferromagnetic (AFM) order below T(N) = 2.1 K.

Abstract:

Figure Persented: [Ni(HF 2)(3-Clpy) 4]BF 4 (py = pyridine) is a simple one-dimensional (1D) coordination polymer composed of compressed NiN 4F 2 octahedra that form chains with bridging HF 2- ligands. In spite of significant distortion of the HF 2- bridge, a quasi-1D antiferromagnetic (AFM) behavior was observed with J FHF = 4.86 K. © 2012 American Chemical Society.

Abstract:

[Ni(HF(2))(3-Clpy)(4)]BF(4) (py = pyridine) is a simple one-dimensional (1D) coordination polymer composed of compressed NiN(4)F(2) octahedra that form chains with bridging HF(2)(-) ligands. In spite of significant distortion of the HF(2)(-) bridge, a quasi-1D antiferromagnetic (AFM) behavior was observed with J(FHF) = 4.86 K.

Abstract:

A tetragonal polymorph of [Ni(HF(2))(pyz)(2)]PF(6) (designated β) is isomorphic to its SbF(6)-congener at 295 K and features linear Ni-FHF-Ni pillars. Enhancements in the spin exchange (J(FHF) = 7.7 K), Néel temperature (T(N) = 7 K), and critical field (B(c) = 24 T) were found relative to monoclinic α-PF(6). DFT reveals that the HF(2)(-) bridges are significantly better mediators of magnetic exchange than pyz (J(pyz)), where J(FHF) ≈ 3J(pyz), thus leading to quasi-1D behavior. Spin density resides on all atoms of the HF(2)(-) bridge whereas N-donor atoms of the pyz ring bear most of the density.