The Ground State in Tris(acetylacetonato)ruthenium(III) from Low-Temperature Single-Crystal Magnetic Properties

The magnetic susceptibilities of tris(acetylacetonato)ruthenium(III) have been measured between 2·5 and 300 K along the a, b, c, and a* axis directions, together with the magnetizations along the same directions up to a magnetic field of 5 T. There is a small amount of magnetic exchange interaction apparent below 10 K, with Weiss constants up to –0·35 K and the magnetization is fitted with exchange integrals up to –0·38 K in magnitude. A pathway for magnetic exchange in terms of a pair of symmetry-related Ru(acac) rings lying parallel and close is obvious from the structure. The susceptibility results above 10 K have been interpreted in terms of a four-parameter ligand field model (CF1) operating on the ground 2T2g term of the d5 configuration. The t2g orbitals are found to be split by 475 cm-1 by a dominant trigonal symmetry component and then by –50 cm-1 by a subsidiary rhombic component. The single-electron spin-orbit coupling constant is 875 cm-1 and the orbital angular momentum reduction parameter is 0·7. The g-values deduced for the ground Kramers doublet are not in good agreement with those from e.s.r. experiments, but rather better agreement is found for closely allied ligand field parameter sets (CF2) which can fit the susceptibilities at particular temperatures but do not reproduce their temperature dependence well. Consideration of the variation of structural details with temperature indicate that, in fact, the CF2 sets may be more realistic.

Fluorosulfates of palladium

The syntheses of Pd(SO3F)2 and Pd(SO3F)3 by the reactions of palladium with BrOSO2F and S2O6F2 are described. Structural information on both compounds is based on infrared, Raman, diffuse reflectance, and electronic mull spectra as well as magnetic measurements from ∼300 to ∼100 K. Palladium bisfluorosulfate is found to have a polymeric structure with the fluorosulfate group acting as a tridentate ligand. As a consequence, an octahedral environment is found for Pd2+ with a 3A2g ground state, a µeff298 value of 3.39 BM and the ligand field parameter Dq = 1177 cm−1 and B = 633 cm−1. Pd(SO3F)3 is best regarded as PdII[PdIV(SO3F)6].

NOTIZEN: EPR- und ligandenfeld-spektroskopische Strukturuntersuchungen an Cu(II)-Verbindungen / Investigations with Respect to the Structure of Cu(II)-compounds by EPR and Ligand Field Spectroscopy

From EPR and ligand field parameter some significant structural details of Cu(II)-compounds can be determined to a notable accuracy: a) the symmetry (tetragonal or orhombic) of Jahn-Teller distorted octahedral Cu(II)-sites, and b) the ordering of Jahn-Teller coupled Cu(II)-polyhedra with respect to each other as well as to the crystallographic axes of the Cu(II)-compound under investigation.

Magnetism, electronic spectra, and structure of transition metal alkoxides. I. methoxides and ethoxides of chromium(II), manganese(II), Iron(II), cobalt(II), nickel(II), copper(II), titanium(III), chromium(III), and iron(III)

The magnetic moments and electronic spectra are reported for the following divalent transition metal methoxides: Cr(OCH3)2, Mn(OCH3)2, Fe(OCH3)2, Co(OCH3)2, Ni(OCH3)2, and Cu(OCH3)2. These measurements when coupled with the involatility and insolubility of the compounds favour structures based on infinite lattices composed either of regular (Mn, Fe, Co, and Ni) or distorted (Cr and Cu) MO6 octahedra. The spectral data place the ligand field parameter, Δ, for the methoxide group very close to that of water.