MAGNETISM, SPECTROSCOPY AND STRUCTURE OF ETHYL-1,1,1-TRIS(AMINOMETHYL)ETHANE]CHROMIUM(III)) CHLORIDE TETRAHYDRATE

A new trihydroxo bridged chromium cation [(Me3-tame)Cr(OH)3Cr(Me3-tame )]3+, where Me3-tame is [N,N',N''-trimethyl-1,1,1-trisaminomethyl)etha ne], has been isolated as several salts. The structure of the cation i solated as a chloride tetrahydrate was determined from low-temperature X-ray data. This compound crystallizes in the monoclinic space group P2(1)/n with a = 9.674(3), b = 13.775(3), c = 22.947(4) angstrom, beta = 102.50(2)-degrees and Z = 4. Using 16 027 observed reflections the structure was refined to R = 0.034 and R(w) = 0.047. The symmetry of t he cation in the cloride salt is close to C3h with a Cr-Cr distance of 2.6359(3) angstrom. The temperature-dependent magnetic susceptibility showed that the two chromium ions in the dimeric unit are antiferroma gnetically coupled with a triplet-singlet seperation of 147 cm-1. X-B and EPR spectra of a crystalline powder of the chloride salt showed li nes which could be interpreted as transitions within the quintet and t riplet state. Good estimates of the monomeric spin Hamiltonian paramet ers could be obtained by recording EPR spectra of the analogous Co-Co triol (or Cr-Cr triol) contamined with 1% of the Cr-Co triol. The EPR spectra were simulated with the parameters D1 = D2 = 0.80 cm-1, E1 = E 2 -0.0085 cm-1, D(e) = 0.01 94 cm-1 and E(c) = 0.0049 cm-1.