Electron paramagnetic resonance on transition metal complexes

摘要: The EPR signal of Cp2TiIIIH2AlCl2 in tetrahydrofuran shows an alternating line-width effect involving the MI = ±1 and 0 spin states two bridge hydrogens, indicating existence a dynamic molecular process which involved coupling constant undergoes out-of-phase modulation. Evaluation temperature dependence leads to activation energy 4 kcal/mol, implies that complete breaking chemical bond is not involved. It proposed one hydrogen more tightly bonded Al, other Ti, motion concerns flopping reverse conformation. When di-π-cyclopentadienyltitanium dichloride (Cp2TiCl2) reduced with metallic sodium presence freshly sublimed AlCl3, paramagnetic species formed after several hours stirring at room temperature. reaction solution gives strong electron resonance signal. Double integration first derivative spectrum indicates some 60% initial amount titanium ([Ti] 10 x 10−3 mol/1) present signal-producing form. essential feature interaction unpaired TiIII nucleus Al (I 52), giving rise six equivalent hyperfine lines. On extreme dilution further structure resolved (Fig. 1). Each lines split into 1/2/1 triplet by nuclei, furthermore splitting each component uneven number very narrow