PREPARATION AND PROPERTIES OF (ETA-C5H5)2TICL(SEH), (ETA-C5H5)2TI(SEH)2, [(ETA-C5H5)TI]4(MU-2-SE)3(MU-3-SE)3, AND RELATED CYCLOPENTADIENYL SELENIDES OF TITANIUM

The reaction between (eta-C5H5)2TiCl2 and H2Se in tetrahydrofuran as solvent and in the presence of (C2H5)3N gave [(eta-C5H5)Ti]4(mu-2-Se)3(mu-3-Se)3. The structure of the product was determined by X-ray diffraction (crystal data for (C5H5)4Ti4Se6.(C2H5)3N: P1BAR; a = 10.971 (1), b = 11.148 (2), c = 13.943 (1) angstrom; alpha = 88.38 (1), beta = 78.29 (7), gamma = 81.17 (1)-degrees; Z = 2; R = 0.070 for 335 variables and 2961 observed reflections). The cluster has one six-coordinate Ti atom linked to three mu-3-Se's (average Ti-Se = 2.389 (3) angstrom) and three seven-coordinate Ti atoms linked to three mu-3-Se's (average Ti-Se = 2.700 (3) angstrom) and to three mu-2-Se's (average Ti-Se = 2.508 (3) angstrom). The cluster is diamagnetic, since it contains four Ti(IV) centers. The reaction between (eta-C5H5)2TiCl2 and H2Se in tetrahydrofuran and in the presence of pyridine gave a mixture of (eta-C5H5)2TiCl(SeH) and (eta-C5H5)Ti(SeH)2. When the reaction was conducted in the presence of O2, the product was [(eta-C5H5)2TiCl]2(mu-Se2). The reactions are compared to those between (eta-C5H5)2Ti(CO)2 and H2Se.