Chemistry of trivalent uranium metallocenes: electron-transfer reactions. Synthesis and characterization of [(MeC5H4)3U]2E (E = S, Se, Te) and the crystal structures of [(MeC5H4)3U]2S and (MeC5H4)3UOPPh3

The trivalent uranium metallocene (MeC5H4)3U x THF reacts with COS, SPPh3, or TeP(n-Bu)3 to form the bridging chalcogenide complexes [(MeC5H4)3U]2E, where E is S, Se, or Te. Crystals of [(MeC5H4)3U]2S are monoclinic, P21/c, with a = 19.740 (6) A, b = 8.302 (3) A, c = 21.602(4) A, and β = 97.28 (3)0 at 230C; for Z = 4 the calculated density is 1.920 g/cm3. The structure was refined by full-matrix least squares to a conventional R factor of 0.053 by using 2061 data with F2 > 2 sigma (F2). The average U-C distance is 2.77 +/- 0.06 A, the U-S distance is 2.60 (1) A, and the U-S-U angle is 164.9 (5)0. Triphenylphosphine oxide does not behave in a similar fashion; the trivalent uranium coordination complex (MeC5H4)3UOPPh3 is instead isolated. Crystals of (MeC5H4)3UOPPh3 are monoclinic, P21/n, with a = 16.268 (3) A, b = 17.948 (3) A, c = 10.900 (2) A, and β = 105.01 (2)0 at 230C; for Z = 4 the calculated density is 1.628 g/cm3. The structure was refined by full-matrix least squares to a conventional R factor of 0.028 [2427 data, F2 > 2 sigma (F2)]. The average U-C distance is 2.82 +/- 0.04 A, the U-O distance is 2.389 (6) A, and the U-O-P angle is 162.8 (4)0