CYCLOPENTADIENYL-RUTHENIUM AND -OSMIUM CHEMISTRY .40. X-RAY CRYSTAL-STRUCTURES OF MBR(PPH(3))(2)(ETA-C5H5)CENTER-DOT-CH2CL2 (M=RU, OS)

The crystal and molecular structures of MBr(PPh3)(2)(eta-C5H5).CH2Cl2 (M = Ru and Os) have been determined. A revised synthesis of the bromo osmium complex is given. The coordination geometry about the metal at om is based on a distorted octahedron with one face being occupied by the cyclopentadienyl group [average Ru-C(Cp) 2 . 214(3), Os-C(Cp) 2 . 177(3) Angstrom] and the other by the bromide [Ru-Br 2 . 5683(8), Os-B r 2 . 5438(9) Angstrom] and the two phosphorus atoms [Ru-P 2 . 323(2), 2 . 329(1); Os-P 2 . 290(2), 2 . 297(2) Angstrom]. Structural paramet ers are compared with those of the corresponding chloro complexes and differ only minimally. Crystals of MBr(PPh(3))(2)(eta-C5H5).CH2Cl2 are triclinic, space group P (1) over bar, with unit cell dimensions (Ru [Os]): a 14 . 374(5) [14 . 276(4)], b 14 . 057(4) [13 . 959(3)], c 10 . 012(5) [9 . 903(3)] Angstrom, alpha 99 . 43(3) [99 . 79(2)], beta 10 5 . 60(3) [105 . 74(2)], gamma 100 . 42(3) [100 . 39(2)]degrees, V 186 8(1) [1817 . 7(9)] Angstrom(3), Z 2. The structures were refined by a full-matrix least-squares procedure to R 0 . 050 [0 . 036] for 7365 [5 108] reflections with I greater than or equal to 3 sigma(I).