MULTIPLE-BOND CHARACTER IN CP3U=CHPME3 - 1ST LOW-TEMPERATURE NEUTRON-DIFFRACTION ANALYSIS OF A URANIUM ORGANOMETALLIC COMPLEX

The structure of Cp3U=CHPMe3 has been determined from neutron diffraction data at 20 K. Crystal data: space group PĪ, a = 10.352 (2) Å, b = 11.326 (2) Å, c = 8.235 (1) Å, α = 91.23 (1)°, β = 93.14 (1)°, and γ = 64.291 (9)°; V = 869.5 Å3; Z = 2. Data were collected at the Brookhaven High Flux Beam Reactor, with a single-crystal specimen of approximate dimensions 4.3 × 1.4 × 1.2 mm. Final agreement factors are R(F2) = 0.029 and R(wF2) = 0.038 for 2227 independent reflections and 421 parameters varied. The neutron diffraction study was undertaken to investigate a possible metal-hydrogen interaction and the metal-carbon-phosphorus geometry. Bond distances and angles of interest include U–C = 2.293 (1)Å, C–H = 1.082 (2)Å, C–P = 1.692 (2)Å, U···H = 2.859 (3)Å, U–C–P = 141.49 (7)°, and U–C–H = 110.6 (2)°. The α-hydrogen atom is not agostic, and the short U–C bond distance and large U–C–P bond angle indicate multiple-bond character. © 1990, American Chemical Society. All rights reserved.