S1 - Supplementary Information - Synthesis and Structure of [U{C(PPh 2 NMes) 2 } 2 ] (Mes = 2,4,6-Me 3 C 6 H 2 ): A Homoleptic Uranium Bis(Carbene) Complex with two U=C Double Bonds Oliver J. Cooper, Jonathan McMaster, William Lewis, Alexander J. Blake, and Stephen T. Liddle* School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, UK. Fax: +44-115-951-3563; Tel: +44-115-846-7167; E-mail: stephen.liddle@nottingham.ac.uk Experimental General All manipulations were carried out using standard Schlenk techniques, or an MBraun UniLab glovebox, under an atmosphere of dry nitrogen. Solvents were dried by passage through activated alumina towers and degassed before use. All solvents were stored over potassium mirrors. Deuterated solvent was distilled from potassium, degassed by three freeze-pump-thaw cycles and stored under nitrogen. H 2 C(PPh 2 NMes) 2 1 and [UI 3 (THF) 4 ], 2 were prepared according to published procedures. Bu t Li was purchased as a 1.0 M solution in pentane, pumped down to dryness, and stored in the glovebox. Electronic Supplementary Information for Dalton Transactions This journal is © The Royal Society of Chemistry 2010