What can NMR spectroscopy of selenoureas and phosphinidenes teach us about the π-accepting abilities of N-heterocyclic carbenes?† †Electronic supplementary information (ESI) available: Full characterisation data including NMR spectra for new compounds; full DFT data and co-ordinates from computational studies. CCDC 1024807–1024818. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4sc03264k Click here for additional data file. Click here for additional data file.

SUPPORTING INFORMATION FOR What can NMR spectroscopy of selenoureas and phosphinidenes teach us about the -accepting abilities of Nheterocyclic carbenes? Sai V. C. Vummaleti,† David J. Nelson,‡,§ Albert Poater,¤ Adrián Gómez Suárez,‡ David B. Cordes,‡ Alexandra M. Z. Slawin,‡ Steven P. Nolan,‡,* and Luigi Cavallo.†,* † KAUST Catalyst Center, Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia; ‡ EaStCHEM School of Chemistry, University of St Andrews, Purdie Building, North Haugh, St Andrews, Fife, KY16 9ST, UK; § WestCHEM Department of Pure and Applied Chemistry, University of Strathclyde, Thomas Graham Building, 295 Cathedral Street, Glasgow, G1 1XL, UK; ¤ Institut de Química Computacional I Catàlisi and Department de Química, Universitat de Girona, Campus de Mo-tilivi, E-17071, Girona, Spain