1 Synthesis and Characterization of Phosphido-Monolayer-Protected Gold Nanoclusters Diana M. Stefanescu, a David S. Glueck,* a Renée Siegel, b and Roderick E. Wasylishen b a 6128 Burke Laboratory, Department of Chemistry and Center for Nanomaterials Research, Dartmouth College, Hanover, New Hampshire, 03755 b Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2 Supporting Information 1. Synthesis and Characterization of Au-phosphido MPCs 2. Monitoring Cluster Synthesis by 31 P NMR Spectroscopy 3. Reactions of the Clusters with Dodecanethiol 4. Reactions of the Clusters with Iodine General Experimental Details. Unless otherwise noted, all solution NMR spectra were recorded on a Varian 300 or 500 MHz spectrometer. 1 H NMR shifts are reported relative to Me 4 Si and were determined by reference to the solvent peak. 31 P NMR chemical shifts are reported relative to H 3 PO 4 (85%) used as an external reference. Solid state NMR spectra were recorded at the University of Alberta on a Chemagnetics CMX-200 or Bruker Avance 300 spectrometer. The experimental parameters were usually set between the following values: spinning rate: 5-15 kHz, recycle delay: 2-5 s, 1 H rf field ~ 50-60 kHz, contact times: 0.5-3 ms. IR spectra were recorded on KBr pellets using a Perkin Elmer 1600 series FTIR instrument. The TEM images of the particles were obtained with a JEOL 2000FX microscope. TEM samples were prepared by adding one drop of 1 mg cluster/1 mL toluene solution on 400 mesh carbon coated copper grids. The microscope was operated at 120 kV in order to obtain a better contrast. After examination of several grids to find where particles could be observed as distinct features, typical regions of the sample were imaged at a magnification of 150-250K. Size distributions of the gold clusters were obtained from typical regions of digitized photographic enlargements using NIH Image (available at http://rsb.info.nih.gov/nih-image). The particles usually have an elliptical shape. The major and minor axes were measured and their average is reported as the diameter of the particle. Statistical size distributions, as well as standard deviations, were calculated and plotted using Kaleidagraph (available at www.kaleidagraph.com). For a given cluster sample, the average diameter of the gold core and its standard deviation are reported: ave. ± s.d. TGA experiments were done on a TA Instruments Q 50-0135 machine. In TGA, about 2–16 mg of cluster were heated in air to 800 °C, at a rate of 20 °C/min. The initial black color of the cluster disappeared and only gold could be observed at the end of the heating. XPS spectra were done on a Perkin-Elmer PHI 5100 spectrometer. The UV-