1 Supporting Information Variable coordination behaviour of pyrazole-containing N,P and N,P(O) ligands towards palladium(II) Steven Kealey, a Nicholas J. Long,* a Philip W. Miller, a Andrew J. P. White, a Peter B. Hitchcock, b Antony Gee a, c a Department of Chemistry, Imperial College London, South Kensington, London, UK SW7 2AZ Email: n.long@imperial.ac.uk ; Tel: +44 (0)20 7594 5781 b Department of Chemistry, School of Life Sciences, University of Sussex, Falmer, Brighton, UK BN1 7QJ c GSK Clinical Imaging Centre, Imperial College London, Hammersmith Hospital, Du Cane Road, London, UK W12 0NN 1.0 Crystal data Diffraction data for compound 1c was collected on an Oxford Diffraction Xcalibur 3 diffractometer and Mo-K α radiation by Dr Andrew J. P. White. The two N–H hydrogen atoms were found from ΔF maps and refined subject to an N–H distance constraint of 0.90 Å. Diffraction data for pzphos(O), 1b, 2b and 2c were collected on a Brucker KappaCCD diffractometer using crystals coated in oil and cooled in a stream of cold nitrogen gas, and Mo-K α radiation by Dr Peter B. Hitchcock. Structure solution and refinement were using SHELXL-97 and other programs in the WinGX package. Empirical absorption corrections were made using MULTISCAN. For pzphos(O) the H atom on N(1) was refined. For 1b there are two water molecules of which one is disordered over two positions, and the H atom on N(1) and N(3) were refined and H atoms for the water molecules were omitted. For 2b the H atom on N(1) was refined. For 2c a disordered CHCl 3 solvate molecule was included with SADI restraints, and the H atom on N(1) was refined. Full details are shown in the Table.