<p>Supplementary Material (ESI) for Chemical Communications This journal is © The Royal Society of Chemistry 2000</p><p>SUPPLEMENTARY MATERIAL</p><p>Persistent Phosphinyl Radicals from a Bulky Diphosphine: An Example of a Molecular Jack-in-the-Box</p><p>Sarah L. Hinchley,a Carole A. Morrison,a David W. H. Rankin,a* Charles L. B. Macdonald,b Robert J. Wiacek, b Alan H. Cowley,b</p><p>Michael F. Lappert,c Grete Gundersen,d Jason A. C. Clyburne,e and Philip P. Power.f</p><p> a Department of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, </p><p>EH9 3JJ.</p><p> b Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712, U.S.A.</p><p> c School of Chemistry, Physics and Environmental Sciences, University of Sussex, Falmer, Brighton, BN1 9RH.</p><p> d Department of Chemistry, University of Oslo, Box 1033, Blindern, N-0315 Oslo, Norway.</p><p> e Department of Chemistry, Acadia University, Wolfville, NS, B0P 1X0, Canada.</p><p> f Department of Chemistry, The University of California, Davis, Davis, California 95616, U.S.A.</p><p>Supplementary Material (ESI) for Chemical Communications This journal is © The Royal Society of Chemistry 2000</p><p>GED data for 2: Electron scattering intensities for 2 were recorded on Kodak Electron Image plates using the Balzers’ gas electron diffraction apparatus in Oslo operating at ca. 41.5 kV (electron wavelength ca. 0.058 Å). Nozzle-to-plate distances for the metal inlet nozzle were ca. 248 and 498 mm, yielding data in the s range 1.5-29 Å-1. Three plates were exposed at the long distance and five at the short distance and the sample and nozzle temperatures were maintained at 420 K during the exposure periods. The scattering patterns of benzene were used for the purpose of calibration of the electron wavelength. The electron-scattering patterns were converted into digital form using a Joyce Loebl microdensitometer. The programs used for data reduction1 and least-squares refinement2 have been described previously; the complex scattering factors were those listed by Ross et al.3</p><p>Summary of Theoretical Results</p><p>All calculations done with the Gaussian 944 package of programs using either the B3LYP5 or UB3LYP DFT approach with a 6-311G* basis set for P and 6-31G* basis sets on all other atoms. All calculations were performed using the resources of the U.K. Computational Chemistry Facility, on a DEC 8400 superscalar cluster equipped with 10 fast processors, 6 GB of memory and 150 GB disk. “Diphosphine” refers to (syn,anti-P[CH(SiMe3)2]2) and “radical” refers to P[CH(SiMe3)2]2.</p><p>Conformational Description Label Energy / a.u. Relative Energy / (kJ/mol) P-P Bond Energy / (kJ/mol) Diphosphine, Single Point Energy† 1 -4111.49606999 258.00 (1/2 of 1) 95.88 † syn,anti-radicals, Single Point Energy 1A1 -2055.73639389 288.56 1A2 -2055.72315900 323.31 ‡ syn,anti-radicals, H Optimized, Heavy Atoms Fixed 1B2 -2055.81424078 84.18 § syn,anti-radicals, Fully Optimized 1C2 -2055.83386190 32.66 syn,syn-radicals, Fully Optimized§ 2 -2055.84630210 0</p><p>† All atoms in the experimentally determined positions. ‡ Heavy atoms fixed in experimentally determined positions, H atoms allowed to optimize. § All atoms allowed to optimize. 1 S. Cradock, J. Koprowski and D. W. H. Rankin, J. Mol. Struct., 1981, 77, 113.</p><p>2 C. M. Huntley, G. S. Laurenson and D. W. H. Rankin, J. Chem. Soc., Dalton Trans., 1980, 954.</p><p>3 A. M. Ross, M. Fink and R. Hilderbrandt, in International Tables for Crystallography, Ed. A. J. C. Wilson, Vol. C, Kluwer Academic Publishers, Dortrecht, 1992, p. 245.</p><p>4 Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Gill, P. M. W.; Johnson, B. G.; Robb, M. A.; Cheeseman, J. R.; Keith, T. A.; Petersson, G. A.; Montgomery, J. A.; Raghavachari, K.; Al-Laham, M. A.; Zakrewski, V. G.; Ortiz, J. V.; Foresman, J. B.; Cioslowski, J.; Stefanow, B. B.; Nanayakkara, A.; Challacombe, M.; Peng, C. Y.; Ayala, P. Y.; Chen, W.; Wong, M. W.; Andres, J. L.; Replogle, E. S.; Gomperts, R.; Martin, R. L.; Fox, D. J.; Binkley, J. S.; DeFrees, D. J.; Baker, J.; Stewart, J. P.; Head-Gordon, M.; Gonzalez, C.; Pople, J. A. GAUSSIAN 94 (Revision B.2) (Gaussian, Inc.; Pittsburgh PA, 1995).</p><p>5 (a) A. D. Becke, J. Chem. Phys., 1993, 98, 5648. (b) A. D. Becke, Phys. Rev. A, 1988, 38, 3098. (c) C. Lee, W. Yang, and R. G. Parr, Phys. Rev. B, 1988, 37, 785. (d) S. H. Vosko, L. Wilk, and M. Nusair, Can. J. Phys., 1980, 58, 1200.</p>