All Calculations Done with the Gaussian 94 Package of Programs

Supplementary Material (ESI) for Chemical Communications This journal is © The Royal Society of Chemistry 2000

SUPPLEMENTARY MATERIAL

Persistent Phosphinyl Radicals from a Bulky Diphosphine: An Example of a Molecular Jack-in-the-Box

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

Michael F. Lappert,c Grete Gundersen,d Jason A. C. Clyburne,e and Philip P. Power.f

a Department of Chemistry, University of Edinburgh, West Mains Road, Edinburgh,

EH9 3JJ.

b Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712, U.S.A.

c School of Chemistry, Physics and Environmental Sciences, University of Sussex, Falmer, Brighton, BN1 9RH.

d Department of Chemistry, University of Oslo, Box 1033, Blindern, N-0315 Oslo, Norway.

e Department of Chemistry, Acadia University, Wolfville, NS, B0P 1X0, Canada.

f Department of Chemistry, The University of California, Davis, Davis, California 95616, U.S.A.

Supplementary Material (ESI) for Chemical Communications This journal is © The Royal Society of Chemistry 2000

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

Summary of Theoretical Results

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.

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

† 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.

2 C. M. Huntley, G. S. Laurenson and D. W. H. Rankin, J. Chem. Soc., Dalton Trans., 1980, 954.

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.

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).

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.