Supporting Information

Transkript

1 Supporting Information The F/Ph Rearrangement Reaction of [(Ph 3 P) 3 RhF], the Fluoride Congener of Wilkinson s Catalyst Stuart A. Macgregor,* D. Christopher Roe, William J. Marshall, Karen M. Bloch, Vladimir I. Bakhmutov, ý and Vladimir V. Grushin* Contribution from Central Research & Development, E. I. DuPont de Nemours and Co., Inc., Experimental Station, Wilmington, Delaware , School of Engineering and Physical Sciences, William H. Perkin Building, Heriot-Watt University, Edinburgh EH14 4AS, U.K., and Department of Chemistry, Texas A&M University, P.O. Box 312, College Station, Texas DuPont CR&D. Heriot-Watt University. ý Texas A&M University. S 1

2 Kinetic Studies One-dimensional 31 P, 19 F NMR and kinetic data for equilibrium 1 (see below) were acquired on a Varian Unity Inova system operating at MHz. For the kinetic data obtained by 19 F NMR, the transmitter was placed at 1 ppm, approximately centered between the Rh-F region (-2 to 285 ppm) and the P-F region (-11 to -13 ppm). A spectral width of KHz was used in order to observe additional decomposition products. An acquisition time of.5 sec was used in conjunction with a recycle delay of 1 sec and a pulse width of 55 degrees. Temperature calibration using an ethylene glycol standard indicated insignificant deviations (< ±.2 C) from the thermocouple set point in the range used for the kinetic data. Ph 2 P Ph 3 P Rh F PPh 3 F Ph 2 P Ph 3 P Rh PPh 3 (1) 1 5 The approach to equilibrium could be studied from both sides. It was established that 3.6 mg of 1 in 1 ml of C 6 D 6 could be maintained in solution at slightly elevated temperature. Storage of solutions of 1 in a refrigerator while awaiting kinetic study led to the formation of needle-like crystals that redissolved slowly and hampered the kinetic analysis at 3 and 5 C. The data at C was acquired promptly after the initial dissolution of 1, while the higher temperatures ( and 7 C) appeared to be sufficient to dissolve any crystals present. The results at C will therefore be described first and are presented in Figure 1. The time dependence of the approach to equilibrium starting from 1 is shown in Figure 1A, while the corresponding data starting from 5 is given in Figure 1B. The approach to equilibrium was modeled according to standard kinetic equations: A(t) = (A init A eqm ) exp( (k 1 + k -1 ) t ) + A eqm B(t) = (B init B eqm ) exp( (k 1 + k -1 ) t ) + B eqm where A and B are the observed intensities at time t, the subscripts init and eqm refer to initial and equilibrium intensities, k 1 is the forward rate constant (1 going to 5), and k -1 is the reverse rate constant. The parameters in the above equations were obtained by a nonlinear least- S 2

3 squares fit to the combined data sets, and led to the single best-fitting rate constant (k 1 + k -1 ) and equilibrium intensities consistent with the entire data set. The best-fitting parameters were used to obtain the smooth curves in Figure 1 (and subsequent kinetic plots, Figures 2-5), and the rate constant of interest (k 1 ) was obtained from the equilibrium intensities: k 1 = (k 1 + k -1 ) / (1 + A eqm /B eqm ). At 3 C, only the reverse reaction could be analyzed due to the evident lack of solubility of 1 (Figure 2A). At 5 C (Figure 3A) it appeared that 1 continued to come into solution during the time period encompassed by the first 4-5 points, and the first 4 points were therefore omitted from the analysis. At C, the data appeared to be well behaved (Figure 4), while at 7 C (Figure 5) we are at the limit of our ability to obtain meaningful data. The trend in the values obtained for A eqm and B eqm in the range 3 C is for K eq to decrease slightly from.9 to.6, whereas at 7 C the estimated parameters lead to K eq closer to 1.2. The data at 7 C is therefore somewhat suspect, although the rate estimate at this temperature does not appear to have a significant impact on the activation parameters. The rate constants obtained in C 6 D 6 by this approach are presented in Table 1. In view of the possibility of solvent participation in the reaction, the reaction at C was repeated in THF-d 8 and led to a rate constant of 19.1 x 1-5 sec -1. It was concluded that the reaction is not strongly influenced by solvent. The data in Table 1 are well described by the transition state (Eyring) treatment of the temperature dependence of reaction rate constants as judged by the linearity of the corresponding Eyring plot in Figure 6. The activation enthalpy ( H ) and entropy ( S ) were determined by direct nonlinear least-squares fitting of these parameters to the Eyring equation (k 1 = (k B T/h) exp( S /R) exp(- H /RT)) using the temperature and rate constant data in Table 1 (T was converted to absolute temperature (K); k B is Boltzmann s constant, h is Planck s constant and R is the universal gas constant). This fitting procedure gave the parameter estimates H = 22. ± 1.2 kcal mol -1 and S = 1. ± 3.7 e.u. (the corresponding Arrhenius parameters are E a = 22.7 ± 1.2 kcal mol -1 and log (A/s -1 ) = 11.1 ±.8). The stated uncertainties represent 95% confidence limits and were obtained using an estimated error in the rate constants of 1% and an estimated error in temperature of 2 C. When the rate constant at 7 C was omitted from the analysis, the estimated activation parameters were H = 21.8 ± 2.6 kcal mol -1 and S = 1.8 ± 8. e.u. S 3

4 A B Figure 1. (A) The approach to equilibrium at C starting from 1 (circles), and (B) starting from 5 (squares). In the latter case, a small amount of 1 is present initially as an impurity. S 4

5 A B 5 15 Figure 2. (A) The approach to equilibrium at 3 C starting from 1 (circles), and (B) starting from 5 (squares). The data in (A) was unsuited to analysis due to the limited solubility of 1. S 5

6 A B Figure 3. (A) The approach to equilibrium at 5 C starting from 1 (circles), and (B) starting from 5 (squares). In (A), the first 4 data points for 1 (dashed circles) were omitted from the analysis. S 6

7 A B Figure 4. (A) The approach to equilibrium at C starting from 1 (circles), and (B) starting from 5 (squares). S 7

8 A 3 5 B 3 5 Figure 5. (A) The approach to equilibrium at 7 C starting from 1 (circles), and (B) starting from 5 (squares). S 8

9 Table 1. Estimated rate constants for the conversion of I to II as a function of temperature. Temperature ( C) k 1 (sec -1, x 1 5 ) ln ( k / T ) /T K 1 Figure 6. Eyring plot for the rate data presented in Table 1. S 9

10 Computational Studies Calculations employed the Gaussian 98 program. 1 Rh and P centres were described using the Stuttgart RECPs and the associated basis sets 2 while for P an extra set of polarisation functions was added (ζ =.387) G** basis sets were used for C, F and H atoms. 4 All stationary points were characterized by computation of the Hessian matrix to be either minima (all positive eigenvalues) or transition states (1 imaginary eigenvalue). Transition states were further characterized by IRC calculations to give the local minima described in the main text. All energies include a correction for zero-point energies. Calculations including of general solvation effects were ran with Gaussian 3. 5 Single point energy calculations based on the previously optimized geometry were run incorporating the PCM approach and the dielectric constant of DMSO inlaid in the program (ε = 46.7). The relative energies given in Figures include a correction for zero-point energies derived from frequency calculations on the relevant stationary point calculated in vacuo. (1) Gaussian 98, Revision A.11.4, Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Zakrzewski, V. G.; Montgomery, J. A. Jr.; Stratmann, R. E.; Burant, J. C.; Dapprich, S.; Millam, J. M.; Daniels, A. D.; Kudin, K. N.; Strain, M. C.; Farkas, O.; Tomasi, J.; Barone, V.; Cossi, M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo, C.; Clifford, S.; Ochterski, J.; Petersson, G. A.; Ayala, P. Y.; Cui, Q.; Morokuma, K.; Rega, N.; Salvador, P.; Dannenberg, J. J.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Cioslowski, J.; Ortiz, J. V.; Baboul, A. G.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Gomperts, R.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.; Andres, J. L.; Gonzalez, C.; Head-Gordon, M.; Replogle, E. S.; Pople, J. A. Gaussian, Inc. Pittsburgh PA, 1. (2) Andrae, D.; Häusserman, U.; Dolg, M.; Stoll, H.; Preuss Theor. Chim. Acta 199, 77, 123 (3) Höllwarth, A.; Böhme, M.; Dapprich, S.; Ehlers, A. W.; Gobbi, A.; Jonas, V.; Köhler, K. F.; Stegmann, R.; Veldkamp, A.; Frenking, G. Chem. Phys. Lett. 1993, 8, 237 (4) Hehre, W. J.; Ditchfield, R.; Pople, J. A. J. Chem. Phys. 1972, 56, 2257; Hariharan, P. C.; Pople, J. A. Theor. Chim. Acta 1973, 28, 213 S 1

11 Gaussian 3, Revision C.1, Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Montgomery, Jr., J. A.; Vreven, T.; Kudin, K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith, T.; Al- Laham, M. A.; Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.; Gonzalez, C.; Pople, J. A. Gaussian, Inc., Wallingford CT, 4. S 11

12 Cartesian Coordinates (Å), Computed Energies (including zero-point energies, hartrees) and Transition State Unique Imaginary Frequencies (cm -1 ). cis-1 E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Rh F P P P C H H H H H H H H C C C C C H H H H H I1 E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Rh C P P P F C C C C C H H H H H H H H H H H H H TS (cis-1 I1) E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Nimag = 1 (-197. cm -1 ) Rh F P P P C C C C C C H H H H H H H H H H H H H TS (I1 I2) E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Nimag = 1 ( cm -1 ) Rh C P P P F C C C C C H H H H H H H H H H H H H S 12

13 I2 E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Rh C P P P F C C C C C H H H H H H H H H H H H H cis-5 E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Rh C P P P F C C C C C H H H H H H H H H H H H H TS (I2-cis-5 ) E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Nimag = 1 ( cm -1 ) Rh C P P P F C C C C C H H H H H H H H H H H H H TS (cis-1 -I5) E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Nimag = 1 (-69.5 cm -1 ) Rh F P P P C H H H H H H H H C C C C C H H H H H S 13

14 I5 E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Rh F P P P C H H H H H H H H C C C C C H H H H H TS (cis-1 I6) E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Nimag = 1 ( cm -1 ) Rh F P P P C H H H H H H H H C C C C C H H H H H TS (I5 - cis-5 ) E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Nimag = 1 (-.75 cm -1 ) Rh F P P P C H H H H H H H H C C C C C H H H H H I6 E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Rh F P P P C C C C C C H H H H H H H H H H H H H S 14

15 TS (I6-I3) E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Nimag = 1 ( cm -1 ) Rh P P P F C C C C C C H H H H H H H H H H H H H Rh(PH 3 ) 2 (PH 2 Ph) Radical E = E + ZPE = Rh P P P C H H H H H H H H C C C C C H H H H H F radical E = Ph Radical E = E + ZPE = C C C C C C H H H H H Rh(PH 3 ) 2 (PH 2 F) Radical E = E + ZPE = Rh P P P F H H H H H H H H S 15

16 trans-1 E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Rh F P P P C C C C C C H H H H H H H H H H H H H I3 E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Rh F P P P C C C C C C H H H H H H H H H H H H H TS (trans-1 -I3) E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Nimag = 1( cm -1 ) Rh F P P P C C C C C C H H H H H H H H H H H H H TS(I3 I4) E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Nimag = 1 (-156.7cm -1 ) Rh F P P C C C C C C P H H H H H H H H H H H H H S 16

17 I4 E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Rh F P P C C C C C C P H H H H H H H H H H H H H TS(I4 cis-5 ) E = E + ZPE = E (DMSO) = E (DMSO) +ZPE = Nimag = 1 (-.98 cm -1 ) Rh F P P C C C C C C P H H H H H H H H H H H H H S 17