Decomposition!of!Malonic!Anhydrides. Charles L. Perrin,* Agnes Flach, and Marlon N. Manalo SUPPORTING INFORMATION

S1 Decomposition!of!Malonic!Anhydrides Charles L. Perrin,* Agnes Flach, and Marlon N. Manalo SUPPORTING INFORMATION Complete Reference 26: M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, J. A. Montgomery, Jr., T. Vreven, K. N. Kudin, J. C. Burant, J. M. Millam, S. S. Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G. A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J. E. Knox, H. P. Hratchian, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, P. Y. Ayala, K. Morokuma, G. A. Voth, P. Salvador, J. J. Dannenberg, V. G. Zakrzewski, S. Dapprich, A. D. Daniels, M. C. Strain, O. Farkas, D. K. Malick, A. D. Rabuck, K. Raghavachari, J. B. Foresman, J. V. Ortiz, Q. Cui, A. G. Baboul, S. Clifford, J. Cioslowski, B. B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R. L. Martin, D. J. Fox, T. Keith, M. A. Al-Laham, C. Y. Peng, A. Nanayakkara, M. Challacombe, P. M. W. Gill, B. Johnson, W. Chen, M. W. Wong, C. Gonzalez, and J. A. Pople, Gaussian, Inc., Wallingford CT, 2004. Table S1. Average rate constants (s -1 ) from linear and nonlinear fits for decomposition of malonic anhydrides (2abc) from repeated runs at the same temperature ( C), along with the %variation. anhydride T 10 4 <k lin > %! k T 10 4 <k NL > %! k T 2a 0.8 1.68 4.1 1.67 5.1 2b 10.6 7.7 7.2 7.8 5.3 2b 10.7 7.8 7.9 7.8 7.5 2c 15.6 2.64 1.2 2.85 3.9

S2 Table S2. Energies (hartrees) by different methods. Molecule\Method HF/6-31G(d) a MP2/6-31G(d) a MP2/6-31G(d) MP2/cc-pVDZ 2a -339.351967-340.253535-340.203529-340.252546 Ketene -151.724672-152.147489-152.115475-152.145831 CO 2-187.634176-188.107747-188.096236-188.122014 Ketene + CO 2-339.358848-340.255237-340.211711-340.267845 2a -339.289561-340.200230-340.154030-340.206593 Molecule\Method MP2/aug-cc-pVDZ B3LYP/6-31G(d) B3LYP/cc-pVTZ G3 2a -340.322131-341.129879-341.262332-340.993700 Ketene -152.173303-152.566725-152.632364-152.503369 CO 2-188.158319-188.569348-188.648876-188.497674 Ketene + CO 2-340.331622-341.136073-341.281240-341.001043 2a -340.279818-341.082532-341.220452 Molecule\Method B3LYP/6-311+G(3df,2p) UBPW91/6-311+G(3df,2p) B3LYP/6-31G(d) b UBPW91/6-31G(d) b 2a -341.260977-341.240868-341.138414-341.121137 Ketene -152.631184-152.616386 CO 2-188.648678-188.639562 Ketene + CO 2-341.279862-341.255948 2a -341.219934-341.204252-341.097176-341.083085 Molecule\Method B3LYP/6-31G(d) B3LYP/cc-pVTZ G3 B3LYP/6-311+G(3df,2p) 2b -380.418825-380.565447-380.267619-380.563142 MeKetene -191.851760-191.930592-191.770590-191.928233 MeKetene + CO 2-380.421108-380.579468-380.268264-380.576911 2b -380.373729-380.525302-380.523624 Molecule\Method B3LYP/6-31G(d) B3LYP/cc-pVTZ G3 B3LYP/6-311+G(3df,2p) 2c -419.708158-419.868864-419.544251-419.865735 Me 2 Ketene -231.139278-231.231426-231.041672-231.227986 Me 2 Ketene + CO 2-419.708626-419.880302-419.539346-419.876664 2c -419.660574-419.825530-419.823048 a ZPE-uncorrected. b PCM(solvent=chloroform).

S3 Table S3. Optimized Cartesian coordinates (Å) of malonic anhydride (2a) at the HF/6-31G level. C 0.000268 1.144885 0.000000 H -0.888789 1.760360 0.000000 H 0.889956 1.759480 0.000000 O -0.000253-0.947822 0.000000 O -0.000027-0.174043 2.146164 O -0.000027-0.174043-2.146164 C -0.000027-0.001825-0.993920 C -0.000027-0.001825 0.993920 Table S4. Optimized Cartesian coordinates (Å) of ketene (5a) at the HF/6-31G level. C 0.000000 0.000000 0.106125 O 0.000000 0.000000 1.251094 C 0.000000 0.000000-1.199529 H 0.000000 0.933769-1.724161 H 0.000000-0.933769-1.724161 Table S5. Optimized Cartesian coordinates (Å) of CO 2 at the HF/6-31G level. O 0.000000 0.000000 1.143226 C 0.000000 0.000000 0.000000 O 0.000000 0.000000-1.143226 Table S6. Optimized Cartesian coordinates (Å) of transition-state structure for decomposition of malonic anhydride (2a) at the HF/6-31G level. C 0.081829 1.044596 0.000028 H 0.054803 1.658421-0.891958 H 0.054811 1.658356 0.892059 O 2.285354-0.241212-0.000031 C 1.304126 0.265621 0.000003 O -2.163910 0.192644-0.000036 C -1.028848-0.166157 0.000004

S4 O -0.402976-1.224074 0.000029 Table S7. Optimized Cartesian coordinates (Å) of malonic anhydride (2a) at the MP2/6-31G(d) level. C -0.003847 1.144148 0.000000 H -0.901551 1.766351 0.000000 H 0.890429 1.771317 0.000000 O 0.004140-0.994228 0.000000 C 0.000039 0.006610 1.006937 O 0.000039-0.158004 2.192108 C 0.000039 0.006610-1.006937 O 0.000039-0.158004-2.192108 Table S8. Optimized Cartesian coordinates (Å) of ketene (5a) at the MP2/6-31G(d) level. C 0.000000 0.000000 0.099014 O 0.000000 0.000000 1.280109 C 0.000000 0.000000-1.220977 H 0.000000 0.939401-1.754545 H 0.000000-0.939401-1.754545 Table S9. Optimized Cartesian coordinates (Å) of CO 2 at the MP2/6-31G(d) level. O 0.000000 0.000000 1.179704 C 0.000000 0.000000 0.000000 O 0.000000 0.000000-1.179704 Table S10. Optimized Cartesian coordinates (Å) of transition-state structure for decomposition of malonic anhydride (2a) at the MP2/6-31G(d) level. C 0.162483 1.116568 0.314023 H -0.009814 1.245238 1.381435 H 0.233884 2.057772-0.235094 O -0.363191-1.161260 0.403924

S5 C 1.211170 0.226452 0.040320 O 2.158559-0.290709-0.382819 C -1.014315-0.158284 0.007974 O -2.092881 0.150540-0.436136 Table S11. Optimized Cartesian coordinates (Å) of malonic anhydride (2a) at the MP2/cc-pVDZ level. C 0.000445 1.152572 0.000000 H -0.903624 1.778474 0.000000 H 0.905138 1.777593 0.000000 O -0.000419-0.990622 0.000000 C -0.000030 0.005351 1.008401 O -0.000030-0.163171 2.189385 C -0.000030 0.005351-1.008401 O -0.000030-0.163171-2.189385 Table S12. Optimized Cartesian coordinates (Å) of ketene (5a) at the MP2/cc-pVDZ level. C 0.000000 0.000000 0.104551 O 0.000000 0.000000 1.280409 C 0.000000 0.000000-1.226897 H 0.000000 0.952940-1.754599 H 0.000000-0.952940-1.754599 Table S13. Optimized Cartesian coordinates (Å) of CO 2 at the MP2/cc-pVDZ level. O 0.000000 0.000000 1.177084 C 0.000000 0.000000 0.000000 O 0.000000 0.000000-1.177084 Table S14. Optimized Cartesian coordinates (Å) of transition-state structure for decomposition of malonic anhydride (2a) at the MP2/cc-pVDZ level. C 1.198906 0.207632 0.038917

S6 O 2.148374-0.311056-0.374066 C 0.176910 1.151332 0.282792 H -0.023740 1.266244 1.354602 H 0.311808 2.102085-0.254530 O -2.112500 0.117966-0.419442 C -1.025387-0.159071 0.004258 O -0.334704-1.127870 0.411524 Table S15. Optimized Cartesian coordinates (Å) of malonic anhydride (2a) at the MP2/aug-ccpVDZ level. C 0.001216 1.149550 0.000000 H -0.903156 1.772363 0.000000 H 0.907247 1.769998 0.000000 O -0.001159-1.000533 0.000000 C -0.000075 0.009138 1.013760 O -0.000075-0.159066 2.198686 C -0.000075 0.009138-1.013760 O -0.000075-0.159066-2.198686 Table S16. Optimized Cartesian coordinates (Å) of ketene (5a) at the MP2/aug-cc-pVDZ level. C 0.000000 0.000000 0.104323 O 0.000000 0.000000 1.282901 C 0.000000 0.000000-1.229667 H 0.000000 0.952285-1.755573 H 0.000000-0.952285-1.755573 Table S17. Optimized Cartesian coordinates (Å) of CO 2 at the MP2/aug-cc-pVDZ level. O 0.000000 0.000000 1.180223 C 0.000000 0.000000 0.000000 O 0.000000 0.000000-1.180223 Table S18. Optimized Cartesian coordinates (Å) of transition-state structure for decomposition of

S7 malonic anhydride (2a) at the MP2/aug-cc-pVDZ level. C 0.129171 1.097082 0.291401 H 0.164494 2.029948-0.289100 C 1.238698 0.250983 0.034173 H -0.001807 1.250047 1.370629 O 2.196297-0.272527-0.340734 O -2.113174 0.162599-0.392816 C -1.011617-0.156595 0.008707 O -0.370647-1.193673 0.347648 Table S19. Optimized Cartesian coordinates (Å) of malonic anhydride (2a) at the B3LYP/6-31G(d) level. C 0.000241 1.150157 0.000000 H -0.894894 1.777625 0.000000 H 0.896918 1.775742 0.000000 O -0.001150-0.982069 0.000000 O 0.000205-0.166225 2.184188 O 0.000205-0.166225-2.184188 C 0.000205 0.005154-1.009459 C 0.000205 0.005154 1.009459 Table S20. Optimized Cartesian coordinates (Å) of ketene (5a) at the B3LYP/6-31G(d) level. C 0.000000 0.000000 0.101129 O 0.000000 0.000000 1.272504 C 0.000000 0.000000-1.213710 H 0.000000 0.939296-1.752276 H 0.000000-0.939296-1.752276 Table S21. Optimized Cartesian coordinates (Å) of CO 2 at the B3LYP/6-31G(d) level. O 0.000000 0.000000 1.169167 C 0.000000 0.000000 0.000000

S8 O 0.000000 0.000000-1.169167 Table S22. Optimized Cartesian coordinates (Å) of transition-state structure for decomposition of malonic anhydride (2a) at the B3LYP/6-31G(d) level. C 0.178489 1.122136 0.284077 H 0.273927 2.060485-0.269763 C 1.223641 0.217697 0.044340 H -0.013453 1.274115 1.346624 O 2.167842-0.299842-0.357819 O -2.109225 0.151894-0.403757 C -1.027580-0.158711 0.003053 O -0.372088-1.154719 0.378365 Table S23. Optimized Cartesian coordinates (Å) of malonic anhydride (2a) at the B3LYP/cc-pVTZ level. C 0.001192 1.144825 0.000000 H -0.890169 1.768599 0.000000 H 0.893674 1.767058 0.000000 O -0.001321-0.980528 0.000000 C -0.000003 0.006132 1.008103 O -0.000003-0.164623 2.174166 C -0.000003 0.006132-1.008103 O -0.000003-0.164623-2.174166 Table S24. Optimized Cartesian coordinates (Å) of ketene (5a) at the B3LYP/cc-pVTZ level. C 0.000000 0.000000 0.102046 O 0.000000 0.000000 1.262388 C 0.000000 0.000000-1.205672 H 0.000000 0.937000-1.738672 H 0.000000-0.937000-1.738672 Table S25. Optimized Cartesian coordinates (Å) of CO 2 at the B3LYP/cc-pVTZ level.

S9 O 0.000000 0.000000 1.160338 C 0.000000 0.000000 0.000000 O 0.000000 0.000000-1.160338 Table S26. Optimized Cartesian coordinates (Å) of transition-state structure for decomposition of malonic anhydride (2a) at the B3LYP/cc-pVTZ level. C 0.165466 1.110876 0.261609 H 0.252378 2.036449-0.305720 C 1.219024 0.216360 0.038864 H -0.011263 1.280089 1.320383 O 2.171091-0.286791-0.327834 O -2.111962 0.147023-0.370060 C -1.021592-0.153364 0.002697 O -0.361441-1.155203 0.343683 Table S27. Optimized Cartesian coordinates (Å) of malonic anhydride (2a) at the G3 level. C 0.000058 1.142596 0.000000 H -0.895450 1.768085 0.000000 H 0.895637 1.767985 0.000000 O -0.000057-0.992900 0.000000 C -0.000003-0.158006 2.189813 O -0.000003-0.158006-2.189813 C -0.000003 0.006637-1.005707 O -0.000003 0.006637 1.005707 Table S28. Optimized Cartesian coordinates (Å) of ketene (5a) at the G3 level. C 0.000000 0.000000 0.098880 O 0.000000 0.000000 1.278769 C 0.000000 0.000000-1.219310 H 0.000000 0.938858-1.753790 H 0.000000-0.938858-1.753790

S10 Table S29. Optimized Cartesian coordinates (Å) of CO 2 at the G3 level. O 0.000000 0.000000 1.178670 C 0.000000 0.000000 0.000000 O 0.000000 0.000000-1.178670 Table S30. Optimized Cartesian coordinates (Å) of malonic anhydride (2a) at the B3LYP/6-311+G(3df,2p) level. C 0.000723 1.144974 0.000000 H -0.890983 1.768475 0.000000 H 0.893093 1.767510 0.000000 O -0.000589-0.979608 0.000000 C -0.000062 0.006088 1.007811 O -0.000062-0.165126 2.172864 C -0.000062 0.006088-1.007811 O -0.000062-0.165126-2.172864 Table S31. Optimized Cartesian coordinates (Å) of ketene (5a) at the B3LYP/6-311+G(3df,2p) level. C 0.000000 0.000000 0.102706 O 0.000000 0.000000 1.261574 C 0.000000 0.000000-1.205229 H 0.000000 0.936839-1.738722 H 0.000000-0.936839-1.738722 Table S32. Optimized Cartesian coordinates (Å) of CO 2 at the B3LYP/6-311+G(3df,2p) level. O 0.000000 0.000000 1.159067 C 0.000000 0.000000 0.000000 O 0.000000 0.000000-1.159067 Table S33. Optimized Cartesian coordinates (Å) of transition-state structure for decomposition of

S11 malonic anhydride (2a) at the B3LYP/6-311+G(3df,2p) level. C 0.154056 1.096259 0.258347 H 0.001711 1.281779 1.319069 H 0.217511 2.015588-0.322989 O 2.184676-0.278054-0.313798 C 1.229090 0.223670 0.034602 O -0.372804-1.167787 0.324457 C -1.018578-0.150436 0.004269 O -2.112701 0.156550-0.358082 Table S34. Optimized Cartesian coordinates (Å) of malonic anhydride (2a) at the UBPW91/6-311+G(3df,2p) level. C 0.000051 1.146814 0.000000 H -0.896217 1.776493 0.000000 H 0.896352 1.776443 0.000000 O -0.000053-0.994735 0.000000 C -0.000001 0.008819 1.013153 O -0.000001-0.161360 2.188282 C -0.000001 0.008819-1.013153 O -0.000001-0.161360-2.188282 Table S35. Optimized Cartesian coordinates (Å) of ketene (5a) at the UBPW91/6-311+G(3df,2p) level. C 0.000000 0.000000 0.101569 O 0.000000 0.000000 1.271336 C 0.000000 0.000000-1.212861 H 0.000000 0.942062-1.751467 H 0.000000-0.942062-1.751467 Table S36. Optimized Cartesian coordinates (Å) of CO 2 at the UBPW91/6-311+G(3df,2p) level. O 0.000000 0.000000 1.170053

S12 C 0.000000 0.000000 0.000000 O 0.000000 0.000000-1.170053 Table S37. Optimized Cartesian coordinates (Å) of transition-state structure for decomposition of malonic anhydride (2a) at the UBPW91/6-311+G(3df,2p) level. C 1.218707 0.213829 0.047642 H -0.030396 1.257530 1.348120 H 0.283402 2.069052-0.257755 O 2.167761-0.296897-0.358861 C 0.184389 1.121271 0.285117 O -2.108775 0.156472-0.403553 C -1.023684-0.155331 0.001090 O -0.375171-1.160224 0.375732 Table S38. Optimized Cartesian coordinates (Å) of malonic anhydride (2a) at the B3LYP/6-31G(d) level with PCM (solvent=chloroform). C 0.000145 1.152087 0.000000 H -0.898007 1.778098 0.000000 H 0.898505 1.777805 0.000000 O -0.000143-0.980616 0.000000 O -0.000008-0.171537 2.181977 O -0.000008-0.171537-2.181977 C -0.000008 0.010091 1.006505 C -0.000008 0.010091-1.006505 Table S39. Optimized Cartesian coordinates (Å) of transition-state structure for decomposition of malonic anhydride (2a) at the B3LYP/6-31G(d) level with PCM (solvent=chloroform). C 0.115534 1.048620 0.195390 H 0.109416 1.908190-0.487183 C 1.284210 0.263325 0.018306 H 0.050366 1.383165 1.239613 O 2.269137-0.257196-0.215117

S13 O -2.152062 0.199252-0.254200 C -1.012170-0.139309 0.006090 O -0.427728-1.232952 0.210424 Table S40. Optimized Cartesian coordinates (Å) of malonic anhydride (2a) at the UBPW91/6-31G(d) level with PCM (solvent=chloroform). C 0.000084 1.153422 0.000000 H -0.902378 1.785730 0.000000 H 0.902648 1.785584 0.000000 O -0.000075-0.996544 0.000000 O -0.000006 0.012697 1.011683 O -0.000006-0.166991 2.197181 C -0.000006 0.012697-1.011683 C -0.000006-0.166991-2.197181 Table S41. Optimized Cartesian coordinates (Å) of transition-state structure for decomposition of malonic anhydride (2a) at the UBPW91/6-31G(d) level with PCM (solvent=chloroform). C -0.437732-1.227338 0.296706 H -1.014382-0.141938 0.005123 C -2.130300 0.206207-0.353927 H 1.272251 0.254785 0.037177 O 2.244426-0.270564-0.303683 O 0.142515 1.063810 0.268754 C 0.022773 1.277766 1.344775 O 0.163769 1.995861-0.323870 Table S42. Optimized Cartesian coordinates (Å) of methylmalonic anhydride (2b) at the B3LYP/6-31G(d) level. C -0.269122-0.294990 1.007651 O -0.269122-0.470099 2.183044 C -0.051471 0.835374 0.000000 H -0.886307 1.546348 0.000000

S14 C 1.294418 1.558223 0.000000 H 1.379027 2.190996-0.888361 H 1.379027 2.190996 0.888361 H 2.128947 0.850369 0.000000 O -0.269122-0.470099-2.183044 C -0.269122-0.294990-1.007651 O -0.490371-1.259854 0.000000 Table S43. Optimized Cartesian coordinates (Å) of methylketene (5b) at the B3LYP/6-31G(d) level. C 0.766080 0.128134-0.000001 O 1.871894-0.268568 0.000001 C -0.472871 0.571337-0.000003 H -0.595231 1.650828 0.000009 C -1.686798-0.332826 0.000001 H -2.309269-0.156847-0.885915 H -1.399860-1.388458-0.000002 H -2.309261-0.156849 0.885922 Table S44. Optimized Cartesian coordinates (Å) of transition-state structure for decomposition of methylmalonic anhydride (2b) at the B3LYP/6-31G(d) level. C 1.186798-0.314479 0.116608 O 2.073866-0.849051-0.382552 C 0.208845 0.623477 0.493891 H 0.018686 0.572701 1.568394 C 0.317465 2.033588-0.072808 H 0.708869 2.031924-1.093779 H -0.706671 2.421330-0.109783 H 0.931885 2.695500 0.544670 O -2.091408 0.053029-0.380851 C -1.073723-0.457571 0.009880 O -0.581093-1.582921 0.239038

S15 Table S45. Optimized Cartesian coordinates (Å) of methylmalonic anhydride (2b) at the B3LYP/cc-pVTZ level. C -0.269122-0.294990 1.007651 O -0.269122-0.470099 2.183044 C -0.051471 0.835374 0.000000 H -0.886307 1.546348 0.000000 C 1.294418 1.558223 0.000000 H 1.379027 2.190996-0.888361 H 1.379027 2.190996 0.888361 H 2.128947 0.850369 0.000000 O -0.269122-0.470099-2.183044 C -0.269122-0.294990-1.007651 O -0.490371-1.259854 0.000000 Table S46. Optimized Cartesian coordinates (Å) of methylketene (5b) at the B3LYP/cc-pVTZ level. C 0.766080 0.128134-0.000001 O 1.871894-0.268568 0.000001 C -0.472871 0.571337-0.000003 H -0.595231 1.650828 0.000009 C -1.686798-0.332826 0.000001 H -2.309269-0.156847-0.885915 H -1.399860-1.388458-0.000002 H -2.309261-0.156849 0.885922 Table S47. Optimized Cartesian coordinates (Å) of transition-state structure for decomposition of methylmalonic anhydride (2b) at the B3LYP/cc-pVTZ level. C 1.186798-0.314479 0.116608 O 2.073866-0.849051-0.382552 C 0.208845 0.623477 0.493891 H 0.018686 0.572701 1.568394 C 0.317465 2.033588-0.072808

S16 H 0.708869 2.031924-1.093779 H -0.706671 2.421330-0.109783 H 0.931885 2.695500 0.544670 O -2.091408 0.053029-0.380851 C -1.073723-0.457571 0.009880 O -0.581093-1.582921 0.239038 Table S48. Optimized Cartesian coordinates (Å) of methylketene (5b) at the G3 level. C 0.766080 0.128134-0.000001 O 1.871894-0.268568 0.000001 C -0.472871 0.571337-0.000003 H -0.595231 1.650828 0.000009 C -1.686798-0.332826 0.000001 H -2.309269-0.156847-0.885915 H -1.399860-1.388458-0.000002 H -2.309261-0.156849 0.885922 Table S49. Optimized Cartesian coordinates (Å) of methylmalonic anhydride (2b) at the G3 level. C -0.269122-0.294990 1.007651 O -0.269122-0.470099 2.183044 C -0.051471 0.835374 0.000000 H -0.886307 1.546348 0.000000 C 1.294418 1.558223 0.000000 H 1.379027 2.190996-0.888361 H 1.379027 2.190996 0.888361 H 2.128947 0.850369 0.000000 O -0.269122-0.470099-2.183044 C -0.269122-0.294990-1.007651 O -0.490371-1.259854 0.000000 Table S50. Optimized Cartesian coordinates (Å) of methylmalonic anhydride (2b) at the B3LYP/6-311+G(3df,2p) level.

S17 C -0.269122-0.294990 1.007651 O -0.269122-0.470099 2.183044 C -0.051471 0.835374 0.000000 H -0.886307 1.546348 0.000000 C 1.294418 1.558223 0.000000 H 1.379027 2.190996-0.888361 H 1.379027 2.190996 0.888361 H 2.128947 0.850369 0.000000 O -0.269122-0.470099-2.183044 C -0.269122-0.294990-1.007651 O -0.490371-1.259854 0.000000 Table S51. Optimized Cartesian coordinates (Å) of methylketene (5b) at the B3LYP/6-311+G(3df,2p) level. C 0.766080 0.128134-0.000001 O 1.871894-0.268568 0.000001 C -0.472871 0.571337-0.000003 H -0.595231 1.650828 0.000009 C -1.686798-0.332826 0.000001 H -2.309269-0.156847-0.885915 H -1.399860-1.388458-0.000002 H -2.309261-0.156849 0.885922 Table S52. Optimized Cartesian coordinates (Å) of transition-state structure for decomposition of methylmalonic anhydride (2b) at the B3LYP/6-311+G(3df,2p) level. C 1.186798-0.314479 0.116608 O 2.073866-0.849051-0.382552 C 0.208845 0.623477 0.493891 H 0.018686 0.572701 1.568394 C 0.317465 2.033588-0.072808 H 0.708869 2.031924-1.093779 H -0.706671 2.421330-0.109783 H 0.931885 2.695500 0.544670

S18 O -2.091408 0.053029-0.380851 C -1.073723-0.457571 0.009880 O -0.581093-1.582921 0.239038 Table S53. Optimized Cartesian coordinates (Å) of dimethylmalonic anhydride (2c) at the B3LYP/6-31G(d) level. C -0.000019 0.596097 0.000000 O 0.000050-1.552150 0.000000 O 0.000011-0.733702 2.183547 O 0.000011-0.733702-2.183547 C 0.000011-0.561484-1.006885 C 0.000011-0.561484 1.006885 C 1.276741 1.444528 0.000000 H 1.297564 2.083083-0.888956 H 1.297564 2.083083 0.888956 H 2.179721 0.825733 0.000000 C -1.276802 1.444478 0.000000 H -1.297650 2.083036 0.888955 H -1.297650 2.083036-0.888955 H -2.179764 0.825656 0.000000 Table S54. Optimized Cartesian coordinates (Å) of dimethylketene (5c) at the B3LYP/6-31G(d) level. C 0.000000 0.000000 0.978886 O 0.000000 0.000000 2.156207 C 0.000000 0.000000-0.338033 C 0.000000 1.307836-1.102149 H 0.885543 1.380156-1.748392 H -0.885539 1.380155-1.748399 H -0.000004 2.177082-0.437703 C 0.000000-1.307836-1.102149 H 0.885539-1.380155-1.748399 H 0.000004-2.177082-0.437703

S19 H -0.885543-1.380156-1.748392 Table S55. Optimized Cartesian coordinates (Å) of transition-state structure for decomposition of dimethylmalonic anhydride (2c) at the B3LYP/6-31G(d) level. C 0.148509 0.585471 0.087771 O -0.419216-1.709870 0.359553 O -2.041018-0.390903-0.615858 O 2.199665-0.855502-0.342972 C 1.249153-0.293258-0.028983 C -0.982844-0.702831-0.120686 C 0.133750 1.689821-0.971986 H 0.516827 1.347024-1.937422 H -0.922360 1.948606-1.108297 H 0.690339 2.579185-0.658637 C -0.136664 1.080091 1.520299 H -1.139465 1.516849 1.520879 H -0.114934 0.254754 2.235001 H 0.582721 1.848021 1.824201 Table S56. Optimized Cartesian coordinates (Å) of dimethylmalonic anhydride (2c) at the B3LYP/cc-pVTZ level. C 0.000492-0.559084 1.005492 O 0.000492-0.731134 2.173792 O -0.000168 0.595147 0.000000 O 1.271572 1.440751 0.000000 C 1.291748 2.076730-0.884663 C 1.291748 2.076730 0.884663 C 2.170839 0.825571 0.000000 H 0.000492-0.731134-2.173792 H 0.000492-0.559084-1.005492 H 0.001358-1.547801 0.000000 C -1.273993 1.437793 0.000000 H -1.295761 2.073871 0.884606

S20 H -1.295761 2.073871-0.884606 H -2.171908 0.820634 0.000000 Table S57. Optimized Cartesian coordinates (Å) of dimethylketene (5c) at the B3LYP/cc-pVTZ level. C 0.000000 0.000000 0.974735 O 0.000000 0.000000 2.142309 C 0.000000 0.000000-0.334150 C 0.000000 1.303984-1.096517 H 0.882008 1.375248-1.739103 H -0.882008 1.375248-1.739103 H 0.000000 2.167860-0.433683 C 0.000000-1.303984-1.096517 H 0.000000-2.167860-0.433683 H -0.882008-1.375248-1.739103 H 0.882008-1.375248-1.739103 Table S58. Optimized Cartesian coordinates (Å) of transition-state structure for decomposition of dimethylmalonic anhydride (2c) at the B3LYP/cc-pVTZ level. C 1.241061-0.308992-0.037571 O 2.189559-0.866855-0.319172 O 0.147918 0.574228 0.077141 O 0.144368 1.668227-0.988961 C 0.484154 1.303275-1.956806 C 0.743265 2.532068-0.700214 C -0.898226 1.970223-1.097519 H -0.430437-1.710255 0.318435 H -0.993391-0.684959-0.110845 H -2.064391-0.362961-0.555071 C -0.099289 1.091712 1.505304 H -1.087640 1.548234 1.516696 H 0.639124 1.843945 1.783649 H -0.082527 0.281524 2.230260

S21 Table S59. Optimized Cartesian coordinates (Å) of dimethylmalonic anhydride (2c) at the G3 level. C -0.000019 0.596097 0.000000 O 0.000050-1.552150 0.000000 O 0.000011-0.733702 2.183547 O 0.000011-0.733702-2.183547 C 0.000011-0.561484-1.006885 C 0.000011-0.561484 1.006885 C 1.276741 1.444528 0.000000 H 1.297564 2.083083-0.888956 H 1.297564 2.083083 0.888956 H 2.179721 0.825733 0.000000 C -1.276802 1.444478 0.000000 H -1.297650 2.083036 0.888955 H -1.297650 2.083036-0.888955 H -2.179764 0.825656 0.000000 Table S60. Optimized Cartesian coordinates (Å) of dimethylketene (5c) at the G3 level. C 0.000000 0.000000 0.977231 O 0.000000 0.000000 2.162828 C 0.000000 0.000000-0.342743 C 0.000000 1.300376-1.104051 H 0.885059 1.368815-1.746501 H -0.885059 1.368815-1.746501 H 0.000000 2.166618-0.437467 C 0.000000-1.300376-1.104051 H 0.000000-2.166618-0.437467 H -0.885059-1.368815-1.746501 H 0.885059-1.368815-1.746501 Table S61. Optimized Cartesian coordinates (Å) of dimethylmalonic anhydride (2c) at the B3LYP/6-311+G(3df,2p) level.

S22 C 0.000013-0.558883 1.005602 O 0.000013-0.733245 2.172280 O -0.000019 0.595333 0.000000 O 1.273485 1.440033 0.000000 C 1.293520 2.075967-0.884702 C 1.293520 2.075967 0.884702 C 2.172611 0.824479 0.000000 H 0.000013-0.733245-2.172280 H 0.000013-0.558883-1.005602 H 0.000055-1.545776 0.000000 C -1.273562 1.439984 0.000000 H -1.293619 2.075911 0.884705 H -1.293619 2.075911-0.884705 H -2.172655 0.824382 0.000000 Table S62. Optimized Cartesian coordinates (Å) of dimethylketene (5c) at the B3LYP/6-311+G(3df,2p) level. C 0.000000 0.000000 0.975121 O 0.000000 0.000000 2.141679 C 0.000000 0.000000-0.333635 C 0.000000 1.304217-1.096524 H 0.882102 1.375058-1.738696 H -0.882102 1.375058-1.738696 H 0.000000 2.168865-0.434638 C 0.000000-1.304217-1.096524 H 0.000000-2.168865-0.434638 H -0.882102-1.375058-1.738696 H 0.882102-1.375058-1.738696 Table S63. Optimized Cartesian coordinates (Å) of transition-state structure for decomposition of dimethylmalonic anhydride (2c) at the B3LYP/6-311+G(3df,2p) level. C 0.143157 0.565937 0.072395

S23 O 2.199065-0.860204-0.315185 O -2.076436-0.353032-0.521672 O -0.436996-1.718296 0.300293 C 1.247869-0.305365-0.047829 C -0.996886-0.681772-0.102725 C 0.127062 1.656826-0.999211 H 0.423002 1.279298-1.976559 H -0.910935 1.983186-1.071582 H 0.756606 2.506608-0.735267 C -0.074205 1.095651 1.502847 H -1.058309 1.560612 1.526149 H -0.052417 0.291234 2.234181 H 0.674999 1.843664 1.762725