High-Level Systematic ab Initio Comparison of Carbon- and Silicon-Centered SN2 Reactions Attila Á. Dékány, Gyula Z. Kovács, and Gábor Czakó* MTA-SZTE Lendület Computational Reaction Dynamics Research Group, Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary * E-mail: gczako@chem.u-szeged.hu 6 F/Cl Si-XDITS Cl 0.0000000000 0.0889662481 -2.1462095278 H 0.0000000000 -0.2711821606 -0.4069055551 Si 0.0000000000 -0.6396102883 1.3723702286 F 0.0000000000 0.9020094922 1.9176828174 H 1.2808001325 -1.0187859085 0.7555448378 H -1.2808001325 -1.0187859085 0.7555448378 6 F/Br Si-XDITS Br 0.0000000000 0.0359776624 -1.4923088940 H 0.0000000000 -0.3204807491 0.4873235186 Si 0.0000000000 -0.6378088839 2.2496245233 F 0.0000000000 0.9129067263 2.7588135649 H 1.2598237694 -0.9833533001 1.5652596088 H -1.2598237694 -0.9833533001 1.5652596088 6 F/I Si-XDITS I 0.0000000000 -0.0208436132 -1.1797373796 H 0.0000000000 0.3513179880 1.1212626852 Si 0.0000000000 0.6340182458 2.8647206402 F 0.0000000000 -0.9168583074 3.3615483106 H -1.2366938006 0.9440957753 2.1150651284 H 1.2366938006 0.9440957753 2.1150651284 6 Cl/Br Si-XDITS Br 0.0000000000 0.0907250809 -1.7506901985 H 0.0000000000 -0.5399970000 0.0181080629 Si 0.0000000000 -1.1511618607 1.7320290703 Cl 0.0000000000 0.8072184566 2.5123123109 H 1.2717025358 -1.4843997621 1.0690055775 H -1.2717025358 -1.4843997621 1.0690055775 6 Cl/I Si-XDITS I 0.0000000000 0.0499757776 -1.4048966886 H 0.0000000000 -0.6010325585 0.6285678262 Si 0.0000000000 -1.1534423340 2.3540531484 Cl 0.0000000000 0.8347384909 3.0531122270 H 1.2529561281 -1.4561235462 1.6363424857 H -1.2529561281 -1.4561235462 1.6363424857 6 Br/I Si-XDITS I 0.0000000000 0.0891298434 -1.9620930229 H 0.0000000000 -0.8127716255 -0.0563497797 Si 0.0000000000 -1.5896935260 1.5853076126 Br 0.0000000000 0.4737309919 2.5382227268 H 1.2570431417 -1.8341850969 0.8525762350 H -1.2570431417 -1.8341850969 0.8525762350 6 F/Cl Si-YDITS F 0.0000000000 -0.5380644207 -2.8007271688 H 0.0000000000 -0.0987064823 -1.9411276843 Si 0.0000000000 1.0498549373 0.1494674982 Cl 0.0000000000 -0.6254189686 1.4556523190 H -1.3193522058 1.4927142336 -0.3170959596 H 1.3193522058 1.4927142336 -0.3170959596 6 F/Br Si-YDITS F 0.0000000000 -0.8103727603 -3.2419680929 H 0.0000000000 -0.2304730081 -2.4721259934 Si 0.0000000000 1.2714768906 -0.6201139568 Br 0.0000000000 -0.2927057602 1.0490290856 H -1.3184227253 1.6401710914 -1.1515757427 H 1.3184227253 1.6401710914 -1.1515757427 6 F/I Si-YDITS F 0.0000000000 -1.0047168955 -3.5055749419 H 0.0000000000 -0.3493205011 -2.8024104451 Si 0.0000000000 1.3644820760 -1.1385115856 I 0.0000000000 -0.1757034142 0.8262226784 H -1.3126123298 1.6943772976 -1.7121382599 H 1.3126123298 1.6943772976 -1.7121382599 6 Cl/Br Si-YDITS Cl 0.0000000000 0.4120226227 -2.9009890633 H 0.0000000000 -0.4769021477 -1.5281842980 Si 0.0000000000 -1.4894214592 0.0354746118 Br 0.0000000000 0.3916536766 1.3091187186 H 1.2925913119 -1.7810079369 -0.6007604405 H -1.2925913119 -1.7810079369 -0.6007604405 6 Cl/I Si-YDITS Cl 0.0000000000 0.5580716308 -3.2025665389 H 0.0000000000 -0.4629205574 -1.9743000215 Si 0.0000000000 -1.6773489468 -0.5241258841 I 0.0000000000 0.2499269175 1.0449999778 H 1.2918289440 -1.9478386464 -1.1733015823 H -1.2918289440 -1.9478386464 -1.1733015823 6 Br/I Si-YDITS Br 0.0000000000 0.2221180254 -2.7052778062 H 0.0000000000 -0.7961062601 -1.1859600771 Si 0.0000000000 -1.8189087276 0.3401675918 I 0.0000000000 0.3018662873 1.6431591217 H 1.2736752451 -2.0681748031 -0.3579816609 H -1.2736752451 -2.0681748031 -0.3579816609 6 F/Cl Si-FSTS F -0.9816791398 0.0050460719 -1.1878547824 Si 0.6439633093 -0.0049164306 -0.8000251367 Cl -0.0925061886 0.0045747945 1.3643369446 H 0.9482782181 -1.4149602416 -1.1942400310 H 1.9703155986 0.3518448118 -0.1499133087 H 0.8950521313 0.9440834564 -1.9629759118 6 Cl/Br Si-FSTS Cl -0.7177324764 0.0035027015 -1.9772850240 Si 1.2180747711 -0.0038322767 -0.8239834752 Br -0.1802467097 0.0019330385 1.2029065921 H 1.5581049473 -1.4360501671 -1.0069072173 H 2.2662416059 0.4891640689 0.1417706829 H 1.7692042441 0.7772258199 -1.9865952077 6 Cl/I Si-FSTS Cl -0.8110204836 0.0022875996 -2.3466570205 Si 1.2283250692 -0.0026084998 -1.3962959640 I -0.0893360290 0.0010046182 1.0019964025 H 1.5310336509 -1.4095371511 -1.7596679424 H 2.3789622292 0.3169358910 -0.4791905918 H 1.6381617180 0.9583346189 -2.4707993968 6 Br/I Si-FSTS Br -0.3786470867 0.0014155421 -2.0887022104 Si 1.5912306511 -0.0028288131 -0.6239926439 I -0.1666793678 0.0011179329 1.4694959407 H 1.9198083128 -1.4380996046 -0.7827178826 H 2.5180068507 0.4731073894 0.4567556321 H 2.2266888790 0.7908443867 -1.7239249758 6 F/Cl Si-FSPreMIN Cl 0.0000000000 0.1213873126 -1.3409349989 Si 0.0000000000 -0.6594064313 0.7439042898 F 0.0000000000 0.9537914782 1.2400541417 H 1.2859428372 -0.9143449077 1.4884757892 H 0.0000000000 -2.0448541949 0.0869175588 H -1.2859428372 -0.9143449077 1.4884757892 6 F/Br Si-FSPreMIN F -1.0172941464 -0.0011669496 -1.6921412059 Si 0.6296657222 0.0013188539 -1.4308439151 Br -0.0258706901 -0.0006162134 0.9716519116 H 0.8223150114 -1.1949177378 -2.3289978833 H 2.0117806031 -0.0895332111 -0.8157698080 H 0.8463408597 1.3185476413 -2.1183699986 6 Cl/Br Si-FSPreMIN Br 0.0000000000 0.2441568984 -1.1688594152 Si 0.0000000000 -1.2718877582 0.5768047040 Cl 0.0000000000 0.6164698555 2.1194067996 H 1.2917236884 -1.5882031379 1.2312069907 H 0.0000000000 -2.4223545290 -0.4212558414 H -1.2917236884 -1.5882031379 1.2312069907 6 Cl/I Si-FSPreMIN I 0.0000000000 0.1192286458 -0.9752009704 Si 0.0000000000 -1.2837945450 1.1963503326 Cl 0.0000000000 0.7503738946 2.4273948936 H 1.2872983737 -1.5599330025 1.8830524403 H 0.0000000000 -2.5131607443 0.3013403982 H -1.2872983737 -1.5599330025 1.8830524403 6 Br/I Si-FSPreMIN I -0.2628564967 0.0000000000 -1.5086580790 Si 1.7049448440 0.0000000000 0.0056741572 Br -0.2640715847 0.0000000000 2.3889312398 H 1.8670084557 1.2712408627 0.7213999247 H 2.7882526160 0.0000000000 -1.0337143361 H 1.8670084557 -1.2712408627 0.7213999247 6 F/Cl Si-FSPostMIN F -0.9881208040 0.0000000000 -1.2133049641 Si 0.6092999488 0.0000000000 -0.9449154292 Cl -0.0526902969 0.0000000000 1.4992485152 H 1.2597321349 1.2707785327 -0.5529086085 H 0.9809947174 0.0000000000 -2.4296895132 H 1.2597321349 -1.2707785327 -0.5529086085 6 F/Br Si-FSPostMIN F -1.0120183838 0.0000000000 -1.9405780080 Si 0.5888982829 0.0000000000 -1.8342771377 Br -0.0076671942 0.0000000000 1.1810112522 H 1.1614162548 1.2523054924 -1.3187687006 H 0.9510427779 0.0000000000 -3.2983809052 H 1.1614162548 -1.2523054924 -1.3187687006 6 F/I Si-FSPostMIN F -1.0098485132 0.0000000000 -2.6649178518 Si 0.5875397493 0.0000000000 -2.5554608987 I -0.0043078980 0.0000000000 1.0270202606 H 1.0877206577 1.2381340193 -1.9429678843 H 1.0299646712 0.0000000000 -3.9854024039 H 1.0877206577 -1.2381340193 -1.9429678843 6 Cl/Br Si-FSPostMIN Cl -0.8309061975 0.0000000000 -2.1350694764 Si 1.1224414931 0.0000000000 -1.4277753674 Br -0.0869165190 0.0000000000 1.5027432484 H 1.4757517323 1.2601532975 -0.7646550084 H 1.8888286966 0.0000000000 -2.7177615287 H 1.4757517323 -1.2601532975 -0.7646550084 6 Cl/I Si-FSPostMIN Cl -0.8560965543 0.0000000000 -2.8312720580 Si 1.1091077605 0.0000000000 -2.1784427531 I -0.0437466003 0.0000000000 1.3235684929 H 1.4088369176 1.2417854731 -1.4564970896 H 1.8979093753 0.0000000000 -3.4447719642 H 1.4088369176 -1.2417854731 -1.4564970896 6 Br/I Si-FSPostMIN Br -0.4644688851 0.0000000000 -2.4576895737 Si 1.5205322453 0.0000000000 -1.4222434476 I -0.0907364123 0.0000000000 1.8930113193 H 1.6907243919 1.2440896125 -0.6642657216 H 2.4948475395 0.0000000000 -2.5503826211 H 1.6907243919 -1.2440896125 -0.6642657216 6 F/Cl Si-WMIN F 0.0000000000 0.0000000000 -2.3474048348 Si 0.0000000000 0.0000000000 -0.6626641766 Cl -0.0000000000 0.0000000000 1.8260736369 H 1.4709087548 0.0000000000 -0.5065086086 H -0.7354543774 1.2738443483 -0.5065086086 H -0.7354543774 -1.2738443483 -0.5065086086 6 F/Br Si-WMIN F 0.0000000000 0.0000000000 -3.1562467411 Si 0.0000000000 0.0000000000 -1.4919477269 Br -0.0000000000 0.0000000000 1.3223840754 H 1.4550139743 0.0000000000 -1.2560376357 H -0.7275069872 1.2600790646 -1.2560376357 H -0.7275069872 -1.2600790646 -1.2560376357 6 F/I Si-WMIN F 0.0000000000 0.0000000000 -3.8122415983 Si 0.0000000000 0.0000000000 -2.1674744212 I -0.0000000000 0.0000000000 1.0944482638 H 1.4364839651 0.0000000000 -1.8487507914 H -0.7182419825 1.2440316059 -1.8487507914 H -0.7182419825 -1.2440316059 -1.8487507914 6 Cl/Br Si-WMIN Cl 0.0000000000 0.0000000000 -3.1406739064 Si 0.0000000000 0.0000000000 -0.8785223110 Br -0.0000000000 0.0000000000 1.7321853947 H 1.4667094266 0.0000000000 -0.7898920591 H -0.7333547133 1.2702076234 -0.7898920591 H -0.7333547133 -1.2702076234 -0.7898920591 6 Cl/I Si-WMIN Cl 0.0000000000 0.0000000000 -3.8124649956 Si 0.0000000000 0.0000000000 -1.6278662213 I -0.0000000000 0.0000000000 1.4587383398 H 1.4493340518 0.0000000000 -1.4018738751 H -0.7246670259 1.2551601075 -1.4018738751 H -0.7246670259 -1.2551601075 -1.4018738751 6 Br/I Si-WMIN Br 0.0000000000 0.0000000000 -3.1766538614 Si 0.0000000000 0.0000000000 -0.7675700439 I -0.0000000000 0.0000000000 2.1848697751 H 1.4590479135 0.0000000000 -0.6239902332 H -0.7295239567 1.2635725584 -0.6239902332 H -0.7295239567 -1.2635725584 -0.6239902332