Mild Aliphatic and Benzylic hydrocarbon C H Bond Chlorination Using Trichloroisocyanuric Acid (TCCA)

Mild Aliphatic and Benzylic hydrocarbon C H Bond Chlorination Using Trichloroisocyanuric Acid (TCCA) Sascha H. Combe, Abolfazl Hosseini, Alejandro Parra, # and Peter R. Schreiner*, Institute of Organic Chemistry, Justus-Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany; prs@org.chemie.uni-giessen.de # Departamento de Química Orgánica, Universidad Autónoma de Madrid Cantoblanco, 28049 Madrid, Spain Contents Spectral data... S2 Mechanistic studies - chain length... S18 Computations... S19 Computations at the B3LYP-D3/6-31G(d,p)/CPCM (solvent: CH2Cl2) level of theory... S19 Computations at the M06-2X/cc-pVTZ/CPCM (solvent: CH2Cl2) level of theory. S19 Literature... S32 S1

Spectral data S2

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Mechanistic studies - chain length Chain length = yield 13 / NHPI in mol% Average chain length = sum of chain length / sum of experiments Table S1. Radical chain length initiated by NHPI 1 h NHPI [equiv.] 13 [%] a Chain length Average chain length 0.1 27 3 1.2 (1.8) 0.2 31 1.5 0.3 31 1 0.4 32 0.8 0.5 31 0.6 0.6 31 0.5 3 h 0.1 35 3.5 1.5 (2.2) 0.2 37 1.9 0.3 38 1.3 0.4 37 0.9 0.5 42 0.8 0.6 33 0.5 Table S2. Radical chain length initiated by NHPI and CBr4 1 h NHPI [equiv.] CBr4 [equiv.] 13 [%] a Chain length Average chain length 0.1 0.1 32 3.2 (1.9) 0.2 0.2 29 1.45 0.3 0.3 32 1.06 3 h 0.1 0.1 42 4.2 (2.6) 0.2 0.2 40 2 0.3 0.3 43 1.4 a Yield determined by 1 H-NMR with dimethylterephthalate as internal standard. S18

Computations Computations at the B3LYP-D3/6-31G(d,p)/CPCM (solvent: CH2Cl2) level of theory All computations based on Kohn-Sham density functional theory (DFT) 1 were performed with the program package Gaussian09. 2 Geometry optimizations were performed with the B3LYP functional combination. 3 Empirical dispersion corrections by Grimme (D3-BJ) 4 were used to treat non-covalent interactions. Frequency analyses were performed to confirm that the optimized structures are local minima or transition states, and also to obtain the thermodynamic corrections to Gibbs free energies. For copper we utilized a cc-pvdz-dk all-electron basis set, 5 while for all other atoms a 6-31G(d,p) basis set was employed. Intrinsic reaction coordinate (IRC) calculations were performed to ensure that the obtained transition states do connect the reactants and products. Solution-phase (CPCM) single-point energy calculations were conducted on the basis of the gas phase optimized structures using dichloromethane as solvent at 298 K and 1 atm. Computations at the M06-2X/cc-pVTZ/CPCM (solvent: CH2Cl2) level of theory All structures were optimized at the M06-2X/cc-pVTZ/CPCM (solvent: CH2Cl2) level of theory 6 utilizing the Gaussian09 2 program package. The computed structures were characterized as minima on the potential energy hypersurface by vibrational frequency computations (with minima having only real frequencies) that also provided thermal corrections and zero-point vibrational energies (ZPVEs). Table S3. Absolute energies in au at the B3LYP-D3/6-31G(d,p)/CPCM (solvent: CH2Cl2) level of theory Structure HF ZPVE H298 G298 1 (NHPI) 588.2781303 74.8474635 588.148539 588.193585 2 (PINO) 587.6444517 67.3160932 587.527463 587.571969 3 (PhMe) 271.5886858 80.3187198 271.453549 271.491286 24 (Bn ) 270.9356121 72.0462606 270.814199 270.849807 27 (CA) 506.158332 50.6312402 506.069693 506.109473 cyanuric acid 505.4561936 41.0347358 505.382637 505.424047 monochloroisocyanuric acid monochloroisocyanuric acid 965.6929008 43.8654316 965.613758 965.657067 964.9920761 34.3787414 964.927917 964.972495 S19

Structure HF ZPVE H298 G298 Cu(OAc)2 2090.123867 64.3460902 2090.009214 2090.062015 CuOAc 1861.587239 31.5003548 1861.530757 1861.566982 AcOH 229.1001393 38.7794663 229.032850 229.065434 H 0.5002806 0.000000 0.497920 0.510935 2 + 3 859.2331375 147.634905 858.981012 589.063225 A 859.2497447 148.424848 858.995483 859.060223 TS1 859.2213378 0.231305 858.973552 859.034598 1 + 24 859.2315604 147.639833 858.978463 859.044342 23 + 24 2115.692914 0.0921 2155.511090 2155.596977 B 2155.710948 103.261726 2155.526966 2155.597519 TS2 2155.709060 0.166442 2155.524221 2155.590844 4a + 25 2155.720832 103.400406 2155.53628 2155.609703 3 + 25 1696.115111 108.019571 1695.925164 1696.011128 C 1696.147017 0.174276 1695.954584 1696.020766 TS3 1696.088086 0.167698 1695.903249 1695.967967 TS3 1696.088086 0.167698 1695.903249 1695.967967 24 + 28 1696.155152 0.174597 1695.962439 1696.029500 24 + 29 1696.178122 0.175092 1695.984838 1696.052742 24 + CBr4 10595.85245 77.0318725 10595.71416 10595.77774 TS4 10595.84379 77.1040362 10595.70682 10595.76739 5 + Br3C 10595.86906 78.7506224 10595.72831 10595.79260 3 + Br3C 8024.758913 84.1955267 8024.610472 8024.670604 TS5 8024.639865 77.9543122 8024.502354 8024.558531 24 + CHBr3 8024.765082 83.7154815 8024.617717 8024.677652 S20

Table S4. Energies of the reactions in kcal mol 1 at the B3LYP-D3/6-31G(d,p)/CPCM (solvent: CH2Cl2) level of theory Reaction ΔH298 ΔG298 1 2 + H 77.3 69.5 Cu(OAc)2 + H CuOAc + AcOH +35.4 +37.3 1 + Cu(OAc)2 2 + CuOAc + AcOH 112.3 monochloroisocyanuric acid + 3 24 + monochloroisocyanuric acid cyanuric acid + 3 24 + 27 29.2 27.4 29.9 27.6 Scheme S1. Generation of benzyl radical 3 (energies in kcal mol 1 ) S21

Scheme S2. Generation of benzyl chloride 4a (energies in kcal mol 1 ) Scheme S3. Regeneration of benzyl radical 24 (energies in kcal mol -1 ) S22

Scheme S4. Reaction of benzyl radical with CBr4 (energies in kcal mol 1 ) Scheme S5. Regeneration of benzyl radical 24 (energies in kcal mol 1 ) S23

Cartesian coordinates of all computed structures at the the B3LYP-D3/6-31G(d,p)/CPCM (solvent: CH2Cl2) level of theory NHPI 1 (C2v) C 2.88546600 0.69999200 0.00020300 C 1.68447600 1.42435800 0.00294800 C 0.50290500 0.70017600 0.00144200 C 0.50290100-0.70017500 0.00144700 C 1.68446500-1.42436800 0.00297200 C 2.88546100-0.70001100 0.00022000 H 3.83095500 1.23255800-0.00248100 H 1.67503300 2.50892600 0.00389300 H 1.67501200-2.50893600 0.00393400 H 3.83094600-1.23258400-0.00245100 C -0.90714800 1.18164300 0.00460800 O -1.35144100 2.30982700-0.02784100 O -1.35146200-2.30980700-0.02786100 N -1.67024500 0.00000900 0.07158700 C -0.90715400-1.18162900 0.00459000 O -3.03344700-0.00000200-0.11801800 H -3.41765200-0.00008600 0.77517600 PINO 2 (C2v) C -0.00000100 2.83541300 0.70128800 C -0.00000100 1.63735600 1.42504700 C -0.00000100 0.45154900 0.70257800 C -0.00000100 0.45154900-0.70257800 C -0.00000100 1.63735600-1.42504700 C -0.00000100 2.83541300-0.70128800 H -0.00000100 3.78120300 1.23275900 H -0.00000100 1.62786300 2.50926200 H -0.00000100 1.62786300-2.50926200 H -0.00000100 3.78120300-1.23275900 C -0.00000100-0.93725200 1.20220800 O 0.00000100-1.38705400 2.32196800 O 0.00000100-1.38705400-2.32196800 N -0.00000300-1.75640000 0.00000000 C -0.00000100-0.93725200-1.20220800 O 0.00000500-3.02190700 0.00000000 PhMe 3 (Cs) C -0.19499000 1.20330000-0.00923900 C 1.20127400 1.20618700 0.00221900 C 1.90563000 0.00000000 0.00863900 C 1.20127200-1.20618700 0.00221500 C -0.19499100-1.20330000-0.00924100 C -0.91452400 0.00000100-0.01237600 H -0.73528100 2.14686200-0.01776000 H 1.73854700 2.15049600 0.00203000 H 2.99168500-0.00000100 0.01439800 H 1.73854500-2.15049700 0.00203700 H -0.73528100-2.14686200-0.01774600 C -2.42517800-0.00000100 0.00932300 H -2.83307800-0.88639400-0.48564700 H -2.80301600 0.00012700 1.03931300 H -2.83308000 0.88627300-0.48586100 BnCl 4a (Cs) C 2.65716700-0.00009300-0.36725700 C 1.98862900-1.20961600-0.16059100 C 0.65563200-1.20892200 0.25000400 C -0.02109700 0.00008300 0.46009100 C 0.65574700 1.20899800 0.24986200 C 1.98874800 1.20951800-0.16072800 H 3.69535700-0.00016100-0.68548300 H 2.50560800-2.15153400-0.31698100 H 0.13491900-2.14925700 0.40969400 H 0.13512300 2.14939900 0.40944500 H 2.50581800 2.15136900-0.31722000 C -1.45211600 0.00017900 0.89643000 H -1.71652200-0.89145500 1.46395800 H -1.71649900 0.89202600 1.46363500 Cl -2.61059200-0.00007400-0.55493600 BnBr 5 (Cs) C 3.21968000 0.00005900-0.49243100 C 2.57272300-1.20962200-0.22549300 C 1.28359900-1.20939000 0.30598000 C 0.62994200-0.00005500 0.58091400 C 1.28353900 1.20934000 0.30608100 C 2.57265200 1.20968800-0.22540100 H 4.22392300 0.00010400-0.90538800 H 3.07268700-2.15146800-0.43021500 H 0.77824100-2.14940400 0.51025400 H 0.77812400 2.14930400 0.51041800 H 3.07255400 2.15157900-0.43006800 C -0.74681200-0.00010100 1.15124900 H -0.97702700-0.89514800 1.72560900 H -0.97707500 0.89481000 1.72580700 Br -2.13895300 0.00002000-0.31748000 TCCA 23 (C3) S24

C -1.18605700-0.84821400-0.00005400 O -2.16525700-1.54825800-0.00011500 N -1.22686500 0.55701900 0.00007900 N 0.13070200-1.34098900-0.00009800 C -0.14167600 1.45067600 0.00011800 C 1.32726400-0.60274000-0.00007100 O 2.42313600-1.10067200-0.00014300 O -0.25867400 2.64869100 0.00019800 N 1.09610000 0.78391000 0.00005800 Cl 0.29761700-3.04836100-0.00022600 Cl -2.78865800 1.26682100 0.00013500 Cl 2.49160700 1.78177500 0.00010500 Bn 24 (C2v) C 0.00000000 0.00000000-1.84028400 C 0.00000000 1.21277100-1.13408900 C 0.00000000 1.21948100 0.25247600 C 0.00000000 0.00000000 0.99551200 C 0.00000000-1.21948100 0.25247600 C 0.00000000-1.21277100-1.13408900 H 0.00000000 0.00000000-2.92584200 H 0.00000000 2.15372800-1.67700200 H 0.00000000 2.16193000 0.79358900 H 0.00000000-2.16193000 0.79358900 H 0.00000000-2.15372800-1.67700200 C 0.00000000 0.00000000 2.40259200 H -0.00000100 0.92897700 2.96255000 H 0.00000100-0.92897700 2.96255000 dichloroisocyanuric acid 25(Cs) C 1.21141900 1.25410700 0.03683100 O 2.21550000 1.90030700-0.17206900 N 1.17136000-0.15085700 0.04749500 N -0.00006100 1.87015100 0.35696600 C 0.00004800-0.93866300 0.06942600 C -1.21155900 1.25417100 0.03626000 O -2.21563700 1.90019400-0.17288000 O 0.00003900-2.14077500 0.07984100 N -1.17132300-0.15086700 0.04746200 Cl 2.66325000-0.99037300-0.05602200 Cl -2.66316100-0.99047900-0.05560700 dichloroisocyanuric acid 26 (C2v) C -1.24649200 1.23641900-0.00000500 O -2.28478600 1.85447500 0.00000300 N -1.16942600-0.17134500-0.00002500 N 0.00000000 1.83605500 0.00001900 C 0.00000000-0.95484600-0.00000100 C 1.24649200 1.23641900-0.00000500 O 2.28478600 1.85447500 0.00000400 O 0.00000100-2.15968900 0.00002600 N 1.16942600-0.17134500-0.00002600 Cl -2.65660200-1.02367600 0.00000000 Cl 2.65660100-1.02367600-0.00000100 H 0.00000000 2.84937600 0.00002800 Br3C (C3v) C 0.00011100-0.00004900 0.34697700 Br 0.10512200 1.85923200-0.01982600 Br -1.66279800-0.83857300-0.01982600 Br 1.55765700-1.02065100-0.01983000 CBr4 (D2d) C -0.00000200-0.00008400 0.00000900 Br 0.55473500 1.20857600-1.44160700 Br -1.33924100 0.89174700 1.12162400 Br -0.77403800-1.62791600-0.77301900 Br 1.55854400-0.47239300 1.09300000 cyanuric acid 27 (Cs) C -0.97997700-1.04437900-0.00001500 O -1.81124700-1.93102500-0.00002800 N 0.38778400-1.28213300 0.00024200 N -1.30444700 0.30531100-0.00012000 C 1.39457900-0.32637700-0.00000600 C -0.41465000 1.37075400-0.00000300 O -0.76656600 2.53408300 0.00000600 O 2.57804100-0.60315400-0.00019900 N 0.91652100 0.97692000 0.00017900 H -2.28968300 0.53610900-0.00031000 H 0.68021400-2.25091900 0.00010300 H 1.60891700 1.71491000 0.00001100 cyanuric acid (C1) C -1.40997000 0.00439500-0.01117100 O -2.62275300 0.00810200 0.00998300 N -0.64689600-1.15745000-0.01302000 N -0.63966800 1.16148900-0.01271600 C 0.73714900-1.21060400-0.02245900 C 0.74471900 1.20599700-0.02245900 O 1.37816300 2.23703500 0.13753200 O 1.36412200-2.24555800 0.13770300 N 1.41570900-0.00440700-0.27008200 H -1.13944800 2.04016400 0.06290400 H -1.15220300-2.03294800 0.06261700 S25

HCBr3 (Cs) C 0.00029700-0.00000800 0.54416700 Br -0.90880000 1.62637900-0.04659600 Br -0.95438600-1.60006300-0.04659700 Br 1.86311800-0.02631400-0.04662700 H 0.00056000-0.00002000 1.62869500 monochloroisocyanuric acid (C2v) C -2.03607600-0.00000200 0.00000300 O -3.24971600 0.00000200 0.00002000 N -1.27229400-1.15800400-0.00000700 N -1.27229300 1.15800200-0.00002200 C 0.10855400-1.25877000 0.00004400 C 0.10855300 1.25877200-0.00004900 O 0.70116200 2.31335400-0.00010700 O 0.70116200-2.31335300 0.00010200 N 0.74735300 0.00000100 0.00000900 H -1.77796400 2.03544200-0.00003300 H -1.77795400-2.03545000 0.00004800 Cl 2.46055900 0.00000000 0.00000100 monochloroisocyanuric acid (C1) C -0.08141600 1.24873700-0.01525800 O -0.67107300 2.30173600 0.00414600 N -0.72613000-0.01318100-0.05272600 N 1.29901300 1.13632600 0.02292500 C -0.07071700-1.25969300-0.02522500 C 2.02046100-0.04391100-0.02423400 O 3.22705900-0.09594300 0.14347600 O -0.63803500-2.31335500 0.17297500 N 1.29597300-1.20712600-0.31980100 H 1.81384600 2.00349400 0.13208000 Cl -2.43820100-0.01329000 0.00815700 Complex A C 0.14717600 2.56861100-0.32765300 C 1.26928600 1.95401200-0.88890200 C 2.12287800 1.15904400-0.11142800 C 1.81888700 0.99598300 1.24939900 C 0.69954900 1.60834800 1.81482300 C -0.14211400 2.39835500 1.02686200 H -0.50449500 3.17299100-0.95164400 H 0.47954500 1.45975300 2.86790700 H -1.01898000 2.86682900 1.46279100 C -1.09210700-0.63461200-0.88943700 C -1.36196700-0.80752900 0.47715100 C -2.51893100-0.30126800 1.05475000 C -3.40832500 0.38764500 0.22407800 C -3.13807500 0.56120200-1.14190200 C -1.97085600 0.05026900-1.71835500 C 0.20267500-1.25631400-1.22456400 C -0.25703600-1.54801800 1.11549600 H -2.71503700-0.43419800 2.11273800 H -4.32169400 0.79833300 0.64150100 H -3.84681700 1.10317700-1.75919000 H -1.75002900 0.18460700-2.77124700 O -0.08052200-1.90310000 2.25517400 O 0.81237300-1.33740100-2.26376500 N 0.67666500-1.81119900 0.03198000 O 1.77699500-2.42017300 0.17155000 H 2.46044200 0.37218400 1.86630900 H 1.48268400 2.08529400-1.94646400 C 3.30925400 0.45702400-0.72573800 H 3.64398600 0.96055900-1.63698500 H 4.15052300 0.41201500-0.02761300 H 3.05068100-0.57427800-0.99311800 Complex B C -2.29476500 0.16611100 1.96575100 C -1.56921400-1.01846800 2.16543800 C -0.19522400-0.97893100 2.35160400 C 0.51415400 0.26102000 2.34510300 C -0.24831200 1.45134400 2.13802200 C -1.62166400 1.39762500 1.95315900 H -3.36769400 0.12913300 1.81017700 H -2.08405500-1.97422100 2.16227500 H 0.36199500-1.90006500 2.49671400 H 0.26767500 2.40697600 2.11668800 H -2.17738500 2.31502200 1.78505400 C 1.91003400 0.30585100 2.51391600 H 2.48623400-0.60222300 2.64996800 H 2.44493900 1.24861300 2.49657200 C -0.09257700 1.31800400-1.11815400 O -0.34085800 2.49070300-1.22871700 N 1.19803900 0.80825200-0.89376300 N -1.05521800 0.29990100-1.22072900 C 1.57432300-0.53351900-0.71669300 C -0.86743600-1.08133700-1.04877800 O -1.75468700-1.89279300-1.10565000 O 2.70370000-0.89355100-0.50607500 N 0.47992600-1.40873700-0.81864700 Cl -2.66385100 0.81132800-1.51721300 Cl 2.44799200 1.96971400-0.73101200 Cl 0.81514700-3.06811400-0.54931300 TS2 S26

C 0.08076500-1.21448300 2.43238700 C 1.29689500-1.21735800 1.75646800 C 1.91471400-0.00002200 1.40999400 C 1.29684600 1.21727300 1.75652600 C 0.08071500 1.21431500 2.43244500 C -0.52958000-0.00010400 2.76548500 H -0.39963500-2.15290700 2.68682100 H -0.39972300 2.15270700 2.68692400 H -1.48627700-0.00013600 3.27764200 H 1.76047500-2.15508600 1.46770100 H 1.76038700 2.15503300 1.46780200 C 3.17044900 0.00002000 0.67091200 H 3.75926000-0.91138100 0.70450100 H 3.75922500 0.91144200 0.70454400 Cl 2.77932000 0.00006200-1.39234200 N 0.72945500 0.00004600-1.41586900 N -1.18298300 1.16107000-0.71916300 N -1.18296200-1.16104200-0.71921400 Cl -1.95902400 2.65318700-0.34678000 Cl -1.95897700-2.65319000-0.34689800 C -1.89933400 0.00000000-0.39654200 C 0.16505000 1.22912400-1.17313300 C 0.16506900-1.22905300-1.17319400 O -3.00700000-0.00002000 0.08695200 O 0.72912700-2.29251700-1.32115700 O 0.72909200 2.29260400-1.32103900 Cl 0.81514700-3.06811400-0.54931300 Complex C C 1.10333600-1.01170600-1.11241000 O 1.48590000-2.12715600-1.42967300 N 1.88862400-0.20506600-0.23774400 N -0.08650700-0.48006500-1.53170600 C 1.55930000 1.07890900 0.22448200 C -0.50050300 0.76322500-1.18125700 O -1.56291500 1.24708000-1.56615200 O 2.24297400 1.72376700 0.98556600 N 0.33926000 1.51262400-0.30505400 Cl 3.38296000-0.84813600 0.32677300 Cl -0.19151200 3.07231100 0.19342000 C -1.49926200-0.43362300 1.60838300 C -2.52907000 0.41167800 1.23555300 C -3.39113100 0.05799000 0.16737400 C -3.21523300-1.15227500-0.51074800 C -2.16857200-1.98611100-0.15605600 C -1.29695200-1.65351500 0.92778000 H -0.83915900-0.16621900 2.42704300 H -2.67612200 1.35455500 1.75029900 H -4.19027900 0.73251000-0.11848700 H -3.87021500-1.41596700-1.33316200 H -1.99978000-2.91511900-0.69038400 C -0.23967900-2.62016500 1.35383000 H -0.70866300-3.50323400 1.80743200 H 0.33361800-2.98271700 0.49295100 H 0.44526400-2.18320400 2.08304900 TS3 C -4.26389000 0.96407100-0.25430200 C -4.68986100 0.25091200-1.35736100 C -4.19858200-1.04868000-1.58501100 C -3.27613800-1.63125300-0.69815100 C -2.84217400-0.93090700 0.41134200 C -3.33496700 0.38699300 0.66543500 H -4.63218800 1.96822800-0.06876200 H -5.40125400 0.68844100-2.04954900 H -4.53200700-1.60335600-2.45637400 H -2.89837900-2.63003600-0.88912800 H -2.10426200-1.36047100 1.07893800 C -2.89456200 1.11857800 1.80293900 H -2.37147100 0.59390300 2.59713900 H -1.44399300 1.78952200 1.14068200 H -3.40665200 2.03774900 2.07478900 C 0.63565100 1.18178500 0.44911400 O 0.04178700 2.29663600 0.54260800 N 1.92567300 1.19387500-0.11088800 N 0.11132200 0.03579200 0.84487500 C 2.71045400 0.04203500-0.31480100 C 0.73165500-1.16091500 0.69780800 O 0.25452100-2.23611200 1.02089800 O 3.81728300 0.06557800-0.80318200 N 2.04657700-1.10897700 0.11137600 Cl 2.62072200 2.68822600-0.61967400 Cl 2.89874600-2.59254000-0.10561600 TS3 C -4.26826500-1.04959500 0.29820000 C -4.72934100-1.11580100-1.00293700 C -4.30192700-0.16585300-1.94811600 C -3.40738500 0.85622800-1.58377900 C -2.94073400 0.93684000-0.28556100 C -3.36832400-0.01420700 0.69131200 H -4.58799400-1.77822800 1.03648700 H -5.41930100-1.89901400-1.29809200 H -4.66336300-0.22523400-2.96977200 H -3.08261700 1.57861500-2.32503100 H -2.23108000 1.70184900 0.01115200 C -2.88874400 0.06671900 2.02666600 H -1.30211000-0.72334100 1.77667800 S27

H -2.37822400 0.96850600 2.35177700 H -3.31117200-0.57819300 2.79162800 C 0.56834700 0.91630100 0.89508700 O -0.17125600 1.81624200 1.26213800 N 1.73505100 1.20020300 0.12030100 N 0.39427800-0.39828600 1.17210300 C 2.64087600 0.25824700-0.39001400 C 1.11680800-1.44553900 0.69690100 O 0.86131400-2.61940100 0.88259300 O 3.61871300 0.54446700-1.04358000 N 2.27172400-1.05127100-0.05619900 Cl 2.06703500 2.84850600-0.24628100 Cl 3.29593300-2.30085900-0.64924900 DCCA enol 28 (Cs) C -1.12452300 1.18076600-0.00001200 O -2.32069300 1.73625400-0.00001000 N -1.13815000-0.19525500-0.00000600 N -0.04219700 1.88997600-0.00001500 C 0.05708700-0.96027600-0.00001500 C 1.20002600 1.29893800 0.00000200 O 2.24833600 1.90305500 0.00004300 O 0.06474600-2.16559100 0.00000300 N 1.18404900-0.13886700-0.00004700 Cl -2.61577400-1.07703000 0.00001800 Cl 2.70052800-0.95235300 0.00000200 H -2.20138800 2.70221800 0.00000200 S28

Table S5. Absolute energies in au at the M06-2X/cc-pVTZ/CPCM (CH2Cl2) level of theory Structure HF ZPVE H298 G298 3 (PhMe) 271.5356996 0.128609 271.399953 271.437834 4a (BnCl) 731.1456823 0.120678 731.017194 731.057663 5 (BnBr) 2845.1817349 0.120067 2845.053694 2845.095427 23 (TCCA) 1884.8114462 0.050220 1884.749626 1884.798491 24 (Bn ) 270.883073 0.115325 270.761170 270.796733 25 (DCCA ) 1424.5404467 0.045318 1424.484395 1424.533086 26 (DCCA) 1425.2633908 0,060638 1425.192428 1425.238210 27 (CA) 506.1639071 0.081451 506.074627 506.114138 cyanuric acid 505.4558102 0.066770 505.381096 505.421653 monochloroisocyanuric acid monochloroisocyanuric acid 965.7142122 0.071010 965.634125 965.676469 965.0067293 0.056486 964.941087 964.985091 CBr4 10335.0367558 0.007224 10335.02186 0 10335.06326 Br3C 7760.7548642 0.005596 7760.743173 7760.781400 HCBr3 7761.4127451 0.018344 7761.388383 7761.426853 Table S6. Energies of the reactions in kcal mol 1 at the M06-2X/cc-pVTZ/CPCM (CH2Cl2) level of theory Reaction ΔH298 ΔG298 25 + 3 24 + 26 43.5 40.2 monochloroisocyanuric acid + 3 24 + 34.1 31.6 monochloroisocyanuric acid cyanuric acid + 3 24 + 27 34.4 32.2 24 + CBr4 Br3C + 5 3 + Br3C HCBr3 + 24 23 + 24 4a + 25 8.68 10.6 4.03 2.73 5.78 2.81 S29

Cartesian coordinates of all computed structures at the M06-2X/cc-pVTZ/CPCM (CH2Cl2) level of theory PhMe 3 (Cs) 6-0.004173000 0.908568000 0.000000000 6-0.007040000 0.194241000 1.196166000 6-0.007040000-1.194160000 1.199272000 6-0.006050000-1.894320000 0.000000000 6-0.007040000-1.194160000-1.199272000 6-0.007040000 0.194241000-1.196166000 6 0.026592000 2.412260000 0.000000000 1-0.012239000 0.733884000 2.135415000 1-0.011466000-1.729544000 2.139402000 1-0.008918000-2.975787000 0.000000000 1-0.011466000-1.729544000-2.139402000 1-0.012239000 0.733884000-2.135415000 1 1.055746000 2.776054000 0.000000000 1-0.464331000 2.815510000-0.884325000 1-0.464331000 2.815510000 0.884325000 BnCl 4a (Cs) 6 0.429400000-0.162959000 0.000000000 6 0.429151000 0.539385000 1.201429000 6 0.429151000 1.926720000 1.202465000 6 0.428564000 2.622163000 0.000000000 6 0.429151000 1.926720000-1.202465000 6 0.429151000 0.539385000-1.201429000 6 0.415966000-1.656639000 0.000000000 1 0.429402000-0.005359000 2.137449000 1 0.432414000 2.464971000 2.140376000 1 0.430742000 3.703578000 0.000000000 1 0.432414000 2.464971000-2.140376000 1 0.429402000-0.005359000-2.137449000 1 0.880247000-2.070108000 0.888922000 17-1.285769000-2.287720000 0.000000000 1 0.880247000-2.070108000-0.888922000 BnBr 5 (Cs) 6-0.758608000 0.357723000 0.000000000 6-0.758057000 1.060878000 1.201636000 6-0.758057000 2.447932000 1.202408000 6-0.757282000 3.143644000 0.000000000 6-0.758057000 2.447932000-1.202408000 6-0.758057000 1.060878000-1.201636000 6-0.758094000-1.132134000 0.000000000 1-0.757810000 0.516293000 2.137782000 1-0.761280000 2.986009000 2.140408000 1-0.758952000 4.225027000 0.000000000 1-0.761280000 2.986009000-2.140408000 1-0.757810000 0.516293000-2.137782000 35 1.087382000-1.841406000 0.000000000 1-1.211986000-1.550775000-0.890656000 1-1.211986000-1.550775000 0.890656000 TCCA 23 (C3) 17-2.620266000 1.512856000-0.000010000 7-1.160985000 0.670284000-0.000001000 6 0.000000000 1.442136000 0.000000000 7 1.160976000 0.670300000-0.000001000 6 1.248926000-0.721068000 0.000000000 7 0.000009000-1.340584000-0.000001000 6-1.248926000-0.721068000 0.000000000 8-2.281750000-1.317375000 0.000021000 17-0.000039000-3.025645000-0.000010000 8 2.281755000-1.317366000 0.000021000 17 2.620304000 1.512789000-0.000010000 8-0.000005000 2.634741000 0.000021000 Bn 24 (C2v) 6 0.000000000 0.000000000 0.985453000 6 0.000000000 1.210927000 0.251533000 6 0.000000000 1.205250000-1.127964000 6 0.000000000 0.000000000-1.829265000 6 0.000000000-1.205250000-1.127964000 6 0.000000000-1.210927000 0.251533000 6 0.000000000 0.000000000 2.391966000 1 0.000000000 2.148674000 0.792659000 1 0.000000000 2.142355000-1.668421000 1 0.000000000 0.000000000-2.910296000 1 0.000000000-2.142355000-1.668421000 1 0.000000000-2.148674000 0.792659000 1 0.000000000 0.927378000 2.945038000 1 0.000000000-0.927378000 2.945038000 dichloroisocyanuric acid 25(Cs) 7-1.172188000 0.141670000 0.000000000 6-1.143229000-1.481995000 0.000000000 6 1.205791000-1.237315000 0.000000000 7 1.120779000 0.223844000 0.000000000 6 0.000000000 0.993418000 0.000000000 8-2.238053000-1.943030000 0.000000000 8 2.308190000-1.708427000 0.000000000 S30

8-0.082571000 2.181838000 0.000000000 17 2.574133000 1.076763000 0.000000000 17-2.595078000 0.876762000 0.000000000 7 0.062863000-1.950888000 0.000000000 dichloroisocyanuric acid 26 (C2v) 7 0.000000000 0.000000000-1.826028000 6 0.000000000 1.235317000-1.222778000 7 0.000000000 1.163070000 0.172718000 6 0.000000000 0.000000000 0.943802000 7 0.000000000-1.163070000 0.172718000 6 0.000000000-1.235317000-1.222778000 8 0.000000000-2.267606000-1.829458000 17 0.000000000-2.623187000 1.011279000 8 0.000000000 0.000000000 2.137513000 17 0.000000000 2.623187000 1.011279000 8 0.000000000 2.267606000-1.829458000 1 0.000000000 0.000000000-2.837591000 Br3C (C3v) 6 0.000000000 0.000000000 0.270935000 35 0.000000000 1.845454000-0.015482000 35 1.598210000-0.922727000-0.015482000 35-1.598210000-0.922727000-0.015482000 CBr4 (D2d) 6 0.000000000 0.000000000 0.000000000 35 0.000000000 1.583020000 1.118376000 35 0.000000000-1.583020000 1.118376000 35-1.583020000 0.000000000-1.118376000 35 1.583020000 0.000000000-1.118376000 cyanuric acid 27 (Cs) 7 0.000000000 1.333242000 0.000000000 6 1.229742000 0.709926000 0.000000000 8 2.272715000 1.312293000 0.000000000 7 1.154753000-0.666687000 0.000000000 6-0.000003000-1.419984000 0.000000000 8-0.000001000-2.624387000 0.000000000 7-1.154752000-0.666685000 0.000000000 6-1.229738000 0.709935000 0.000000000 8-2.272715000 1.312295000 0.000000000 1 0.000008000 2.343444000 0.000000000 1 2.029735000-1.171706000 0.000000000 1-2.029738000-1.171698000 0.000000000 6 0.735514000 1.208648000 0.027525000 8 1.378842000 2.196273000-0.197951000 7 1.355779000 0.000000000 0.406049000 6 0.735513000-1.208648000 0.027525000 8 1.378842000-2.196274000-0.197951000 7-0.639633000-1.158901000 0.015193000 6-1.395240000 0.000000000 0.015183000 8-2.595607000 0.000001000-0.015504000 1-1.143465000 2.029859000-0.092602000 1-1.143466000-2.029859000-0.092603000 HCBr3 (Cs) 6 0.449171000 0.279835000 0.000000000 35-1.014314000 1.536134000 0.000000000 1 1.363972000 0.852293000 0.000000000 35 0.449171000-0.804229000 1.594531000 35 0.449171000-0.804229000-1.594531000 monochloroisocyanuric acid (C2v) 7 0.000000000 0.000000000 0.746658000 6 0.000000000 1.245281000 0.109740000 8 0.000000000 2.287140000 0.702374000 7 0.000000000 1.152831000-1.262830000 6 0.000000000 0.000000000-2.017483000 8 0.000000000 0.000000000-3.220352000 7 0.000000000-1.152831000-1.262830000 6 0.000000000-1.245281000 0.109740000 8 0.000000000-2.287140000 0.702374000 17 0.000000000 0.000000000 2.429487000 1 0.000000000-2.028685000-1.767710000 1 0.000000000 2.028685000-1.767710000 monochloroisocyanuric acid (C1) 7-0.729272000-0.015298000 0.064723000 6-0.078657000-1.248188000 0.047719000 8-0.618439000-2.291152000-0.175573000 7 1.275666000-1.169501000 0.407609000 6 2.015050000-0.036764000 0.014036000 8 3.188493000-0.109794000-0.220249000 7 1.291261000 1.132852000-0.005235000 6-0.084388000 1.232758000 0.036214000 8-0.673223000 2.272389000 0.017248000 17-2.408705000-0.017385000-0.041135000 1 1.797732000 2.000802000-0.129610000 cyanuric acid (C1) 7-0.639632000 1.158901000 0.015194000 S31

Literature (1) Calais, J.-L. Int. J. Quantum Chem. 1993, 47, 101. (2) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery Jr., J. A.; Peralta, J. E.; Ogliaro, F.; Bearpark, M. J.; Heyd, J.; Brothers, E. N.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A. P.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, N. J.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, Ö.; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J.; Gaussian, Inc.: Wallingford, CT, USA, 2009. (3) (a) Becke, A. D. J. Chem. Phys. 1993, 98, 5648; (b) Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. B 1988, 37, 785. (4) (a) Grimme, S.; Antony, J.; Ehrlich, S.; Krieg, H. J. Chem. Phys. 2010, 132, 154104; (b) Grimme, S.; Ehrlich, S.; Goerigk, L. J. Comput. Chem. 2011, 32, 1456. (5) (a) Dunning Jr., T. H. J. Chem. Phys. 1989, 90, 1007; (b) Balabanov, N. B.; Peterson, K. A. J. Chem. Phys. 2005, 123, 064107. (6) (a) Zhao, Y.; Truhlar, D. G. Theor. Chem. Account 2007, 120, 215; (b) Zhao, Y.; Truhlar, D. G. Acc. Chem. Res. 2008, 41, 157. S32