* To whom correspondence should be addressed.

Transcript

1 SUPPORTING INFORMATION Computational design of a pincer phosphinito vanadium ((OPO)V) propane monoxygenation homogeneous catalyst based on the reduction-coupled oxo activation (ROA) mechanism Ross Fu, William A. Goddard III,* Mu-Jeng Cheng, and Robert J. Nielsen Materials and Process Simulation Center (139-74) California Institute of Technology, Pasadena, CA USA. * To whom correspondence should be addressed. wag@wag.caltech.edu TABLE OF CONTENTS A. Reformation of starting V V species from V V peroxide and V III via protonation/oxidation 2 B. Tables of (OPO)V species studied..5 C. Suggestions for the experimental synthesis of (OPO)V species...23 D. References.25

2 A. Reformation of starting V V species from V V peroxide and V III via protonation/oxidation One possibility for how a (OPO)V V (O2) peroxide species, such as (OPO) f V V (HOiPr) t (O2) s (H2O) c (278) or (OPO) f V V (η 2 -O2) c (H2O)2 st (409), might be converted back to the starting V V species 6 is via the direct protonation of the peroxide ligand off, releasing H2O2. If the peroxide 278 is protonated, a (OPO)V V (OiPr) species will be produced, which can then lose HOiPr to form the starting species 6 (Scheme S1). Species involved in the protonation of the peroxide ligand in (OPO)V V (O2)(OiPr) are listed in Table S6, and the resulting (OPO)V V (OiPr) species are listed in Table S9. The lowest energy (OPO)V V (OiPr) species is five-coordinate (OPO)V V O s (HOiPr) a (459), but the six-coordinate species (OPO) f HV V O s (OiPr) c (H2O) t (477) is only 1.0 kcal/mol higher in energy. Scheme S1. The lowest energy (OPO)V V (O2) peroxide species, (OPO) f V V (η 2 -O2) c (H2O)2 st (409), can isomerize to form a (OPO)V V (HOOH) species and then lose H2O2 to form 6. All ΔGrel values are in kcal/mol and relative to 6 at the beginning of the reaction. Note that 6 in this scheme is at 12.9 because ΔG = 12.9 kcal/mol for the reaction iprh + O2 + H2O iproh + H2O2. By contrast, if the peroxide 409 is protonated off, the starting species 6 is formed directly (Scheme S2). Species involved in the protonation of 409 are listed in Table S7, and the lowest energy pathway for such a process goes through (OPO) f HV V O s (HOOH) c (OH) t (441), the lowest energy (OPO)V V (HOOH) species. Scheme S2. The lowest energy (OPO)V V (O2) peroxide species, (OPO) f V V (η 2 -O2) c (H2O)2 st (409), can isomerize to form a (OPO)V V (HOOH) species and then lose H2O2 to form 6. All ΔGrel values are in kcal/mol and relative to 6 at the beginning of the reaction. Note that 6 in this scheme is at 12.9 because ΔG = 12.9 kcal/mol for the reaction iprh + O2 + H2O iproh + H2O2.

3 By comparing Schemes S1 and S2, we see that it is more favorable for 409 to have its peroxide protonated off as in Scheme S2. The highest energy species in this pathway is 441 at 9.8 kcal/mol relative to the starting complex 6. By contrast, species 369 in Scheme S1 is at 9.5 kcal/mol, and 461 may be even higher in energy as we were unable to find its optimized structure. We thus conclude that it is most likely for 278 to first lose its isopropanol ligand to form 409 before seeing its peroxide ligand protonated off, and this is reflected in the first row of our Scheme 7. The H2O2 released in Schemes S1 and S2 can then coordinate with another equivalent of (OPO)V III to form a (OPO)V III (HOOH) species, which can be intramolecularly converted a second (OPO)V V species. We note that there are two types of (OPO)V III species: (OPO)V III (OiPr) species, which contain an isoproxo ligand ( , Table S4), and (OPO)V III species that only contain hydroxo/aqua ligands ( , Table S5). If H2O2 coordinates with a (OPO)V III (OiPr) species, a (OPO)V III (OiPr)(H2O2) species ( , Table S10) is then formed. The lowest energy isomer is six-coordinate 3 [(OPO) f HV III (HOiPr) s (OOH) c (H2O) t ] (503), and H2O/H2O2 ligand exchange from 168 to 503 is downhill in free energy by 2.2 kcal/mol. This can then convert to (OPO)V V O s (HOiPr) a (459) via a V V-III transition state ( , Table S11). The lowest such transition state found is 3 [(OPO)HV(HOiPr) a (O OH) s ] (516). Note that triplet transition states were found to be lower in energy than singlet transition states with broken-symmetry correction; this is likely due to the extreme early-state nature of the transition states. Finally, (OPO)V V O s (HOiPr) a (459) can exchange HOiPr for an aqua ligand to regenerate the starting complex 6. The overall process for this oxidation is shown in Scheme S3. Scheme S3. Hydrogen peroxide released at the end of schemes S1 and S2 can oxidize a (OPO)V III (OiPr) species such as 168 to form an (OPO)V V (OiPr) species such as 459, which can release HOiPr and bind to an aqua ligand (see Scheme S1 for details) to reform the starting species 6. All ΔGrel values are in kcal/mol and relative to 6 at the beginning of the reaction. Note that 6 in this scheme is at 69.9 kcal/mol as it represents the second equivalent of 6 produced;

4 the first equivalent is at 12.9 kcal/mol (Schemes S1 and S2) and their sum, 82.9 kcal/mol, is the free energy change for the reaction 2iPrH + O2 2iPrOH. If H2O2 instead coordinates with a (OPO)V III species with only oxo/hydroxo/aqua ligands, a (OPO)V III (H2O2) species ( , Table S12) is then formed. The lowest energy isomer is sixcoordinate 3 [(OPO) f HV III (OOH) c (H2O)2 st ] (538). This can then convert to the starting (OPO)V V species 6 via a V V-III transition state ( , Table S13). The lowest such transition state found is 3 [(OPO)HV(O OH) s (H2O) a ] (542). Note that, as in the OiPr case, triplet transition states were found to be lower in energy than singlet transition states with broken-symmetry correction. The overall process for this oxidation is shown in Scheme S4. Scheme S4. Hydrogen peroxide released at the end of schemes S1 and S2 can oxidize a (OPO)V III species such as 200 to reform the starting species 6. All ΔGrel values are in kcal/mol and relative to 6 at the beginning of the reaction. Note that 6 in this scheme is at 69.9 kcal/mol as it represents the second equivalent of 6 produced; the first equivalent is at 12.9 kcal/mol (Schemes S1 and S2) and their sum, 82.9 kcal/mol, is the free energy change for the reaction 2iPrH + O2 2iPrOH. By comparing Schemes S3 and S4, we see that 516 in Scheme S3 is the lower-energy transition state. Hence we conclude that the released H2O2 first oxidizes a (OPO)V III (OiPr) species such as 168 to form 459 before seeing its isopropanol ligand replaced with an aqua, and this is reflected in the second and third rows of our Scheme 7.

5 B. Tables of (OPO)V species studied Table S1a. Comprehensive compilation of all (OPO)V V species studied, along with their gasphase energies (Egas) and aqueous free energies (Gaq), both in hartrees; and their aqueous free energies relative to each other (ΔGrel), in kcal/mol. For some entries, geometry optimisation led to the formation of a lower-energy isomer. The energies for these entries are not reported. Entry Coord. Species Egas Gaq ΔGrel 1 5 (OPO)V V Cl (OPO)V V (OH) (OPO)V V =O (OPO)V V O s (H2O) a (OPO)V V O a (H2O) s (OPO)HV V O s (OH) a (OPO)HV V O a (OH) s geometry unstable N/A 8 5 [(OPO)HV V O s (H2O) a ] [(OPO)HV V O a (H2O) s ] + geometry unstable N/A 10 5 [(OPO)V V O s (OH) a ] [(OPO)V V O a (OH) s ] [(OPO)V V O2] (OPO) f V V O c (H2O)2 st (OPO) f V V O s (H2O)2 ct (OPO) f V V O t (H2O)2 cs (OPO) f HV V O c (OH) s (H2O) t (OPO) f HV V O c (OH) t (H2O) s (OPO) f HV V O s (OH) c (H2O) t (OPO) f HV V O s (OH) t (H2O) c (OPO) f HV V O t (OH) c (H2O) s (OPO) f HV V O t (OH) s (H2O) c [(OPO) f HV V O c (OH)2 st ] [(OPO) f HV V O s (OH)2 ct ] [(OPO) f HV V O t (OH)2 cs ] [(OPO) f V V O c (OH) s (H2O) t ] [(OPO) f V V O c (OH) t (H2O) s ] [(OPO) f V V O s (OH) c (H2O) t ] [(OPO) f V V O s (OH) t (H2O) c ] [(OPO) f V V O t (OH) c (H2O) s ] [(OPO) f V V O t (OH) s (H2O) c ] [(OPO) f V V O c (OH)2 st ] [(OPO) f V V O s (OH)2 ct ]

6 Table S1b. Continuation from Table S1a. Entry Coord. Species Egas Gaq ΔGrel 33 6 [(OPO) f V V O t (OH)2 cs ] [(OPO) f V V (H2O) c (O)2 st ] [(OPO) f V V (H2O) s (O)2 ct ] [(OPO) f V V (H2O) t (O)2 ct ] [(OPO) f HV V (OH) c (O)2 st ] [(OPO) f HV V (OH) s (O)2 ct ] [(OPO) f HV V (OH) t (O)2 cs ] (OPO) m V V O s (H2O)2 ta (OPO) m V V O t (H2O)2 sa (OPO) m V V O a (H2O)2 st (OPO) m HV V O s (OH) t (H2O) a geometry unstable N/A 44 6 (OPO) m HV V O s (OH) a (H2O) t geometry unstable N/A 45 6 (OPO) m HV V O t (OH) s (H2O) a geometry unstable N/A 46 6 (OPO) m HV V O t (OH) a (H2O) s (OPO) m HV V O a (OH) s (H2O) t (OPO) m HV V O a (OH) t (H2O) s [(OPO) m V V O s (OH) t (H2O) a ] [(OPO) m V V O s (OH) t (H2O) a ] geometry unstable N/A 51 6 [(OPO) m V V O s (OH) a (H2O) t ] geometry unstable N/A 52 6 [(OPO) m V V O t (OH) s (H2O) a ] [(OPO) m V V O t (OH) a (H2O) s ] geometry unstable N/A 54 6 [(OPO) m V V O a (OH) s (H2O) t ] [(OPO) m HV V O s (OH)2 ta ] [(OPO) m HV V O t (OH)2 sa ] [(OPO) m HV V O a (OH)2 st ] [(OPO) m V V O s (OH)2 ta ] [(OPO) m V V O t (OH)2 sa ] [(OPO) m V V O a (OH)2 st ] [(OPO) m V V (H2O) s (O)2 ta ] 2 geometry unstable N/A 62 6 [(OPO) m V V (H2O) t (O)2 sa ] 2 geometry unstable N/A 63 6 [(OPO) m V V (H2O) a (O)2 st ] 2 geometry unstable N/A 64 6 [(OPO) m HV V (OH) s (O)2 ta ] [(OPO) m HV V (OH) t (O)2 sa ] [(OPO) m HV V (OH) a (O)2 st ]

7 Table S2a. Comprehensive compilation of all the transition states for propane activation by (OPO)V V species, along with their gas-phase energies (Egas) and aqueous free energies (Gaq), both in hartrees; and their aqueous free energies relative to each other (ΔGrel), in kcal/mol. For some entries, geometry optimisation led to the formation of a lower-energy isomer. The energies for these entries are not reported. 4 + iprh 5 (OPO)V V O s (H2O) a + HiPr [(OPO)HiPrVO s (H2O) a ] [(OPO)HiPrVO a (H2O) s ] [(OPO)HiPrVO s (OH) a ] geometry unstable N/A 70 5 [(OPO)HiPrVO a (OH) s ] geometry unstable N/A 71 5 [(OPO)HiPrVO2 sa ] 2 geometry unstable N/A 72 6 [(OPO) f HiPrVO c (H2O)2 st ] [(OPO) f HiPrVO s (H2O)2 ct ] [(OPO) f HiPrVO t (H2O)2 cs ] [(OPO) f HiPrVO c (OH) s (H2O) t ] [(OPO) f HiPrVO c (OH) t (H2O) t ] [(OPO) f HiPrVO s (OH) c (H2O) t ] [(OPO) f HiPrVO s (OH) t (H2O) c ] [(OPO) f HiPrVO t (OH) c (H2O) s ] [(OPO) f HiPrVO t (OH) s (H2O) c ] [(OPO) f HiPrVO c (OH)2 st ] [(OPO) f HiPrVO s (OH)2 ct ] [(OPO) f HiPrVO t (OH)2 cs ] [(OPO) f HiPrV(H2O) c O2 st ] [(OPO) f HiPrV(H2O) s O2 ct ] [(OPO) f HiPrV(H2O) t O2 cs ] [(OPO) m HiPrVO s (H2O)2 ta ] [(OPO) m HiPrVO t (H2O)2 sa ] [(OPO) m HiPrVO a (H2O)2 st ] [(OPO) m HiPrVO s (OH) t (H2O) a ] [(OPO) m HiPrVO s (OH) a (H2O) t ] [(OPO) m HiPrVO t (OH) s (H2O) a ] [(OPO) m HiPrVO t (OH) a (H2O) s ] [(OPO) m HiPrVO a (OH) s (H2O) t ] [(OPO) m HiPrVO a (OH) t (H2O) s ] [(OPO) m HiPrVO s (OH)2 ta ] [(OPO) m HiPrVO t (OH)2 sa ]

8 Table S2b. Continuation from Table S2a [(OPO) m HiPrVO a (OH)2 st ] [(OPO) m HiPrV(H2O) s O2 ta ] [(OPO) m HiPrV(H2O) t O2 sa ] 2 geometry unstable N/A [(OPO) m HiPrV(H2O) a O2 st ] 2 geometry unstable N/A Table S3a. Compilation of all (OPO)V IV species studied, along with their gas-phase energies (Egas) and aqueous free energies (Gaq), both in hartrees; and their aqueous free energies relative to each other (ΔGrel), in kcal/mol (OPO)HV IV O s (H2O) a (OPO)HV IV O a (H2O) s [(OPO)V IV O s (H2O) a ] [(OPO)V IV O a (H2O) s ] (OPO) f V IV (OH) c (H2O)2 st (OPO) f V IV (OH) s (H2O)2 ct (OPO) f V IV (OH) t (H2O)2 cs (OPO) f HV IV (H2O) c (OH)2 st (OPO) f HV IV (H2O) s (OH)2 ct (OPO) f HV IV (H2O) t (OH)2 cs (OPO) f HV IV O c (H2O)2 st (OPO) f HV IV O s (H2O)2 ct (OPO) f HV IV O t (H2O)2 cs [(OPO) f V IV O c (H2O)2 st ] [(OPO) f V IV O s (H2O)2 ct ] [(OPO) f V IV O t (H2O)2 cs ] [(OPO) f HV IV O c (OH) s (H2O) t ] [(OPO) f HV IV O c (OH) t (H2O) s ] [(OPO) f HV IV O s (OH) c (H2O) t ] [(OPO) f HV IV O s (OH) t (H2O) c ] [(OPO) f HV IV O t (OH) c (H2O) s ] [(OPO) f HV IV O t (OH) s (H2O) c ] [(OPO) f V IV O c (OH) s (H2O) t ] [(OPO) f V IV O c (OH) t (H2O) s ] [(OPO) f V IV O s (OH) c (H2O) t ] [(OPO) f V IV O s (OH) t (H2O) c ]

9 Table S3b. Continuation from Table S3a [(OPO) f V IV O t (OH) c (H2O) s ] [(OPO) f V IV O t (OH) s (H2O) c ] [(OPO) f HV IV O c (OH)2 st ] [(OPO) f HV IV O s (OH)2 ct ] [(OPO) f HV IV O t (OH)2 cs ] (OPO) m HV IV O s (H2O)2 ta (OPO) m HV IV O t (H2O)2 sa (OPO) m HV IV O a (H2O)2 st [(OPO) m V IV O s (H2O)2 ta ] [(OPO) m V IV O t (H2O)2 sa ] [(OPO) m V IV O a (H2O)2 st ] Table S4a. Compilation of all (OPO)V III (OiPr) species studied, with only 5- and triplet 6- coordinate fac-(opo) complexes considered. Their gas-phase energies (Egas) and aqueous free energies (Gaq) are both in hartrees, and their aqueous free energies relative to each other (ΔGrel) in kcal/mol. For some entries, geometry optimisation led to the formation of a lower-energy isomer. The energies for these entries are not reported. E. C. Species Egas Gaq ΔGrel [(OPO)V III (HOiPr) s (H2O) a ] geometry unstable N/A [(OPO)V III (HOiPr) s (H2O) a ] [(OPO)V III (HOiPr) a (H2O) s ] geometry unstable N/A [(OPO)V III (HOiPr) a (H2O) s ] geometry unstable N/A [(OPO)HV III (HOiPr) s (OH) a ] [(OPO)HV III (HOiPr) s (OH) a ] [(OPO)HV III (HOiPr) a (OH) s ] geometry unstable N/A [(OPO)HV III (HOiPr) a (OH) s ] geometry unstable N/A [(OPO)HV III (OiPr) s (H2O) a ] geometry unstable N/A [(OPO)HV III (OiPr) s (H2O) a ] [(OPO)HV III (OiPr) a (H2O) s ] [(OPO)HV III (OiPr) a (H2O) s ] [(OPO)HV III (HOiPr) s (H2O) a ] + geometry unstable N/A [(OPO)HV III (HOiPr) s (H2O) a ] + geometry unstable N/A [(OPO)HV III (HOiPr) a (H2O) s ] + geometry unstable N/A [(OPO)HV III (HOiPr) a (H2O) s ] + geometry unstable N/A [(OPO)HV III (OiPr) s (OH) a ]

10 Table S4b. Continuation from Table S4a. E. C. Species Egas Gaq ΔGrel [(OPO)HV III (OiPr) s (OH) a ] [(OPO)HV III (OiPr) a (OH) s ] geometry unstable N/A [(OPO)HV III (OiPr) a (OH) s ] [(OPO)V III (HOiPr) s (OH) a ] [(OPO)V III (HOiPr) s (OH) a ] geometry unstable N/A [(OPO)V III (HOiPr) a (OH) s ] geometry unstable N/A [(OPO)V III (HOiPr) a (OH) s ] geometry unstable N/A [(OPO)V III (OiPr) s (H2O) a ] [(OPO)V III (OiPr) s (H2O) a ] geometry unstable N/A [(OPO)V III (OiPr) a (H2O) s ] [(OPO)V III (OiPr) a (H2O) s ] geometry unstable N/A [(OPO) f V III (HOiPr) c (H2O)2 st ] [(OPO) f V III (HOiPr) s (H2O)2 ct ] [(OPO) f V III (HOiPr) t (H2O)2 cs ] [(OPO) f HV III (HOiPr) c (OH) s (H2O) t ] [(OPO) f HV III (HOiPr) c (OH) t (H2O) s ] [(OPO) f HV III (HOiPr) s (OH) c (H2O) t ] [(OPO) f HV III (HOiPr) s (OH) t (H2O) c ] [(OPO) f HV III (HOiPr) t (OH) c (H2O) s ] [(OPO) f HV III (HOiPr) t (OH) s (H2O) c ] [(OPO) f HV III (OiPr) c (H2O)2 st ] [(OPO) f HV III (OiPr) s (H2O)2 ct ] [(OPO) f HV III (OiPr) t (H2O)2 cs ] [(OPO) f V III (HOiPr) c (OH) s (H2O) t ] [(OPO) f V III (HOiPr) c (OH) t (H2O) s ] [(OPO) f V III (HOiPr) s (OH) c (H2O) t ] [(OPO) f V III (HOiPr) s (OH) t (H2O) c ] [(OPO) f V III (HOiPr) t (OH) c (H2O) s ] [(OPO) f V III (HOiPr) t (OH) s (H2O) c ] [(OPO) f V III (OiPr) c (H2O)2 st ] [(OPO) f V III (OiPr) s (H2O)2 ct ] [(OPO) f V III (OiPr) t (H2O)2 cs ] [(OPO) f HV III (HOiPr) c (OH)2 st ] geometry unstable N/A [(OPO) f HV III (HOiPr) s (OH)2 ct ] [(OPO) f HV III (HOiPr) t (OH)2 cs ] [(OPO) f HV III (OiPr) c (OH) s (H2O) t ] [(OPO) f HV III (OiPr) c (OH) t (H2O) s ]

11 Table S4c. Continuation from Table S4b. E. C. Species Egas Gaq ΔGrel [(OPO) f HV III (OiPr) s (OH) c (H2O) t ] [(OPO) f HV III (OiPr) s (OH) t (H2O) c ] [(OPO) f HV III (OiPr) t (OH) c (H2O) s ] geometry unstable N/A [(OPO) f HV III (OiPr) t (OH) s (H2O) c ] Table S5a. Comprehensive compilation of all (OPO)V III species containing only hydroxo/aqua ligands studied, along with their gas-phase energies (Egas) and aqueous free energies (Gaq), both in hartrees, and their aqueous free energies relative to each other (ΔGrel) in kcal/mol. For some entries, geometry optimisation led to the formation of a lower-energy isomer. The energies for these entries are not reported. Entry Coord. Species Egas Gaq ΔGrel [(OPO)V III (H2O)2 sa ] [(OPO)V III (H2O)2 sa ] [(OPO)HV III (OH) s (H2O) a ] geometry unstable N/A [(OPO)HV III (OH) s (H2O) a ] [(OPO)HV III (OH) a (H2O) s ] [(OPO)HV III (OH) a (H2O) s ] [(OPO)V III (OH) s (H2O) a ] geometry unstable N/A [(OPO)V III (OH) s (H2O) a ] [(OPO)V III (OH) a (H2O) s ] geometry unstable N/A [(OPO)V III (OH) a (H2O) s ] [(OPO)HV III (OH)2 sa ] geometry unstable N/A [(OPO)HV III (OH)2 sa ] geometry unstable N/A [(OPO) f V III (H2O)3 cst ] [(OPO) f V III (H2O)3 cst ] [(OPO) f HV III (OH) c (H2O)2 st ] [(OPO) f HV III (OH) c (H2O)2 st ] [(OPO) f HV III (OH) s (H2O)2 ct ] [(OPO) f HV III (OH) s (H2O)2 ct ] [(OPO) f HV III (OH) t (H2O)2 cs ] [(OPO) f HV III (OH) t (H2O)2 cs ] [(OPO) f V III (OH) c (H2O)2 st ] [(OPO) f V III (OH) c (H2O)2 st ] [(OPO) f V III (OH) s (H2O)2 ct ] [(OPO) f V III (OH) s (H2O)2 ct ]

12 Table S5b. Continuation from Table S5a. Entry Coord. Species Egas Gaq ΔGrel [(OPO) f V III (OH) t (H2O)2 cs ] [(OPO) f V III (OH) t (H2O)2 cs ] [(OPO) f HV III (H2O) c (OH)2 st ] [(OPO) f HV III (H2O) c (OH)2 st ] [(OPO) f HV III (H2O) s (OH)2 ct ] [(OPO) f HV III (H2O) s (OH)2 ct ] [(OPO) f HV III (H2O) t (OH)2 cs ] [(OPO) f HV III (H2O) t (OH)2 cs ] [(OPO) m V III (H2O)3 sta ] [(OPO) m V III (H2O)3 sta ] [(OPO) m HV III (OH) s (H2O)2 ta ] [(OPO) m HV III (OH) s (H2O)2 ta ] [(OPO) m HV III (OH) t (H2O)2 sa ] [(OPO) m HV III (OH) t (H2O)2 sa ] [(OPO) m HV III (OH) a (H2O)2 st ] [(OPO) m HV III (OH) a (H2O)2 st ] [(OPO) m V III (OH) s (H2O)2 ta ] [(OPO) m V III (OH) s (H2O)2 ta ] [(OPO) m V III (OH) t (H2O)2 sa ] [(OPO) m V III (OH) t (H2O)2 sa ] [(OPO) m V III (OH) a (H2O)2 st ] [(OPO) m V III (OH) a (H2O)2 st ] [(OPO) m V III (H2O) s (OH)2 ta ] [(OPO) m HV III (H2O) s (OH)2 ta ] [(OPO) m HV III (H2O) t (OH)2 sa ] [(OPO) m HV III (H2O) t (OH)2 sa ] [(OPO) m HV III (H2O) a (OH)2 st ] [(OPO) m HV III (H2O) a (OH)2 st ] Table S6a. Comprehensive compilation of all (OPO)V V (OiPr)(O2) peroxide species studied, along with their gas-phase energies (Egas) and aqueous free energies (Gaq), both in hartrees, and their aqueous free energies relative to each other (ΔGrel) in kcal/mol. Note that a and b labels on O2 represent whether the O2 ligand is parallel or perpendicular to the PO moiety. For some entries, geometry optimisation led to the formation of a lower-energy isomer. The energies for these entries are not reported.

13 249 5 (OPO)V V (HOiPr) s (O2-a) a geometry unstable N/A (OPO)V V (HOiPr) s (O2-b) a geometry unstable N/A (OPO)V V (HOiPr) a (O2-a) s geometry unstable N/A (OPO)V V (HOiPr) a (O2-b) s geometry unstable N/A (OPO)HV V (OiPr) s (O2-a) a (OPO)HV V (OiPr) s (O2-b) a (OPO)HV V (OiPr) a (O2-a) s geometry unstable N/A (OPO)HV V (OiPr) a (O2-b) s geometry unstable N/A (OPO)V V (OiPr) s (OOH) a (OPO)V V (OiPr) a (OOH) s geometry unstable N/A [(OPO)HV V (HOiPr) s (O2-a) a ] + geometry unstable N/A [(OPO)HV V (HOiPr) s (O2-b) a ] + geometry unstable N/A [(OPO)HV V (HOiPr) a (O2-a) s ] + geometry unstable N/A [(OPO)HV V (HOiPr) a (O2-b) s ] + geometry unstable N/A [(OPO)V V (OiPr) s (O2-a) a ] [(OPO)V V (OiPr) s (O2-b) a ] [(OPO)V V (OiPr) a (O2-a) s ] [(OPO)V V (OiPr) a (O2-b) s ] (OPO) f V V (HOiPr) c (O2-a) s (H2O) t (OPO) f V V (HOiPr) c (O2-b) s (H2O) t (OPO) f V V (HOiPr) c (O2-a) t (H2O) s (OPO) f V V (HOiPr) c (O2-b) t (H2O) s (OPO) f V V (HOiPr) s (O2-a) c (H2O) t (OPO) f V V (HOiPr) s (O2-b) c (H2O) t (OPO) f V V (HOiPr) s (O2-a) t (H2O) c (OPO) f V V (HOiPr) s (O2-b) t (H2O) c (OPO) f V V (HOiPr) t (O2-a) c (H2O) s (OPO) f V V (HOiPr) t (O2-b) c (H2O) s (OPO) f V V (HOiPr) t (O2-a) s (H2O) c (OPO) f V V (HOiPr) t (O2-b) s (H2O) c (OPO) f HV V (HOiPr) c (O2-a) s (OH) t (OPO) f HV V (HOiPr) c (O2-b) s (OH) t (OPO) f HV V (HOiPr) c (O2-a) t (OH) s (OPO) f HV V (HOiPr) c (O2-b) t (OH) s (OPO) f HV V (HOiPr) s (O2-a) c (OH) t (OPO) f HV V (HOiPr) s (O2-b) c (OH) t (OPO) f HV V (HOiPr) s (O2-a) t (OH) c (OPO) f HV V (HOiPr) s (O2-b) t (OH) c

14 Table S6b. Continuation from Table S6a (OPO) f HV V (HOiPr) t (O2-a) c (OH) s (OPO) f HV V (HOiPr) t (O2-b) c (OH) s (OPO) f HV V (HOiPr) t (O2-a) s (OH) c (OPO) f HV V (HOiPr) t (O2-b) s (OH) c (OPO) f HV V (OiPr) c (O2-a) s (H2O) t (OPO) f HV V (OiPr) c (O2-b) s (H2O) t (OPO) f HV V (OiPr) c (O2-a) t (H2O) s (OPO) f HV V (OiPr) c (O2-b) t (H2O) s (OPO) f HV V (OiPr) s (O2-a) c (H2O) t (OPO) f HV V (OiPr) s (O2-b) c (H2O) t (OPO) f HV V (OiPr) s (O2-a) t (H2O) c (OPO) f HV V (OiPr) s (O2-b) t (H2O) c (OPO) f HV V (OiPr) t (O2-a) c (H2O) s (OPO) f HV V (OiPr) t (O2-b) c (H2O) s (OPO) f HV V (OiPr) t (O2-a) s (H2O) c (OPO) f HV V (OiPr) t (O2-b) s (H2O) c (OPO) m HV V (OiPr) s (O2-a) t (H2O) a (OPO) m HV V (OiPr) s (O2-b) t (H2O) a (OPO) m HV V (OiPr) s (O2-a) a (H2O) t (OPO) m HV V (OiPr) s (O2-b) a (H2O) t (OPO) m HV V (OiPr) t (O2-a) s (H2O) a (OPO) m HV V (OiPr) t (O2-b) s (H2O) a (OPO) m HV V (OiPr) t (O2-a) a (H2O) s (OPO) m HV V (OiPr) t (O2-b) a (H2O) s (OPO) m HV V (OiPr) a (O2-a) s (H2O) t (OPO) m HV V (OiPr) a (O2-b) s (H2O) t (OPO) m HV V (OiPr) a (O2-a) t (H2O) s (OPO) m HV V (OiPr) a (O2-b) t (H2O) s (OPO) m V V (HOiPr) s (O2-a) t (H2O) a (OPO) m V V (HOiPr) s (O2-b) t (H2O) a (OPO) m V V (HOiPr) s (O2-a) a (H2O) t (OPO) m V V (HOiPr) s (O2-b) a (H2O) t (OPO) m V V (HOiPr) t (O2-a) s (H2O) a (OPO) m V V (HOiPr) t (O2-b) s (H2O) a geometry unstable N/A (OPO) m V V (HOiPr) t (O2-a) a (H2O) s (OPO) m V V (HOiPr) t (O2-b) a (H2O) s (OPO) m V V (HOiPr) a (O2-a) s (H2O) t

15 Table S6c. Continuation from Table S6b (OPO) m V V (HOiPr) a (O2-b) s (H2O) t (OPO) m V V (HOiPr) a (O2-a) t (H2O) s (OPO) m V V (HOiPr) a (O2-b) t (H2O) s [(OPO) m V V (OiPr) s (O2-a) t (H2O) a ] [(OPO) m V V (OiPr) s (O2-b) t (H2O) a ] [(OPO) m V V (OiPr) s (O2-a) a (H2O) t ] [(OPO) m V V (OiPr) s (O2-b) a (H2O) t ] [(OPO) m V V (OiPr) t (O2-a) s (H2O) a ] [(OPO) m V V (OiPr) t (O2-b) s (H2O) a ] [(OPO) m V V (OiPr) t (O2-a) a (H2O) s ] [(OPO) m V V (OiPr) t (O2-b) a (H2O) s ] [(OPO) m V V (OiPr) a (O2-a) s (H2O) t ] [(OPO) m V V (OiPr) a (O2-b) s (H2O) t ] [(OPO) m V V (OiPr) a (O2-a) t (H2O) s ] [(OPO) m V V (OiPr) a (O2-b) t (H2O) s ] (OPO) f V V (HOiPr) c (HOOH) s O t (OPO) f V V (HOiPr) c (HOOH) t O s geometry unstable N/A (OPO) f V V (HOiPr) s (HOOH) c O t geometry unstable N/A (OPO) f V V (HOiPr) s (HOOH) t O c geometry unstable N/A (OPO) f V V (HOiPr) t (HOOH) c O s geometry unstable N/A (OPO) f V V (HOiPr) t (HOOH) s O c geometry unstable N/A (OPO) f V V (HOiPr) c (OOH) s (OH) t (OPO) f V V (HOiPr) c (OOH) t (OH) s (OPO) f V V (HOiPr) s (OOH) c (OH) t geometry unstable N/A (OPO) f V V (HOiPr) s (OOH) t (OH) c (OPO) f V V (HOiPr) t (OOH) c (OH) s (OPO) f V V (HOiPr) t (OOH) s (OH) c (OPO) f V V (OiPr) c (HOOH) s (OH) t (OPO) f V V (OiPr) c (HOOH) t (OH) s (OPO) f V V (OiPr) s (HOOH) c (OH) t geometry unstable N/A (OPO) f V V (OiPr) s (HOOH) t (OH) c (OPO) f V V (OiPr) t (HOOH) c (OH) s geometry unstable N/A (OPO) f V V (OiPr) t (HOOH) s (OH) c (OPO) f V V (OiPr) c (OOH) s (H2O) t (OPO) f V V (OiPr) c (OOH) t (H2O) s (OPO) f V V (OiPr) s (OOH) c (H2O) t (OPO) f V V (OiPr) s (OOH) t (H2O) c

16 Table S6d. Continuation from Table S6c (OPO) f V V (OiPr) t (OOH) c (H2O) s (OPO) f V V (OiPr) t (OOH) s (H2O) c (OPO) f HV V (HOiPr) c (OOH) s O t (OPO) f HV V (HOiPr) c (OOH) t O s (OPO) f HV V (HOiPr) s (OOH) c O t (OPO) f HV V (HOiPr) s (OOH) t O c (OPO) f HV V (HOiPr) t (OOH) c O s (OPO) f HV V (HOiPr) t (OOH) s O c (OPO) f HV V (OiPr) c (HOOH) s O t (OPO) f HV V (OiPr) c (HOOH) t O s (OPO) f HV V (OiPr) s (HOOH) c O t (OPO) f HV V (OiPr) s (HOOH) t O c (OPO) f HV V (OiPr) t (HOOH) c O s (OPO) f HV V (OiPr) t (HOOH) s O c (OPO) f HV V (OiPr) c (OOH) s (OH) t geometry unstable N/A (OPO) f HV V (OiPr) c (OOH) t (OH) s (OPO) f HV V (OiPr) s (OOH) c (OH) t (OPO) f HV V (OiPr) s (OOH) t (OH) c (OPO) f HV V (OiPr) t (OOH) c (OH) s (OPO) f HV V (OiPr) t (OOH) s (OH) c Table S7a. Compilation of all (OPO)V V (O2) peroxide species containing only oxo/hydroxo/aqua ligands studied, along with their gas-phase energies (Egas) and aqueous free energies (Gaq), both in hartrees, and their aqueous free energies relative to each other (ΔGrel) in kcal/mol. Note that a and b labels on O2 represent whether the O2 ligand is parallel or perpendicular to the PO moiety. For some entries, geometry optimisation led to the formation of a lower-energy isomer. The energies for these entries are not reported (OPO)V V (O2-a) s (H2O) a (OPO)V V (O2-b) s (H2O) a (OPO)V V (O2-a) a (H2O) s geometry unstable N/A (OPO)V V (O2-b) a (H2O) s geometry unstable N/A (OPO)HV V (O2-a) s (OH) a (OPO)HV V (O2-b) s (OH) a geometry unstable N/A (OPO)HV V (O2-a) a (OH) s geometry unstable N/A

17 Table S7b. Continuation from Table S7a. Entry C. Species Egas Gaq (OPO)HV V (O2-b) a (OH) s geometry unstable N/A (OPO)V V O s (η 1 -HOOH) a (OPO)V V O s (η 2 -HOOH) a (OPO)V V O a (η 1 -HOOH) s geometry unstable N/A (OPO)V V O a (η 2 -HOOH) s (OPO)V V (OH) s (η 1 -OOH) a geometry unstable N/A (OPO)V V (OH) s (η 2 -OOH) a geometry unstable N/A (OPO)V V (OH) a (η 1 -OOH) s (OPO)V V (OH) a (η 2 -OOH) s (OPO)HV V O s (η 1 -OOH) a geometry unstable N/A (OPO)HV V O s (η 2 -OOH) a (OPO)HV V O a (η 1 -OOH) s (OPO)HV V O a (η 2 -OOH) s [(OPO)HV V (O2-a) s (H2O) a ] N/A [(OPO)HV V (O2-b) s (H2O) a ] + geometry unstable N/A [(OPO)HV V (O2-a) a (H2O) s ] + geometry unstable N/A [(OPO)HV V (O2-b) a (H2O) s ] + geometry unstable N/A [(OPO)V V (O2-a) s (OH) a ] [(OPO)V V (O2-b) s (OH) a ] N/A [(OPO)V V (O2-a) a (OH) s ] [(OPO)V V (O2-b) a (OH) s ] geometry unstable N/A (OPO) f V V (O2-a) c (H2O)2 st (OPO) f V V (O2-b) c (H2O)2 st (OPO) f V V (O2-a) s (H2O)2 ct (OPO) f V V (O2-b) s (H2O)2 ct (OPO) f V V (O2-a) t (H2O)2 cs (OPO) f V V (O2-b) t (H2O)2 cs (OPO) f HV V (O2-a) c (OH) s (H2O) t (OPO) f HV V (O2-b) c (OH) s (H2O) t (OPO) f HV V (O2-a) c (OH) t (H2O) s (OPO) f HV V (O2-b) c (OH) t (H2O) s (OPO) f HV V (O2-a) s (OH) c (H2O) t (OPO) f HV V (O2-b) s (OH) c (H2O) t (OPO) f HV V (O2-a) s (OH) t (H2O) c (OPO) f HV V (O2-b) s (OH) t (H2O) c (OPO) f HV V (O2-a) t (OH) c (H2O) s (OPO) f HV V (O2-b) t (OH) c (H2O) s

18 Table S7c. Continuation from Table S7b (OPO) f HV V (O2-a) t (OH) s (H2O) c (OPO) f HV V (O2-b) t (OH) s (H2O) c (OPO) f V V O c (HOOH) s (H2O) t (OPO) f V V O c (HOOH) t (H2O) s (OPO) f V V O s (HOOH) c (H2O) t (OPO) f V V O s (HOOH) t (H2O) c (OPO) f V V O t (HOOH) c (H2O) s (OPO) f V V O t (HOOH) s (H2O) c (OPO) f HV V O c (OOH) s (H2O) t (OPO) f HV V O c (OOH) t (H2O) s (OPO) f HV V O s (OOH) c (H2O) t (OPO) f HV V O s (OOH) t (H2O) c (OPO) f HV V O t (OOH) c (H2O) s (OPO) f HV V O t (OOH) s (H2O) c (OPO) f HV V O c (HOOH) s (OH) t (OPO) f HV V O c (HOOH) t (OH) s (OPO) f HV V O s (HOOH) c (OH) t (OPO) f HV V O s (HOOH) t (OH) c (OPO) f HV V O t (HOOH) c (OH) s (OPO) f HV V O t (HOOH) s (OH) c (OPO) f V V (HOOH) c (OH)2 st geometry unstable N/A (OPO) f V V (HOOH) s (OH)2 ct geometry unstable N/A (OPO) f V V (HOOH) t (OH)2 cs (OPO) f V V (OOH) c (OH) s (H2O) t geometry unstable N/A (OPO) f V V (OOH) c (OH) t (H2O) c (OPO) f V V (OOH) s (OH) c (H2O) t geometry unstable N/A (OPO) f V V (OOH) s (OH) t (H2O) c (OPO) f V V (OOH) t (OH) s (H2O) c (OPO) f V V (OOH) t (OH) c (H2O) s (OPO) f HV V (OOH) c (OH)2 st (OPO) f HV V (OOH) s (OH)2 ct (OPO) f HV V (OOH) t (OH)2 cs

19 Table S8. Data for the two dimeric species studied, consisting of their gas-phase energies (Egas) and aqueous free energies (Gaq), both in hartrees, and their aqueous free energies relative to each other (ΔGrel) in kcal/mol , 6 1 {[(OPO) f V(H2O)2 st O c ] [O s (H2O)2 ct V(OPO) f ]} , 6 3 {[(OPO) f V IV (H2O)2 st O c ] [O s (H2O)2 ct V IV (OPO) f ]} Table S9. Compilation of all (OPO)V V (OiPr) species studied, along with their gas-phase energies (Egas) and aqueous free energies (Gaq), both in hartrees, and their aqueous free energies relative to each other (ΔGrel) in kcal/mol. Only species containing a V=O moiety were considered. For some entries, geometry optimisation led to the formation of a lower-energy isomer. The energies for these entries are not reported. Entry Coord. Species Egas Gaq ΔGrel (OPO)V V O s (HOiPr) a (OPO)V V O a (HOiPr) s geometry unstable N/A (OPO)HV V O s (OiPr) a geometry unstable N/A (OPO)HV V O a (OiPr) s (OPO) f V V O c (HOiPr) s (H2O) t (OPO) f V V O c (HOiPr) t (H2O) s (OPO) f V V O s (HOiPr) c (H2O) t (OPO) f V V O s (HOiPr) t (H2O) c (OPO) f V V O t (HOiPr) c (H2O) s (OPO) f V V O t (HOiPr) s (H2O) c (OPO) f HV V O c (HOiPr) s (OH) t (OPO) f HV V O c (HOiPr) t (OH) s (OPO) f HV V O s (HOiPr) c (OH) t geometry unstable N/A (OPO) f HV V O s (HOiPr) t (OH) c (OPO) f HV V O t (HOiPr) c (OH) s (OPO) f HV V O t (HOiPr) s (OH) c (OPO) f HV V O c (OiPr) s (H2O) t (OPO) f HV V O c (OiPr) t (H2O) s (OPO) f HV V O s (OiPr) c (H2O) t (OPO) f HV V O s (OiPr) t (H2O) c (OPO) f HV V O t (OiPr) c (H2O) s (OPO) f HV V O t (OiPr) s (H2O) c

20 Table S10. Compilation of all (OPO)V III (O2)(OiPr) peroxide species containing isopropoxy ligands studied, along with their gas-phase energies (Egas) and aqueous free energies (Gaq), both in hartrees, and their aqueous free energies relative to each other (ΔGrel) in kcal/mol. Note that only neutral triplet 5-coordinate and 6-coordinate fac-(opo) complexes were studied. For some entries, geometry optimisation led to the formation of a lower-energy isomer. The energies for these entries are not reported [(OPO)V III (HOiPr) s (H2O2) a ] geometry unstable N/A [(OPO)V III (HOiPr) a (H2O2) s ] [(OPO)HV III (OiPr) s (H2O2) a ] [(OPO)HV III (OiPr) a (H2O2) s ] [(OPO)HV III (HOiPr) s (η 1 -OOH) a ] geometry unstable N/A [(OPO)HV III (HOiPr) a (η 1 -OOH) s ] [(OPO)HV III (HOiPr) s (η 2 -OOH) a ] [(OPO)HV III (HOiPr) a (η 2 -OOH) s ] [(OPO) f V III (HOiPr) c (HOOH) s (H2O) t ] [(OPO) f V III (HOiPr) c (HOOH) t (H2O) s ] [(OPO) f V III (HOiPr) s (HOOH) c (H2O) t ] [(OPO) f V III (HOiPr) s (HOOH) t (H2O) c ] [(OPO) f V III (HOiPr) t (HOOH) c (H2O) s ] [(OPO) f V III (HOiPr) t (HOOH) s (H2O) c ] [(OPO) f HV III (HOiPr) c (HOOH) s (OH) t ] geometry unstable N/A [(OPO) f HV III (HOiPr) c (HOOH) t (OH) s ] [(OPO) f HV III (HOiPr) s (HOOH) c (OH) t ] [(OPO) f HV III (HOiPr) s (HOOH) t (OH) c ] [(OPO) f HV III (HOiPr) t (HOOH) c (OH) s ] [(OPO) f HV III (HOiPr) t (HOOH) s (OH) c ] [(OPO) f HV III (HOiPr) c (OOH) s (H2O) t ] [(OPO) f HV III (HOiPr) c (OOH) t (H2O) s ] [(OPO) f HV III (HOiPr) s (OOH) c (H2O) t ] [(OPO) f HV III (HOiPr) s (OOH) t (H2O) c ] [(OPO) f HV III (HOiPr) t (OOH) c (H2O) s ] [(OPO) f HV III (HOiPr) t (OOH) s (H2O) c ] [(OPO) f HV III (OiPr) c (HOOH) s (H2O) t ] [(OPO) f HV III (OiPr) c (HOOH) t (H2O) s ] [(OPO) f HV III (OiPr) s (HOOH) c (H2O) t ] [(OPO) f HV III (OiPr) s (HOOH) t (H2O) c ] [(OPO) f HV III (OiPr) t (HOOH) c (H2O) s ] [(OPO) f HV III (OiPr) t (HOOH) s (H2O) c ]

21 Table S11. Compilation of [(OPO)HV(HOiPr)(O OH)] transition state species, which represent the transition from (OPO)HV III (HOiPr)(OOH) ( ) to (OPO) f HV V O(OH)(HOiPr) ( ). Given are their gas-phase energies (Egas) and aqueous free energies (Gaq), both in hartrees, and their aqueous free energies relative to 3 [(OPO) f HV III (HOiPr) s (OOH) c (H2O) t ] (503) (ΔGrel) in kcal/mol. Note that only neutral transition states between 5-coordinate and 6- coordinate fac-(opo) complexes were studied. Also note that all transition states found involve OOH bound in an η 2 -fashion splitting into oxo and hydroxo ligands. For some entries, the transition state was not found, and energies for those entries are not reported. E. Coord. Species Egas Gaq ΔGrel [(OPO)HV(HOiPr) s (O OH) a ] not found N/A [(OPO)HV(HOiPr) s (O OH) a ] [(OPO)HV(HOiPr) a (O OH) s ] [(OPO)HV(HOiPr) a (O OH) s ] Table S12a. Compilation of all (OPO)V III (O2) peroxide species containing only oxo/hydroxo/aqua ligands studied, along with their gas-phase energies (Egas) and aqueous free energies (Gaq), both in hartrees, and their aqueous free energies relative to each other (ΔGrel) in kcal/mol. Note that only neutral triplet 5-coordinate and 6-coordinate fac-(opo) complexes were studied. Also note that HOOH/OOH binds exclusively in an η 1 -fashion in the fac-(opo) complexes. For some entries, geometry optimisation led to the formation of a lower-energy isomer. The energies for these entries are not reported [(OPO)V III (η 1 -HOOH) s (H2O) a ] [(OPO)V III (η 1 -HOOH) a (H2O) s ] [(OPO)V III (η 2 -HOOH) s (H2O) a ] [(OPO)V III (η 2 -HOOH) a (H2O) s ] geometry unstable N/A [(OPO)HV III (η 1 -HOOH) s (OH) a ] [(OPO)HV III (η 1 -HOOH) a (OH) s ] [(OPO)HV III (η 2 -HOOH) s (OH) a ] geometry unstable N/A [(OPO)HV III (η 2 -HOOH) a (OH) s ] geometry unstable N/A [(OPO)HV III (η 1 -OOH) s (H2O) a ] [(OPO)HV III (η 1 -OOH) a (H2O) s ] [(OPO)HV III (η 2 -OOH) s (H2O) a ] [(OPO)HV III (η 2 -OOH) a (H2O) s ] [(OPO) f V III (HOOH) c (H2O)2 st ] [(OPO) f V III (HOOH) s (H2O)2 ct ] [(OPO) f V III (HOOH) t (H2O)2 cs ]

22 Table S12b. Continuation from Table S12a [(OPO) f HV III (HOOH) c (OH) s (H2O) t ] [(OPO) f HV III (HOOH) c (OH) t (H2O) s ] [(OPO) f HV III (HOOH) s (OH) c (H2O) t ] [(OPO) f HV III (HOOH) s (OH) t (H2O) c ] [(OPO) f HV III (HOOH) t (OH) c (H2O) s ] [(OPO) f HV III (HOOH) t (OH) s (H2O) c ] [(OPO) f HV III (OOH) c (H2O)2 st ] [(OPO) f HV III (OOH) s (H2O)2 ct ] [(OPO) f HV III (OOH) t (H2O)2 cs ] Table S13. Compilation of [(OPO)HV(O OH)(H2O)] transition state species, which represent the transition from (OPO)HV III (OOH)(H2O) ( ) to (OPO) f HV V O(OH)(H2O) (16-21). Given are their gas-phase energies (Egas) and aqueous free energies (Gaq), both in hartrees, and their aqueous free energies relative to 3 [(OPO) f HV III (OOH) c (H2O)2 st ] (538) (ΔGrel) in kcal/mol. Note that only neutral transition states between 5-coordinate and 6-coordinate fac-(opo) complexes were studied. Also note that all transition states found involve OOH bound in an η 2 -fashion splitting into oxo and hydroxo ligands. For some entries, the transition state was not found, and energies for those entries are not reported. Entry Coord. Species Egas Gaq ΔGrel [(OPO)HV(O OH) s (H2O) a ] [(OPO)HV(O OH) s (H2O) a ] [(OPO)HV(O OH) a (H2O) s ] not found N/A [(OPO)HV(O OH) a (H2O) s ]