Article pubs.acs.org/IC
Quantum Chemical Investigation of the Transition States and Intermediates for the Reaction of the Nitrosonium Ion with the Pentaammineazidocobalt(III) Ion François P. Rotzinger* Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 6, CH-1015 Lausanne, Switzerland S Supporting Information *
ABSTRACT: The water exchange reaction on Co(NH3)5OH23+ was investigated with various density functionals and basis sets. A Gibbs activation energy (ΔG⧧) agreeing with experiment was obtained with the long-range-corrected functionals ωB97X-D3 and LC-BOP-LRD, SMD hydration, and modified Karlsruhe def2-TZVP basis sets. This computational technique was then applied to the reaction of NO+ with Co(NH3)5N32+. All of the possible pathways were investigated, NO+ attack at the terminal N of Co(NH3)5N32+ via the E and the Z isomers of the transition states, and NO+ attack at the bound N of azide, also via both isomers. The most favorable pathway proceeds via the attack at the bound N via the Z isomer. This leads to the intermediate with an oxatetrazole ligand bound to Co(III) at the N in the 3-position, Co(NH3)5(cycl-N4O)3+, which undergoes N2 elimination to yield the Co(NH3)5N2O3+ intermediate. The subsequent substitution of N2O by water follows the Id mechanism with retention of the configuration. No evidence for the existence of the square-pyramidal pentacoordinated intermediate Co(NH3)53+ was found. All of the investigated intermediates, Co(NH3)5N23+, Co(NH3)5[E-N(N2)(NO)]3+, Co(NH3)5(E-ON4)3+, Co(NH3)5ON23+, Co(NH3)5(cycl-N4O)3+, and Co(NH3)5N2O3+, exhibit short lifetimes of less than ∼60 μs and react via the Id mechanism.
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INTRODUCTION The title reaction 1, 2 HONO + H+ ⇄ H 2O + NO+
Other leaving groups were assumed to be much less reactive than N2 and N2O, and less prone to form the putative pentacoordinated intermediate. All of these studies1−6 did not allow answering the question on the existence of the pentacoordinated intermediate Co(NH3)53+. About 10 years later, quantum chemical computations on substitution reactions of pentaammine complexes of cobalt(III), Co(NH3)5Xn+ (X = OH2, Cl−, NCS−, SCN−), suggested9−11 the Id mechanism.12−14 It should be noted, however, that basecatalyzed substitution reactions may proceed via penta- or hexacoordinated intermediates.15−18 In the present study, quantum chemical computations were performed on reaction 2. The detailed reaction mechanism was elucidated via the calculation of all the transition states and intermediates to answer the question of the existence and lifetime of the Co(NH3)5N4O3+, Co(NH3)5N2O3+, Co(NH3)5N23+, and other intermediates, and to determine their substitution mechanism.
(1)
Co(NH3)5 N32 + + NO+ + H 2O/Y m − → Co(NH3)5 OH 2 3 +/Co(NH3)5 Y (3 − m) + + N2 + N2O (2)
was studied1−6 from the early 1960s until the end of the 1980s to prove the existence or the nonexistence of the pentacoordinated intermediate Co(NH3)53+. Since the equilibrium of (1) lies on the left, the concentration of NO+ is low. The rate of the reaction is first-order in each, [H+], [HONO], and [Co(NH3)5N32+] under the experimental conditions. In the presence of nucleophiles, Ym−, there are additional terms in [Y m− ], and pentaammine complexes with coordinated nucleophiles, Co(NH3)5Y(3−m)+, are formed. The NO+ ion is a strong oxidant,7,8 reacting with HONO, yielding NO, NO2, and H+. This side reaction did not perturb the kinetic measurements and the product analysis. Reaction 2 was suggested1−6 to proceed according to Scheme 1. The Co(NH3)5N23+ and Co(NH3)5N2O3+ intermediates, formed after the attack of NO+ at Co(NH3)5N32+, were believed to exhibit highly reactive leaving groups that might form eventually the Co(NH3)53+ intermediate, which itself would scavenge very rapidly water or nucleophiles. © XXXX American Chemical Society
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COMPUTATIONAL DETAILS
The calculations were performed with the GAMESS programs.19,20 Karlsruhe def2-SV(P), def2-SVP, and def2-TZVP basis sets,21−23 Received: August 8, 2016
A
DOI: 10.1021/acs.inorgchem.6b01915 Inorg. Chem. XXXX, XXX, XXX−XXX
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Inorganic Chemistry Scheme 1a
a
H atoms of NH3 are omitted.
modified as described previously24 and denoted as sv(p), svp, and tzvp, were used. The figures were generated with MacMolPlt.25 The geometries and vibrational frequencies were computed with density functional theory (DFT) and SMD26 hydration (with a finer tessalation than the default, ntsall = 960 instead of 60). The longrange-corrected functionals LC-BOP-LRD27,28 and ωB97X-D329 were used, whereby the latter was added to GAMESS (5 Dec 2014 R1). A grid finer than the default was used (nrad = 120, nleb = 770 for LC-BOP-LRD, and nrad = 160, nleb = 770 for ωB97X-D3; the respective defaults are 96 and 302). The Hessians were calculated numerically (based on analytical gradients) using the double-difference method and projected to eliminate rotational and translational contaminants.30 The Gibbs reaction (ΔG) and activation (ΔG⧧) energies were calculated for 25 °C as described previously.31,32 The transition states (TS) were located by maximizing the energy along the reaction coordinate (the imaginary mode) via eigenmode following. They exhibited a single imaginary frequency. Reactants, products, and intermediates were obtained via computation of the intrinsic reaction coordinate. All of their computed vibrational frequencies were real. The atomic coordinates of all of the investigated cobalt(III) complexes (ωB97X-D3-SMD/tzvp level) are given in the Supporting Information.
Figure 1. Structure and imaginary mode (91i cm−1) of the transition state Co(NH3)5···(OH2)23+ ⧧ (ωB97X-D3-SMD/tzvp).
Table 1. Electronic (ΔE⧧) and Gibbs (ΔG⧧) Activation Energya for the Water Exchange Reaction 3 of Co(NH3)5OH23+
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RESULTS AND DISCUSSION Validation of the Computational Method. The performance of various functionals and basis sets was assessed by the computation of the Gibbs activation energy (ΔG⧧) for the water exchange reaction 3 of Co(NH3)5OH23+. Co(NH3)5 OH 2 3 + + H 2O a
→ Co(NH3)5 ···(OH 2)(OH 2)3 + ⧧ → Co(NH3)5 OH 2 3 + + H 2O
(3)
method
ΔE⧧
ΔG⧧
ωB97X-D3-SMD/tzvp ωB97X-D3-SMD/svp ωB97X-D3-SMD/sv(p) LC-BOP-LRD-SMD/tzvp BPBE-D3-SMD/tzvp PBE0-D3-SMD/tzvp PBE-D3-SMD/tzvp CAM-B3LYP-D3-SMD/tzvp
63.3 41.9 44.7 69.5 59.7 60.0 48.2 61.9
94.2 67.8 61.1 89.3 69.8 80.6 63.2 82.9
Units: kJ mol−1.
basis sets were not used for the studies of reaction 2. The longrange-corrected functionals LC-BOP-LRD27,28 and ωB97XD329 perform best; CAM-B3LYP-D336,37 is worse. The BPBED3,37−40 PBE0-D3,41,42 and PBE-D339,40,42 functionals without long-range-correction (exhibiting a larger self-interaction error) underestimate ΔG⧧ considerably. Thus, the mechanism of reaction 2 was investigated with the LC-BOP-LRD and ωB97X-D3 functionals, SMD26 hydration, and the tzvp basis set. Mechanism of Reaction 2. Overview. As already shown in Scheme 1, NO+ might attack Co(NH3)5N32+ at the terminal or the bound azide nitrogen. Both attacks can produce a TS or
The experimental33 ΔG⧧ at 25 °C is 103.0 kJ mol−1 based on an assumed transmission coefficient (κ) of 1. In the meantime, κ was determined via molecular dynamics simulations to be around 0.01−0.1 for water exchange reactions of 2+ ions34,35 (data for 3+ ions are not available). Hence, for κ = 0.1 and 0.01, the experimental ΔG⧧ of reaction 3 would be 97.2 and 91.5 kJ mol−1, respectively. The transition state (TS) structure with its imaginary mode (Figure 1) shows that reaction 3 proceeds via the Id mechanism. ΔG⧧ calculated with the small sv(p) and svp basis sets is too low (Table 1). Therefore, these B
DOI: 10.1021/acs.inorgchem.6b01915 Inorg. Chem. XXXX, XXX, XXX−XXX
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Inorganic Chemistry intermediate with E or Z configuration. All these pathways were investigated computationally, and the pertinent results are discussed in following subsections. Attack of NO+ at the Terminal N via the E and the Z Isomers. The attack of NO+ at the terminal N via both isomers produced the intermediate Co(NH3)5N23+ in a single reaction (Scheme 2). In the reaction 3 via the E isomer, Co(NH3)5N23+
but still large (Table 2). The substitution of N2 by water (5) is a facile process (Table 2) following the Id mechanism (Figure 4). Table 2. Gibbs Activation (ΔG⧧) and Reaction (ΔG) Energya for the NO+ Attack at the Terminal N of Azide ωB97X-D3 reaction
ΔG⧧
ΔG
3a
161.8
−39.2
a
Scheme 2
3b
a
a
LC-BOP-LRD ΔG⧧
ΔG
161.6
−320.9
4
72.9
−310.3
95.9
−320.9
5
31.6
−81.6
33.3
−81.4
remarks via E isomer, cyclic N2O product via E isomer, linear N2O product via Z isomer, linear N2O product substitution of N2 by H2O (Id)
Units: kJ mol−1
NH3 ligands are omitted.
and N2O were formed to a large extent in the TS Co(NH3)5(E-N2···N2O)3+ ⧧ (Figure 2). In this case, the two functionals ωB97X-D3 and LC-BOP-LRD yielded similar structures, but different imaginary modes. They were responsible for the formation of the cyclic and the linear isomers of N2O. This is the reason why the Gibbs reaction energies (ΔG) of reactions (3a) and (3b) are different, although the Gibbs activation energies (ΔG⧧) are equal (Table 2). In the TS of the Z isomer, Co(NH3)5(Z-N2···N2O)3+ ⧧ (Figure 3), the bond of the terminal N of azide is elongated, and the N···N bond of N2O is formed partially. With both functionals, the linear N2O product was obtained. For this pathway (4), ΔG⧧ is considerably lower,
Figure 3. Structure and imaginary mode (426i cm−1) of the transition state Co(NH3)5(Z-N2···N2O)3+ ⧧ (ωB97X-D3-SMD/tzvp).
Figure 2. Structure and imaginary mode of the transition state Co(NH3)5(E-N2···N2O)3+ ⧧, (a) ωB97X-D3-SMD/tzvp geometry, 575i cm−1, (b) LC-BOP-LRD-SMD/tzvp geometry, 639i cm−1. C
DOI: 10.1021/acs.inorgchem.6b01915 Inorg. Chem. XXXX, XXX, XXX−XXX
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Inorganic Chemistry
Table 3. Gibbs Activation (ΔG⧧) and Reaction (ΔG) Energya for the NO+ Attack at the Bound N of Azide via the E Isomer ωB97X-D3 reaction
a
ΔG
⧧
ΔG
6 7 8 9 10
119.9 55.5 47.4 79.3
15.5 −30.9 −19.0 −318.9 −31.0
11
25.6
−77.5
LC-BOP-LRD ΔG⧧
ΔG
remarks
122.0 46.3 49.0 85.2
24.2 −47.5 −32.7 −326.1 −28.5
27.4
−75.6
NO+ addition N2 elimination N → O isomerization N2 elimination substitution of E-N4O by H2O (Id) substitution of N2O by H2O (Id)
Units: kJ mol−1.
Figure 4. Structure and imaginary mode (71i cm−1) of the transition state Co(NH3)5···(N2)(OH2)3+ ⧧ (ωB97X-D3-SMD/tzvp).
Attack of NO+ at the Bound N via the E Isomer. This pathway involves the largest number of steps (Scheme 3). The TS for NO+ addition (6) to Co(NH3)5N32+ exhibits a marginally higher energy than the intermediate Co(NH3)5[E-N(N2)(NO)]3+ (Figure S1), such that the calculation of a TS was not feasible. The TS for its fragmentation (7) has a high ΔG⧧ (Table 3). Its imaginary mode (Figure 5) indicates that the cyclic N2O isomer (oxadiazole) will be formed in the Co(NH3)5(cyclN2O)3+ intermediate (Figure S2). This fragmentation reaction (7) is not competitive with N → O isomerization (8). Attempts to calculate a TS for E-N4O substitution by water at Co(NH3)5[E-N(N2)(NO)]3+ resulted also in the N → O isomerization TS, Co(NH3)5···[E-N(N2)(NO)]3+ ⧧ (Figure 6). The subsequently formed intermediate Co(NH3)5(E-ON4)3+ (Figure S3) with an O-bound E-N4O ligand fragments readily (9) via the Co(NH3)5(E-ON2···N2)3+ ⧧ TS (Figure 7) to form the O-bonded bent Co(NH3)5ON23+ (Figure S4) intermediate, which undergoes substitution by water (11) rapidly via the Id
Figure 5. Structure and imaginary mode (538i cm−1) of the transition state Co(NH3)5(E-N2O···N2)3+ ⧧ (ωB97X-D3-SMD/tzvp).
mechanism. Substitution of E-N4O by water (10) at Co(NH3)5(E-ON4)3+ is not competitive. The substitutions of E-N4O and N2O by water follow the Id mechanism (Figures 8 and 9).
Scheme 3a
a
NH3 ligands are omitted. D
DOI: 10.1021/acs.inorgchem.6b01915 Inorg. Chem. XXXX, XXX, XXX−XXX
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Inorganic Chemistry
Figure 9. Structure and imaginary mode (60i cm−1) of the transition state Co(NH3)5···(E-ON4)(OH2)3+ ⧧ (ωB97X-D3-SMD/tzvp).
Figure 6. Structure and imaginary mode (119i cm−1) of the transition state Co(NH3)5···[E-N(N2)(NO)]3+ ⧧ (ωB97X-D3-SMD/tzvp).
Figure 7. Structure and imaginary mode (552i cm−1) of the transition state Co(NH3)5(E-ON2···N2)3+ ⧧ (ωB97X-D3-SMD/tzvp). Figure 10. Structure and imaginary mode (239i cm−1) of the transition state Co(NH3)5(Z-N3···NO)3+ ⧧ (ωB97X-D3-SMD/tzvp).
Attack of NO+ at the Bound N via the Z Isomer. This reaction (12) proceeds via a low-lying TS (Figure 10) and leads to the Co(NH3)5(cycl-N4O)3+ intermediate (Figure S5) exhibiting a cyclic N4O (oxatetrazole) ligand (Schemes 4, 5, and Table 4). The TS for N2 elimination (Figure 11) has a slightly higher ΔG⧧ (13). The subsequent substitution of N2O at the Co(NH3)5N2O3+ intermediate (Figure S6) by water via the Id mechanism (Figure 12) is again a facile process (16). The highest ΔG⧧ among the three steps of this pathway is ∼45 kJ mol−1, since the substitution of the oxatetrazole ligand at Co(NH3)5(cycl-N4O)3+ by water (14) via the Id mechanism (Figure 13), and N2O elimination from Co(NH3)5(cycl-N4O)3+ (15) via the Co(NH3)5(cycl-N2···N2O)3+ ⧧ TS (Figure 14) involve considerably higher ΔG⧧ values. Hence, reactions (14) and (15) are not competitive with (13). The pathway with NO+ attack at the bound N of azide via the Z isomer, proceeding via the Co(NH3)5(cycl-N4O)3+ and Co(NH3)5N2O3+ intermediates, requires the lowest ΔG⧧ of all of the investigated mechanisms (Tables 2−4). Hence, reaction 2 most likely involves these two intermediates; the Co(NH3)5N23+ and Co(NH3)5ON23+ intermediates are unlikely to be formed. Lifetime (τ) of the Intermediates. In the investigated pathways (Schemes 2−4), the intermediates Co(NH3)5N23+, Co(NH 3 ) 5 [E-N(N 2 )(NO)] 3 + , Co(NH 3 ) 5 (E-ON 4 ) 3 + ,
Figure 8. Structure and imaginary mode (70i cm−1) of the transition state Co(NH3)5···(ON2)(OH2)3+ ⧧ (ωB97X-D3-SMD/tzvp).
Hence, the most favorable pathway for the attack at the bound N via the E isomer involves the Co(NH3)5[E-N(N2)(NO)]3+ intermediate and its N → O isomerization with a total ΔG⧧ of ∼71 kJ mol−1 (Table 3). The subsequent N2 elimination from the Co(NH3)5(E-ON4)3+ intermediate exhibits a much lower ΔG⧧, and substitution of ON2 by water (via the Id mechanism) is even faster. The highest ΔG⧧ of this pathway is comparable to that of the attack at the terminal N via the Z isomer (Tables 2 and 3). E
DOI: 10.1021/acs.inorgchem.6b01915 Inorg. Chem. XXXX, XXX, XXX−XXX
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Inorganic Chemistry Scheme 4a
a
NH3 ligands are omitted.
Scheme 5a
a
NH3 ligands are omitted, ωB97X-D3-SMD/tzvp data.
previously,43 whereby, for Co(NH3)5(cycl-N4O)3+ and Co(NH3)5(E-ON4)3+, respectively, four and three decomposition reactions were taken into account: the reverse reaction (12), and (13), (14), (15) for Co(NH3)5(cycl-N4O)3+, and the reverse reaction (8), and (9), (10) for Co(NH3)5(E-ON4)3+.
Co(NH3)5ON23+, Co(NH3)5(cycl-N4O)3+, and Co(NH3)5N2O3+ might be formed, whereby Co(NH3)5[E-N(N2)(NO)]3+ is likely to exhibit a very short lifetime (τ) since, as mentioned above, the TS for its formation has a marginally higher energy. The lifetime of the other intermediates was estimated as described F
DOI: 10.1021/acs.inorgchem.6b01915 Inorg. Chem. XXXX, XXX, XXX−XXX
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Inorganic Chemistry Table 4. Gibbs Activation (ΔG⧧) and Reaction (ΔG) Energya for the NO+ Attack at the Bound N of Azide via the Z Isomer ωB97X-D3
ΔG⧧
ΔG
remarks
23.5 21.9 65.5
−21.5 −301.6 −54.4
33.0 43.6 66.3
−31.7 −302.8 −51.8
56.9 45.6
−288.8 −68.8
74.3 44.3
−289.1 −67.7
NO+ addition N2 elimination substitution of cycl-N4O by H2O (Id) N2O elimination substitution of N2O by H2O (Id)
ΔG
12 13 14 15 16 a
LC-BOP-LRD
ΔG
reaction
⧧
Units: kJ mol−1 Figure 13. Structure and imaginary mode (86i cm−1) of the transition state Co(NH3)5···(cycl-N4O)(OH2)3+ ⧧ (ωB97X-D3-SMD/tzvp).
Figure 11. Structure and imaginary mode (517i cm−1) of the transition state Co(NH3)5(cycl-N2O···N2)3+ ⧧ (ωB97X-D3-SMD/tzvp).
Figure 14. Structure and imaginary mode (657i cm−1) of the transition state Co(NH3)5(cycl-N2···N2O)3+ ⧧ (ωB97X-D3-SMD/tzvp).
Table 5. Lifetime (τ) of the Intermediates τ, s ωB97X-D3 Co(NH3)5N23+ Co(NH3)5N2O3+ Co(NH3)5ON23+ Co(NH3)5(cycl-N4O)3+ Co(NH3)5(E-ON4)3+
Figure 12. Structure and imaginary mode (71i cm−1) of the transition state Co(NH3)5···(N2O)(OH2)3+ ⧧ (ωB97X-D3-SMD/tzvp).
5.4 1.6 4.9 1.1 3.2
× × × × ×
−8
10 10−5 10−9 10−9 10−5
LC-BOP-LRD 1.1 9.2 1.0 6.9 6.1
× × × × ×
10−7 10−6 10−8 10−6 10−5
retention of the configuration, and therefore, the Co(NH3)53+ intermediate is unlikely to exist. It should be noted, however, that this conclusion is based on calculations in which the solvent is treated as a polarizable continuum. For a definitive assessment of the substitution mechanism, Id or D, and the existence of the Co(NH3)53+ intermediate, computations with explicit solvent molecules are required.
The product κΓn was approximated by 1. The calculated lifetimes (Table 5) are in the range of 1 ns to 60 μs. Both functionals yielded similar values for each intermediate with the exception of τ for Co(NH3)5(cycl-N4O)3+. This discrepancy is due to the difference in ΔG⧧ of ∼22 kJ mol−1 for reaction (13) (Table 4 and Scheme 4) which, however, is still within the error limits of the computations (10−15 kJ mol−1 for each ΔG⧧). The Co(NH3)5N2O3+ intermediate exhibits a relatively long lifetime of the order of 10 μs in contrast to Co(NH3)5N23+ and Co(NH3)5ON23+ with τ smaller than ∼100 ns. All of these intermediates undergo substitution by water via the Id mechanism with
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SUMMARY Four pathways for the NO+ attack at the azide ligand of Co(NH3)5N32+ were investigated. Attack at the terminal N via the E and the Z isomers of the TSs requires a ΔG⧧ of 162 and 73−96 kJ mol−1, respectively. This step is rate-determining; G
DOI: 10.1021/acs.inorgchem.6b01915 Inorg. Chem. XXXX, XXX, XXX−XXX
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Inorganic Chemistry the subsequent substitution of N2 in the Co(NH3)5N23+ intermediate by water is very fast (Scheme 2 and Table 2). Attack at the coordinated N via the E isomer requires ΔG⧧ of 71 kJ mol−1 for the formation of Co(NH3)5(E-ON4)3+ in the rate-determining step; the subsequent reactions, N2 elimination and substitution of N2O in Co(NH3)5ON23+, are much faster with ΔG⧧ < 50 kJ mol−1 (Scheme 3 and Table 3). The preferred pathway involves the attack at the coordinated N via the Z isomer, whereby the highest ΔG⧧ of these reactions (Schemes 4, 5, and Table 4) is smaller than 50 kJ mol−1. The substitutions of N2, ON2, N2O, E-ON4, and cycl-N4O in their respective intermediates by water follow the Id mechanism with retention of the configuration as in the previously studied cases.9−11 No evidence for the existence of the square-pyramidal pentacoordinated intermediate Co(NH3)53+ was found, but it should be noted that this needs to be corroborated by computations with explicit solvation.
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(8) Lee, K. Y.; Kuchynka, D. J.; Kochi, J. K. Redox Equilibria of the Nitrosonium Cation and of Its Nonbonded Complexes. Inorg. Chem. 1990, 29, 4196−4204. (9) Rotzinger, F. P. Aquation of the Chloro Pentaammine Complexes of Cobalt(III) and Chromium(III): Do the Almost Equal Activation Parameters Arise from a Common Mechanism? Inorg. Chem. 1999, 38, 5730−5733. (10) Rotzinger, F. P.; Benoit, D. M. Mechanism of the S N Isomerization and Aquation of the Thiocyanato Pentaammine Cobalt(III) Ion. Inorg. Chem. 2000, 39, 944−952. (11) Rotzinger, F. P. Treatment of Substitution and Rearrangement Mechanisms of Transition Metal Complexes with Quantum Chemical Methods. Chem. Rev. 2005, 105, 2003−2038. (12) Langford, C. H.; Gray, H. B. Ligand Substitution Processes; W. A. Benjamin, Inc.: New York, 1965. (13) Merbach, A. E. The Elucidation of Solvent Exchange Mechanisms by High-Pressure NMR Studies. Pure Appl. Chem. 1982, 54, 1479−1493. (14) Merbach, A. E. Use of High Pressure Kinetic Studies in Determining Inorganic Substitution Mechanisms. Pure Appl. Chem. 1987, 59, 161−172. (15) Rotzinger, F. P. Kinetics of Base Hydrolysis of (Nitrato)pentaamminecobalt(III): Stability and Reactivity of Its Ion Pairs with Perchlorate and Azide. Inorg. Chem. 1988, 27, 768−771. (16) Rotzinger, F. P. Base Hydrolysis of Pentaammine Complexes of Cobalt(III): Structure, Reactivity, and Lifetime of the Intermediates. Inorg. Chem. 1988, 27, 772−776. (17) Rotzinger, F. P. Base Hydrolysis of Acidato Pentakis(methylamine) Complexes of Cobalt(III): Evidence for the Pentacoordinated Intermediate Co(NH2CH3)4(NHCH3)2+ Exhibiting a Lifetime of ≈ 1 ns. Inorg. Chem. 1991, 30, 2763−2772. (18) Curchod, B. F. E.; Rotzinger, F. P. The Cause for Tremendous Acceleration of Chloride Substitution via Base Catalysis in the Chloro Pentaammine Cobalt(III) Ion. Inorg. Chem. 2011, 50, 8728−8740. (19) Schmidt, M. W.; Baldridge, K. K.; Boatz, J. A.; Elbert, S. T.; Gordon, M. S.; Jensen, J. H.; Koseki, S.; Matsunaga, N.; Nguyen, K. A.; Su, S. J.; Windus, T. L.; Dupuis, M.; Montgomery, J. A. General Atomic and Molecular Electronic Structure System. J. Comput. Chem. 1993, 14, 1347−1363. (20) Gordon, M. S.; Schmidt, M. W. In Theory and Applications of Computational Chemistry: The First Forty Years; Dykstra, C. E., Frenking, G., Kim, K. S., Scuseria, G. E., Eds.; Elsevier: Amsterdam, The Netherlands, 2005; pp 1167−1189. (21) Schäfer, A.; Horn, H.; Ahlrichs, R. Fully Optimized Contracted Gaussian Basis Sets for Atoms Li to Kr. J. Chem. Phys. 1992, 97, 2571− 2577. (22) Schäfer, A.; Huber, C.; Ahlrichs, R. Fully Optimized Contracted Gaussian Basis Sets of Triple Zeta Valence Quality for Atoms Li to Kr. J. Chem. Phys. 1994, 100, 5829−5835. (23) Weigend, F.; Ahlrichs, R. Balanced Basis Sets of Split Valence, Triple Zeta Valence and Quadruple Zeta Valence Quality for H to Rn: Design and Assessment of Accuracy. Phys. Chem. Chem. Phys. 2005, 7, 3297−3305. (24) Rotzinger, F. P. Structure and Properties of the Precursor/ Successor Complex and Transition State of the CrCl2+/Cr2+ Electron Self-Exchange Reaction via the Inner-Sphere Pathway. Inorg. Chem. 2014, 53, 9923−9931. (25) Bode, B. M.; Gordon, M. S. Macmolplt: a Graphical User Interface for GAMESS. J. Mol. Graphics Modell. 1998, 16, 133−138. (26) Marenich, A. V.; Cramer, C. J.; Truhlar, D. G. Universal Solvation Model Based on Solute Electron Density and on a Continuum Model of the Solvent Defined by the Bulk Dielectric Constant and Atomic Surface Tensions. J. Phys. Chem. B 2009, 113, 6378−6396. (27) Sato, T.; Nakai, H. Density Functional Method Including Weak Interactions: Dispersion Coefficients Based on the Local Response Approximation. J. Chem. Phys. 2009, 131, 224104.
ASSOCIATED CONTENT
S Supporting Information *
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.6b01915. sv(p), svp, and tzvp basis sets for Co and N; atomic coordinates (ωB97X-D3-SMD/tzvp level) of all of the Co complexes; and figures of intermediates (PDF)
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AUTHOR INFORMATION
Corresponding Author
*E-mail: francois.rotzinger@epfl.ch. ORCID
François P. Rotzinger: 0000-0001-8759-4427 Notes
The author declares no competing financial interest.
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ACKNOWLEDGMENTS Prof. J.-D. Chai’s advice for testing the ωB97X-D3 functional is gratefully acknowledged. REFERENCES
(1) Haim, A.; Taube, H. Formation of Co(NH3)5X+2 Complexes by the Reaction of Co(NH3)5N3+2 with HNO2 in the Presence of Various Anions: the Mechanism of Substitution Reactions of Pentaamminecobalt(III) Complexes. Inorg. Chem. 1963, 2, 1199−1203. (2) Buckingham, D. A.; Olsen, I. I.; Sargeson, A. M.; Satrapa, H. The Mechanism of Substitution Reactions of Pentaamminecobalt(III) Complexes. Product Distributions in the Induced Aquation of Some [Co(NH3)5X]2+ Ions in the Presence of Added Anions. Inorg. Chem. 1967, 6, 1027−1032. (3) Reynolds, W. L.; Hafezi, S.; Kessler, A.; Holly, S. Intermediates in Assisted-Aquation Reactions of Ligandopentaamminecobalt(III) Complexes. Inorg. Chem. 1979, 18, 2860−2863. (4) Jackson, W. G.; Lawrance, G. A.; Sargeson, A. M. Mechanism of Hydrolysis of Substituted Cobalt(III)-Amine Complexes: Pentacoordinate Intermediates? Inorg. Chem. 1980, 19, 1001−1005. (5) Buckingham, D. A.; Clark, C. R.; Webley, W. S. Importance of Ion Association in the Induced Reactions of Cobalt(III)-Acido Complexes. 2. Nitrosation of the (NH3)5CoN32+ Ion. Inorg. Chem. 1982, 21, 3353−3360. (6) Jackson, W. G.; Dutton, B. H. Rate Law and Product Distribution for the Nitrosation of (NH3)5CoN32+ Revisited. Inorg. Chem. 1989, 28, 525−531. (7) Stanbury, D. M. Reduction Potentials Involving Inorganic Free Radicals in Aqueous Solution. Adv. Inorg. Chem. 1989, 33, 69−138. H
DOI: 10.1021/acs.inorgchem.6b01915 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry (28) Sato, T.; Nakai, H. Local Response Dispersion Method. II. Generalized Multicenter Interactions. J. Chem. Phys. 2010, 133, 194101. (29) Lin, Y.-S.; Li, G.-D.; Chai, J.-D.; Mao, S.-P. Long-Range Corrected Hybrid Density Functionals with Improved Dispersion Corrections. J. Chem. Theory Comput. 2013, 9, 263−272. (30) Miller, W. H.; Handy, N. C.; Adams, J. E. Reaction Path Hamiltonian for Polyatomic Molecules. J. Chem. Phys. 1980, 72, 99− 112. (31) Pliego, J. R., Jr.; Riveros, J. M. The Cluster−Continuum Model for the Calculation of the Solvation Free Energy of Ionic Species. J. Phys. Chem. A 2001, 105, 7241−7247. (32) Prlj, A.; Rotzinger, F. P. Investigation of the Water Exchange Mechanism of the Plutonyl(VI) and Uranyl(VI) Ions with Quantum Chemical Methods. J. Coord. Chem. 2015, 68, 3328−3339. (33) Hunt, H. R.; Taube, H. Effect of Temperature, Pressure, Acidity and Solvent on an Aquo Ion Exchange Reaction. J. Am. Chem. Soc. 1958, 80, 2642−2646. (34) Kerisit, S.; Liu, C. Structure, Kinetics, and Thermodynamics of the Aqueous Uranyl(VI) Cation. J. Phys. Chem. A 2013, 117, 6421− 6432. (35) Dang, L. X. Computational Studies of Water-Exchange Rates around Aqueous Mg2+ and Be2+. J. Phys. Chem. C 2014, 118, 29028− 29033. (36) Yanai, T.; Tew, D. P.; Handy, N. C. A new Hybrid Exchange− Correlation Functional using the Coulomb-Attenuating Method (CAM-B3LYP). Chem. Phys. Lett. 2004, 393, 51−57. (37) Goerigk, L.; Grimme, S. A Thorough Benchmark of Density Functional Methods for General Main Group Thermochemistry, Kinetics, and Noncovalent Interactions. Phys. Chem. Chem. Phys. 2011, 13, 6670−6688. (38) Becke, A. D. Density-Functional Exchange-Energy Approximation with Correct Asymptotic Behavior. Phys. Rev. A: At., Mol., Opt. Phys. 1988, 38, 3098−3100. (39) Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 1996, 77, 3865−3868. (40) Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized Gradient Approximation Made Simple [Phys. Rev. Lett. 77, 3865 (1996)]. Phys. Rev. Lett. 1997, 78, 1396. (41) Adamo, C.; Barone, V. Toward Reliable Density Functional Methods without Adjustable Parameters: The PBE0 Model. J. Chem. Phys. 1999, 110, 6158−6170. (42) Grimme, S.; Antony, J.; Ehrlich, S.; Krieg, H. A Consistent and Accurate ab Initio Parametrization of Density Functional Dispersion Correction (DFT-D) for the 94 Elements H-Pu. J. Chem. Phys. 2010, 132, 154104. (43) Rotzinger, F. P. The Water-Exchange Mechanism of the [UO2(OH2)5]2+ Ion Revisited: The Importance of a Proper Treatment of Electron Correlation. Chem. - Eur. J. 2007, 13, 800−811.
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DOI: 10.1021/acs.inorgchem.6b01915 Inorg. Chem. XXXX, XXX, XXX−XXX
