Compound 2 exists in two Z and E conformations. The relative stabilities are (kJ/mol): (E)-2a (0.0), (E)-2b (0.7), (Z)-2a (3.2), (Z)-2b (6.5).
N-Azido-N-methoxyformamide(E)-2a...(E)-2b. (E)-2a : E = -447.89855, ZPVE = 210.3 kJ/mol; r(C-N1) = , r(N1-O) = , r(N1-N2) = , r(N2-N3) = , r(N3-N4) = 1.134. (E)-2b : E = -447.89805, ZPVE = 209.7 kJ/mol; r(C-N1) = 1.397, r(N1-O) = 1.412, r(N1-N2) = 1.412, r(N2-N3) = 1.270, r(N3-N4) = 1.134. ....(Z)-2a....(Z)-2b. (Z)-2a : E = -447.89719, ZPVE = 209.9 kJ/mol; r(C-N1) = , r(N1-O) = , r(N1-N2) = , r(N2-N3) = , r(N3-N4) = . (Z)-2b : E = -447.89571, ZPVE = 209.3 kJ/mol; r(C-N1) = 1.395, r(N1-O) = 1.393, r(N1-N2) = 1.418, r(N2-N3) = 1.268, r(N3-N4) = 1.156. "Anomeric" stabilization in (Z)-2 comes from nO-s*NN donation. The N1-N2 bond is unusually long and the N1-O bond unusually short. In principal, (Z)-2 could undergo either of two HERONs: a) migration of the methoxy group to give methyl formate + azidonitrene (N4); or b) migration of the azido group to give formylazide and methoxynitrene. Route b) gives stable products but is endothermic by 152 kJ/mol. Route a) is not directly feasible because the azidonitrene is not stable, decomposing without activation to give 2 N2. However, the overall reaction, (Z)-2 --> CHO2Me + 2 N2 is exothermic by 581 kJ/mol. Transition structures for expulsion of N2 from each of the four conformers were located. In order of increasing energy (kJ/mol, relative to (E)-2a): (E)-2a-N2 (22.4); (Z)-2b-N2 (24.7); (Z)-2a-N2 (31.7); (E)-2a-N2 (32.3). The transition structure, (Z)-2b-N2, was located for the expulsion of N2 from (Z)-2b. The activation barrier is 18.2 kJ/mol (with 0.96xZPVE). The reaction is exothermic by 161.5 kJ/mol (without ZPVE) and give the product N-methoxy-N-formylnitrene, 3. Transition Structure (Z)-2b-N2. IRC The transition structure for loss of N2 from (Z)-2b.: E = -447.88643; ZPVE = 203.0 kJ/mol; imaginary frequency = 664i. Erel (to (E)-2a) = 24.7 kJ/mol (with 0.98xZPVE). Structural details: r(C=O) = 1.205, r(C-N1) = 1.404, r(N1-O) = 1.410, r(C-O) = 1.435, r(N1-N2) = 1.310, r(N2-N3) = 1.489, r(N3-N4) = 1.126, a(N2-N3-N4) = 147.5. Transition Structures (E)-2a-N2...(E)-2b-N2 The transition structure for loss of N2 from (E)-2a.: E = -447.88335; ZPVE = 202.5 kJ/mol; imaginary frequency = 674i. Erel (to (E)-2a) = 32.3 kJ/mol (with 0.98xZPVE). The transition structure for loss of N2 from (E)-2b.: E = -447.88708; ZPVE = 202.6 kJ/mol; imaginary frequency = 680i. Erel (to (E)-2a) = 22.6 kJ/mol (with 0.98xZPVE). Transition Structure (Z)-2a-N2 The transition structure for loss of N2 from (Z)-2a.: E = -447.88358; ZPVE = 202.9 kJ/mol; imaginary frequency = 663i. Erel (to (E)-2a) = 32.1 kJ/mol (with 0.98xZPVE). Transition Structures for azide migration (HERON rearrangement) Transition structures, 2_HTS1 and 2_HTS2, were located for the HERON migration of the azide group. The activation barriers are substantially higher than for loss of N2. In order to locate these TSs, it was necessary to initially freeze the N-N distances. However, the structures shown below are fully optimized. It appears that the molecule will lose N2 long before it has enough energy to undergo HERON rearrangement. 2-HTS1and 2-HTS2 The transition structure 2-HTS1 for HERON rearrangement from (Z)-2b.: E = --447.826998; ZPVE = 203.0 kJ/mol; imaginary frequency = 273i. Erel (to (E)-2a) = 180.7 kJ/mol (with 0.98xZPVE). The transition structure 2-HTS2 for HERON rearrangement from (Z)-2a.: E = -447.828178; ZPVE = 203.2 kJ/mol; imaginary frequency = 278i. Erel (to (E)-2a) = 177.8 kJ/mol (with 0.98xZPVE). [ It is worth noting that while the HERON rearrangement of AZMO has a high activation barrier and is endothermic by 152 kJ/mol, the reverse reaction, namely the recombination of methoxynitrene and formyl azide, is hindered by only about 28 kJ/mol. ] Transition Structure for methoxy migration (HERON rearrangement after N2 loss) Transition structure, 2_HMTS1 was located for the HERON migration of the methoxy group. The activation barrier is substantially lower than for HERON migration of azide and involves prior loss of N2. In order to locate this TS, I initially froze the N-N distances and optimized to a TS. At this point, the energy was at +110 kJ/mol relative to (E)-2a. I then froze the TS frame and optimized the loss of N2, and then reoptimized with no constraints to the TS shown below. At the N2 loss step, the energy dropped about 260 kJ/mol. The structure shown below is fully optimized. Optimization to a TS leaving out the loose N2, led to a very similar structure, fmn_hmts1, which corresponds to a HERON-type rearrangement of the N-methoxy-N-methoxyaminonitrene 3. The earlier conclusion, that the molecule will lose N2 long before it has enough energy to undergo HERON rearrangement is upheld. 2-HMTS1..fmn_hmts1 The transition structure 2-HMTS1 for HERON MeO rearrangement from ??: E = -447.95607; ZPVE = 194.1 kJ/mol; imaginary frequency = 183i. Erel (to (E)-2a) = -155.2 kJ/mol (with 0.98xZPVE). The transition structure fmn_hmts1 for HERON MeO rearrangement from N-methoxy-N-methoxyaminonitrene 3: E = -338.430684; ZPVE = 178.2 kJ/mol; imaginary frequency = 182i. Erel (to 3) = 2.8 kJ/mol (with 0.98xZPVE). [Note:N-methoxy-N-methoxyaminonitrene 3 is predicted to be unstable toward further loss of N2. It should decompose before it dimerizes.] Transition Structures for N-acyl rotation Transition structure, 2_rTS1 and 2_rTS2, was located for the rotation about the acyl C-N bond. The activation barrier is 41.1 kJ/mol (without ZPVE). It appears that the molecule will lose N2 long before it has enough energy to undergo rotation about the N-acyl bond. 2-rTS1and 2-rTS2 The transition structure 2-rTS1 for N-acyl C-N1 rotation from (Z)-2.: E = -447.88005; ZPVE = 206.1kJ/mol; imaginary frequency = 76i. Erel (to (Z)-2) = 41.1kJ/mol (without ZPVE), = 37.6 kJ/mol (with 0.96xZPVE). Structural details: r(C=O) = 1.194, r(C-N1) = 1.476, r(N1-O) = 1.438, r(N1-N2) = 1.443, r(N2-N3) = 1.264, r(N3-N4) = 1.138, a(C-N1-O) = 102.0, a(C-N1-N2) = 107.6, a(O-N1-N2) = 109.8. The transition structure 2-rTS2 for N-acyl C-N1 rotation from (E)-2.: E = -447.87801; ZPVE = 206.4kJ/mol; imaginary frequency = 213i. Erel (to (E)-2) = 49.4 kJ/mol (with 0.96xZPVE). Structural details: r(C=O) = 1.198, r(C-N1) = 1.482, r(N1-O) = 1.463, r(N1-N2) = 1.444, r(N2-N3) = 1.270, r(N3-N4) = 1.135, a(C-N1-O) = xxx, a(C-N1-N2) = xxx, a(O-N1-N2) = xxx. N-Methoxy-N-formylaminonitrene, (E,Z)-3 Nitrene after loss of N2 from (E)-2a: E = -338.43311; ZPVE = 181.9 kJ/mol ; PLANAR; Erel for loss of N2 = -161.5 kJ/mol (without ZPVE), = -158 kJ/mol (with 0.98xZPVE). Structural details: r(C=O) = 1.187, r(C-N1) = 1.504, r(N1-O) = 1.541, r(C-O) = 1.414,r(N1-N2) = 1.176, a(C-N1-N2) = 126.8, a(C-N1-O) = 106.3, a(O-N1-N2) = 127.0. (Z)-Formylazide . E = -278.11370; ZPVE = 85.0 kJ/mol; r(C=O) = 1.207, r(C-N1) = 1.420, r(N1-N2) = 1.253, r(N2-N3) = 1.131, a(C-N1-N2) = 114.9, a(N1-N2-N3) = 173.8. Methoxynitrene. E = -169.71944; ZPVE = 111.9 kJ/mol; r(C-O) = 1.527, r)O-N) = 1.24, a(C-O-N) = 117.5. N2 : E = -109.52413; ZPVE = 14.7 kJ/mol N4 (forced linear): E = -218.77466, ZPVE = 164.1 (degenerate imaginary frequencies - bending) 777.7i. Decomposes without activation to 2 N2 - DH = -580.6 kJ/mol (including 0.96xZPVE) Related Publications A. Rauk and S. A. Glover, a Computational Study of Bisheteroatom Substituted Amides - Structure and Stereochemistry, J. Org. Chem., 61, 2337-2345 (1996).
(E)-2a : E = -447.89855, ZPVE = 210.3 kJ/mol; r(C-N1) = , r(N1-O) = , r(N1-N2) = , r(N2-N3) = , r(N3-N4) = 1.134.
(E)-2b : E = -447.89805, ZPVE = 209.7 kJ/mol; r(C-N1) = 1.397, r(N1-O) = 1.412, r(N1-N2) = 1.412, r(N2-N3) = 1.270, r(N3-N4) = 1.134. ....(Z)-2a....(Z)-2b. (Z)-2a : E = -447.89719, ZPVE = 209.9 kJ/mol; r(C-N1) = , r(N1-O) = , r(N1-N2) = , r(N2-N3) = , r(N3-N4) = . (Z)-2b : E = -447.89571, ZPVE = 209.3 kJ/mol; r(C-N1) = 1.395, r(N1-O) = 1.393, r(N1-N2) = 1.418, r(N2-N3) = 1.268, r(N3-N4) = 1.156. "Anomeric" stabilization in (Z)-2 comes from nO-s*NN donation. The N1-N2 bond is unusually long and the N1-O bond unusually short. In principal, (Z)-2 could undergo either of two HERONs: a) migration of the methoxy group to give methyl formate + azidonitrene (N4); or b) migration of the azido group to give formylazide and methoxynitrene. Route b) gives stable products but is endothermic by 152 kJ/mol. Route a) is not directly feasible because the azidonitrene is not stable, decomposing without activation to give 2 N2. However, the overall reaction, (Z)-2 --> CHO2Me + 2 N2 is exothermic by 581 kJ/mol. Transition structures for expulsion of N2 from each of the four conformers were located. In order of increasing energy (kJ/mol, relative to (E)-2a): (E)-2a-N2 (22.4); (Z)-2b-N2 (24.7); (Z)-2a-N2 (31.7); (E)-2a-N2 (32.3). The transition structure, (Z)-2b-N2, was located for the expulsion of N2 from (Z)-2b. The activation barrier is 18.2 kJ/mol (with 0.96xZPVE). The reaction is exothermic by 161.5 kJ/mol (without ZPVE) and give the product N-methoxy-N-formylnitrene, 3. Transition Structure (Z)-2b-N2. IRC The transition structure for loss of N2 from (Z)-2b.: E = -447.88643; ZPVE = 203.0 kJ/mol; imaginary frequency = 664i. Erel (to (E)-2a) = 24.7 kJ/mol (with 0.98xZPVE). Structural details: r(C=O) = 1.205, r(C-N1) = 1.404, r(N1-O) = 1.410, r(C-O) = 1.435, r(N1-N2) = 1.310, r(N2-N3) = 1.489, r(N3-N4) = 1.126, a(N2-N3-N4) = 147.5. Transition Structures (E)-2a-N2...(E)-2b-N2 The transition structure for loss of N2 from (E)-2a.: E = -447.88335; ZPVE = 202.5 kJ/mol; imaginary frequency = 674i. Erel (to (E)-2a) = 32.3 kJ/mol (with 0.98xZPVE). The transition structure for loss of N2 from (E)-2b.: E = -447.88708; ZPVE = 202.6 kJ/mol; imaginary frequency = 680i. Erel (to (E)-2a) = 22.6 kJ/mol (with 0.98xZPVE). Transition Structure (Z)-2a-N2 The transition structure for loss of N2 from (Z)-2a.: E = -447.88358; ZPVE = 202.9 kJ/mol; imaginary frequency = 663i. Erel (to (E)-2a) = 32.1 kJ/mol (with 0.98xZPVE). Transition Structures for azide migration (HERON rearrangement) Transition structures, 2_HTS1 and 2_HTS2, were located for the HERON migration of the azide group. The activation barriers are substantially higher than for loss of N2. In order to locate these TSs, it was necessary to initially freeze the N-N distances. However, the structures shown below are fully optimized. It appears that the molecule will lose N2 long before it has enough energy to undergo HERON rearrangement. 2-HTS1and 2-HTS2 The transition structure 2-HTS1 for HERON rearrangement from (Z)-2b.: E = --447.826998; ZPVE = 203.0 kJ/mol; imaginary frequency = 273i. Erel (to (E)-2a) = 180.7 kJ/mol (with 0.98xZPVE). The transition structure 2-HTS2 for HERON rearrangement from (Z)-2a.: E = -447.828178; ZPVE = 203.2 kJ/mol; imaginary frequency = 278i. Erel (to (E)-2a) = 177.8 kJ/mol (with 0.98xZPVE). [ It is worth noting that while the HERON rearrangement of AZMO has a high activation barrier and is endothermic by 152 kJ/mol, the reverse reaction, namely the recombination of methoxynitrene and formyl azide, is hindered by only about 28 kJ/mol. ] Transition Structure for methoxy migration (HERON rearrangement after N2 loss) Transition structure, 2_HMTS1 was located for the HERON migration of the methoxy group. The activation barrier is substantially lower than for HERON migration of azide and involves prior loss of N2. In order to locate this TS, I initially froze the N-N distances and optimized to a TS. At this point, the energy was at +110 kJ/mol relative to (E)-2a. I then froze the TS frame and optimized the loss of N2, and then reoptimized with no constraints to the TS shown below. At the N2 loss step, the energy dropped about 260 kJ/mol. The structure shown below is fully optimized. Optimization to a TS leaving out the loose N2, led to a very similar structure, fmn_hmts1, which corresponds to a HERON-type rearrangement of the N-methoxy-N-methoxyaminonitrene 3. The earlier conclusion, that the molecule will lose N2 long before it has enough energy to undergo HERON rearrangement is upheld. 2-HMTS1..fmn_hmts1 The transition structure 2-HMTS1 for HERON MeO rearrangement from ??: E = -447.95607; ZPVE = 194.1 kJ/mol; imaginary frequency = 183i. Erel (to (E)-2a) = -155.2 kJ/mol (with 0.98xZPVE). The transition structure fmn_hmts1 for HERON MeO rearrangement from N-methoxy-N-methoxyaminonitrene 3: E = -338.430684; ZPVE = 178.2 kJ/mol; imaginary frequency = 182i. Erel (to 3) = 2.8 kJ/mol (with 0.98xZPVE). [Note:N-methoxy-N-methoxyaminonitrene 3 is predicted to be unstable toward further loss of N2. It should decompose before it dimerizes.] Transition Structures for N-acyl rotation Transition structure, 2_rTS1 and 2_rTS2, was located for the rotation about the acyl C-N bond. The activation barrier is 41.1 kJ/mol (without ZPVE). It appears that the molecule will lose N2 long before it has enough energy to undergo rotation about the N-acyl bond. 2-rTS1and 2-rTS2 The transition structure 2-rTS1 for N-acyl C-N1 rotation from (Z)-2.: E = -447.88005; ZPVE = 206.1kJ/mol; imaginary frequency = 76i. Erel (to (Z)-2) = 41.1kJ/mol (without ZPVE), = 37.6 kJ/mol (with 0.96xZPVE). Structural details: r(C=O) = 1.194, r(C-N1) = 1.476, r(N1-O) = 1.438, r(N1-N2) = 1.443, r(N2-N3) = 1.264, r(N3-N4) = 1.138, a(C-N1-O) = 102.0, a(C-N1-N2) = 107.6, a(O-N1-N2) = 109.8. The transition structure 2-rTS2 for N-acyl C-N1 rotation from (E)-2.: E = -447.87801; ZPVE = 206.4kJ/mol; imaginary frequency = 213i. Erel (to (E)-2) = 49.4 kJ/mol (with 0.96xZPVE). Structural details: r(C=O) = 1.198, r(C-N1) = 1.482, r(N1-O) = 1.463, r(N1-N2) = 1.444, r(N2-N3) = 1.270, r(N3-N4) = 1.135, a(C-N1-O) = xxx, a(C-N1-N2) = xxx, a(O-N1-N2) = xxx. N-Methoxy-N-formylaminonitrene, (E,Z)-3 Nitrene after loss of N2 from (E)-2a: E = -338.43311; ZPVE = 181.9 kJ/mol ; PLANAR; Erel for loss of N2 = -161.5 kJ/mol (without ZPVE), = -158 kJ/mol (with 0.98xZPVE). Structural details: r(C=O) = 1.187, r(C-N1) = 1.504, r(N1-O) = 1.541, r(C-O) = 1.414,r(N1-N2) = 1.176, a(C-N1-N2) = 126.8, a(C-N1-O) = 106.3, a(O-N1-N2) = 127.0. (Z)-Formylazide . E = -278.11370; ZPVE = 85.0 kJ/mol; r(C=O) = 1.207, r(C-N1) = 1.420, r(N1-N2) = 1.253, r(N2-N3) = 1.131, a(C-N1-N2) = 114.9, a(N1-N2-N3) = 173.8. Methoxynitrene. E = -169.71944; ZPVE = 111.9 kJ/mol; r(C-O) = 1.527, r)O-N) = 1.24, a(C-O-N) = 117.5. N2 : E = -109.52413; ZPVE = 14.7 kJ/mol N4 (forced linear): E = -218.77466, ZPVE = 164.1 (degenerate imaginary frequencies - bending) 777.7i. Decomposes without activation to 2 N2 - DH = -580.6 kJ/mol (including 0.96xZPVE) Related Publications A. Rauk and S. A. Glover, a Computational Study of Bisheteroatom Substituted Amides - Structure and Stereochemistry, J. Org. Chem., 61, 2337-2345 (1996).
(Z)-2b : E = -447.89571, ZPVE = 209.3 kJ/mol; r(C-N1) = 1.395, r(N1-O) = 1.393, r(N1-N2) = 1.418, r(N2-N3) = 1.268, r(N3-N4) = 1.156.
"Anomeric" stabilization in (Z)-2 comes from nO-s*NN donation. The N1-N2 bond is unusually long and the N1-O bond unusually short.
In principal, (Z)-2 could undergo either of two HERONs: a) migration of the methoxy group to give methyl formate + azidonitrene (N4); or b) migration of the azido group to give formylazide and methoxynitrene. Route b) gives stable products but is endothermic by 152 kJ/mol. Route a) is not directly feasible because the azidonitrene is not stable, decomposing without activation to give 2 N2. However, the overall reaction, (Z)-2 --> CHO2Me + 2 N2 is exothermic by 581 kJ/mol.
Transition structures for expulsion of N2 from each of the four conformers were located. In order of increasing energy (kJ/mol, relative to (E)-2a): (E)-2a-N2 (22.4); (Z)-2b-N2 (24.7); (Z)-2a-N2 (31.7); (E)-2a-N2 (32.3).
The transition structure, (Z)-2b-N2, was located for the expulsion of N2 from (Z)-2b. The activation barrier is 18.2 kJ/mol (with 0.96xZPVE). The reaction is exothermic by 161.5 kJ/mol (without ZPVE) and give the product N-methoxy-N-formylnitrene, 3.
Transition Structure (Z)-2b-N2. IRC The transition structure for loss of N2 from (Z)-2b.: E = -447.88643; ZPVE = 203.0 kJ/mol; imaginary frequency = 664i. Erel (to (E)-2a) = 24.7 kJ/mol (with 0.98xZPVE). Structural details: r(C=O) = 1.205, r(C-N1) = 1.404, r(N1-O) = 1.410, r(C-O) = 1.435, r(N1-N2) = 1.310, r(N2-N3) = 1.489, r(N3-N4) = 1.126, a(N2-N3-N4) = 147.5. Transition Structures (E)-2a-N2...(E)-2b-N2 The transition structure for loss of N2 from (E)-2a.: E = -447.88335; ZPVE = 202.5 kJ/mol; imaginary frequency = 674i. Erel (to (E)-2a) = 32.3 kJ/mol (with 0.98xZPVE). The transition structure for loss of N2 from (E)-2b.: E = -447.88708; ZPVE = 202.6 kJ/mol; imaginary frequency = 680i. Erel (to (E)-2a) = 22.6 kJ/mol (with 0.98xZPVE). Transition Structure (Z)-2a-N2 The transition structure for loss of N2 from (Z)-2a.: E = -447.88358; ZPVE = 202.9 kJ/mol; imaginary frequency = 663i. Erel (to (E)-2a) = 32.1 kJ/mol (with 0.98xZPVE). Transition Structures for azide migration (HERON rearrangement) Transition structures, 2_HTS1 and 2_HTS2, were located for the HERON migration of the azide group. The activation barriers are substantially higher than for loss of N2. In order to locate these TSs, it was necessary to initially freeze the N-N distances. However, the structures shown below are fully optimized. It appears that the molecule will lose N2 long before it has enough energy to undergo HERON rearrangement. 2-HTS1and 2-HTS2 The transition structure 2-HTS1 for HERON rearrangement from (Z)-2b.: E = --447.826998; ZPVE = 203.0 kJ/mol; imaginary frequency = 273i. Erel (to (E)-2a) = 180.7 kJ/mol (with 0.98xZPVE). The transition structure 2-HTS2 for HERON rearrangement from (Z)-2a.: E = -447.828178; ZPVE = 203.2 kJ/mol; imaginary frequency = 278i. Erel (to (E)-2a) = 177.8 kJ/mol (with 0.98xZPVE). [ It is worth noting that while the HERON rearrangement of AZMO has a high activation barrier and is endothermic by 152 kJ/mol, the reverse reaction, namely the recombination of methoxynitrene and formyl azide, is hindered by only about 28 kJ/mol. ] Transition Structure for methoxy migration (HERON rearrangement after N2 loss) Transition structure, 2_HMTS1 was located for the HERON migration of the methoxy group. The activation barrier is substantially lower than for HERON migration of azide and involves prior loss of N2. In order to locate this TS, I initially froze the N-N distances and optimized to a TS. At this point, the energy was at +110 kJ/mol relative to (E)-2a. I then froze the TS frame and optimized the loss of N2, and then reoptimized with no constraints to the TS shown below. At the N2 loss step, the energy dropped about 260 kJ/mol. The structure shown below is fully optimized. Optimization to a TS leaving out the loose N2, led to a very similar structure, fmn_hmts1, which corresponds to a HERON-type rearrangement of the N-methoxy-N-methoxyaminonitrene 3. The earlier conclusion, that the molecule will lose N2 long before it has enough energy to undergo HERON rearrangement is upheld. 2-HMTS1..fmn_hmts1 The transition structure 2-HMTS1 for HERON MeO rearrangement from ??: E = -447.95607; ZPVE = 194.1 kJ/mol; imaginary frequency = 183i. Erel (to (E)-2a) = -155.2 kJ/mol (with 0.98xZPVE). The transition structure fmn_hmts1 for HERON MeO rearrangement from N-methoxy-N-methoxyaminonitrene 3: E = -338.430684; ZPVE = 178.2 kJ/mol; imaginary frequency = 182i. Erel (to 3) = 2.8 kJ/mol (with 0.98xZPVE). [Note:N-methoxy-N-methoxyaminonitrene 3 is predicted to be unstable toward further loss of N2. It should decompose before it dimerizes.] Transition Structures for N-acyl rotation Transition structure, 2_rTS1 and 2_rTS2, was located for the rotation about the acyl C-N bond. The activation barrier is 41.1 kJ/mol (without ZPVE). It appears that the molecule will lose N2 long before it has enough energy to undergo rotation about the N-acyl bond. 2-rTS1and 2-rTS2 The transition structure 2-rTS1 for N-acyl C-N1 rotation from (Z)-2.: E = -447.88005; ZPVE = 206.1kJ/mol; imaginary frequency = 76i. Erel (to (Z)-2) = 41.1kJ/mol (without ZPVE), = 37.6 kJ/mol (with 0.96xZPVE). Structural details: r(C=O) = 1.194, r(C-N1) = 1.476, r(N1-O) = 1.438, r(N1-N2) = 1.443, r(N2-N3) = 1.264, r(N3-N4) = 1.138, a(C-N1-O) = 102.0, a(C-N1-N2) = 107.6, a(O-N1-N2) = 109.8. The transition structure 2-rTS2 for N-acyl C-N1 rotation from (E)-2.: E = -447.87801; ZPVE = 206.4kJ/mol; imaginary frequency = 213i. Erel (to (E)-2) = 49.4 kJ/mol (with 0.96xZPVE). Structural details: r(C=O) = 1.198, r(C-N1) = 1.482, r(N1-O) = 1.463, r(N1-N2) = 1.444, r(N2-N3) = 1.270, r(N3-N4) = 1.135, a(C-N1-O) = xxx, a(C-N1-N2) = xxx, a(O-N1-N2) = xxx. N-Methoxy-N-formylaminonitrene, (E,Z)-3 Nitrene after loss of N2 from (E)-2a: E = -338.43311; ZPVE = 181.9 kJ/mol ; PLANAR; Erel for loss of N2 = -161.5 kJ/mol (without ZPVE), = -158 kJ/mol (with 0.98xZPVE). Structural details: r(C=O) = 1.187, r(C-N1) = 1.504, r(N1-O) = 1.541, r(C-O) = 1.414,r(N1-N2) = 1.176, a(C-N1-N2) = 126.8, a(C-N1-O) = 106.3, a(O-N1-N2) = 127.0. (Z)-Formylazide . E = -278.11370; ZPVE = 85.0 kJ/mol; r(C=O) = 1.207, r(C-N1) = 1.420, r(N1-N2) = 1.253, r(N2-N3) = 1.131, a(C-N1-N2) = 114.9, a(N1-N2-N3) = 173.8. Methoxynitrene. E = -169.71944; ZPVE = 111.9 kJ/mol; r(C-O) = 1.527, r)O-N) = 1.24, a(C-O-N) = 117.5. N2 : E = -109.52413; ZPVE = 14.7 kJ/mol N4 (forced linear): E = -218.77466, ZPVE = 164.1 (degenerate imaginary frequencies - bending) 777.7i. Decomposes without activation to 2 N2 - DH = -580.6 kJ/mol (including 0.96xZPVE) Related Publications A. Rauk and S. A. Glover, a Computational Study of Bisheteroatom Substituted Amides - Structure and Stereochemistry, J. Org. Chem., 61, 2337-2345 (1996).
The transition structure for loss of N2 from (Z)-2b.: E = -447.88643; ZPVE = 203.0 kJ/mol; imaginary frequency = 664i. Erel (to (E)-2a) = 24.7 kJ/mol (with 0.98xZPVE).
Structural details: r(C=O) = 1.205, r(C-N1) = 1.404, r(N1-O) = 1.410, r(C-O) = 1.435, r(N1-N2) = 1.310, r(N2-N3) = 1.489, r(N3-N4) = 1.126, a(N2-N3-N4) = 147.5.
Transition Structures (E)-2a-N2...(E)-2b-N2 The transition structure for loss of N2 from (E)-2a.: E = -447.88335; ZPVE = 202.5 kJ/mol; imaginary frequency = 674i. Erel (to (E)-2a) = 32.3 kJ/mol (with 0.98xZPVE). The transition structure for loss of N2 from (E)-2b.: E = -447.88708; ZPVE = 202.6 kJ/mol; imaginary frequency = 680i. Erel (to (E)-2a) = 22.6 kJ/mol (with 0.98xZPVE). Transition Structure (Z)-2a-N2 The transition structure for loss of N2 from (Z)-2a.: E = -447.88358; ZPVE = 202.9 kJ/mol; imaginary frequency = 663i. Erel (to (E)-2a) = 32.1 kJ/mol (with 0.98xZPVE). Transition Structures for azide migration (HERON rearrangement) Transition structures, 2_HTS1 and 2_HTS2, were located for the HERON migration of the azide group. The activation barriers are substantially higher than for loss of N2. In order to locate these TSs, it was necessary to initially freeze the N-N distances. However, the structures shown below are fully optimized. It appears that the molecule will lose N2 long before it has enough energy to undergo HERON rearrangement. 2-HTS1and 2-HTS2 The transition structure 2-HTS1 for HERON rearrangement from (Z)-2b.: E = --447.826998; ZPVE = 203.0 kJ/mol; imaginary frequency = 273i. Erel (to (E)-2a) = 180.7 kJ/mol (with 0.98xZPVE). The transition structure 2-HTS2 for HERON rearrangement from (Z)-2a.: E = -447.828178; ZPVE = 203.2 kJ/mol; imaginary frequency = 278i. Erel (to (E)-2a) = 177.8 kJ/mol (with 0.98xZPVE). [ It is worth noting that while the HERON rearrangement of AZMO has a high activation barrier and is endothermic by 152 kJ/mol, the reverse reaction, namely the recombination of methoxynitrene and formyl azide, is hindered by only about 28 kJ/mol. ] Transition Structure for methoxy migration (HERON rearrangement after N2 loss) Transition structure, 2_HMTS1 was located for the HERON migration of the methoxy group. The activation barrier is substantially lower than for HERON migration of azide and involves prior loss of N2. In order to locate this TS, I initially froze the N-N distances and optimized to a TS. At this point, the energy was at +110 kJ/mol relative to (E)-2a. I then froze the TS frame and optimized the loss of N2, and then reoptimized with no constraints to the TS shown below. At the N2 loss step, the energy dropped about 260 kJ/mol. The structure shown below is fully optimized. Optimization to a TS leaving out the loose N2, led to a very similar structure, fmn_hmts1, which corresponds to a HERON-type rearrangement of the N-methoxy-N-methoxyaminonitrene 3. The earlier conclusion, that the molecule will lose N2 long before it has enough energy to undergo HERON rearrangement is upheld. 2-HMTS1..fmn_hmts1 The transition structure 2-HMTS1 for HERON MeO rearrangement from ??: E = -447.95607; ZPVE = 194.1 kJ/mol; imaginary frequency = 183i. Erel (to (E)-2a) = -155.2 kJ/mol (with 0.98xZPVE). The transition structure fmn_hmts1 for HERON MeO rearrangement from N-methoxy-N-methoxyaminonitrene 3: E = -338.430684; ZPVE = 178.2 kJ/mol; imaginary frequency = 182i. Erel (to 3) = 2.8 kJ/mol (with 0.98xZPVE). [Note:N-methoxy-N-methoxyaminonitrene 3 is predicted to be unstable toward further loss of N2. It should decompose before it dimerizes.] Transition Structures for N-acyl rotation Transition structure, 2_rTS1 and 2_rTS2, was located for the rotation about the acyl C-N bond. The activation barrier is 41.1 kJ/mol (without ZPVE). It appears that the molecule will lose N2 long before it has enough energy to undergo rotation about the N-acyl bond. 2-rTS1and 2-rTS2 The transition structure 2-rTS1 for N-acyl C-N1 rotation from (Z)-2.: E = -447.88005; ZPVE = 206.1kJ/mol; imaginary frequency = 76i. Erel (to (Z)-2) = 41.1kJ/mol (without ZPVE), = 37.6 kJ/mol (with 0.96xZPVE). Structural details: r(C=O) = 1.194, r(C-N1) = 1.476, r(N1-O) = 1.438, r(N1-N2) = 1.443, r(N2-N3) = 1.264, r(N3-N4) = 1.138, a(C-N1-O) = 102.0, a(C-N1-N2) = 107.6, a(O-N1-N2) = 109.8. The transition structure 2-rTS2 for N-acyl C-N1 rotation from (E)-2.: E = -447.87801; ZPVE = 206.4kJ/mol; imaginary frequency = 213i. Erel (to (E)-2) = 49.4 kJ/mol (with 0.96xZPVE). Structural details: r(C=O) = 1.198, r(C-N1) = 1.482, r(N1-O) = 1.463, r(N1-N2) = 1.444, r(N2-N3) = 1.270, r(N3-N4) = 1.135, a(C-N1-O) = xxx, a(C-N1-N2) = xxx, a(O-N1-N2) = xxx. N-Methoxy-N-formylaminonitrene, (E,Z)-3 Nitrene after loss of N2 from (E)-2a: E = -338.43311; ZPVE = 181.9 kJ/mol ; PLANAR; Erel for loss of N2 = -161.5 kJ/mol (without ZPVE), = -158 kJ/mol (with 0.98xZPVE). Structural details: r(C=O) = 1.187, r(C-N1) = 1.504, r(N1-O) = 1.541, r(C-O) = 1.414,r(N1-N2) = 1.176, a(C-N1-N2) = 126.8, a(C-N1-O) = 106.3, a(O-N1-N2) = 127.0. (Z)-Formylazide . E = -278.11370; ZPVE = 85.0 kJ/mol; r(C=O) = 1.207, r(C-N1) = 1.420, r(N1-N2) = 1.253, r(N2-N3) = 1.131, a(C-N1-N2) = 114.9, a(N1-N2-N3) = 173.8. Methoxynitrene. E = -169.71944; ZPVE = 111.9 kJ/mol; r(C-O) = 1.527, r)O-N) = 1.24, a(C-O-N) = 117.5. N2 : E = -109.52413; ZPVE = 14.7 kJ/mol N4 (forced linear): E = -218.77466, ZPVE = 164.1 (degenerate imaginary frequencies - bending) 777.7i. Decomposes without activation to 2 N2 - DH = -580.6 kJ/mol (including 0.96xZPVE) Related Publications A. Rauk and S. A. Glover, a Computational Study of Bisheteroatom Substituted Amides - Structure and Stereochemistry, J. Org. Chem., 61, 2337-2345 (1996).
The transition structure for loss of N2 from (E)-2a.: E = -447.88335; ZPVE = 202.5 kJ/mol; imaginary frequency = 674i. Erel (to (E)-2a) = 32.3 kJ/mol (with 0.98xZPVE).
The transition structure for loss of N2 from (E)-2b.: E = -447.88708; ZPVE = 202.6 kJ/mol; imaginary frequency = 680i. Erel (to (E)-2a) = 22.6 kJ/mol (with 0.98xZPVE).
Transition Structure (Z)-2a-N2 The transition structure for loss of N2 from (Z)-2a.: E = -447.88358; ZPVE = 202.9 kJ/mol; imaginary frequency = 663i. Erel (to (E)-2a) = 32.1 kJ/mol (with 0.98xZPVE). Transition Structures for azide migration (HERON rearrangement) Transition structures, 2_HTS1 and 2_HTS2, were located for the HERON migration of the azide group. The activation barriers are substantially higher than for loss of N2. In order to locate these TSs, it was necessary to initially freeze the N-N distances. However, the structures shown below are fully optimized. It appears that the molecule will lose N2 long before it has enough energy to undergo HERON rearrangement. 2-HTS1and 2-HTS2 The transition structure 2-HTS1 for HERON rearrangement from (Z)-2b.: E = --447.826998; ZPVE = 203.0 kJ/mol; imaginary frequency = 273i. Erel (to (E)-2a) = 180.7 kJ/mol (with 0.98xZPVE). The transition structure 2-HTS2 for HERON rearrangement from (Z)-2a.: E = -447.828178; ZPVE = 203.2 kJ/mol; imaginary frequency = 278i. Erel (to (E)-2a) = 177.8 kJ/mol (with 0.98xZPVE). [ It is worth noting that while the HERON rearrangement of AZMO has a high activation barrier and is endothermic by 152 kJ/mol, the reverse reaction, namely the recombination of methoxynitrene and formyl azide, is hindered by only about 28 kJ/mol. ] Transition Structure for methoxy migration (HERON rearrangement after N2 loss) Transition structure, 2_HMTS1 was located for the HERON migration of the methoxy group. The activation barrier is substantially lower than for HERON migration of azide and involves prior loss of N2. In order to locate this TS, I initially froze the N-N distances and optimized to a TS. At this point, the energy was at +110 kJ/mol relative to (E)-2a. I then froze the TS frame and optimized the loss of N2, and then reoptimized with no constraints to the TS shown below. At the N2 loss step, the energy dropped about 260 kJ/mol. The structure shown below is fully optimized. Optimization to a TS leaving out the loose N2, led to a very similar structure, fmn_hmts1, which corresponds to a HERON-type rearrangement of the N-methoxy-N-methoxyaminonitrene 3. The earlier conclusion, that the molecule will lose N2 long before it has enough energy to undergo HERON rearrangement is upheld. 2-HMTS1..fmn_hmts1 The transition structure 2-HMTS1 for HERON MeO rearrangement from ??: E = -447.95607; ZPVE = 194.1 kJ/mol; imaginary frequency = 183i. Erel (to (E)-2a) = -155.2 kJ/mol (with 0.98xZPVE). The transition structure fmn_hmts1 for HERON MeO rearrangement from N-methoxy-N-methoxyaminonitrene 3: E = -338.430684; ZPVE = 178.2 kJ/mol; imaginary frequency = 182i. Erel (to 3) = 2.8 kJ/mol (with 0.98xZPVE). [Note:N-methoxy-N-methoxyaminonitrene 3 is predicted to be unstable toward further loss of N2. It should decompose before it dimerizes.] Transition Structures for N-acyl rotation Transition structure, 2_rTS1 and 2_rTS2, was located for the rotation about the acyl C-N bond. The activation barrier is 41.1 kJ/mol (without ZPVE). It appears that the molecule will lose N2 long before it has enough energy to undergo rotation about the N-acyl bond. 2-rTS1and 2-rTS2 The transition structure 2-rTS1 for N-acyl C-N1 rotation from (Z)-2.: E = -447.88005; ZPVE = 206.1kJ/mol; imaginary frequency = 76i. Erel (to (Z)-2) = 41.1kJ/mol (without ZPVE), = 37.6 kJ/mol (with 0.96xZPVE). Structural details: r(C=O) = 1.194, r(C-N1) = 1.476, r(N1-O) = 1.438, r(N1-N2) = 1.443, r(N2-N3) = 1.264, r(N3-N4) = 1.138, a(C-N1-O) = 102.0, a(C-N1-N2) = 107.6, a(O-N1-N2) = 109.8. The transition structure 2-rTS2 for N-acyl C-N1 rotation from (E)-2.: E = -447.87801; ZPVE = 206.4kJ/mol; imaginary frequency = 213i. Erel (to (E)-2) = 49.4 kJ/mol (with 0.96xZPVE). Structural details: r(C=O) = 1.198, r(C-N1) = 1.482, r(N1-O) = 1.463, r(N1-N2) = 1.444, r(N2-N3) = 1.270, r(N3-N4) = 1.135, a(C-N1-O) = xxx, a(C-N1-N2) = xxx, a(O-N1-N2) = xxx. N-Methoxy-N-formylaminonitrene, (E,Z)-3 Nitrene after loss of N2 from (E)-2a: E = -338.43311; ZPVE = 181.9 kJ/mol ; PLANAR; Erel for loss of N2 = -161.5 kJ/mol (without ZPVE), = -158 kJ/mol (with 0.98xZPVE). Structural details: r(C=O) = 1.187, r(C-N1) = 1.504, r(N1-O) = 1.541, r(C-O) = 1.414,r(N1-N2) = 1.176, a(C-N1-N2) = 126.8, a(C-N1-O) = 106.3, a(O-N1-N2) = 127.0. (Z)-Formylazide . E = -278.11370; ZPVE = 85.0 kJ/mol; r(C=O) = 1.207, r(C-N1) = 1.420, r(N1-N2) = 1.253, r(N2-N3) = 1.131, a(C-N1-N2) = 114.9, a(N1-N2-N3) = 173.8. Methoxynitrene. E = -169.71944; ZPVE = 111.9 kJ/mol; r(C-O) = 1.527, r)O-N) = 1.24, a(C-O-N) = 117.5. N2 : E = -109.52413; ZPVE = 14.7 kJ/mol N4 (forced linear): E = -218.77466, ZPVE = 164.1 (degenerate imaginary frequencies - bending) 777.7i. Decomposes without activation to 2 N2 - DH = -580.6 kJ/mol (including 0.96xZPVE) Related Publications A. Rauk and S. A. Glover, a Computational Study of Bisheteroatom Substituted Amides - Structure and Stereochemistry, J. Org. Chem., 61, 2337-2345 (1996).
The transition structure for loss of N2 from (Z)-2a.: E = -447.88358; ZPVE = 202.9 kJ/mol; imaginary frequency = 663i. Erel (to (E)-2a) = 32.1 kJ/mol (with 0.98xZPVE).
Transition structures, 2_HTS1 and 2_HTS2, were located for the HERON migration of the azide group. The activation barriers are substantially higher than for loss of N2. In order to locate these TSs, it was necessary to initially freeze the N-N distances. However, the structures shown below are fully optimized. It appears that the molecule will lose N2 long before it has enough energy to undergo HERON rearrangement.
2-HTS1and 2-HTS2 The transition structure 2-HTS1 for HERON rearrangement from (Z)-2b.: E = --447.826998; ZPVE = 203.0 kJ/mol; imaginary frequency = 273i. Erel (to (E)-2a) = 180.7 kJ/mol (with 0.98xZPVE). The transition structure 2-HTS2 for HERON rearrangement from (Z)-2a.: E = -447.828178; ZPVE = 203.2 kJ/mol; imaginary frequency = 278i. Erel (to (E)-2a) = 177.8 kJ/mol (with 0.98xZPVE). [ It is worth noting that while the HERON rearrangement of AZMO has a high activation barrier and is endothermic by 152 kJ/mol, the reverse reaction, namely the recombination of methoxynitrene and formyl azide, is hindered by only about 28 kJ/mol. ] Transition Structure for methoxy migration (HERON rearrangement after N2 loss) Transition structure, 2_HMTS1 was located for the HERON migration of the methoxy group. The activation barrier is substantially lower than for HERON migration of azide and involves prior loss of N2. In order to locate this TS, I initially froze the N-N distances and optimized to a TS. At this point, the energy was at +110 kJ/mol relative to (E)-2a. I then froze the TS frame and optimized the loss of N2, and then reoptimized with no constraints to the TS shown below. At the N2 loss step, the energy dropped about 260 kJ/mol. The structure shown below is fully optimized. Optimization to a TS leaving out the loose N2, led to a very similar structure, fmn_hmts1, which corresponds to a HERON-type rearrangement of the N-methoxy-N-methoxyaminonitrene 3. The earlier conclusion, that the molecule will lose N2 long before it has enough energy to undergo HERON rearrangement is upheld. 2-HMTS1..fmn_hmts1 The transition structure 2-HMTS1 for HERON MeO rearrangement from ??: E = -447.95607; ZPVE = 194.1 kJ/mol; imaginary frequency = 183i. Erel (to (E)-2a) = -155.2 kJ/mol (with 0.98xZPVE). The transition structure fmn_hmts1 for HERON MeO rearrangement from N-methoxy-N-methoxyaminonitrene 3: E = -338.430684; ZPVE = 178.2 kJ/mol; imaginary frequency = 182i. Erel (to 3) = 2.8 kJ/mol (with 0.98xZPVE). [Note:N-methoxy-N-methoxyaminonitrene 3 is predicted to be unstable toward further loss of N2. It should decompose before it dimerizes.] Transition Structures for N-acyl rotation Transition structure, 2_rTS1 and 2_rTS2, was located for the rotation about the acyl C-N bond. The activation barrier is 41.1 kJ/mol (without ZPVE). It appears that the molecule will lose N2 long before it has enough energy to undergo rotation about the N-acyl bond. 2-rTS1and 2-rTS2 The transition structure 2-rTS1 for N-acyl C-N1 rotation from (Z)-2.: E = -447.88005; ZPVE = 206.1kJ/mol; imaginary frequency = 76i. Erel (to (Z)-2) = 41.1kJ/mol (without ZPVE), = 37.6 kJ/mol (with 0.96xZPVE). Structural details: r(C=O) = 1.194, r(C-N1) = 1.476, r(N1-O) = 1.438, r(N1-N2) = 1.443, r(N2-N3) = 1.264, r(N3-N4) = 1.138, a(C-N1-O) = 102.0, a(C-N1-N2) = 107.6, a(O-N1-N2) = 109.8. The transition structure 2-rTS2 for N-acyl C-N1 rotation from (E)-2.: E = -447.87801; ZPVE = 206.4kJ/mol; imaginary frequency = 213i. Erel (to (E)-2) = 49.4 kJ/mol (with 0.96xZPVE). Structural details: r(C=O) = 1.198, r(C-N1) = 1.482, r(N1-O) = 1.463, r(N1-N2) = 1.444, r(N2-N3) = 1.270, r(N3-N4) = 1.135, a(C-N1-O) = xxx, a(C-N1-N2) = xxx, a(O-N1-N2) = xxx. N-Methoxy-N-formylaminonitrene, (E,Z)-3 Nitrene after loss of N2 from (E)-2a: E = -338.43311; ZPVE = 181.9 kJ/mol ; PLANAR; Erel for loss of N2 = -161.5 kJ/mol (without ZPVE), = -158 kJ/mol (with 0.98xZPVE). Structural details: r(C=O) = 1.187, r(C-N1) = 1.504, r(N1-O) = 1.541, r(C-O) = 1.414,r(N1-N2) = 1.176, a(C-N1-N2) = 126.8, a(C-N1-O) = 106.3, a(O-N1-N2) = 127.0. (Z)-Formylazide . E = -278.11370; ZPVE = 85.0 kJ/mol; r(C=O) = 1.207, r(C-N1) = 1.420, r(N1-N2) = 1.253, r(N2-N3) = 1.131, a(C-N1-N2) = 114.9, a(N1-N2-N3) = 173.8. Methoxynitrene. E = -169.71944; ZPVE = 111.9 kJ/mol; r(C-O) = 1.527, r)O-N) = 1.24, a(C-O-N) = 117.5. N2 : E = -109.52413; ZPVE = 14.7 kJ/mol N4 (forced linear): E = -218.77466, ZPVE = 164.1 (degenerate imaginary frequencies - bending) 777.7i. Decomposes without activation to 2 N2 - DH = -580.6 kJ/mol (including 0.96xZPVE) Related Publications A. Rauk and S. A. Glover, a Computational Study of Bisheteroatom Substituted Amides - Structure and Stereochemistry, J. Org. Chem., 61, 2337-2345 (1996).
The transition structure 2-HTS1 for HERON rearrangement from (Z)-2b.: E = --447.826998; ZPVE = 203.0 kJ/mol; imaginary frequency = 273i. Erel (to (E)-2a) = 180.7 kJ/mol (with 0.98xZPVE).
The transition structure 2-HTS2 for HERON rearrangement from (Z)-2a.: E = -447.828178; ZPVE = 203.2 kJ/mol; imaginary frequency = 278i. Erel (to (E)-2a) = 177.8 kJ/mol (with 0.98xZPVE).
[ It is worth noting that while the HERON rearrangement of AZMO has a high activation barrier and is endothermic by 152 kJ/mol, the reverse reaction, namely the recombination of methoxynitrene and formyl azide, is hindered by only about 28 kJ/mol. ]
Transition structure, 2_HMTS1 was located for the HERON migration of the methoxy group. The activation barrier is substantially lower than for HERON migration of azide and involves prior loss of N2. In order to locate this TS, I initially froze the N-N distances and optimized to a TS. At this point, the energy was at +110 kJ/mol relative to (E)-2a. I then froze the TS frame and optimized the loss of N2, and then reoptimized with no constraints to the TS shown below. At the N2 loss step, the energy dropped about 260 kJ/mol. The structure shown below is fully optimized. Optimization to a TS leaving out the loose N2, led to a very similar structure, fmn_hmts1, which corresponds to a HERON-type rearrangement of the N-methoxy-N-methoxyaminonitrene 3. The earlier conclusion, that the molecule will lose N2 long before it has enough energy to undergo HERON rearrangement is upheld.
2-HMTS1..fmn_hmts1 The transition structure 2-HMTS1 for HERON MeO rearrangement from ??: E = -447.95607; ZPVE = 194.1 kJ/mol; imaginary frequency = 183i. Erel (to (E)-2a) = -155.2 kJ/mol (with 0.98xZPVE). The transition structure fmn_hmts1 for HERON MeO rearrangement from N-methoxy-N-methoxyaminonitrene 3: E = -338.430684; ZPVE = 178.2 kJ/mol; imaginary frequency = 182i. Erel (to 3) = 2.8 kJ/mol (with 0.98xZPVE). [Note:N-methoxy-N-methoxyaminonitrene 3 is predicted to be unstable toward further loss of N2. It should decompose before it dimerizes.] Transition Structures for N-acyl rotation Transition structure, 2_rTS1 and 2_rTS2, was located for the rotation about the acyl C-N bond. The activation barrier is 41.1 kJ/mol (without ZPVE). It appears that the molecule will lose N2 long before it has enough energy to undergo rotation about the N-acyl bond. 2-rTS1and 2-rTS2 The transition structure 2-rTS1 for N-acyl C-N1 rotation from (Z)-2.: E = -447.88005; ZPVE = 206.1kJ/mol; imaginary frequency = 76i. Erel (to (Z)-2) = 41.1kJ/mol (without ZPVE), = 37.6 kJ/mol (with 0.96xZPVE). Structural details: r(C=O) = 1.194, r(C-N1) = 1.476, r(N1-O) = 1.438, r(N1-N2) = 1.443, r(N2-N3) = 1.264, r(N3-N4) = 1.138, a(C-N1-O) = 102.0, a(C-N1-N2) = 107.6, a(O-N1-N2) = 109.8. The transition structure 2-rTS2 for N-acyl C-N1 rotation from (E)-2.: E = -447.87801; ZPVE = 206.4kJ/mol; imaginary frequency = 213i. Erel (to (E)-2) = 49.4 kJ/mol (with 0.96xZPVE). Structural details: r(C=O) = 1.198, r(C-N1) = 1.482, r(N1-O) = 1.463, r(N1-N2) = 1.444, r(N2-N3) = 1.270, r(N3-N4) = 1.135, a(C-N1-O) = xxx, a(C-N1-N2) = xxx, a(O-N1-N2) = xxx. N-Methoxy-N-formylaminonitrene, (E,Z)-3 Nitrene after loss of N2 from (E)-2a: E = -338.43311; ZPVE = 181.9 kJ/mol ; PLANAR; Erel for loss of N2 = -161.5 kJ/mol (without ZPVE), = -158 kJ/mol (with 0.98xZPVE). Structural details: r(C=O) = 1.187, r(C-N1) = 1.504, r(N1-O) = 1.541, r(C-O) = 1.414,r(N1-N2) = 1.176, a(C-N1-N2) = 126.8, a(C-N1-O) = 106.3, a(O-N1-N2) = 127.0. (Z)-Formylazide . E = -278.11370; ZPVE = 85.0 kJ/mol; r(C=O) = 1.207, r(C-N1) = 1.420, r(N1-N2) = 1.253, r(N2-N3) = 1.131, a(C-N1-N2) = 114.9, a(N1-N2-N3) = 173.8. Methoxynitrene. E = -169.71944; ZPVE = 111.9 kJ/mol; r(C-O) = 1.527, r)O-N) = 1.24, a(C-O-N) = 117.5. N2 : E = -109.52413; ZPVE = 14.7 kJ/mol N4 (forced linear): E = -218.77466, ZPVE = 164.1 (degenerate imaginary frequencies - bending) 777.7i. Decomposes without activation to 2 N2 - DH = -580.6 kJ/mol (including 0.96xZPVE) Related Publications A. Rauk and S. A. Glover, a Computational Study of Bisheteroatom Substituted Amides - Structure and Stereochemistry, J. Org. Chem., 61, 2337-2345 (1996).
The transition structure 2-HMTS1 for HERON MeO rearrangement from ??: E = -447.95607; ZPVE = 194.1 kJ/mol; imaginary frequency = 183i. Erel (to (E)-2a) = -155.2 kJ/mol (with 0.98xZPVE).
The transition structure fmn_hmts1 for HERON MeO rearrangement from N-methoxy-N-methoxyaminonitrene 3: E = -338.430684; ZPVE = 178.2 kJ/mol; imaginary frequency = 182i. Erel (to 3) = 2.8 kJ/mol (with 0.98xZPVE). [Note:N-methoxy-N-methoxyaminonitrene 3 is predicted to be unstable toward further loss of N2. It should decompose before it dimerizes.]
Transition structure, 2_rTS1 and 2_rTS2, was located for the rotation about the acyl C-N bond. The activation barrier is 41.1 kJ/mol (without ZPVE). It appears that the molecule will lose N2 long before it has enough energy to undergo rotation about the N-acyl bond.
2-rTS1and 2-rTS2 The transition structure 2-rTS1 for N-acyl C-N1 rotation from (Z)-2.: E = -447.88005; ZPVE = 206.1kJ/mol; imaginary frequency = 76i. Erel (to (Z)-2) = 41.1kJ/mol (without ZPVE), = 37.6 kJ/mol (with 0.96xZPVE). Structural details: r(C=O) = 1.194, r(C-N1) = 1.476, r(N1-O) = 1.438, r(N1-N2) = 1.443, r(N2-N3) = 1.264, r(N3-N4) = 1.138, a(C-N1-O) = 102.0, a(C-N1-N2) = 107.6, a(O-N1-N2) = 109.8. The transition structure 2-rTS2 for N-acyl C-N1 rotation from (E)-2.: E = -447.87801; ZPVE = 206.4kJ/mol; imaginary frequency = 213i. Erel (to (E)-2) = 49.4 kJ/mol (with 0.96xZPVE). Structural details: r(C=O) = 1.198, r(C-N1) = 1.482, r(N1-O) = 1.463, r(N1-N2) = 1.444, r(N2-N3) = 1.270, r(N3-N4) = 1.135, a(C-N1-O) = xxx, a(C-N1-N2) = xxx, a(O-N1-N2) = xxx. N-Methoxy-N-formylaminonitrene, (E,Z)-3 Nitrene after loss of N2 from (E)-2a: E = -338.43311; ZPVE = 181.9 kJ/mol ; PLANAR; Erel for loss of N2 = -161.5 kJ/mol (without ZPVE), = -158 kJ/mol (with 0.98xZPVE). Structural details: r(C=O) = 1.187, r(C-N1) = 1.504, r(N1-O) = 1.541, r(C-O) = 1.414,r(N1-N2) = 1.176, a(C-N1-N2) = 126.8, a(C-N1-O) = 106.3, a(O-N1-N2) = 127.0. (Z)-Formylazide . E = -278.11370; ZPVE = 85.0 kJ/mol; r(C=O) = 1.207, r(C-N1) = 1.420, r(N1-N2) = 1.253, r(N2-N3) = 1.131, a(C-N1-N2) = 114.9, a(N1-N2-N3) = 173.8. Methoxynitrene. E = -169.71944; ZPVE = 111.9 kJ/mol; r(C-O) = 1.527, r)O-N) = 1.24, a(C-O-N) = 117.5. N2 : E = -109.52413; ZPVE = 14.7 kJ/mol N4 (forced linear): E = -218.77466, ZPVE = 164.1 (degenerate imaginary frequencies - bending) 777.7i. Decomposes without activation to 2 N2 - DH = -580.6 kJ/mol (including 0.96xZPVE) Related Publications A. Rauk and S. A. Glover, a Computational Study of Bisheteroatom Substituted Amides - Structure and Stereochemistry, J. Org. Chem., 61, 2337-2345 (1996).
The transition structure 2-rTS1 for N-acyl C-N1 rotation from (Z)-2.: E = -447.88005; ZPVE = 206.1kJ/mol; imaginary frequency = 76i. Erel (to (Z)-2) = 41.1kJ/mol (without ZPVE), = 37.6 kJ/mol (with 0.96xZPVE).
Structural details: r(C=O) = 1.194, r(C-N1) = 1.476, r(N1-O) = 1.438, r(N1-N2) = 1.443, r(N2-N3) = 1.264, r(N3-N4) = 1.138, a(C-N1-O) = 102.0, a(C-N1-N2) = 107.6, a(O-N1-N2) = 109.8.
The transition structure 2-rTS2 for N-acyl C-N1 rotation from (E)-2.: E = -447.87801; ZPVE = 206.4kJ/mol; imaginary frequency = 213i. Erel (to (E)-2) = 49.4 kJ/mol (with 0.96xZPVE).
Structural details: r(C=O) = 1.198, r(C-N1) = 1.482, r(N1-O) = 1.463, r(N1-N2) = 1.444, r(N2-N3) = 1.270, r(N3-N4) = 1.135, a(C-N1-O) = xxx, a(C-N1-N2) = xxx, a(O-N1-N2) = xxx.
N-Methoxy-N-formylaminonitrene, (E,Z)-3 Nitrene after loss of N2 from (E)-2a: E = -338.43311; ZPVE = 181.9 kJ/mol ; PLANAR; Erel for loss of N2 = -161.5 kJ/mol (without ZPVE), = -158 kJ/mol (with 0.98xZPVE). Structural details: r(C=O) = 1.187, r(C-N1) = 1.504, r(N1-O) = 1.541, r(C-O) = 1.414,r(N1-N2) = 1.176, a(C-N1-N2) = 126.8, a(C-N1-O) = 106.3, a(O-N1-N2) = 127.0. (Z)-Formylazide . E = -278.11370; ZPVE = 85.0 kJ/mol; r(C=O) = 1.207, r(C-N1) = 1.420, r(N1-N2) = 1.253, r(N2-N3) = 1.131, a(C-N1-N2) = 114.9, a(N1-N2-N3) = 173.8. Methoxynitrene. E = -169.71944; ZPVE = 111.9 kJ/mol; r(C-O) = 1.527, r)O-N) = 1.24, a(C-O-N) = 117.5. N2 : E = -109.52413; ZPVE = 14.7 kJ/mol N4 (forced linear): E = -218.77466, ZPVE = 164.1 (degenerate imaginary frequencies - bending) 777.7i. Decomposes without activation to 2 N2 - DH = -580.6 kJ/mol (including 0.96xZPVE) Related Publications A. Rauk and S. A. Glover, a Computational Study of Bisheteroatom Substituted Amides - Structure and Stereochemistry, J. Org. Chem., 61, 2337-2345 (1996).
Nitrene after loss of N2 from (E)-2a: E = -338.43311; ZPVE = 181.9 kJ/mol ; PLANAR; Erel for loss of N2 = -161.5 kJ/mol (without ZPVE), = -158 kJ/mol (with 0.98xZPVE).
Structural details: r(C=O) = 1.187, r(C-N1) = 1.504, r(N1-O) = 1.541, r(C-O) = 1.414,r(N1-N2) = 1.176, a(C-N1-N2) = 126.8, a(C-N1-O) = 106.3, a(O-N1-N2) = 127.0.
(Z)-Formylazide .
E = -278.11370; ZPVE = 85.0 kJ/mol; r(C=O) = 1.207, r(C-N1) = 1.420, r(N1-N2) = 1.253, r(N2-N3) = 1.131, a(C-N1-N2) = 114.9, a(N1-N2-N3) = 173.8.
Methoxynitrene.
E = -169.71944; ZPVE = 111.9 kJ/mol; r(C-O) = 1.527, r)O-N) = 1.24, a(C-O-N) = 117.5.
N2 : E = -109.52413; ZPVE = 14.7 kJ/mol
N4 (forced linear): E = -218.77466, ZPVE = 164.1 (degenerate imaginary frequencies - bending) 777.7i. Decomposes without activation to 2 N2 - DH = -580.6 kJ/mol (including 0.96xZPVE)
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