TY - JOUR
T1 - Can the binuclear dinitrogen complex [P2N2]Zr(μ-η2-N2)Zr[P 2N2] activate more than one hydrogen molecule? A theoretical sudy
AU - Basch, Harold
AU - Musaev, Djamaladdin G.
AU - Morokuma, Keiji
PY - 2000/8/21
Y1 - 2000/8/21
N2 - The reaction mechanisms of model complexes[p2n2]Zr(μ-η 2NNH)(μ-H)Zr[p2n2], B1 (A7), [p2n2](H)Zr(μ-η2-NNH)Zr[p 2n2], B11 (A3), [p2n2]Zr(μ-η 2-cis-HNNH)(μ-H)Zr(H)[p2n2], C1 (B3), [p2n2](H)Zr(μ-η2-cis-HNNH)Zr(H)[p 2n2], C4 (B13), [p2n2](H)Zr(μ-η2-trans-HNNH)Zr (H)[p2n2], C7 (B21), where [p2n2] = [(PH3)(NH2)], with molecular hydrogen have been studied using density functional theory and compared with those for [p2n2]Zr(μ-η2-N2)Zr[p 2n2], A1. The addition of a H2 molecule to B1 (A7) (i.e., the addition of the second H2 to A1) takes place with a 19.5 kcal/mol barrier, which is about 2 kcal/mol smaller than that for the first H2 addition Al + H2 → A7 reaction. From B3, product of B1 + H2, the process proceeds via either channel I.a, the reverse reaction B3 → B1 + H2, or/and channel I.b, the dihydrogen elimination B3 → [p2n2]Zr(μ-η2-cis-HNNH)Zr[p 2n2] (A15) + H2, with barriers of 11.7 and 21.5 kcal/mol, respectively. Since addition of the first H2 to A1 is known to occur at laboratory conditions, one predicts that the addition of the H2 to B1 (A7) will also be feasible under proper experimental conditions. Once A15 is produced, reaction leads to [p2n2]Zr(μ-NH)(μ-NH2)(μ-H)Zr[p 2n2] (B8) via formation of [p2n2]Zr(μ-NH)2Zr[p2n 2], A17, which was kinetically unreachable by A1 + H2 because of a very high barrier separating it from A7. Addition of H2 to the intermediate complex B11 (A3) leads to B13, where the N-H bonds are located cis to each other. Subsequently, B13 most likely rearranges to complex B3 and follows the reactions of B3. Addition of the third H2 molecule to A1 is found to be kinetically less favorable than the first two.
AB - The reaction mechanisms of model complexes[p2n2]Zr(μ-η 2NNH)(μ-H)Zr[p2n2], B1 (A7), [p2n2](H)Zr(μ-η2-NNH)Zr[p 2n2], B11 (A3), [p2n2]Zr(μ-η 2-cis-HNNH)(μ-H)Zr(H)[p2n2], C1 (B3), [p2n2](H)Zr(μ-η2-cis-HNNH)Zr(H)[p 2n2], C4 (B13), [p2n2](H)Zr(μ-η2-trans-HNNH)Zr (H)[p2n2], C7 (B21), where [p2n2] = [(PH3)(NH2)], with molecular hydrogen have been studied using density functional theory and compared with those for [p2n2]Zr(μ-η2-N2)Zr[p 2n2], A1. The addition of a H2 molecule to B1 (A7) (i.e., the addition of the second H2 to A1) takes place with a 19.5 kcal/mol barrier, which is about 2 kcal/mol smaller than that for the first H2 addition Al + H2 → A7 reaction. From B3, product of B1 + H2, the process proceeds via either channel I.a, the reverse reaction B3 → B1 + H2, or/and channel I.b, the dihydrogen elimination B3 → [p2n2]Zr(μ-η2-cis-HNNH)Zr[p 2n2] (A15) + H2, with barriers of 11.7 and 21.5 kcal/mol, respectively. Since addition of the first H2 to A1 is known to occur at laboratory conditions, one predicts that the addition of the H2 to B1 (A7) will also be feasible under proper experimental conditions. Once A15 is produced, reaction leads to [p2n2]Zr(μ-NH)(μ-NH2)(μ-H)Zr[p 2n2] (B8) via formation of [p2n2]Zr(μ-NH)2Zr[p2n 2], A17, which was kinetically unreachable by A1 + H2 because of a very high barrier separating it from A7. Addition of H2 to the intermediate complex B11 (A3) leads to B13, where the N-H bonds are located cis to each other. Subsequently, B13 most likely rearranges to complex B3 and follows the reactions of B3. Addition of the third H2 molecule to A1 is found to be kinetically less favorable than the first two.
UR - http://www.scopus.com/inward/record.url?scp=0034248901&partnerID=8YFLogxK
U2 - 10.1021/om000389z
DO - 10.1021/om000389z
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AN - SCOPUS:0034248901
SN - 0276-7333
VL - 19
SP - 3393
EP - 3403
JO - Organometallics
JF - Organometallics
IS - 17
ER -