First Principles DFT Studies of Metal-Based Biological and Biomimetic Systems - Metallic Systems: A Quantum Chemist's Perspective - page 7

i-Pr

N
N

N
N

TPIH

HIPT

i-Pr Mo

HIPT= i-Pr

N

TPIH

N Mo

i-Pr

N

N

Na

i-Pr

i-Pr

(A) (B) (C)

NH 3

N 2

Mo

1

Mo-NH 3 Mo-N 2

2

+c -

14

+H +

Mo-NH 3 1+ Mo-NNH 1+

13 3

+H +

+

NH

Mo-NH 2 NH 2

TPIH
TPIH

TPIH

HIPT

12 N HIPT

+e -

N

N

N

N

Mo TPIH

N Mo

Mo-NH 2 1+

N

N

+H + N

N

11

+H +

Step II

Mo-NH

Mo-NNH 2

Step I

6

+H +

TPIH +

TPIH

Mo-NNH 2

HIPT
N

HIPT

NH N

7

N
N

N
N

+e -

N Mo TPIH Mo TPIH

N

+H +

N

NH 3

(D)

FIGURE 1.1 (A).Experimental.catalyst.and.(B).theoretical.model..(C).Proton.source,.LutH + ..
(D).Reactions. I .and. II .from.the.putative.nitrogen.ixation.cycle..(Reprinted.with.permission.
from. Alessandra. Magistrato. et. al.,. J. Chem. Theory Comput .,. 3(5),. 1708.. Copyright. 2007.
American.Chemical.Society.)

TABLE 1.1
Reaction Energies in Solution (ΔE R , kcal/mol) of Step I and Step II:
DFT vs. Experimental Results

DFT Expt.

C 6 H 6 C 7 H 16 C 6 H 6

B3LYP
(PCM) a

B3LYP
(PCM) b

BH&H a,d BH&H c,d BH&H a,d BH&H c,d

Step. I −8.7 4.7 2.9 −10.2 −5.3 −4.7 0

Step. II −7.9 6.4 4.6 −13.2 −3.6 −3.0 −1

a. With.6-31+G(d).
b. B3LYP/TZVP,.Ref..125.
c. With.BH&H/6-311++G(d,p).
d. Considering.solvated.LutH + .and.Lut.with.four.solvent.molecules.