Mechanisms in Metal Amidoboranes

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1 Electronic Supplementary Information Rules and Trends of Metal Cation Driven Hydride-Transfer Mechanisms in Metal Amidoboranes Dong Young Kim, Han Myoung Lee, Jongcheol Seo, Seung Koo Shin and Kwang S. Kim * Department of Chemistry, Pohang University of Science and Technology Pohang, (Republic of Korea) *: im@postech.ac.r Contents page H 2 -loss pathways from dimeric M(NH 2 BH 3 ) Fig. S1 Systematic increase of the activation energies in the H-steps Fig. S2 Resonance (M N B=N M M N=B N M) hybrid bonds Kinetic scheme of the O/D-pathway Fig. S3 Microcanonical rate-energy curve at 0 K Thermal rate constants of cat1 / cat1 / cat2 (in s 1 ) Relative energies along the reaction pathways. S1 S2 S3 S4 S5 S6 S8 S0

2 H 2 -loss pathways from dimeric M(NH 2 BH 3 ) (Figure 1d, e). H 2 is released by as H δ atom transfer from a boron atom to a H δ+ atom bonded to a nitrogen atom due to an alali or alaline-earth metal cation with/without oligomerization, denoted as the O/D-pathway. In the O/D-pathway, the metal hydride M H in 2 M is formed in the first reaction step through T1 M (1, 2). ([M I ] + [NH 2 BH 3 ] ) 2 NH 2 BH 2 + H M I + [M I ] + [NH 2 BH 3 ] (1) [M II ] 2+ ([NH 2 BH 3 ] ) 2 NH 2 BH 2 + [H M II ] + [NH 2 BH 3 ] (2) In the O-pathway, the intermolecular N B bond in 2 O forms through T2 O (3, 4). NH 2 BH 2 + H M I + [M I ] + [NH 2 BH 3 ] [M I ] + [NH 2 BH 2 NH 2 BH 3 ] + H M I (3) NH 2 BH 2 + [H M II ] + [NH 2 BH 3 ] [H M II ] + [NH 2 BH 2 NH 2 BH 3 ] (4) Then, first H 2 is released by the ionic recombination of H δ with H δ+ through T2 O H forming 3 O (5, 6). [M I ] + [NH 2 BH 2 NH 2 BH 3 ] + H M I [M I ] + [M I ] + [NH 2 BH 2 NHBH 3 ] 2 + H 2 (5) [H M II ] + [NH 2 BH 2 NH 2 BH 3 ] [M II ] 2+ [NH 2 BH 2 NHBH 3 ] 2 + H 2 (6) Second H 2 also occurs by the formation of M H, T3 O M 4 O M (7, 8), followed by the ionic reaction of the M H δ H δ+ N dihydrogen bond, T4 O H 5 O (9, 10). [M I ] + [M I ] + [NH 2 BH 2 NHBH 3 ] 2 H M I + [M I ] + [NH 2 BHNHBH 3 ] (7) [M II ] 2+ [NH 2 BH 2 NHBH 3 ] 2 [H M II ] + [NH 2 BHNHBH 3 ] (8) H M I + [M I ] + [NH 2 BHNHBH 3 ] [M I ] + [M I ] + [NHBHNHBH 3 ] 2 + H 2 (9) [H M II ] + [NH 2 BHNHBH 3 ] [M II ] 2+ [NHBHNHBH 3 ] 2 + H 2 (10) In the D-pathway, two molar equivalents of H 2 release without oligomerization by the redox reaction of H δ and H δ+ in T2 H 3 (11, 12), by the formation of M H in T3 M 4 M (13, 14), and by the redox reaction of H δ and H δ+ in T4 H 5 (15, 16). NH 2 BH 2 + H M I + [M I ] + [NH 2 BH 3 ] [NHBH 2 ] [M I ] + + [M I ] + [NH 2 BH 3 ] + H 2 (11) NH 2 BH 2 + [H M II ] + [NH 2 BH 3 ] [NHBH 2 ] [M II ] 2+ [NH 2 BH 3 ] + H 2 (12) [NHBH 2 ] [M I ] + + [M I ] + [NH 2 BH 3 ] [NHBH 2 ] [M I ] + + NH 2 BH 2 + H M I (13) [NHBH 2 ] [M II ] 2+ [NH 2 BH 3 ] [NHBH 2 ] [H M II ] + + NH 2 BH 2 (14) [NHBH 2 ] [M I ] + + NH 2 BH 2 + H M I ([NHBH 2 ] [M I ] + ) 2 + H 2 (15) [NHBH 2 ] [H M II ] + + NH 2 BH 2 ([NHBH 2 ] ) 2 [M II ] 2+ + H 2 (16) S1

3 Fig. S1 Systematic increase of the activation energies in the H-steps. Among the H-steps, either T2 H or T4 H leads to the lowest activation barriers, while T2 O H leads to the highest barrier. S2

4 Fig. S2 Resonance (M N B=N M M N=B N M) hybrid bonds in T3 O M, 4 O M, T4 O H and 5 O. S3

5 Kinetic scheme of the O/D-pathway. Applying the steady-state approximation, the rate constants are expressed as follows: cat1 cat 2 cat1 cat C ( 2 + 3) = C 3 4 = ( + )( + + ) ( ) C = 4 5 = = S4

6 Fig. S3 Microcanonical rate-energy curve at 0 K for the H 2 release of a) (K + [NH 2 BH 3 ] ) 2, b) (Na + [NH 2 BH 3 ] ) 2, c) (Li + [NH 2 BH 3 ] ) 2, d) Ca 2+ ([NH 2 BH 3 ] ) 2, e) Mg 2+ ([NH 2 BH 3 ] ) 2, and f) K + Li + ([NH 2 BH 3 ] ) 2. S5

7 Thermal rate constants of cat1 / cat1 / cat2 (in s 1 ). Table S1 Rate constants of cat1 / cat1 / cat2 (in s 1 ) at K of the H 2 -release reaction in (K + [NH 2 BH 3 ] ) 2. T(K) cat1 cat1 cat Table S2 Rate constants of cat1 / cat1 / cat2 (in s 1 ) at K of the H 2 -release reaction in (Na + [NH 2 BH 3 ] ) 2. T(K) cat1 cat1 cat Table S3 Rate constants of cat1 / cat1 / cat2 (in s 1 ) at K of the H 2 -release reaction in (Li + [NH 2 BH 3 ] ) 2. T(K) cat1 cat1 cat Table S4 Rate constants of cat1 / cat1 / cat2 (in s 1 ) at K of the H 2 -release reaction in Ca 2+ ([NH 2 BH 3 ] ) 2. T(K) cat1 cat1 cat S6

8 Table S5 Rate constants of cat1 / cat1 / cat2 (in s 1 ) at K of the H 2 -release reaction in Mg 2+ ([NH 2 BH 3 ] ) 2. T(K) cat1 cat1 cat Table S6 Rate constants of cat1 / cat1 (in s 1 ) at K of the H 2 -release reaction in (Li + [NH 2 BH 2 CH 3 ] ) 2 and K + Li + ([NH 2 BH 3 ] ) 2. (Li + [NH 2 BH 2 CH 3 ] ) 2 K + Li + ([NH 2 BH 3 ] ) 2 T(K) cat1 cat1 cat S7

9 Relative energies along the reaction pathways. Table S7 MP2/ G** relative energies (ΔE) and ZPE-corrected energies (ΔE 0 ) for (K + /Na + /Li + [NH 2 BH 3 ] ) 2 and Ca 2+ /Mg 2+ ([NH 2 BH 3 ] ) 2 along the O-pathway. 1 T1 M 2 M T2 O 2 O T2 O H 3 O T3 O M 4 O M T4 O H 5 O K ΔE ΔE Na ΔE ΔE Li ΔE ΔE Ca ΔE ΔE Mg ΔE ΔE Table S8 MP2/ G** relative energies (ΔE) and ZPE-corrected energies (ΔE 0 ) for (K + /Na + /Li + [NH 2 BH 3 ] ) 2 and Ca 2+ /Mg 2+ ([NH 2 BH 3 ] ) 2 along the D-pathway. T2 H 3 T3 M 4 M T4 H 5 K ΔE ΔE Na ΔE ΔE Li ΔE ΔE Ca ΔE ΔE Mg ΔE ΔE Table S9 MP2/ G** relative energies (ΔE) and ZPE corrected energies (ΔE 0 ) for K + Li + ([NH 2 BH 3 ] ) 2 along the O/D-pathway. 1 T1 M 2 M T2 O 2 O T2 O H 3 O T2 H 3 ΔE ΔE Table S10 MP2/ G** relative energies (ΔE) and ZPE corrected energies (ΔE 0 ) for (Li + [NH 2 BH 2 CH 3 ] ) 2 along the D-pathway. 1 T1 M 2 M T2 H 3 ΔE ΔE S8