NOVEL METAL COMPLEX CATALYSTS AND USES THEREOF
The invention relates to novel metal complexes useful as catalysts in redox reactions (such as, hydrogen (H 2 ) production). In particular, the invention provides novel transition metal (e.g., cobalt (Co) or nickel (Ni)) complexes, in which the transition metal is coupled with N,N-Bis(2-pyridinylmethyl)-2,2′-Bipyridine-6-methanamine (DPA-Bpy), 6′-((bis(pyridin-2-ylmethyl)amino)methyl)-N,N-dimethyl-2,2′-bipyridin-6-amine (DPA-ABpy), or a derivative thereof. The invention also relates to a method of producing H 2 from an aqueous solution by using the metal complex as a catalyst. In certain embodiments, the invention provides a metal complex of the formulae as described herein.
1 . A metal complex of formula (I):
[M(G)Y] m (X) n (L) a (I)
wherein
M is a transition metal;
G is N,N-bis(2-pyridinylmethyl)-2,2′-bipyridine-6-methanamine (“DPA-Bpy”) or a derivative thereof;
Y, on each occurrence, independently is a halogen group or a water moiety;
X, on each occurrence, independently is an anion;
m is the number of cations per metal complex;
n is the number of anions per metal complex;
L is absent or a neutral molecule; and
a is the number of neutral molecules per metal complex;
provided that when G is N,N-bis(2-pyridinylmethyl)-2,2′-bipyridine-6-methanamine (“DPA-Bpy”), M is not Ru.
2 . The metal complex of claim 1 , wherein said metal is cobalt.
3 . The metal complex of claim 2 , wherein Y is chloride.
4 . The cobalt complex of claim 3 , wherein a is 0; and X is Cl − .
5 . The cobalt complex of claim 4 , wherein said cobalt complex is Co(DPA-Bpy)Cl 2 .
6 . The cobalt complex of claim 3 , wherein L is (C 1-3 )alkyl-CN, and a is 1.
7 . The cobalt complex of claim 6 , wherein said cobalt complex is [Co(DPA-Bpy)(Cl)]Cl 2 .(CH 3 CN).
8 . The cobalt complex of claim 1 , wherein said cobalt complex is of formula (II)
wherein
M is Co, Ru, Ni, or Fe;
R, on each occurrence, independently is H, (C 1-3 )alkyl, cyano, aryl, benzyl, amino, nitrile, carboxylate, hydroxyl, or ester;
X, on each occurrence, independently is an anion
z is the number of cations per metal complex, and
b is the number of anions per metal complex;
or a salt, solvate or hydrate thereof.
9 . The metal complex of claim 8 , wherein M is Co or Ni.
10 . The metal complex of claim 9 , wherein R are all H, and z is 1.
11 . The metal complex of claim 9 , wherein X is PF 6 − or BF 4 − .
12 . The metal complex of claim 10 , wherein said metal complex is [Co(DPA-Bpy)(OH 2 )](PF 6 ) 3 or [Ni(DPA-ABpy)(OH 2 )](BF 4 ), or a salt, solvate or hydrate thereof.
13 . A metal complex of formula (III):
[M(G)Y] m (X) n (L) a (III)
or a salt, solvate or hydrate thereof;
wherein
M is a transition metal;
G is N,N-bis(2-pyridinylmethyl)-2,2′-bipyridine-6-methanamine (“DPA-Bpy”), 6′-((bis(pyridin-2-ylmethyl)amino)methyl)-N,N-dimethyl-2,2′-bipyridin-6-amine (“DPA-ABpy”), or a derivative thereof;
Y, on each occurrence, independently is absent, a halogen group or a water moiety;
X, on each occurrence, independently is an anion;
m is the number of cations per metal complex;
n is the number of anions per metal complex;
L is absent or a neutral molecule; and
a is the number of neutral molecules per metal complex;
provided that when G is N,N-bis(2-pyridinylmethyl)-2,2′-bipyridine-6-methanamine (“DPA-Bpy”), M is not Ru.
14 . The metal complex of claim 13 , wherein M is Co, Ru, Ni, or Fe.
15 . The metal complex of claim 14 , wherein G is DPA-Bpy or DPA-ABpy.
16 . The metal complex of claim 14 , wherein Y is absent or a water moiety.
17 . The metal complex of claim 14 , wherein X is PF 6 − or BF 4 − .
18 . The metal complex of claim 14 , wherein said metal complex is [Ni(DPA-ABpy)(OH 2 )](BF 4 ) 2 or [Co(DPA-ABpy)](PF 6 ) 2 , or a salt, solvate or hydrate thereof.
19 . A catalyst comprising a metal complex of formula (I) or (III).
20 . A process for producing hydrogen from an aqueous solution comprising a step of adding a catalyst of claim 19 to said aqueous solution.
21 . The process of claim 20 , further comprising a step of carrying out electrolysis on the aqueous solution containing the catalyst.
22 . The process of claim 20 , further comprising a step of carrying out photolysis on the aqueous solution containing the catalyst.
23 . The process of claim 22 , wherein said aqueous solution comprises ascorbic acid.
24 . The process of claim 23 , wherein the aqueous solution containing the catalyst has a pH value at about 3 to 6.
25 . The process of claim 20 , wherein said catalyst comprises [Co(DPA-Bpy)(OH 2 )](PF 6 ) 3 , [Ni(DPA-ABpy)(OH 2 )](BF 4 ), or [Co(DPA-ABpy)](PF 6 ) 2 .