TY - JOUR
T1 - Cooperativity in bimetallic dihydroalkoxylation catalysts built on aromatic scaffolds
T2 - Significant rate enhancements with a rigid anthracene scaffold
AU - Ho, Joanne H H
AU - Choy, Sandra W S
AU - MacGregor, Stuart A.
AU - Messerle, Barbara A.
PY - 2011/11/14
Y1 - 2011/11/14
N2 - This work describes investigations into metal-catalyzed sequential reactions using a series of single metal and bimetallic Rh(I) and/or Ir(I) pyrazolyl complexes. Monometallic complexes with bis(1-pyrazolyl)methane (bpm) ligands [M(CO)
2(bpm)]BAr
F
4 (1), bimetallic complexes [M
2(CO)
2(L
scaffold)][BAr
F
4]
2 (2-4) where M = Rh(I) or Ir(I) bearing bitopic ligands L
scaffold = bis(1-pyrazolyl)methane-derived ligands, p-C
6H
4[CH(pz)
2]
2 (L
p), m-C
6H
4[CH(pz)
2]
2 (L
m), and anthracene-bridged 1,8-C
14H
8[CH(pz)
2]
2 (L
Ant), [M
2(CO)
4(L
p)]-[BAr
F
4]
2 (2), [M
2(CO)
4(L
m)][BAr
F
4]
2 (3), and [M
2(CO)
4(L
Ant)][BAr
F
4]
2 (4) were used as catalysts. The efficiency of the complexes as catalysts was tested for the dihydroalkoxylation of a series of alkyne diol substrates, 2-(6-hydroxyhex-1-ynyl)benzyl alcohol (5), 1-methyl-3-heptyne-1,7-diol (6), 2-(5-hydroxypent-1-ynyl)benzyl alcohol (7), and 2-(4-hydroxybut-1-ynyl)benzyl alcohol (8), forming spiroketals. All complexes tested were highly effective catalysts for the intramolecular dihydroalkoxylation reaction. The homobimetallic complexes 2-4 showed significant enhancement in activity and selectivity relative to the single metal catalysts (1). The order of catalytic activity of the bimetallic complexes was found to be [M
2(CO)
4(L
Ant)][BAr
F
4]
2 > [M
2(CO)
4(L
m)][BAr
F
4]
2 > [M
2(CO)
4(L
p)][BAr
F
4]
2 for all substrates, and the bimetallic cooperativity index was established for each reaction.
AB - This work describes investigations into metal-catalyzed sequential reactions using a series of single metal and bimetallic Rh(I) and/or Ir(I) pyrazolyl complexes. Monometallic complexes with bis(1-pyrazolyl)methane (bpm) ligands [M(CO)
2(bpm)]BAr
F
4 (1), bimetallic complexes [M
2(CO)
2(L
scaffold)][BAr
F
4]
2 (2-4) where M = Rh(I) or Ir(I) bearing bitopic ligands L
scaffold = bis(1-pyrazolyl)methane-derived ligands, p-C
6H
4[CH(pz)
2]
2 (L
p), m-C
6H
4[CH(pz)
2]
2 (L
m), and anthracene-bridged 1,8-C
14H
8[CH(pz)
2]
2 (L
Ant), [M
2(CO)
4(L
p)]-[BAr
F
4]
2 (2), [M
2(CO)
4(L
m)][BAr
F
4]
2 (3), and [M
2(CO)
4(L
Ant)][BAr
F
4]
2 (4) were used as catalysts. The efficiency of the complexes as catalysts was tested for the dihydroalkoxylation of a series of alkyne diol substrates, 2-(6-hydroxyhex-1-ynyl)benzyl alcohol (5), 1-methyl-3-heptyne-1,7-diol (6), 2-(5-hydroxypent-1-ynyl)benzyl alcohol (7), and 2-(4-hydroxybut-1-ynyl)benzyl alcohol (8), forming spiroketals. All complexes tested were highly effective catalysts for the intramolecular dihydroalkoxylation reaction. The homobimetallic complexes 2-4 showed significant enhancement in activity and selectivity relative to the single metal catalysts (1). The order of catalytic activity of the bimetallic complexes was found to be [M
2(CO)
4(L
Ant)][BAr
F
4]
2 > [M
2(CO)
4(L
m)][BAr
F
4]
2 > [M
2(CO)
4(L
p)][BAr
F
4]
2 for all substrates, and the bimetallic cooperativity index was established for each reaction.
UR - http://www.scopus.com/inward/record.url?scp=80755187934&partnerID=8YFLogxK
U2 - 10.1021/om2007826
DO - 10.1021/om2007826
M3 - Article
AN - SCOPUS:80755187934
VL - 30
SP - 5978
EP - 5984
JO - Organometallics
JF - Organometallics
SN - 0276-7333
IS - 21
ER -