4th EucheMs chemistry congress

wednesday, 29-Aug 2012
s690
chem. Listy 106, s587–s1425 (2012)
inorganic Chemistry plus Young inorganic chemistry day
symposium on Co2 chemistry – i
o - 3 0 8
unPreCedented ALKyLzinC CArBonAte viA
Bio-inSPired route invoLvinG rznoh And Co2 K. SoKoLowSKi 1 , w. Bury 2 , i. JuStyniAK 1 ,
M. woLSKA 2 , K. SoLtyS 1 , A. CieSLAK 2 , J. LewinSKi 1
1 Institute of Physical Chemistry, Department of Physical
Chemistry of Supramolecular Complexes, Warsaw, Poland
2 Warsaw Univeristy of Technology, Faculty of Chemistry,
Warsaw, Poland
Over the last decade, bio-fixation approaches for the CO2 sequestration have received much attention because of their great
environmental significance as well as very promising practical
applications in materials chemistry. [1] This bio-inspired solution
for chemical activation of CO is mostly based on ZnOH type
2
reaction systems patterned on active centre of carbonic anhydrase
(CA). [2] However, despite numerous inorganic complexes
investigated as CA mimics, the organozinc RZnOH compounds
have not yet been investigated in this context.
Here we report on the activation of CO by the model
2
alkylzinc hydroxide [3] ( tBuZnOH) (1) in the absence and presence
6
of tBu Zn as proton acceptor, and the isolation of the
2
unprecedented dodecanuclear alkylzinc carbonate [( tBuZn) (µ - 2 5
-CO )] cluster (2). Compound 2 was fully characterized in the
3 6
solid state by X-ray diffraction studies and the presence of the
carbonate group is substantiated by CP-MAS 13C NMR and IR
spectroscopy. The 1H NMR spectroscopic studies clearly indicate
that the presence of an excess of tBu Zn in the 1/CO reaction
2 2
system greatly accelerates the proton transfer from an
intermediate Zn(HCO ) bicarbonate and significantly improves
3
the reaction yield. Moreover, the existence of the reactive
M-C bond in the reported complexes is a unique feature qualifying
these systems for further post-synthetic modification in order to
design of a new class of carbonate secondary building blocks for
materials chemistry. Further biologically inspired studies on the
reactivity of organozinc Zn–OH systems supported by organic
ligands towards effective CO bio-fixation and other small
2
molecules are in progress.
references:
1. J. R. Long et al., Angew. Chem. Int. Ed., 2010, 49,
6058–6082.
2. G. M. Whitesides et al., Chem. Rev., 2008, 108, 946–1051.
3. W. Bury, E. Krajewska, M. Dutkiewicz, K. Sokolowski,
I. Justyniak, Z. Kaszkur, K. J. Kurzydlowski, T. Plocinski
and J. Lewinski, Chem. Commun., 2011, 47, 5467–5469.
Keywords: carbon dioxide; bio-fixation; zinc hydroxide; zinc
alkyls; proton acceptor;
symposium on Co2 chemistry – i
o - 3 0 9
MeChAniStiC inSiGht froM ACtivAtion
PArAMeterS for the reACtion of A
rutheniuM hydride CoMPLex with CArBon
dioxide in ConventionAL SoLventS And An
ioniC Liquid
S. Kern 1 , r. vAn eLdiK 1
1 Friedrich-Alexander-University Erlangen-Nuremberg,
Department of Chemistry and Pharmacy, Erlangen, Germany
The reduction of carbon dioxide to a useable resource (fuel
or otherwise) is a major goal in current chemical research. One
possible way would be to use a hydride transfer reaction by which
CO will first be reduced to formic acid. The reaction rate of the
2
reaction of a ruthenium hydride complex (RuII (terpy)(bpy)H] +
(terpy = 2,2',6',2''-terpyridine; bpy = 2,2'-bipyridine) with
CO 2
4 th EucheMs chemistry congress
to form a formate adduct strongly depends on
the solvent [1] . Detailed kinetic studies in conventional
solvents (water, methanol and ethanol) and in the ionic liquid
[emim][NTf ] ([emim] = 1-ethyl-3-methyl-imidazolium;
2
[NTf ] = bistrifluoromethylsulfonylamide) using stopped-flow
2
methods were performed and second-order rate constants and
activation parameters (ΔH # , ΔS # and ΔV # ) were determined for
the reaction in all solvents. The second-order rate constants
correlate with the acceptor number of the solvent, whereas the
activation parameters support the nature of the insertion
mechanism of the reaction. The results in water, especially the
activation entropy (+14 ± 2 J K-1 mol-1 ) and activation volume
(-5.9 ± 0.6 cm3 mol-1 ), differ significantly from those found for
the other solvents, underlining the importance of hydrogen bond
formation in the transition state.
references:
1. a) Konno H.; Kobayashi A.; Sakamoto H.; Fagalde F.;
Katz N. E.; Saitoh H.; Ishitani O.; Inorg. Chim. Acta
2000, 299, 155–163
b) Creutz C.; Chou M. H. J. Am. Chem. Soc. 2007, 129,
10108-10109
Keywords: reaction mechanisms; kinetics; insertion; carbon
dioxide;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc