4th EucheMs chemistry congress

Poster Session 1
s984
chem. Listy 106, s587–s1425 (2012)
Poster session 1 - inorganic Chemistry
P - 0 2 4 6
ChLoride And CArBoxyLAte CoMPLexeS of
GoLd(iii) with n,n-donor LiGAndS
n. AKhMAduLLinA 1 , A. BoriSovA 2 , A. ChurAKov 3 ,
o. ShiShiLov 4 , y. KArGin 1
1 A.A. Baikov Institute of Metallurgy and Material Science of
RAS, Laboratory of physical and chemical analysis of ceramic
materials, Moscow, Russia
2 A.N. Nesmeyanov Institute of Organoelement Compounds of
RAS, Laboratory for X-Ray Diffraction Studies, Moscow,
Russia
3 N.S. Kurnakov Institute of General and Inorganic Chemistry of
RAS, Laboratory for X-Ray Diffraction Studies, Moscow,
Russia
4 N.S. Kurnakov Institute of General and Inorganic Chemistry of
RAS, Laboratory of power-consuming susbtances and
materials, Moscow, Russia
Chemistry of gold complexes is a growing modern area of
coordination chemistry. First of all this is due to broadening use
of gold compounds in homogeneous catalysis. Analysis of
influence of ligands environment is impossible without the
information about structure and reactivity of such compounds
which makes study of new gold chloride and carboxylate
complexes a topical issue.
The general approach to synthesis of gold(III) carboxylate
complexes with N,N-donor ligands (2,2'-bipyridine,
phenanthroline) is a substitution of chloride ligands in complexes
[LAuCl ]X under action of silver carboxylates. The most
2
common-used starting materials are complexes [LAuCl ]Cl. In
2
order to reduce a consumption of silver carboxylates we changed
– inner-sphere chloride ions with BF ions. 4
– Complexes with BF ions were used as starting materials
4
for reaction with silver acetate, trimethylacetate and
trifluoroacetate. The reaction leads to formation of corresponding
carboxylate gold(III) compounds [LAu(RCO ) ]BF . According
2 2 4
to X-ray diffraction and IR-spectroscopy data they are
mononuclear complexes with chelate coordination of N,N-donor
ligands and terminal coordination of two carboxylate groups.
Complexes are quite stable but slowly decompose under the light.
Trifluoroacetates are noticeably less stable than others
carboxylates.
Our attempts to substitute chloride ligands in
[(phen)AuCl ]Cl without use of silver carboxylates gave
2
unexpected result. Reaction of [(phen)AuCl ]Cl with sodium
2
acetate in glacial acetic acid at 80°? leads to essential
rearrangement of gold coordination sphere. A half of
[(phen)AuCl ] 2 + ions lose phenanthroline and join chloride ligands
giving [AuCl ] 4 – anions. The reaction results in formation of
[(phen)AuCl ][AuCl ] complex, which was characterized by
2 4
X-ray diffraction analysis. The quantum-chemical calculations
show that [LAuCl ][AuCl ] are products of thermodynamic
2 4
control in the systems [LAuCl ] 2 + – – –RCO – Cl (calculations were
2
carried out for L = 2,2'-bipyridine, phenanthroline and R = CH , 3
CMe , CF ). 3 3
Acknowledgement: We are grateful to the Council of the
President of the Russian Federation for young scientists for
financial support (project 977.2012.3).
Keywords: gold; chloride; carboxylate; N,N-donor ligands;
4 th EucheMs chemistry congress
P - 0 2 4 7
A BioinSPired, inorGAniC oxyGen evoLvinG
CAtALySt BASed on A MAnGAneSe
PoLyoxovAnAdAte CLuSter
J. forSter 1
1 Friedrich-Alexander-University Erlangen-Nuremberg,
Department of Chemistry Inorganic Chemistry II, Erlangen,
Germany
Here, we present a bioinspired, novel [Mn V O (OAc) ] 4 4 17 3 3cluster
(= {Mn4V4}) which features a central manganese-oxo
cubane [Mn O ] 4 4 6+ core supported by four corner-sharing [VO ] 4
tetrahedra acting as inorganic ‘tripodal’ ligands. The cubane unit
is stabilised by three [VO ] tetrahedra directly, which are
4
connected to the manganese atoms by six bridging V-O-Mn bonds
in total. In addition, three acetate ligands fill the coordination
sphere. Compared with other [Mn O L ] complexes this
4 4 6
[Mn O ]-polyoxovanadate unit is air-stable and easily accessible.
4 4
The four manganese centres were tentatively assigned as
MnIII 2MnIV based on bond valance sum calculations, elemental
2
analysis and ESI-MS. The cyclic voltammogram of the {Mn V } 4 4
cluster in acetonitrile shows three distinct reversible redox waves
(-0,90 V, 0,08 V and 1,07 V) which indicate a highly redox-active
species. ESI-mass spectrometry confirmed the existence of the
{Mn V } cluster in solution.
4 4
This oxygen evolving complex (OEC) model complex is
inspired by nature and an aqueous solution of {Mn V } is capable
4 4
of oxygen evolution in the presence of a stoichiometric oxidant
like cerium ammonium nitrate (CeIV ) or light-driven by a
2- well-known Ru-based system ([Ru(bpy) ]Cl / S O ).
3 2 2 8
Since these are our initial results we have to optimise the
system and to improve the turnover numbers. Furthermore, the
exact redox-reactions of the manganese-oxo core needs to be
investigated. In addition, it has to be shown that the reaction is
indeed homogeneous and does not involve the formation of
heterogeneous particles.
Keywords: Polyoxometalates; Oxygen evolving complex;
Manganese; Vanadates; Oxygen evolution;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc