Pan European Networks - Horizon 2020 - page 35

sciences and technologies’ COST Action domain and is co-ordinated by
Professor Petra Swiderek of the University of Bremen in Germany.
Further investigation
The comprehensive investigation of oxoanionic noble metal compounds
is a challenging task. This is particularly true when considering the
development of suitably preparative routes to these compounds, which
is of fundamental importance, and is especially true if acids are used
that are not as strong oxidisers as nitric or sulphuric acids.
An interesting example would be methanesulfonic acid CH
3
SO
3
H, which
is the simplest organic derivative of sulphuric acid. This acid is widely
used for electroplating processes, even for noble metals. Furthermore,
this acid plays an increasing role in urban mining, i.e. the recovering of
valuable metals from electronic waste. In contrast to the importance of
this acid, its compounds are only scarcely described.
Very recently, we managed to prepare the first binary noble metal
compound of this acid, namely the palladium methanesulfonate
Pd(CH
3
SO
3
)
2
. Fig. 4 illustrates the cut-off from the chain-type structure
of the palladium(II) methanesulfonate Pd(CH
3
SO
3
)
2
.
Many further oxoanionic compounds need to be discovered. Until now,
with respect to our findings, it can be assumed that fascinating new
and unforeseen properties will be found. Another aim of our future
investigations is to transfer the new preparation methods to other
noble metals.
It is worthwhile to mention that the type of compounds described here
for palladium and platinum are essentially unknown for other noble
metals, namely rhodium, iridium, ruthenium, osmium, as well as gold
and silver. Even for gold, our knowledge is very limited. Developing new
syntheses for novel noble metal compounds that bear interesting and
useful properties is the key aim of the inorganic functional materials
group at the Institute of Chemistry, University of Oldenburg, Germany.
and platinum and other oxoanionic compounds
can be gained, for example Pd(SO
4
) and
Pd(NO
3
)
2
. In contrast to the disulfates, in these
compounds the palladium atoms are in typical
square-planar co-ordination of oxygen atoms.
Nevertheless, also with these oxoanions, no
oxidation states higher than +II have been
observed. On the other hand, for the homologue
platinum no divalent compounds could be
gained up to now with these anions. However,
oxidation to the trivalent state is possible if the
anhydride of nitric acid, N
2
O
5
, is used as the
oxidiser. In this case, the complex nitrate
(NO)
2
[Pt(NO
3
)
6
] is obtained, which shows a Pt
4+
in co-ordination of six monodentate nitrate
groups. Fig. 3 shows the [Pt(NO
3
)
6
]
2−
anion with
octahedral co-ordination of a Pt
4+
ion in the
crystals structure of (NO)
2
[Pt(NO
3
)
6
].
The nitrates of palladium and platinum are
of special interest because they can be used
as precursors for the structuring of the
metals, for example as nanoparticles. This
can be done either by heating or by electron-
beam induced decomposition (EBID). In both
cases, the advantage of nitrates is that there
are only volatile decomposition products
besides the metals.
In particular, the use of nitrates within the EBID
process is a highly interesting topic that is
currently being assessed in the European
Cooperation in Science and Technology (COST)
Action ‘Chemistry for ELectron-Induced
NAnofabrication’, commonly known as CELINA.
CELINA falls under the ‘Chemistry and molecular
Professor Dr Mathias SWickleder
Oldenburg University
B R OW S E
H O R I Z O N
2 0 2 0
H O R I Z O N 2 0 2 0 P R O J E C T S : P O R TA L
I S S U E S I X
35
E X C E L L E N T S C I E N C E
Fig. 4
Fig. 3
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