Dissertation

|3.4 Outlook, Exploratory Investigations and Perspectives|
As described for Ru(bbip),a transformation of the imidazolium salt into the corresponding
carbene derivatives of different metal centers is very important. For the subsequent use as starting
material in the transmetallation reactions, formation of the NHC-silver complex of Ru 2 (edip)
became interesting at this stage. In this context method C2 was applied, using Ag 2 O as base
for the transformation of the imidazolium salt into the corresponding metal-NHC complex (see
figure 123) as discribed for Ru(bbip).
N
N
N
N
Ru 2+
N
N
N
N
N
N
N
N
N
Ru 2+
N
N
N
Ru 2 (edip)
Ag 2 O
method C2
N
N
N
N
Ru 2+
N
N
N
N
Cl
Ag
Cl
Ag
N
N
N
N
N
Ru 2+
N
N
N
Ru 2 (edip)Ag 2
Figure 123: Preparation of the tetranuclear heterobimetallic silver NHC-complex of Ru 2 (edip).
To increase the driving force the chloride salt of Ru 2 (edip) was prepared. Counter ion exchange
of the [PF 6 ]-salt of Ru 2 (edip) with (Bu) 4 NCl in acetone/ethyl acetate gave the corresponding
chloride salt in quantitative yield. The complexation reaction was carried out in dichloromethane.
After stirring Ru 2 (edip) and Ag 2 O in the presence of molecular sieves in dichloromethane for 16
hours, the solids were filtered off and the volatiles were removed from the remaining solution.
Analysis of the remaining solid gave clear evidence for a complete conversion into the
pure product [{(tbbpy) 2 Ru} 2 (µ-edip){AgCl} 2 ]Cl 4 (Ru 2 (edip)Ag 2 ). The disappearance of the
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