A mixed-ligand P,S,N-cis-dioxorhenium(V) complex by ligand exchange reactions on trans-monooxo-trichlorobis(triphenylphosphine)rhenium(V): Formation and structural studies

Article abstract of DOI:10.1016/S0277-5387(98)00169-7

In the course of our efforts to synthesize rhenium(V) complexes for potential use in nuclear medicine, tridentate dithiolate ligands were combined with (dialkylamine) ethylene thiols [HS-(CH₂)₂-NR′₂] (R′=alkyl, alkoxy) to form amine group bearing mixed-ligand complexes [ReO(SNS)(S)]. The reaction of HS-CH₂-CH₂-N-(CH₂-CH₂-N(C ₂H₅)₂)CH₂-CH₂-SH (N,N-bis(2-mercaptoethyl)-N′,N′-diethylethylenediamine, 2, as a tris-chelating ligand and 1,4-dioxa-8-azaspiro-N-2-mercaptoethylene - decane, 3, with the neutral Re(V) complex [ReOCl₃(PPh₃)₂], 1, yields, in addition to the expected square-pyramidal 3+1 compound (1,4dioxa - 8 - azaspiro - N - 2 - thiolatoethylene - -decane)N,N - bis(2-mercaptoethyl)(N′,N′ - di - ethyl - ethylenediamine) oxorhenium(V), 4, the new five-coordinated complex [1,4-dioxa-8-azaspiro-N-2-mercaptoethylene-[4,5]-decane(triphenylphosphinato) dioxorhenium(V)], 5. Being the only product in the absence of the tridentate component, 5 has a trigonal-bipyramidal structure, where the coordination sphere is formed by two oxo groups in an uncommon cis-arrangement, S and N from the aminothiolate and by the phosphorus atom from the phosphine group originating from the precursor molecule. The structure was verified by mass, ¹H NMR, IR spectroscopy as well as by XRD. In addition, extended x-ray absorption spectroscopy (EXAFS) was applied to both the precursor and the resulting compound 5 to compare the complex structures in the solid and the soluted state. Experiments with ¹⁸O labelled water added to the reaction mixture led to ¹⁸O in the dioxo core, showing that water is the origin of the additional oxo group.

Full text of DOI:10.1016/S0277-5387(98)00169-7

Polyhedron Vol[ 06\ No[ 10\ pp[ 2600Ð2619\ 0887
Þ 0887 Elsevier Science Ltd
Pergamon
All rights reserved[ Printed in Great Britain
9166Ð4276:87 ,08[99¦9[99
\
PII] S9166Ð4276"87#99058Ð6
A mixed!ligand P\S\N!cis!dioxorhenium"V#
complex by ligand exchange reactions on
trans!monooxo!
trichlorobis"triphenylphosphine#rhenium"V#]
formation and structural studies
Matthias Friebe\aꢀ Ruediger Jankowsky\a Hartmut Spies\a Wilhelm Seichter\b
Minas Papadopoulos\c Efstratios Chiotellisc and Bernd Johannsena
a Forschungszentrum Rossendorf\ Institut fur Bioanorganische und Radiopharmazeutische Chemie\
Ã
Postfach 409008\ 90203 Dresden\ Germany
b Institut fur Organische Chemie\ TU!Bergakademie Freiberg\ Leipziger Stra)e 18\ 98485 Freiberg\
Ã
Germany
c Institutes of Radioisotopes!Radiodiodiagnostic Products and Material Science\ NCSR {{Demokritos||\
P[O[ Box 59117\ 04209 Ag[ Paraskevi\ Athens\ Greece
"Received 00 February 0887^ accepted 19 April 0887#
Abstract*In the course of our e}orts to synthesize rhenium"V# complexes for potential use in nuclear medicine\
tridentate dithiolate ligands were combined with "dialkylamine# ethylene thiols ðHSÐ"CH1#1ÐNR?1Ł "R?ꢁalkyl\
alkoxy# to form amine group bearing mixed!ligand complexes ðReO"SNS#"S#Ł[ The reaction of HSÐCH1ÐCH1Ð
NÐ"CH1ÐCH1ÐN"C1H4#1#CH1ÐCH1ÐSH "N\N!bis"1!mercaptoethyl#!N?\N?!diethylethylenediamine\ 1\ as a tris!
chelating ligand and 0\3!dioxa!7!azaspiro!N!1!mercaptoethylene!ð3\4Ł!decane\ 2\ with the neutral Re"V#
complex ðReOCl2"PPh2#1Ł\ 0\ yields\ in addition to the expected square!pyramidal {{2¦0|| compound "0\3!
dioxa!7!azaspiro!N!1!thiolatoethylene!ð3\4Ł!decane#N\N!bis"1!mercaptoethyl#"N?\N?!di!ethyl!ethylenediamine#
oxorhenium"V#\ 3\ the new _ve!coordinated complex ð0\3!dioxa!7!azaspiro!N!1!mercaptoethylene!ð3\4Ł!
decane"triphenylphosphinato#dioxorhenium"V#Ł\ 4[ Being the only product in the absence of the tridentate
component\ 4 has a trigonalÐbipyramidal structure\ where the coordination sphere is formed by two oxo
groups in an uncommon cis!arrangement\ S and N from the aminothiolate and by the phosphorus atom from
the phosphine group originating from the precursor molecule[ The structure was veri_ed by mass\ 0H NMR\
IR spectroscopy as well as by XRD[ In addition\ extended x!ray absorption spectroscopy "EXAFS# was applied
to both the precursor and the resulting compound 4 to compare the complex structures in the solid and the
soluted state[ Experiments with 07 O labelled water added to the reaction mixture led to 07 O in the dioxo core\
showing that water is the origin of the additional oxo group[ Þ 0887 Elsevier Science Ltd[ All rights reserved[
Þ 0887 Elsevier Science Ltd[ All rights reserved
Keywords] rhenium"V# mixed ligand complexes^ cis!dioxo^ trigonalÐbipyramidal^ X!ray structure^ XANES^
EXAFS
———————————————————————————————————————————————
INTRODUCTION
the radioactive nuclides 88 m Tc and 07 5 Re:07 7 Re have in
nuclear medicine[ Our special attention is focused on
the so!called {{2¦0|| mixed!ligand complexes\ a class
of compounds useful for the design of new radiotracer
molecules ð1\ 2Ł\ where the MO2¦ core is coordinated
by both a tridentate and a monodentate ligand[
We were particularly interested in {{2¦0|| com!
There is great interest in the chemistry of technetium
and rhenium ð0Ł because of the high signi_cance that
ꢀ Author to whom correspondence should be addressed[
Fax] ¦38!240!159!2121^ E!mail] friebeÝfz!rossendorf[de[
2600

2601
M[ Friebe et al[
Fig[ 0[ A selection of known oxometal"V# complexes as the results of ligand exchange reactions on oxometal"V# precursors[
plexes in which dialkylaminothiolates are the mono! as a rhenium"V# precursor ð00Ł with a mixture of 1
dentate ligands\ since some of the {{2¦0|| complexes ðSNSŁ and 2 ðS"N#Ł\ the reactants 0\ 1 and 2 were used
are of interest with respect to brain imaging agents in various stoichiometric amounts "0]0]1\ 0]9[4]0 or
ð3\ 4Ł and play an important role in the search for 0]0]0#[ In all cases the expected {{2¦0|| mixed!ligand
neuroreceptorÐa.ne complexes[
complex 3 was formed and a second neutral rhe!
The involvement of two competing ligands in the nium"V# complex 4 was observed with an excess of 2
formation of the mixed!ligand complexes gives rise to over 0 and 1 or with the tridentate ligand as a minor
various species "Figure 0#[ Depending on the stoi! compound Fig[ 1[ 4 became the major product and
chiometric ratios of the ligands\ not only the desired could be isolated as a dark red\ stable\ crystalline solid
{{2¦0|| compound "a# but also complexes of only the in a 38 percent yield "Figure 1\ route b# when 1 was
monodentate ligands having a formal S3 coordination omitted in the reaction mixture[ A base such as sodium
"b# ð5Ł and dinuclear complexes "c# containing only acetate or triethyl amine in the reaction mixture seems
the tridentate ligand may be formed ð6\ 7Ł[
to be essential for the formation of 3 and 4[ No for!
In order to optimize the reaction conditions for the mation of 4 and less yields for 3 are observed after
preparation of such a complex 3 "Figure 1# by ligand re~uxing in methanol for one hour ð01Ł without
exchange reactions\ we studied the reaction of addition of the described bases[ 4 was also formed
ðReOCl2"PPh2#1Ł "0# with the tridentate ligand ðHSÐ in oxygen free solvents such as dichloromethane or
"CH1#1ÐN"CH1ÐCH1NEt1#Ð"CH1#1ÐSHŁ "1# ð8\ 09Ł and acetonitrile "Figure 2#[
dialkylaminothiolates such as 2 Fig[ 1[ When the tri!
Complexes 3 and 4 are readily soluble in organic
dentate ligand was used as the minor compound ver! solvents[ Elemental analysis shows that 3\ as expected\
sus one to one ratios of the dialkylaminothiolate and contains both the tridentate ligand 1 and the mono!
the metal precursor in reaction mixtures in order to dentate ligand 2\ while complex 4 contains ligand 2
avoid the formation of dinuclear bridged complex and one triphenylphosphane[
products\ two compounds were obtained[ One con!
sists of the expected {{2¦0||!product 3 while the other
is a hitherto unknown type of a cis!dioxorhenium"V#
complex\ 4[
0H NMR spectroscopy
0H NMR studies of 3 show signals with chemical
Here we describe the formation and structural
characterization of these new compounds[ Structure
investigations in solution using EXAFS were per!
formed in addition[
shifts identical to those found for the O!methylene!
bound protons of ligand 2 as well as the typical signal
pattern of the two ethyl groups bound to the ethylene
diamine fragment[ All this veri_es the presence of the
tris chelating ligand 1 in the complex[ In order to
identify the other protons of the coordinated ligand
RESULTS AND DISCUSSION
Starting
from
trans!monooxotrichlorobis! 1\ NOESY spectra of a similar compound ð8Ł bearing
"triphenylphosphine#rhenium"V# ðReOCl2"PPh2#1Ł "0# 1 were used for comparison[

A mixed ligand complex by ligand exchange reactions
2602
Fig[ 1[ Reaction scheme of the formation of the mono!oxo rhenium"V# complex 3 and the cis!dioxo rhenium"V# complex 4[
0HNMR investigations of 4 con_rm the formu! X!ray crystal structure
lation\ showing a signal pattern typical of phosphorus
bound to arylic protons and a de_ned multiplet signal
of four O!methylene bound protons in the expected
range[ Due to the bound nitrogen of the ring system
of 2 in case of 4\ the symmetry of the O!methylene
protons is disturbed and shows the splitting of the
signal pattern as expected[ The measured intensities
of the arylic:aliphatic signals yield a 0]0 ratio cor!
responding to 2:PPh2[
Crystals of 4 suitable for X!ray di}raction studies
were obtained by recrystallization from ether:n!
heptane[ The structure determination clearly reveals
the formation of a trigonal bipyramid[ As already
anticipated from IR data\ the O!donors are arranged
in a cis con_guration and form a plane with the S!
atom[ The phosphorus and nitrogen donors compose
the apices of the trigonal PÐReÐN bipyramid[ The
small distortion of the ideal 079> PÐReÐN angle is
caused by the S!donor in the trigonal plane[ In con!
trast to a trans!dioxo con_guration\ the OÐReÐO
angle is decreased to 024>[ Due to the OxÐReÐS angles
of about 001> and to P\N donors being perpendicular
to the trigonal plane\ a distorted trigonal bipyramid
is formed[ The parameter t\ introduced to classify _ve
coordinated complexes to squareÐpyramidal "tꢁ9# or
trigonalÐbipyramidal geometry "tꢁ0# ð05Ł\ was deter!
mined as 9[53[ Discrepancies concerning the ideal tri!
gonal bipyramid can be explained by the O2ÐReÐO3
angle of oxygen coordination in the equatorial plane[
In accordance with theory\ the bond length found for
IR spectroscopy
The IR spectrum of 4 did not show the intensive
signal at nꢁ834 cm−0 for Re1O as observed for 3[
Two intense bands shifted to shorter wave numbers
at nꢁ725 and 896 cm−0 were detected[ These values
are typical of the cis!O1Re1O group as recorded
for postulated ð02Ł or established ð03Ł cis!dioxorhen!
ium"V# coordinated complexes[
Unlike 3\ 4 needs the attack of an oxygen donor on
0 for its formation[ We assume that traces of water
are the source of the second oxygen in the cis!dioxo
arrangement of 4[ To prove this assumption\ ð07 OŁ
water was added to the reaction mixture[ As described
in literature ð04Ł the increased mass of the "07 O#!oxygen
in the molecule should e}ect a noticeable shift of the
obtained O1Re1O signals to shorter wave numbers[
The resulting 4 shows a modi_ed IR spectrum ðFig[
3"a#Ł\ where the oxo!rhenium stretches were shifted to
hꢁ687 cm−0 and hꢁ745 cm−0 and the exactly ident!
ical _ngerprint range clearly revealed the formation
of an ð07 OŁ!containing compound 4[ The found shifts
are in a comparable range to IR data of "07 O#ÐCO vs
"05 O#ÐCO ð04Ł studies[
Ä
the dioxo core increases to 0[62 A\ compared with
Ä
0[54 A for the mono!oxo core "Re1O\ 3# ð09Ł[ The
bond lengths of the other donors show no signi_cant
di}erences between structures ð09Ł such as 3 and 4
"Table 0#[
The occurrence of a dioxo core shows a remarkable
parallel to trans!dioxorhenium"V# compounds con!
taining ðP\ N\ ClŁ or ðP\ IŁ chelating systems ð03\ 06Ł[
We assume that this phenomenon results from the
tendency of the metal core to become neutral[ The cis!
dioxo con_guration of 4 is obviously in~uenced by
the steric e}ects of the ligand 2[ The C1 distance of

2603
M[ Friebe et al[
Fig[ 2[ X!ray crystallographic structure of 4[
both the nitrogen and sulphur donors a}ects the EXAFS investigations made it possible to trace the
arrangement out of the trigonal equatorial plane[ This structural relationships in the reaction mixture by con!
is caused by the intramolecular tension in 4 in oppo! sidering the neighbourhood closest to rhenium in the
sition to the coordination mode in the base plane of a solid "suspended# precursor state as well as in the
square pyramidal complex such as 3[ That fact soluted cis!dioxo compound state\ which are both pre!
excludes the trans!con_guration of the dioxo core[
sent in the reaction mixture[ A comparison of the
clari_ed crystal structure of 4 with its rhenium coor!
dination sphere in a non!crystalline state was of spe!
cial interest from a nuclear medical point of view[
XANES:EXAFS measurements
To better understand the changes in the atomic
environment of the central atom associated with the XANES data
formation of the cis!dioxo compound\ investigations
of the rhenium coordination sphere at the precursor
A strong white line as typical of measurements at
state and the _nal cis!dioxo complex state appeared the rhenium LIII absorption edge ð05Ł was observed for
to be helpful[ Therefore\ EXAFS measurements were both complexes under investigation[ The absorption
applied to deliver atomic radial distributions of the edge position of complex 0 was determined to be
ligand atoms around the rhenium central atom[ 09422 eV\ that of complex 4 was 09424 eV[ The di}er!

A mixed ligand complex by ligand exchange reactions
2604
Fig[ 3[ IR spectrum of 4 obtained by the reaction without addition of water "measured in CHCl2#[ "a# IR spectrum of 4
obtained by addition of ð07 OŁ water to the reaction mixture "measured in CHCl2#[
Ä
Table 0[ Selected bond distances "A# and angles "># of 4
Ä
Ä
Bond length "A#
Bond length "A#
Atoms
and angles ">#
Atoms
and angles ">#
ReÐO"2#
ReÐO"3#
ReÐS
ReÐN
ReÐP
O"2#ÐReÐO"3#
O"2#ÐReÐS
O"3#ÐReÐS
0[625"4#
0[624"4#
1[158"1#
1[179"5#
1[392"1#
024[8"2#
000[0"1#
002[9"1#
O"2#ÐReÐN
O"3#ÐReÐN
S"0#ÐReÐN
O"2#ÐReÐP
O"3#ÐReÐP
S"0#ÐReÐP
N"0#ÐReÐP
76[5"2#
82[9"1#
74[4"1#
75[4"1#
89[6"1#
86[32"7#
063[9"1#

2605
M[ Friebe et al[
Fig[ 4[ "a# EXAFS data of complex 0[ Dotted lines\ experimental data^ solid lines\ _t data[ "b# Fourier transform corresponding
to "a#[
Table 1[ EXAFS _t results for complex 0
A short!bound oxygen atom is detected at a dis!
tance of 0[69 A as is typical of a rhenium central atom
Ä
N
a
1
1
Ä
Ä
Shell
R "A#
s "A #
with a formal oxidation state of ¦4[ The second coor!
dination shell was _tted with a backscattering function
of the atomic number 05 as the mean number of phos!
phorus "atomic number 04# and chlorine "atomic num!
ber 06#\ since EXAFS functions for the latter are not
expected to be resolvable[ As the _t result for this
O
P:Cl
0[0"0#
4[1"3#
0[69"0#
1[30"0#
9[990"0#
9[994"0#
N is the number of coordinating atoms[ R] distance to
rhenium central atom[ s1] DebyeÐWeller factor[ Fit mode]
Marquardt algorithm using least squares method[ Calculated
Ä
shell\ _ve P:Cl atoms at a mean distance of 1[30 A were
Ä
1
Ä
resolution in distance] 9[05 A[ The theoretical resolution in
found[ The DebyeÐWeller factor of 9[994 A suggests a
distance is given by the formula DRꢁ1p:kmax ð08Ł DE9]
−7 eV[
a Distance to the rhenium central atom[
distribution of the backscattering atoms over a dis!
tance range within the coordination shell[ On the one
hand\ this may be due to the di}erence in distance
between the chlorine and the phosphorus atoms\ on
the other\ the relatively high coordination number of
_ve may also lead to increased DebyeÐWeller terms[
As described elsewhere ð19Ł\ the precursor complex 0
may occur in various forms of the general constitution
ReOCl2"PPh2#1[ These conformation isomers are
mainly characterized by di}erences in the PPh2 ligand
conformation and crystal packing patterns "mon!
oclinic and triclinic#\ which lead to changes in the
rheniumÐligand distances[ The rheniumÐoxygen bond
ence in the absorption edge position suggests di}erent
electron densities at both complex central atoms[
EXAFS data of 0
The Fourier transform of the complex 0 EXAFS
data consists of two coordination shells which are well
resolved[ Figure 4"a# and "b# show the EXAFS data\
their Fourier transforms and the corresponding _t
data of complex 0[
Ä
distances as elucidated by XRD analysis are 0[55 A
for one monoclinic "A# and one triclinic isomer "B#
Ä
and 0[62 A for the other triclinic monomer "C#[
Ä
EXAFS analysis of the precursor showed a rheniumÐ
The peak at 0[3 A in the Fourier transform "not
Ä
oxygen distance of 0[69 A\ which is regarded as a mean
corrected for scattering phase!shift# is thought to rep!
resent the short!bound oxygen atom\ the large peak
at 0[8 A is probably generated by the mixed chlor!
ine:phosphorus coordination shell[ Taking this model
as a default to _t the data\ the EXAFS _t data shown
in Table 1 were obtained[
value of various isomers\ including the triclinic isomer
C and one or both other isomers[ The EXAFS value
of the bond distance of the P:Cl coordination shell
also seems to represent a mean value of various
isomers\ since the mean value of this shell as shown
Ä

A mixed ligand complex by ligand exchange reactions
2606
5[ "a# EXAFS data of complex 4[ "b# Fourier transform corresponding to "a#[
Ä
Table 2[ EXAFS _t results for complex 4
by XRD analysis was 1[34\ 1[39 and 1[33 A for isomers
A\ B and C[ Hence\ an unambiguous assignment of
the analyzed isomers is not possible\ although the
existence of the triclinic isomer C can be assumed[
However\ the constitutional identity of the precursor
could be proven by EXAFS[
a
1
1
Ä
Ä
Shell
N
R "A#
s "A #
O
P:S
1[1"3#
0[7"2#
0[63"0#
1[22"0#
9[990"0#
9[995"0#
N is the number of coordinating atoms[ R] distance to
rhenium central atom[ s1] DebyeÐWeller factor[ Fit mode]
Marquardt algorithm using least squares method[ Calculated
resolution in distance] 9[05 A[ The theoretical resolution in
distance is given by the formula DRꢁ1p:kmax ð08Ł[DE9]
−8 eV[
EXAFS data of 4
Ä
Complex 4 exhibits a signi_cantly di}erent radial
distribution function around the rhenium central
atom[ Figure 5"a# and "b# show the EXAFS data and
their Fourier transform of complex 4[ Dotted lines
represent the experimental data\ solid lines the best
_t[
a Distance to the rhenium central atom[
A strong Fourier transform amplitude is detected
Ä
at 0[2 A "not corrected for scattering phase!shift# sug! increased\ probably caused by two distant back!
gesting a remarkably changed _rst coordination shell scatterers which were _tted within one coordination
with respect to the rhenium precursor[ A second peak shell[ These two atoms are thought to be a sulphur
Ä
Ä
occurs at 1[0 A\ obviously caused by the second coor! atom at a distance of around 1[16 A and a phosphorus
Ä
dination shell[ Taking the complex structure as eluci! backscatterer located at around 1[39 A[ The detected
dated by XRD analysis as a default to _t the data\ the bond length seems likely to represent the mean dis!
results presented in Table 2 were obtained[
tance between these two atoms[ The results obtained
A substantial increase in the coordination number are in good agreement with the values determined by
of the oxygen shell as well as an increase in its mean XRD analysis of the complex[ However\ there is a
bond distance to rhenium were observed[ This stron! discrepancy in view of the comparison of the crystal
gly suggests the existence of a dioxo rhenium core[ and the solution structure[ The nitrogen atom located
Ä
The bond distance is in excellent agreement with the at 1[17 A as determined in crystal is not detectable[
value determined by XRD analysis of the crystalline Attempts to include it in the EXAFS _t gave
complex[ Considering the second coordination shell\ unreasonable results and thus failed[ This problem
two sulphur backscatterers were used to _t the data is obviously caused by the strong dominance of the
and gave results of two backscattering atoms with a phosphorus:sulphur shell contribution in the complex
Ä
mean distance of 1[22 A[ It is noteworthy that the EXAFS[ The relatively weak backscattering con!
DebyeÐWeller factor of this coordination shell is tribution of the amine nitrogen atom at the expected

2607
M[ Friebe et al[
Ä
distance of 1[17 A is therefore not believed to be NMR investigations were carried out on a Varian
resolvable[ Similar phenomena were observed on Inova!399 device "solvent CDCl2#[ Mass spectrometry
other systems ð10\ 11Ł[ However\ it can be stated that was done using a Finnigan MAT 84 mass spec!
the unexpected complex as determined in XRD analy! trometer[ Column chromatography was done using
sis is also existent in solution and seems therefore to Silica gel 59 "9[93Ð9[952 mm# from Merck[
represent a relatively stable coordination[
Preparation of li`ands and the precursor
CONCLUSIONS
The
trans!mono!oxotrichlorobis"triphenylpho!
The described ligand exchange reaction procedure
resulted in 3 and the new complex species 4 with the
remarkable con_guration of the O!donor atoms and
an unexpected bidentate coordination of one mer!
captoethylene amine derivative[ H NMR\ FAB:CI
mass spectroscopy investigations and the elemental
sphine#rhenium"V# was prepared starting from per!
rhenate as described in the literature ð00Ł[
To prepare the ligands N\N!bis"1!mercaptoethyl#!
N?\N?!diethylethylenediamine 1 and 0\3!dioxa!7!aza!
spiro!N!1!mercaptoethylene!ð3\4Ł!decane 2\ a pub!
lished procedure was applied ð14Ł[
0
analysis suggest
a
0]0]0 ratio of 2\
a
tri!
phenylphosphane and a dioxo metal core[ The cis!
arrangement of the dioxo core could be proved by IR
investigations[ The completely trigonalÐbipyramidal
structure was elucidated by XRD measurements[ The
origin of the second short!bound oxygen proved to be
water present in the reaction mixture\ as shown by
07 O labelling studies[ Even at 0]0 to 0]2 ratios of the
reactants 0:2 no formation of further compounds
analogous to that shown in Fig[ 0 was observed[
Five!fold coordinated compounds of trigonalÐ
bipyramidal O!coordination ð12Ł\ S\ or bis!alkyl coor!
dination ð13Ł and cis!con_guration of the oxo groups
have previously been described mainly for rhe!
nium"VII# compounds[ For the oxidation state of ¦4\
however\ only the trans!con_guration has been pub!
lished\ with the exceptions of one P\P\I cis!dioxo com!
plex characterized ð03Ł by XRD\ as well as two
complexes containing bipyridyl compounds and a cis!
dioxo structure characterized by IR data ð02Ł[
XRD and EXAFS studies of 4 showed that the
coordination of the cis!dioxo compound is nearly
identical in the solid and in the soluted state[
The formation of the cis!dioxo complex is not spe!
ci_c to the applied amine thiol 2[ Products containing
other amino alkyl thiols which were obtained further
show almost the same UV!spectra and was charac!
terized by XRD in one special case "part of a further
publication#[
Preparation of compounds 3 and 4
The precursor 0 "055[9 mg\ 9[1 mmol# was sus!
pended in 19 ml of methanolic sodium acetate solution
"9[04 N# by gentle stirring[ The ligand 1 "06[8 mg\
9[0 mmol# and the co!ligand 2 "39[6 mg\ 9[1 mmol#
were dissolved in dichloromethane:methanol and
added as a mixture[ The resulting suspension was
heated at 69>C for 29 min and a change of colour from
yellowish green to greenish brown was observed[ The
reaction mixture was diluted with 09 ml of dichlo!
romethane\ washed twice with 09 ml of water and
the organic phase was extracted with 09 ml of 9[0 N
hydrochloric acid[ A dark red organic phase "4# and
a dark green aqueous phase "{{2¦0|| product 3# were
obtained[ The organic portion was dried over sodium
sulphate\ _ltered\ reduced in volume by evaporation
and puri_ed by chromatography over silica gel 59 with
trichloromethane as the liquid phase[ The eluate was
evaporated to dryness and the precipitate dissolved
in diethyl ether[ After adding a mixture of ether:n!
heptane "0]0#\ dark red\ analytically pure crystals were
obtained by slow evaporation of the solvents[ Yield]
56 mg "ca[ 38)\ referred to 0#^ m[p[ 061Ð063>C[ !
IR"KBr#] nꢁ725^ 896 cm−0 "O1Re1O#[ Mass spec!
trum] "FAB pos[# m:z 570"21#:572"67# ðMŁ¦^
571"51#:573"099# ðM¦HŁ¦^ 0H NMR"CDCl2#] d 2[832
ðm\ 3H\ OÐCH1ÐCH1ÐO "2#Ł\ d 2[255 ðm\ 1H\ NÐCH1Ð
CH1ÐS "2#Ł\ d 1[699 ðm\ 1H\ SÐCH1ÐCH1 "2#Ł\ d 1[559^
1[234 ð1m\ 3H\ NÐCH1ÐCH1 "2#Ł\ d 0[585^ 0[417 ð1m\
3H\ CÐCH1ÐCH1 "2#Ł[
Regarding the {{2¦0|| approach it has to be
remarked the reactants should be used strictly in a
0]0]0 ratio in cases of such potentially bidentate
ligands[ A compensation of the higher reactivity of
the tris chelating unit by the use of an excess of the
{{monodentate|| co!ligand 2 is impossible[
A quantity of dichloromethane was added to the
dark green aqueous phase and the pH was increased
to 09 by adding a small volume of sodium hydroxide
in order to re!extract compound 3[ The organic por!
tion was dried over sodium sulphate\ _ltered and
reduced in volume by evaporation[ Compound 3 was
puri_ed by chromatography as described above and
EXPERIMENTAL SECTION
Materials and instrumentation
eluted by using
a
mixture of dichloro!
Elemental analyses were performed on a LECO methane:methanol "08]0#[ The solvent mixture was
CHNS!821 elemental analyser[ Infrared spectra "KBr removed by allowing to stand overnight and crude
pellets\ in CHCl2# were measured on a Specord M79 green crystals were obtained[ Yield] 39 mg "ca[ 51)\
or on a Perkin Elmer FT!IR Spectrum 1999[ Proton referred to 1#^ m[p[ 023Ð025>C[ IR"KBr#] nꢁ834 cm−0

A mixed ligand complex by ligand exchange reactions
2608
"Re1O#[ Mass spectrum] "CI neg[# m:z X0[0 of the HASYLAB synchrotron\ Hamburg\ Ger!
526"47#:528"099# ðMŁ¦[ 0H NMR "CDCl2#] d 2[842 ðs\ many[ To monochromatize the synchrotron beam\ a
3H\ OÐCH1ÐCH1ÐO "2#Ł\ d 1[610 ðm\ 3H\ NÐCH1ÐCH1 monochromator system consisting of a Si"100# dou!
"2#Ł\ d 0[794 ðt\ 3H\ NÐCH1ÐCH1ÐC "2#Ł\ d 2[761 ðt\ ble!crystal monochromator was used[ The DORIS III
1H\ NÐCH1ÐCH1ÐNEt1 "1#Ł\ d 2[515^ 2[473^ 2[181^ storage ring was operated at 2 GeV at ring currents
1[860 ðm\ 7H\ NÐCH1ÐCH1ÐS "1#Ł\ d 1[759 ðt\ 1H\ NÐ between 39 and 69 mA during measurements[ Higher
CH1ÐCH1ÐNEt1 "1#Ł\ d 1[591 ðm\ 1H\ SÐCH1ÐCH1ÐN harmonics were rejected by detuning the mono!
"1#Ł\ d 1[455 ðq\ 3H\ NÐCH1ÐCH2 "1#Ł\ d 0[950 ðt\ 5H\ chromator crystals to 49) of the incident beam inten!
NÐCH1ÐCH2 "1#Ł[
sity[ A rhenium"V# complex served as a reference for
energy calibration of the monochromator[ Three
scans were used per sample on average[ A check for
anomalies was carried out after each scan[ Data were
energy!calibrated using the _rst derivative method\
where the _rst in~ected point in the reference deriva!
tive was set to 09424 eV[ Sample absorption edge pos!
itions were determined by derivatizing the sample
spectra and detecting the _rst in~ected points[ Data
processing and analysis were performed using the pro!
gram package EXAFSPAK ð15Ł[ The experimental
data were analyzed by being _tted with theoretical
EXAFS functions generated by the FEFF5[90a pro!
gram ð16Ł[ Since phosphorus\ sulphur and chlorine
produce very similar backscattering functions\ mixed!
atom coordination shells consisting of these atoms
were _tted with EXAFS functions for sulphur back!
scatterers[ To _t the data\ coordination numbers were
at _rst kept constant[ When constant values for DE9
and distances were obtained\ coordination numbers
were allowed to ~oat[
Preparation of the ð07 OŁ!bearin` complex 4
The precursor 0 "055[9 mg\ 9[19 mmol# was sus!
pended in a mixture of 0 ml of ð07 OŁ water and 4 ml
dried methanol which contained water!free sodium
acetate "9[04 N#[ After addition of
2 "36[7 mg\
9[13 mmol# dissolved in 9[4 ml of dried methanol the
reaction mixture was stirred and re~uxed for 29 min[
The dark reddish solution obtained was reduced in
volume by evaporation to give a _nal volume of
approximately 1 ml[ The solution was applied to a
silica gel column and puri_ed by eluting with chloro!
form[ The dark reddish chloroformic solution
obtained was used for IR measurements[
X!ray crystal structure analysis of 4
The structure was determined using a single crystal\
obtained by slow evaporation of an ether:n!heptane
solution of 4[ C16H20N0O3P0S0Re0 "Mꢁ571[68#[ The
intensity data for compound 4 were collected on a
ENRAF!NONIUS CAD3 di}ractometer[ The re~ec!
tions were performed by the vÐ1u scan method\ using
Acknowled`ements*We are grateful to S[ Machill of the
Technische Universitat Dresden for measuring the FAB:CI
Ã
mass spectra[
graphite
monochromated
CuKa
radiation
Ä
"lꢁ0[4307 A# at Tꢁ185"1# K[ Triclinic space group
P!0 "No[ 1#\ aꢁ8[212"2# A\ bꢁ04[327"2# A\
cꢁ19[560"2# A\
gꢁ094[28"2#>\
Ä
Ä
REFERENCES
Ä
aꢁ092[07"2#>\
bꢁ099[28"2#>\
2
Ä
Vꢁ1588[5"00# A \
Zꢁ3\
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Dcꢁ0[566 g cm−2\ mꢁ09[244 mm−0[ The number of
totally measured re~ections was 00966\ of which 8836
were considered to be signi_cant and were used for
the structure determination[ The re_nement pro!
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where the minimized function was v"=F9=−=Fc=#1[
Re_nement converged at Rꢁ9[9403 and Rwꢁ9[0410[
Crystallographic data "excluding structure factors#
for the structure reported in this paper have been
deposited at the Cambridge Crystallographic Data
Center[ Copies of the data can be obtained free of
charge on application to The Director\ CCDC\ 01
Union Road\ Cambridge CB1 0EZ\ U[K[ "fax] ¦33!
0112!225!922^ e!mail] techedÝchemcrys[cam[ac[uk#
"CCDC!No[ 099360#[
in
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