Simultaneous cation/anion coordination by bifunctional 1,2-diimine/1,2-diamine type ligands: Synthesis, structures, and properties of tight ion pair complexes of ruthenium and iron

Article abstract of DOI:10.1002/1099-0682(200211)2002:11<2800::AID-EJIC2800>3.0.CO;2-E

The reaction between [η⁶-p-cymene)RuCl₂]₂ and tetra-p-tolyloxalic amidine (oxam1) results in a coupled cation/anion coordination forming the ion-paired complex [(η⁶-p-cymene)RuCl(oxam1)Cl] (1a). According to an X-ray single crystal diffraction analysis the Ru moiety is coordinated at the 1,2-diimine part yielding a five-membered chelate ring. Furthermore, the 1,2-diamine group on the opposite side binds to a chloride anion via two N-H groups. Exchange of the chloride anion by trifluoractetate yields [(η⁶-p-cymene)RuCl(oxam1)CF₃CO₂] (1c) in which the C=O group is bonded to the diamine part. Similarly, bis(mesityl)bis(pyridylmethyl)oxalic amidine (oxam2) reacts with FeX₂ to yield the ion-paired complexes 3a (X: Cl), and 3b (X: Br). X-ray diffraction studies of both compounds reveal that the oxalic amidine ligand acts as a four-dentate chelating ligand. One halide is fixed in the same way as in 1a. The complex 1a reacts with Pd(acac)₂ (acac: acetylacetonate) to give the tetranuclear heterobimetallic complex [(η⁶-p-cymene)RuCl-(oxam1)PdCl]₂ (2). The related complexes [(tbbpy)₂Ru-(bbimH₂)(OOC-CF₃)] (PF₆) (4), [(tbbpy)₂Ru(bbimH₂){OOC- (CF₂)₇CF₃})][OOC(CF₂) TCF₃] (5), [{(tbbpy)₂Ru(bbimH₂)}₂- (OOC-C₆F₄-COO)](PF₆)₂ (6), and [{(tbbpy)₂Ru-(bbimH₂)}₂ (OOC-C₆F₄-COO)] (7), (bbimH₂: bibenzimidazole; tbbpy: 4,4′-di-tert-butyl-2,2′-bipyridine) also form ion-paired compounds. According to the X-ray diffraction analyses of 4-6 both oxygen atoms of the carboxylate ions are coordinated to the two N-H functions via strong N-H...O bonds. Although 5 contains a dication, the compound is soluble in solvents of low polarity, even in supercritical carbon dioxide. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.

Full text of DOI:10.1002/1099-0682(200211)2002:11<2800::AID-EJIC2800>3.0.CO;2-E

FULL PAPER
Simultaneous Cation/Anion Coordination by Bifunctional 1,2-Diimine/1,2-
Diamine Type Ligands: Synthesis, Structures, and Properties of Tight Ion Pair
Complexes of Ruthenium and Iron
Sven Rau,[a] Lars Böttcher,[a] Sebastian Schebesta,[a] Michael Stollenz,[a] Helmar Görls,[a]
and Dirk Walther*[a]
Keywords: Iron / Hydrogen bonds / N ligands / Ruthenium
The reaction between [(η6-p-cymene)RuCl2]2 and tetra-p-to-
lyloxalic amidine (oxam1) results in a coupled cation/anion
reacts with Pd(acac)2 (acac: acetylacetonate) to give the
tetranuclear heterobimetallic complex [(η6-p-cymene)RuCl-
coordination forming the ion-paired complex [(η6-p-cy- (oxam1)PdCl]2 (2). The related complexes [(tbbpy)2Ru-
mene)RuCl(oxam1)Cl] (1a). According to an X-ray single
crystal diffraction analysis the Ru moiety is coordinated at
the 1,2-diimine part yielding a five-membered chelate ring.
Furthermore, the 1,2-diamine group on the opposite side
binds to a chloride anion via two N−H groups. Exchange of
(bbimH2)(OOC−CF3)](PF6) (4), [(tbbpy)2Ru(bbimH2){OOC-
(CF2)7CF3})][OOC(CF2)7CF3] (5), [{(tbbpy)2Ru(bbimH2)}2-
(OOC−C6F4−COO)](PF6)2
(6),
and
[{(tbbpy)2Ru-
(bbimH2)}2(OOC−C6F4−COO)] (7), (bbimH2: bibenzimida-
zole; tbbpy: 4,4Ј-di-tert-butyl-2,2Ј-bipyridine) also form ion-
the chloride anion by trifluoractetate yields [(η6-p-cy- paired compounds. According to the X-ray diffraction ana-
mene)RuCl(oxam1)CF3CO2] (1c) in which the C=O group is
bonded to the diamine part. Similarly, bis(mesityl)bis(pyrid-
lyses of 4−6 both oxygen atoms of the carboxylate ions are
coordinated to the two N−H functions via strong N−H···O
ylmethyl)oxalic amidine (oxam2) reacts with FeX2 to yield bonds. Although 5 contains a dication, the compound is sol-
the ion-paired complexes 3a (X: Cl), and 3b (X: Br). X-ray uble in solvents of low polarity, even in supercritical carbon
diffraction studies of both compounds reveal that the oxalic
amidine ligand acts as a four-dentate chelating ligand. One
halide is fixed in the same way as in 1a. The complex 1a
dioxide.
( Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany,
2002)
Introduction
Structure B, the tautomer of A can be stabilized by
formation of a 1,2-diimine metal compound provided a
suitable metal complex fragment is used. Additionally, an-
ion bonding via hydrogen bonds on the opposite 1,2-di-
amine side of the oxalic amidine system may stabilize the
mononuclear complex preventing undesired coordination
polymerization.
Oxalic amidines containing the structural element A are
not only variable building blocks for bi- and oligonuclear
complexes[1Ϫ8] but can also be considered as bifunctional
ligands which should be capable of coupled cation/anion
coordination forming tight contact ion-paired complexes
according to Scheme 1.
The general principle behind this process is strongly re-
miniscent of anion recognition events in supramolecular
chemistry between cationic diamine-based hosts and an-
ionic guests.[9] The stability of the resulting aggregates is
commonly influenced by steric and electronic tuning of the
host molecule with regard to the guest. The application of
these construction principles in metallorganic and coor-
dination chemistry is still relatively underdeveloped even so
multinuclear supramolecular aggregates are promising can-
didates for multistep catalytic processes or biomimetic ana-
logues, such as light harvesting complexes.
Scheme 1. Formation of ion-paired complexes by coupled cation/
anion coordination
Simultaneous cation/anion coordination could therefore
result in the generation of ‘‘supramolecularly’’ protected
metalloligands, useful as starting products for the construc-
tion of heterobi- or oligometallic complexes, but also for
the formation of ion-paired metal complexes with untypical
high solubilities in solvents of low polarity. In addition, in-
[a]
Institut für Anorganische und Analytische Chemie,
Universität Jena
August-Bebel-Straße 2, 07743 Jena, Germany
Fax (internat) ϩ 49-(0)3641/948102
E-mail: cdw@rz.uni-jena.de
2800  2002 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim 1434Ϫ1948/02/1111Ϫ2800 $ 20.00ϩ.50/0 Eur. J. Inorg. Chem. 2002, 2800Ϫ2809

Tight Ion Pair Complexes of Ruthenium and Iron
FULL PAPER
teraction of dicarboxylates as dianions with appropriately
designed 1,2-diamine containing complexes should result in
the formation of hydrogen-bonded stable dimers. Further-
more, this type of reaction may be used to force ligands
bearing additional donor groups in R1 into untypical coor-
dination modes. Additionally, the generation of 1,2-diimine
metal species containing cationic electrophilic parts may be
of special interest because of their well-known catalytic po-
tential.[10,11]
We describe here the first examples for simultaneous cat-
ion/anion bonding using oxalic amidines as ligands and in-
vestigate the structures and properties of the new com-
pounds. Furthermore, we report on ion-paired complexes
consisting
of
the
photoactive
fragment
(tbbpy)2Ru(bbimH2)2ϩ and carboxylates that are hydrogen
bonded to the related bibenzimidazole ligand. Although in
these complexes a dication is part of the tight ion-paired
compound, these compounds show surprisingly high solu-
bilities in nonpolar solvents if long chained perfluoro-substi-
tuted carboxylates are coordinated to the NϪH groups.
˚
Figure 1. Molecular structure of complex 1a, selected distances [A]
and bond angles [deg]: RuϪCl1 2.398(1), RuϪX1A 1.692(4),
RuϪN1 2.088(3), RuϪN2 2.079(3), C1ϪN1 1.301(4), C1ϪN3
1.436(4), C1ϪC2 1.497(4), C2ϪN2 1.298(4), C2ϪN4 1.350(5),
Cl2ϪN3 3.077(2), Cl2ϪN4 3.088(2); X1AϪRuϪCl1 128.60(7),
X1AϪRuϪN1 83.9(2), X1AϪRuϪN2 83.5(2), Cl1ϪRuϪN1
83.93(9),
N1ϪC1ϪN3 127.2(3), N2ϪC2ϪN4 127.4(3), C1ϪC2ϪN2
114.1(3), C1ϪC2ϪN4 118.2(3), C2ϪC1ϪN1 114.1(3),
C2ϪC1ϪN3 118.6(3)
Cl1ϪRuϪN2
83.54(8),
N1ϪRuϪN2
75.9(1),
Results and Discussion
Reaction between [(η6-p-cymene)RuCl2]2 and tetra-p-to-
lyloxalic amidine (oxam1) in refluxing toluene resulted in
the formation of [(η6-p-cymene)RuCl(oxam1)Cl], 1a, which torted trigonal pyramidal geometry considering the aro-
was isolated as an orange-red crystalline compound at matic ring as a unique coordination site, represented by the
room temperature. Elemental analysis and a mass spectrum middle of the benzene unit, occupying one position of the
confirmed its composition. In the ESI-mass spectrum the polygon. The second chloride is bonded to the two NϪH
1
complex ion [1a Ϫ Cl]ϩ (m/z ϭ716) was detected. The H groups of the 1,2 diamine part of the oxalic amidine via
NMR spectrum of 1a, recorded in [D8]THF at room tem- two hydrogen bonds. Bond lengths and angles are listed in
perature supports the assumption of a Cs symmetrical com- the figure caption and lie within typical ranges (see Figure 1
plex. It showed one doublet belonging to the methyl pro- caption). The C1ϪN1 and C2ϪN2 bond lengths of
˚
tons of the isopropyl group at δ ϭ 1.14 and 1.17 ppm and 1.301(4), and 1.298(4) A clearly indicate that the ligand co-
a singlet for the methyl group of coordinated cymene at ordinates with the 1,2-diimine part. Typically, due to the
δ ϭ 2.27 ppm. Two singlets for the methyl groups of the partial delocalization of the double bonds of the coordina-
˚
coordinated oxam1 were detected at δ ϭ 2.09 and 2.18 ppm. ted 1,2 diimine, the C1ϪC2 bond length 1.497(4) A is
The relative intensities of these resonances are, as expected, shorter than that of a CϪC single bond. The N3ϪCl2 and
˚
(1:1):(1:2):2. The multiplet corresponding to the CH proton N4ϪCl2 distances of 3.077(2) and 3.088(2) A, respectively,
of the isopropyl group was detected at δ ϭ 2.50 ppm. The are in the accepted range for these distances. Furthermore,
aromatic protons of the p-cymene ligand (δ ϭ 4.59 ppm), the angles for the N3ϪH···Cl group, and the N4ϪH···Cl
and the protons of the aromatic substituents (δ ϭ 6.66 and group (167 and 170°, respectively) show very little deviation
7.60 ppm) were detected with the expected intensities. Fur- from linearity. These findings clearly indicate a strong
1
thermore, the H NMR spectrum shows one sharp singlet bonding between the NϪH functions of the 1,2-diamine
for both NH groups at δ ϭ 12.83 ppm, which is in agree- system and the chloride counterion. In the related com-
ment with a strong chloride binding to the NϪH functions pound tris(N,NЈ-diphenyloxalic amidineϪN,NЈ)cobalt(II)
according to Figure 1. The 13C NMR spectrum for 1a in dichloride, the peripheral primary amine functions form
[D8]THF also showed the expected simple pattern corres- tight hydrogen bonds to one chloride anion resulting in a
ponding to a symmetrical complex.
polymeric three-dimensional network.[12]
The molecular structure of compound 1a has been con-
The complex 1a has been proven to be a suitable ‘‘pro-
firmed by X-ray crystallography (Figure 1). The compound tected’’ ligand for the construction of oligonuclear com-
consists of a cationic portion in which the metal center is plexes containing different metals. For example, reaction
surrounded by the p-cymene, the diimine part of the oxalic with Pd(acac)2 resulted in the formation of the tetranuclear
amidine ligand and one chloride to form a typical ‘‘piano complex 2 containing palladium atoms in the inner part
stool’’ complex in which the arene acts as the ‘‘bench’’ and and two ruthenium centers on the peripheries (Scheme 2).
the other ligands form ‘‘the legs’’ of the stool. The ruthe- Elemental analysis and a mass spectrum confirmed its com-
nium coordination environment is best described as a dis- position. In the ESI-mass spectrum the complex cation [M
Eur. J. Inorg. Chem. 2002, 2800Ϫ2809
2801

S. Rau, L. Böttcher, S. Schebesta, M. Stollenz, H. Görls, D. Walther
FULL PAPER
Ϫ Cl]ϩ m/z ϭ 1679 was detected and the obtained isotope
pattern agrees well with the calculated molecular formula
1
C80H84Cl3N8Pd2Ru2. Furthermore, the H NMR and the
13C NMR spectra of 2 ([D8]THF at room temperature)
show the expected signals for a symmetrical complex and
are similar to those of 1a, except for the absence of the
signals of the NϪH protons. Red single crystals of com-
pound 2 obtained from toluene were subjected to an X-ray
diffraction analysis. Figure 2 displays the molecular struc-
ture of 2.
˚
Figure 2. Molecular structure of complex 2, selected distances [A]
and bond angles [deg]: RuϪCl2 2.431(1), RuϪX1A 1.681(4),
RuϪN4 2.104(3), RuϪN3 2.082(3), PdϪCl1 2.333(1), PdϪCl1A
2.341(1), PdϪN1 1.989(4), PdϪN2 2.011(3), C1ϪN1 1.342(5),
C1ϪN3 1.312(5), C1ϪC2 1.495(5), C2ϪN2 1.332(5), C2ϪN4
1.318(5); X1AϪRuϪCl2 127.8(1), X1AϪRuϪN3 86.5(2),
X1AϪRuϪN4 83.8(2), Cl2ϪRuϪN3 86.8(1), Cl2ϪRuϪN4
83.8(1),
N3ϪRuϪN4
76.7(1),
Cl1ϪPdϪCl1A
82.99(4),
Cl1ϪPdϪN1 179.4(1), Cl1ϪPdϪN2 97.7(1), N1ϪPdϪN2 81.7(1),
N1ϪPdϪCl1A 97.6(1), N2ϪPdϪCl1A 179.3(1), N1ϪC1ϪN3
129.8(4),
N2ϪC2ϪN4
130.9(4),
C1ϪC2ϪN2
114.9(3),
C1ϪC2ϪN4 114.2(3), C2ϪC1ϪN1 114.7(3), C2ϪC1ϪN3 115.5(3)
(1b not depicted) are identical to 1a within experimental
-
errors. One fluoro substituent of the BF4 anion does form
a hydrogen bond to both NH function [N3ϪF4 2.825(4)
˚
and N4ϪF4 3.034(4) A]. The surprisingly short N3ϪF4
distance might be due to packing effects. Similar NϪH···F
hydrogen bond patterns have been observed in related cop-
per azophenine complexes.[13]
The trifluoroacetate anion in 1c does form a hydrogen
bond with both NH functions of the coordinated oxalic
amidine (Figure 3). However, in contrast to the usual bond-
Scheme 2. Formation of the tetranuclear heterobimetallic com-
plex 2
The Ru(oxam1)PdCl2Pd(oxam1)Ru core of 2 is essen- ing mode of carboxylate anions in previously reported re-
tially planar and the peripheral ligands cymene and chlor- lated metal complexes containing a diimine/diamine[14–16] in
ide are trans with respect towards each other. The coordina- 1c only the oxygen of the CϭO group [C41ϪO2 ϭ 1.176(7)
˚
tion geometry around the ruthenium centers is the same as A] is involved in the hydrogen bond network. The relatively
˚
in 1a.
Exchange of the hydrogen bonded chloride in 1a by BF4
short NϪH···O distances of 2.771(3), and 2.761(3) A, re-
spectively suggest a very strong interaction.
Ϫ
or trifluoroacetate anions in THF resulted in the formation
The formation of the complexes 3a and 3b between bis-
of the complexes [(η6-p-cymene)RuCl(oxam1)BF4] (1b), and (mesityl)bis(pyridylmethyl)oxalic amidine (oxam2) and
1
[(η6-p-cymene)RuCl(oxam1)OOCCF3] (1c). The H NMR FeX2 (X: Cl, Br) clearly demonstrates that coupled cation/
spectra of both compounds in [D8]THF showed nearly anion coordination can also be used for realizing untypical
identical signals for all of the CH groups; however the sig- coordination modes (Scheme 3). Whereas in transition
nals for the NH protons were very different. In 1b this sig- metal complexes containing additional coordinating an-
nal appeared at δ ϭ 9.05 ppm as a sharp singlet. The mag- ionic chelate ligands (such as acetylacetonate), oxam2 typic-
nitude of this upfield shift (δ ϭ 3.8 ppm) is indicative of a ally acts as a three-dentate bridging ligand in dinuclear
weaker hydrogen bond interaction compared with 1a. In complexes[18Ϫ20] whereas it forms mononuclear tetradentate
contrast, the trifluoroacetate complex 1c showed very broad complexes with iron halides.
NH signals between δ ϭ 11 and δ ϭ 12 ppm, characteristic
The solid-state structure of 3a determined by X-ray dif-
of a fast proton exchange or rotational effect. At lower tem- fraction analysis shows the oxalic amidine ligand to be co-
perature the signal became sharper at around δ ϭ 11.6 ppm. ordinated as tetradentate ligand in its prototropic form
This low-field shift is indicative of a stronger hydrogen (Figure 4). The 1,2-diimine now residing on the picolyl
bond than that in 1b.
based nitrogens is coordinated together with the pyridine
The solid-state structure of 1b and 1c could be deter- donor sites to the five-coordinated FeII with the chloride
mined by X-ray analyses. Both ruthenium cymene moieties ligand in the apical position resulting in a square-planar
2802
Eur. J. Inorg. Chem. 2002, 2800Ϫ2809

Tight Ion Pair Complexes of Ruthenium and Iron
FULL PAPER
˚
Figure 3. Molecular structure of complex 1c, selected distances [A]
and bond angles [deg]: RuϪCl 2.406(1), RuϪX1A 1.687(4),
RuϪN1 2.079(3), RuϪN2 2.084(3), C1ϪN1 1.304(5), C1ϪN3
1.344(5), C1ϪC2 1.513(6), C2ϪN2 1.308(5), C2ϪN4 1.347(5),
O2ϪN3 2.761(3), O2ϪN4 2.771(3); X1AϪRuϪCl 128.3(1),
X1AϪRuϪN1 85.4(2), X1AϪRuϪN2 84.4(2), ClϪRuϪN1
85.2(1), ClϪRuϪN2 84.4(1), N1ϪRuϪN2 75.8(1), N1ϪC1ϪN3
˚
Figure 4. Molecular structure of complex 3a, selected distances [A]
and bond angles [deg]: FeϪCl1 2.663(9), FeϪN1 2.091(2), FeϪN2
2.148(2), FeϪN3 2.089(2), FeϪN4 2.181(2), C1ϪN3 1.296(3),
C1ϪN6 1.336(3), C1ϪC2 1.535(4), C2ϪN1 1.284(3), C2ϪN5
1.350(3), Cl2ϪN5 3.051(1), Cl2ϪN6 3.152(1); Cl1ϪFeϪNl
109.27(7), Cl1ϪFeϪN2 104.27(7), Cl1ϪFeϪN3 114.36(7),
Cl1ϪFeϪN4 107.66(7), NlϪFeϪN2 76.98(9), N1ϪFeϪN3
75.64(9), N1ϪFeϪN4 140.04(9), N2ϪFeϪN3 138.13(9),
N2ϪFeϪN4 108.03(9), N3ϪFeϪN4 75.70(9), N6ϪC1ϪN3
129.0(4),
N2ϪC2ϪN4
127.5(4),
C1ϪC2ϪN2
113.5(4),
C1ϪC2ϪN4 118.9(4), C2ϪC1ϪN1 113.6(3), C2ϪC1ϪN3 117.4(4)
128.8(3),
N1ϪC2ϪN5
128.5(3),
C1ϪC2ϪN1
113.6(2),
C1ϪC2ϪN5 117.9(2), C2ϪC1ϪN3 112.7(2), C2ϪC1ϪN6 118.5(2)
The cores of bibenzimidazole (bbimH2) and biimidazole
(bimH2) are structurally related to the oxalic amidine ligand
family. However, electronic differences exist which manifest
themselves in different pKa values of the coordinated li-
gands.[3,17] Since ruthenium polypyridyl complexes of these
ligands are photoactive it was our aim to use the coupled
cation/anion coordination for the formation of tight ion-
paired, photoactive complexes. The appropriate choice of
anions should lead to stable assemblies of potentially higher
nuclearity and in addition a tuning of their solubility in
nonpolar solvents could be envisaged.
Scheme 3. Structure of the free ligand bis(mesityl)bis(pyridylmethyl)-
oxalic amidine, and coordination mode in the iron complexes 3a
and 3b
It is known that some biimidazole (bimH2) can form
pyramidal coordination environment. Similarly to complex complexes in which one anion is linked to the imidazole
1a, one halide is coordinated to the two NϪH groups on based NH groups via hydrogen bonds;[21Ϫ28] however, in
the opposite side of the oxalic amidine frame yielding a most cases polymeric networks resulted.[21,22Ϫ24] In con-
˚
zwitterionic complex [Cl2ϪN5 ϭ 3.051(1) A, Cl2ϪN6 ϭ trast, well-defined mononuclear ion-paired bibenzimidazole
3.152(1) A]. Other relevant bond lengths and angles fall in complexes are rare. AgI and CuI complexes containing asso-
˚
the range of typical values. The internal bond length and ciated chloride or acetate anions have been characterized
angles of the central oxalic amidine are similar to those in by de Souza Lemos.[25,26] Iron(II) complexes with bbimH2
1a. In contrast to 1a, the plane arranged by the four nitro- exhibit complex hydrogen bonding patterns where cationic
gen donor atoms of the central oxalic amidine frame of 3a complexes are linked via hydrogen bonds to their respective
is slightly distorted. More significant are the differences be- anions.[15] Recently, Beauchamp et al. have shown that some
tween the bond angles Cl1ϪFeϪN2 [104.27(7)°] and bimH2 ReIII complexes form hydrogen bonds with halides
Cl1ϪFeϪN4 [107.66(7)°] respectively to Cl1ϪFeϪN1 or benzoate anions resulting in ion pairs that are stable in
[109.27(7)°] and Cl1ϪFeϪN3 [114.36(7)°]. These differ- organic solvents.[16,27,28]
ences result in a distorted square pyramidal coordination
In an initial work we have shown that NϪH groups of
arrangement in 3a. In this arrangement the iron center is bbimH2 Ru complexes bind water molecules resulting in hy-
‘‘out of plane’’ coordinated similar to well-known hem iron drogen bonded networks. The variation of the noncoordin-
systems. According to X-ray structural analysis, 3b has the ating anion determined the supramolecular aggregation in
same ion-paired structure as 3a.
these compounds.[29]
Eur. J. Inorg. Chem. 2002, 2800Ϫ2809
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S. Rau, L. Böttcher, S. Schebesta, M. Stollenz, H. Görls, D. Walther
FULL PAPER
Based on these observations we choose to employ carb-
oxylate anions in an attempt to obtain stable aggregates.
The trifluoroacetate complex [(tbbpy)2Ru(bbimH2)-
(OOCϪCF3)](PF6) (4), could easily be prepared by depro-
tonation of [(tbbpy)2Ru(bbimH2)](PF6)2 followed by reac-
tion of the deprotonated complex with the trifluoroacetic
acid.
[(tbbpy)2Ru(bbimH2){OOC(CF2)7CF3})][OOC-
(CF2)7CF3] (5) was prepared by deprotonation of [(tbbpy)2-
Ru(bbimH2)](Cl)2 followed by reaction of the fully depro-
tonated complex with the corresponding acid. The 1H
NMR spectra of both 4 and 5 show a new signal at δ ϭ
16.4 ppm in deuterated acetone in addition to the other sig-
nals for the complex cation (see Exp. Sect.). Its broadness
and extreme low-field shift suggests that it corresponds to
the NϪH protons. Since a signal for these protons in other
ruthenium polypyridyl complexes with bbimH2 as ligand
has never been observed,[29] we assume that strong ion par-
ing may explain this effect. The ESI-mass spectroscopical
investigation confirmed the nature of the complex cation.
The solid-state structure of 4 elucidated by an X-ray dif-
fraction study showed the expected complex cation where
the bibenzimidazole ligand coordinates via the 1,2-diimine
part to the RuII atom that exhibits distorted-octahedral
geometry. The peripheral NH functions form hydrogen
bonds to the carboxylate anion resulting in an ion-paired
structure (Figure 5). The distances between hydrogen atoms
of the NϪH functions and the oxygens of the carboxylate
˚
Figure 5. Molecular structure of complex 4, selected distances [A]
and bond angles [deg]: RuϪN1 2.086(3), RuϪN2 2.109(3), RuϪN5
2.038(2), RuϪN6 2.037(3), RuϪN7 2.042(3), RuϪN8 2.074(3),
C1ϪN11.332(5), C1ϪN3 1.336(6), C1ϪC8 1.433(6), C8ϪN2
1.328(6), C8ϪN4 1.359(6), N4ϪO1 2.659(3), N3ϪO2 2.703(3),
O1ϪC51 1.257(6), O2ϪC51 1.223(6), N1ϪRuϪN2 77.5(1);
N1ϪRuϪN5 88.3(1), N1ϪRuϪN6 93.6(1), N1ϪRuϪN7 173.4(1),
N1ϪRuϪN8 97.2(1), N1ϪC1ϪN3 114.0(4), C1ϪC8ϪN2 117.3(4),
C1ϪC8ϪN4 129.1(4), C8ϪC1ϪN1 115.9(4), C8ϪC1ϪN3
130.0(4), O1ϪC51ϪO2 131.2(5)
˚
[N3ϪO1 ϭ 2.703(3), N4ϪO1 ϭ 2.659(3) A] are in the range
of strong hydrogen bonds.[29] In contrast to the hydrogen
bond association in 1c, both NH function interact with both
carboxylate oxygens in 4. The complementary topology of
the secondary amines of coordinated bibenzimidazole and
the carboxylate anions allows a more efficient interaction
between both parts leading to two strong NϪH···O bonds
(see also Figure 3).
In order to understand why the two strongly related com-
plexes, 1c and 4, form different hydrogen bonding networks
with trifluoroacetate the central cores of 1b and 4 were su-
perimposed on each other (Figure 6). It is clearly evident
from Figure 6 that the steric demand of the aryl substitu-
ents at the nitrogens in 1c determines the C1ϪN3ϪH angle
in such a way that a favorable hydrogen bond interaction is
only possible with one hydrogen bond acceptor. In contrast,
the bibenzimidazole ligand in 4 is bent around the ruth-
enium center[29] that results in the orientation of the two
NH functions towards two hydrogen bond acceptors.
Figure 6. Least square fit of parts of complex 1c and 4, torsion
angles N3ϪC1ϪC2ϪN4: for 1c Ϫ1.2° and for 4 Ϫ2.4°; distance
˚
˚
N3ϪN4: for 1c 2.784(4) A and for 4 3.184(4) A
Although the diffraction data for complex 5, containing pounds. This suggests that the tight ion-paired compound
perfluorooctylcarboxylate instead of trifluoroacetate, were 5 is also stable in such nonpolar solvents. This could be
insufficient for satisfactory refinement of all parameters, the explained by the interaction of the hydrophilic moieties, cat-
data show without doubt that the perfluorooctylcarboxyl- ionic 1,2-diamine and carboxylate with each other in such
ate is anchored via the two imidazole NH to the complex a way that only the lipophilic tert-butyl- and perfluorooctyl
˚
cation, as is similar in 4 (O1ϪN4 ϭ ca. 2.660 A, O2ϪN3 ϭ moieties interact with the solvent. In contrast, the ionic
˚
ca. 2.706 A). The structural motif of 5 is displayed in complex [(tbbpy)3Ru][OOC(CF2)7CF3]2, which can be ob-
Figure 7.
tained by simple anion-exchange, is completely insoluble in
Complex 5 contains a twofold positively charged cation scCO2. Due to the lack of NϪH functions in this complex
as part of the ion-paired unit but also a discrete anion. Sur- no hydrogen bonds can be formed, additionally confirming
prisingly, 5 is even soluble in supercritical CO2, which is that the supramolecular association via hydrogen bonds is
known to be an extremely poor solvent for ionic com- essential for this unexpected effect.
2804
Eur. J. Inorg. Chem. 2002, 2800Ϫ2809

Tight Ion Pair Complexes of Ruthenium and Iron
FULL PAPER
nected by the terephthalate bridge (Figure 9 and Scheme 4).
However, only the protonated imidazole nitrogen forms a
hydrogen bond to one oxygen of the carboxylate group
˚
[N3ϪO2 ϭ 2.693(5) A] whereas the deprotonated imidazole
nitrogen acts as a hydrogen bond acceptor for an additional
˚
water molecule [N4ϪO3 ϭ 2.871(5) A].
Figure 7. Structural motif of complex 5
Deprotonation of [(tbbpy)2Ru(bbimH2)](PF6)2 and sub-
sequent reaction with tetetrafluoroterephthalic acid in a
molar ratio 2:1 in acetone/water resulted in the formation
of complex 6. Upon recrystallization of 6 from acetonitrile/
water the deep red complex 7 was obtained. Both complexes
could be isolated as single crystals.
˚
Figure 9. Molecular structures of complex 7, selected distances [A]
and bond angles [deg]: O3ϪN4 2.871(5), O2ϪN3 2.693(4), O2ϪO3
2.926 (5), O1ϪC54 1.230(5), O2ϪC54 1.248(5); O1ϪC54ϪO2
127.9(4)
Figure 8 shows the molecular structure for compound 6
and lists relevant bond lengths and angles in the figure cap-
tions.
The ruthenium complexes are consequently twisted out
of the plane defined by the two carboxylate moieties by
65.0°. This is a difference of 87.8° compared with the value
obtained for 6. As expected, the Ru···Ru distance in 7
(2.025 nm) is longer than in 6 (1.957 nm). The isolated com-
pound 7 contains, as in 6, only the MESO isomer.
The dimeric arrangement is therefore stable even if the
essential ruthenium based NH functions are monodepro-
tonated.
Conclusion
˚
Tight ion-paired complexes with different anions can be
synthesized using diimine/diamine type bridging ligands,
which are able to split MϪX bonds under formation of a
coupled cation/anion coordination. The resulting ion-
Figure 8. Molecular structure of complex 6, selected distances [A]
and bond angles [deg]: O1ϪN3 2.673(5), O2ϪN4 2.652(5),
O1ϪC54 1.240(5), O2ϪC54 1.232(5); O1ϪC54ϪO2 128.5(4)
In the solid state two ruthenium bibenzimidazole units paired complexes can be considered as ‘‘protected metalloli-
are connected via a deprotonated tetrafluoroterephthalic gands’’ useful for the construction of oligonuclear organo-
acid dianion. Two PF6 anions remain isolated. Both imida- metallic complexes, as demonstrated by the reaction of 1a
zole based NH functions interact with both oxygen atoms with Pd(acac)2 resulting in the formation of the tetranuclear
of one carboxylate function, resulting in N···O distances of mixed metal complex 2. The hydrogen bonded anion in 1
˚
2.673(5) and 2.652(5) A, respectively. The interaction be- can be varied in a wide range. The novel hydrogen bonding
tween the ruthenium complex units and the carboxylate pattern displayed in 1a؊c between the cationic oxalic amid-
moiety is very similar to that observed in 4. Both ruthenium ine fragment and one specific spatially well defined point
complexes are twisted out of the plane defined by the two opens the possibility of designing supramolecular com-
coplanar carboxylate moieties by 152.8°. The Ru···Ru dis- pounds using new, ‘‘single point’’ bridging components
tance defined by this supramolecular arrangement is such as the redox active 1,4-benzoquinone and similar sys-
1.957 nm. Although the combination of two inherently tems.
chiral ruthenium complexes may lead to a mixture of dias-
tereomers[3] the crystals of 6 only contained the MESO iso- polypyridyl complexes employing supramolecular construc-
mer. tion principles is strongly reminiscent of the building prin-
The connection of chromophores such as ruthenium
According to the X-ray analysis of single crystals, 7 con- ciples of the naturally occurring Light Harvesting Com-
tains two monodeprotonated ruthenium units, also con- plexes (LHA). Additionally, the simple building blocks em-
Eur. J. Inorg. Chem. 2002, 2800Ϫ2809
2805

S. Rau, L. Böttcher, S. Schebesta, M. Stollenz, H. Görls, D. Walther
FULL PAPER
Scheme 4. Structural formula of complexes 6 and 7
C40H44Cl2N4Ru (752.8): calcd.: C 63.82, H 5.89, N 7.44, Cl 9.42;
ployed here, as in 6, would allow a wide variation of the
structures obtained, for example simply by switching the
coordination mode by altering the pH values. Furthermore,
the enhanced solubility of 5 offers the interesting possibility
of investigating reactions of the photoactive complex 5 and
related complexes in supercritical CO2. Further studies
along these lines are now in progress.
1
found C 63.52, H 6.23, N 7.05, Cl 9.24. H NMR ([D8]THF): δ ϭ
1.14, 1.17 [d, 3JH-H ϭ 6.9 Hz, 6 H, ϪCH(CH3)2 cymene], 2.09, 2.18
(2 s, 6 H each, ϪCH3 tolyl), 2.27 (s, 3 H, ϪCH3 cymene), 2.50 [five
3
lines, JH-H ϭ 7.0 Hz, 1 H, ϪCH(CH3)2 cymene], 4.55, 4.58, 4.60,
3
4.64 (2 d, JH-H ϭ 6.2 Hz, 2 H each, H2,3,5,6 cymene), 6.62, 6.66,
3
6.74, 6.78 [2 dAAЈBBЈ, JH-H ϭ 8.3 Hz, 6 H each, ϪCH tolyl), 7.02,
7.60 (2 sbroad, 2 H each, ϪCH tolyl), 12.83 (s, 2 H, ϪNH) ppm.
13C NMR ([D8]THF): δ ϭ 15.5 (ϪCH3 cymene), 20.9 (ϪCH3
tolyl), 22.6 (ϪCH(CH3)2 cymene), 31.0 [ϪCH(CH3)2 cymene],
84.8, 86.5 (C2,3,5,6 cymene), 102.0, 104.3 (C1,4 cymene), 123.9,
126.2, 128.6, 129.3 (CH tolyl), 124.7, 126.3 (CϪCH3 tolyl), 138.3
(NHϪC tolyl), 148.8 (ϭNϪC tolyl), 155.6 (Cbridge) ppm. MS (ESI
in THF): m/z (%) ϭ 716 (100) [M Ϫ Cl]ϩ, 680 (20) [M Ϫ 2 Cl]ϩ.
Experimental Section
General: p-Tolyl oxalic amidine ligand (oxam1);[30] the ligand N,NЈ-
bis(2-pyridylmethyl)-1,2-bis(2,4,6-trimethylphenylimino)ethane-
1,2-diamine (oxam2),[20,31] and [(tbbpy)2Ru]Cl2 and [(tbbpy)2Ru-
(bbimH2)](X)2 (X ϭ Cl, PF6)[3,29] were prepared according to de-
The red-orange complex 1b was prepared by reaction of 1a in THF
with equimolar amounts of NaBF4. yield: 80% C40H44BClF4N4Ru
(804.2) calcd.: C 59.74, H 5.52, N 6.97; found C 58.63, H 5.43, N
scribed
methods.
The
complexes
(η6-p-cymene)RuCl2,
PdCl2(CH3CN)2, and trifluoroacetic acid (Aldrich) and perfluoro-
octylcarboxylic acid (ABCR) were used without additional puri-
fication. All manipulations were carried out under Argon using
standard Schlenk techniques and the solvents used were dried
and distilled.
3
6.53. 1H NMR ([D8]THF): δ ϭ 1.13, 1.17 [d, JH,H ϭ 6.9 Hz, 6 H,
ϪCH(CH3)2 cymene], 2.10 (s, 12 H, ϪCH3 tolyl), 2.19 (s, 3 H,
3
ϪCH3 cymene), 2.63 [m, JH,H ϭ 6.8 Hz, 1 H, ϪCH(CH3)2 cy-
mene], 4.63 (s, 4 H, H2,3,5,6 cymene), 6.69, 6.84, 6.96, 7.17, 7.50
(four broad signals, one s, 16 H overall, ϪCH tolyl), 9.05 (sbroad, 2
H, ϪNH) ppm. 13C NMR ([D8]THF): δ ϭ 15.9 (ϪCH3 cymene),
20.7 (ϪCH3 tolyl), 22.5 [ϪCH(CH3)2 cymene], 31.7 [ϪCH(CH3)2
cymene], 84.7, 87.3 (C2,3,5,6 cymene), 102.0, 104.3 (C1,4 cymene),
123.7, 128.8 (CH tolyl), 134.2 (CϪCH3 tolyl), 136.5 (NHϪC tolyl),
149.7 (ϭNϪC tolyl), 156.7 (Cbridge).
1H NMR and 13C NMR spectra were recorded at ambient temper-
ature unless otherwise stated on a Bruker AC 200 MHz spectro-
meter. All spectra were referenced to TMS or deuterated solvent as
an internal standard. FAB-mass spectra were obtained on a Finni-
gan MAT SSQ 710 system (2,4-dimethoxybenzyl alcohol as mat-
rix), ESI-mass spectra were recorded on a Finnigan MAT, MAT
95 XL. IR measurements were carried out on a PerkinϪElmer Sys-
tem 2000 FT-IR.
Analogously, 1c was synthesized by reaction of 1a in THF with
an equimolar quantity of Ag(OOCCF3). yield: nearly quantitative
C42H44ClF3N4O2Ru (830.4) calcd.: C 60.75 H 5.33 N 6.75 Cl 4.27
Complex 1a: A solution of oxam1 (1.30 g, 2.92 mmol) in toluene
(30 mL) was added to a suspension of [(η6-p-cymene)RuCl2]2
(0.89 g, 1.46 mmol) in toluene (30 mL) and the mixture was re-
fluxed for 2 hours. After cooling to room temperature, the orange-
red microcrystalline solid was filtered, washed with diethyl ether
(20 mL) and dried in vacuo. Single crystals of 1 were obtained by
1
found C 60.01 H 5.13 N 6.44. H NMR ([D8]THF): δ ϭ 1.14, 1.18
[d, 3JH,H ϭ 6.9 Hz, 6 H, ϪCH(CH3)2 cymene], 2.10 (s, 12 H, ϪCH3
tolyl), 2.18 (s, 3 H, ϪCH3 cymene), 2.51 [m, 1 H, ϪCH(CH3)2
cymene], 4.57, 4.60, 4.62, 4.65 (s, 1 H each, 3JH,H ϭ 4.3 Hz, H2,3,5,6
cymene), 6.67, 6.87, 7.56 (m, 16 H, ϪCH tolyl), 11Ϫ12 (svery broad
,
recrystallization from hot toluene. Yield: 1.75 g (79%). 2 H, ϪNH).
2806
Eur. J. Inorg. Chem. 2002, 2800Ϫ2809

Tight Ion Pair Complexes of Ruthenium and Iron
FULL PAPER
Single crystals of these complexes, suitable for an X-ray diffraction
analysis, were obtained from THF or toluene.
MS (ESI in methanol): m/z (%) ϭ 871 (100) [M Ϫ H Ϫ PF6
CF3COO]ϩ (isotope pattern found) IR (Nujol): ν˜ ϭ 3060 (m, NH),
1776 (s, CϭO), 1614 (s, CϭN) cmϪ1
Ϫ
.
Complex 2: Complex 1 (0.38 g, 0.5 mmol) and Pd(acac)2 (0.154 g,
0.5 mmol) were suspended in toluene (20 mL) and refluxed for 4 h
or until a clear, dark red solution resulted. The solution was con-
centrated to 5 mL and pentane (20 mL) was added. The red micro-
crystalline solid was filtered, washed with pentane (20 mL) and
dried in vacuo. Single crystals of 2 were obtained by recrystalliza-
tion from diethyl ether or toluene. Yield: 0.28 g (65%).
C80H84Cl4N8Pd2Ru2 (1714.35) calcd.: C 56.04, H 4.94, N 6.53, Cl
Complex 5: [(tbbpy)2Ru(bbimH2)](Cl)2 (405 mg, 0.43 mmol) was
dissolved in predistilled THF. Freshly prepared NaOMe
(0.87 mmol) in MeOH was then added, resulting in a bathochromic
shift of the absorption. The solution was stirred for 30 min.
C7F15COOH (358 mg, 0.87 mmol) was added to this solution,
which resulted in a hypsochromic shift of the absorption, the solu-
tion was stirred for 20 min, the solvent removed and the precipitate
1
1
recrystallized from acetone/water. H NMR spectra were recorded
8.27; found C 55.63, H 5.49, N 5.90, Cl 8.25. H NMR (400 MHz,
in deuterated acetone. Yield 705 mg, 92%, 1H NMR ([D6]acetone):
δ ϭ 16.4 (s, 1 H, NH), 8.85 (s, 2 H, 3a-H), 8.75 (s, 2 H, 3b-H),
8.04 (m, 2 H, 6a-H), 8.04 (m, 2 H, 6b-H), 7.76 (d, 2 H, 6-H), 7.61
(d, 2 H, 5a-H), 7.45 (d, 2 H, 5b-H), 7.37 (t, 2 H, 5-H) 7.01 (t, 2 H,
4-H), 5.72 (d, 2 H, 3-H), 1.47 (s, 18 H, C4H9), 1.35 (s, 18 H, C4H9)
ppm. MS (ESI in methanol): m/z (%) ϭ 871 (100) [M Ϫ H Ϫ
2 C7F15COO]ϩ (isotope pattern found) IR (Nujol): ν˜ ϭ 3060 (m,
3
[D8]THF): δ ϭ 1.11, 1.13 [d, JH-H ϭ 6.9 Hz, 6 H, ϪCH(CH3)2
cymene], 2.00 (s, 24 H, ϪCH3 tolyl), 2.09 (s, 6 H, ϪCH3 cymene),
3
2.43 [m, JH-H ϭ 7.0 Hz, 2 H, ϪCH(CH3)2 cymene], 4.07, 4.09,
3
4.21, 4.23 (2 d, JH-H ϭ 5.9 Hz, 4 H each, H2,3,5,6 cymene), 6.45,
3
6.47, 6.49, 6.51 (2 dAAЈBBЈ, JH-H ϭ 8.0 Hz, 8 H each, ϪCH tolyl),
3
6.65, 6.68, 7.22, 7.24 (2 dAAЈBBЈ, JH-H ϭ 8.0 Hz, 8 H each, ϪCH
tolyl) ppm. 13C NMR (100.6 MHz, [D8]THF): δ ϭ 19.0 (ϪCH3
cymene), 20.8, 21.0 (2 s, ϪCH3 tolyl), 22.7 [ϪCH(CH3)2 cymene],
31.5 [ϪCH(CH3)2 cymene], 82.7, 85.5 (C2,3,5,6 cymene), 100.2,
101.6 (C1,4 cymene), 125.9, 127.5, 127.7, 128.6 (CH tolyl), 132.9,
NH), 1730 (s, CϭO), 1612 (s, CϭN) cmϪ1
.
Complex 6: [(tbbpy)2Ru(bbimH2)](PF6)2 (500 mg, 0.43 mmol) was
dissolved in THF. Freshly prepared NaOMe (0.43 mmol) in MeOH
was then added, resulting in a bathochromic shift of the color.
After stirring for 20 min COOHC6F4COOH (0.43 mmol, 103 mg)
was added to this solution resulting in a hypsochromic shift of the
color. The solution was then stirred for 20 min, the solvent removed
and the precipitate recrystallized from acetone/water. Yield 404 mg,
75%, 1H NMR ([D6]acetone): δ ϭ 8.85 (s, 2 H, 3a-H), 8.75 (s, 2 H,
3b-H), 8.04 (m, 2 H, 6a-H), 8.04 (m, 2 H, 6b-H), 7.76 (d, 2 H, 6-
H), 7.61 (d, 2 H, 5a-H), 7.45 (d, 2 H, 5b-H), 7.37 (t, 2 H, 5-H) 7.01
(t, 2 H, 4-H), 5.72 (d, 2 H, 3-H), 1.47 (s, 18 H, C4H9), 1.35 (s, 18
H, C4H9) ppm. MS (ESI in methanol): m/z (%) ϭ 871 (100) [M Ϫ
(tbbpy)2Ru(bbimH2) Ϫ H Ϫ 2 PF6 Ϫ COOC6F4COO]ϩ (isotope
pattern found) IR (Nujol): ν˜ ϭ 3410 (w, OH), 3177 (m, NH), 1704
133.3 (CϪCH3 tolyl), 144.7, 151.1 (ϪNϪC tolyl), 167.8 (Cbridge
)
ppm. MS (ESI in toluene ϩ methanol): m/z (%) ϭ 1679 (46) [M Ϫ
Cl]ϩ (isotope pattern found), 854 (100) [M Ϫ C40H42N4Cl2RuPd]ϩ,
680 [M Ϫ C40H42N4Cl4Pd2Ru]ϩ.
Complex 3a: This compound was prepared as a crystalline bright
orange solid analogously to 3b from FeCl2 (66 mg, 0.52 mmol) us-
ing N,NЈ-bis(2-pyridylmethyl)-1,2-bis(2,4,6-trimethylphenylimino)-
ethane-1,2-diamine (oxam2) (262 mg, 0.52 mmol). Single crystals
suitable for X-ray determination were obtained from THF. Yield:
286 mg (87%). C36H44Cl2FeN6O (703.6) calcd.: C 61.46, H 6.30, N
11.95; found C 61.91, H 6.55, N 12.15. MS (FAB in NBA): m/z
(%) ϭ 630 (1) [M]ϩ, 595 (58) [M Ϫ Cl]ϩ, 560 (33) [M Ϫ 2 Cl]ϩ,
559 (83) [M Ϫ 2 Cl]ϩ.
(m, CϭO), 1613 (s, CϭN) cmϪ1
.
Complex 7: Compound 6 (200 mg) was dissolved in acetonitrile/
water (80:20). The color of the solution changed from bright or-
ange to red. The solvent was allowed to evaporate slowly and the
small crystals that appeared were collected by filtration. X-ray suit-
able crystals were obtained by recrystallization from acetonitrile/
Complex 3b: FeBr2·2THF (181 mg, 0.50 mmol) and N,NЈ-bis(2-pyr-
idylmethyl)-1,2-bis(2,4,6-trimethylphenylimino)ethane-1,2-diamine
(oxam2) (261 mg, 0.52 mmol) were dissolved in THF (40 mL) and
stirred overnight, at room temperature. After concentrating the so-
lution to 10 mL, the precipitate was filtered off, washed with THF
(3 ϫ 10 mL) and dried by oil pump vacuum (9 h) at room temper-
ature. A light orange solid was obtained. Yield: 317 mg (88%).
Single crystals suitable for X-ray-determination were obtained from
THF. C32H36Br2FeN6 (720.33): calcd. C 53.36; H 5.04; N 11.67;
found C 52.44; H 5.22; N 11.07. IR (Nujol): ν˜ ϭ 3127 (m, NH),
1605, 1622, 1554 cmϪ1. MS (FAB in NBA): m/z (%) ϭ 639 (17) [M
Ϫ Br]ϩ, 560 (14)[M Ϫ 2 Br]ϩ, 559 (83)[M Ϫ 2 BrϪH]ϩ.
1
water. Yield 110 mg 55%, H NMR ([D6]acetonitrile): δ ϭ 8.51 (s,
2 H, 3a-H), 8.42 (s, 2 H, 3b-H), 7.87 (d, 2 H, 6a-H), 7.76 (m, 4 H,
6b/6-H), 7.48 (d, 2 H, 5a-H), 7.43 (t, 2 H, 5-H) 7.35 (d, 2 H, 5b-
H), 7.06 (t, 2 H, 4-H), 5.68 (d, 2 H, 3-H), 1.47 (s, 18 H, C4H9),
1.35 (s, 18 H, C4H9) ppm. MS (ESI in methanol): m/z (%) ϭ 871
(100) [M Ϫ (tbbpy)2Ru(bbimH2) Ϫ H Ϫ COOC6F4COO]ϩ (isotope
pattern found) IR (Nujol): ν˜ ϭ 3460 (m, OH), 3177 (m, NH), 1674
(m, CϭO), 1607 (s, CϭN) cmϪ1
.
Complex 4: [(tbbpy)2Ru(bbimH2)](PF6)2 (500 mg, 0.43 mmol) was
(tbbpy)3Ru(C7F15COO)2: Triethylamine (45 mg, 0.44 mmol) was
dissolved in predistilled THF. Freshly prepared NaOMe
added to a solution of perfluorooctanoic acid (177 mg, 0.44 mmol)
(0.43 mmol) in MeOH was then added, resulting in a bathochromic in CH2Cl2 while stirring. After 15 minutes this solution was poured
shift of the absorption. The solution was stirred for 20 min. into a suspension of [(tbbpy)3Ru](PF6)2 (250 mg, 0.21 mmol in
CF3COOH (49 mg, 0.43 mmol,) was added to this solution, which CH2Cl2/H2O, 50:50). This mixture was stirred rapidly for 48 hours.
resulted in a hypsochromic shift of absorption, the solution was
stirred for 20 min, the solvent removed and the precipitate recrys-
The bright orange-red organic layer was separated and the solvent
was removed. The remaining solid was recrystallized from acetone/
tallized from acetone/water resulting in single crystals. 1H NMR water (10:1). The absence of the PF6Ϫ anion was established via 31
P
spectra were recorded in deuterated acetone. Yield: 410 mg (84.4%).
NMR spectroscopy. Yield 363 mg, quantitative C70H72F30O4N6Ru
C55H64F9N8O3PRu (1188.21): calcd. C 55.59, H 5.43, N 9.43; (1732.4) calcd.: C 48.53, H 4.19, N 4.85 found C 46.33, H 3.93, N
1
found C 55.87, H 5.13, N 8.84. H NMR ([D6]acetone): δ ϭ 16.4
(s, 1 H, NH), 8.85 (s, 2 H, 3a-H), 8.75 (s, 2 H, 3b-H), 8.04 (m, 2 CH3), 7.436 (dd, 1 H, CH-arom.), 7.605 (d, 1 H, CH-arom.), 8.529
H, 6a-H), 8.04 (m, 2 H, 6b-H), 7.76 (d, 2 H, 6-H), 7.61 (d, 2 H, (s, 1 H, CH-arom.) ppm. IR (Nujol): ν˜ ϭ 1695 (s, CϭO), 1237,
5a-H), 7.45 (d, 2 H 5b-H), 7.37 (t, 2 H, 5-H) 7.01 (t, 2 H, 4-H), 1202 cmϪ1 (s, CF). MS (ESI in methanol): m/z (%) ϭ 1319 (100)
4.42. 1H NMR (298 K, 400 MHz, CD2Cl2): δ ϭ 1.410 (s, 9 H,
5.72 (d, 2 H, 3-H), 1.47 (s, 18 H, C4H9), 1.35 (s, 18 H, C4H9) ppm.
[M Ϫ C7F15COO ϩ 1]ϩ, 905 (16) [M Ϫ 2 C7F15COO]ϩ.
Eur. J. Inorg. Chem. 2002, 2800Ϫ2809
2807

S. Rau, L. Böttcher, S. Schebesta, M. Stollenz, H. Görls, D. Walther
FULL PAPER
Crystal Structure Determination: The intensity data for the com-
pounds were collected on a NoniusϪKappa CCD diffractometer,
pendent reflections, Rint ϭ 0.028, 8442 reflections with Fo Ͼ 4σ(Fo),
559 parameters, 0 restraints, R1obs ϭ 0.048, wR2obs ϭ 0.120, R1all ϭ
using graphite-monochromated Mo-Kα radiation. Data were cor- 0.062, wR2all ϭ 0.134, GOOF ϭ 1.099, largest difference peak and
Ϫ3
˚
rected for Lorentz and polarization effects, but for absorption were
only corrected for 3b.[32,33] The structures were solved by direct
methods (SHELXS[34]) and refined by full-matrix least-squares
techniques against F2o (SHELXL-97[35]). The diffraction data ob-
tained for compound 5 were insufficient for satisfactory refinement
of the structure parameters. However, the data were sufficient to
show the structural motif of the molecule (Figure 7), the hydrogen-
bridging system, and the crystallographic data. The data for com-
pound 5 were not deposited in the Cambridge Crystallographic
Data Centre.
hole: 1.328/Ϫ0.865 e·A
.
Crystal Data for 3a:[36] C32H36Cl2FeN6·C4H8O, Mr ϭ 703.52
g·molϪ1, orange prism, size 0.10 ϫ 0.09 ϫ 0.08 mm, monoclinic,
space group P21/c, a ϭ 9.7875(2), b ϭ 13.6051(3), c ϭ 27.9561(5)
3
˚
˚
A, β ϭ 98.710(1)°, V ϭ 3679.70(13) A , T ϭ Ϫ90 °C, Z ϭ 4,
ρcalcd. ϭ 1.270 g·cmϪ3, µ(Mo-Kα) ϭ 5.91 cmϪ1, F(000) ϭ 1480,
27538 reflections in h (Ϫ12/12), k (Ϫ17/17), l (Ϫ36/35), measured
in the range 2.10° Յ Θ Յ 27.46°, completeness Θmax ϭ 99.3%, 8375
independent reflections, Rint ϭ 0.066, 6324 reflections with Fo Ͼ
4σ(Fo), 411 parameters, 10 restraints, R1obs ϭ 0.060, wR2obs
ϭ
0.165, R1all ϭ 0.081, wR2all ϭ 0.184, GOOF ϭ 1.020, largest differ-
For all compounds the hydrogen atoms of the diamine groups and
the hydrogen atoms of the water molecule of 7 were located by
difference Fourier synthesis and refined isotropically. All other hy-
drogen atoms were included at calculated positions with fixed ther-
mal parameters. All non-hydrogen atoms (without the acetone and
the disordered [PF6]Ϫ) were refined anisotropically.[36] XP (SIE-
MENS Analytical X-ray Instruments, Inc.) was used for structure
representations.
Ϫ3
˚
ence peak and hole: 0.931/Ϫ0.577 e·A
.
Crystal Data for 3b:[36] C32H36Br2FeN6·2.5C4H8O, Mr ϭ 900.60
g·molϪ1, red-brown prism, size 0.08 ϫ 0.08 ϫ 0.06 mm, triclinic,
˚
3
¯
space group P1, a ϭ 15.9361(7), b ϭ 18.4001(8), c ϭ 18.5403(6) A,
˚
α ϭ 97.792(3), β ϭ 113.089(3), γ ϭ 108.091(2)°, V ϭ 4543.2(3) A ,
Tϭ Ϫ90 °C, Z ϭ 4, ρcalcd. ϭ 1.317 g·cmϪ3, µ(Mo-Kα) ϭ 21.31
cmϪ1
,
semi-empirical, transmin: 0.5701, transmax: 0.6280,
Crystal Data for 1a:[36] C40H44Cl2N4Ru, Mr ϭ 752.76 g·molϪ1, or-
ange prism, size 0.10 ϫ 0.10 ϫ 0.09 mm, monoclinic, space group
F(000) ϭ 1864, 34660 reflections in h (Ϫ20/20), k (Ϫ22/23), l (Ϫ24/
22), measured in the range 2.59° Յ Θ Յ 27.42°, completeness
Θmax ϭ 91.2%, 18862 independent reflections, Rint ϭ 0.067, 10654
reflections with Fo Ͼ 4σ(Fo), 929 parameters, 0 restraints, R1obs. ϭ
0.095, wR2obs. ϭ 0.232, R1all ϭ 0.169, wR2all ϭ 0.286, GOOF ϭ
˚
P21/n, a ϭ 12.0053(3), b ϭ 18.2083(4), c ϭ 17.2697(3) A, β ϭ
3
˚
95.763(2)°, V ϭ 3756.01(14) A , Tϭ Ϫ90 °C, Z ϭ 4, ρcalcd. ϭ 1.331
g·cmϪ3, µ(Mo-Kα) ϭ 5.92 cmϪ1, F(000) ϭ 1560, 15215 reflections
in h (Ϫ15/15), k (Ϫ23/21), l (Ϫ22/22), measured in the range 2.27°
Յ Θ Յ 27.50°, completeness Θmax ϭ 98.8%, 8535 independent
reflections, Rint ϭ 0.036, 7120 reflections with Fo Ͼ 4σ(Fo), 427
Ϫ3
˚
1.034, largest difference peak and hole: 2.981/Ϫ1.214 e·A
.
Crystal Data for 4:[36] [C50H58N8Ru(C2F3O2)][PF6]·C3H6O, Mr ϭ
1188.18 g·molϪ1, orange prism, size 0.12 ϫ 0.10 ϫ 0.10 mm, mono-
clinic, space group P21/n, a ϭ 16.499(3), b ϭ 18.947(4), c ϭ
parameters, 0 restraints, R1obs. ϭ 0.0547, wR2obs. ϭ 0.142, R1all
ϭ
0.067, wR2all ϭ 0.152, GOOF ϭ 1.085, largest difference peak and
3
˚
˚
Ϫ3
˚
18.518(4) A, β ϭ 99.09(3)°, V ϭ 5716(2) A , T ϭ Ϫ90 °C, Z ϭ 4,
ρcalcd. ϭ 1.381 g·cmϪ3, µ(Mo-Kα) ϭ 3.81 cmϪ1, F(000) ϭ 2456,
46833 reflections in h (Ϫ20/21), k (Ϫ23/24), l (Ϫ21/24), measured
in the range 2.10° Յ Θ Յ 27.51°, completeness Θmax ϭ 98%, 12884
independent reflections, Rint ϭ 0.089, 7991 reflections with Fo Ͼ
hole: 1.219/Ϫ1.074 e·A
.
Crystal Data for 1b:[36] [C40H44ClN4Ru(BF4)], Mr ϭ 804.12
g·molϪ1, red-orange prism, size 0.10 ϫ 0.10 ϫ 0.03 mm, ortho-
rhombic, space group P212121, a ϭ 11.0377(2), b ϭ 18.0910(3), c ϭ
3
˚
˚
4σ(Fo), 673 parameters, 36 restraints, R1obs. ϭ 0.072, wR2obs.
ϭ
19.2852(4) A, V ϭ 3850.93(12) A , Tϭ Ϫ90 °C, Z ϭ 4, ρcalcd.
ϭ
1.387 g·cmϪ3, µ(Mo-Kα) ϭ 5.29 cmϪ1, F(000) ϭ 1656, 8625
reflections in h (Ϫ14/14), k (Ϫ23/23), l (Ϫ24/25), measured in the
range 2.41° Յ Θ Յ 27.47°, completeness Θmax ϭ 98.7%, 8625 inde-
pendent reflections, Rint ϭ 0.042, 8018 reflections with Fo Ͼ 4σ(Fo),
466 parameters, 0 restraints, R1obs ϭ 0.032, wR2obs ϭ 0.079, R1all ϭ
0.037, wR2all ϭ 0.084, GOOF ϭ 1.036, Flack-parameter Ϫ0.04(2),
0.205, R1all ϭ 0.114, wR2all ϭ 0.224, GOOF ϭ 1.336, largest differ-
Ϫ3
˚
ence peak and hole: 1.452/Ϫ1.101 e·A
.
Crystal Data for 5: [C50H58N8Ru(C7F15COO)](C7F15COO), Mr ϭ
1578.17 g·molϪ1, red-brown prism, size 0.20 ϫ 0.18 ϫ 0.12 mm,
¯
triclinic, space group P1, a ϭ 15.880(3), b ϭ 21.334(4), c ϭ
˚
Ϫ3
˚
29.081(6) A, α ϭ 75.96(3), β ϭ 88.66(3), γ ϭ 86.98(3)°, V ϭ 9544(3)
largest difference peak and hole: 0.484/Ϫ0.501 e·A
.
3
A , T ϭ Ϫ90 °C, Z ϭ 4, ρcalcd. ϭ 1.098 g·cmϪ3, µ(Mo-Kα) ϭ 2.58
˚
Crystal Data for 1c:[36] [C40H44ClN4O2Ru(CF3COO)], Mr ϭ 830.33
gmolϪ1, red-orange prism, size 0.10 ϫ 0.10 ϫ 0.05 mm, triclinic,
cmϪ1, F(000) ϭ 3184, 43889 reflections in h (Ϫ20/20), k (Ϫ27/22), l
(Ϫ35/36), measured in the range 1.07° Յ Θ Յ 27.47°, completeness
Θmax ϭ 78%, 34097 independent reflections.
˚
3
¯
space group P1, a ϭ 10.9028(8), b ϭ 13.4278(8), c ϭ 13.5573(9) A,
˚
α ϭ 92.835(5), β ϭ 93.959(4), γ ϭ 93.280(4)°, V ϭ 1974.0(2) A ,
Crystal Data for 6:[36] [(C50H58N8Ru)2{C4F4(COO)2}](PF6)2·
3(CH3)2CO, Mr ϭ 2462.50 g·molϪ1, red-brown prism, size 0.10 ϫ
Tϭ Ϫ90 °C, Z ϭ 2, ρcalcd. ϭ 1.397 g·cmϪ3, µ(Mo-Kα) ϭ 5.19 cmϪ1
,
F(000) ϭ 856, 13866 reflections in h (Ϫ14/11), k (Ϫ15/17), l (Ϫ16/
17), measured in the range 1.88° Յ Θ Յ 27.46°, completeness
Θmax ϭ 98.7%, 8921 independent reflections, Rint ϭ 0.042, 6350
¯
0.09 ϫ 0.08 mm, triclinic, space group P1, a ϭ 13.6330(4), b ϭ
˚
14.2867(5), c ϭ 16.7479(5) A, α ϭ 98.356(2), β ϭ 94.201(2), γ ϭ
3
˚
100.148(2)°, V ϭ 3160.47(17) A , T ϭ Ϫ90 °C, Z ϭ 2, ρcalcd.
ϭ
reflections with Fo Ͼ 4σ(Fo), 486 parameters, 0 restraints, R1obs
ϭ
1.294 g·cmϪ3, µ(Mo-Kα) ϭ 3.46 cmϪ1, F(000) ϭ 1276, 20848
reflections in h (Ϫ17/17), k (Ϫ14/18), l (Ϫ21/21), measured in the
range 3.07° Յ Θ Յ 27.47°, completeness Θmax ϭ 96.3%, 13947
independent reflections, Rint ϭ 0.028, 11364 reflections with Fo Ͼ
4σ(Fo), 731 parameters, 1 restraints, R1obs. ϭ 0.060, wR2obs ϭ 0.159,
R1all ϭ 0.078, wR2all ϭ 0.1775, GOOF ϭ 1.055, largest difference
0.059, wR2obs ϭ 0.128, R1all ϭ 0.097, wR2all ϭ 0.148, GOOF ϭ
Ϫ3
˚
1.037, largest difference peak and hole: 0.634/Ϫ0.701 e·A
.
Crystal Data for 2:[36] C80H84Cl4N8Pd2Ru2·4C7H8, Mr ϭ 2082.83
g·molϪ1, black-red prism, size 0.10 ϫ 0.09 ϫ 0.06 mm, monoclinic,
space group P21/c, a ϭ 13.6852(4), b ϭ 18.2930(7), c ϭ 19.9623(7)
3
˚
˚
A, β ϭ 101.706(2)°, V ϭ 4893.5(3) A , Tϭ Ϫ90 °C, Z ϭ 2, ρcalcd. ϭ
1.414 g·cmϪ3, µ(Mo-Kα) ϭ 8.25 cmϪ1, F(000) ϭ 2136, 14535
reflections in h (Ϫ15/17), k (Ϫ20/23), l (Ϫ25/25), measured in the
Ϫ3
˚
peak and hole: 1.351/Ϫ0.589 e·A
.
Crystal Data for 7:[36] [(C50H59N8Ru)2{C4F4(COO)2}][C4F4-
range 3.74° Յ Θ Յ 27.46°, completeness Θmax ϭ 88.8%, 9942 inde- (COO)2]·H2O·3CH3CN, Mr ϭ 2155.50 g·molϪ1, red-brown prism,
2808
Eur. J. Inorg. Chem. 2002, 2800Ϫ2809

Tight Ion Pair Complexes of Ruthenium and Iron
FULL PAPER
S. Rau, T. Büttner, C. Temme, M. Ruben, H. Görls, D. Walther,
M. Duati, F. Fanni, J. G. Vos, Inorg. Chem. 2000, 39,
1621Ϫ1624.
[17]
¯
size 0.12 ϫ 0.10 ϫ 0.09 mm, triclinic, space group P1, a ϭ
˚
10.3448(2), b ϭ 15.5248(4), c ϭ 19.5865(5) A, α ϭ 88.110(1), β ϭ
3
˚
78.075(1), γ ϭ 70.915(1) °, V ϭ 2906.52(12) A , T ϭ Ϫ90 °C, Z ϭ
1, ρcalcd. ϭ 1.231 g·cmϪ3, µ(Mo-Kα) ϭ 3.26 cmϪ1, F(000) ϭ 1126,
20157 reflections in h (Ϫ12/13), k (Ϫ19/17), l (Ϫ22/25), measured
in the range 7.07° Յ Θ Յ 27.45°, completeness Θmax ϭ 95.3%,
12680 independent reflections, Rint ϭ 0.033, 10139 reflections with
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ϭ
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Ϫ3
˚
ence peak and hole: 1.171/Ϫ0.567 e·A
.
Acknowledgments
Financial support for this work from the Deutsche Forschungsge-
meinschaft (SFB 436), and the Fonds der Chemischen Industrie is
gratefully acknowledged.
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Received March 28, 2002
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Eur. J. Inorg. Chem. 2002, 2800Ϫ2809
2809