Formation and structural studies of iron(III) and ruthenium(II) complexes of 1,4,7-triazacyclononane and N-monofunctionalised 1,4,7-triazacyclononane

Article abstract of DOI:10.1016/j.ica.2003.07.002

A series of 1,4,7-triazacyclononane derivatives of Fe(III) and Ru(II) have been investigated. The objective of this work was to investigate the effect of changing the functionality of a pendant group in order to create different Ru(II) and Fe(III) environments. From these studies, some interesting features are elucidated and different stacking properties arise due to the intra- and intermolecular X-HCl (X=O, N) interactions for the Fe(III) and Ru(II) complexes.

Full text of DOI:10.1016/j.ica.2003.07.002

Inorganica Chimica Acta 357 (2004) 689–698
www.elsevier.com/locate/ica
Formation and structural studies of iron(III) and
ruthenium(II) complexes of 1,4,7-triazacyclononane and
N-monofunctionalised 1,4,7-triazacyclononane
*
Andrew L. Gott, Patrick C. McGowan , Thomas J. Podesta, Christopher W. Tate
Department of Chemistry, University of Leeds, Leeds LS2 9JT, UK
Received 23 April 2003; accepted 8 July 2003
Abstract
A series of 1,4,7-triazacyclononane derivatives of Fe(III) and Ru(II) have been investigated. The objective of this work was to
investigate the effect of changing the functionality of a pendant group in order to create different Ru(II) and Fe(III) environments.
From these studies, some interesting features are elucidated and different stacking properties arise due to the intra- and intermo-
lecular X–Hꢀ ꢀ ꢀCl (X ¼ O, N) interactions for the Fe(III) and Ru(II) complexes.
Ó 2003 Elsevier B.V. All rights reserved.
1. Introduction
cluding the selective oxidation of alcohols and ketones
[17,18].
Several naturally occurring enzymes have been found
to contain an iron–oxygen–iron arrangement [1–3].
Many compounds have been synthesised in an attempt
to model this type of motif, using several types of ligand
system to ÔcapÕ the ends of the metal core [4]. On a re-
lated theme, there have been some papers published on
modelling the extradiol oxidative cleavage of catechol by
the iron enzymes catechol dioxygenases [5–9]. Reported
in one paper is the use of FeCl2/tacn/pyridine/O2/MeOH
mixture in the extradiol ring cleavage [9]. A number of
reactive intermediates have been purported for these
types of reactions and the results reported in this paper
may have some bearing on possible intermediates in the
reaction mechanism [9].
Work on ruthenium tacn complexes has been driven
by interest in terms of their coordination chemistry,
redox behaviour and electrochemistry, and also as a
spectator ligand in the study of ‘‘non-innocent’’ donor
ligands [10–13]. Also, the chemistry of a wide range of
organometallic compounds containing the ruthenium
tacn moiety have been investigated [14–16], which can
exhibit catalytic properties in a variety of systems, in-
Herein we report the synthesis and structural studies
of a number of Fe(III)l-oxo derivatives chloride N-
monofunctionalised 1,4,7-triazacyclononane systems.
Variation of the coordinating capability of the pendant
arm has a dramatic effect on the structure of the oxidised
Fe(III) species. One of the Fe(II) precursors to these
compounds has been published previously [19] and here
this paper represents an exploration into some of the
reactivity of the Fe(II) complexes and formation of new
Ru(II) complexes. Not only is the discovery of new
synthetic routes for ruthenium tacn important but con-
trolling the reaction conditions to produce the desired
product is crucial. One of the controlling mechanisms is
the reliance on the hydrogen bonding capability of the
N–H groups of the triazacyclononane ligand in transi-
tion metal complexes [20].
2. Results and discussion
2.1. Synthesis and characterisation
The iron(III) tacn derivatives can be synthesised
through one of two methods. The compound [bis(1-(2-
methylpyridyl)-1,4,7-triazacyclononane iron(III)chloride)-
* Corresponding author. Fax: +44-0113-2336565.
E-mail address: p.c.mcgowan@chem.leeds.ac.uk (P.C. McGowan).
0020-1693/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2003.07.002

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A.L. Gott et al. / Inorganica Chimica Acta 357 (2004) 689–698
l-oxo]dichloride (1), was synthesised by stirring a solution
of [1-(2-methylpyridyl)-1,4,7-triazacyclononane]iron(II)-
dichloride in dichloromethane overnight in air (Scheme 1).
During this time the product precipitated from the solution
as a brown powder, which was isolated by filtration.
Compound 1 was characterised by microanalysis, mass
spectrometry, infrared spectroscopy and X-ray crystallog-
raphy.
The compound bis[1-(prop-3-ene)-1,4,7-triazacyclo-
nonane iron(III)dichloride]l-oxide (2), was prepared by
heating a suspension of anhydrous iron(II) chloride in
THF with a solution of 1-(propene)-1,4,7-triazacyclo-
nonane to reflux for 7 days in air (Scheme 2). The sol-
vent was removed under reduced pressure and the
product extracted with dichloromethane. The product
was obtained as a green powder upon removal of the
dichloromethane. The product was characterised by
microanalysis, infrared spectroscopy, mass spectrometry
and X-ray crystallography. Green crystals of 2, suitable
for X-ray diffraction were grown by diffusing petrol into
a dichloromethane solution of the compound. After
repeated attempts, the isolation of the Fe(II) product
with 1-(propene)-1,4,7-triazacyclononane did not prove
possible.
complexes is an intense band at m ¼ 801 cmꢁ1 for 1
and m ¼ 806 cmꢁ1 for 2. This is assigned to the band mas
Fe–O–Fe and is characteristic for l-oxo bridged iron
complexes [3].
It is interesting to compare complexes 1 and 2. For
complex 1, the nitrogen remains bound to the iron
centre after oxidation leading to the formation of a di-
cationic binuclear complex. Complex 2 is different since
the pendant alkene arms do not interact with the either
of the metal centres and the oxidised complex is neutral.
The most prominent feature of the two complexes is the
iron–oxygen–iron core. This type of bridging arrange-
ment is commonly found in bio- and experimental in-
organic chemistry. Among these systems, there are
several examples of triazacyclononane ligands being
used. Most of the model complexes synthesised contain
not only the bridging oxygen atom, but also one or two
bridging types, such as l-hydroxyl, l-carboxylato and l-
acetato [21–24]. There are fewer examples of systems
with only one oxygen atom bridging the two iron cen-
tres, and even fewer involving a triazacyclononane
bridging ligand [3].
To broaden the scope of reactivity and different
binding modes of the tacn ligands, a series of ruthenium
complexes were synthesised. It was observed that the
reaction of (1-(2-methylpyridyl)-1,4,7-triazacyclonon-
ane) and RuCl2(PMePh2)4 in toluene at room temper-
ature gave no product and this is different to an
analogous reaction with RuCl2(PPh3)3 [19]. The reac-
tion proceeds at the reflux temperature of toluene and
the desired product 3 is formed according to Scheme 3.
Complex 3 was characterised by NMR spectroscopy,
mass spectrometry, microanalysis and X-ray crystal-
lography. This observation can be rationalised by the
increased coordination number of the ruthenium start-
ing material, which is six coordinate and therefore there
is no coordination site in which the ligand can initially
attach itself. In this case, it requires a higher reaction
temperature with which to labilise one of the phosphine
ligands.
Magnetic susceptibility measurements on compounds
1 and 2 have been recorded. Measurements were made
at 294.5 K. The observed leff for both compounds are
2.81 and 2.03 BM, respectively. The data show that both
compounds are antiferromagnetically coupled. The
values of leff are consistent with previously reported
examples [3]. Observed in the infrared spectrum for both
Scheme 1. Reagents and conditions, (i) O2/DCM.
Scheme 3. Reagents and conditions, (i) toluene/reflux 30 min/
RuCl2(PPh2Me), (ii) toluene/reflux 1 h/RuCl2(DMSO)4.
Scheme 2. Reagents and conditions, (i) THF, (ii) O2/FeCl2.

A.L. Gott et al. / Inorganica Chimica Acta 357 (2004) 689–698
691
This phenomenon is not reflected in the chemistry of
unfunctionalised tacn, where the reaction of tacn with
RuCl2(PMePh2)4, and RuCl2(PMe2Ph)4 both proceed at
room temperature to yield complexes [(tacn)RuCl(P-
MePh2)2]Cl (4) and [(tacn)RuCl(PMe2Ph)2]Cl (5), re-
spectively. But, it was observed that the formation of
complex 5 is less facile than 4, presumably due to the
stability of the starting material with respect to disso-
ciation of the phosphine ligands. Complexes 4 and 5
were both characterised by NMR spectroscopy, mass
spectrometry and elemental analysis. The attempted
formation of [(tacn)RuCl(PMe3)2]Cl proved impossible,
possibly due to the improved donor ability and dimin-
ished steric strain of the trimethylphosphine ligands,
which outweigh the stability associated with the mac-
rocyclic complex.
Complex 6 was synthesised according to a similar
method reported by Wieghardt [25]. As in the synthesis
Table 1
X-ray crystallographic data for compounds 1, 2, 3 and 6
1
2
3
6
Chemical formula
Formula weight
Crystal system
Space group
C24H44N8Cl4Fe2O3
746.17
monoclinic
C19H40N6Cl6Fe2O
692.97
triclinic
C53H74N8Cl10OP2Ru2
1457.78
triclinic
C15H28N4Cl4ORuS
562.34
monoclinic
ꢀ
ꢀ
P21=n
P1
P1
C2=c
ꢁ
a (A)
18.1197(3)
9.7776(2)
19.6919(5)
90
9.5812(4)
11.1007(3)
14.6649(9)
81.148(2)
75.641(2)
77.059(2)
1464.62(9)
2
10.3558(1)
15.7597(1)
20.7427(2)
110.9151(4)
100.1199(4)
93.4982(7)
3084.90(5)
2
25.7902(7)
9.4621(3)
21.4965(3)
90
ꢁ
b (A)
ꢁ
c (A)
a (°)
b (°)
c (°)
Volume (A )
Z
107.3660(10)
90
116.605(2)
90
3
ꢁ
3329.73(12)
4
150(2)
4690.30(2)
8
150(2)
Temperature (K)
Absorption coefficient
150(2)
1.562
150(2)
1.019
1.231
1.228
(mmꢁ1
)
Total data collected
Unique data
32672
14448
64679
11930
6518 [Rint ¼ 0:0881]
5580 [I > 2rðIÞ]
0.0497
5729 [Rint ¼ 0:0499]
5121 [I > 2rðIÞ]
0.0331
14,137 [Rint ¼ 0:0885]
12,232 [I > 2rðIÞ]
0.0382
4439 [Rint ¼ 0:0881]
3919 [I > 2rðIÞ]
0.0648
Observed data
R1½I > 2rðIÞꢂ
wR2½I > 2rðIÞꢂ
0.1367
0.0791
0.0984
0.1815
Fig. 1. (a) A view of 1 without hydrogen bonding with 50% probability ellipsoids and anions excluded, (b) a view of 1 with hydrogen bonding and the
chloride anions included.

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A.L. Gott et al. / Inorganica Chimica Acta 357 (2004) 689–698
of 3, stirring at room temperature did not yield the de-
sired complex. When the reaction was performed at
110 °C, a yellow solid was precipitated, as observed in
Scheme 3. The solid was isolated by filtration and ex-
tracted into dichloromethane. The dichloromethane
extracts were filtered from a thick black solid. The ex-
tracts were concentrated to a minimum volume,
whereupon addition of diethyl ether precipitated a yel-
low residue. The compound was characterised by NMR
spectroscopy, mass spectrometry and X-ray crystallog-
raphy. A satisfactory elemental analysis was not ob-
tained, this is thought to be due to residual
dimethylsulfoxide which could not be removed despite
repeated washing.
2.2. Crystallography
The crystallographic details for compounds 1, 2, 3
and 6 are given in Table 1. Complex 1 crystallised in the
space group P21=n. The molecular structure of 1 can be
seen in Fig. 1(a) and the relevant bond lengths are given
in Table 2. There is one molecule of the complex 1 per
asymmetric unit and four molecules per unit cell. Also
present in the asymmetric unit are two molecules of
water, one of which is found to be disordered. The
presence of the water is accounted for by the fact that
the compound was recrystallised from ÔwetÕ solvents.
The general structure is that of two distorted octahedra
linked by a bridging oxygen atom. The triazacyclonon-
ane ring occupies three of the co-ordination sites in a
facial manner and the pendant pyridine moiety, a
fourth. For the oxygen bridge to be incorporated into
the structure, however, one of the chloride ligands is
displaced. This displacement gives the complex an
overall 2+ charge, balanced by the two chloride counter
ions. From the molecular structure of 1 it can be seen
that the pendant pyridine rings appear to lie directly
above each other, in a parallel fashion. Analysis of the
structure reveals that the centroids of the two rings are
Table 2
Selected bond lengths and angles for complex 1
ꢁ
Bond
Length (A)
2.285(2)
2.193(2)
Fe(1)–N(1)
Fe(1)–N(2)
Fe(1)–N(3)
Fe(1)–Cl(1)
Fe(1)–Cl(2)
Fe(1)–O(1)
Fe(2)–N(4)
Fe(2)–N(5)
Fe(2)–N(6)
Fe(2)–Cl(3)
Fe(2)–Cl(4)
O(1)–Fe(2)
2.199(2)
2.4058(6)
2.3581(6)
1.7913(14)
2.277(2)
2.176(2)
2.240(2)
2.3834(6)
2.3580(6)
1.7839(14)
Angle (°)
76.92(7)
76.66(7)
78.02(6)
95.27(2)
156.89(9)
76.89(7)
77.21(7)
78.09(7)
97.99(2)
N(3)–Fe(1)–N(1)
N(2)–Fe(1)–N(3)
N(2)–Fe(1)–N(1)
Cl(2)–Fe(1)–Cl(1)
Fe(2)–O(1)–Fe(1)
N(6)–Fe(2)–N(4)
N(5)–Fe(2)–N(6)
N(5)–Fe(2)–N(4)
Cl(4)–Fe(2)–Cl(3)
ꢁ
3.862 A apart, further than the sum of the van der Waals
radii.
Three hydrogen bonds are apparent in the structure,
existing between the N–H units of the triazacyclononane
ring and the chloride anions, which is shown in Fig. 1(b)
and the data for the H-bond is given in Table 3. The
positions of these anions are the key to the overall ge-
ometry of the structure. Two chloride ions are present in
the structure, Cl(A) and Cl(B). Cl(A) is positioned be-
tween the two (tacn)Fe units. Two hydrogen bonds link
the chloride ion to the two triazacyclononane units,
Average bond lengths and angles
ꢁ
Average Fe–N (A)
ꢁ
2.29
2.38
Average Fe–Cl (A)
ꢁ
Average Fe–O (A)
1.79
77.30
96.63
Average N–Fe–N (°)
Average Cl–Fe–Cl (°)
Estimated standard deviations are given in parentheses.
Table 3
Selected bond lengths and angles for the H-bonding interactions for complexes 1, 2 and 3
ꢁ
D–H (A)
ꢁ
ꢁ
D–Hꢀ ꢀ ꢀA
Hꢀ ꢀ ꢀA (A)
Dꢀ ꢀ ꢀA (A)
Angle (°)
1
N2–H2ꢀ ꢀ ꢀCl3
N3–H3ꢀ ꢀ ꢀCl4
0.93
0.93
2.616
2.406
3.373
3.196
138.9
142.6
2
N4–H4ꢀ ꢀ ꢀCl2
N20–H20ꢀ ꢀ ꢀCl2
N23–H23ꢀ ꢀ ꢀCl1
0.93
0.93
0.93
2.295
2.323
2.495
3.209
3.219
3.320
167.3
161.7
147.8
3
N2–H2ꢀ ꢀ ꢀO1
O1–H2Wꢀ ꢀ ꢀCl12
N3–H3ꢀ ꢀ ꢀCl12
0.930
0.866
0.930
2.048
2.351
2.429
2.967
3.180
3.256
169.56
160.54
148.04

A.L. Gott et al. / Inorganica Chimica Acta 357 (2004) 689–698
693
ꢀ
N(4)–H(4)ꢀ ꢀ ꢀCl(A) and N(20)–H(20)ꢀ ꢀ ꢀCl(A) forming
an intramolecular bridge. It is probably this bridge
which holds the molecule in its distinctive arrangement,
rather than any interaction between the two pyridine
rings. A second, weaker type of hydrogen bond links the
other chloride anion to the cation, N(23)–H(23)ꢀ ꢀ ꢀCl(B)
(Fig. 4). Unfortunately, because the water molecules in
the structure are disordered and the hydrogen atoms
were not located, determination of any further hydrogen
bonding was not possible.
Complex 2 crystallised in the space group P1. The
molecular structure of 2 can be seen in Fig. 2(a) and the
relevant bond lengths are given in Table 4. There are
two molecules of the compound per unit cell and one
molecule of dichloromethane per molecule of complex.
The general structure is that of two slightly distorted
octahedra of LFeCl2 molecules linked by a bridging
oxygen atom which occupies the remaining co-ordina-
tion site of the metal centre. The average Fe–N bond for
ꢁ
the secondary amino groups is 2.202 A, whereas for the
Fig. 2. (a) A view of 2 without hydrogen bonding with 50% probability ellipsoids, (b) a representation of the intra- and intermolecular hydrogen
bonding in 2, (c) the intermolecular hydrogen bonding linking molecules of 2 in a chain and (d) a schematic representation of 2 (c).

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A.L. Gott et al. / Inorganica Chimica Acta 357 (2004) 689–698
Table 4
Selected bond lengths and angles for complex 2
The Fe(1)–O–Fe(2) angle is 156.89(9)° is comparable
to that found for [(tacn)Fe(acac)]2(l-O)(ClO4)2, where
Fe–O–Fe is 158.6(3)° [27]. Surprisingly, this angle is very
different from an analogous compound [(Me3tacn)-
FeCl2]2(l-O) [26], which has a Fe–O–Fe of 180°. A
possible explanation for this can be found when a
PLATON analysis [28] of 2 is carried out. This reveals the
existence of two hydrogen bonds in the lattice (Table 3)
and is shown in Fig. 2(b). Of the two bonds, one is a
weak intramolecular bond, N(2)–H(2)ꢀ ꢀ ꢀCl(3), forming
a bridge between the two tacn iron units. This could be
the reason for the Fe(1)–O–Fe(2) angle is 156.89(9)°. On
comparison with [(tacn)Fe(acac)]2(l-O)(ClO4)2 (exam-
ined on the CCDC database) with an Fe–O–Fe angle of
158.6(3)°, it is possible that there is H-bonding from the
tacn with the (ClO4)2, but it is difficult to determine due
to the disorder associated with the anion [27]. The other
ꢁ
Bond
Length (A)
2.199(3)
2.137(3)
2.256(3)
2.147(3)
2.3427(9)
1.797(2)
2.214(2)
2.151(2)
2.280(2)
2.183(2)
2.3157(8)
1.802(2)
Fe(1)–N(1)
Fe(1)–N(4)
Fe(1)–N(7)
Fe(1)–N(12)
Fe(1)–Cl(1)
Fe(1)–O(1)
Fe(2)–N(17)
Fe(2)–N(20)
Fe(2)–N(23)
Fe(2)–N(28)
Fe(2)–Cl(2)
O(1)–Fe(2)
Angle (°)
79.93(10)
77.72(12)
77.01(11)
76.06(9)
N(4)–Fe(1)–N(1)
N(4)–Fe(1)–N(7)
N(1)–Fe(1)–N(7)
N(12)–Fe(1)–N(1)
Fe(1)–O(1)–Fe(2)
N(20)–Fe(2)–N(17)
N(17)–Fe(2)–N(23)
N(20)–Fe(2)–N(23)
N(28)–Fe(2)–N(17)
173.23(13)
79.51(10)
76.89(9)
76.80(10)
75.84(10)
Average bond lengths and angles
ꢁ
Fe–N(tacn) (A)
ꢁ
Fe–N(py) (A)
2.206
2.165
77.98
2.3292
1.80
N–Fe–N(tacn) (°)
Fe–Cl (A)
ꢁ
ꢁ
Fe–O (A)
Estimated standard deviations in parentheses.
tertiary amino groups, the average Fe–N bond length is
ꢁ
2.282 A. These differ from [(Me3tacn)FeCl2]2(l-O) [26]
and [(tacn)Fe(acac)]2(l-O)(ClO4)2 [27], where the longer
Fe–N bonds trans to the oxygen atom, with values of
ꢁ
2.414(4) and 2.229(6) A, respectively.
Fig. 4. A view of 6 with 50% probability ellipsoids and anion excluded.
Fig. 3. (a) A view of 3 without hydrogen bonding with 50% probability ellipsoids, (b) a representation of the intra- and intermolecular hydrogen
bonding in 3.

A.L. Gott et al. / Inorganica Chimica Acta 357 (2004) 689–698
695
Table 5
Selected bond lengths and angles for complex 3
cavity between the tacn faces. Thus, there is a hydro-
philic interior to the chains of sandwiched 2 molecules
and the hydrophobic exterior of propene pendant arms
does not allow for hydrogen bonding between the
chains.
Single orange needles suitable for X-ray crystallo-
graphic analysis were grown by the diffusion of diethyl
ether vapour into a dichloromethane solution of 3 at
room temperature over a period of several days. Com-
Molecule 1
Molecule 2
ꢁ
Length (A)
Bond
Ru(1)–N(1)
Ru(1)–N(2)
Ru(1)–N(3)
Ru(1)–N(4)
Ru(1)–Cl(11)
Ru(1)–P(1)
P(1)–C(13)
Ru(2)–N(5)
Ru(2)–N(6)
Ru(2)–N(7)
Ru(2)–N(8)
Ru(2)–Cl(21)
Ru(2)–P(2)
P(2)–C(38)
2.089(2)
2.154(2)
2.117(2)
2.067(2)
2.4510(6)
2.3045(6)
1.835(3)
2.085(2)
2.138(2)
2.122(2)
2.056(2)
2.4568(6)
2.3016(6)
1.827(3)
ꢀ
plex 3 crystallised in the space group P1. There are four
molecules of 3, six molecules of dichloromethane and
two molecules of adventitious water in the unit cell;
therefore the asymmetric unit of 3 contains two mole-
cules of complex, three molecules of solvent and one
molecule of water. Selected bond lengths and angles can
be found in Table 4.
A change of a PPh3 group to a PPh2Me ligand has a
profound effect on the geometry of the resultant ruthe-
nium complex with respect to disposition of the ligands
with respect to each other, as well as Ru–N bond lengths.
Thus, the phosphine in 3 lies trans to the substituted ni-
trogen of the functionalised tacn whereas a chloride takes
this position for {chloro(triphenylphosphine)[j4-1-(2-
methylpyridyl)-1,4,7-triazacyclononane]ruthenium(II)}-
chloride [19]. All three ruthenium–nitrogen tacn skeleton
bond distances are markedly different for complex 3,
whereas for the PPh3 derivative they are of a very similar
Angle (°)
80.65(8)
80.59(8)
82.72(8)
81.50(8)
95.09(6)
96.31(6)
81.55(6)
81.18(8)
83.89(8)
80.60(8)
91.55(6)
96.21(6)
N(1)–Ru(1)–N(2)
N(2)–Ru(1)–N(3)
N(1)–Ru(1)–N(3)
N(1)–Ru(1)–N(4)
N(4)–Ru(1)–P(1)
N(4)–Ru(1)–Cl(11)
N(5)–Ru(2)–N(6)
N(6)–Ru(2)–N(7)
N(5)–Ru(2)–N(7)
N(5)–Ru(2)–N(8)
N(8)–Ru(2)–P(2)
N(8)–Ru(2)–Cl(21)
ꢁ
length with an average Ru–N bond distance of 2.12 A.
The Ru–N distance which is trans to the chloride ligand
Estimated standard deviations in parentheses.
ꢁ
has the shortest bond length (Ru(1)–N(1) ¼ 2.09 A),
H-bond is
a stronger intermolecular bond, N3–
presumably due to the trans influence of the chloride li-
gand. It is also notable the longest bond length of the
three is the one which lies trans to the phosphine ligands
H3ꢀ ꢀ ꢀCl4, forming a link from the N–H unit of a tacn
unit to the adjacent molecule. These hydrogen bonds
link the individual complexes into a chain. The com-
plexes in the chain are related to each other by trans-
lation (Figs. 2(c) and (d)). There are no hydrogen
bonding interactions between the chains, however, the
chains pack together in a specific manner. As the units
of the chain are linked together by translation, the
pendant arms are situated on the same face of the
molecule and the chains pack with these faces adjacent
to each other. The solvent molecules are found in the
ꢁ
(Ru(1)–N(2) ¼ 2.15 A).
The adventitious water molecule plays an important
role in the crystal packing of this particular structure. A
diagram illustrating this hydrogen bonding can be seen
in Fig. 3(b). The hydrogen bonded network involves
only one molecule of the asymmetric unit, along with the
associated counter-anion and water molecule. Through
ꢀ
the inversion symmetry associated with the P1 space
group, the symmetry equivalent molecule is generated
Table 6
Selected bond lengths and angles for complex 6
ꢁ
Length (A)
Bond
Vector
Angle (°)
Ru(1)–N(1)
Ru(1)–N(2)
Ru(1)–N(3)
Ru(1)–N(4)
Ru(1)–Cl(1)
Ru(1)–S(1)
S(1)–O(1)
2.071(4)
2.100(4)
2.130(4)
2.082(4)
2.4434(12)
2.2416(12)
1.494(4)
1.779(6)
1.787(5)
N(1)–Ru(1)–N(2)
N(2)–Ru(1)–N(3)
N(1)–Ru(1)–N(3)
N(1)–Ru(1)–N(4)
N(4)–Ru(1)–Cl(1)
N(2)–Ru(1)–S(1)
Cl(1)–Ru(1)–S(1)
83.63(18)
81.32(17)
81.49(17)
80.32(16)
96.799(12)
94.17(12)
90.16(15)
S(1)–C(13)
S(1)–C(14)
Estimated standard deviations in parentheses.

696
A.L. Gott et al. / Inorganica Chimica Acta 357 (2004) 689–698
and the hydrogen bonding is shown. The general
structural motif is that of a ÔdimericÕ complex.
The amine proton H2 hydrogen bonds to the oxygen
vents were degassed by three freeze–pump–thaw cycles
ꢁ
and stored over 4 A molecular sieves in a dry box, except
D2O. All reagents were purchased in reagent grade and
1
0
used without further purification. H, 13C{1H} and 31P
ꢁ
atom O1W with a bond length of 2.048 A (all hydrogen
bond lengths can be seen in Table 2). The proton asso-
ciated with this water molecule H2W0 is involved in a
hydrogen bond interaction with the chloride anion Cl12
NMR spectra were recorded on Bruker 250 and 500
MHz NMR spectrometers. IR spectra were recorded on
a Perkin–Elmer 1600 spectrometer. Mass spectrometry
was performed by the University of Leeds Mass Spec-
trometry Service. Elemental analyses were performed
by the University of Leeds Microanalytical Services.
1,4,7-triazacyclononane [34], 1-(2-methylpyridyl)-1,4,7-
triazacyclononane [20], and 1-(propene)-4,7-triazacy-
clononane [35], RuCl2(PPh2Me)4 [36], RuCl2(PPhMe2)4
[37], and RuCl2(DMSO)4 [33] were prepared by litera-
ture procedures.
ꢁ
with H–Cl distance determined as 2.351 A. The final
part of this network involves a further N–H–Cl inter-
action between Cl12 and the amine proton H30 of the
symmetry generated molecule 10 of the asymmetric unit.
A hydrogen bond is also observed between the second
counter-anion and the macrocyclic ring of the second
molecule of the asymmetric unit, N7–H7–Cl22. The
ꢁ
bond distance as determined by PLATON [28] is 2.609 A.
Single crystals of complex 6 were obtained as yellow
blocks from a dichloromethane/diethyl ether solution
which was stored at )20 °C for several months. The
complex crystallised in the monoclinic space group C2/c,
and there are therefore eight molecules of the complex in
the unit cell, along with eight molecules of dichlorome-
thane. The molecular structure can be seen in Fig. 4 and
selected bond lengths and angles can be seen in Tables 5
and 6. These values are typical of other complexes de-
termined in this area. There are many ruthenium DMSO
complexes which have been structurally characterised by
crystallography, and though many of these contain a
sulfur-bound dimethylsulfoxide ligand, there are few in
which can be directly compared with this donor ligand
set, that is ‘‘RuCl(DMSO)N4’’ [29–32].
4.1. [bis(1-(2-methylpyridyl)-1,4,7-triazacyclononane iron-
(III)chloride)l-oxo]Dichloride (1)
[1-(2-methylpyridyl)-1,4,7-triazacyclononane]Iron(II)-
dichloride (0.342 g, 0.0008 mol) was dissolved in di-
chloromethane (50 ml). The solution was stirred in air
overnight, during which time a brown solid was seen
to precipitate. The resulting suspension was then fil-
tered and the solid dried. (0.312 g, 0.00035 mol, 89%).
Recrystallisation from ethanol/diethyl ether afforded 1
as red plates. Found: C, 38.5; H, 6.0; N, 14.8; Cl, 19.2%.
Calc. for C24N8H40Fe2Cl4O.2H2O: C, 38.6; H, 5.9; N,
15.0; Cl, 19.0%.
4.2. Bis[1-(propene)-4,7-triazacyclononane iron(III)di-
chloride]oxide (2)
3. Conclusion
To a suspension of anhydrous iron(II)chloride (0.894
g, 0.0071 mol) in THF (50 ml) was added a solution of 1-
(propene)-4,7-triazacyclononane (1.312 g, 0.0078 mol)
in THF (20 ml). The resulting suspension was heated to
reflux for 7 days. After this time the THF was removed
under reduced pressure. The remaining solid was ex-
tracted with dichloromethane to give a dark green
powder. Recrystallisation from dichloromethane/petrol
afforded 2 as green crystals (1.22 g, 0.0019 mol, 56%).
Found: C, 33.0; H, 5.9; N, 12.1; Cl, 30.5%. Calc. for
C18H38N6Fe2Cl4O.CH2Cl2: C, 32.9; H, 5.8; N, 12.1; Cl,
30.7%.
The oxidation of functionalised (tacn)Fe(II) com-
plexes has been carried out in a controlled fashion to
lead to dramatically different types of l-oxo(tacn)Fe(III)
complexes, depending on the binding capability of the
pendant arm. The dimeric complexes produced show
interesting and different types of hydrogen bonding in-
teractions in the solid state. Also, a number of new
functionalised and unfunctionalised tacn Ru(II) com-
plexes have been synthesised and structural studies
carried out.
4. Experimental
4.3. [chloro(methyldiphenylphosphine){j4-1-(2-methyl-
pyridyl)-1,4,7-triazacyclononane}ruthenium(II)]chloride
(3)
Standard inert atmosphere techniques were used
throughout, where appropriate. Solvents were stored
over appropriate pre-drying agents and distilled under
N2. Dichloromethane was distilled from CaH2, THF
was distilled from potassium, toluene and petroleum
ether (b.p. 40–60 °C) were distilled from sodium and
diethyl ether was distilled from Na/Ph2CO. NMR sol-
To a Schlenk tube charged with a solution of
RuCl2(PMePh2)4 (0.250 g, 0.00026 mol) in toluene (10
ml) was added 1-(2-methylpyridyl)-1,4,7-triazacyclo-
nonane (0.085 g, 0.00039 mol). The resulting green so-

A.L. Gott et al. / Inorganica Chimica Acta 357 (2004) 689–698
697
lution was heated to reflux temperature for 1 h. After
this time, a yellow solid was observed to have precipi-
tated. The suspension was concentrated to ca. 5 ml, and
petrol added, resulting in further precipitation of a yel-
low solid. The solid was isolated by filtration, washed
with petrol, and dried in vacuo. Recrystallisation was
achieved by diffusion of diethyl ether vapour into a di-
chloromethane solution at room temperature. (0.131 g,
0.00022 mol, 84%). Found: C, 49.8; H, 5.5; N, 9.4%.
Calc. for C25H33N4Cl2PRu: C, 50.6; H, 5.6; N, 9.5%. 1H
NMR (300.13 MHz, CDCl3, 298 K): 1.82 (d, 3H,
4.5. [chloro(bis-dimethylphenylphosphine)-(1,4,7-triaza-
cyclononane)ruthenium(II)chloride] (5)
To a Schlenk tube charged with a solution of
RuCl2(PMe2Ph)4 (0.15 g, 0.00019 mol) in toluene (30
ml) was added 1,4,7-triazacyclononane (0.024 g, 0.00026
mol). The orange solution was stirred for 12 h and
darkened in colour with a yellow solid present. The
suspension was concentrated to ca. 5 ml, and petrol
added, resulting in further precipitation of a yellow so-
lid. The solid was isolated by filtration, washed with
petrol, and dried in vacuo. Recrystallisation was
achieved by diffusion of diethyl ether vapour into a di-
chloromethane solution at room temperature (0.030 g,
0.000053 mol, 27%). Found: C, 47.1; H, 6.5; N, 7.3%.
Calc. for C32H33N4Cl2PRu: C, 45.7; H, 6.5; N 7.3%. 1H
NMR (500.13 MHz, CDCl3, 298 K): 1.56 (s, br, 3H, N-
2
P(C6H5)2(CH3), J(1H–31P) ¼ 7.9 Hz), 1.95 (m, 1H, N–
CH2 ring), 2.57 (m, 1H, N-CH2 ring), 3.05 (m, 1H, N-
CH2 ring), 3.21 (d, 1H, N-CH2 arm, 2J(1H–1H) ¼ 15
Hz), 3.32–3.60 (m, 8H, N-CH2 ring), 3.86 (m, 1H, N-
CH2 ring), 4.40 (d, 1H, N-CH2 arm, 2J(1H–1H) ¼ 15
Hz), 4.45 (s, br, 1H, N-H), 5.20 (s, br, 1H, N-H), 7.17–
7.62 (m, complex, 13H, 10H of P(C6H5)2(CH3) and 3H,
CH of py, overlap) 9.02 (d, 1H, CH of py, 3J(1H–
1H) ¼ 4.8 Hz).
2
H), 1.64 (m, 6H, P(CH3)2(C6H5), J(1H–31P) ¼ 3.6 Hz),
2.07 (m, 6H, P(CH3)2(C6H5), 2J(1H–31P) ¼ 3.6 Hz), 2.19
(m, 2H, N-CH2 ring), 2.34 (m, 2H, N-CH2 ring), 2.43
(m, 2H, N-CH2 ring), 2.84 (m, 2H, N-CH2 ring), 3.51
(m, 3H, N-CH2 ring), 7.12 (m, 1H, P(CH3)2(C6H5)),
7.22 (m, 4H, P(CH3)2(C6H5)), 7.41 (m, 4H, P(CH3)2-
(C6H5)), 7.78 (m, 4H, P(CH3)2(C6H5)); 13C{1H} NMR
(62.90 MHz, CDCl3, 298 K): 17.4 (d, P(CH3)(C6H5)2,
1J(31P–13C) ¼ 26.4 Hz), 48.5, 49.5, 53.9 (3s, N-CH2
ring), 128.4, 128.8, 128.9, 129.5, 130.3, 132.1 (6s,
P(CH3)(C6H5)2, 31P{1H} NMR (101.26 MHz, CDCl3,
298 K): 23.6 (s, 2P(C6H5)3). MS (ES): 542.6 ([Mþ] ) Cl).
13C NMR (62.90 MHz, CDCl3, 298 K): 15.2 (d,
P(C6H5)2(CH3), 1J(31P–13C) ¼ 31.6 Hz), 45.5, 51.1, 53.1,
54.1, 60.8, 62.7 (6s, N-CH2 ring), 69.4 (N-CH2 arm),
122.3, 124.2 (2s, CH of py), 128.9, 129.1, 129.8, 129.9
(all s, P(C6H5)2(CH3)), 134.7, 153.2 (2s, CH of py),
165.3 (s, quaternary of py). 31P NMR: +34.7 (s,
P(C6H5)2(CH3)). MS (ES): 557.4 ([Mþ] ) Cl).
4.4. [chloro(methyldiphenylphosphine)-1,4,7-triazacyclo-
nonane]ruthenium(II)chloride (4)
4.6. Chloro(dimethylsulfoxide)[j4-1-(2-methylpyridyl)-
1,4,7-triazacyclononane]ruthenium(II)chloride (6)
To a Schlenk tube charged with a solution of
RuCl2(PMePh2)4 (0.25 g, 0.00026 mol) in toluene (30
ml) was added 1,4,7-triazacyclononane (0.033 g, 0.00026
mol). The resulting green solution changed colour im-
mediately to yellow. The suspension was concentrated to
ca. 5 ml, and petrol added, resulting in further precipi-
tation of a yellow solid. The solid was isolated by fil-
tration, washed with petrol, and dried in vacuo.
Recrystallisation was achieved by diffusion of diethyl
ether vapour into a dichloromethane solution at room
temperature (0.075 g, 0.00017 mol, 41%). Found: C,
55.3; H, 6.0; N, 5.7%. Calc. for C32H33N4Cl2PRu: C,
To a Schlenk tube charged with a suspension of
RuCl2(DMSO)4 (2.50 g, 0.0052 mol) in toluene (50 ml)
was added 1-(2-methylpyridyl)-1,4,7-triazacyclononane
(1.19 g, 0.0054 mol). The suspension was heated to re-
flux temperature for 1 h. After this time, the resulting
yellow solid was isolated by filtration and extracted into
dichloromethane (50 ml). The dichloromethane extracts
were concentrated to ca. 5 ml, and diethyl ether added,
resulting in the precipitation of a bright yellow solid
which was washed with diethyl ether (6 ꢃ 20 ml) and
dried in vacuo. Single crystals suitable for X-ray crys-
tallographic analysis were grown from a dichlorome-
thane/diethyl ether solution (1.744 g 0.0037 mol, 71 %).
Found: C, 32.1; H, 5.7; N, 9.5%. Calc.for C14H26-
N4Cl2ORuS: C, 35.3; H, 5.6; N, 9.6%. 1H NMR
((CD3)2SO, 250.13 MHz, 298 K) 2.57–3.25 (m, 12H, N-
CH2 ring), 3.31–3.40 (s, 6H, (CH3)2S(@O)-Ru), 4.59 (d
of d, 2H, N-CH2 arm, 2J(1H–1H) ¼ 14.9 Hz), 6.02 (s, br,
1H N-H), 6.89 (s, br, 1H, N-H), 7.50 (m, 2H, CH of py),
7.90 (t, 1H, CH of py, 3J(1H–1H) ¼ 6.3 Hz), 8.79 (d, 1H,
1
54.8; H, 5.9; N, 6.0%. H NMR (300.13 MHz, CDCl3,
298 K): 1.54 (s, br, 3H, N-H), 1.82 (m, 6H,
P(C6H5)2(CH3), 2.22 (m, 3H, N-CH2 ring), 2.51 (m, 3H,
N-CH2 ring), 3.25 (m, 2H, N-CH2 ring), 3.67 (m, 2H, N-
CH2 ring), 3.90 (m, 2H, N-CH2 ring), 7.17 (m, 8H,
P(C6H5)2(CH3)), 7.45 (m, 4H, P(C6H5)2(CH3)), 7.55 (m,
4H, P(C6H5)2(CH3)), 7.86 (m, 4H, P(C6H5)2(CH3));
13C{1H} NMR (62.90 MHz, CDCl3, 298 K): 13.4 (d,
P(C6H5)2(CH3)), 1J(31P–13C) ¼ 26.4 Hz), 48.6, 49.4, 53.5
(3s, N-CH2 ring), 69.4 (N-CH2 arm), 128.4, 128.8, 128.9,
129.5, 130.3, 132.1 (all s, P(C6H5)2(CH3)); 31P{1H}
NMR (101.26 MHz, CDCl3, 298 K): 27.3 (s,
2P(C6H5)3). MS (ES): 666.8 ([Mþ] ) Cl).
3
CH f py, J(1H–1H) ¼ 5.0 Hz). 13C{1H} NMR (62.90
MHz, (CD3)2SO, 298 K): 52.0, 53.0, 54.1, 55.5, 59.2,
61.8 (6s, N-CH2 ring), 69.3 (s, N-CH2 arm), 122.5,

698
A.L. Gott et al. / Inorganica Chimica Acta 357 (2004) 689–698
[12] T. Justel, J. Bendix, N. Metzler-Nolte, T. Weyhermuller, B.
Nuber, K. Wieghardt, Inorg. Chem. 37 (1998) 35.
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Angew. Chem. Int. Ed. Engl. 26 (1987) 250.
124.5, 136.4, 147.3 (4s, CH of py), 165.8 (s, quaternary
of py) 47.6, 48.2 (2s, CH3)2S(@O)-Ru DMSO) MS (ES):
434.8 ([Mþ] ) Cl), 356.9 ([Mþ] ) Cl ) DMSO).
[14] S.M. Yang, W.C. Cheng, K.K. Cheung, C.M. Che, S.M. Peng, J.
Chem. Soc., Dalton Trans. (1995) 227.
4.7. Crystallographic data collection and structure col-
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[15] S.M. Yang, M.C.W. Chan, S.M. Peng, C.M. Che, Organometal-
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Data for compounds 1, 2, 3 and 6 were collected on
a Nonius KappaCCD area-detector diffractometer us-
ing graphite monochromated Mo Ka radiation (k ¼
[17] S.M. Au, S.B. Zhang, W.H. Fung, W.Y. Yu, C.M. Che, K.K.
Cheung, Chem. Commun. (1998) 2677.
ꢁ
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311.
0:71073 A) using 1.0° /-rotation frames. Pertinent crys-
tallographic details are given in Table 2.
[19] A.L. Gott, P.C. McGowan, T.J. Podesta, M. Thornton-Pett, J.
Chem. Soc., Dalton Trans. (2002) 3619.
The structures of all compounds were solved by direct
methods using SHELXS 86. Refinement, by full-matrix
least squares on F 2 using SHELXS 97, was similar for all
four compounds. Hydrogen atoms were constrained to
idealised positions using a riding model (with free ro-
tation for methyl groups), with the exception of the
hydrogen atoms of the water molecules in 3 which were
located in the difference map and refined isotropically.
The hydrogen atoms of the disordered water molecules
of 1 were not located. All non-hydrogen atoms were
refined anisotropically.
[20] P.C. McGowan, T.J. Podesta, M. Thornton-Pett, Inorg. Chem. 40
(2001) 1445.
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Acknowledgements
[26] A.C. Moreland, T.B. Rauchfuss, Inorg. Chem. 39 (2000)
3029.
We thank Dr. Mark Thornton-Pett with help the
X-ray crystallography.
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