L2. EIMS: m/z 282 (80%, M`), 182 (100%). 1H NMR: d 9.00 (2H,
dd, J 4.3, 1.6; phen H2/H9), 8.44 (2H, dd, J 8.2, 1.6; phen H4/H7), 7.55
would maximise the likelihood of seeing a perturbation of the
properties of the [Ru(bipy) ]2` core.
3
(2H, dd, J 8.2, 4.3 Hz; phen H3/H8), 4.52 (4H, m; CH ), 3.98 (4H, m;
[
Ru(bipy) (L5)][PF ] shows the typical redox properties
2
2
6 2
CH ).
of a [Ru(bipy) ]2` derivative, with a Ru(II)/Ru(III) couple at
0.89 V vs. ferrocene/ferrocenium (Fc/Fc`), and three ligand-
2
L3. EIMS: m/z 326 (60%, M`), 182 (100%). 1H NMR: d 9.12 (2H,
3
[
dd, J 4.3, 1.6; phen H2/H9), 8.54 (2H, dd, J 8.2, 1.6; phen H4/H7), 7.64
centred couples at [1.74, [1.93 and [2.17 V vs. Fc/Fc` in
MeCN (the other complexes show essentially identical
behaviour). On addition of Ba2` to the solution, the ligand-
centred reductions become rather broad and ill-deÐned, but
the Ru(II)/Ru(III) couple undergoes a gradual positive shift to
(2H, dd, J 8.2, 4.3 Hz; phen H3/H8), 4.44 (4H, m; CH ), 4.05 (4H, m;
2
CH ), 3.90 (4H, s; CH ).
2
2
L4. EIMS: m/z 370 (40%, M`), 182 (100%). 1H NMR: d 9.12 (2H,
dd, J 4.3, 1.6; phen H2/H9), 8.56 (2H, dd, J 8.2, 1.6; phen H4/H7), 7.62
(
2H, dd, J 8.2, 4.3 Hz; phen H3/H8), 4.46 (4H, m; CH ), 4.10 (4H, m;
2
CH ), 3.81 (8H, m; CH ).
2
2
]
0.94 V after addition of ca. 10 equivalents of Ba2`, a shift of
L5. EIMS: m/z 414 (70%, M`), 182 (100%). 1H NMR: d 9.11 (2H,
5
0 mV. Clearly, binding of Ba2` at the 18-crown-6 site causes
dd, J 4.3, 1.6; phen H2/H9), 8.59 (2H, dd, J 8.2, 1.6; phen H4/H7), 7.63
(
2H, dd, J 8.2, 4.3 Hz; phen H3/H8), 4.45 (4H, m; CH ), 4.04 (4H, m;
a slight electrostatic destabilisation of the Ru(III) state. The
e†ect is rather modest, but is in the same range observed by
Beer and co-workers.2,14 and Yam and co-workers.4,5 for
related redox-responsive systems based on attachment of
group 1A or IIA metal ions to pendant crown ethers. More
detailed studies on this e†ect are in progress.
2
CH ), 3.82 (8H, m; CH ), 3.72 (4H, s; CH ).
2
2
2
”
The following synthesis of [Ru(bipy) (L5)][PF ] is typical. To a
6 2
solution of L5 (0.035 g, 0.094 mmol) in EtOH (25 cm3) was added
2
[
Ru(bipy) Cl ] É 2H O (0.050 g, 0.096 mmol) and the reaction mixture
2
2
2
heated to reÑux for 2 h. After this time the reaction mixture was
cooled and the solvent evaporated in vacuo. The pure complex was
obtained
by
column
chromatography
on
silica,
using
We also attempted to investigate the e†ects of secondary
metal-ion binding on the optical spectroscopic properties of
the complexes; however this was less successful. Addition of
MeCNÈH OÈsaturated aqueous KNO (10 : 2 : 1, v/v) as eluent; the
2
3
major orange band was collected, concentrated in vacuo, and the
complex precipitated by addition of aqueous NH PF . After Ðltration
Ba2` (up to
5
equivalents) to
a
sample of
4
6
and drying, the complex was recrystallised from MeCNÈEt O to give
2
[
Ru(bipy) (L5)][PF ] resulted in no signiÐcant change of
[Ru(bipy) (L5)][PF ] in 40% yield.
2
6 2
2
6 2
either the 1MLCT absorption maximum at 451 nm, or of the
Complexes with the other ligands L1ÈL4 were prepared in a similar
manner in yields of typically 40È55%. Electrospray mass spectra in
MeCN showed, in every case, a strong peak corresponding to the
3
MLCT emission at 610 nm.
In conclusion, we have described a simple synthesis of a
[
\
Ru(bipy) (Ln)]2` dication, as follows: n \ 1, m/z \ 326; n \ 2, m/z
homologous series of new ligands in which a crown ether
macrocycle is attached to an externally-directed phenanthrol-
ine fragment. Such ditopic ligands have clear promise for the
preparation of heterodinuclear complexes in which there are
electronic interactions between the two metal centres. One
such complex, [Ru(bipy) (L5)][PF ] , shows a small but sig-
2
349; n \ 3, m/z \ 370; n \ 4, m/z \ 391.5; n \ 5, m/z \ 416. Satis-
factory elemental analyses were obtained for all of the complexes.
° Di†raction intensity data were collected on a Siemens SMART-
CCD di†ractometer. The software used was SHELXS-97 for structure
solution,15 SHELXL-97 for structure reÐnement,15 and SADABS for
the absorption correction.16 Details of the crystal parameters, data
collection and reÐnement are collected in Table 1. Structure solution
and reÐnement was generally straightforward, apart from problems
associated with disordered solvent molecules/anions, which will be
discussed in more detail in a subsequent full paper. CCDC reference
number 440/241. See htlp: www.rsc.org/suppdata/nj/b0/b008378j/ for
crystallographic Ðles in .cif format.
2
6 2
niÐcant change in its redox behaviour in the presence of Ba2`.
Studies extending the use of these ligands to other redox-
active or luminescent complexes are in progress.
1
2
3
F. C. J. M. van Veggel, W. Verboom and D. N. Reinhoudt, Chem.
Rev., 1994, 94, 279.
Acknowledgements
P. D. Beer, O. Kocian, R. J. Mortimer and C. Ridgway, J. Chem.
Soc., Faraday T rans., 1993, 89, 333.
We thank the Leverhulme foundation and the EPSRC (UK)
for Ðnancial support. M. D. W. is the Royal Society of Chem-
istry Sir Edward Frankland fellow for 2000/2001.
S. Encinas, K. L. Bushell, S. M. Couchman, J. C. Je†ery, M. D.
Ward, L. Flamigni and F. Barigelletti, J. Chem. Soc., Dalton
T rans., 2000, 1783.
4
5
6
7
V. W.-W. Yam, V. W.-M. Lee, F. Ke and K. W.-M. Siu, Inorg.
Chem., 1997, 36, 2124.
V. W.-W. Yam and V. W.-M. Lee, J. Chem. Soc., Dalton T rans.,
1997, 3005.
Notes and references
S. Belanger, M. Gilbertson, D. I. Yoon, C. I. Stern, X. Dang and
J. T. Hupp, J. Chem. Soc., Dalton T rans., 1999, 3407.
M. Schmittel and H. Ammon, J. Chem. Soc., Chem. Commun.,
1995, 687.
W. Paw and R. Eisenberg, Inorg. Chem., 1997, 36, 2287.
L. F. Lindoy, T he Chemistry of Macrocyclic L igand Complexes,
Cambridge University Press, Cambridge, 1989, ch. 4.
¤
The following synthesis of L5 is typical. To a stirred solution of 5,6-
dihydroxy-1,10-phenanthroline (0.26 g, 1.24 mmol) in dry DMF (8
cm3) under N was added NaH (0.10 g of 60% mineral oil dispersion,
8
9
2
2
.5 mmol) and the mixture was stirred for 5 min. Then, a solution of
pentaethyleneglycol-ditosylate (0.67 g, 1.22 mmol) in degassed DMF
(
7 cm3) was added and the mixture was stirred at 80 ¡C for 18 h. The
10 R. Boulatov, B. Du, E. A. Meyers and S. G. Shore, Inorg. Chem.,
solvent was then removed in vacuo, water (25 cm3) was added, and the
1999, 38, 4554.
suspension was extracted with several small portions of CH Cl
11 M. P. Murchie, J. W. Bovenkamp and A. Rodrigue, Can. J.
Chem., 1988, 66, 2515.
2
2
which were combined and dried over MgSO , before evaporation to
4
dryness in vacuo to give a brown oil. Chromatography on silica with
12 K. A. Watson, S. Fortier, M. P. Murchie and J. W. Bovenkamp,
Can. J. Chem., 1991, 69, 687.
CH Cl ÈMeOH (90 : 10, v/v) a†orded pure L5 as a yellow oil in 50%
2
2
yield.
13 S. Chadwick, U. Englich and K. Ruhlandt-Senge,
Organometallics, 1997, 16, 5792.
The other ligands L1ÈL4 were prepared in exactly the same way,
but using the ditosylate of mono-, di-, tri- or tetra-ethylene glycol (1
equiv. with respect to 5,6-dihydroxy-1,10-phenanthroline), respec-
tively. Yields were in the range 40È60% in every case. SigniÐcant
characterisation data are summarised below. All NMR spectra were
14 P. D. Beer, H. Sikanyika, C. Blackburn, J. F. McAleer and M. G.
B. Drew, J. Chem. Soc., Dalton T rans., 1990, 3295.
15 G. M. Sheldrick, SHELXS-97 and SHELXL-97, programs for
crystal structure solution and reÐnement, University of
recorded in CDCl . L1. EIMS: m/z 238 (95%, M`), 182 (100%). 1H
Gottingen, Germany, 1997.
3
NMR: d 9.07 (2H, dd, J 4.3, 1.6; phen H2/H9), 8.44 (2H, dd, J 8.2, 1.6;
16 G. M. Sheldrick, SADABS, a program for absorption correction
with the Siemens SMART area-detector system, University of
phen H4/H7), 7.60 (2H, dd, J 8.2, 4.3 Hz; phen H3/H8), 4.54 (4H, s;
CH ).
Gottingen, Germany, 1996.
2
New J. Chem., 2001, 25, 185È187
187