Syntheses and structures of mononuclear {Re(CO)3Cl(NN)} 'complex ligands' with a pendant imino-pyridine binding site, and preparation of some heterodinuclear Re(I)-lanthanide(III) complexes

Article abstract of DOI:10.1016/S0020-1693(03)00202-0

A series of potentially dinucleating ligands, each with two bidentate imino-pyridine compartments, has been used to prepare the mononuclear complexes [Re(CO)₃Cl(Lⁿ)] (n=1-4) which each have a vacant binding site and so constitute 'complex ligands' for the stepwise synthesis of heterodinuclear complexes. Three of the complexes (with L¹, L² and L⁴) have been structurally characterised. The mononuclear complex [Re(CO)₃Cl(L⁵)], arising from decomposition of [Re(CO)₃Cl(L³)] by hydrolysis of the non-coordinated imine unit, was also isolated and structurally characterised. Luminescence studies show that these compounds are only very weak emitters. The 'complex ligand' [Re(CO)₃Cl(L¹)] has been reacted with [Ln(hfac)₃]·2H₂O (Ln=Yb, Er) to prepare the heterodinuclear complexes [Re(CO)₃Cl(μ-L¹)Ln(hfac)₃] in which the {Ln(hfac)}₃ unit is attached to the second bidentate imino-pyridine site of [Re(CO)₃Cl(L¹)]. The crystal structures of these show that the bridging ligand has to twist to accommodate the two bulky metal fragments, and that the lanthanide units have an 8-coordinate square-antiprismatic geometry.

Full text of DOI:10.1016/S0020-1693(03)00202-0

Inorganica Chimica Acta 351 (2003) 159ꢀ166
/
www.elsevier.com/locate/ica
Syntheses and structures of mononuclear {Re(CO)3Cl(NN)}
‘complex ligands’ with a pendant iminoꢀpyridine binding site, and
preparation of some heterodinuclear Re(I)ꢀlanthanide(III) complexes
/
/
Nail M. Shavaleev a, Zoe R. Bell a, Gianluca Accorsi b, Michael D. Ward a,*
¨
a School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, UK
b Istituto per la Sintesi Organica e Fotoreattivita` (ISOF-CNR), Via P. Gobetti 101, I-40129 Bologna, Italy
Received 19 November 2002; accepted 19 February 2003
Abstract
A series of potentially dinucleating ligands, each with two bidentate iminoꢀ
/
pyridine compartments, has been used to prepare the
mononuclear complexes [Re(CO)3Cl(Ln)] (nꢁ
/
1ꢀ
/
4) which each have a vacant binding site and so constitute ‘complex ligands’ for the
stepwise synthesis of heterodinuclear complexes. Three of the complexes (with L1, L2 and L4) have been structurally characterised.
The mononuclear complex [Re(CO)3Cl(L5)], arising from decomposition of [Re(CO)3Cl(L3)] by hydrolysis of the non-coordinated
imine unit, was also isolated and structurally characterised. Luminescence studies show that these compounds are only very weak
emitters. The ‘complex ligand’ [Re(CO)3Cl(L1)] has been reacted with [Ln(hfac)3]×
/
2H2O (Lnꢁ
/
Yb, Er) to prepare the heterodi-
pyridine site
nuclear complexes [Re(CO)3Cl(m-L1)Ln(hfac)3] in which the {Ln(hfac)}3 unit is attached to the second bidentate iminoꢀ
/
of [Re(CO)3Cl(L1)]. The crystal structures of these show that the bridging ligand has to twist to accommodate the two bulky metal
fragments, and that the lanthanide units have an 8-coordinate square-antiprismatic geometry.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Re(I)ꢀ
/
lanthanide(III) complexes; Iminoꢀ/pyridine binding site; Square-antiprismatic geometry; Crystal structures; Luminesence
1. Introduction
has metal units added to its binding domains in a
stepwise fashion [1,2]. This requires isolation of ‘com-
There has been extensive recent interest in the
synthesis and photophysical characterisation of hetero-
polynuclear complexes in which photoinduced energy-
transfer occurs between the components [1,2]. Such
studies are facilitated by the presence of two luminescent
units in the complex since the extent of intramolecular
energy transfer can be monitored either by luminescence
quenching at the donor chromophore or/and by the
amount of sensitised emission from the acceptor chro-
mophore.
plex ligands’ at the intermediate stages in which metal
complexes are prepared which have residual vacant
coordination sites for use as ligands in subsequent
complexation steps. An extremely wide variety of
bridging ligands has been used for this purpose, usually
based on bidentate or terdentate polypyridyl (or similar)
terminal binding sites to provide the required MLCT
excited states of the metal fragments [1].
In this paper, we report the syntheses, characterisa-
tion, crystal structures and luminescence properties of a
series of mononuclear Re(I) complexes based on the
The syntheses of such heteropolynuclear complexes,
involving metal complex fragments which are usually
kinetically inert, is generally based on a ‘complexes as
ligands’ approach in which a polytopic bridging ligand
potentially bridging ligands L1ꢀ
contain two pyridylꢀimine binding sites; bidentate
pyridylꢀimine ligands have been examined by others
/
L4 (Chart 1), which all
/
/
as a synthetically convenient alternative to substituted
bipyridines for the study of the photophysical properties
of {Re(CO)3Cl(NN)} chromophores [3]. To illustrate
* Corresponding author. Tel.: ꢂ
0509.
E-mail address: mike.ward@bristol.ac.uk (M.D. Ward).
/
44-117-928 7655; fax: ꢂ44-117-929
/
how
the
mononuclear
‘complex
ligands’
0020-1693/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0020-1693(03)00202-0

160
N.M. Shavaleev et al. / Inorganica Chimica Acta 351 (2003) 159ꢀ166
/
L3 was formed in much higher yield than L4 and was
noticeably more stable. The mononuclear complexes
[Re(CO)3Cl(Ln)] (nꢁ
/
1ꢀ4) were prepared by reaction of
/
the appropriate ligand with [Re(CO)5Cl] in a non-polar
solvent (typically hexane or toluene) under N2, and
usually precipitated in analytically pure form during the
reaction. The choice of solvent for the synthesis of these
complexes was based on the solubility of the ligands.
Whenever possible hexane was used because the mono-
nuclear complex precipitates pure from the reaction;
reaction in toluene in contrast requires a large excess of
ligands and careful control of temperature to prevent
further reaction to the dinuclear complex. The complex
[Re(CO)3Cl(L5)] resulted from an attempt to purify
[Re(CO)3Cl(L3)] by column chromatography; clearly,
the non-coordinated imine unit hydrolysed during this
process. All five complexes were satisfactorily charac-
terised by elemental analysis and fast atom bombard-
ment mass spectrometry (FAB MS). All complexes are
well soluble in THF and chlorinated solvents (although
we note that CHCl3 leads to slight decomposition), and
insoluble in ether and hexane. The complexes with the
methyl-substituted ligands are more readily soluble.
In addition, crystal structures have been obtained for
the complexes with L1, L2, L3 and L5 (see Figs. 1ꢀ
4,
/
Chart 1.
respectively, and Tables 1 and 2). In all four mono-
nuclear complexes, the Re(I) centres have the usual
pseudo-octahedral fac-(CO)3N2Cl coordination geome-
[Re(CO)3Cl(Ln)] (nꢁ
for preparation of dinuclear complexes, the complexes
[Re(CO)3Cl(m-L1)Ln(hfac)3] (Lnꢁ
Yb, Er; Hhfacꢁhex-
/
1ꢀ
/
4) can be used as components
try with unremarkable metalꢀ
/
ligand distances (Table 2).
/
/
In [Re(CO)3Cl(L1)], the ligand is slightly twisted, such
that the mean planes of the coordinated and pendant
pyridyl rings have an angle of 25.58 between them. In
[Re(CO)3Cl(L2)], the steric effect of the methyl groups
results in a much larger distortion from planarity, with
65.58 between the mean planes of the free and coordi-
nated pyridyl rings, and a torsion angle of 89.18 about
afluoroacetylacetone) have been prepared and structu-
rally characterised, in which the d-block Re(I)
chromophore [3,4] and the potentially near-IR lumines-
cent f-block chromophore [5] are connected by the
bis(pyridylꢀ
imine) bridging ligand L1. A mononuclear
/
complex of L5, arising from hydrolytic decomposition of
[Re(CO)3Cl(L3)], is also described.
the N(21)ꢀ/N(22) bond which makes the two methyl
Of these ligands, L1 and L2, in which the two pyridylꢀ
/
groups essentially perpendicular to one another. In
[Re(CO)3Cl(L4)], the ligand is also twisted, with the
mean plane of the central phenyl ring being at an angle
of 79.78 to that of the coordinated pyridyl ring and 40.68
imine units are directly linked by means of a diazine
bridge, have also been of interest because of their ability
to form helicates with labile transition-metal ions, which
depends on their capacity to twist about the flexible
central Nꢀ
/
N linkage [6]. A variety of related dinucleat-
imine binding sites sepa-
ing ligands with two pyridylꢀ
/
rated by aromatic spacers have recently been
investigated by Hannon et al. for similar reasons [7].
2. Results and discussion
2.1. Mononuclear Re complexes
The ligands L1 and L2 were first prepared and studied
by Stratton et al. [6b,6c,6d,6e]. Ligands L3 and L4 were
simply prepared by condensation of 2-formylpyridine or
2-acetylpyridine, respectively with p-phenylenediamine;
Fig. 1. Molecular structure of [Re(CO)3Cl(L1)].

N.M. Shavaleev et al. / Inorganica Chimica Acta 351 (2003) 159ꢀ
/166
161
process, characteristic of the {Re(CO)3Cl(diimine)}
chromophore (Fig. 5) [3,4]. For the complexes with L1
and L2, these are clearly defined maxima, with the
transition in [Re(CO)3Cl(L1)] being at considerably
lower energy than the analogous transition in
[Re(CO)3Cl(L2)]; we ascribe this to the fact that L1 has
a more nearly planar geometry (see crystal structures
above), so the acceptor p* orbital is more extensively
delocalised and hence lower in energy than that for L2.
For the complexes with L3 and L4, the MLCT transition
is less clearly defined due to an adjacent and more
intense ligand-centred transition, but the same pattern is
evident with the more substituted (and hence twisted)
ligand L4 resulting in a higher-energy MLCT transition.
Examination of the luminescence properties in CH2Cl2
at room temperature showed that in all cases the
Fig. 2. Molecular structure of [Re(CO)3Cl(L2)].
emission is very weak (f B
the emission maximum is at approximately 650 nm, with
t B
6 ns; for [Re(CO)3Cl(L3)] the emission maximum is
/
10ꢃ4). For [Re(CO)3Cl(L2)]
/
at approximately 730 nm with t B10 ns. For the other
/
two complexes (with L1 and L4), the luminescence is so
weak that no quantification of the parameters is
possible.
2.2. Dinuclear ReꢀLn complexes
/
Fig. 3. Molecular structure of [Re(CO)3Cl(L4)].
To exemplify the use of these mononuclear ‘complex
ligands’ for the syntheses of dinuclear complexes, the
heterodinuclear complexes [Re(CO)3Cl(m-L1)Ln(hfac)3]
(Lnꢁ
/
Er, Yb) were prepared by reaction of
[Re(CO)3Cl(m-L1)] with the appropriate [Ln(hfac)3]×
/
2H2O in a mixture of benzene and heptane. Simply
mixing the two components in a 1:1 ratio, followed by
slow evaporation over a period of several days, give high
yields of the heterodinuclear ReꢀLn adducts. This
/
preparation exploits the fact that neutral 6-coordinate
complexes of the type [Ln(dik)3] (where ‘dik’ is a
chelating 1,3-diketonate monoanion) form 8-coordinate
adducts [Ln(dik)3(NN)] with bidentate N-donor diimine
ligands [8]. Coordination of the electropositive lantha-
nide fragment to the second coordination site results in a
red-shift of the Re-based MLCT transition from 437 nm
Fig. 4. Molecular structure of [Re(CO)3Cl(L5)].
to that of the pendant pyridyl ring. In [Re(CO)3Cl(L5)],
the mean plane of the pendant phenyl ring is at an angle
of 53.98 with respect to the coordinated pyridyl ring. In
all of [Re(CO)3Cl(Ln)] (nꢁ
1, 2, 4) the arrangement of
/
pyridyl and imino N-donors at the pendant coordina-
tion site is approximately transoid to prevent unfavour-
able electronic interactions between the two lone pairs.
The electronic spectra of [Re(CO)3Cl(Ln)] (nꢁ
/
1ꢀ
450 nm range which
iminoꢀpyridine MLCT
/
4)
Fig. 5. Electronic spectra of mononuclear complexes [Re(CO)3Cl(Ln )]
all show a transition in the 400ꢀ
/
may be assigned as a Re0
/
/
(nꢁ
/
1, *
/
*/
; nꢁ
/
2, ꢀ
/
ꢀ/
ꢀ/
ꢀ/
; nꢁ
/
3, ꢀ
/
ꢁ
/
ꢀ/
ꢁ
/
ꢀ/
ꢁ
/
ꢀ/
; nꢁ
/
4, ꢁ
/
ꢁ
/
ꢁ
/
ꢁ ꢁ).
/
/

162
N.M. Shavaleev et al. / Inorganica Chimica Acta 351 (2003) 159ꢀ166
/
Table 1
Crystallographic data a
Compound
[Re(CO)3Cl(L1)] [Re(CO)3Cl(L2)] [Re(CO)3Cl(L4)] [Re(CO)3Cl(L5)] [Re(CO)3Cl(L1)Yb(hfac)3] [Re(CO)3Cl(L1)Er(hfac)3]
Empirical for-
mula
C
15H10ClN4O3Re C17H14ClN4O3Re C23H18ClN4O3Re C15H11ClN3O3Re C30H13ClF18N4O9ReYb
C30H13ClErF18N4O9Re
1304.35
Formula
weight
Crystal system triclinic
515.9
543.97
620.06
502.92
1310.13
monoclinic
monoclinic
monoclinic
monoclinic
monoclinic
¯
P1
Space group
Unit cell di-
mensions
/
C2/c
P2(1)/c
P2(1)/n
P2(1)/n
P2(1)/n
˚
a (A)
6.9851(12)
9.0303(19)
13.1710(15)
81.313(19)
84.537(15)
72.379(13)
781.6(2)
2
34.369(5)
6.4829(12)
17.195(3)
90
11.9811(12)
15.035(2)
13.6591(17)
90
12.8895(13)
8.9099(11)
13.907(3)
90
11.6833(13)
29.425(5)
12.0644(14)
90
11.684(2)
29.423(6)
12.034(3)
90
˚
b (A)
˚
c (A)
a (8)
b (8)
111.191(9)
90
114.990(9)
90
99.593(12)
90
104.981(10)
90
104.86(2)
90
g (8)
3
V (A )
˚
3572.3(10)
8
2.023
2230.2(5)
4
1.847
1574.8(4)
4
2.121
4006.5(9)
4
2.172
3998.6(15)
4
2.167
Z
Dcalc (Mg
)
2.192
mꢃ3
Data/re-
3566/0/217
4098/0/237
5100/34/286
3627/0/208
9136/0/577
9161/0/577
straints/para-
meters
m (mmꢃ1
)
7.966
6.978
5.601
7.903
5.544
5.315
R1 [I ꢀ
wR2
/2s(I)], 0.0315, 0.0717
0.0261, 0.0574
0.0309, 0.0695
0.0258, 0.0563
0.0349, 0.0813
0.0331, 0.0688
a
a
The value of R1 is based on selected data with I ꢀ2s(I); the value of wR2 is based on all data.
/
in mononuclear [Re(CO)3Cl(L1)] to 457 nm in dinuclear
is increased to 38.38 (Mꢁ
lanthanide ion in each case is 8-coordinate with an
approximately square-antiprismatic coordination geo-
/
Yb) or 38.58 (MꢁEr). The
/
[Re(CO)3Cl(m-L1)Ln(hfac)3].
The crystal structures of the complexes with LnꢁYb
/
metry; for Mꢁ
are formed from O(51)/O(55)/N(31)/N(22) and O(41)/
O(45)/O(61)/O(65); for MꢁEr the two planes are
formed from O(51)/O(55)/O(61)/O(65) and N(22)/
N(31)/O(41)/O(45).
/
Yb the two (approximate) square planes
and Er (which are isostructural and isomorphous) are
shown in Figs. 6 and 7, respectively (see also Table 3). In
both cases, binding of the lanthanide fragment to the
second bidentate site of L1 has resulted in two signifi-
cant changes in the conformation of the bridging ligand
L1. Firstly, the pyridyl and the imine N atoms at the
second coordination site are now necessarily mutually
cisoid so that they can coordinate. Secondly, there is a
/
Heterodinuclear complexes in which potentially lumi-
nescent d- and f-block chromophores are connected are
rare [9], but are desirable targets because of the
possibility of studying photoinduced energy- and elec-
tron-transfer between components in the way that is
very well known for complexes based solely on d-block
luminophores [1,2]. Although the mononuclear Re
greater twist about the central Nꢀ
/
N bond, such that the
angle between the mean planes of the two pyridyl rings
complexes of L1ꢀL4 are only weakly luminescent at
/
room temperature, the possibility of sensitised emission
from suitable lanthanide components by excitation of
the Re-based MLCT absorption still exists, especially at
lower temperatures. Such photophysical studies are in
progress and will be reported in due course.
3. Experimental
3.1. General details
The ligands L1 and L2 were prepared according to the
Fig. 6. Molecular structure of [Re(CO)3Cl(m-L1)Yb(hfac)3] with F
atoms omitted for clarity.
literature methods [6b,6e]. [Yb(hfac)3]×
/
2H2O and

N.M. Shavaleev et al. / Inorganica Chimica Acta 351 (2003) 159ꢀ
/166
163
UVꢀ
/
Vis absorption spectra were recorded on a Perkinꢀ
/
Elmer Lambda 2 spectrometer.
3.2. Synthesis of L3
This ligand was simply prepared by mixing together
hot ethanolic solutions of 2-formylpyridine (2 equiv.)
and 1,4-diaminobenzene (1 equiv.), upon which a yellow
precipitate quickly formed which was filtered off,
recrystallised from hot C2H5OH, and dried in vacuo.
Yield: 95%. Anal. Found: C, 75.7; H, 4.9; N, 19.5.
Required for C18H14N4: C, 75.5; H, 4.9; N, 19.6%. EI
MS: m/z 286 (Mꢂ). H NMR (270 MHz, CD2Cl2): d
1
8.70 (2H, ddd, pyridyl H6), 8.64 (2H, s, CH ꢂ
/N), 8.23
Fig. 7. Molecular structure of [Re(CO)3Cl(m-L1)Er(hfac)3] with F
atoms omitted for clarity. This view emphasises the approximately
square-antiprismatic geometry about the Er centre.
(2H, d, pyridyl H3), 7.83 (2H, td, pyridyl H4), 7.38 (6H,
m, pyridyl H5 and phenyl). L3 has been prepared
independently by Hannon and co-workers [11].
[Er(hfac)3]×
/
2H2O were also prepared by the published
method [10]. Organic reagents used for syntheses of L3
and L4, and metal complexes [Re(CO)5Cl], were ob-
tained from Aldrich and used as received. Electron-
impact (EI) and FAB mass spectra were recorded on a
VG-Autospec instrument; proton NMR spectra were
recorded on a JEOL GX-270 (270 MHz) spectrometer.
3.3. Synthesis of L4
A mixture of 2-acetylpyridine (3.0 g, 25 mmol), 1,4-
diaminobenzene (1.34 g, 12 mmol) and toluenesulphonic
acid (0.1 g, catalytic amount) was refluxed in dry,
degassed toluene (40 cm3) for 1 h. The reaction mixture
was then evaporated to dryness to leave a brownish-red
mixture of oil and crystals. The mixture was extracted
with boiling hexane, giving a yellow extract and leaving
a dark coloured residue. The hexane extract was
evaporated to dryness to give mixture of oil and crystals.
This residue was recrystallized twice from the minimum
amount of C2H5OH to give 1.01 g (26%) of the ligand L4
as a bright yellow solid. This ligand should be stored at
0 8C to prevent its discoloration. Anal. Found: C, 77.1;
H, 5.6; N, 17.9. Required for C20H18N4: C, 76.4; H, 5.8;
N, 17.8%. EI MS: m/z 314 (Mꢂ). NMR (270 MHz,
CD2Cl2): d 8.64 (2H, ddd, pyridyl H6), 8.28 (2H, d,
pyridyl H3), 7.80 (2H, td, pyridyl H4), 7.38 (2H, ddd,
pyridyl H5), 6.85 (4H, s, phenyl), 2.39 (6H, s, Me). L4
has been prepared independently by Hannon and co-
workers [11].
Table 2
Selected bond distances (A) for the mononuclear Re(I) complexes
˚
[Re(CO)3Cl(L1)]
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
/
C(41)
C(31)
C(51)
N(11)
N(18)
Cl(1)
1.915(5)
1.932(6)
1.933(6)
2.176(5)
2.190(5)
2.4775(14)
/
/
/
/
/
[Re(CO)3Cl(L2)]
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
/
C(41)
C(51)
C(61)
N(21)
N(11)
Cl(1)
1.913(4)
1.919(4)
1.919(4)
2.152(3)
2.176(3)
2.4862(10)
/
/
/
/
/
3.4. Synthesis of [Re(CO)3Cl(L1)]
[Re(CO)3Cl(L4)]
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
/
C(61)
C(61A)
C(71)
C(81)
N(21)
N(11)
Cl(1)
1.909(8)
1.911(14)
1.914(4)
1.918(4)
2.156(3)
2.167(3)
2.446(2)
2.449(7)
/
A mixture of [Re(CO)5Cl] (130 mg, 0.36 mmol) and
L1 (114 mg, 0.54 mmol, excess) in dry, degassed toluene/
CH2Cl2 (30 cm3, 3:1 v/v) was heated to reflux for 4 h
under N2. During the reaction, the solution gradually
changed colour from yellow to deep red, and a
brownish-red precipitate formed. The solution was
then cooled to 0 8C, and the precipitate was filtered
off, washed with hexane and ether, and vacuum dried to
give 136 mg (73%) of pure [Re(CO)3Cl(L1)]. Decom-
position of the complex was observed when column
chromatography on alumina was attempted. Anal.
Found: C, 34.7; H, 1.6; N, 10.4. Required for
C15H10ClN4O3Re: C, 34.9; H, 2.0; N, 10.9%. FAB
/
/
/
/
/
/
Cl(1A)
[Re(CO)3Cl(L5)]
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
/
C(41)
C(51)
C(61)
N(11)
N(21)
Cl(1)
1.916(4)
1.925(5)
1.945(5)
2.163(3)
2.179(3)
2.4839(11)
/
/
/
/
/

164
N.M. Shavaleev et al. / Inorganica Chimica Acta 351 (2003) 159ꢀ166
/
Table 3
while hot, and the precipitate was washed with hexane
and ether and vacuum dried to give 83 mg (66%) of
orange [Re(CO)3Cl(L2)]. The complex obtained was
analytically pure, however, if necessary it could be
additionally purified by column chromatography on
alumina eluting with CH2Cl2. Anal. Found: C, 37.8; H,
2.2; N, 9.9. Required for C17H14ClN4O3Re: C, 37.5; H,
˚
Selected bond distances (A) and angles (8) for the dinuclear complexes
[Re(CO)3Cl(L1)Yb(hfac)3]: Lnꢁ
Er (left) or Yb (right)
/
Bond distances
Er(1)ꢀ
Er(1)ꢀ
Er(1)ꢀ
Er(1)ꢀ
Er(1)ꢀ
Er(1)ꢀ
Er(1)ꢀ
Er(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
/
O(61)
O(45)
O(55)
O(41)
O(51)
O(65)
N(31)
N(22)
2.287(3)
2.294(3)
2.294(3)
2.295(3)
2.307(3)
2.309(3)
2.494(4)
2.627(3)
1.901(5)
1.919(5)
1.924(5)
2.169(4)
2.178(3)
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
Re(1)ꢀ
/
O(61)
O(55)
O(51)
O(45)
O(41)
O(65)
N(31)
N(22)
2.274(4)
2.276(3)
2.276(4)
2.281(3)
2.293(4)
2.305(4)
2.472(4)
2.617(4)
1.912(6)
1.919(6)
1.919(6)
2.178(4)
2.186(4)
2.4717(14)
/
/
/
/
/
/
2.6; N, 10.3%. FAB MS: m/z 568 (8%, {Mꢂ
(13%, Mꢂ); 509 (100%, {MꢃCl}ꢂ). Successive loss of
the three CO and the chloride ligands was also apparent.
IR (CH2Cl2), cmꢃ1
Vis
/
Na}ꢂ); 545
/
/
/
/
/
/
/
/
/
:
2025, 1927, 1900. UVꢀ
/
(CH2Cl2), lmax (nm) (o, Mꢃ1 cmꢃ1): 402 (4260), 289
(19100). X-ray quality crystals were grown by slow
evaporation of a CH2Cl2/hexane solution of the com-
plex.
/
C(81)
C(71)
C(91)
N(11)
N(21)
Cl(1)
/
C(91)
C(71)
C(81)
N(11)
N(21)
Cl(1)
/
/
/
/
/
/
/
/
/
2.4676(12) Re(1)ꢀ
/
3.6. Synthesis of [Re(CO)3Cl(L3)] and of
[Re(CO)3Cl(L5)]
Bond angles
O(61)ꢀEr(1)ꢀ
O(61)ꢀEr(1)ꢀ
O(45)ꢀEr(1)ꢀ
O(61)ꢀEr(1)ꢀ
O(45)ꢀEr(1)ꢀ
O(55)ꢀEr(1)ꢀ
O(61)ꢀEr(1)ꢀ
O(45)ꢀEr(1)ꢀ
O(55)ꢀEr(1)ꢀ
O(41)ꢀEr(1)ꢀ
O(61)ꢀEr(1)ꢀ
O(45)ꢀEr(1)ꢀ
O(55)ꢀEr(1)ꢀ
O(41)ꢀEr(1)ꢀ
O(51)ꢀEr(1)ꢀ
O(61)ꢀEr(1)ꢀ
O(45)ꢀEr(1)ꢀ
O(55)ꢀEr(1)ꢀ
O(41)ꢀEr(1)ꢀ
O(51)ꢀEr(1)ꢀ
O(65)ꢀEr(1)ꢀ
O(61)ꢀEr(1)ꢀ
O(45)ꢀEr(1)ꢀ
O(55)ꢀEr(1)ꢀ
O(41)ꢀEr(1)ꢀ
O(51)ꢀEr(1)ꢀ
O(65)ꢀEr(1)ꢀ
N(31)ꢀEr(1)ꢀ
/
/
O(45) 144.04(11) O(61)ꢀ
/
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
Yb(1)ꢀ
/
O(55) 144.52(13)
75.00(14)
73.76(13)
/
/
O(55) 120.17(11) O(61)ꢀ
/
/O(51)
/
/
O(55)
O(41)
O(41)
79.34(10) O(55)ꢀ
74.89(11) O(61)ꢀ
73.47(11) O(55)ꢀ
/
/O(51)
A mixture of [Re(CO)5Cl] (73 mg, 0.20 mmol) and L3
(277 mg, 0.97 mmol, excess) were heated at 60ꢀ65 8C for
/
/
/
/
O(45) 119.76(14)
O(45) 79.07(12)
O(45) 143.95(13)
O(41) 72.57(14)
/
/
/
/
/
6 h in dry degassed toluene (30 cm3) under N2. The
relatively low temperature and the large excess of ligand
are necessary to prevent formation of the undesired
dinuclear complex. During the course of reaction a dark
orange precipitate formed. The reaction mixture was
cooled to room temperature (r.t.); the precipitate was
filtered off, and washed with hexane and ether to give 80
mg (67%) of [Re(CO)3Cl(L3)]. Anal. Found: C, 42.6; H,
2.0; N, 9.4. Required for C21H14ClN4O3Re: C, 42.6; H,
/
/
O(41) 144.52(12) O(51)ꢀ
O(51)
72.80(12) O(61)ꢀ
O(51) 142.96(10) O(55)ꢀ
O(51)
74.02(11) O(51)ꢀ
O(51) 139.90(11) O(45)ꢀ
/
/
/
/
/
/
/
/
/
/O(41) 142.74(13)
/
/
/
/O(41) 139.65(14)
/
/
/
/
O(41)
O(65)
O(65)
O(65)
O(65)
74.72(12)
74.26(13)
82.87(12)
77.40(13)
76.10(13)
/
/
O(65)
O(65)
O(65)
O(65)
73.97(11) O(61)ꢀ
83.05(10) O(55)ꢀ
76.62(10) O(51)ꢀ
77.84(11) O(45)ꢀ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
O(65) 114.44(11) O(41)ꢀ
N(31)
78.94(12) O(61)ꢀ
N(31) 107.52(11) O(55)ꢀ
N(31) 137.81(11) O(51)ꢀ
/
/
O(65) 115.18(13)
N(31) 79.25(14)
N(31) 107.26(14)
N(31) 73.61(14)
N(31) 138.30(13)
N(31) 77.31(14)
/
/
/
/
2.4; N, 9.5%. FAB MS: m/z 593 (26%, {Mꢂ
(23%, {Mꢃ
Cl}ꢂ). IR (CH2Cl2), cmꢃ1: 2026, 1928,
1902. UVꢀ
Vis (CH2Cl2), lmax (nm) (o, Mꢃ1 cmꢃ1): 365
/
H}ꢂ), 557
/
/
/
/
/
/
/
/
/
/
/N(31)
73.42(12) O(45)ꢀ
/
/
/
/
/N(31)
77.61(12) O(41)ꢀ
/
/
(16500), 275 (sh) (20600), 250 (sh) (22500).
/
/
N(31) 144.64(11) O(65)ꢀ
/
/N(31) 144.80(13)
[Re(CO)3Cl(L3)] was usually obtained pure by this
method, but in one case was slightly contaminated with
the dinuclear complex so was subjected to column
/
/
N(22) 133.87(11) O(61)ꢀ
/
/N(22) 133.86(13)
/
/N(22)
76.91(10) O(55)ꢀ
/
/
N(22)
76.71(12)
N(22) 117.59(13)
/
/N(22)
77.28(11) O(51)ꢀ
/
/
/
/
N(22) 117.05(11) O(45)ꢀ
N(22)
72.50(11) O(41)ꢀ
N(22) 149.53(10) O(65)ꢀ
N(22)
64.67(11) N(31)ꢀ
/
/
N(22)
77.51(13)
72.14(13)
N(22) 149.16(13)
chromatography.
A
129 mg sample of crude
[Re(CO)3Cl(L3)] was dissolved in THF and loaded on
to an alumina column. Elution with acetone/CH2Cl2
(1:4) gave a main orange band which after evaporation
afforded 30 mg of a red product which proved to be the
decomposition product [Re(CO)3Cl(L5)]. Anal. Found:
C, 35.7; H, 2.1; N, 7.5. Required for C15H11ClN3O3Re:
/
/
/
/N(22)
/
/
/
/
/
/
/
/
N(22) 64.75(13)
MS: m/z 539 (25%, {Mꢂ
(18%, {Mꢃ
Cl}ꢂ). IR (CH2Cl2), cmꢃ1: 2028, 1929,
1907. UVꢀ
Vis (CH2Cl2), lmax (nm) (o, Mꢃ1 cmꢃ1): 437
/
Na}ꢂ); 516 (12%, Mꢂ); 479
/
C, 35.8; H, 2.2; N, 8.4%. FAB MS: m/z 526 (6%, {Mꢂ
/
/
Na}ꢂ), 503 (20%, Mꢂ), 468 (38%, {MꢃCl}ꢂ). X-ray
quality crystals were grown by slow evaporation of a
THF/heptane solution of the complex.
/
(3070), 312 (20600). X-ray quality crystals were grown
by slow evaporation of a CH2Cl2/hexane solution of the
complex.
3.7. Synthesis of [Re(CO)3Cl(L4)]
3.5. Synthesis of [Re(CO)3Cl(L2)]
A mixture of [Re(CO)5Cl] (100 mg, 0.28 mmol) and
L4 (174 mg, 0.55 mmol, excess) in dry degassed dry
hexane (90 cm3) was heated to reflux for 4 h under N2,
during which time an orange precipitate formed. The
reaction mixture was filtered while hot, and the pre-
A mixture of [Re(CO)5Cl] (83 mg, 0.23 mmol) and L2
(158 mg, 0.66 mmol, excess) in degassed hexane (30 cm3)
was heated to reflux for 4 h under N2, during which time
an orange precipitate formed. The solution was filtered

N.M. Shavaleev et al. / Inorganica Chimica Acta 351 (2003) 159ꢀ
/166
165
cipitate was washed with hexane and ether to give 132
mg (77%) of bright orange [Re(CO)3Cl(L4)]. The com-
plex could be handled in air, however, it is recom-
mended to store it under N2 and at 0 8C, because a
change of colour from bright orange to brownish-
orange was observed after 1 month of storage in air at
r.t. Anal. Found: C, 44.7; H, 2.7; N, 8.9. Required for
C23H18ClN4O3Re: C, 44.6; H, 2.9; N, 9.0%. FAB MS:
the metal centre for the complex with L1 are associated
with absorption effects and are not chemically signifi-
cant. For both dinuclear complexes [Re(CO)3Cl(m-
L1)Ln(hfac)3] the thermal parameters associated with
the F atoms on the CF3 groups are considerably larger
than for all other non-H atoms due to the facile
rotational motion of these groups.
m/z 643 (12%, {Mꢂ
/
Na}ꢂ), 621 (8%, Mꢂ), 585 (18%,
Vis (CH2Cl2), lmax (nm) (o, Mꢃ1
3.10. Luminescence studies
{Mꢃ
/
Cl}ꢂ). UVꢀ
/
cmꢃ1): 407 (sh) (5300), 341 (6050), 271 (sh) (27500),
237 (36300). X-ray quality crystals were grown by slow
evaporation of a THF/heptane solution of the complex.
Luminescence spectra were obtained from air-equili-
brated dilute solutions (2ꢄ
10ꢃ5 M) of the investigated
/
complexes by using a Spex Fluorolog II spectrofluori-
meter, equipped with a Hamamatsu R928 phototube.
The spectra were uncorrected, and the determination of
the luminescence quantum yield, F was done with
3.8. Syntheses of [Re(CO)3Cl(m-L1)Ln(hfac)3] (Lnꢁ
Yb, Er)
/
reference to [Ru(bpy)3]2ꢂ as a standard (Fꢁ
/
0.028 in
These were all prepared by slow evaporation of a
mixed C6H6ꢀheptane solution (1:1, total volume 10ꢀ15
cm3) containing equimolar amounts of [Re(CO)3Cl(L1)]
and the appropriate [Ln(hfac)3]×2H2O (typically, 0.1
mmol). After 10ꢀ14 days large, dark red crystals of the
air-equilibrated water) and by using a procedure illu-
strated elsewhere [2]. Luminescence lifetimes were ob-
tained using an IBH single-photon counting
spectrometer equipped with a nitrogen-filled thyratron
gated lamp (lexc 337 or 358 nm). The uncertainty in
band maximum and lifetime values is within 2 nm and
8%, respectively.
/
/
/
/
adducts formed in approximately 90% yield. Data for
[Re(CO)3Cl(m-L1)Er(hfac)3] follow. [Re(CO)3Cl(L1)] (40
mg, 78 mmol) and [Er(hfac)3]×2H2O (64 mg, 78 mmol)
/
gave 94 mg (93% yield) of the dinuclear product. Anal.
Found: C, 27.6; H, 1.0; N, 4.3. Required for
C30H13ClErF18N4O9Re: C, 27.9; H, 0.9; N, 4.3%. IR
4. Supplementary material
(CH2Cl2), cmꢃ1: 2032, 1931 (asymmetric peak). UVꢀ
/
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC Nos. 197699ꢀ197704. Copies of
Vis (CH2Cl2), lmax (nm) (o, Mꢃ1 cmꢃ1): 457 (2570), 293
(51800).
/
this information may be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge, CB2
3.9. X-ray crystallography
1EZ, UK (fax: ꢂ44-1223-336-033; email: deposit@ccd-
c.ac.uk; or www: http://www.ccdc.cam.ac.uk).
/
Details of the crystal, data collection and refinement
parameters for the new structures are summarised in
Table 1. In each case, structure solution and refinement
used the SHELX package (version 5.03) comprising
SHELXS-97 [12] and SHELXL-97 [13]; absorption correc-
tions were applied to the data using SADABS [14]. H
atoms were included in calculated positions with iso-
tropic thermal parameters, and refined as riding atoms.
In [Re(CO)3Cl(L4)], the Cl ligand and the CO group
trans to it [C(61) and O(61)] were mutually disordered,
with each group being present in lone location with a
site occupancy of 75% and the other with a site
occupancy of 25%. Geometric restraints were used to
Acknowledgements
We thank the Royal Society/NATO for a post-
doctoral fellowship (to N.M.S.) and EPSRC for a
post-doctoral fellowship (to Z.R.B.). G.A. thanks Con-
sorzio Spinner E.R. for financing the project ‘TT/
Photomed-184/02’.
References
ensure that the Reꢀ
/
Cl, Reꢀ
/
C and Cꢀ/O separations in
the major and minor disorder components were similar
to one another. The atoms involved in the minor
component of the CO disorder [atoms C(61)A and
O(61)A] gave unreasonable anisotropic thermal para-
meters and were accordingly refined isotropically. The
structural determinations of the remaining mononuclear
[1] (a) V. Balzani, S. Campagna, G. Denti, A. Juris, S. Serroni, M.
Venturi, Acc. Chem. Res. 31 (1998) 26;
(b) V. Balzani, A. Juris, M. Venturi, S. Campagna, S. Serroni,
Chem. Rev. 96 (1996) 759;
(c) F. Barigelletti, L. Flamigni, Chem. Soc. Rev. 29 (2000) 1;
(d) A.K. Burrell, D.L. Officer, P.G. Plieger, D.C.W. Reid, Chem.
Rev. 101 (2001) 2751;
complexes [Re(CO)3Cl(Ln)] (nꢁ
forward; large residual electron-density peaks close to
/1, 2, 5) were straight-
(e) C.A. Bignozzi, R. Argazzi, C.J. Kleverlaan, Chem. Soc. Rev.
29 (2000) 87;

166
N.M. Shavaleev et al. / Inorganica Chimica Acta 351 (2003) 159ꢀ166
/
(f) R. Ziessel, M. Hissler, A. El-Ghayoury, A. Harriman, Coord.
Chem. Rev. 180 (1998) 1251;
[6] (a) J. Hamblin, A. Jackson, N.W. Alcock, M.J. Hannon, J. Chem.
Soc., Dalton Trans. (2002) 1635;
(g) J.-P. Sauvage, J.-P. Collin, J.-C. Chambron, S. Guillerez, C.
Coudret, V. Balzani, F. Barigelletti, L. De Cola, L. Flamigni,
Chem. Rev. 94 (1994) 993.
(b) W.J. Stratton, D.H. Busch, J. Am. Chem. Soc. 80 (1958) 1286;
(c) W.J. Stratton, D.H. Busch, J. Am. Chem. Soc. 82 (1960) 4834;
(d) W.J. Stratton, D.H. Busch, J. Am. Chem. Soc. 80 (1958) 3191;
(e) W.J. Stratton, Inorg. Chem. 9 (1970) 517.
[2] (a) A. Farran Morales, G. Accorsi, N. Armaroli, F. Barigelletti,
S.J.A. Pope, M.D. Ward, Inorg. Chem. 41 (2002) 6711;
(b) N.R.M. Simpson, M.D. Ward, A. Farran Morales, F.
Barigelletti, J. Chem. Soc., Dalton Trans. (2002) 2449;
(c) S.J.A. Pope, C.R. Rice, M.D. Ward, A.F. Morales, G.
Accorsi, N. Armaroli, F. Barigelletti, J. Chem. Soc., Dalton
Trans. (2001) 2228;
[7] (a) M.J. Hannon, C.L. Painting, N.W. Alcock, Chem. Commun.
(1999) 2023;
(b) M.J. Hannon, S. Bunce, A.J. Clarke, N.W. Alcock, Angew.
Chem., Int. Ed. 38 (1999) 1277.
[8] (a) K. Iftikhar, M. Sayeed, N. Ahmad, Inorg. Chem. 21 (1982) 80;
(b) W.H. Watson, R.J. Williams, N.R. Stemple, J. Inorg. Nucl.
Chem. 34 (1982) 501;
(d) S. Encinas, A.M. Barthram, M.D. Ward, F. Barigelletti, S.
Campagna, Chem. Commun. (2001) 277.
(c) S. Yajima, Y. Hasegawa, Bull. Chem. Soc. Jpn. 71 (1998) 2825.
[9] (a) A. Beeby, R.S. Dickins, S. FitzGerald, L.J. Govenlock, C.L.
Maupin, D. Parker, J.P. Riehl, G. Siligardi, J.A.G. Williams,
Chem. Commun. (2000) 1183;
[3] (a) R.N. Dominey, B. Hauser, J. Hubbard, J. Dunham, Inorg.
Chem. 30 (1991) 4754;
(b) B.D. Rossenaar, C.J. Kleverlaan, M.C.E. VanDeVen, D.J.
Stufkens, A. Oskam, J. Fraanje, K. Goubitz, J. Organomet.
Chem. 493 (1995) 153.
(b) S.I. Klink, H. Keizer, F.C.J.M. van Veggel, Angew. Chem.,
Int. Ed. 39 (2000) 4319;
[4] (a) L.A. Worl, R. Duesing, P. Chen, L. Della Ciana, T.J. Meyer,
J. Chem. Soc., Dalton Trans. (1991) 849;
(c) N.M. Shavaleev, Z.R. Bell, M.D. Ward, J. Chem. Soc., Dalton
Trans. (2002) 3925;
(b) A. Juris, S. Campagna, I. Bidd, J.-M. Lehn, R. Ziessel, Inorg.
Chem. 27 (1988) 4007.
(d) M. Cantuel, G. Bernardinelli, D. Imbert, J.-C.G. Bunzli, G.
Hopfgartner, C. Piguet, J. Chem. Soc., Dalton Trans. 1 (2002)
1929;
[5] (a) W.D. Horrocks, J.P. Bolender, W.D. Smith, R.M. Supkowski,
J. Am. Chem. Soc. 119 (1997) 5972;
(e) M.A. Rawashdeh-Omary, C.L. Larochelle, H.H. Patterson,
Inorg. Chem. 39 (2000) 4527.
(b) A. Beeby, S. Faulkner, D. Parker, J.A.G. Williams, J. Chem.
Soc., Perkin Trans. 2 (2001) 1268;
[10] M.F. Richardson, W.F. Wagner, D.E. Sands, J. Inorg. Nucl.
Chem. 30 (1968) 1275.
[11] M.J. Hannon, personal communication.
(c) A. Beeby, B.P. Burton-Pye, S. Faulkner, G.R. Motson, J.C.
Jeffery, J.A. McCleverty, M.D. Ward, J. Chem. Soc., Dalton
Trans. (2002) 1923;
[12] G.M. Sheldrick, SHELXS-97: A Program for Automatic Solution
(d) M.H.V. Werts, J.W. Verhoeven, J.W. Hofstraat, J. Chem.
Soc., Perkin Trans. 2 (2000) 433;
of Crystal Structures, University of Gottingen, Gottingen,
¨ ¨
Germany, 1997.
[13] G.M. Sheldrick, SHELXL-97: A Program for Crystal Structure
Refinement, University of Gottingen, Gottingen, Germany, 1997.
(e) S. Faulkner, A. Beeby, R.S. Dickins, D. Parker, J.A.G.
Williams, J. Fluoresc. 9 (1999) 45;
¨
¨
(f) M.H.V. Werts, J.W. Hofstraat, F.A.J. Geurts, J.W. Verhoe-
ven, Chem. Phys. Lett. 276 (1997) 196;
[14] G.M. Sheldrick, SADABS: A Program for Absorption Correction
of Crystallographic Data, University of Gottingen, Gottingen,
(g) A.I. Voloshin, N.M. Shavaleev, V.P. Kazakov, J. Lumin. 93
(2001) 115.
¨
¨
Germany, 1996.