Re(i) derivatives functionalised with thioether crowns containing the 1,10-phenanthroline subunit as a new class of chemosensors

Article abstract of DOI:10.1039/c5dt02723c

A series of luminescent fac-[Re(CO)₃(L)(NN)]⁺ complexes, where L is a pyridine or an imidazole and NN is the 1,10-phenanthroline subunit of mixed donor pentadentate thioether crowns have been synthesised and their luminescence properties have been analysed. Then, heterometallic Re(i)/Au(i) complexes, with the Au(i) fragment bonded directly to the imidazole ligand, and heterometallic Re(i)/Ag(i) complexes, with the silver fragment coordinating the S-donor thioether linker of the rings have also been prepared. Analysis of their luminescence properties showed a considerable blue shift of the emission maxima for the Re(i)/Ag(i) derivatives, upon coordination of the silver centre to the S-donor atoms of the aliphatic chain of the macrocyclic units.

Full text of DOI:10.1039/c5dt02723c

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Re(I) derivatives functionalised with thioether
crowns containing the 1,10-phenanthroline
Cite this: DOI: 10.1039/c5dt02723c
subunit as a new class of chemosensors†
Arianna Casula,a,b Valentina Nairi,a,b Vanesa Fernández-Moreira,*a Antonio Laguna,a
Vito Lippolis,*b Alessandra Garaub and M. Concepción Gimeno*a
A series of luminescent fac-[Re(CO)3(L)(NN)]+ complexes, where L is a pyridine or an imidazole and NN is
the 1,10-phenanthroline subunit of mixed donor pentadentate thioether crowns have been synthesised
and their luminescence properties have been analysed. Then, heterometallic Re(I)/Au(I) complexes, with
the Au(I) fragment bonded directly to the imidazole ligand, and heterometallic Re(I)/Ag(I) complexes, with
the silver fragment coordinating the S-donor thioether linker of the rings have also been prepared.
Analysis of their luminescence properties showed a considerable blue shift of the emission maxima for
the Re(I)/Ag(I) derivatives, upon coordination of the silver centre to the S-donor atoms of the aliphatic
chain of the macrocyclic units.
Received 20th July 2015,
Accepted 21st September 2015
DOI: 10.1039/c5dt02723c
www.rsc.org/dalton
scence properties.3 Regardless of the great amount of work
devoted to the development of rhenium(I) based transition
Introduction
Since the pioneering work of Pedersen, Lehn and Cram invol- metal complexes as selective sensors for either alkali and alka-
ving the synthesis of cation selective crown ethers, cryptands line earth metals,4 only a few examples have been reported as
and spherands,1 many studies have been devoted to the deve- chemosensors of transition metals. The incorporation of soft
lopment of selective receptors for host–guest interactions and donor atoms like sulfur or selenium into crown units is key for
molecular recognition. Their wide application in the area of achieving such selectivity. Several examples reported by Yam
ion transport and chemosensing makes this research field very and coworkers demonstrated that functionalised rhenium(I)
appealing. In this sense, transition d6 metal complexes have derivatives with thia-, selena- and azacrown moieties can be
lately attracted much interest due to their versatile photo- used for selective and specific binding of soft metal ions such
physical and photochemical properties.2 In general they Ag+, Hg2+ and/or Pb2+.5 This work aims to increase the scope
showed metal-to-ligand charge transfer (MLCT) transitions, of soft metal ion sensors by developing new rhenium(I)
with relatively large Stokes shifts, long lifetimes and good systems bearing thia and mixed thia/oxo aliphatic linkers
quantum yields. In the particular case of luminescent anchored directly to the diimine unit. Functionalisation at the
rhenium(I) complexes, the archetypal system is [Re(CO)3(L)- 2,9-positions of the diimine rather than the axial ligand bound
(NN)]0/+1 where (NN) represents a diimine derivative and L is a to the rhenium(I) centre will be preferred in order to affect
halogen atom or pyridine derivative. The specific phosphore- directly the electronic properties of the ligand portion impli-
scence process is, generally, a 3MLCT transition originating cated in the emission process.
from a Re(dπ) → NN(π*) excited state, where the rest of the
ligands in the coordination sphere barely affect the lumine-
Results and discussion
Synthetic procedure and characterization
aDepartamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis
Homogénea (ISQCH), Universidad de Zaragoza-CSIC, E-50009 Zaragoza, Spain.
The synthesis of the macrocyclic ligands L1 and L2 has been
E-mail: gimeno@unizar.es, vanesa@unizar.es; Fax: +34 976761187;
described somewhere else and it is summarised in Scheme 1.6
Tel: +34 976762291
bDipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari,
Briefly, it entailed the oxidation of 2,9-dimethyl-1,10-phenan-
throline to the corresponding dialdehyde, then its reduction to
2,9-bis(hydroxymethy1)-1,10-phenanthroline and thereafter a
S.S. 554 Bivio per Sestu, 09042-Monserrato(CA), Italy. E-mail: lippolis@unica.it
†Electronic supplementary information (ESI) available: Short contact interaction
in complex 5 (Fig. S1); emission spectra of complexes 1, 2, 5–12 and 8 (Fig. S2).
chlorination step followed by a cyclisation reaction with the
CCDC 1413449–1413455. For ESI and crystallographic data in CIF or other elec-
tronic format see DOI: 10.1039/c5dt02723c
correspondent dithiol to afford L1 and L2.7
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Scheme 2 Depiction of the synthesis of species 1–8 (i): [ReCl(CO)5],
toluene, reflux 1 h; (ii) Ag(CF3SO3), acetone, r.t. 12 h; (iii) Py/ImH, THF/
acetone, r.t., 1d/4d.
Scheme 1 Depiction of the synthesis of ligands L1 and L2 with the
numbering scheme adopted for 1H and 13C NMR assignments. (i): SeO2,
dioxane, reflux; 4 h; (ii) NaBH4, ethanol, reflux 2 h; (iii) SOCl2, r.t., 8 h; (iv)
(HSCH2CH2)2S (L1) or (HSCH2CH2)2O (L2), Cs2CO3, dimethylformamide
(dmf), 55 °C.
Complexes fac-[Re(Cl)(CO)3(L1)] (1) and fac-[Re(Cl)-
(CO)3(L2)] (2) were obtained by reaction of the commercially
available [Re(Cl)(CO)5] with the previously synthesised L1 and
L2, which involved the substitution of two carbonyl ligands for
the nitrogen atoms of the phenanthroline subunit of L1 and
L2. The adopted bidentate coordination mode of L1 and L2
contrasted with that previously observed for Pb(II), Rh(III),
Ni(II), and Ru(II) complexes.6a,8 In those cases, L1 and L2
bound the metal centre through the nitrogen atoms as well as
the heteroatoms of the mixed thioether crown, affording either
octahedral or tetrahedral complexes. Therefore, the bidentate
coordination mode observed for the complexes described
herein might be the reason for the severe distortion present in
the phenanthroline unit, which contrary to what was expected,
was not lying in the equatorial plane defined by the two nitro-
gen atoms and the trans carbonyl ligands. This particular dis-
position will be discussed in detail in the sections below.
Complexes fac-[Re((CH3)2CO)(CO)3(L1)](CF3SO3) (3) and fac-
[Re((CH3)2CO)(CO)3(L2)](CF3SO3) (4), which can be considered as
activated intermediate species, were obtained by abstraction of
the chloride ligand with silver triflate in a coordinating solvent.
Finally, the cationic complexes fac-[Re(CO)3(L)(L1)](CF3SO3) and
fac-[Re(CO)3(L)(L2)](CF3SO3) [L = ImH (5, 7), Py (6, 8)] were syn-
thesised by reaction of the activated rhenium(I) complexes 3 and
4 with either pyridine or imidazole, see Scheme 2.
Scheme 3 Depiction of the synthesis of complexes 9–10 (i): Cs2CO3,
[Au(CF3SO3)(PPh3)], dichloromethane, r.t., 1–2 h.
Scheme 4 Depiction of the synthesis of complexes 11 and 12 with the
proposed structure in solution (i): Ag(CF3SO3), acetone, r.t., 1–3d.
The synthesis of the heterometallic complexes fac-
[Re(CO)3(L1)(ImAu(PPh3))](CF3SO3) (9) and fac-[Re(CO)3(L2)-
(ImAu(PPh3))](CF3SO3) (10) was performed successfully by
assisting the deprotonation of the imidazole ligand in com-
plexes 5 and 7 with Cs2CO3 in the presence of [Au(CF3SO3)-
(PPh3)], see Scheme 3.9 In addition, complexes 6 and 8 were
treated with Ag(CF3SO3) in acetone affording the heterometal-
lic complexes fac-[Re(CO)3(L1)(Py)Ag](CF3SO3)2 (11) and fac-
[Re(CO)3(L2)(Py)Ag](CF3SO3)2 (12), see Scheme 4. Spectroscopic
characterization was performed using IR, 1H, 13C-NMR, and
UV-vis spectroscopy. Further analytical data for each complex
was provided through mass spectrometry and, in specific
cases, by elemental analysis thus, corroborating the accom-
plishment of the synthesis of the mono- and heterometallic
species. Additionally, crystals of 2, 5, 6, 7, 8, 11 and 12 suitable
for X-ray analysis (SHELX programs) were obtained by slow
diffusion of ether or hexane into a solution of the complex in
dichloromethane or acetone.
1H-NMR spectroscopy of complexes 1–12 was performed in
either acetone-d6 or dichloromethane-d2. In all cases, the
spectra are well defined and exhibit the characteristic down-
field shift of the aromatic protons upon coordination to the
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rhenium metal centre when compared to the corresponding
proton resonances of the free ligand. This phenomenon is
generally rationalised in terms of the σ donation of the che-
lated ligand.10,6a It is important to point out the appearance of
only four set of signals in the aromatic region belonging to the
diimine ligand L1 or L2 for complexes 1–12, which indicates
its symmetry within the complex.11 Moreover, a more compli-
cated pattern is seen for the aliphatic protons as a conse-
quence of their different environment upon coordination to
the rhenium metal centre. Thus, these pairs of diastereotopic
protons are either pointing in, towards the coordination
sphere of the metal centre, or outwards, affording an AB sub-
spectrum for methylenic protons CH2(11 and 19) and ABXY
systems for CH2(13, 14, 16 and 17). The same features have
been previously reported for similar complexes of Rh(III),
Ru(II), Pt(II) and Pd(II).6 13C-NMR spectra showed six and three
peaks in the aromatic and aliphatic region respectively, belong-
ing to either L1 or L2 in each complex. This indicates the exist-
ence of a plane of symmetry passing through the Re(I) atoms,
S(15)/O(15) atoms and the ligands coordinated to the metal in
the axial position and therefore, implying that the CO ligands
adopt a facial disposition rather than meridional. In compari-
son with the uncoordinated ligands L1 and L2, a drastic down-
field shift, particularly for C(2) and C(9) from ca. 158 ppm to
ca. 168 ppm, was observed after complexation. In contrast, the
chemical shift of aliphatic carbons remained practically the
same in complexes 1–10 indicating that none of the S or
O atoms are implicated in the complexation of the Re(I) atom.
Moreover, 31P-NMR spectroscopy was performed for species
9 and 10 showing a single peak at 32 ppm, which is in the
typical range of values for an N–Au–P environment.12 In
addition to that, protons of the imidazole fragment are
shielded upon the complexation of the gold fragment and in
consequence they are shifted upfield. In the case of the hetero-
metallic complexes 11 and 12, the 1H-NMR spectroscopy
showed that the aliphatic protons are lowfield shifted in com-
parison with their monometallic precursors. Specifically, in
complex 11 CH2(14) and CH2(16) protons moved from
1.63 ppm and 2.24 ppm to 1.80 and 2.40 ppm respectively,
suggesting that S(15) is coordinated to the silver(I) atom. The
lack of shifts for both, CH2(11) and CH2(19) protons in compari-
son with those of its precursor complex 6, together with the
symmetry observed in the 1H-NMR spectrum (AB system for
CH2(11, 19) and ABXY for CH2(13–17)) proposes the S(15) atom
as the only coordinative site in solution, Scheme 4 and Fig. 1.
The same 1H-NMR pattern was observed for complex 12,
thus, indicating once again that symmetric species are present
in solution. In this case, CH2(11) and CH2(19) protons are
shifted from 4.99 ppm and 4.73 ppm to 5.19 ppm and
4.85 ppm, pointing towards S(12) and S(18) as the coordinative
sites of the silver atom. A fluxional process, where the coordi-
nation of the silver atom is swapping from the sulfur atoms
S(12) and S(18), is feasible in solution, granting in this way the
symmetry observed by NMR spectroscopy.
Fig. 1 1H-NMR spectrum of complex 11.
Table 1 IR stretching frequencies and relevant 1H-NMR and 13C-NMR
chemical shifts for complexes 1–12 and L1 and L2
Compound ν(CuO)
δ(C2/9) δ(H)(C3/8) δ(H)(C11/19)
L1
L2
1
—
—
159.5a 8.21a
158.9b 8.26b
165.7a 8.49a
4.11 (s)
4.07 (s)
4.92 (d),
4.39(d)
4.77 (d),
4.41 (d)
2012, 1884
2
2017, 1910, 1882
166.0a 8.48a
3
4
2031, 1932(sh), 1904
—
9.04
2033, 1932(sh), 1903 165.1c
8.99c
5.33 (d),
5.05 (d)
4.91 (s)
4.97 (d)
4.90 (d)
4.92 (d),
4.74 (d)
4.99 (d),
4.73 (d)
4.91 (q)
4.90 (d)
4.76 (d)
5.02 (d)
4.93 (d)
5.19 (d)
4.85 (d)
5
6
2024, 1909(sh), 1887 169.4c
2029, 1932(sh), 1914 169.8c
8.86c
8.88c
7
8
2033, 1937(sh), 1920 169.7c
2028, 1936(sh), 1904 170.2c
8.84c
8.86c
9
10
2023, 1932(sh), 1882
—
8.84c
8.82c
2024, 1931(sh), 1895 169.2c
2031, 1932(sh), 1918 169.6c
2034, 1937(sh), 1923 170.2c
11
12
8.89c
8.90c
a Dichloromethane-d2. b CDCl3. c (Acetone-d6). (sh) shoulder.
Table 1. The IR spectra of complexes 1–12 showed the charac-
teristic strong ν(CO) absorptions in the range between 1882
and 2037 cm−1. Those values suggest an approximate C3v sym-
metry around the rhenium centre, i.e. facial configuration, in
line with 1H and 13C-NMR spectroscopic data.6,13 Moreover the
shift of the symmetric stretching mode from 2012 cm−1 and
2017 cm−1 in complexes 1 and 2 to ca. 2030 cm−1 in complexes
3–12 indicates the transition from the neutral rhenium species
1 and 2 to cationic species.13a
X-ray crystallography
Additional data on relevant 1H-NMR, 13C-NMR chemical Single crystals suitable for X-ray diffraction analysis of com-
shifts and stretching frequencies of CO are presented in plexes 2, 5, 6, 7 and fac-[Re(CO)3(Py)(L2)](PF6)·CH2Cl2 (8′) were
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obtained by slow diffusion of diethyl ether or hexane into a unit (compounds 5 and 7) or (c) a pyridine unit (compounds 6
solution of the complex in either dichloromethane or acetone, and 8′). Deviation from the ideal octahedral disposition is
see Fig. 2. Compounds 2, 5 and 7 crystallised in a monoclinic mostly originating from the geometric restraints imposed by
P2(1)/c space group, whereas complex 6 in a monoclinic P2(1)/n L1 and L2. In each complex, the chelated angle N–Re–N is
ˉ
space group and complex 8′ in a triclinic P1 space group. All of around 74° instead of the ideal 90°. Bond distances in the
them showed a single molecule per asymmetric unit and the cat- rhenium core are within the typical values, i.e. Re–CO dis-
ionic species crystallised with their correspondent counterion. tances are between 1.899(4) Å and 1.943(12) Å, Re–Cl is
Moreover, compounds 7 and 8′ also presented a crystallisation 2.4963(10) Å and Re–N(ImH/py) is between 2.1803(19) Å and
solvent molecule, acetone and dichloromethane respectively in 2.215(4) Å.14 Contrary to the complexes already reported with
the asymmetric unit. The crystal structure of complex 8′, ana- L1 and L2, where the metal centre was directly coordinated to
logous to 8, but with PF6− as a counterion, has been obtained by the chelate ligand and the heteroatoms from the aliphatic
a metathesis reaction of the initially prepared triflate salt 8 with chain within the macrocyclic cavity, the rhenium metal centre
KPF6. Only in the case of complex 5 a short contact between one left the heteroatoms of the aliphatic chain free.15 Therefore,
of the oxygens of the counter ion and one of the aromatic the aliphatic chain adopted a folded conformation tilted
protons of the macrocyclic ligand has been observed, O(4)⋯H towards the coordinated phenanthroline unit and away from
(9)–C(9): 2.550 Å, see Fig. S1.† As expected, the coordination the metal centre, leaving the correspondent axial ligand (either
sphere of each rhenium(I) metal is a distorted octahedron, where chloride, imidazole or pyridine) in the furthermost position in
the three carbonyls are arranged in a facial disposition. For all each case. Such a disposition promoted a severe distortion for
the complexes the equatorial plane is defined by the chelated the phenanthroline unit in the rhenium coordination sphere.
phenanthroline unit and two trans carbonyls. The third carbo- In all cases, the phenanthroline plane is largely tilted from the
nyl is placed in the axial position, trans to the corresponding rhenium coordination plane defined by the two phenanthro-
ligand: (a) a chloride atom (compound 2), (b) an imidazole line nitrogen atoms and the correspondent trans carbon atoms
Fig. 2 Molecular structure of complex 2 and complex cations in 5, 6, 7 and 8’ respectively. The most relevant bond lengths (Å) and angles (°): complex
2: Re(1)–C(1) = 1.903(3), Re(1)–C(2) = 1.903(3), Re(1)–C(3) = 1.912(3), Re(1)–N(1) = 2.206(3), Re(1)–N(2) = 2.237(3), Re(1)–Cl(1) = 2.4963(10); N(1)–Re(1)–
N(2) = 74.01(10), Cl(1)–Re(1)–C(2) = 174.85(9); complex 5: Re(1)–C(1) = 1.915(4), Re(1)–C(2) = 1.905(3), Re(1)–C(3) = 1.925(4), Re(1)–N(1) = 2.187(3),
Re(1)–N(3) = 2.214(3), Re(1)–N(4) = 2.195(3); N(4)–Re(1)–N(3) = 74.35(10), C(1)–Re(1)–N(1) = 177.04(12); Complex 6: Re(1)–C(1) = 1.935(13), Re(1)–C(2) =
1.943(12), Re(1)–C(3) = 1.924(13), Re(1)–N(1) = 2.209(10), Re(1)–N(2) = 2.219(9), Re(1)–N(3) = 2.206(9); N(3)–Re(1)–N(2) = 74.9(3), C(1)–Re(1)–N(1) =
177.6(4); complex 7: Re(1)–C(1) = 1.924(4), Re(1)–C(2) = 1.920(2), Re(1)–C(3) = 1.913(4), Re(1)–N(1) = 2.204(3), Re(1)–N(2) = 2.199(3), Re(1)–N(3) =
2.1803(19); N(2)–Re(1)–N(1) = 74.62(10), C(2)–Re(1)–N(3) = 177.61(12); Complex 8’: Re(1)–C(1) = 1.919(5), Re(1)–C(2) = 1.920(5), Re(1)–C(3) = 1.899(4),
Re(1)–N(1) = 2.215(4), Re(1)–N(2) = 2.220(4), Re(1)–N(3) = 2.209(3); N(3)–Re(1)–N(2) = 74.58(13), C(2)–Re(1)–N(1) = 174.74(14).
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of the carbonyl groups. The dihedral angle between the equa- either a dimer or a polymeric chain respectively. In complex
torial plane previously defined with that containing the 11, where the coordinated macrocyclic ligand L1 contains
phenanthroline unit varies from 33.8° to 35.1°. Such deviation three S-donor atoms in the aliphatic portion, the silver(I) atom
from the ideal coplanar disposition is much larger than those is coordinated to the central S-donor of one macrocyclic unit
found in the literature for analogous 2,9-dimethyl-1,10- and to the S-donor at the end of the aliphatic chain of a
phenanthroline rhenium(I) derivatives (from 7.3° to 25.9°) and second macrocyclic unit from the symmetry related Re(I)
it might be ascribed to the higher steric requirement of the complex units of 6 forming dimers (Fig. 2 and 3). Instead, in
thioether or mixed thio/oxo ether crown in comparison with complex 12, where the coordinated macrocyclic ligand L2 con-
the methyl derivative.16
tains two S-donor atoms and one O-donor in the aliphatic
X-ray diffraction for complexes 11 and 12 was also recorded, portion, the silver(I) atom binds to the S-atoms of two adjacent
Fig. 3. Crystals were small and diffracted weakly. Furthermore, molecule units from the symmetry related Re(I) complex units
in both complexes there were some disorder problems. Com- of fac-[Re(CO)3(Py)(L2)]+, originating polymeric chains (Fig. 3).
pound 11 crystallised as a dimer but only half of the molecule In both cases, bond distances for Ag(I)–S range from 2.473(4) Å
is in the asymmetric unit, where there are one and two halves to 2.656(5) Å, which is in agreement with bond distance
trifluoromethanesulfonate disordered molecules. Complex values for similar complexes found in the literature.14b In
12 crystallised as an infinite polymeric chain, where one of the addition, complex 11 showed a molecule of triflate coordinated
S–C bonds in the macrocycle is disordered over two positions. to the silver(I) atom, arranging the donor atoms in a trigonal
Both of them present similar bond length and angle values in disposition around the metal centre. In the case of complex
the rhenium(I) environment to those seen in compounds 2, 5, 12, the silver atom acting as a linker is also coordinated to a
6, 7 and 8′. Re–CO bond distances range between 1.874(10) Å triflate molecule and an acetone molecule from the crystallisa-
and 1.940(11) Å, Re–N(py) bond distances are 2.212(10) Å and tion solvent mixture, providing a distorted tetrahedral environ-
2.225(8) Å and chelate angles of N(phen)–Re–N(phen) are ment around the metal centre, S1–Ag1–S2#2 129.30(14)°
74.2(4)° and 75.4(3)°, respectively. Moreover they also display instead of the ideal 109.4°.
deviation of the phenanthroline unit from the Re(I) equatorial
plane defined by the two phenanthroline nitrogen atoms and
Photophysical studies
the corresponding trans carbon atoms of the carbonyl groups, UV-visible absorption spectra, recorded in a degassed dichloro-
affording dihedral angles of 32.5° (complex 11) and 33.9° methane or acetone solution at 298 K, showed the typical
(complex 12). These values are slightly smaller than the di- pattern for diimine Re(I) derivatives (Fig. 4 and S2†). Ligand
hedral values observed for their precursors, i.e. 32.9 for centred transitions, π → π* transitions among L1, L2, imida-
complex 6 and 34.9° in the case of complex 8′. The main differ- zole and pyridine units, were observed at higher energies, and
ence between these two molecular structures relies on the metal-to-ligand-charge-transfer transitions (1MLCT), formally
coordination site preferred by the silver(I) atom of the macro- attributed to Re(dπ) → L(π*) transitions appeared at lower ener-
cycle ligands, which ultimately promotes the formation of gies around 400 nm, with a tail extending in some cases up to
Fig. 3 Molecular structure of dimeric and polymeric assemblies in compounds 11 and 12. The most relevant bond lengths (Å) and angles (°):
complex 11: Re(1)–C(1) = 1.921(15), Re(1)–C(2) = 1.906(13), Re(1)–C(3) = 1.918(17), Re(1)–N(1) = 2.214(12), Re(1)–N(2) = 2.215(10), Re(1)–N(3) = 2.214
(13), Ag(1)–O(4) = 2.365(18), Ag(1)–S(2) = 2.470(4), Ag(1)–S(1) = 2.522(4); N(2)–Re(1)–N(3) = 74.2(4), C(1)–Re(1)–N(2) = 169.9(5), O(4)–Ag(1)–S(2) =
106.4(5), O(4)–Ag(1)–S(1) = 86.3(5), S(1)–Ag(1)–S(2) = 148.81(14); complex 12: Re(1)–C(1) = 1.940(11), Re(1)–C(2) = 1.874(10), Re(1)–C(3) = 1.893(12),
Re(1)–N(1) = 2.225(8), Re(1)–N(2) = 2.212(10), Re(1)–N(3) = 2.215(9), Ag(1)–S(2) = 2.656(5), Ag(1)–S(1) = 2.502(3); N(2)–Re(1)–N(3) = 75.4(3), C(2)–Re
(1)–N(1) = 176.7(4), S(1)–Ag(1)–S(2)#2 = 129.30(14) (#2 = x, −y, z + 1/2).
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Fig. 4 UV-absorption spectra of complexes
degassed dichloromethane at 298 K.
1 and 2 recorded in
Fig. 5 Emission spectra of complexes 6 and 11 recorded in degassed
dichloromethane at 298 K.
be reasonable to think that such a distortion could be favour-
ing the destabilisation of the HOMO orbitals, mainly Re(dπ)
orbitals, in comparison with the analogue phenanthroline
species. In addition, it could also be suggested that the pres-
ence of thioether or mixed thio/oxoether crown systems grafted
on the phenanthroline might exert, to some extent, an induc-
tive effect as no conjugation in the system is present. There-
fore, reduction of the energy gap between the HOMO and
LUMO orbitals would take place. Furthermore, the mixed S/O-
donor ligand L2 seems to greatly affect the emissive properties
as compared to L1, possibly because of the higher electro-
negativity of the oxygen atom. As expected, the emission
maxima of cationic species in 5–8 experienced a shift of
ca. 30 nm to lower energy in comparison with their neutral
precursors, species 1 and 2. Additionally, a slightly red shifted
emission maximum was observed for the heterometallic com-
plexes 9 and 10 when compared with their respective pre-
cursors, complexes 5 and 7. Such behaviour contrasted with
that of the heterometallic complexes 11 and 12 whose emis-
sion maxima shifted drastically from ca. 573 nm to 540 nm
and from 595 nm to 560 nm, respectively, when compared to
that of their monometallic analogues, complexes 6 and 8. It
might be reasonable to suggest that the coordination of the
second metallic fragment to the heteroatoms of the crown
system might influence the emissive properties to a higher
degree than when the coordination is performed in the axial
imidazole ligand (complexes 9 and 10), which is in line with
the idea that the molecular orbitals involved in the emissive
process are mainly those centred in the phenanthroline
unit.3,17 The blue shifted emissions observed for complexes 11
and 12 could be partially explained in terms of either the
stabilisation of HOMO orbitals and/or destabilisation of
LUMO orbitals. The fact that the silver atom is coordinated
with different positions of the crown system, i.e. to S(15) for
complex 11 and to S(12) and S(18) for complex 12, might indi-
cate that the blue shift would be strongly related to changes in
the metal based orbitals rather than in the ligand. Therefore, a
possible explanation could be that, somehow, the coordination
of the second metallic fragment led to less constricted species
475 nm. The most significant absorption data together with
the emission and excitation maxima values for all complexes
are collected in Table 2.
Luminescence spectra of complexes 1, 2, 5–12 were
recorded in degassed dichloromethane solution at 298 K
(Fig. 5 and S3†). All of them showed a broad emission between
573–633 nm originated from the 3MLCT Re(dπ) → phen(π*)
excited state, which has been previously reported in many
rhenium(I) diimine tricarbonyl complexes.17
The neutral complexes 1 and 2 showed their emission
maxima at 608 nm and 633 nm, respectively. Comparison with
the emission maxima seen for the analogous phenanthroline
derivative, [ReCl(CO)3(2,9-dimethyl-1,10-phenanthroline)], that
appears at 578 nm in the dimethyl sulfoxide solution or
589 nm in dimethylformamide, revealed the high influence of
the aliphatic chain of the coordinated macrocyclic ligands on
the photophysical properties18 The constriction observed for
the phenanthroline unit, which is tilted towards itself and
away from the metal centre, might be implicated in the
observed red shift for the complexes described here. It would
Table 2 Absorption bands, excitation and emission maxima values
(298 K)
UV-vis (×104 3/dm3 mol−1 cm−1
)
λexc (nm)
λem (nm)
1a
2a
5a
6a
7a
272 (13 900), 332 (8000), 416 (1600)
279(30 700), 329(23 200), 402(5000)
250(24 000), 331(14 400), 406 (2600)
257 (21 600), 330(11 700), 400(2600)
230(32 500), 235(32 000), 253(23 400),
275(19 000), 329(16 300), 403(3500)
236(28 000), 256(26 700), 283(19 000),
329(16 100), 394 (3700)
448
440
410
400
430
608
633
586
573
608
8a
420
595
9a
336(3900), 408 (1200)
444
456
400a
339
600
612
540a
560
10a
11a/b
12a
290(8100), 331(8100), 414(1600)
326(3900), 401(2800)b
259(25 400), 287(19 900),
334(9700), 403(2000)
a Degassed dichloromethane. b Degassed acetone.
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promoting the stabilisation of the HOMO orbitals, and conse- Crystal structure determinations
quently a blue shifted emission.
Crystals were mounted in inert oil on glass fibers and trans-
ferred to the cold gas stream of an Xcalibur Oxford Diffraction
diffractometer equipped with a low-temperature attachment.
Data were collected using monochromated MoKα radiation
(λ = 0.71073 Å). Scan type ω. Absorption corrections based on
multiple scans were applied using spherical harmonics
implemented in the SCALE3 ABSPACK scaling algorithm. The
structures were solved by direct methods and refined on
F2 using the program SHELXL-97.19 All non-hydrogen atoms
were refined anisotropically, with the exception of complex 7.
Further details on the crystal refinements are shown in
Table 3. Special constraints to all the bond distances and
angles to the disordered triflate molecules in complexes
11 and 12 have been applied.
Conclusions
In summary, we have synthesised and characterized a new
family of luminescent fac-[Re(CO)3(L)(NN)]+ complexes, where
L is a pyridine (py) or an imidazole (ImH) ligand, and NN are
macrocyclic ligands featuring a 1,10-phenanthroline subunit
functionalised at the 2,9-positions with either a thioether (L1)
or a mixed thio-oxoether linker (L2). Moreover, we have pre-
pared the corresponding heterometallic species Re(I)/Au(I) and
Re(I)/Ag(I), specifically fac-[Re(CO)3(L1)(ImAu(PPh3))](CF3SO3)
(9), fac-[Re(CO)3(L2)(ImAu(PPh3))](CF3SO3) (10), fac-[Re(CO)3-
(L1)(Py)Ag](CF3SO3)2 (11) and fac-[Re(CO)3(L2)(Py)Ag](CF3SO3)2
(12). Structural characterization by X-ray diffraction studies
showed the expected octahedral disposition around the Re(I)
Materials and procedures
metal centre with the aliphatic chains of the macrocyclic The starting material [AuCl(PPh3)] was prepared according to
ligands adopting a folded conformation tilted towards the literature procedures.20 [Au(CF3SO3)(PPh3)] was prepared
phenanthroline unit and away from the metal centre, leaving in situ by reaction of [AuCl(PPh3)] with Ag(CF3SO3) in dichloro-
the corresponding axial ligand in the furthermost position. methane.20 All other starting materials and solvents were pur-
Complexes 11 and 12 displayed coordination of the silver(I) chased from commercial suppliers and used as received unless
centre to the sulfur atoms of the coordinated macrocyclic otherwise stated.
ligands, giving two different structural motifs, a dinuclear
Synthesis of fac-[Re(Cl)(CO)3(L1)] (1). [ReCl(CO)5] (111 mg,
compound (11) with two fac-[Re(CO)3(Py)(L1)]+ metalloligands 0.30 mmol) and L1 (112 mg, 0.31 mmol) were heated at reflux
bridged by two Ag(I) centres and a polynuclear chain (12) with in dry toluene (10 ml) under a nitrogen atmosphere for 1 h.
the silver(I) atom bonded to one sulfur of the adjacent fac-[Re The solvent was removed to dryness and the yellow solid was
(CO)3(Py)(L2)]+ metalloligands. Photophysical analysis showed washed with hexane and ether. Finally, the product was puri-
the typical behavior for Re(I) complexes, i.e. emission from a fied by chromatography (silica, dichloromethane/acetone (9.5/
3MLCT transition at around 600 nm, being those of the hetero- 0.5)) (147 mg, 72% yield). 1H NMR (dichloromethane-d6,
metallic complexes 11 and 12 blue shifted in comparison with 400 MHz): δH 8.49 (d, J = 8.4 Hz, 2H, CH(3, 8)), 7.97 (d, J =
their monometallic analogues. These results, contrary to pre- 8.4 Hz, 2H, CH(4, 7)), 7,95 (s, 2H, CH(5, 6)), 4.92 (d, J = 14.0
vious reports published on similar crown phenanthroline Re(I) Hz, 2H, CH2(11a, 19a or 11b, 19b)), 4.39 (d, J = 14.0 Hz, 2H,
derivatives,5 emphasize the importance of the phenanthroline- CH2(11a, 19a or 11b, 19b)), 3.08–2.91 (m, 2H, CH2(13a, 17a or
based ligand design in order to obtain the specific emission 13b, 17b)), 2.28–2.15 (m, 4H, CH2 (13a, 17a or 13b, 17b and
properties of the resulting systems.
14a, 16a or 14b, 16b)), 1.84–1.57 (m, 2H, CH2(14a, 16a or 14b,
16b)). 13C NMR (dichloromethane-d6, 101 MHz): δC 195.7
(CO), 165.7 (C(2, 9)), 148.4 (C(4b, 6b)), 139.6 (C(3, 8)), 129.4
(C(4a, 6a)), 126.6 (C(5, 6)), 125.7 (C(4, 7)), 34.8 (C(11, 19)), 33.3
(C(14, 16)), 30.2 (C(13, 17)). MS (MALDI+): m/z 629.1 ([M − Cl]+
100%) calculated: 629.0; IR (solid, cm−1, (CO)): 2012, 1884;
Experimental section
General measurements and analysis instrumentation
Mass spectra were recorded on a BRUKER ESQUIRE 3000 Anal. calc. for ReC21H18ClN2O3S3: C, 37.97; H, 2.73; N, 4.22.
PLUS, with the electrospray (ESI) technique and on a BRUKER Found: C, 38.04; H, 2.75; N, 4.15.
(MALDI-TOF). 1H, 13C{1H} and 31P{1H} NMR, including 2D
Synthesis of fac-[Re(Cl)(CO)3(L2)] (2). This compound was
experiments, were recorded at room temperature on a BRUKER prepared similarly to fac-[ReCl(CO)3(L1)] using L2 instead of L1
AVANCE 400 spectrometer (1H, 400 MHz, 13C, 100.6 MHz, and purification by chromatography was not needed. The
1
31P, 162 MHz) with chemical shifts (δ, ppm) reported relative product obtained was a yellow solid (240 mg, 98%). H NMR
to the solvent peaks of the deuterated solvent. Infrared spectra (400 MHz, (dichloromethane-d6)) δ 8.48 (d, J = 8.4 Hz, 2H,
were recorded in the range 4000–250 cm−1 on a Perkin-Elmer CH(3, 8)), 7.94 (s, 2H, CH(5, 6)), 7.87 (d, J = 8.4 Hz, 2H,
Spectrum 100 FTIR spectrometer. Room temperature steady- CH(4, 7)), 4.77 (d, J = 14.0 Hz, 2H, CH2(11a, 19a or 11b, 19b)),
state emission and excitation spectra were recorded with a 4.41 (d, J = 14.1 Hz, 2H, CH2(11a, 19a or 11b, 19b)), 3.16–3.01
Jobin–Yvon–Horiba fluorolog FL3-11 spectrometer fitted with a (m, 4H, CH2(14, 16)), 2.41–2.27 (m, 4H, CH2(13, 17)). 13C NMR
JY TBX picosecond detection module. UV/vis spectra were (101 MHz, CD2Cl2), δC 197.5 (CO), 195.4 (CO), 166.0 (C(2, 9)),
recorded with a 1 cm quartz cells on an Evolution 600 148.7 (C(4b, 6b)), 139.6 (C(3, 8)), 129.3 (C(4a, 6a)), 126.7 (C(5,
spectrophotometer.
6)), 125.5 (C(4, 7)), 71.6 (C(14, 16)), 43.8 (C(11, 19)), 31.9 (C(13,
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17)), MS (ESI) m/z 612.8 [M − Cl] calculated 612.4; IR (solid,
Synthesis of fac-[Re(CO)3(L1)(Py)](CF3SO3) (6). A solution of
cm−1
,
(CO)): 2017, 1910, 1882; Anal. calc. for fac-[Re((CH3)2CO)(CO)3(L1)](CF3SO3) (31 mg, 0.03 mmol) and
ReC21H18ClN2O4S2: C, 38.91; H, 2.80; N, 4.32. Found: C, 38.78; pyridine (23 μl, 0.3 mmol) in acetone (5 ml) were stirred for
H, 2.75; N, 4.17. 4 days at room temperature under an argon atmosphere. Then,
Synthesis of fac-[Re((CH3)2CO)(CO)3(L1)](CF3SO3) (3). fac- hexane was added affording the precipitation of a yellow solid
fac-[Re(Cl)(CO)3(L1)] (17 mg, 0.02 mmol) and silver triflate which was further washed with ether and hexane (26 mg,
1
(6.5 mg, 0.02 mmol) were stirred in 5 ml of acetone for 12 h, 80%). H NMR (400 MHz, acetone-d6) δ 8.88 (d, J = 8.5 Hz, 2H,
then the mixture was filtered through Celite to eliminate the CH(3, 8), L1), 8.44 (d, J = 8.5 Hz, 2H, CH(4, 7), L1), 8.07 (s, 2H,
silver chloride formed during the reaction. Finally, the solvent CH(5, 6), L1), 7.82–7.73 (m, 3H, CH(2, 4, 6), Py), 7.16–7.09 (m,
was removed under vacuum affording a yellow solid (20 mg, 2H, CH(3, 5), Py), 4.97 (d, J = 13.9 Hz, 2H, CH2(11a, 19a or 11b,
83% yield). 1H NMR (400 MHz, acetone-d6) δ 9.04 (d, J = 19b)), 4.90 (d, J = 13.9 Hz, 2H, CH2(11a, 19a or 11b, 19b)), 3.03
8.4 Hz, 2H, CH(3, 8)), 8.47–8.37 (m, 4H, CH(4, 7)), 4.96 (dd, J = (ddd, J = 14.3, 13.2, 4.9 Hz, 2H, CH2(13a, 17a or 13b, 17b)),
34.6, 14.6 Hz, 4H, CH2(11, 19)), 3.35–3.28 (m, 2H), 3.18–3.10 2.47–2.34 (m, 2H, CH2(13a, 17a or 13b, 17b)), 2.32–2.18 (m,
(m, 2H), 2.97–2.87 (m, 4H), 2.09 (s, 6H, CH3). MS (MALDI+): 2H, CH2(14a, 16a or 14b, 16b)), 1.63 (td, J = 13.5, 5.0 Hz, 2H,
m/z 629.1 ([M
−
((CH3)2CO)]+ 100%) calculated: 629.0; CH2(14a, 16a or 14b, 16b)). 13C NMR (101 MHz, acetone-d6):
δC 169.8 (C(2, 9), L1), 153.6 (C(2, 6), Py), 147.1 (C(4b, 6b), L1),
IR (solid, cm−1, (CO)): 2031, 1932, 1904.
Synthesis of fac-[Re((CH3)2CO)(CO)3(L2)](CF3SO3) (4). This 142.5 (C(3, 8), L1), 142.2 (C(4), Py), 131.3 (C(4a, 6a), L1), 129.6
compound was prepared similarly to fac-[Re((CH3)2CO)(CO)3(L1)]- (C(5, 6), L1), 128.9 (C(4, 7), L1), 128.3 (C(3, 5), Py), 45.1 (C(11,
(CF3SO3) using fac-[ReCl(CO)3(L2)] instead of fac-[ReCl- 19), L1), 36.1 (C(14, 16, L1), 34.7 (C(13, 17), L1); MS (MALDI+):
(CO)3(L1)]. The product obtained was a yellow solid (80%). m/z 629.1 ([M − Py]+ 76.21%) calculated: 629.0, m/z 708.1 ([M]+
1H NMR (400 MHz, acetone-d6) δ 8.99 (d, J = 8.4 Hz, 2H, CH(3, 19.56%) calculated 707.3; IR (solid, cm−1, (CO)): 2029, 1932,
8)), 8.42 (d, J = 8.4 Hz, 2H CH(4, 7)), 8.32 (s, 2H, CH(5, 6)), 5.33 1914; Anal. calc. for ReC27H23F3N3O6S4: C, 37.84; H, 2.71;
(d, J = 16.0 Hz, 2H, CH2(11a, 19a or 11b, 19b)), 5.09 (d, J = N, 4.90. Found: C, 37.98; H, 2.73; N, 4.82.
16.0 Hz, 2H, CH2(11a, 19a or 11b, 19b)), 3.95–3.87 (m, 2H,
Synthesis of fac-[Re(CO)3(ImH)(L2)](CF3SO3) (7). This com-
CH2(14a, 16a or 14b, 16b)), 3.49 (ddd, J = 10.8, 5.5, 2.3 Hz, 2H, pound was prepared similarly to fac-[Re(CO)3ImH(L1)](CF3SO3)
CH2(14a, 16a or 14b, 16b)), 3.10 (dd, J = 13.9, 4.4 Hz, 2H, using fac-[Re((CH3)2CO)(CO)3(L2)](CF3SO3) instead of fac-
CH2(13a, 17a or 13b, 17b)), 2.41–2.30 (m, 2H, CH2(13a, 17a or [Re((CH3)2CO)(CO)3(L1)](CF3SO3). The product obtained was a
13b, 17b)), 2.09 (s, 6H, CH3).13C NMR (101 MHz, acetone-d6) yellow solid (31 mg, 62%). 1H NMR (400 MHz, acetone-d6)
δ 165.1 (C(2, 9)), 148.8 (C(4b, 6b)), 141.1 (C(3, 8)), 130.3 (C(4a, δ 11.87 (s, NH), 8.84 (d, J = 8.5 Hz, 2H, CH(3, 8); L2), 8.28 (d,
6a)), 127.9 (C(5, 6)), 125.9 (C(4, 7)), 72.5 (C(14, 16), 49.3 (C(11, J = 8.5 Hz, 2H, CH(4, 7); L2), 8.08 (s, 2H, CH(5, 6), L2), 7.28 (s,
19)), 34.3 (C(13, 17)), 30.6 (2CH3); IR (solid, cm−1, (CO)): 2033, 1H, CH(2), IMH), 6.80 (s, 1H, CH(4), ImH), 6.09 (s, 1H, CH(5),
1932, 1903.
ImH), 4.92 (d, J = 14.0 Hz, 2H, CH2(11a, 19a or 11b, 19b)), 4.74
Synthesis of fac-[Re(CO)3(ImH)(L1)](CF3SO3) (5). A solution (d, J = 14.0 Hz, 2H, CH2(11a, 19a or 11b, 19b)), 3.49–2.47 (m,
of fac-[Re((CH3)2CO)(CO)3(L1)](CF3SO3) (31 mg, 0.04 mmol) 4H, CH2(14, 16)), 2.52–2.44 (m, 2H, CH2(13a, 17a or 13b, 17b)),
and imidazole (27 mg, 0.4 mmol) in dry THF (3 ml) were 2.31–2.25 (m, 2H, CH2(13a, 17a or 13b, 17b)); 13C NMR
stirred for 24 h at room temperature under an argon atmos- (101 MHz, acetone-d6), δC 196.9 (CO), 195.5 (CO), 169.7 (C(2,
phere. Then, the solvent was removed under vacuum and the 9) L2), 147.8 (C(4b, 6b), L2), 142.1 (C(3, 8), L2), 139.9 (C(2),
residue was triturated with ether and hexane affording ImH), 131.0 (C(4a, 6a), L2), 130.1 (C(5), ImH), 128.7 (C(5, 6),
complex 5 as yellow solid (21 mg, 72%). 1H NMR (400 MHz, L2), 128.5 (C(4, 7), L2), 127.1 (C(4), ImH), 72.7 (C(14, 16), L2),
acetone-d6) δ 8.86 (d, J = 8.5 Hz, 2H, CH(3, 8), L1), 8.36 (d, J = 45.3 (C(11, 19), L2), 33.3 (C(13, 17), L2); MS (MALDI+): m/z
8.5 Hz, 2H, CH(4, 7), L1), 8.10 (s, 2H, CH(5, 6), L1), 7.33 (t, J = 613.0 ([M − ImH]+ 100%) calculated: 613.1, m/z 681.1 ([M]+
1.2 Hz, 1H, CH(2) ImH), 6.85–6.80 (m, 1H, CH(4) ImH), 6.12 (t, 7.82%) calculated 681.1; IR (solid, cm−1, (CO)): 2033, 1937,
J = 1.4 Hz, 1H, CH(5) ImH), 4.91 (s, 4H, CH(11, 19)), 3.03 (ddd, 1920; Anal. calc. for ReC25H22F3N4O7S3: C, 36.18; H, 2.67;
J = 14.3, 13.2, 4.9 Hz, 2H, CH2(13a, 17a or 13b, 17b)), 2.43–2.30 N, 6.75. Found: C, 35.87; H, 2.78; N, 6.58.
(m, 2H, CH2(13a, 17a or 13b, 17b)), 2.22 (td, J = 13.3, 4.1 Hz,
Synthesis of fac-[Re(CO)3(L2)(Py)](CF3SO3) (8). This com-
2H, CH2(14a, 16a or 14b, 16b)), 1.61 (td, J = 13.5, 4.9 Hz, 2H, pound was prepared similarly to fac-[Re(CO)3ImH(L2)](CF3SO3)
CH2(14a, 16a or 14b, 16b)). 13C NMR (101 MHz, acetone-d6): using pyridine instead of imidazole. The product obtained was
δC 197.0 (CO), 195.4 (CO), 169.4 (C(2, 9), L1), 147.5 (C(4b, 6b), a yellow solid (81 mg, 74%). 1H NMR (400 MHz, acetone-d6)
L1), 142.2 (C(3, 8), L1), 140.7 (C(2), ImH), 131.1 (C(4a, 6a), L1), δ 8.86 (d, J = 8.5 Hz, 2H, CH(3, 8), L2)), 8.36 (d, J = 8.5 Hz, 2H,
130.1(C(5), ImH), 128.9 (C(5, 6), L1), 128.8 (C(4, 7), L1), 120.3 CH(4, 7), L2), 8.05 (s, 2H, CH(5, 6), L2), 7.82–7.69 (m, 3H,
(C(4), ImH), 44.9 (C(11, 19), L1), 36.1 (C(14, 16, L1), 34.6 (C(13, CH(2, 4, 6), Py), 7.11 (ddd, J = 7.2, 4.6, 1.7 Hz, 2H, CH(3, 5),
17, L1); MS (MALDI+): m/z 629.1 ([M
−
ImH]+ 34.6%) Py), 4.99 (d, J = 14.1 Hz, 2H, CH2(11a, 19a or 11b, 19b)), 4.73
calculated: 629.0, m/z 697.1 ([M]+ 3.81%) calculated: 696.0; (d, J = 14.1 Hz, 2H, CH2(11a, 19a or 11b, 19b)), 3.19–3.03 (m,
IR (solid, cm−1, (CO)): 2024, 1909, 1887; Anal. calc. for 4H, CH2(14, 16)), 2.56–2.49 (m, 2H, CH2(13a, 17a or 13b, 17b)),
ReC25H22F3N4O6S4: C, 35.50; H, 2.62; N, 6.62. Found: C, 35.86; 2.29–2.23 (m, 2H, CH2(13a, 17a or 13b, 17b)); 13C (101 MHz,
H, 2.73; N, 6.45.
acetone-d6), δC 196.3 (CO), 195.2 (CO), 170.2 (C(2, 9) L2), 153.7
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(C(2, 6) Py), 147.3 (C(4b, 6b) L2), 142.4 (C(8, 3) L2), 142.0 (C(4) calc. for ReAuC43H36F3N4O7PS3: C, 40.09; H, 2.82; N, 4.35.
Py), 131.2 (C(4a, 6a) L2), 129.5 (C(5, 6) L2), 128.7 (C(4, 7) L2), Found: C, 39.88; H, 2.87; N, 4.23.
128.2(C(3, 5) Py), 72.6 (C(14, 16) L2), 45.3 (C(11, 19) L2), 33.4
Synthesis of fac-[Re(CO)3(L1)(Py)Ag](CF3SO3)2 (11). To a
(C(13, 17) L2). MS (MALDI+): m/z 613.1 ([M − Py]+ 100%) calcu- solution of fac-[Re(CO)3(L1)Py](CF3SO3) (17 mg, 0.02 mmol in
lated: 613.1, m/z 692.2 ([M]+ 2.38%) calculated 692.1; IR (solid, acetone (5 ml) was added dropwise an acetone solution of
cm−1
,
(CO)): 2028, 1936, 1904; Anal. calc. for AgCF3SO3 (5.1 mg, 0.02 mmol) and it was kept stirring at room
ReC27H23F3N3O7S3: C, 38.57; H, 2.76; N, 5.00. Found: C, 38.91; temperature under an argon atmosphere for 3 days. Then,
H, 2.63; N, 5.15. hexane was added and the desired product precipitated as a
1
Synthesis of fac-[Re(CO)3(ImAu(PPh3))(L1)](CF3SO3) (9). To yellow solid. (17 mg, 79% yield). H NMR (400 MHz, acetone-
mixture of fac-[Re(CO)3ImH(L1)](CF3SO3) (12.5 mg, d6) δ 8.89 (d, J = 8.5 Hz, 2H, CH(3, 8), L1), 8.46 (d, J = 8.5 Hz,
a
0.018 mmol) and [Au(CF3SO3)(PPh3)]17 (22 mg, 0.035 mmol) in 2H, CH(4, 7), L1), 8.06 (s, 2H, CH(5, 6), L1), 7.76 (td, J = 6.2,
dry dichloromethane (5 ml) was added Cs2(CO)3 (17.6 mg, 2.1 Hz, 3H, CH(2, 4, 6), Py), 7.16–7.08 (m, 2H, CH(3, 5), Py),
0.05 mmol). The suspension was stirred at room temperature 5.02 (d, J = 14.0 Hz, 2H, CH2(11a, 19a or 11b, 19b)), 4.93 (d, J =
under an argon atmosphere for 2 hours. Then, the mixture was 14.1 Hz, 2H, CH2(11a, 19a or 11b, 19b)), 3.15–3.02 (m, 2H,
filtered through Celite and the solvent was removed under CH2(13a, 17a or 13b, 17b)), 2.55–2.45 (m, 2H, CH2(13a, 17a or
vacuum affording a beige solid which was further washed with 13b, 17b)) 2.40 (td, J = 13.4, 4.1 Hz, 2H, CH2(14a, 16a or 14b,
ether and hexane. (10 mg, 54% yield). 1H NMR (400 MHz, 16b)), 1.80 (td, J = 13.4, 5.0 Hz, 2H, CH2(14a, 16a or 14b,
acetone-d6) δ 8.84 (d, J = 8.5 Hz, 2H, CH(3, 8); L1), 8.35 (d, J = 16b)).13C-NMR (101 MHz, acetone-d6): δC 169.6 (C(2, 9), L1),
8.5 Hz, 2H, CH(4, 7), L1), 8.07 (s, 2H, CH(5, 6), L1), 7.78–7.46 153.6 (C(2, 6), Py), 147.2 (C(4b, 6b), L1), 142.6 (C(3, 8), L1),
(m, 15H, Ph), 6.86 (s, 1H CH(2), Im), 6.59 (s, 1H, CH(4), Im), 142.2 (C(4), Py), 131.4 (C(4a, 6a), L1), 129.6 (C(5, 6), L1), 128.9
5.97 (d, J = 1.2 Hz, 1H, CH(5), Im), 4.91 (q, J = 13.9 Hz, 4H, (C(4, 7), L1), 128.3 (C(3, 5), Py), 45.1 (C(11, 19), L1), 36.5, 34.7
CH2(11, 19)), 3.08–2.98 (m, 2H, CH2(14a, 16a or 14b, 16b)), (SCH2CH2S). MS (MALDI+): m/z 847.3 ([M
−
CF3SO3
+
−
2.39–2.30 (m, 4H, CH2(13a, 17a or 13b, 17b and 14a, 16a or CH3OH]+, 0.13%) calculated 847.0, m/z 708.3 ([M
14b, 16b)), 1.61 (td, J = 13.5, 5.0 Hz, 2H, CH2(14a, 16a or 14b, AgCF3SO3]+, 0.15%) calculated 708.0, m/z 629.3 ([M − Py −
16b)); 31P NMR (162 MHz, acetone-d6): δP 31.7. MS AgCF3SO3]+, 47.7%) calculated 629.0; IR (solid, cm−1, (CO)):
(MALDI+): m/z 1155.2 ([M]+, 100%) calculated: 1155.1, m/z 2031, 1932, 1918.
629.0 ([M − Im − Au(PPh)3]+, 61%) calculated 629.0; IR (solid,
Synthesis of fac-[Re(CO)3(L2)(Py)Ag](CF3SO3)2 (12). To a
cm−1, (CO)): 2023, 1932, 1882; Anal. calc. for ReAuC43H36F3- solution of fac-[Re(CO)3Py(L2)](CF3SO3) (25 mg, 0.029 mmol)
N4O6PS4: C, 39.60; H, 2.78; N, 4.30. Found: C, 39.37; H, 2.83; in acetone (5 ml) was added dropwise an acetone solution of
N, 4.45.
Synthesis
AgCF3SO3 (8 mg, 0.031 mmol) and it was kept stirring at room
fac-[Re(CO)3(ImAu(PPh3))(L2)](CF3SO3) temperature under an argon atmosphere for 24 h. Then,
of
(10). fac-[Re(CO)3ImH(L2)](CF3SO3) (20 mg, 0.024 mmol) hexane was added and the desired product precipitated as a
1
Cs2(CO)3 (29 mg, 0.089 mmol) and [Au(CF3SO3)(PPh3)]17 yellow solid. (20 mg, 61% yield). H NMR (400 MHz, acetone-
(59 mg, 0.97 mmol) in dry dichloromethane (5 ml) were stirred d6) δ 8.90 (d, J = 8.5 Hz, 2H, CH(3, 8), L2)), 8.44 (d, J = 8.5 Hz,
for 1 h at room temperature. Then, the mixture was filtered 2H, CH(4, 7), L2), 8.07 (s, 2H, CH(5, 6), L2), 7.83–7.71 (m, 3H,
through Celite and ether was added affording the precipitation CH(2, 4, 6), Py), 7.10 (dd, 2H, J = 7.5, 6.7 Hz, CH(3, 5), Py), 5.19
of the desired product as a light brown solid which was further (d, J = 14.1 Hz, 2H, CH2(11a, 19a or 11b, 19b)), 4.85 (d, J = 14.1
washed with ether (9 mg, 27% yield). 1H NMR (400 MHz, Hz, 2H, CH2(11a, 19a or 11b, 19b)), 3.33–3.25 (m, 2H, CH2(13a,
acetone-d6) δ 8.82 (d, J = 8.5 Hz, 2H, CH(3, 8), L2)), 8.27 (d, J = 17a or 13b, 17b)), 3.13 (td, J = 10.2, 5.6 Hz, 2H, CH2(14a, 16a or
8.5 Hz, 2H, CH(4, 7), L2), 8.06 (s, 2H, CH(5, 6) L2), 7.73–7.46 14b, 16b)), 2.72–2.64 (m, 2H, CH2(13a, 17a or 13b, 17b)), 2.28
(m, 15H, Ph), 6.84 (s, 1H, CH(2), Im), 6.58 (s, 1H(4), Im), 5.95 (td, J = 10.4, 4.6 Hz, 2H, CH2(14a, 16a or 14b, 16b)).
(d, J = 1.2 Hz, 1H, 1H(5), Im), 4.90 (d, J = 14.0 Hz, 2H, CH2(11a, 13C (101 MHz, acetone-d6), δC 194.2 (CO), 170.2 (C(2, 9) L2),
19a or 11b, 19b)), 4.76 (d, J = 14.0 Hz, 2H, CH2(11a, 19a or 11b, 152.8 (C(2, 6) Py), 146.6 (C(4b, 6b) L2), 141.9 (C(8, 3) L2), 141.1
19b)), 3.30–2.92 (m, 4H, CH2(14, 16)), 2.59–2.38 (m, 2H, (C(4) Py), 130.5 (C(4a, 6a) L2), 128.6 (C(4, 7) L2), 127.9 (C(5,6)
CH2(13a, 17a or 13b, 17b)), 2.38–2.16 (m, 2H, CH2(13a, 17a or L2), 127.2 (C(3, 5) Py), 71.3 (C(14, 16) L2), 45.0 (C(11, 19) L2),
13b, 17b)). 31P (162 MHz, acetone-d6): δP 31.7; 13C NMR 33.2 (C(13, 17) L2). MS (MALDI+), m/z 863.4 ([M − OCF3 + H],
(101 MHz acetone-d6), δC 197.4 (CO), 196.1 (CO), 169.2 (C(2, 9) 8.80%) calculated 863.4, 692.2, ([M − AgCF3SO3]+, 4.27%) cal-
L2), 148.1 (C(4b, 6b) L2), 146.3 (C(2), Im), 141.9 (C(8, 3) L2), culated 692.07, 613.2 ([M − Py − AgCF3SO3]+, 96.5%) calculated
135.0 (d, J = 13.6 Hz, ortho-Ph), 133.3 (d, J = 2.6 Hz, para-Ph), 613.03; IR (solid, cm−1, (CO)): 2034, 1937, 1923.
130.5 (d, J = 11.9 Hz, meta-Ph), 129.3 (C(4a, 6a) L2), 128.9 (d,
J = 63.5 Hz, ipso-Ph), 127.9 (C(5), Im), 127.51 (C(5, 6) L2),
127.52 (C(4, 7) L2), 127.2 (C(4), Im), 72.7 (C(14, 16) L2), 45.1
Acknowledgements
(C(1, 19) L2), 33.3 (C(13, 17) L2). MS (MALDI+): m/z 985.1 ([M −
2Ph]+ 94.4%) calculated: 985.04, m/z 909.0 ([M − 3Ph]+ 4.8%) Authors thank the Ministerio de Economía y Competitividad-
calculated: 908.0, m/z 612.8 ([M − Im − Au(PPh)3]+, 51.2%) cal- FEDER (CTQ2013-48635-C2-1-P) and DGA-FSE (E77) and
culated 613.03; IR (solid, cm−1, (CO)): 2024, 1931, 1895; Anal. Fondazione banco di Sardegna for financial support.
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