Oxidorhenium(V) complexes with tridentate and tetradentate phenol-based ligands

Article abstract of DOI:10.1002/ejic.201000771

The synthesis of oxidorhenium(V) complexes with tridentate and potentially tetradentate ligands of the type [ReOX₂(L)] {X = Cl or Br; L = 2-[CH₂N(Me)CH₂CH₂OCH₃]-4,6-di-tBu- phenolate, 2-[CH₂N(Me)CH₂CH₂SCH ₂CH₃]-4,6-di-tBu-phenolate, 2-[CH₂N(Me)CH ₂CH₂N(CH₃)₂]-4,6-di-tBu-phenolate, 2-[CH₂N(Me)CH₂CH₂N(CH₂CH ₃)₂]-4,6-di-tBu-phenolate, 2-[CH₂N(CH ₂CH₂OCH₃)₂]-4,6-di-tBu-phenolate,2- [CH₂N(CH₂CH₂SCH₂CH₃) ₂]-4,6-di-tBu-phenolate, 2-[CH₂N{CH₂CH ₂N(CH₂CH₃)₂}₂]-4,6-di- tBu-phenolate} 1-14 is reported. All complexes were spectroscopically characterized and shown to be isomerically pure. Compounds 1, 2, 9, and 11 were crystallographically characterized and show similar octahedral geometries with trans O=Re-O and cis O=Re-Cl bonds. All synthesized complexes 1-14 are catalyst precursors for the epoxidation of cyclooctene with tert-butyl hydrogenperoxide (TBHP). Yields of the formed epoxide were up to 55a% with all precursors. Oxidorhenium(V) complexes of the type [ReOX₂L] (X = Cl, Br) that contain tridentate and tetradentate phenolate-based ligands were prepared and tested for their catalytic activity in epoxidation reactions.

Full text of DOI:10.1002/ejic.201000771

FULL PAPER
DOI: 10.1002/ejic.201000771
Oxidorhenium(V) Complexes with Tridentate and Tetradentate Phenol-Based
Ligands
Pedro Traar,[a] Albert Schröckeneder,[a] Martina E. Judmaier,[a] Ferdinand Belaj,[a]
Judith Baumgartner,[b] Anna Sachse,[a][‡] and Nadia C. Mösch-Zanetti*[a]
Keywords: Rhenium / Polydentate ligands / Epoxidation / Phenols
The synthesis of oxidorhenium(V) complexes with tridentate
and potentially tetradentate ligands of the type [ReOX2(L)]
{X = Cl or Br; L = 2-[CH2N(Me)CH2CH2OCH3]-4,6-di-
tBu-phenolate, 2-[CH2N(Me)CH2CH2SCH2CH3]-4,6-di-tBu-
phenolate, 2-[CH2N(Me)CH2CH2N(CH3)2]-4,6-di-tBu-phen-
olate, 2-[CH2N(Me)CH2CH2N(CH2CH3)2]-4,6-di-tBu-phen-
reported. All complexes were spectroscopically characterized
and shown to be isomerically pure. Compounds 1, 2, 9, and
11 were crystallographically characterized and show similar
octahedral geometries with trans O=Re–O and cis O=Re–Cl
bonds. All synthesized complexes 1–14 are catalyst precur-
sors for the epoxidation of cyclooctene with tert-butyl hydro-
genperoxide (TBHP). Yields of the formed epoxide were up
to 55% with all precursors.
olate,
2-[CH2N(CH2CH2OCH3)2]-4,6-di-tBu-phenolate,
2-
2-[CH2N(CH2CH2SCH2CH3)2]-4,6-di-tBu-phenolate,
[CH2N{CH2CH2N(CH2CH3)2}2]-4,6-di-tBu-phenolate} 1–14 is
in oxidation reactions, oxidorhenium(V) compounds were
recently found to be catalysts in several other reactions. To-
ste and co-workers discovered the rhenium(V)-catalyzed
transformation of unsaturated organic substrates by hydro-
silylation reactions.[21,22] Subsequently, several rhenium(V)
catalysts for the reduction of various substrates were devel-
oped.[23] The scope of these transformations has only begun
to be explored. Last but not least, due to the water stability
and the occurrence of the radioactive isotopes 186/188Re, ox-
idorhenium(V) compounds have been applied in therapeutic
nuclear medicine.[24]
Phenolate-based ligands have enjoyed much success in
the stabilization of metal compounds, which are used in
various chemical transformations.[25–28] These ligand types
range from simple mono-phenoxide systems to bis-phenox-
ide systems, many of which are easily obtained by means of
Schiff base or Mannich condensation reactions. The mono-
phenoxide systems are found as tri- or tetradentate ligands
depending on the substituents at the nitrogen atom of the
methyleneamine close to the aromatic system (Scheme 1).
In 2003, Tolman and co-workers used the chelating triden-
tate ligand ONNMe for the preparation of highly active
zinc catalysts in the polymerization of lactide with good
control and high rate.[29] Tetradentate mono-phenoxido li-
gands remained largely unexplored until Kol and co-
workers used the chelating tetradentate ligand ONOO for
the preparation of zirconium and titanium alkoxide com-
pounds [M(κ3-ONNOO)(OtBu)3].[30] Both complexes reveal
octahedral geometries with a facial coordination of the li-
gand in a tridentate fashion and a dangling donor arm that
coordinates upon formation of cationic compounds [M(κ4-
ONOO)(OtBu)2]+. In 2006, Gibson and co-workers pre-
Introduction
Oxidorhenium(V) complexes that contain polydentate li-
gands have attracted considerable interest in recent years
due to their application as catalysts in oxygen atom-transfer
reactions (OAT).[1–9] Mechanistic aspects were thoroughly
investigated by Espenson and co-workers to reveal the two
most prominent requirements for a given rhenium(V) com-
pound to be an active catalyst: the active site must allow
coordination of the oxygen atom donor such as pyridine N-
oxide, dimethyl sulfoxide, or tert-butyl hydroperoxide
(TBHP),[10] and the breaking of the O–X bond within the
oxygen donor (e.g., in Py–O) is facilitated by nucleophiles.[3]
Rhenium(V) compounds were particularly well studied, be-
cause they are easily prepared and are usually moisture-
and air-stable. Also, high-oxidation-state rhenium(VII)
compounds were investigated and, for example, methyl-
trioxidorhenium(VII) (MTO) and derivatives thereof
proved to be successful catalysts for various oxidations in-
cluding epoxidation reactions.[11–15] However, the sensitivity
of MTO towards water sometimes hampers high yields. For
this reason, more stable oxidorhenium(V) complexes were
also investigated as catalysts in epoxidations albeit as yet
with limited success.[16–20] The rhenium(V) systems investi-
gated so far show significantly lower activity or productiv-
ity than rhenium(VII) systems. In contrast to applications
[a] Institute of Chemistry, Karl Franzens University Graz,
Schubertstrasse 1, 8010 Graz, Austria
[b] Institute for Inorganic Chemistry, Graz University of
Technology,
Stremayrgasse 9, 8010 Graz, Austria
[‡] Current address: GXC Coatings GmbH, 38642 Goslar
5718
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2010, 5718–5727

Oxidorhenium(V) Complexes with Phenol-Based Ligands
Scheme 1. (a) According to known procedures:[33] amine [(2-methoxyethyl)(methyl)amine for ONO; (2-ethylthioethyl)(methyl)amine for
ONS; N,N,NЈ-trimethylethylenediamine for ONNMe; N,N-diethyl-NЈ-methylethylenediamine for ONNEt], Et3N, dioxane, overnight. (b)
amine [bis(2-methoxyethyl)amine for ONOO; bis(2-ethylthioethyl)amine for ONSS; N,N,NЈ,NЈ-tetraethyldiethylenetriamine for
ONNNEt], Et3N, dioxane, overnight.
pared a series of metal complexes with potentially tetraden- the literature.[29–33] The synthetic strategy reported by Jud-
tate phenolate ligands (ONNNEt, ONOO; Scheme 1) and maier et al.[33] for the synthesis of tridentate ligands was
found the denticity of the ligands to depend on the coordi- adopted for the already known tetradentate ligands ONOO
nation requirement of the metal center.[31] Bidentate (Al), and ONNNEt to give more consistent and higher yields.
tridentate (Mg, Ca, Zn), and tetradentate (K, Cr, Fe, Co) Thus, the ligand syntheses followed a three-step procedure
binding modes have been established by X-ray diffraction that started from 2,4-di-tert-butylphenol, which was con-
analysis. Furthermore, NMR spectroscopic studies in solu- verted into 2-hydroxy-3,5-di-tert-butylbenzyl chloride.[34]
tion of the zinc compounds with the ligands ONNNEt and Subsequent treatment of the obtained chloride with the cor-
ONOO indicate a dynamic exchange of both donor arms. responding secondary amines gave the desired ligands in
The remarkable diversity of the binding capability found excellent yields and were used without further purification.
with this type of ligands as well as the potential to obtain In the same way, the new ligand ONSS was obtained in a
potentially cationic rhenium(V) complexes led us to explore 90% yield (Scheme 1). All ligands were characterized by
the coordination chemistry of rhenium(V) complexes. We NMR spectroscopy and elemental analyses. Prior to coordi-
were interested as to whether such a change of denticity on nation to the metal atom, all ligands were converted into
demand can be applied in epoxidation reactions to obtain their potassium salt by the use of potassium hydride in
more active catalytic systems. Here we report the prepara- THF.
tion of a series of oxidorhenium(V) complexes with triden-
tate (ONO, ONS, ONNMe, ONNEt) and tetradentate
(ONOO, ONSS, ONNNEt) phenol-based ligands and
tested their catalytic properties in the epoxidation of cyclo-
octene.
The desired complexes 1–8 were obtained by the use of
the rhenium precursors [ReOX3(OPPh3)(SMe2)] (X = Cl or
Br) (for 1–4, 7, 8) or [ReOBr3(PPh3)2] (for 5 and 6) in the
presence of the corresponding potassium salt of the ligands
ONO, ONS, ONNMe, and ONNEt in toluene heated at
reflux (Scheme 2).[20] The metal precursors [ReOX3-
(OPPh3)(SMe2)][35,36] (X = Cl or Br) and [ReOBr3-
(PPh3)2][37] were prepared essentially according to known
procedures.
Results and Discussion
Synthesis of Compounds with Tri- and Tetradentate
Ligands
Analogously, complexes 9–14 were obtained on treat-
Two procedures for the formation of the tridentate li- ment of the potassium salts of ONOO, ONSS, ONNNME,
gands ONO, ONS, ONNMe, and ONNEt and the tetraden- and ONNNEt with [ReOX3(OPPh3)(SMe2)] (X = Cl or Br)
tate ligands ONOO and ONNEt are readily available from in toluene heated at reflux (Scheme 3).
Scheme 2. (a) KH, THF, crude. (b) [ReOX3(OPPh3)(SMe2)] or [ReOX3(PPh3)2] (X = Cl or Br), toluene, reflux, 2 h.
Eur. J. Inorg. Chem. 2010, 5718–5727
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5719

N. C. Mösch-Zanetti et al.
FULL PAPER
Scheme 3. (a) KH, THF, crude. (b) [ReOX3(OPPh3)(SMe2)] (X = Cl or Br), toluene, reflux, 2 h.
Removal of the solvent and recrystallization of the ob- δ = 3.42, 4.47 ppm (9) and 3.43, 4.54 ppm (12), respectively,
tained residue from a mixture of chloroform/heptane gave in which the downfield resonance can be assigned to the
the desired complexes 1–14 in 43–69% yields. All complexes protons of coordinated OMe groups as also found in com-
show high air and moisture stability.
plexes 1 and 5 (δ = 4.45 and 4.53 ppm for OMe). The up-
Complexes 1–14 were characterized by NMR and IR field-shifted singlet points to a noncoordinated OMe group
spectroscopy and elemental analyses. For compounds 1, 2, whose signal is in the same range as that found for the free
9, and 11 single-crystal X-ray diffraction analyses were per- ligand. For complexes 10, 11, 13, and 14, 1H NMR spectro-
formed. The IR spectra of the complexes gave a characteris- scopic analyses also indicated that the additional side arm
tic stretching frequency for the Re=O moiety, and elemental was not coordinated, which was confirmed by single-crystal
analyses confirmed the basic formula of [ReOX2L] (X = Cl structure analyses of 9 and 11 (vide infra).
or Br; L = ligand) for all compounds.
Formation of compounds 1–8 with tridentate ligands can
in principle form isomers with the ligand to be coordinated
in a meridional or facial fashion with the oxygen atom of
Molecular Structures of [ReOCl2(ONO)] (1),
[ReOCl2(ONS)] (2), [ReOCl2(ONOO)] (9), and
[ReOCl2(ONNNEt)] (11)
the phenol moiety in a trans position towards the oxygen
or chlorine atom of the rhenium moiety. NMR spectra of
all compounds confirmed the occurrence of only one iso-
mer in solution, which was shown to contain a facially co-
ordinated ligand towards the rhenium atom and a trans co-
Structures of compounds 1, 2, 9, and 11 were determined
ordination of the phenol oxygen atom towards the oxido by X-ray diffraction analyses after crystallization from a
group at the rhenium atom as confirmed by X-ray diffrac- chloroform/heptane mixture. Molecular views are shown in
tion analysis (vide infra). In 1H NMR spectroscopy, the Figure 1, crystallographic data are presented in Table 2, and
methylene groups present in the ligand gave a characteristic selected bond lengths and angles are given in Table 1. All
splitting for the diastereotopic protons. The protons of the complexes show a six-coordinate rhenium atom with dis-
methylene fragment attached to the aromatic ring gave two torted octahedral geometries and trans O–Re=O and cis
doublets at δ ≈ 3.5 and 5.5 ppm, which is indicative of com- Cl–Re=O bonds. The Re–N bond [Re(1)–N(2) 2.209(4) Å
plex formation. The formation of only one isomer of com- for 1; 2.235(3) Å for 2; Re(1)–N(1) 2.230(8) Å for 9; and
plexes 1–8 by using ONO, ONS, ONNMe, and ONNEt is Re(2)–N(1) 2.195(5) Å, Re(2)–N(2) 2.228 Å for 11] is signif-
in contrast to reported oxidomolybdenum compounds icantly longer than the Re–O bond [Re(1)–O(1) 1.904(3) Å
[MoO2Cl(L)] in which two isomers were found in solution for 1; Re(1)–O(2) 1.913(2) Å for 2; Re(1)–O(2) 1.907(6) Å
for complexes that contained ONNMe and ONNEt li- for 9; and Re(1)–O(1) 1.916(5) Å for 11]. The trans coordi-
gands.[33]
nation of the ligand oxygen atom towards the oxygen atom
Compared to the tridentate ligands, the tetradentate de- attached to the rhenium atom is well documented in the
rivatives consist of an additional donor atom. This type of literature.[7,18,40–42] For distorted octahedral ReVO com-
ligands was previously shown to coordinate in a tetraden- plexes with oxygen-containing bidentate ligands, it is sug-
tate fashion and form a cationic complex with a chloride gested that O–Re=O corresponds to a minimum of trans
counterion.[30] This encouraged us to investigate tetraden- weakening caused by the Re=O multiple bond. In addition,
tate ligands and their coordination mode towards the rhe- the repulsion exerted by the Re=O atom causes a compres-
nium moiety. A possible formation of a rhenium complex sion field that tends to increase the mean O=Re–Lcis angle
of the type [ReOCl(L)]+Cl– may form a reactive species use- beyond 90°.[43] All complexes show a facial coordination of
ful in catalytic applications.[2,38,39] Analogously to com- the ligand towards the rhenium moiety. The equatorial
plexes 1–8, NMR spectroscopic analyses of complexes 9– plane of the complexes consists of the two halide atoms, the
14 indicated the formation of only one isomer of the type nitrogen atom, and the chalcogen atom (compounds 1, 2,
[ReOCl2L] with a dangling donor arm. The 1H NMR spec- 9) or an additional nitrogen atom (compound 11) from the
tra of complexes 9 and 12 gave chemical shifts for OCH3 of ligand. All complexes gave bond lengths for Re=O
5720
www.eurjic.org
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2010, 5718–5727

Oxidorhenium(V) Complexes with Phenol-Based Ligands
Figure 1. Molecular views of compounds 1, 2, 9, and 11 with selected atom numbering. Hydrogen atoms are omitted for clarity. Ellipsoids
for compound 11 are given at the 30% probability level.
Table 1. Selected bond lengths [Å] and angles [°] for [Re-
OCl2(ONO)] (1), [ReOCl2(ONS)] (2), [ReOCl2(ONOO)] (9), and
(11)] and Re–Cl [2.3807(13) and 2.3765(12) Å (1),
[ReOCl2(ONNNEt)] (11).
[1.696(3) Å (1), 1.692(2) Å (2), 1.682(7) Å (9), 1.676(5) Å
2.4100(10) and 2.3704(10) Å (2), 2.365(3) and 2.357(3) Å
Compound 1
Compound 2
(9), 2.4090(18) and 2.3770(17) Å (11)] within the expected
range for other [ReOCl2L] structures.[18,20,44]
Re(1)–O(3)
Re(1)–O(1)
Re(1)–Cl(1)
Re(1)–Cl(2)
Re(1)–O(2)
Re(1)–N(2)
O(3)–Re(1)O(1)
Cl(2)–Re(1)–N(2) 169.6(1)
Cl(1)–Re(1)–O(2) 174.36(9)
O(2)–Re(1)–N(2) 79.8(1)
O(3)–Re(1)–Cl(1) 95.9(1)
O(3)–Re(1)–Cl(2) 99.90(1)
Cl(1)–Re(1)–Cl(2) 89.56(5)
O(1)–Re(1)–N(2) 80.6(1)
1.696(3)
1.904(3)
2.381(1)
2.377(1)
2.144(3)
2.209(4)
167.4(2)
Re(1)–O(1)
Re(1)–O(2)
Re(1)–Cl(1)
Re(1)–Cl(2)
Re(1)–S(1)
Re(1)–N(1)
O(1)–Re(1)–O(2) 168.8(1)
Cl(2)–Re(1)–N(1) 169.63(8)
Cl(1)–Re(1)–S(1) 173.39(3)
1.692(2)
1.913(2)
2.410(1)
2.370(1)
2.421(1)
2.235(3)
In complex 1, the chlorine atoms Cl(1) and Cl(2) are co-
ordinated in cis position to each other with comparable
bond lengths of Re(1)–Cl(1) [2.3807(13) Å] and Re(1)–Cl(2)
[2.3765(12) Å] including an angle Cl(1)–Re(1)–Cl(2) of
89.56(5)°. The nitrogen atom N(2) is in trans position to
the chlorine atom Cl(2) with an angle of N(2)–Re(1)–Cl(2)
169.56(10)°, and the oxygen atom O(2) is in trans position
to the chlorine atom Cl(1) with an angle of Cl(1)–Re(1)–
O(2) 174.36(9)°. The facially coordinated ligand shows a
trans coordination of the phenol oxygen atom towards the
Re=O unit with an angle O(1)–Re(1)–O(3) of 167.35(16),
whereas donor atoms of the ligand coordinate in cis posi-
tion to each other including angles O(1)–Re(1)–N(2) of
80.60(14)°, N(2)–Re(1)-(O2) of 79.84(14)°, and O(1)–Re(1)–
O(2) of 84.43(13)°. The coordinated atoms N(2) and O(2)
of the side arm in the phenolate ring form a five-membered
ring that includes C(23), C(24), and the rhenium atom
Re(1), in which C(24) is 0.665 Å out of the plane and ori-
ented in the same direction as O(3).
S(1)–Re(1)–N(1)
83.26(8)
O(1)–Re(1)–Cl(1) 94.22(9)
O(1)–Re(1)–Cl(2) 101.00(9)
Cl(1)–Re(1)–Cl(2) 88.21(4)
O(2)–Re(1)–N(1) 80.35(10)
Compound 9
Compound 11
Re(1)–O(1)
Re(1)–O(2)
Re(1)–Cl(2)
Re(1)–Cl(1)
Re(1)–N(1)
Re(1)–O(3)
O(1)–Re(1)–O(2) 166.6(3)
N(1)–Re(1)–Cl(2) 171.1(2)
O(3)–Re(1)–Cl(1) 172.8(2)
O(3)–Re(1)–N(1) 79.8(3)
O(1)–Re(1)–Cl(1) 97.9(2)
O(1)–Re(1)–Cl(2) 99.6(3)
Cl(1)–Re(1)–Cl(2) 88.2(1)
O(2)–Re(1)–N(1) 81.3(3)
1.682(7)
1.907(6)
2.365(3)
2.357(3)
2.230(8)
2.136(7)
Re(2)–O(2)
Re(2)–O(1)
Re(2)–Cl(1)
Re(2)–Cl(2)
Re(2)–N(2)
Re(2)–N(1)
O(2)–Re(2)–O(1) 169.9(2)
Cl(2)–Re(2)–N(1) 167.2(2)
Cl(1)–Re(2)–N(2) 176.8(2)
N(1)–Re(2)–N(2) 82.3(2)
O(2)–Re(2)–Cl(1) 91.7(2)
O(2)–Re(2)–Cl(2) 102.8(2)
Cl(1)–Re(2)–Cl(2) 88.52(6)
O(1)–Re(2)–N(1) 80.5(2)
1.676(5)
1.916(5)
2.409(1)
2.377(2)
2.228(6)
2.195(5)
In complex 2, the distance Re(1)–S(1) of 2.4215(10) Å is
longer than that in complex 1, in which an oxygen atom
[OMe, O(2)] coordinates with an Re(1)–O(2) bond length
of 2.144(3) Å. This indicates that an oxygen atom is a better
ligand than a sulfur atom. The chlorine atoms Cl(1) and
Eur. J. Inorg. Chem. 2010, 5718–5727
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5721

N. C. Mösch-Zanetti et al.
FULL PAPER
Cl(2) are coordinated in a cis position to each other with Catalytic Epoxidations
comparable bond lengths of Re(1)–Cl(1) [2.4100(10) Å] and
Few oxidorhenium(V) complexes are known to show
catalytic activity in epoxidation reactions.[16,17,19,41,45] Re-
cently, we investigated complexes of the type [Re-
OCl2(L)(PPh3)] and [ReOCl(L)2] (L = oxo iminato ligands)
in the reaction of cyclooctene with TBHP in which a con-
version to the epoxide of 55% was observed.[18,20] To ex-
plore the influence of additional donors in the catalyst on
the catalytic activity, we tested rhenium complexes 1 to 14
in the model reaction shown in Scheme 4.
Re(1)–Cl(2) [2.3704(12) Å] including an angle Cl(1)–Re(1)–
Cl(2) of 88.21(4)°. The nitrogen atom N(1) is in trans posi-
tion to the chlorine atom Cl(2) with an angle N(1)–Re(1)–
Cl(2) of 169.63(8)°, and the sulfur atom S(1) is in trans posi-
tion to the chlorine atom Cl(1) with an angle Cl(1)–Re(1)–
S(2) of 173.39(3)°. The facially coordinated ligand shows a
trans coordination of the phenol oxygen atom towards the
Re=O unit with an angle O(1)–Re(1)–O(2) of 168.81(10),
whereas donor atoms of the ligand coordinate in cis posi-
tion to each other including angles N(1)–Re(1)–S(1) of
83.26(8)°, O(2)–Re(1)–N(1) of 80.35(10)°, and O(2)–Re(1)–
S(1) of 89.13(9)°. The coordinated atoms N(1) and S(1) of
the side arm in the phenolate ring form a five-membered
ring that includes C(17), C(18), and the rhenium atom
Re(1), in which C(18) is 0.734 Å out of the plane and ori-
ented in the same directions as O(1).
Scheme 4. (a) TBHP, ReV (2 mol-%), CHCl3, 50 °C.
In complex 9, the chlorine atoms Cl(1) and Cl(2) are co-
ordinated in cis position to each other with comparable
bond lengths Re(1)–Cl(1) of 2.357(3) Å and Re(1)–Cl(2) of
2.365(3) Å including an angle Cl(1)–Re(1)–Cl(2) of
88.24(10)°. The nitrogen atom N(1) is in trans position to
the chlorine atom Cl(2) with an angle N(1)–Re(1)–Cl(2) of
171.1(2)°, and the oxygen atom O(3) is in trans position to
the chlorine atom Cl(1) with an angle Cl(1)–Re(1)–O(3) of
172.8(2)°. The facially coordinated ligand shows a trans co-
ordination of the phenol oxygen atom towards the Re=O
unit with an angle O(1)–Re(1)–O(2) of 166.6(3), whereas
donor atoms of the ligand coordinate in cis position to each
other and include angles N(1)–Re(1)–O(3) of 79.8(3)°,
O(2)–Re(1)–N(1) of 81.3(3)°, and O(2)–Re(1)–O(3) of
83.3(3)°. The coordinated atoms N(1) and O(3) of the side
arm in the phenolate ring form a five-membered ring that
includes C(16), C(17), and the rhenium atom Re(1), in
which C(17) is 0.643 Å out of the plane and oriented in the
same direction as O(1). The additional side arm is oriented
in the same direction as O(1).
The catalytic reactions were performed in chloroform at
50 °C by the use of 2 mol-% of the corresponding catalyst
and a threefold excess amount of the peroxide (Scheme 4).
The conversion to the epoxide was monitored by GC–MS
analyses, and complexes 1–14 were tested for their catalytic
activity by using tert-butyl hydrogenperoxide (TBHP) as the
oxidant. However, all complexes gave comparable conver-
sion of the alkene into the epoxide with a yield in the range
of 50–55%. A representative epoxidation reaction moni-
tored by GC–MS when using compound 2 as the catalyst
is shown in Figure 2.
In complex 11, the chlorine atoms Cl(1) and Cl(2) are
coordinated in cis position to each other with comparable
bond lengths Re(2)–Cl(1) of 2.4090(18) Å and Re(2)–Cl(2)
of 2.3770(17) Å, including an angle Cl(1)–Re(2)–Cl(2) of
88.52(6)°. The nitrogen atom N(1) is in trans position to
the chlorine atom Cl(2) with an angle N(1)–Re(2)–Cl(2) of
167.2(2)°, and the nitrogen atom N(2) is in trans position
to the chlorine atom Cl(1) with an angle Cl(1)–Re(2)–N(2)
of 176.75(15)°. The facially coordinated ligand shows a
trans coordination of the phenol oxygen atom towards the
Figure 2. Epoxidation of cyclooctene by using catalyst [Re-
OCl2(ONS)] (2).
The catalytic activity is fast within the first 60 min with-
Re=O unit with an angle O(1)–Re(2)–O(2) of 169.9(2), out the occurrence of an induction period. No significant
whereas donor atoms of the ligand coordinate in cis posi- increase in yield was obtained beyond 60 min. Apparently,
tion to each other and include angles N(1)–Re(2)–N(2) of the catalytically active species is quickly formed but is only
82.3(2)°, O(1)–Re(1)–N(1) of 80.5(2)°, and O(1)–Re(1)– stable for approximately 1 h. Furthermore, is seems to be
N(2) of 91.2(2)°. The coordinated atoms N(1) and N(2) of independent of the ligand at the rhenium atom, because
the side arm in the phenolate ring form a five-membered identical yields were obtained. Relative to our previous re-
ring that includes C(16), C(17), and the rhenium atom sults with bidentate ligands,[20] additional donors in the li-
Re(1), in which C(17) is 0.645 Å out of the plane and ori- gand system did not improve the stability of the complexes
ented in the opposite direction as O(2). The additional side in the catalytic reaction. We ruled out perrhenate to be the
arm is oriented in the same direction as O(2).
active species, because we tested sodium perrhenate as a
5722
www.eurjic.org
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2010, 5718–5727

Oxidorhenium(V) Complexes with Phenol-Based Ligands
X-ray Structural Determination: For X-ray structural analyses, the
crystals were mounted onto the tip of glass fibers, and data collec-
tion was performed at low temperature by using graphite-mono-
chromated Mo-Kα radiation (λ = 0.71073 Å) with a Bruker-AXS
catalyst in the epoxidation reaction under analogous condi-
tions and found a 27 mol-% yield of the corresponding ep-
oxide. As the active species, an oxidized form of our com-
pounds with a dioxidorhenium(VII) core is conceivable
since the ReVII complex of the type [ReO2(hoz)2]+ with the
(hydroxyphenyl)oxazoline ligand (hoz) has been crystallo-
graphically characterized.[46] However, the identification of
the active catalyst has so far remained elusive. Attempts to
use H2O2 instead of TBHB as the oxidant gave no conver-
2
SMART APEX CCD diffractometer. The data were reduced to Fo
and corrected for absorption effects with SAINT[47] and SAD-
ABS,[48] or an empirical absorption correction[49] was applied. The
structures were solved by direct methods or by Patterson superposi-
tion procedures when direct methods failed, and refined by full-
matrix least-squares method (SHELXL97).[50] For structures 9 and
sion to the epoxide. Other olefins proved to be unreactive 11, restraints were applied to model the disordered ethyl and/or
tert-butyl groups. All non-hydrogen atoms were refined with aniso-
tropic displacement parameters without any constraints. All hydro-
gen atoms were located in calculated positions to correspond to
standard bond lengths and angles. Common isotropic displacement
parameters were refined for the hydrogen atoms bonded to the
same C atom or to the same phenyl ring. All diagrams were drawn
with 50% probability thermal ellipsoids and all hydrogen atoms
were omitted for clarity. A summary of the crystallographic data is
listed in Table 2. CCDC-783689 (1), -784006 (2), -783932 (9), and
-783931 (11) contain the supplementary crystallographic data for
this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
towards epoxidation when complexes 1–14 were used as cat-
alysts.
Conclusion
Oxidorhenium(V) complexes of the type [ReOX2L] (X =
Cl or Br) 1–14 that contain tridentate and potentially tetra-
dentate ligands {L = 2-[CH2N(Me)CH2CH2OCH3]-4,6-di-
tBu-phenolate,
2-[CH2N(Me)CH2CH2SCH2CH3]-4,6-di-
tBu-phenolate, 2-[CH2N(Me)CH2CH2N(CH3)2]-4,6-di-tBu-
phenolate, 2-[CH2N(Me)CH2CH2N(CH2CH3)2]-4,6-di-tBu-
phenolate, 2-[CH2N(CH2CH2OCH3)2]-4,6-di-tBu-phenol-
ate, 2-[CH2N(CH2CH2SCH2CH3)2]-4,6-di-tBu-phenolate,
2-[CH2N{CH2CH2N(CH2CH3)2}2]-4,6-di-tBu-phenolate}
were prepared and characterized. Despite the fact that sev-
eral isomers can be formed on reaction of the ligands with
rhenium precursors, all complexes were obtained in isomer-
ically pure form. The prepared ligands formed complexes
with facial coordination around the metal center. The tetra-
dentate ligands coordinate in a tridentate fashion with a
dangling arm. Compounds 1–14 proved to be catalytic pre-
cursors for the epoxidation of cyclooctene with TBHP to
give yields of the formed epoxide up to 55%.
General Procedure for the Preparation of the Ligands: Triethylamine
(Et3N) was added to a solution of 3,5-di-tert-butyl-2-hydroxybenzyl
chloride[34] and the respective amine in dioxane. The reaction mix-
ture was stirred overnight and filtered through a plug of Celite. The
filtrate was concentrated in vacuo to give the corresponding ligand
as an oil, which was used without further purification.
Synthesis of ONOO: The ligand was prepared by the reaction of
3,5-di-tert-butyl-2-hydroxybenzyl chloride (3.40 g, 13.4 mmol),
bis(2-methoxyethyl)amine (1.78 g, 13.4 mmol), and Et3N (2.7 g,
27 mmol) in dioxane (70 mL) to give ONOO (3.97 g, 84%) as a
yellow viscous oil. The data for NMR spectroscopy and elemental
analysis are consistent with those reported in the literature.[30,31]
Synthesis of ONNNEt: The ligand was prepared by the reaction
of 3,5-di-tert-butyl-2-hydroxybenzyl chloride (3.25 g, 12.7 mmol),
N,N,NЈ,NЈ-tetraethyldiethylenetriamine (2.75 g, 12.7 mmol), and
Et3N (2.6 g, 26 mmol) in dioxane (70 mL) to give ONNNEt
(4.98 g, 90%) as a light brown oil. The data for NMR spectroscopy
and elemental analysis are in good agreement with those reported
in the literature.[31]
Experimental Section
General: Syntheses were performed under argon by using common
Schlenk techniques with subsequent workup under ambient condi-
tions. The metal precursors[35–37] [ReOCl3(OPPh3)(SMe2)],
[ReOBr3(OPPh3)(SMe2)], and [ReOBr3(PPh3)2], as well as the li-
gands ONO, ONS, ONNMe, and ONNEt[29,32,33] were prepared
according to known procedures. Chemicals were purchased from
commercial sources and were used without further purification.
Solvents were purified with a Pure Solv Solvent Purification Sys-
tem. NMR spectra were recorded with a Bruker (300 MHz) instru-
ment. Chemical shifts (δ) are given in ppm and are referenced to
partially protonated solvent or internal standard. Signals are de-
scribed as s (singlet), d (doublet), dd (double doublet), t (triplet),
dt (double triplet), or m (multiplet), and coupling constants (J) are
given in Hertz (Hz). Elemental analyses were carried out with a
Heraeus Vario Elementar automatic analyzer. Mass spectra were
recorded with an Agilent 5973 MSD Direct Probe by using the EI
ionization technique. Samples for IR spectroscopy were prepared
as KBr pellets and measured with a Perkin–Elmer FTIR 1725X
spectrometer. GC–MS measurements were performed with an Ag-
ilent 7890A with an Agilent 19091J-433 column coupled to an Ag-
ilent 5975C mass spectrometer.
Synthesis of ONSS: The ligand was prepared by the reaction of
3,5-di-tert-butyl-2-hydroxybenzyl chloride (4.39 g, 17.2 mmol),
bis(2-ethylthioethyl)amine[51] (3.33 g, 17.2 mmol), and Et3N (3.5 g,
35 mmol) in dioxane (100 mL) to give ONSS (6.30 g, 90%) as a
brown oil. 1H NMR (C6D6): δ = 0.97 (t, J = 7.4 Hz, 6 H, CH3),
1.35 (s, 9 H, CH3), 1.69 (s, 9 H, CH3), 2.14 (q, J = 7.4 Hz, 4 H,
CH2), 2.38 (t, J = 7.8 Hz, 4 H, CH2), 2.49 (t, J = 7.7 Hz, 4 H,
CH2), 3.38 (s, 2 H, CH2), 6.88 (d, J = 2.31 Hz, 1 H, Ar), 7.48 (d,
J = 2.4 Hz, 1 H, Ar), 10.54 (br. s, 1 H, OH) ppm. C23H41NOS2
(411.70): calcd. C 67.10, H 10.04, N 3.40; found C 66.59, H 9.83,
N 3.93. IR (KBr): ν = 2958, 2868, 1482, 1458, 1390, 1362, 1300,
˜
1236, 1202, 1164, 1100, 876 cm–1. EI-MS: m/z (%) = 411 (13) [M+].
General Procedure for the Preparation of Rhenium Complexes 1–
14: The respective potassium salt of the ligand (KONO, KONS,
KONNMe, KONNEt) in toluene was added to a suspension of the
precursor [ReOX3(OPPh3)(SMe2)] or [ReOX3(PPh3)2] (X = Cl or
Br) in toluene. A color change from brown to green indicated the
start of the reaction after 5 min of stirring at room temperature.
Heating to reflux for 2 h gave a dark green solution with a dark
Eur. J. Inorg. Chem. 2010, 5718–5727
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5723

N. C. Mösch-Zanetti et al.
Table 2. Crystallographic data for [ReOCl2(ONO)] (1), [ReOCl2(ONS)] (2), [ReOCl2(ONOO)] (9), and [ReOCl2(ONNNEt)] (11).
FULL PAPER
Compound 1
Compound 2
Compound 9
Compound 11
Empirical formula
Mr [gmol]
Color, habit
Crystal size [mm]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
C20H33Cl5NO3Re
698.92
green, block
0.20ϫ0.20ϫ0.16
monoclinic
P21/n
7.933(1)
28.874(3)
11.844(2)
90
C28H50Cl2NO4ReS
753.85
green, needle
0.20ϫ0.10ϫ0.10
monoclinic
P21/n
10.226(2)
11.167(2)
28.792(6)
90
C42H72Cl4N2O8Re2
1247.22
green, needle
0.38ϫ0.22ϫ0.20
monoclinic
Pc
7.7956(16)
31.144(6)
12.319(4)
90
C27H50Cl2N3O2Re
705.8
green, block
0.36ϫ0.24ϫ0.14
monoclinic
P21/c
7.768(2)
25.606(5)
17.686(5)
90
β [°]
100.01(1)
90
2671.8(7)
4
98.61(3)
90
3250.8(1)
4
124.19(2)
90
2474.0(1)
2
115.60(3)
90
3172.7(1)
4
γ [°]
V [Å3]
Z
T [K]
95
1.738
5.069
1376
100(2)
1.540
9.670
1528
100(2)
1.674
5.153
1240
100(2)
1.478
4.025
1432
Dcalcd. [gcm–3]
μ [mm–1]
F(000)
θ range [°]
Limiting indices
2.70–26.00
–9ՅhՅ9
–1ՅkՅ35
–1ՅlՅ14
6241
2.12–29.51
–11ՅhՅ11
–12ՅkՅ12
–31ՅlՅ32
33326
1.96–26.37
–9ՅhՅ9
–38ՅkՅ38
–15ՅlՅ15
19467
2.04–26.38
–9ՅhՅ9
–32ՅkՅ31
–22ՅlՅ22
24803
Reflections collected
Independent reflections, Rint
Observed reflections [IϾ2σ(I)]
Data/restraints/parameters
R1, wR2 [IϾ2σ(I)][a]
5229, 0.0347
4713
5229/0/289
0.0337, 0.0838
0.0390, 0.0872
1.080
4640, 0.0426
4122
4640/0/342
0.0258, 0.0603
0.0307, 0.0627
1.087
9910, 0.0558
8270
9910/44/540
0.0486, 0.0981
0.0612, 0.1028
1.032
6480, 0.0626
4550
6480/74/368
0.0501, 0.0976
0.0811, 0.1080
1.112
R1, wR2 (all data)[a]
GoF (on F2)[a]
Flack parameter
0.02(1)
2.544/–2.426
Largest diff peak/hole [eÅ–3]
1.226/–1.448
1.104/–0.817
1.365/–2.991
[a] R = Σ(||Fo| – |Fc||)/Σ|Fo|. wR2 = {Σ[w(Fo – Fc ) ]/Σ[w(Fo2)2]}1/2. GoF = {Σ[w(Fo – Fc )(n – p)]}1/2
.
2
2 2
2
2
precipitate. After hot filtration and rinsing with hot toluene, the
solvent was removed in vacuo. Recrystallization of the green solid
from a mixture of chloroform/heptane gave the dark green products
in 43–69% yields.
34.5, 34.7, 40.0, 47.9, 56.4, 66.2, 66.3 (CH2, CH3, CMe3), 122.9,
124.4, 124.7, 139.2, 144.3, 151.4 (Ar) ppm. C20H34Cl2NO2ReS
(609.66): calcd. C 39.40, H 5.62, N 2.30; found C 39.43, H 5.47, N
2.19. IR (KBr): ν = 2952, 2866, 1456, 1256, 956, 914, 854 cm–1. EI-
˜
MS: m/z (%) = 609 (38) [M+].
Synthesis of [ReOCl2(ONO)] (1): The compound was prepared ac-
cording to the general procedure by employing KONO (39 mg,
Synthesis of [ReOCl2(ONNMe)] (3): The compound was prepared
0.10 mmol) in toluene (20 mL) and [ReOCl3(OPPh3)(SMe2)] according to the general procedure by employing KONNMe
1
(67 mg, 0.10 mmol) in toluene (30 mL) to give 1 (36 mg, 62%). H (59 mg, 0.16 mmol) in toluene (20 mL) and [ReOCl3(OPPh3)-
NMR (CDCl3): δ = 1.26 (s, 18 H, CH3), 2.54 (d, J = 13.7 Hz, 1 H,
(SMe2)] (113 mg, 0.17 mmol) in toluene (30 mL) to give 3 (63 mg,
CH2), 3.27 (m, 1 H, CH2), 3.33 (s, 3 H, CH3), 3.53 (s, J = 13.9 Hz, 60%). 1H NMR (CDCl3): δ = 1.25 (s, 9 H, CH3), 1.26 (s, 9 H,
1 H, CH2), 4.33 (dd, J = 9.6, 3.5 Hz, 1 H, CH2), 4.45 (s, 3 H, CH3), CH3), 2.52 (s, 3 H, CH3), 2.97 (m, 1 H, CH2), 3.21 (s, 3 H, CH3),
4.50 (m, 1 H, CH2), 5.11 (d, J = 13.8 Hz, 1 H, CH2), 6.89 (d, J = 3.30 (m, 2 H, CH2), 3.51 (d, J = 13.6 Hz, 1 H, CH2), 3.54 (s, 3 H,
1.8 Hz, 1 H, Ar), 7.27 (m, 1 H, Ar) ppm. 13C NMR (CDCl3): δ = CH3), 3.55 (m, 1 H, CH2), 5.20 (d, J = 14.1 Hz, 1 H, CH2), 6.83
29.3, 31.4, 34.6, 34.8, 56.0, 62.5, 66.3, 70.5, 85.6 (CH2, CH3, (d, J = 1.8 Hz, 1 H, Ar), 7.24 (d, J = 2.0 Hz, 1 H, Ar) ppm. 13C
CMe3), 121.6, 124.4, 124.9, 138.6, 144.0, 152.1 (Ar) ppm.
C19H32Cl2NO3Re (579.57): calcd. C 39.38, H 5.56, N 2.42; found
NMR (CDCl3): δ = 30.3, 31.4, 34.5, 35.0, 51.3, 55.6, 61.7, 65.3,
66.8, 74.1 (CH2, CH3, CMe3), 121.1, 124.3, 125.0, 138.8, 143.7,
151.7 (Ar) ppm. C20H35Cl2N2O2Re·0.15 OPPh3 (634.36): calcd. C
C 39.20, H 5.57, N 2.21. IR (KBr): ν = 2948, 2864, 1474, 1262,
˜
958, 914, 864 cm–1. EI-MS: m/z (%) = 579 (71) [M+].
42.98, H 5.92, N 4.42; found C 43.05, H 5.79, N 3.72. IR (KBr): ν
˜
= 2948, 1458, 1250, 972, 914, 862 cm–1. EI-MS: m/z (%) = 592 (43)
Synthesis of [ReOCl2(ONS)] (2): The compound was prepared ac-
cording to the general procedure by employing KONS (37 mg,
[M+].
0.10 mmol) in toluene (20 mL) and [ReOCl3(OPPh3)(SMe2)] Synthesis of [ReOCl2(ONNEt)] (4): The compound was prepared
1
(67 mg, 0.10 mmol) in toluene (30 mL) to give 2 (35 mg, 58%). H according to the general procedure by employing KONNEt (61 mg,
NMR (CDCl3): δ = 1.23 (s, 9 H, CH3), 1.24 (s, 9 H, CH3), 1.57 (t,
J = 7.5 Hz, 3 H, CH3), 2.87 (dt, J = 11.8, 4.6 Hz, 1 H, CH2), 3.12 (107 mg, 0.17 mmol) in toluene (30 mL) to give 4 (60 mg, 57%).
(q, J = 7.3 Hz, 2 H, CH2), 3.20 (m, 1 H, CH2), 3.45 (s, 3 H, CH3),
1H NMR (CDCl3): δ = 1.26 (s, 9 H, CH3), 1.29 (s, 9 H, CH3), 1.29
3.48 (m, 1 H, CH2), 3.55 (d, J = 13.9 Hz, 1 H, CH2), 3.73 (d, J = (m, overlapped by s, 3 H, CH3), 1.45 (t, J = 6.5 Hz, 3 H, CH3),
0.16 mmol) in toluene (20 mL) and [ReOCl3(OPPh3)(SMe2)]
12.2 Hz, 1 H, CH2), 5.32 (d, J = 13.7 Hz, 1 H, CH2), 6.89 (s, 1 H,
2.64 (m, 1 H, CH2), 3.12 (m, 1 H, CH2), 3.25 (s, 3 H, CH3), 3.35
(m, 5 H, CH2), 3.47 (m, 1 H, CH2), 3.87 (m, 1 H, CH2), 5.23 (d, J
Ar), 7.22 (s, 1 H, Ar) ppm. 13C NMR (CDCl3): δ = 13.3, 29.7, 31.4,
5724
www.eurjic.org
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2010, 5718–5727

Oxidorhenium(V) Complexes with Phenol-Based Ligands
= 14.0 Hz, 1 H, CH2), 6.81 (s, 1 H, Ar), 7.27 (s, 1 H, Ar) ppm. 13
C
Synthesis of [ReOCl2(ONOO)] (9): The compound was prepared
NMR (CDCl3): δ = 9.09, 10.6, 30.6, 31.4, 34.4, 35.1, 52.2, 56.3,
according to the general procedure by employing KONOO (59 mg,
61.0, 66.8, 66.9, 68.0 (CH2, CH3, CMe3), 121.4, 123.8, 125.3, 139.0, 0.15 mmol) in toluene (20 mL) and [ReOCl3(OPPh3)(SMe2)]
143.3, 152.4 (Ar) ppm. C22H39Cl2N2O2Re (620.67): calcd. C 42.57,
(104 mg, 0.16 mmol) in toluene (20 mL) to give 9 (61 mg, 65%).
1H NMR (CDCl3): δ = 1.28 (s, 18 H, CH3), 2.84 (d, J = 14.0 Hz,
1 H, CH2), 3.19 (m, 1 H, CH2), 3.42 (s, 3 H, CH3), 3.45 (m, 1 H,
CH2), 3.75 (m, 2 H, CH2), 3.89 (m, 1 H, CH2), 4.28 (m, 2 H, CH2),
4.45 (m, 1 H, CH2), 4.47 (s, 3 H, CH3), 5.09 (d, J = 14.0 Hz, 1 H,
CH2), 6.88 (d, J = 1.4 Hz, 1 H, Ar), 7.27 (s, 1 H, Ar) ppm. 13C
NMR (CDCl3): δ = 29.3, 31.4, 34.6, 34.8, 58.9, 61.0, 62.5, 64.9,
69.1, 70.1, 85.4 (CH2, CH3, CMe3), 121.7, 124.3, 124.8, 144.0,
152.1, 157.4 (Ar) ppm. C21H36Cl2NO4Re (623.63): calcd. C 40.45,
H 6.33, N 4.51; found C 42.60, H 4.60, N 2.10. IR (KBr): ν =
˜
2946, 1472, 1250, 964, 918, 852 cm–1. EI-MS: m/z (%) = 620 (32)
[M+].
Synthesis of [ReOBr2(ONO)] (5): The compound was prepared ac-
cording to the general procedure by employing KONO (69 mg,
0.20 mmol) in toluene (20 mL) and [ReOBr3(PPh3)2] (193 mg,
1
0.25 mmol) in toluene (30 mL) to give 5 (62 mg, 46%). H NMR
(CDCl3): δ = 1.27 (s, 18 H, CH3), 2.39 (m, 1 H, CH2), 3.34 (m, 4
H, CH3, CH2), 3.48 (d, J = 14.0 Hz, 1 H, CH2), 4.20 (m, 1 H,
CH2), 4.48 (m, 1 H, CH2), 4.53 (s, 3 H, CH3), 5.38 (d, J = 15.3 Hz,
1 H, CH2), 6.87 (s, 1 H, Ar), 7.27 (s, 1 H, Ar) ppm. 13C NMR
(CDCl3): δ = 29.6, 31.6, 34.8, 35.1, 55.9, 62.4, 66.7, 70.4, 84.4 (CH2,
CH3, CMe3), 121.5, 124.5, 125.3, 139.2, 144.4, 152.3 (Ar) ppm.
C19H32Br2NO3Re (668.48): calcd. C 34.14, H 4.82, N 2.10; found
H 5.82, N 2.25; found C 40.12, H 5.53, N 2.17. IR (KBr): ν =
˜
2942, 1468, 1440, 1266, 958, 918, 858 cm–1. EI-MS: m/z (%) = 623
(14) [M+].
Synthesis of [ReOCl2(ONSS)] (10): The compound was prepared
according to the general procedure by employing KONSS (63 mg,
0.14 mmol) in toluene (20 mL) and [ReOCl3(OPPh3)(SMe2)]
(94 mg, 0.14 mmol) in toluene (20 mL) to give 10 (44 mg, 46%).
1H NMR (CDCl3): δ = 1.22 (s, 9 H, CH3), 1.25 (s, 9 H, CH3), 1.29
(t, J = 7.4 Hz, 3 H, CH3), 1.59 (t, J = 7.4 Hz, 3 H, CH3), 2.60 (q,
J = 7.3 Hz, 2 H, CH2), 2.88 (t, J = 12.0 Hz, 1 H, CH2), 3.12 (m, 3
H, CH2), 3.25 (m, 2 H, CH2), 3.53 (m, 2 H, CH2), 3.66 (d, J =
13.6 Hz, 1 H, CH2), 3.75 (d, J = 11.7 Hz, 1 H, CH2), 4.05 (dt, J =
10.8, 4.7 Hz, 1 H, CH2), 5.42 (d, J = 13.4 Hz, 1 H, CH2), 6.88 (d,
J = 1.8 Hz, 1 H, Ar), 7.22 (d, J = 2.0 Hz, 1 H, Ar) ppm. 13C NMR
(CDCl3): δ = 14.1, 15.2, 26.9, 27.4, 29.7, 30.3, 34.6, 34.8, 41.1, 50.1,
62.3, 66.5, 66.9 (CH2, CH3, CMe3), 122.6, 124.6, 124.7, 139.3,
144.4, 151.0 (Ar) ppm. C23H40Cl2NO2ReS2 (683.80): calcd. C
C 33.90, H 4.63, N 2.12. IR (KBr): ν = 2962, 2864, 1474, 1436,
˜
1262, 1020, 968, 918, 864 cm–1. EI-MS: m/z (%) = 669 (27) [M+].
Synthesis of [ReOBr2(ONS)] (6): The compound was prepared ac-
cording to the general procedure by employing KONS (75 mg,
0.20 mmol) in toluene (20 mL) and [ReOBr3(PPh3)2] (193 mg,
1
0.25 mmol) in toluene (30 mL) to give 6 (60 mg, 43%). H NMR
(CDCl3): δ = 1.21 (s, 9 H, CH3), 1.25 (s, 9 H, CH3), 1.27 (m, 3 H,
CH3), 2.83 (dt, J = 11.3, 3.1 Hz, 1 H, CH2), 2.99 (m, 2 H, CH2),
3.17 (dt, J = 11.5, 2.2 Hz, 1 H, CH2), 3.25 (s, 3 H, CH3), 3.49 (d,
J = 13.9 Hz, 1 H, CH2), 3.70 (m, 2 H, CH2), 5.62 (d, J = 13.8 Hz,
1 H, CH2), 6.84 (s, 1 H, Ar), 7.21 (s, 1 H, Ar) ppm. 13C NMR
(CDCl3): δ = 13.5, 29.7, 31.4, 34.5, 34.8, 47.1, 57.4, 58.1, 65.2, 66.7
(CH2, CH3, CMe3), 122.5, 124.5, 124.8, 139.5, 144.5, 151.0 (Ar)
ppm. C20H34Br2NO2ReS (698.56): calcd. C 34.39, H 4.91, N 2.01;
40.40, H 5.90, N 2.05; found C 40.84, H 5.89, N 2.06. IR (KBr): ν
˜
= 2926, 1448, 1254, 960, 900, 856 cm–1. EI-MS: m/z (%) = 683 (1)
[M+].
found C 34.61, H 4.97, N 1.91. IR (KBr): ν = 2960, 1442, 1244,
˜
968, 914, 854 cm–1. EI-MS: m/z (%) = 699 (46) [M+].
Synthesis of [ReOCl2(ONNNEt)] (11): The compound was pre-
pared according to the general procedure by employing KONNNEt
(64 mg, 0.14 mmol) in toluene (20 mL) and [ReOCl3(OPPh3)-
(SMe2)] (92 mg, 0.14 mmol) in toluene (30 mL) to give 11 (51 mg,
Synthesis of [ReOBr2(ONNMe)] (7): The compound was prepared
according to the general procedure by employing KONNMe
(51 mg, 0.15 mmol) in toluene (20 mL) and [ReOBr3(OPPh3)-
(SMe2)] (118 mg, 0.15 mmol) in toluene (30 mL) to give 7 62 mg
(61%). 1H NMR (CDCl3): δ = 1.24 (s, 9 H, CH3), 1.26 (s, 9 H,
CH3), 2.51 (s, 3 H, CH3), 2.93 (d, J = 12.5 Hz, 1 H, CH2), 3.19 (s,
3 H, CH3), 3.30 (m, 2 H, CH2), 3.52 (d, J = 14.5 Hz, 1 H, CH2),
3.57 (s, 3 H, CH3), 3.57 (s, 1 H, CH2), 5.40 (d, J = 14.2 Hz, 1 H,
CH2), 6.84 (s, 1 H, Ar), 7.23 (s, 1 H, Ar) ppm. 13C NMR (CDCl3):
δ = 30.3, 31.4, 34.5, 35.0, 51.1, 55.4, 61.5, 64.5, 66.8, 73.2 (CH2,
CH3, CMe3), 121.1, 124.5, 125.0, 138.9, 143.9, 151.3 (Ar) ppm.
C20H35Br2N2O2Re·0.09OPPh3 (706.56): calcd. C 36.75, H 5.19, N
1
52%). H NMR (CDCl3): δ = 1.25 (s, 18 H, CH3), 1.25 (m, 12 H,
CH3), 2.65 (m, 1 H, CH2), 2.95 (m, 4 H, CH2), 3.68 (m, 8 H, CH2),
3.62 (d, J = 13.9 Hz, 1 H, CH2), 3.83 (m, 1 H, CH2), 3.90 (m, 1
H, CH2), 3.96 (m, 1 H, CH2), 5.14 (d, J = 13.8 Hz, 1 H, CH2),
6.87 (d, J = 2.0 Hz, 1 H, Ar), 7.25 (d, J = 2.1 Hz, 1 H, Ar) ppm.
13C NMR (CDCl3): δ = 9.43, 10.5, 10.7, 30.5, 31.4, 34.5, 35.0, 48.3,
48.5, 52.5, 62.2, 62.7, 65.9, 67.8 (CH2, CH3, CMe3), 121.4, 124.5,
125.1, 138.8, 144.1, 152.3 (Ar) ppm. C27H50Cl2N3O2Re (705.82):
calcd. C 45.95, H 7.14, N 5.95; found C 44.99, H 7.02, N 5.59. IR
(KBr): ν = 2938, 1468, 1248, 968, 914, 852 cm–1. EI-MS: m/z (%)
˜
3.96; found C 36.83, H 4.71, N 2.98. IR (KBr): ν = 2948, 1472,
˜
= 705 (3) [M+].
1248, 1116, 962, 862, 856 cm–1. EI-MS: m/z (%) = 682 (29) [M+].
Synthesis of [ReOBr2(ONNEt)] (8): The compound was prepared
Synthesis of [ReOBr2(ONOO)] (12): The compound was prepared
according to the general procedure by employing KONNEt (53 mg,
according to the general procedure by employing KONOO (52 mg,
0.14 mmol) in toluene (20 mL) and [ReOBr3(OPPh3)(SMe2)] 0.13 mmol) in toluene (20 mL) and [ReOBr3(OPPh3)(SMe2)]
(113 mg, 0.14 mmol) in toluene (30 mL) to give 8 (68 mg, 69%).
(110 mg, 0.14 mmol) in toluene (20 mL) to give 12 (57 mg, 62%).
1H NMR (CD2Cl2): δ = 1.24 (s, 9 H, CH3), 1.27 (s, 9 H, CH3),
1H NMR (CDCl3): δ = 1.27 (s, 9 H, CH3), 1.28 (s, 9 H, CH3), 2.90
1.27 (m, overlapped by s, 3 H, CH3), 1.43 (t, J = 7.2 Hz, 3 H, CH3), (m, 1 H, CH2), 3.14 (m, 1 H, CH2), 3.43 (s, 3 H, CH3), 3.61 (m, 4
2.61 (m, 1 H, CH2), 3.05 (m, 1 H, CH2), 3.17 (s, 3 H, CH3), 3.37 H, CH2), 3.96 (d, J = 13.8 Hz, 1 H, CH2), 4.21 (m, 1 H, CH2),
(m, 6 H, CH2), 3.94 (m, 1 H, CH2), 5.35 (d, J = 14.3 Hz, 1 H, 4.29 (m, 1 H, CH2), 4.54 (s, 3 H, CH3), 5.24 (d, J = 13.7 Hz, 1 H,
CH2), 6.86 (s, 1 H, Ar), 7.28 (s, 1 H, Ar) ppm. 13C NMR (CD2Cl2): CH2), 6.88 (s, 1 H, Ar), 7.26 (s, 1 H, Ar) ppm. 13C NMR (CDCl3):
δ = 10.1, 11.5, 30.8, 31.7, 34.6, 35.5, 53.2, 56.5, 61.5, 66.5, 67.3,
67.4 (CH2, CH3, CMe3), 122.1, 124.9, 125.7, 139.5, 144.7, 152.2 (CH2, CH3, CMe3), 122.0, 124.6, 124.8, 138.6, 144.2, 152.4 (Ar)
(Ar) ppm. C22H39Br2N2O2Re (709.57): calcd. C 37.24, H 5.54, N ppm. C21H36Br2NO4Re (712.53): calcd. C 35.40, H 5.09, N 1.97;
δ = 29.4, 31.4, 34.4, 34.5, 59.1, 59.5, 62.2, 64.0, 69.1, 70.2, 85.0
3.95; found C 37.00, H 5.06, N 3.85. IR (KBr): ν = 2952, 2898,
found C 35.50, H 4.96, N 1.96. IR (KBr): ν = 2947, 1452, 1263,
˜
˜
1444, 1238, 974, 914, 854 cm–1. EI-MS: m/z (%) = 710 (17) [M+].
960, 856 cm–1. EI-MS: m/z (%) = 713 (12) [M+].
Eur. J. Inorg. Chem. 2010, 5718–5727
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5725

N. C. Mösch-Zanetti et al.
FULL PAPER
[14]
[15]
W. A. Herrmann, J. Organomet. Chem. 1995, 500, 149–174.
J. Rudolph, L. K. Reddy, J. P. Chiang, K. B. Sharpless, J. Am.
Chem. Soc. 1997, 119, 6189–6190.
G. M. Lobmaier, G. D. Frey, D. E. Dewhurst, E. Herdtweck,
W. A. Herrmann, Organometallics 2007, 26, 6290–6299.
A. Deloffre, S. Halut, L. Salles, J.-M. Brégeault, J. R. Gregorio,
B. Denise, H. Rudler, J. Chem. Soc., Dalton Trans. 1999, 2897–
2898.
A. Sachse, N. C. Mösch-Zanetti, G. Lyashenko, J. W. Wielandt,
K. Most, J. Magull, F. Dall’Antonia, A. Pal, R. Herbst-Irmer,
Inorg. Chem. 2007, 46, 7129–7135.
S. Dinda, M. G. B. Drew, R. Bhattacharyya, Catal. Commun.
2009, 10, 720–724.
A. Schröckeneder, P. Traar, G. Raber, J. Baumgartner, F. Belaj,
N. C. Mösch-Zanetti, Inorg. Chem. 2009, 48, 11608–11614.
J. J. Kennedy-Smith, K. A. Nolin, H. P. Gunterman, F. D. To-
ste, J. Am. Chem. Soc. 2003, 125, 4056–4057.
K. A. Nolin, R. W. Ahn, F. D. Toste, J. Am. Chem. Soc. 2005,
127, 12462–12463.
Synthesis of [ReOBr2(ONSS)] (13): The compound was prepared
according to the general procedure by employing KONSS (55 mg,
0.12 mmol) in toluene (20 mL) and [ReOBr3(OPPh3)(SMe2)]
(101 mg, 0.13 mmol) in toluene (20 mL) to give 13 (42 mg, 49%).
1H NMR (CDCl3): δ = 1.20 (s, 9 H, CH3), 1.25 (s, 9 H, CH3), 1.28
(m, 3 H, CH3), 1.58 (t, J = 7.4 Hz, 3 H, CH3), 2.60 (q, J = 7.4 Hz,
2 H, CH2), 2.91 (t, J = 12.3 Hz, 1 H, CH2), 3.03 (m, 2 H, CH2),
3.22 (m, 3 H, CH2), 3.52 (m, 1 H, CH2), 3.72 (m, 2 H, CH2), 3.74
(d, J = 13.6 Hz, 1 H, CH2), 4.12 (m, 1 H, CH2), 5.63 (d, J =
13.7 Hz, 1 H, CH2), 6.87 (d, J = 1.8 Hz, 1 H, Ar), 7.22 (d, J =
[16]
[17]
[18]
2.0 Hz, 1 H, Ar) ppm. 13C NMR (CDCl3): δ = 14.1, 15.2, 26.9, [19]
27.4, 29.0, 29.7, 30.3, 31.5, 34.6, 40.6, 47.8, 62.4, 65.8 (CH2, CH3,
CMe3), 122.4, 124.7, 124.8, 139.5, 144.6, 150.7 (Ar) ppm.
C23H40Br2NO2ReS2 (772.70): calcd. C 35.75, H 5.22, N 1.81; found
[20]
[21]
C 36.03, H 5.23, N 1.81. IR (KBr): ν = 2922, 1438, 1238, 958, 910,
˜
856 cm–1.
[22]
[23]
[24]
Synthesis of [ReOBr2(ONNNEt)] (14): The compound was pre-
pared according to the general procedure by employing KONNNEt
(56 mg, 0.12 mmol) in toluene (20 mL) and [ReOBr3(OPPh3)-
(SMe2)] (99 mg, 0.13 mmol) in toluene (20 mL) to give 14 (51 mg,
55%). 1H NMR (CDCl3): δ = 1.23 (s, 9 H, CH3), 1.25 (s, 9 H,
CH3), 1.42 (t, J = 6.7 Hz, 12 H, CH3), 2.64 (m, 1 H, CH2), 3.12
(m, 2 H, CH2), 3.33 (m, 8 H, CH2), 3.41 (m, 1 H, CH2), 3.70 (d, J
= 13.5 Hz, 1 H, CH2), 3.73 (m, 1 H, CH2), 4.04 (m, 2 H, CH2),
4.42 (dt, J = 10.0 Hz, 1 H, CH2), 5.35 (d, J = 13.6 Hz, 1 H, CH2),
6.92 (s, 1 H, Ar), 7.26 (d, J = 2.0 Hz, 1 H, Ar) ppm. 13C NMR
(CDCl3): δ = 8.90, 8.91, 10.2, 11.2, 30.5, 31.3, 34.6, 35.0, 48.5, 53.3,
59.4, 62.1, 62.5, 65.1, 66.0 (CH2, CH3, CMe3), 120.9, 124.8, 125.2,
139.1, 144.8, 151.0 (Ar) ppm. C27H50Br2N3O2Re (794.72): calcd. C
G. Du, M. M. Abu-Omar, Curr. Org. Synth. 2008, 12, 1185–
1198.
J. B. Packard, J. F. Kronauge, M. W. Brechbiel in Metallophar-
maceuticals II (Eds.: M. J. Clark, P. J. Sadler), Springer Verlag,
Berlin, 1999.
N. S. Venkataramanan, G. Kuppuraj, S. Rajaopal, Coord.
Chem. Rev. 2005, 249, 1249–1268.
[25]
[26]
E. M. McGarrigle, D. G. Gilheany, Chem. Rev. 2005, 105,
1563–1602.
[27]
[28]
A. Fürstner, A. Leitner, Angew. Chem. Int. Ed. 2002, 41, 609.
V. C. Gibson, S. K. Spitzmesser, Chem. Rev. 2003, 103, 283–
316.
C. K. Williams, L. E. Breyfogle, S. K. Choi, W. Nam, V. G.
Young, M. A. Hillmyer, W. B. Tolman, J. Am. Chem. Soc. 2003,
125, 11350–11359.
S. Groysman, E. Sergeeva, I. Goldberg, M. Kol, Inorg. Chem.
2005, 44, 8188–8190.
A. R. F. Cox, V. C. Gibson, E. L. Marshall, A. J. P. White, D.
Yeldon, Dalton Trans. 2006, 5014–5023.
C. A. Huang, C. L. Ho, C. T. Chen, Dalton Trans. 2008, 3502–
3510.
M. E. Judmaier, A. Wallner, G. N. Stipicic, K. Kirchner, J.
Baumgartner, F. Belaj, N. C. Mösch-Zanetti, Inorg. Chem.
2009, 48, 10211–10221.
[29]
40.81, H 6.34, N 5.29; found C 40.20, H 6.23, N 4.78. IR (KBr): ν
˜
= 2946, 1456, 1236, 962, 910, 854 cm–1. EI-MS: m/z (%) = 795 (1)
[M+].
[30]
[31]
[32]
[33]
Catalytic Epoxidation Reaction: The reactions were carried out un-
der an inert gas. Cyclooctene (0.30 g, 2.72 mmol), dibutyl ether
(0.30 g, 2.30 mmol), and the respective rhenium(V) catalyst (2 mol-
%) were dissolved in chloroform (20 mL). The reaction mixture was
heated to 50 °C, whereupon TBHP (1.5 mL, 5.5 m solution in dec-
ane, 8.2 mmol) was added. Prior to GC–MS analyses, aliquot sam-
ples were quenched with MnO2 with subsequent dilution.
[34]
[35]
A. Abufarag, H. Vahrenkamp, Inorg. Chem. 1995, 34, 3279–
3284.
B. D. Sherry, R. N. Loy, F. D. Toste, J. Am. Chem. Soc. 2004,
126, 4510–4511.
[1] J. C. Bryan, R. E. Stenkamp, T. H. Tulip, J. M. Mayer, Inorg.
Chem. 1987, 26, 2283–2288.
[2] E. A. Ison, J. E. Cessarich, N. E. Travia, P. E. Fanwick, M. M.
Abu-Omar, J. Am. Chem. Soc. 2007, 129, 1167–1178.
[3] J. H. Espenson, Coord. Chem. Rev. 2005, 249, 329–341.
[4] J. B. Arterburn, M. C. Perry, Tetrahedron Lett. 1997, 38, 7701–
7704.
[36]
[37]
D. E. Grove, G. J. Wilkinson, J. Chem. Soc. A 1966, 1224–1230.
N. P. Johnson, C. J. L. Lock, G. Wilkinson, Inorg. Synth. 1967,
9, 145–148.
B. L. Wegenhart, M. M. Abu-Omar, Inorg. Chem. 2010, 49,
4741–4743.
R. A. Corbin, E. A. Ison, M. M. Abu-Omar, Dalton Trans.
2009, 15, 2850–2855.
U. Mazzi, F. Refosco, G. Bandoli, M. Nicolini, Transition Met.
[38]
[39]
[40]
[41]
[42]
[43]
[44]
[5] A. Ibdah, W. S. Jenks, J. H. Espenson, Inorg. Chem. 2006, 45,
5351–5357.
Chem. 1985, 10, 121–127.
[6] J. Arias, C. R. Newlands, M. M. Abu-Omar, Inorg. Chem.
2001, 40, 2185–2192.
[7] M. M. Abu-Omar, Chem. Commun. 2003, 2102–2111.
[8] M. M. Abu-Omar, L. D. McPherson, J. Arias, V. M. Béreau,
Angew. Chem. Int. Ed. 2000, 39, 4310–4313.
[9] L. D. McPherson, M. Drees, S. I. Khan, T. Strassner, M. M.
Abu-Omar, Inorg. Chem. 2004, 43, 4036–4050.
[10] J. H. Espenson, Adv. Inorg. Chem. 2003, 54, 157–202.
[11] P. Paraskevopoulou, N. Psaroudakis, S. Koinis, P. Stravo-
poulus, K. Mertis, J. Mol. Catal. A 2005, 240, 27–32.
[12] F. E. Kühn, A. M. Santos, W. A. Herrmann, Dalton Trans.
2005, 2483–2491.
F. E. Kühn, M. U. Rauch, G. M. Lobmaier, G. R. J. Artus,
W. A. Herrmann, Chem. Ber./Recueil 1997, 130, 1427–1431.
W. Hussain, H. J. Banberry, T. A. Hamor, C. J. Jones, J. A.
McCleverty, J. Chem. Soc., Dalton Trans. 1990, 657–661.
S. M. Harben, P. D. Smith, R. L. Beddoes, D. Collison, C. D.
Garner, J. Chem. Soc., Dalton Trans. 1997, 2777–2784.
E. J. de Souza, V. M. Deflon, A. G. de A. Fernandes, S. S.
Lemos, A. Hagenbach, U. Abram, Inorg. Chim. Acta 2006, 359,
1513–1518.
[45]
[46]
W. A. Herrmann, U. M. Rauch, G. R. J. Artus, Inorg. Chem.
1996, 35, 1988–1991.
L. D. McPherson, M. Drees, S. I. Khan, T. Strassner, M. M.
[13] D. Musumeci, D. Sica, F. Zollo, Curr. Org. Synth. 2005, 2, 1–
20.
Abu-Omar, Inorg. Chem. 2004, 43, 4036–4050.
5726
www.eurjic.org
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2010, 5718–5727

Oxidorhenium(V) Complexes with Phenol-Based Ligands
[47]
[50] G. M. Sheldrick, SHELX97, Programs for Crystal Structure
Analysis, release 97-2, University of Göttingen, Göttingen,
Germany, 1998.
[51] M. Konrad, F. Meyer, K. Heinze, L. Zsolnai, J. Chem. Soc.,
Dalton Trans. 1998, 199–205.
SAINTPLUS, Software Reference Manual, version 6.45,
Bruker-AXS, Madison, WI, 1997–2003.
[48] R. H. Blessing, Acta Crystallogr. A 1995, 51, 33–38; SADABS,
version 2.1, Bruker AXS, 1998.
[49] S. Parkin, B. Moezzi, H. Hope, J. Appl. Crystallogr. 1995, 28,
53–56.
Received: July 14, 2010
Published Online: November 18, 2010
Eur. J. Inorg. Chem. 2010, 5718–5727
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5727