Synthesis, characterisation and catalytic application of oxidorhenium complexes bearing H-spirophosphorane ligands

Article abstract of DOI:10.1002/ejic.201200062

The coordination properties of the H-spirophosphorane ligands HP(OCMe ₂CMe₂O)₂ (L1), HP(OCHMeCHMeO)₂ (L2) and HP(OCH₂CMe₂NH)₂ (L3) towards rhenium have been studied, and the complexes cis-[ReOCl₂{P(OCMe ₂CMe₂O)OCMe₂CMe₂O}pic] (1a), cis- and trans-[ReOCl₂{P(OCMe₂CMe₂O)OCMe ₂CMe₂O}lut] (2a and 2b), cis- and trans-[ReOBr ₂{P(OCMe₂CMe₂O)OCMe₂CMe ₂O}PPh₃] (3a and 3b), [nBu₄N][ReOCl ₃{P(OCMe₂CMe₂O)OCMe₂CMe ₂O}] (4), cis-[ReOCl₂{P(OCHMeCHMeO)OCHMeCHMeO}py] (5), and [ReOCl₃{P(OCH₂CMe₂NH)OCH₂CMe ₂NH₂}] (6) have been prepared. The H-spirophosphoranes coordinate to the rhenium moiety as bidentate, ionic chelating ligands in 1-5 and as a molecular chelating ligand in 6. The chemical compositions of all the complexes were established by spectroscopic methods and the molecular structures of 1a, 2b, 3a, 3b, 5 and 6 were determined by single-crystal X-ray diffraction. It was proved that some of the complexes 1-6 and their previously obtained congeners are very good cocatalyst precursors for the oxidation of aldehydes using molecular oxygen as oxidant and N-hydroxyphthalimide as catalyst. The impact of the structures of the complexes on their catalytic activity was studied. The presence of spirophosphorane ligands in the structures seems to be essential for stabilising the active form of the cocatalyst. Rhenium complexes bearing H-spirophosphorane ligands have been synthesised and employed as cocatalysts for the oxidation of aldehydes with molecular oxygen.

Full text of DOI:10.1002/ejic.201200062

FULL PAPER
DOI: 10.1002/ejic.201200062
Synthesis, Characterisation and Catalytic Application of Oxidorhenium
Complexes Bearing H-Spirophosphorane Ligands
[a]
[a]
[a]
´
Anna Skarz˙ynska,* Miłosz Siczek, and Jarosław M. Sobczak
Keywords: Homogeneous catalysis / Phosphane ligands / Ligand effects / Rhenium / Oxidation
The coordination properties of the H-spirophosphorane li-
gands HP(OCMe2CMe2O)2 (L1), HP(OCHMeCHMeO)2 (L2)
and HP(OCH2CMe2NH)2 (L3) towards rhenium have been
studied, and the complexes cis-[ReOCl2{P(OCMe2-
ionic chelating ligands in 1–5 and as a molecular chelating
ligand in 6. The chemical compositions of all the complexes
were established by spectroscopic methods and the molecu-
lar structures of 1a, 2b, 3a, 3b, 5 and 6 were determined by
single-crystal X-ray diffraction. It was proved that some of
the complexes 1–6 and their previously obtained congeners
are very good cocatalyst precursors for the oxidation of alde-
hydes using molecular oxygen as oxidant and N-hydroxy-
phthalimide as catalyst. The impact of the structures of the
complexes on their catalytic activity was studied. The pres-
ence of spirophosphorane ligands in the structures seems to
be essential for stabilising the active form of the cocatalyst.
CMe2O)OCMe2CMe2O}pic]
(1a),
cis-
and
trans-
[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}lut] (2a and 2b),
cis- and trans-[ReOBr2{P(OCMe2CMe2O)OCMe2CMe2O}-
PPh3] (3a and 3b), [nBu4N][ReOCl3{P(OCMe2CMe2O)-
OCMe2CMe2O}]
(4),
cis-[ReOCl2{P(OCHMeCHMeO)-
OCHMeCHMeO}py] (5), and [ReOCl3{P(OCH2CMe2NH)-
OCH2CMe2NH2}] (6) have been prepared. The H-spirophos-
phoranes coordinate to the rhenium moiety as bidentate,
protected ketals.[6] The same precursor and its chelating
phosphane analogues, dppe and binap, have been found to
exhibit catalytic properties in the oxidation of a range of
sulfides to sulfoxides with urea/hydrogen peroxide.[7] More-
over, bidentate phosphane complexes have been successfully
used in the epoxidation of olefins with hydrogen peroxide
as oxidant.[8] Thus, organic compounds have been oxidised
by using a variety of oxidising reagents. In addition to mo-
lecular oxygen, hydrogen peroxide,[9] alkyl hydroperox-
ides,[2b] peroxy acids[5,10] and many others have also been
used as oxygen atom donors. The use of molecular oxygen,
known as a “green oxidant”, as a source of oxygen seems
to be a major challenge in the manufacturing of chemicals.
In this context, the design of rhenium catalysts suitable
for the aerobic oxidation of aldehydes and alcohols with an
innocuous oxidant has become the object of our research.
Some time ago we succeeded in preparing the phosphite
Introduction
High-valent transition-metal complexes are well known
as excellent catalysts for catalytic oxidation reactions in the
life sciences (e.g. molybdenum enzymes, cytochrome P-450)
and in chemistry.[1] Among these metals, rhenium com-
pounds and complexes have been found to exhibit catalytic
activity in the oxidation of organic compounds and in oxy-
gen atom transfer (OAT) reactions.[2] The most extensively
used catalyst in oxidation reactions is methyltrioxidorhen-
ium (MTO). At present, it is probably the most versatile
catalyst, used not only in the epoxidation of olefins, but
also in the oxidation of sulfides, anilines and triphenylphos-
phanes.[3] However, other rhenium complexes have also
been found to exhibit catalytic activity in oxidation reac-
tions. Mertis and coworkers showed that tetrabutylammo-
nium perrhenate, [nBu4N][ReO4], is a selective catalyst for
the oxidation of primary substituted benzyl alcohols to the
corresponding aldehydes using PhIO as an oxidant.[4] Re-
cently, Pombeiro and coworkers discovered that pyrazole
complexes and their precursor [ReOCl3(PPh3)2] catalyse the
oxidation of ethane and cyclohexane in the presence of mo-
lecular dioxygen.[5] Arterburn and Perry reported the oxi-
dation of secondary alcohols by dimethyl sulfoxide in the
presence of [ReOCl3(PPh3)2] to yield the corresponding
oxidorhenium
POCMe2CMe2OP(OCMe2CMe2O)}]
complexes
[ReOCl3{(OCMe2CMe2O)-
and [ReOCl3-
{P(OMe)3}2] to promote valuable oxygen atom transfer
from dmso to PPh3.[11] Such high-valent complexes are
moisture- and air-stable, convenient for oxidation under
aerobic reaction conditions. Based on our previous work on
H-spirophosphorane ligands in rhenium chemistry,[12] in
this study we focused on the synthesis of oxidorhenium
complexes and their activity in the catalytic aerobic oxi-
dation of aldehydes and alcohols using a system previously
reported by some of us, that is, the organic catalyst NHPI
(N-hydroxyphthalimide) and a vanadium cocatalyst.[13] The
outstanding features of H-spirophosphoranes, their syn-
[a] Faculty of Chemistry, University of Wrocław,
14 F. Joliot-Curie Str., 50-383 Wrocław, Poland
Fax: +48-713282348
E-mail: anna.skarzynska@chem.uni.wroc.pl
Eur. J. Inorg. Chem. 2012, 3331–3341
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3331

A. Skarzyn´ska, M. Siczek, J. M. Sobczak
˙
FULL PAPER
thetic availability and unique electronic properties (π-ac-
ceptor ability of the phosphorus atom and σ-donor ability
of the nitrogen or oxygen atoms) prompted us to extend the
Results and Discussion
In the course of our research project aimed at the synthe-
family of rhenium complexes containing these ligands. Un- sis, characterisation and catalytic application of rhenium
til now, they have been known to coordinate through the complexes with H-spirophosphorane ligands we used three
phosphorus atom as monodentate ligands [PdCl(μ- different ligands: 2,2,3,3,7,7,8,8-octamethyl-1,4,6,9-tet-
[14]
Cl){P(OCMe2CMe2O)OCMe2CMe2OH}]2
or create raoxa-5λ5-phosphaspiro[4.4]nonane [HP(OCMe2CMe2O)2,
monodentate metallophosphorane complexes, for example, L1],[20] meso-2,3,7,8-tetramethyl-1,4,6,9-tetraoxa-5λ5-phos-
[(C6H4O2)2PCo(CO)3(PPh3)][15] and [(C4H6O3)2PNiCl- phaspiro[4.4]nonane [HP(OCHMeCHMeO)2, L2][21] and
(PMe3)2].[16] H-Spirophosphoranes are also capable of coor- 3,3,8,8-tetramethyl-1,6-dioxa-4,9-diaza-5λ5-phosphaspiro-
dinating as bidentate bridging ligands, [PdCl2{μ-P(O- [4.4]nonane [HP(OCH2CMe2NH)2, L3].[22] All of the li-
C6H4O)OCHPhCH2NH2}]6.[17] However, a survey of the gands coordinate to the rhenium centre as heterofunctional,
literature indicated that ligand coordination by bidentate bidentate, chelating P,E ligands (E = N, O) and they were
chelation through P,N or P,O donor atoms appears to be prepared efficiently according to known literature pro-
the most favourable mode of chelation. In addition to the cedures. The molecular rhenium complexes with tetraoxa-
palladium and rhodium complexes [PdCl2{P(OCMe2- spirophosphoranes L1 and L2 were synthesised by the reac-
CMe2O)OCH2CMe2NH2}][18]
and
[Rh(CO)Cl{P- tion of rhenium precursors [ReOX2(OEt)(L)2] (X = Cl, L =
(OC6H4NH)OC6H4NH2}],[19] this coordination propensity pic, lut, py; X = Br, L = PPh3) with two- or three-fold excess
is exhibited by many rhenium analogues.[12] They are of the respective ligand (Scheme 1). The substitution of
known to form
a series of both mono- ([ReOX2- ethoxide and the N-heterocyclic or phosphane ligand L
{P(OCMe2CMe2O)OCMe2CMe2O}py], X = Cl, Br, I) and with the tautomeric deprotonated form of HP(OCMe2C-
dinuclear complexes ([ReOCl{μ-OP(OR)2}{P(OCMe2- Me2O)2 or HP(OCHMeCHMeO)2 afforded complexes that
CMe2O)OCMe2CMe2O}]2, R = Me or CMe2) with chelat- exhibit geometrical cis/trans isomerism with respect to the
ing hydrospirophosphorane HP(OCMe2CMe2O)2. Hence, halogen atoms: cis- and trans-[ReOCl2{P(OCMe2CMe2O)-
as part of our interest in designing new oxidorhenium(V) OCMe2CMe2O}pic] (1a and 1b), cis- and trans-
complexes with spirophosphorane ligands, we were curious [ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}lut] (2a and
to see whether fine-tuning within the structure of the coor- 2b), cis- and trans-[ReOBr2{P(OCMe2CMe2O)OCMe2-
dinated H-spirophosphorane and a sixth ancillary ligand in CMe2O}PPh3]
(3a
and
3b)
and
cis-[ReOCl2-
the complexes can affect their catalytic properties. {P(OCHMeCHMeO)OCHMeCHMeO}py] (5). The pres-
Scheme 1.
3332
www.eurjic.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 3331–3341

Oxidorhenium Complexes
ence of trans-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}- ferent patterns of signals in the aliphatic range, which indi-
pic] (1b) was established by NMR spectroscopy; the cis/ cates nonequivalence of the eight methyl groups of phos-
trans equilibrium, which does not permit the isolation of phorane ligand P(OCMe2CMe2O)OCMe2CMe2O–. Eight
the product in a pure form, was observed. The cis and trans signals of equal intensity are observed at room temperature
isomers of 2 and 3 were successfully isolated from toluene in the 0.57–1.57 ppm range for the cis isomers 1a–3a,
as a result of differences in their solubility. In the case of whereas four signals of equal intensity are manifested for
complex 2, the cis isomer precipitates first upon cooling as the trans isomers 1b–3b. Besides resonances pertaining to
the minor constituent, whereas in the case of 3, the trans the n-butyl group of the [nBu4N]+ cation, four signals at-
isomer precipitates first from the reaction mixture as the tributed to magnetically nonequivalent methyl groups of the
1
major product. Attempts to obtain an iodide analogue of spirophosphorane are also clearly shown in the H NMR
complex 3 following the same reaction procedure were not spectrum of [nBu4N][ReOCl3{P(OCMe2CMe2O)OCMe2-
successful. When [nBu4N][ReOCl4] was treated with an ex- CMe2O}] (4). The spectrum of cis-[ReOCl2{P(OCHMe-
cess of the ligand L1, an anionic complex with the formula CHMeO)OCHMeCHMeO}py] (5) reveals quite a compli-
[nBu4N][ReOCl3{P(OCMe2CMe2O)OCMe2CMe2O}] (4) cated set of signals. There are 10 doublets, partially overlap-
was obtained. In contrast, the use of the ping, in the aliphatic range (1.05–1.58 ppm) arising from 12
HP(OCH2CMe2NH)2 ligand L3 in the reaction with [Re- methyl groups, eight overlapping multiplets (3.47–
OCl3(Me2S)(OPPh3)] made it possible to obtain the com- 4.58 ppm) attributed to 12 CH protons and four multiplets
plex [ReOCl3{P(OCH2CMe2NH)OCH2CMe2NH2}] (6) in the aromatic range (7.6–8.77 ppm) due to the coordi-
with the neutral form of the H-spirophosphorane. All heter- nated pyridine. Three overlapping groups of signals in the
ofunctional ligands composed of a phosphite group and an aliphatic range arising from 12 CH3 and CH protons along
alkoxo or amino group stabilise the rhenium(V) oxidation with four multiplets from ArH protons indicate the pres-
state. The complexes are stable in air and, with the excep- ence of at least two diastereomers of the cis isomer as well
tion of 6, which is a blue colour, they are pink-violet solids. as the existence of the trans isomer. The presence of the
trans isomer in deuteriated dichloromethane solution due
to cis/trans equilibration was anticipated on the basis of our
Spectroscopic Properties
previous studies,[12a] which, for analogous trans complexes,
The IR spectra of complexes 1–6 show several intense [ReOX2{P(OCMe2CMe2O)OCMe2CMe2O}py] (X = Cl, Br,
bands in the region of 900–1000 cm–1. Apart from strong I), showed a long-range 4J(P,H) coupling between the phos-
vibrations attributed to coordinated phosphite ligands, phorus and the hydrogen atom at the α position of the pyr-
1
stretches characteristic of the Re=O bond also exist in the idine ligand. H NMR spectroscopy also made it possible
same region. For complexes 1–5, tentative analysis based to predict the chelating structure of the spirophosphorane
on our previous work made it possible to identify ν(Re=O) L3 in [ReOCl3{P(OCH2CMe2NH)OCH2CMe2NH2}] (6)
stretching vibrations at about 956 cm–1 (Table 1). Similar owing to the presence of two broad doublets at δ = 4.89
vibrations are in the usual range for complexes exhibiting and 6.94 ppm, attributed to the coordinated amine group.
the trans coordination mode, O=Re–O–, for example, The complexation of phosphorus ligands to the rhenium
[ReOCl2(mal)2] (Hmal = maltol) 953 cm–1,[28] [ReOCl- precursor lowers their symmetry and shifts the signals
(PPh3){κ3-(P,O,OЈ)-P(o-C6H4O)2(o-C6H4-OH)}] 960 cm–1,[29] downfield.
[ReO(OEt)Cl2(PEt3)2] 956 cm–1.[30] For 6, the most salient
The coordination of the H-spirophosphorane ligands in
feature apart from the ν(Re=O) band observed at the higher 1–6 results in the 31P{1H} NMR signals (Table 1) being
frequency of 985 cm–1, is the sharp band of medium inten- shifted downfield relative to the signals of the free ligands,
sity seen at 3222 cm–1 and assigned to ν(NH2). This band δ = –39.16, –30.68, –56.7 ppm for L1–L3, respectively. For
confirms the neutral form of the ligand coordination. Curi- the cis isomers of complexes 1a–3a, singlets corresponding
1
ously, the H NMR spectra allow the cis and trans isomers to coordinated phosphorus ligands appear at δ ≈ 85 ppm,
of complexes 1–3 to be distinguished. They exhibit two dif- but for the trans isomers they are shifted downfield to δ ≈
Table 1. 31P{1H} NMR and IR spectroscopic data for complexes 1–6.
Complex
31P{1H} NMR: δ [ppm][a]
IR: ν(Re=O) [cm–1]
cis-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}pic] (1a)
trans-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}pic] (1b)
cis-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}lut] (2a)
trans-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}lut] (2b)
cis-[ReOBr2{P(OCMe2CMe2O)OCMe2CMe2O}PPh3] (3a)
trans-[ReOBr2{P(OCMe2CMe2O)OCMe2CMe2O}PPh3] (3b)
[nBu4N][ReOCl3{P(OCMe2CMe2O)OCMe2CMe2O}] (4)
cis-[ReOCl2{P(OCHMeCHMeO)OCHMeCHMeO}py] (5)
[ReOCl3{P(OCH2CMe2NH)OCH2CMe2NH2}] (6)
86.77
92.64
86.35
92.57
85.30
956
–
956
956
955
955
958
956
985
–6.18[b]
2
87.80 [d, J(P,P) = 582 Hz]
1.68[b] [d, 2J(P,P) = 582 Hz]
85.72
91.13, 91.29, 91.80[c]
60.72
[a] In CD2Cl2. [b] Chemical shifts attributed to the triphenylphosphane phosphorus. [c] Signals attributed to two diastereomers and the
trans isomer.
Eur. J. Inorg. Chem. 2012, 3331–3341
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3333

A. Skarzyn´ska, M. Siczek, J. M. Sobczak
˙
FULL PAPER
92 ppm for 1b and 2b and δ ≈ 88 ppm for 3b. Moreover, data and the details of the X-ray analysis for these com-
the spectra of 3 exhibit an AX pattern, consistent with two plexes are presented in Table 2; selected bond lengths and
magnetically nonequivalent phosphorus atoms. For 3a, the angles are given in Table 3. The molecular structures of the
spectrum reveals two singlets, but for 3b it comprises two complexes are shown in Figures 1–6. The cis complexes 1a
2
doublets with J(P,P) = 582 Hz, which indicates a vertical and 3a crystallise in the orthorhombic space group P212121
coupling of two phosphorus atoms.
as enantiomorphic crystals with Flack parameters of
0.347(4) and –0.014(6), respectively, which indicates a con-
tribution of two enantiomers to the structure of 1a and the
packing of exclusively one enantiomer in the case of 3a.
Crystallographic Studies
The solid-state structures of 1a, 2b, 3a, 3b, 5 and 6 were The trans isomers 2b and 3b crystallise in the monoclinic
determined by X-ray crystallography. The crystallographic space group C2/c, although the molecular constitution of
Table 2. Crystallographic data for complexes 1a, 2b, 3a, 3b, 5 and 6.
1a
2b
3a
3b
5
6·CH2Cl2
Empirical formula
C18H31Cl2NO5PRe C19H33Cl2NO5PRe C30H39Br2O5P2Re C30H39Br2O5P2Re C13H21Cl2NO5PRe C8H19Cl3N2O3PRe·CH2Cl2
Mr
629.51
643.53
887.57
887.57
559.38
599.70
Crystal system
Space group
Crystal size [mm]
Temperature [K]
a [Å]
orthorhombic
P212121
monoclinic
C2/c
orthorhombic
P212121
monoclinic
C2/c
monoclinic
P21/c
monoclinic
P21/c
0.12ϫ0.08ϫ0.03 0.29ϫ0.07ϫ0.03 0.18ϫ0.07 ϫ0.06 0.35ϫ0.25ϫ0.07 0.15ϫ0.10ϫ0.09 0.41ϫ0.11ϫ0.06
120
11.091(3)
11.322(3)
18.491(6)
120
100
100
80
120
21.556(7)
8.408(3)
27.658(9)
100.32(3)
4932(3)
8
11.008(3)
16.421(4)
18.059(5)
18.124(3)
13.685(3)
26.815(6)
102.21(3)
6500(2)
8
8.596(3)
10.020(3)
22.437(7)
100.67(3)
1899.1(11)
4
11.091(5)
15.316(6)
11.700(5)
111.35(3)
1851.1(14)
4
b [Å]
c [Å]
β [°]
V [Å3]
2322.0(12)
4
1.801
3264.4(15)
4
1.806
Z
ρcalcd. [Mgm–3
]
1.733
1.814
1.956
2.152
λ [Å]
0.71073
5.56
1240
0.71073
5.24
2544
0.71073
6.31
1736
0.71073
6.33
3472
0.71073
6.78
1080
0.71073
7.38
1152
μ [mm–1
F(000)
]
θ range [°]
Reflections collected 25467
4.0–37.5
4.7–32.5
31822
3.1–36.8
45951
2.9–36.7
23981
3.2–36.8
23222
2.0–38.5
17299
Unique reflections
7783
6610
7977
7140
5555
5414
R1/wR2 indices[a]
0.030/0.037[b]
0.023/0.043[c]
0.029/0.049[d]
0.021/0.045[e]
0.042/0.062[f]
0.025/0.048[g]
2
2
[a] Calcd. w = 1/[σ2(Fo2) + (aP)2 + bP] in which P = (Fo + Fc )/3. [b] a = 0.005. [c] a = 0.017. [d] a = 0.013. [e] a = 0.025. [f] a = 0.023.
[g] a = 0.017.
Table 3. Selected bond lenghts [Å] and angles [°] for complexes 1a, 2b, 3a, 3b, 5 and 6.[a]
1a
2b
3a
3b
5
6
Re–O1
Re–O2
Re–N
1.697(2)
1.893(2)
2.169(2)
1.696(2)
1.881(1)
2.202(2)
1.702(3)
1.884(3)
1.703(2)
1.884(1)
1.697(2)
1.889(2)
2.167(3)
1.665(2)
Re–N1
Re–P1
Re–P2
Re–X1
Re–X2
Re–X3
2.158(2)
2.372(1)
2.366(1)
2.3644(9)
2.362(1)
2.498(1)
2.6096(7)
2.5827(7)
2.3949(7)
2.5491(8)
2.5679(5)
2.5697(5)
2.364(2)
2.4270(9)
2.3928(9)
2.4233(8)
2.4168(8)
2.417(1)
2.394(0)
2.475(1)
2.381(1)
2.365(1)
O1–Re–O2
O1–Re–N
O1–Re–N1
O2–Re–N
O1–Re–P1
O2–Re–P1
O1–Re–P2
O2–Re–P2
P1–Re–P2
N–Re–P1
N1–Re–P1
O1–Re–X1
O1–Re–X2
O1–Re–X3
O2–Re–X1
O2–Re–X2
167.73(9)
87.81(9)
173.49(6)
97.60(7)
168.4(1)
172.91(7)
167.3(1)
89.3(1)
92.98(9)
89.65(7)
87.17(9)
87.11(7)
82.06(6)
88.83(6)
91.12(6)
82.44(5)
85.6(1)
85.22(9)
83.51(8)
87.2(1)
91.36(6)
81.57(5)
94.81(6)
92.26(5)
173.82(2)
81.45(9)
89.09(9)
89.73(9)
94.99(3)
93.77(6)
171.27(5)
93.85(8)
91.84(6)
162.81(7)
109.47(7)
98.32(7)
99.48(7)
94.28(6)
92.04(6)
91.15(6)
96.96(9)
91.71(9)
90.22(6)
91.41(6)
98.94(9)
96.14(8)
91.32(6)
91.71(6)
89.17(5)
87.98(5)
94.55(8)
90.45(9)
88.73(5)
89.44(5)
92.32(8)
89.44(7)
[a] X = Cl for complexes 1a, 2b, 5 and 6; X = Br for complexes 3a and 3b.
3334
www.eurjic.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 3331–3341

Oxidorhenium Complexes
Figure 1. Molecular structure of cis-[ReOCl2{P(OCMe2CMe2O)-
OCMe2CMe2O}pic] (1a). The thermal displacement elipsoids are
drawn at the 50% probability level. Hydrogen atoms are shown as
small spheres of arbitrary radii.
Figure 4. Molecular structure of trans-[ReOBr2{P(OCMe2CMe2O)-
OCMe2CMe2O}PPh3] (3b). The thermal displacement elipsoids are
drawn at the 50% probability level. Hydrogen atoms are shown as
small spheres of arbitrary radii.
Figure 2. Molecular structure of trans-[ReOCl2{P(OCMe2CMe2O)-
OCMe2CMe2O}lut] (2b). The thermal displacement elipsoids are
drawn at the 50% probability level. Hydrogen atoms are shown as
small spheres of arbitrary radii.
Figure 5. Molecular structure of cis-[ReOCl2{P(OCHMeCHMeO)-
OCHMeCHMeO}py] (5). The thermal displacement elipsoids are
drawn at the 50% probability level. Hydrogen atoms are shown as
small spheres of arbitrary radii.
Figure 3. Molecular structure of cis-[ReOBr2{P(OCMe2CMe2O)-
OCMe2CMe2O}PPh3] (3a). The thermal displacement elipsoids are
drawn at the 50% probability level. Hydrogen atoms are shown as
small spheres of arbitrary radii.
Figure 6. Molecular structure of cis-[ReOCl3P(OCH2CMe2NH)-
OCH2CMe2NH2]·CH2Cl2 (6). The thermal displacement elipsoids
are drawn at the 50% probability level. Hydrogen atoms are shown
as small spheres of arbitrary radii.
3b is isostructural with that of trans-[ReOCl2{P-
(OCMe2CMe2O)OCMe2CMe2O}PPh3].[12b] Note that, in in the P21/c space group and two diastereomers are present
contrast to cis-1a and cis-3a, the cis isomer of 5 crystallises in the crystal lattice.
Eur. J. Inorg. Chem. 2012, 3331–3341
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3335

A. Skarzyn´ska, M. Siczek, J. M. Sobczak
˙
FULL PAPER
The crystal structures of complexes 1–6 reveal that the The Re–P1 bond lengths are in the range observed for com-
spirophosphorane ligands exhibit chelating structures in the plexes with phosphite ligands,[33] whereas the Re–N bond
solid state, which is consistent with previously published lengths of 2.16 or 2.2 Å fall within the usual range pre-
structures of oxidorhenium(V) complexes.[12] The tetraoxa- viously reported for complexes incorporating N-heterocy-
spirophosphorane ligands L1 and L2 in complexes 1–5 co- clic ligands with sp2-hybridised nitrogen atoms. In complex
ordinate as uni-negative chelating ligands as a result of de- 6, the Re–Cl1 distance of 2.475(1) Å is significantly longer
protonation upon complexation, whereas the phosphorane than the two bond lengths of Re–Cl2 [2.381(1) Å] and Re–
ligand HP(OCH2CMe2NH)2 (L3) in complex 6 coordinates Cl3 [2.365(1) Å], which reflects the trans influence of the
as a neutral molecule. The coordination spheres around the oxido ligand. Other bond lengths and angles within the in-
rhenium atoms in all the complexes can be best described ner core show no unusual features, being within the range
as distorted octahedra. The metal centres are incorporated expected based on a comparison with similar rhenium–ox-
into six-membered metallacycles that adopt a twist confor- ido complexes and do not require further discussion.[12]
mation. The five-membered phosphorus cycles adopt an en-
velope conformation. The alkoxy oxygen atoms of the tetra-
Catalytic Studies
oxaspirophosphorane ligands in 1a, 2b, 3a, 3b and 5 occupy
With a well-defined wide range of rhenium complexes
trans positions relative to the oxido ligands, whereas the in hand, we tested their catalytic efficiency in the aerobic
phosphorus atoms coordinate in cis positions building the oxidation of organic compounds. To determine whether the
meridional structural fragment O=Re–O–P. The Re–O1 dis- catalytic properties of the rhenium species are dependent
tances vary from 1.665(2) to 1.703(2) Å and are in the range on the ligand framework around the metal centre, in ad-
expected for rhenium(V) monooxido complexes with dition to the complexes 1–6, their previously obtained con-
[ReO]3+ cores.[31] The idealised distances for rhenium(V) tri- geners were also screened.[12a–12c] The catalytic properties
ple, double and single bonds are considered to be 1.60, 1.76 of rhenium complexes as cocatalyst precursors were tested
and 2.05 Å, respectively.[32] Thus, the Re–O1 bond lengths in the oxidation of alcohols and aldehydes with molecular
indicate strong multiple bond character, whereas the Re–O2 oxygen catalysed by N-hydroxyphthalimide (NHPI). For
distances of approximately 1.88 Å are similar to distances several decades, NHPI in combination with transition-
determined for single bonds. The shortest Re–O1 bond metal complexes of, for example, cobalt[34] or vanadium[35]
length, for complex 6, estimated to be 1.665(2) Å, is re- as cocatalysts has been reported to form effective catalytic
flected in the IR stretching vibration ν(Re=O) at 985 cm–1. systems for the oxidation of organic compounds in which
Table 4. Catalytic activity of rhenium compounds as cocatalyst precursors in the aerobic oxidation of acrolein catalysed by N-hydroxy-
phthalimide (NHPI).[a]
Entry
Cocatalyst
Reaction time [h]
Yield[b] [%]
TON[c]
1
2
3
4
5
6
None
20.6 (18.9)[d]
19.0
32.8 (0)[d]
32.4
7.6
26.6
16.6
7.6
–
–
–
–
–
–
[23a]
[nBu4N]ReO4
[ReOCl3(Me2S)OPPh3][24]
19.0
20.8
18.1
18.1
[ReOCl2(OEt)(pic)2][25]
[ReOCl2(OEt)(lut)2][26]
[ReOBr2(OEt)(PPh3)2][27]
7
8
9
[nBu4N][ReOCl3{P(OCMe2CMe2O)OCMe2CMe2O}] (4)
cis-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}py][12a]
trans-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}py][12a]
cis-[ReOBr2{P(OCMe2CMe2O)OCMe2CMe2O}PPh3] (3a)
trans-[ReOBr2{P(OCMe2CMe2O)OCMe2CMe2O}PPh3] (3b)
trans-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}OPPh3][12b]
trans-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}PPh3][12b]
cis-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}pym][12c]
cis-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}pic] (1a)
cis-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}lut] (2a)
trans-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}lut] (2b)
cis-[ReOBr2{P(OCMe2CMe2O)OCMe2CMe2O}py][12a]
trans-[ReOBr2{P(OCMe2CMe2O)OCMe2CMe2O}py][12a]
trans-[ReOI2{P(OCMe2CMe2O)OCMe2CMe2O}py][12a]
[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}]2(μ-pym)[12c]
cis-[ReOCl2{P(OCHMeCHMeO)OCHMeCHMeO}py] (5)
[ReOCl3{P(OCH2CMe2NH)OCH2CMe2NH2}] (6)
18.5
19.1
19.2
9.3
60.2
68.6
60.9
96.2
316
360
320
505
525
525
525 (49)[d]
525
–
10
11
12
13
14
15
16
17
18
19
20
21
22
23
17.1
100.0
100.0
100.0 (9.3)[d]
100.0
20.6
15.9
7.0 (20.4)[d]
19.6
20.5
20.5
13.6
17.2
18.5
18.2
20.8
17.2
22.8
57.7
51.4
21.9
8.6
100.0
70.1
–
303
270
–
–
525
368
–
18.5
11.4
[a] Reagents and conditions: 0.35 mL (5.25 mmol) acrolein, 24.7 mg (0.15 mmol) NHPI, 0.01 mmol rhenium cocatalyst, 9.65 mL MeCN,
30 °C, 1 atm. O2. [b] The yields of acrylic acid were calculated on the basis of the initial amount of acrolein. [c] Turnover number: mol
ratio of acrylic acid/Re cocatalyst. [d] Data for the reaction in the absence of NHPI are given in parentheses.
3336
www.eurjic.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 3331–3341

Oxidorhenium Complexes
NHPI serves as a catalyst producing PINO· radicals.[36] In meric
complexes
[ReOCl2{P(OCMe2CMe2O)OCMe2-
the absence of a cocatalyst, PINO· is produced in an autox- CMe2O}L] on the yield of acrylic acid. The highest reaction
idation process, but the yield of the oxidation reaction was rates were obtained for cocatalyst precursors with labile li-
low. To assess the scope and limitations of the catalytic re- gands, such as triphenylphosphane and triphenylphosphane
action, we carried out the oxidation of acrolein to acrylic oxide, or weak basic ligands, for example, pyrimidine. The
acid as a model reaction in the presence of a series of oxido- same TON values for complexes incorporating the OPPh3
rhenium(V) complexes as cocatalysts. The acrylic acid and PPh3 ligands (entries 12 and 13) indicate that the com-
yields and turnover numbers (TON) for these reactions are plex
trans-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}-
summarised in Table 4 and Figure 7 presents the course of PPh3][12b] might be smoothly oxidised to the triphenylphos-
oxygen absorption for selected rhenium complexes. Apart phane oxide analogue. Indeed, the 31P NMR spectrum of
from the spirophosphorane complexes, other known oxido- the post-reaction mixture confirms that OPPh3 is present
rhenium(V) precursors were used as cocatalysts in the oxi- in the system. Complexes with firmly coordinated pyridine,
dation of acrolein (entries 2–6). It is easily seen from the [ReOX2{P(OCMe2CMe2O)OCMe2CMe2O}py] (X = Cl, Br,
results that the presence of a coordinated spirophosphorane
ligand has a significant effect on the catalytic process.
Moreover, its structure and the nature of the substituents Table 5. Aerobic oxidation of organic compounds catalysed by
NHPI in the presence of trans-[ReOCl2{P(OCMe2CMe2O)-
within the phosphoro- and metallacycles may play a crucial
role. The best results were obtained for rhenium complexes
OCMe2CMe2O}PPh3][12b] in MeCN.[a]
with the ligand HP(OCMe2CMe2O)2 (L1). Hence, to deter-
mine the relationship between the structural features of the
cocatalyst precursor and the yield of oxidation products, as
well as complexes 1–6, other complexes previously reported
by us and containing the ligand L1 were also probed. The
rhenium complexes tested represent a wide range of struc-
tural types and ancillary ligands. In the course of the stud-
ies we showed the effect of a sixth ligand L in the mono-
Figure 7. Aerobic oxidation of acrolein catalysed by NHPI with
rhenium complexes: 1) none; 2) [nBu4N]ReO4; 3) [nBu4N][ReOCl3-
{P(OCMe2CMe2O)OCMe2CMe2O}]; 4) cis-[ReOCl2{P(OCMe2-
CMe2O)OCMe2CMe2O}py]; 5) trans-[ReOCl2{P(OCMe2CMe2O)-
[a] Reagents and conditions: 5.25 mmol substrate, 24.7 mg
(0.15 mmol) NHPI, 0.01 mmol trans-[ReOCl2{P(OCMe2CMe2O)-
OCMe2CMe2O}PPh3], MeCN (to give total volume of reaction
mixture of 10 mL), 1 atm. O2. [b] The yields of the acids produced
OCMe2CMe2O}py]; 6) trans-[ReOBr2{P(OCMe2CMe2O)OCMe2- were calculated on the basis of the initial amount of substrate. [c]
CMe2O}PPh3];
CMe2O}OPPh3];
CMe2O}PPh3]; 8ЈЈ) reaction catalysed only by complex trans-
[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}PPh3] without NHPI;
9) cis-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}pym] (see cap-
tion to Table 4 for reaction conditions).
7) trans-[ReOCl2{P(OCMe2CMe2O)OCMe2-
8Ј) trans-[ReOCl2{P(OCMe2CMe2O)OCMe2-
Turnover number: mol ratio of product/Re cocatalyst. [d] The
yields of products obtained in the absence of rhenium cocatalyst
are given in parentheses. [e] For benzaldehyde. [f] For cyclohexa-
none. [g] For pentan-2-one. [h] 5% of n-hexanal and 1% of hexyl
hexanoate were also produced. [i] A long induction time (ca. 10 h)
was observed.
Eur. J. Inorg. Chem. 2012, 3331–3341
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3337

A. Skarzyn´ska, M. Siczek, J. M. Sobczak
˙
FULL PAPER
I; Table 4, entries 8, 9, 18–20), were less effective (some of the trans-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}PPh3]
them even exhibit inhibiting properties) and low reaction complex was still catalytically active when, after completion
rates were obtained. The low reaction rates observed may of the reaction, a new portion of substrate (n-hexanal) was
be caused by a stronger bond with the metal ion. The cata- added (Figure 9, B). However, the post-reaction mixtures of
lytic activities of the rhenium complexes with substituted the NHPI catalyst as well as the catalytic system based on
pyridines correlate well with the basicity of the ancillary NHPI/trans-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}-
ligand: the less basic the N-heterocyclic ligand, the more PPh3] showed similar activities. Mechanistic studies of this
effective the cocatalyst (Table 4, entries 8 and 14–16). For catalytic system, especially the nature of the active rhenium
the
trans-[ReOX2{P(OCMe2CMe2O)OCMe2CMe2O}py] species and their role in the mechanism of aldehyde oxi-
series of complexes, the catalytic activity decreases in the dation are under investigation.
order Cl Ͼ Br Ͼ I. The results presented in Table 5 confirm
that catalytic systems based on NHPI and some rhenium
compounds are largely effective in the oxidation of alde-
hydes, but less so in the oxidation of alcohols. The trans-
[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}PPh3][12b] com-
plex appears to be the cocatalyst precursor of choice for the
oxidation of aldehydes.
Whereas the oxidation of acrolein, benzaldehyde or n-
hexanal proceeded under mild conditions at 30 °C with
yields of 100%, the alcohols were oxidised with low conver-
sions or none at all. The positive effect of the cocatalyst
precursor trans-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}-
PPh3] on the yield of the carboxylic acid was spectacular
for acrolein although it is dependent upon the concentra-
tions of NHPI and the rhenium cocatalyst (Figure 8).
Therefore this result permitted us to exclude the hypothesis
of an autoxidation process. Part A of Figure 9 shows the
course of oxygen uptake in the oxidation of the very reac-
tive n-hexanal. Note that the system based on NHPI and
Figure 8. Aerobic oxidation of acrolein catalysed by 1) trans-
Figure 9. A: aerobic oxidation of n-hexanal catalysed by 1) no cata-
2) NHPI, lyst, 2) trans-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}PPh3],
3) NHPI, 4) NHPI and trans-[ReOCl2{P(OCMe2CMe2O)-
[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}PPh3],
3) NHPI and trans-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}-
PPh3] and 4) half the concentrations of NHPI and the rhenium
cocatalyst compared with 3 (see caption to Table 4 for reaction con-
ditions).
OCMe2CMe2O}PPh3]. See caption to Table 5 for reaction condi-
tions. B: catalytic activity of the post-reaction mixtures after adding
5 mmol n-hexanal (full symbols).
3338
www.eurjic.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 3331–3341

Oxidorhenium Complexes
Elemental analyses were performed with a 2400 CHNS Vario EL
III apparatus.
Conclusions
A series of molecular or ionic octahedral oxidorhenium
complexes with H-spirophosphorane ligands have been syn-
thesised and characterised. The presence of phosphorus and
oxygen or nitrogen atoms in the spirophosphoranes implies
that they can coordinate as either κ1-P or κ2-P,E (E = O, N)
ligands. Indeed, contrary to the known palladium complex
bearing tetraoxaspirophosphorane HP(OCMe2CMe2O)2
(L1), in which the ligand coordinates as a neutral, mono-
dentate κ1-P ligand, its rhenium analogues are known to
complex phosphorus compounds in κ2-P,E uni-negative or
neutral chelating forms. Complexes with the formula
[ReOX2{P(OCMe2CMe2O)OCMe2CMe2O}L] [X = Cl, L =
pic, lut (1, 2); X = Br, L = PPh3 (3)] exhibit structural cis/
trans isomerism, as proved by the different aliphatic pat-
terns in the 1H NMR spectra. Furthermore, tetraoxa-
spirophosphorane complexes 1–5 exhibit the meridional
structural arrangement O=Re–O–P, which is characteristic
of this family group. All the complexes have been shown
to successfully cocatalyse the oxidation of aldehydes with
molecular oxygen in the presence of NHPI as free-radical
source and catalyst initiator. The best results were obtained
for complexes incorporating a sixth labile ligand, tri-
phenylphosphane or triphenylphosphane oxide, or a weakly
coordinated heterocyclic base, for example, pyrimidine. In
our opinion, on the basis of the results obtained for the
oxidation of acrolein catalysed by different rhenium com-
plexes, the presence of the spirophosphorane ligand appears
to be an important factor in stabilising the active form of
the rhenium cocatalyst.
Catalytic Oxidation Reactions: Acrolein (Merck, Schuchardt), allyl
alcohol (Ferak), benzyl alcohol (LOBA), benzaldehyde (LOBA),
cyclohexanol (POCh), hexanal (ABCR) were distilled before use.
Acetonitrile (isocratic HPLC grade from Scharlau), N-hydroxy-
phthalimide (Sigma), 2-pentanol (Schuchardt), 1-hexanol (LOBA)
and trans-cinnamaldehyde (Int. Enzymes) were used as received.
The standard conditions for the oxidation of organic substrates
were as follows: organic substrate (ca. 5 mmol), NHPI catalyst
(0.15 mmol), cocatalyst (0.01 mmol) acetonitrile to top up the vol-
ume to 10 cm3 under atmospheric pressure of pure O2. The reac-
tions were carried out at constant volume in a thermostatted glass
reactor equipped with a magnetic stirring bar and connected to a
computer-controlled automatic gas absorption volume measuring
apparatus. The substrate, acetonitrile and NHPI were added to the
reactor under oxygen. Next, a fixed amount of the cocatalyst was
introduced in one portion, immediately after which stirring was
started and the dioxygen absorption was measured. The amount of
oxygen that reacted was calculated from the volume, pressure and
temperature data using the ideal gas equation. Product analysis was
performed with a Hewlett–Packard HP 5890 II series gas chroma-
tograph equipped with a flame ionisation detector and an HP
5971A mass selective detector. An HP-5 25 m capillary column
(25ϫ0.2ϫ0.33 mm) was used in both cases. In some experiments
an HP 1090 II Liquid Chromatograph with an ODS Hypersil col-
umn (10 cmϫ2.1 mm) and an HP 1047A RI detector was used.
The organic acids were determined by titration with a 0.1 n NaOH
solution using a 719 S Titrino (Metrohm) titrator.
Crystal Structure Determination: X-ray diffraction data for com-
plexes cis-[ReOBr2{P(OCMe2CMe2O)OCMe2CMe2O}PPh3] (3a)
and trans-[ReOBr2{P(OCMe2CMe2O)OCMe2CMe2O}PPh3] (3b)
were collected at 100 K with a KM4 diffractometer with CCD Sap-
phire, and for cis-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}pic]
(1a), trans-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}lut] (2b),
[ReOCl3P(OCH2CMe2NH)OCH2CMe2NH2] (6) at 120 K and cis-
[ReOCl2{P(OCHMeCHMeO)OCHMeCHMeO}py] (5) at 80 K
with an Xcalibur PX diffractometer with a CCD Onyx camera and
Mo-Kα radiation (λ = 0.71073 Å). Diffraction data reduction and
analyses were performed by using CrysAlis RED software.[39] All
the structures were solved by direct methods and refined by full-
matrix least-squares techniques on F2 (SHELX).[40]
Experimental Section
General Procedure: Unless otherwise stated, all reactions and ma-
nipulations were performed in dry glassware using standard
Schlenk techniques under nitrogen. The chemicals were purchased
from Sigma–Aldrich and Fluka and used as received. The solvents
were carefully dried and deoxygenated by standard methods.[37] The
ligand precursors 2,2,3,3,7,7,8,8-octamethyl-1,4,6,9-tetraoxa-5λ5-
phosphaspiro[4.4]nonane [HP(OCMe2CMe2O)2, L1],[20] 2,3,7,8-tet-
ramethyl-1,4,6,9-tetraoxa-5λ5-phosphaspiro[4.4]nonane [HP(OCH-
MeCHMeO)2, L2][21] and 3,3,8,8-tetramethyl-1,6-dioxa-4,9-diaza-
5λ5-phosphaspiro[4.4]nonane [HP(OCH2CMe2NH)2, L3][22]were
prepared according to literature methods. [nBu4N][ReOCl4],[23b,23c]
[ReOCl3(Me2S)(OPPh3)],[24] [ReOCl2(OEt)(pic)2],[25] [ReOCl2-
(OEt)(lut)2],[26] [ReOBr2(OEt)(PPh3)2],[27] [ReOCl2(OEt)(py)2],[38]
trans-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}PPh3],[12b] trans-
Non-hydrogen atoms were refined with anisotropic thermal param-
eters. Hydrogen atoms were set in calculated positions and refined
by using a riding model with Uiso(H) = 1.2Ueq(C) and Uiso(H) =
1.5Ueq(O).
Syntheses of the Complexes 1–6
cis-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}pic]
(1a):
2,2,3,3,7,7,8,8-Octamethyl-1,4,6,9-tetraoxa-5λ5-phosphaspiro[4.4]-
nonane HP(OCMe2CMe2O)2 (L1; 0.31 g, 1.17 mmol) was added to
a suspension of trans-[ReOCl2(OEt)(pic)2] (0.18 g, 0.36 mmol) in
toluene (3 cm3). The reaction mixture was heated and stirred for
4 h during which time the starting rhenium compound reacted and
a violet solution was formed. The excess solvent was removed in
vacuo and hexane was added to the residue. This mixture was fil-
tered, washed with hexane and dried to give cis-
[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}pic] (0.11 g, 49%
yield). Single crystals of 1a suitable for X-ray analysis were ob-
[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}OPPh3],[12b]
cis-
[ReOX2{P(OCMe2CMe2O)OCMe2CMe2O}py] (X = Cl, Br),[12a]
trans-[ReOX2{P(OCMe2CMe2O)OCMe2CMe2O}py] (X = Cl, Br,
I),[12a] cis-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}pym] and
[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}]2(μ-pym)[12c]
were
prepared as described previously (pym = pyrimidine, pic = 4-meth-
ylpyridine, lut = 3,5-dimethylpyridine).
IR and FTIR spectra were recorded in KBr or Nujol with a Bruker
113V FTIR spectrometer. H and 31P{1H} NMR spectra were re-
1
1
corded with a Bruker AMX (300 MHz for 1H NMR) or Avance
500 MHz spectrometer (500 MHz for 1H NMR). The chemical
tained by recrystallisation from dichloromethane/diethyl ether. H
NMR (CD2Cl2): δ = 0.89, 0.99, 1.19, 1.33, 1.45, 1.46, 1.54, 1.57 (s,
3
shifts (δ) are given in ppm relative to TMS (1H) and H3PO4 (31P). 24 H, CH3), 2.67 (s, 3 H, CH3), 7.38 (d, J(H,H) = 6.60 Hz, 2 H,
Eur. J. Inorg. Chem. 2012, 3331–3341
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3339

A. Skarzyn´ska, M. Siczek, J. M. Sobczak
˙
FULL PAPER
CH), 8.73 (d, 3J(H,H) = 6.60 Hz, 2 H, CH) ppm. FTIR (Nujol):
ether. 1H NMR (CD2Cl2) : δ = 0.70, 1.41, 1.44, 1.58 (s, 8 H, CH3),
ν
= 149 (w, νRe–P), 229 (s), 246 (vs), 306 (vs, νRe–N, νRe–
7.45 (m, 3 H, CH), 7.76 (m, 2 H, CH) ppm. FTIR (Nujol): ν
=
˜
˜
max
max
Cl) cm–1. IR (KBr): ν
= 925 (vs), 941 (vs), 978 (vs), 1014 (s),
146 (w, νRe–P), 207 (vs), 225 (m), 248 (m, νRe–Cl, νRe–N) cm–1.
˜
max
1140 (s, νC–O–P) cm–1. C18H31Cl2NO5PRe (629.53): calcd. C
34.34, H 4.96, N 2.22; found C 34.33, H 4.79, N 2.32.
IR (KBr): ν
= 926 (vs), 940 (vs), 1019 (s), 1140 (s, νC–O–
˜
max
P) cm–1. C30H39Br2O5P2Re (887.59): calcd. C 40.60, H 4.43; found
C 40.59, H 4.50.
trans-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}pic] (1b): In an
NMR tube, cis-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}pic]
(1a; 0.005 g, 0.008 mmol) was dissolved in CD3CN. The solution
was heated at reflux for 6 h and analysed by 1H and 31P NMR
spectroscopy. The solution proved to be an almost equimolar mix-
ture of cis-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}pic] (1a)
and trans-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}pic] (1b). 1H
NMR (CDCl3): δ = 1.15, 1.42, 1.51, 1.57 (s, 24 H, CH3), 2.57 (s, 3
H, CH3), 7.38 (d, 3J(H,H) = 5.54 Hz, 2 H, CH), 8.72 (m, 2 H,
CH) ppm.
[nBu4N][ReOCl3{P(OCMe2CMe2O)OCMe2CMe2O}] (4): This
complex was prepared analogously to 1a with [nBu4N][ReOCl4]
(0.10 g, 0.17 mmol) and HP(OCMe2CMe2O)2 (L1; 0.13 g,
1
0.49 mmol) as the starting materials (0.10 g, 72% yield). H NMR
3
(CDCl3): δ = 1.12, 1.32, 1.45, 1.52 (s, 6 H, CH3), 0.97 [t, J(H,H)
= 6.84 Hz, 3 H, CH3], 1.42 (br. m, 2 H, CH2), 1.63 (br. m, 2 H,
CH ), 3.26 (br. m, 2 H, CH ) ppm. FTIR (Nujol): νmax = 260 (vs),
˜
2
2
295 (vs, νRe–Cl) cm–1. IR (KBr): ν
= 923 (vs), 940 (vs), 1023
˜
max
(s), 1143 (s, νC–O–P) cm–1. C28H60Cl3NO5PRe (814.32): calcd. C
41.30, H 7.43, N 1.72; found C 40.61, H 7.23, N 1.65.
cis-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}lut] (2a): This
complex was prepared analogously to 1a with trans-[ReOCl2(OEt)-
(lut)2] (0.33 g, 0.62 mmol) and HP(OCMe2CMe2O)2 (L1; 0.35 g,
1.32 mmol) as the starting materials. The crude product 2a precipi-
tated from the reaction mixture as a light-violet solid (0.08 g, 20%
yield). 1H NMR (CD2Cl2): δ = 0.87, 0.99, 1.20, 1.46, 1.47, 1.54,
1.56, 1.57 (s, 24 H, CH3), 2.35 (s, 6 H, CH3), 7.49 (s, 1 H, CH),
cis-[ReOCl2{P(OCHMeCHMeO)OCHMeCHMeO}py] (5): This
complex was prepared analogously to 1a with trans-[ReOCl2(O-
Et)(py)2] (0.33 g, 0.69 mmol) and HP(OCHMeCHMeO)2 (L2;
1
0.41 g, 0.19 mmol) as the starting materials (0.20 g, 53% yield). H
3
NMR (CD2Cl2): δ = 1.05 [d, J(H,H) = 6.38 Hz, 3 H, CH3], 1.09
3
3
[d, J(H,H) = 6.38 Hz, 3 H, CH3], 1.10 [d, J(H,H) = 6.4 Hz, 3 H,
8.55 (s, 2 H, CH) ppm. FTIR (Nujol): ν
= 150 (w, νRe–P), 273
3
˜
max
CH3], 1.16 (m, 9 H, CH3), 1.42 [d, J(H,H) = 6.12 Hz, 3 H, CH3],
(vs), 297 (vs), 311 (vs, νRe–N, νRe–Cl) cm–1. IR (KBr): νmax = 930
1.45 [d, 3J(H,H) = 6.12 Hz, 3 H, CH3], 1.46 [d, 3J(H,H) = 6.18 Hz,
3 H, CH3], 1.51 [d, 3J(H,H) = 6.24 Hz, 3 H, CH3], 1.56 [d, 3J(H,H)
= 6.24 Hz, 3 H, CH3], 1.58 [d, 3J(H,H) = 6.52 Hz, 3 H, CH3], 3.47
(m, 2 H, CH), 3.62 (m, 1 H, CH), 3.71 (m, 1 H, CH), 4.20 (m, 1
H, CH), 4.27 (m, 2 H, CH), 4.36 (m, 1 H, CH), 4.44 (m, 2 H, CH),
4.58 (m, 2 H, CH), 7.60 (tm, 6 H, CH), 7.90 (tm, 3 H, CH), 8.63
˜
(vs), 978 (vs), 1019 (s), 1043 (s, νC–O–P) cm–1. C19H33Cl2NO5PRe
(643.55): calcd. C 35.46, H 5.17, N 2.18; found C 35.73, H 4.96, N
2.10.
trans-[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}lut] (2b): The
toluene mother liquor from the synthesis of 2a was concentrated
3
(m, 4 H, CH), 8.77 [d, J(H,H) = 5.10 Hz, 2 H, CH] ppm. FTIR
and hexane added to yield
a
precipitate of trans-
(Nujol): ν
= 258 (w), 291 (vs), 320 (vs, νRe–P, νRe–N, νRe–
˜
max
[ReOCl2{P(OCMe2CMe2O)OCMe2CMe2O}lut] (2b, 0.17 g, 43%
yield). Single crystals of 2b suitable for X-ray analysis were ob-
Cl) cm–1. IR (KBr): νmax = 923 (vs), 944 (vs), 1017 (m), 1110 (s, νC–
˜
1
O–P) cm–1. C13H21Cl2NO5PRe (559.39): calcd. C 27.73, H 4.05, N
2.42; found C 27.90, H 3.90, N 2.50.
tained by recrystallisation from dichloromethane/diethyl ether. H
NMR (CD2Cl2): δ = 1.17, 1.42, 1.52, 1.57 (s, 24 H, CH3), 2.34 (s,
6 H, CH3), 7.49 (s, 1 H, CH), 8.44 (s, 2 H, CH) ppm. FTIR (Nujol):
[ReOCl3{P(OCH2CMe2NH)OCH2CMe2NH2}] (6): A solution of
3,3,8,8-tetramethyl-1,6-dioxa-4,9-diaza-5λ5-phosphaspiro[4.4]-
nonane HP(OCH2CMe2NH)2 (L3; 0.10 g, 0.48 mmol) in dichloro-
methane (5 cm3) was added dropwise to a suspension of [Re-
OCl3(Me2S)(OPPh3)] (0.3 g, 0.46 mmol) in dichloromethane
(10 cm3). The mixture was stirred for 1 h, generating a greenish-
blue solution. The solution was concentrated to around 5 cm3 and
the same amount of diethyl ether was added to the system. Slow
evaporation of the filtrate in a stream of nitrogen generated blue
crystals of 6 (0.07 g, 30% yield). Single crystals suitable for X-ray
analysis were obtained by recrystallisation from dichloromethane/
ν
= 147 (w, νRe–P), 248 (m), 273 (w), 298 (vs, νRe–N, νRe–
˜
max
Cl) cm–1. IR (KBr): νmax = 930 (vs), 938 (vs), 1024 (s), 1142 (s, νC–
˜
O–P) cm–1. C19H33Cl2NO5PRe (643.55): calcd. C 35.46, H 5.17, N
2.18; found C 35.49, H 4.95, N 2.19; found C 35.43, H 4.84, N
2.21.
cis-[ReOBr2{P(OCMe2CMe2O)OCMe2CMe2O}PPh3] (3a): Con-
tinuous slow evaporation of the mother liquor of 3b allowed the
formation
of
orange-violet
single
crystals
of
cis-
[ReOBr2{P(OCMe2CMe2O)OCMe2CMe2O}PPh3] suitable for X-
ray analysis. 1H NMR (CD2Cl2): δ = 0.57, 0.79, 1.11, 1.15, 1.24,
1.28, 1.46, 1.48 (s, 8 H, CH3), 7.43 (m, 2 H, CH), 7.49 (m, 1 H,
1
diethyl ether. H NMR (CD2Cl2): δ = 1.46, 1.47, 1.53, 1.57 (s, 12
H, CH3), 4.19 [md, 3J(P,H) = 12.2 Hz, 1 H, CH2, 2J(H,H) =
13.1 Hz, CH2], 4.20 [md, 3J(P,H) = 16.7 Hz, 1 H, 2J(H,H) =
CH), 7.77 (m, 2 H, CH) ppm. FTIR (Nujol): ν
= 159 (w, νRe–
˜
max
P), 186 (s), 197 (vs), 250 (s, νRe–Cl, νRe–N) cm–1. IR (KBr): ν
˜
max
3
2
= 926 (vs), 941 (vs), 1019 (s), 1140 (s, νC–O–P) cm–1. C30H39Br2O5-
13.1 Hz, CH2], 4.38 [q, J(P,H) = 34.1 Hz, 1 H, J(H,H) = 8.5 Hz,
CH2], 4.38 [q, 3J(P,H) = 13.7 Hz, 1 H, 2J(H,H) = 8.4 Hz, CH2],
4.68 (m, 1 H, NH), 4.89 (br. d, 1 H, NH2), 6.94 (br. d, 1 H,
P2Re (887.59): calcd. C 40.60, H 4.43; found C 40.67, H 4.24.
trans-[ReOBr2{P(OCMe2CMe2O)OCMe2CMe2O}PPh3] (3b): This
complex was prepared analogously to 1a with HP(OCMe2CMe2-
O)2 (L1; 0.16 g, 0.60 mmol) and trans-[ReOBr2(OEt)(PPh3)2]
(0.28 g, 0.30 mmol) as the starting materials. The reaction mixture
was heated and stirred for 4 h during which time the greenish-gray
rhenium compound reacted and a violet solution appeared. Excess
solvent was removed in vacuo and diethyl ether was added to the
residue. The precipitate of trans-[ReOBr2{P(OCMe2CMe2O)-
OCMe2CMe2O}PPh3] (3b) was filtered, washed with diethyl ether
and dried (0.19 g, 71% yield). Crystals suitable for X-ray analysis
were obtained by recrystallisation from dichloromethane/diethyl
NH ) ppm. FTIR (Nujol): ν
= 150 (w, νRe–P), 261 (m), 314
˜
2
max
(vs), 334 (vs, νRe–N, νRe–Cl) cm–1. IR (Nujol): ν
= 721 (vs),
˜
max
1000 (vs, νC–O–P), 3154 (w), 3222 (m, νNH2), 3416 (s, ν(N–
H) cm–1. C8H19Cl3N2O3PRe (514.78): calcd. C 18.67, H 3.72, N
5.44; found C 18.42, H 3.74, N 5.48.
CCDC-850880 (for 1a), -850881 (for 2b), -850882 (for 3a), -850883
(for 3b), -850884 (for 5) and -850885 (for 6) contain the supplemen-
tary crystallographic data for this paper. These data can be ob-
tained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
3340
www.eurjic.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 3331–3341

Oxidorhenium Complexes
[19] K. N. Gavrilov, A. V. Korostylev, A. I. Polosukhin, O. G. Bon-
darev, A. Yu. Kovalevsky, V. A. Davankov, J. Organomet.
Chem. 2000, 613, 148–158.
[20] D. L. Haire, E. G. Janzen, I. Hrvoic, Magn. Reson. Chem.
1999, 37, 767–773.
Acknowledgments
The authors thank the Ministry of Science and Higher Education
(grant number N N204 028538) for financial support of this research.
[21] D. Bernard, C. Laurenco, R. Burgada, J. Organomet. Chem.
1973, 47, 113–123.
[22] A. V. Korostylev, O. G. Bondarev, K. A. Lyssenko, A. Yu. Kov-
alevsky, P. V. Petrovskii, G. V. Tcherkaev, I. S. Mikhel, V. A.
Davankov, K. N. Gavrilov, Inorg. Chim. Acta 1999, 295, 164–
170.
[1] a) P. R. Ortitz de Montellano (Ed.), Cytochrome P-450 Struc-
ture, Mechanism, and Biochemistry, 2nd ed., Plenum Press, New
York, 1995; b) R. H. Holm, Coord. Chem. Rev. 1990, 100, 183–
221; c) A. A. Shteinman, Russ. Chem. Bull. Int. Ed. 2001, 50,
1795–1810; d) M. M. Abu-Omar, A. Loaiza, N. Hontzeas,
Chem. Rev. 2005, 105, 2227–2252; e) C. C. Romão, F. E. Kuhn,
˝
[23] a) M. Ferrier, P. F. Weck, F. Poineau, E. Kim, A. Stebbins, L.
Ma, A. P. Sattelberger, K. R. Czerwinski, Dalton Trans. 2012,
W. A. Herrmann, Chem. Rev. 1997, 97, 3197–3246.
[2] a) J. H. Espenson, Chem. Commun. 1999, 6, 479–488; b) G. S.
Owens, J. Arias, M. M. Abu-Omar, Catal. Today 2000, 55, 317–
363.
41, 6291–6298; b) T. Lis, B. Jezowska-Trzebiatowska, Acta
˙
Crystallogr., Sect. B 1977, 33, 1248–1250; c) R. Alberto, R.
Schibli, A. Egli, P. A. Schubiger, W. A. Herrmann, G. Artus,
U. Abram, T. A. Kaden, J. Organomet. Chem. 1995, 493, 119–
127.
[3] a) R. Hua, J.-Li Jiang, Curr. Org. Synth. 2007, 4, 151–174; b)
F. E. Kuhn, A. Scherbaum, W. A. Herrmann, J. Organomet.
Chem. 2004, 689, 4149–4164; c) Z. Zhu, J. H. Espenson, J. Mol.
Catal. A 1995, 103, 87–94; d) K. A. Vassell, J. H. Espenson,
Inorg. Chem. 1994, 33, 5491–5498; e) Z. Zhu, J. H. Espenson,
J. Org. Chem. 1995, 60, 1326–1332; f) M. M. Abu-Omar, J. H.
Espenson, J. Am. Chem. Soc. 1995, 117, 272–280; g) F. E.
[24] a) D. E. Grove, G. J. Wilkinson, Chem. Soc. A 1966, 1224–
1230; b) J. C. Bryan, R. E. Stenkamp, T. H. Tulip, J. M. Mayer,
Inorg. Chem. 1987, 26, 2283–2288.
[25] This complex was prepared analogously to [ReOCl2(OEt)(lu)2]
with [ReOCl3(Me2S)(OPPh3)] (0.45 g, 0.69 mmol) and picoline
(0.2 mL, 2.0 mmol) as the starting materials. Yield: 0.13 g,
Kuhn, W. A. Herrmann, Aqueous-Phase Organometallic Catal-
˝
ysis: Concepts and Applications, 2nd ed. (Eds.: B. Cornils, W. A.
Herrmann), Wiley-VCH, Weinheim, Germany, 2005, pp. 488–
498.
1
3
37%. H NMR (CDCl3): δ = 0.97 [t, J(H,H) = 6.90 Hz, 3 H,
CH3], 2.83 (s, 6 H, CH3), 3.71 [q, 3J(H,H) = 6.90 Hz, 2 H,
CH2], 7.37 [br. d, 3J(H,H) = 6.39 Hz, 4 H, CH], 8.72 [br. d,
[4] P. Paraskevopoulou, N. Psaroudakis, S. Koinis, P. Stavro-
poulos, K. Mertis, J. Mol. Catal. A 2005, 240, 27–32.
[5] a) E. C. B. Alegria, M. V. Kirillova, L. M. D. R. S. Martins,
A. J. L. Pombeiro, Appl. Catal. A 2007, 317, 43–52; b) G. S.
Mishra, E. C. B. Alegria, L. M. D. R. S. Martins, J. J. R. Frau-
sto da Silva, A. J. L. Pombeiro, J. Mol. Catal. A 2008, 285, 92–
100.
[6] J. B. Arterburn, M. C. Perry, Org. Lett. 1999, 1, 769–771.
[7] H. Q. N. Gunaratne, M. A. McKervey, S. Feutren, J. Finlay, J.
Boyd, Tetrahedron Lett. 1998, 39, 5655–5658.
3J(H,H) = 6.90 Hz, 4 H, CH] ppm. IR (KBr): ν
= 915 (s,
˜
max
δOCH2), 958 (vs, νRe=O), 1622 (s, νC=N) cm–1.
C14H19Cl2N2O2Re (504.42): calcd. C 33.33, H 3.80, N 5.55;
found C 33.26, H 3.61, N 5.33.
[26] A. Skarzyn´ska, A. M. Trzeciak, A. Gniewek, Acta Crystallogr.,
˙
Sect. E 2011, 67, m1154–m1155.
[27] N. P. Jonson, C. J. L. Lock, G. Wilkinson, J. Chem. Soc. 1964,
1054–1066.
[28] A. G. de A. Fernandes, P. I. da S. Maia, E. J. de Souza, S. S.
Lemos, A. A. Batista, U. Abram, J. Ellena, E. E. Castellano,
V. M. Deflon, Polyhedron 2008, 27, 2983–2989.
[29] R. G. Cavell, R. W. Hilts, H. Luo, R. McDonald, Inorg. Chem.
1999, 38, 897–905.
[8] S. Dinda, M. G. B. Drew, R. Bhattacharyya, Catal. Commun.
2009, 10, 720–724.
[9] a) J. H. Espenson, M. M. Abu-Omar, Adv. Chem. 1997, 253,
99–134; b) F. E. Kuhn, W. A. Herrmann Metal-oxo and metal-
˝
peroxo species in catalytic oxidations (Ed.: B. Meunier),
Springer, Berlin, Heidelberg, 2000; c) R. Bernini, A. Coratti,
G. Fabrizi, A. Goggiamani, Tetrahedron Lett. 2003, 44, 8991–
8994.
[30] K. J. Smith, A. L. Ondracek, N. E. Gruhn, D. L. Lichten-
berger, P. E. Fanwick, R. A. Walton, Inorg. Chim. Acta 2000,
300, 23–31.
[31] W. A. Nugent, J. M. Mayer, Metal–Ligand Multiple Bonds,
Wiley, New York, 1988.
[32] a) S. Das, I. Chakraborty, A. Chakravorty, Polyhedron 2003,
22, 901–907; b) A. Chakravorty, Eur. J. Inorg. Chem. 2005,
4863–4874.
[33] a) S. Bolano, J. Bravo, S. Garcia-Fontán, J. Castro, J. Or-
ganomet. Chem. 2003, 667, 103–111; b) G. Albertin, S. Anton-
iutti, A. Bacchi, G. B. Ballico, E. Bordignon, G. Pelizzi, M.
Ranieri, P. Ugo, Inorg. Chem. 2000, 39, 3265–3279.
[34] a) Y. Ishii, S. Kato, T. Iwahama, S. Sakaguchi, Tetrahedron
Lett. 1996, 37, 4993–4996; b) T. Iwahama, Y. Yoshino, T. Kei-
toku, S. Sakaguchi, Y. Ishii, J. Org. Chem. 2000, 65, 6502–6507.
[35] P. Figiel, J. M. Sobczak, J. Catal. 2009, 263, 167–172.
[36] a) S. Coseri, Catal. Rev. Sci. Eng. 2009, 51, 218–292; b) I. Her-
mans, J. Peeters, P. A. Jacobs, Top. Catal. 2008, 50, 124; c) F.
Recupero, C. Punta, Chem. Rev. 2007, 107, 3800–3842; d) Y.
Ishii, S. Sakaguchi, Catal. Today 2006, 117, 105–113.
[37] D. D. Perrin, W. L. F. Armarego, Purification of Laboratory
Chemicals, 3rd ed., Pergamon Press, Oxford, 1998.
[10] T.-Fu Wang, C.-C. Hwu, Y.-S. Wen, J. Organomet. Chem. 2004,
689, 411–418.
[11] W. K. Rybak, A. Zagiczek (née Skarzyn´ska), J. Coord. Chem.
˙
1992, 26, 79–82; for complex [ReOCl3{P(OMe)3}2], see: A.
Skarzyn´ska, Ph. D. Thesis, Faculty of Chemistry, University of
˙
Wroclaw, Poland, Wroclaw, 1996.
[12] a) W. K. Rybak, A. Skarzyn´ska, L. Szterenberg, Z. Ciunik, T.
˙
Głowiak, Eur. J. Inorg. Chem. 2005, 4964–4975; b) T. Głowiak,
W. K. Rybak, A. Skarzyn´ska, Polyhedron 2000, 19, 2667–2672;
˙
c) A. Skarzyn´ska, Z. Ciunik, Polyhedron 2009, 28, 336–342; d)
˙
A. Skarzyn´ska, W. K. Rybak, T. Głowiak, Polyhedron 2001, 20,
˙
2667–2674.
[13] P. J. Figiel, J. M. Sobczak, J. J. Ziółkowski, Chem. Commun.
2004, 244–245.
[14] A. Skarzyn´ska, A. M. Trzeciak, M. Siczek, Inorg. Chim. Acta
˙
2011, 365, 204–210.
[15] M. Lattman, S. A. Morse, A. H. Cowley, J. G. Lasch, N. C.
Norman, Inorg. Chem. 1985, 24, 1364–1366.
[16] R. Faw, C. D. Montgomery, S. J. Rettig, B. Shurmer, Inorg. [38] C. J. L. Lock, G. Turner, Can. J. Chem. 1977, 55, 333.
Chem. 1998, 37, 4136–4138.
[39] CrysAlis RED, v.1.171.33.66, Agilent Technologies, UK, Ltd.,
Yarnton, Oxfordshire, England, 2010.
[40] G. M. Sheldrick, Acta Crystallogr., Sect. A 2008, 64, 112–122.
[17] K. N. Gavrilov, I. S. Mikhel, Russ. Chem. Rev. 1996, 65, 225–
247.
[18] A. Skarzyn´ska, A. Gniewek, J. Organomet. Chem. 2011, 696,
Received: January 21, 2012
Published Online: June 6, 2012
˙
2985–2992.
Eur. J. Inorg. Chem. 2012, 3331–3341
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3341