Bidentate phosphinophenol R2P-OH ligands. Oxo and imido Re(V) complexes of 2-diphenylphosphinomethyl-4-methylphenol (P-OH). Crystal structure of ReOCl(P-O)2

Article abstract of DOI:10.1016/S0020-1693(00)00066-9

The PPh₃ ligands were displaced and ReOCl₃(P-OH)₂ (1) was formed when ReOCl₃(PPh₃)₂ and 2 equiv. of the title ligand (P-OH) were refluxed in acetonitrile. In the presence of the proton quencher NEt₃, ligand deprotonation took place and the bis-chelate complex ReOCl(P-O)₂ (2) was isolated. Under similar conditions, ReO(OEt)(P-O)₂ (3) was obtained from ReO(OEt)Cl₂(PPh₃)₂. NMR data are consistent with the trans-O-Re=O-cis-P,P 'twisted' octahedral geometry for these species. The corresponding phenylimido complex Re(NPh)Cl(P-O)₂ (4), similarly prepared from Re(NPh)Cl₃(PPh₃)₂ adopts the trans-O-Re-NPh-trans-P,P arrangement. The structure of 2 was confirmed by X-ray diffraction. The methylene group in the side-arm imparts flexibility to the chelate ring and allows the bond angles to be closer to the ideal octahedral values than in the corresponding diphenylphosphinophenolato compound. The six-membered rings adopt a flattened boat conformation bringing the phenolate unit out of the coordination plane and making the overall van der Waals envelope substantially different from that of the diphenylphosphinophenol-based complex. (C) 2000 Elsevier Science S.A.

Full text of DOI:10.1016/S0020-1693(00)00066-9

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Inorganica Chimica Acta 304 (2000) 52–59
Bidentate phosphinophenol R2PꢀOH ligands. Oxo and imido
Re(V) complexes of 2-diphenylphosphinomethyl-4-methylphenol
(PꢀOH). Crystal structure of ReOCl(PꢀO)2
Fabienne Connac a, Yolande Lucchese a, Marie Gressier a, Miche`le Dartiguenave a,*,
Andre´ L. Beauchamp b
a Laboratoire de Chimie Inorganique, Uni6ersite´ Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex, France
b De´partement de Chimie, Uni6ersite´ de Montre´al, C.P. 6128, Succ. Centre-6ille, Montre´al, Que., Canada H3C 3J7
Received 21 October 1999; accepted 19 January 2000
Abstract
The PPh3 ligands were displaced and ReOCl3(PꢀOH)2 (1) was formed when ReOCl3(PPh3)2 and 2 equiv. of the title ligand
(PꢀOH) were refluxed in acetonitrile. In the presence of the proton quencher NEt3, ligand deprotonation took place and the
bis-chelate complex ReOCl(PꢀO)2 (2) was isolated. Under similar conditions, ReO(OEt)(PꢀO)2 (3) was obtained from
ReO(OEt)Cl2(PPh3)2. NMR data are consistent with the trans-O–ReꢁO-cis-P,P ‘twisted’ octahedral geometry for these species.
The corresponding phenylimido complex Re(NPh)Cl(PꢀO)2 (4), similarly prepared from Re(NPh)Cl3(PPh3)2, adopts the trans-O–
Re–NPh-trans-P,P arrangement. The structure of 2 was confirmed by X-ray diffraction. The methylene group in the side-arm
imparts flexibility to the chelate ring and allows the bond angles to be closer to the ideal octahedral values than in the
corresponding diphenylphosphinophenolato compound. The six-membered rings adopt a flattened boat conformation bringing the
phenolate unit out of the coordination plane and making the overall van der Waals envelope substantially different from that of
the diphenylphosphinophenol-based complex. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Crystal structures; Rhenium complexes; Oxo complexes; Alkoxo complexes; Imido complexes
1. Introduction
examples resulted from hydrogen substitution at the
ortho position of one or more phenyl groups by hy-
droxo [9–12], silyloxo [13], amino [14,15] and thiolato
[16] functions leading in some cases to polydentate
ligands.
As part of our continuous interest in developing
Re(V) complexes for potential application for therapeu-
tic radiopharmaceuticals based on 188Re isotope and for
modeling the technetium derivatives, we have studied
the chelating properties of the bidentate phosphinophe-
nol ligand: Ph2PCH2C6H3(CH3)OH, toward the oxo,
phenylimido and nitrido Re(V) precursors: ReOCl3-
(PPh3)2, Re(NPh)Cl3(PPh3)2 and ReNCl2(PPh3)2. This
ligand belongs to the group of functionalized phosphi-
nes that have been developed by substituting one
phenyl group in PPh3 by alkyl groups bearing acido
[1,2], keto [3,4] or thiolato [5–8] functionalities. Other
Our interest in the bidentate Ph2PCH2C6H3(CH3)OH
ligand lies on the presence of a phenol group bonded to
the phosphorus atom through a CH2 linker. This has,
as a consequence, to lengthen the carbon chain between
the two donor atoms and to give a non-planar preorga-
nization for the ligand. Thus, comparison of the reac-
tivity of this ligand with our previous results on
phosphinophenol will increase our knowledge on the
influence of the steric and electronic effect of these
ligands when they are coordinated to electrophilic
Re(V) centers. Few transition metal complexes bearing
this ligand have been reported [17]. On the other hand,
several technetium [18,19] and rhenium [9–13] oxo
complexes with chelating phosphinophenolato ligands
* Corresponding author. Tel.: +33-5-6155 6121; fax: +33-5-6155
6118.
E-mail address: dartigue@iris.ups-tlse.fr (M. Dartiguenave)
0020-1693/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0020-1693(00)00066-9

F. Connac et al. / Inorganica Chimica Acta 304 (2000) 52–59
53
[Ph2PC6H4O]− have been described but Re-imido com-
pounds remain still scarce. We recently described trans-
PP Re(NPh)X(PꢀO)2 complexes (PꢀO−=diphenyl-
phosphinophenolato and diisopropylphosphinopheno-
lato) [12]. Cis and trans-PP Re-imido compounds were
also reported with the tridentate [PhP(C6H4O)2]2− lig-
and [9].
We describe here the reaction of Ph2PCH2-
C6H3(CH3)OH on the rhenium-oxo, -imido and -ni-
truro precursors. As expected, a difference in the reac-
tivity was observed when compared to diphenyl-
phosphinophenol. While only one Re-oxo species was
obtained in the first case, the reaction of
Ph2PCH2C6H3(CH3)OH gave three Re-oxo species de-
pending on the solvent. On the contrary, several
phenylimido complexes were characterized with phos-
phinophenol while only one species was present here.
Found: C, 52.13; H, 3.95; P, 6.85; Re, 20.48.%. IR
(cm−1, KBr): 960, w(ReꢁO); 3374, w(O–H); 1258, w(C–
OH).
2.2.2. [ReOCl(PꢀO)2] (2)
Solid PꢀOH (310 mg, 1.00 mmol) and ReOCl3(PPh3)2
(421 mg, 0.50 mmol) were suspended in CH3CN (50
ml). NEt3 (0.17 ml, 1.20 mmol) was added and the
reaction mixture was refluxed for 3 h. After cooling, the
brown solution was evaporated in vacuo until a green
precipitate appeared. The solid was filtered off and
recrystallization from CH2Cl2/Et2O yielded 397 mg
(93%) of 2. Anal. Calc. for C40ClH36O3P2Re, 0.5
CH2Cl2: C, 54.61; H, 4.19; P, 6.95; Cl, 7.96; Re, 20.9.
Found: C, 53.58; H, 4.36; P, 6.63; Cl, 8.60; Re, 20.14%.
IR (cm−1, KBr): 960, w(ReꢁO); 1251, w(C–ORe). MS
1
(DCI/NH3): m/z=849 [M+H]+. H NMR (CD2Cl2,
ppm): 2.16 (s, 3H, CH3), 2.25 (s, 3H, CH3), 2.34 (dd,
2
2
1H, PCHAHBPh, JPH=12.4 Hz, JHH=14.8 Hz), 3.69
2
2
2. Experimental
(t, 1H, PCHAHBPh, JPH=14.7 Hz, JHH=14.8 Hz),
3.86 (t, 1H, PCHAHBPh, JPH=13.3 Hz, JHH=13.1
2
2
2
2
2.1. General
Hz), 4.23 (dd, 1H, PCHAHBPh, JPH=10.8 Hz, JHH=
13.1 Hz), 6.30–7.37 (m, 28H, aryl). 31P{1H} (CD2Cl2,
All reactions were carried out under a nitrogen atmo-
sphere using standard Schlenk techniques. ReOCl3-
(PPh3)2 [20], Re(NPh)Cl3(PPh3)2 [21], ReNCl2(PPh3)2
[22] and 2-(diphenylphosphinomethyl)-4-methylphenol
(PꢀOH) [23] were prepared as described in the litera-
ture. The preparation of ReO(OEt)Cl2(PPh3)2 was
adapted from the literature [24] by using NH4ReO4 as
starting material. Infrared (IR) spectra (4000–400
cm−1) were recorded as KBr pellets on a Vector 22
ppm): 10.0 (s), −20.4 (s).
2.2.3. [ReO(OEt)Cl2(PꢀO)2] (3)
To
a suspension of 500 mg (0.59 mmol) of
ReO(OEt)Cl2(PPh3)2 in 40 ml of EtOH were added 361
mg (1.18 mmol) of PꢀOH and 0.2 ml of NEt3. The
mixture was refluxed for 3 h, then cooled to r.t. A green
precipitate was filtered off, washed with Et2O, then
dried in vacuo. Yield: 322 mg (63%). Anal. Calc. for
C42H41O4P2Re: C, 58.73; H, 4.81. Found: C, 58.22; H,
4.47%. IR (cm−1, KBr): 952, w(ReꢁO), 1247 and 1271,
w(C–ORe). MS (FAB\0 MNBA): m/z=858 [M]+.
1H NMR (CD2Cl2, ppm): 1.05 (t, 3H, CH3CH2O,
3JHH=6.9 Hz), 2.12 (s, 3H, CH3Ph), 2.21 (s, 3H,
CH3Ph), 2.21 (dd, 1H, PCHAHBPh, 2JPH=6.6 Hz,
1
Bruker spectrometer. H NMR spectra were obtained
at room temperature (r.t.) in CD2Cl2 on Bruker AMX
400 and WM 250 instruments. The residual solvent
signal (l=5.30 ppm) was used as internal standard and
the chemical shifts are reported with respect to Me4Si.
For the 31P{1H} NMR spectra, the AC 200, AMX 300
and ARX 400 instruments were used and the external
standard was H3PO4 (82% D2O, l=0.0 ppm). Mass
spectra were measured with a NERMAG R10-10 spec-
trometer. Elemental analyses were carried out at the
Laboratoire de Chimie de Coordination du CNRS,
Toulouse, and at the Service Central de Microanalyses
du CNRS, Lyon, France.
2JHH=14.2 Hz), 3.28 (t, 1H, PCHAHBPh, JPH=12.6
2
2
2
Hz, JHH=14.2 Hz), 3.6 (t, 1H, PCHAHBPh, JPH
=
2
13.4 Hz, JHH=13.1 Hz), 4.21 (dd, 1H, PCHAHBPh,
2JPH=9.7 Hz, 2JHH=13.1 Hz), 5.03 (m, 1H,
2
3
4
CH3CHCHDO, JHH=12.2 Hz, JHH=6.9 Hz, JHPe
=
2
3.5 Hz), 5.56 (m, 1H, CH3CHCHDO, JHH=12.2 Hz,
3JHH=6.9 Hz, 4JHPe=0.5 Hz), 6.18–7.57 (m, 28H,
aryl). 31P{1H} (C6D6) l (ppm): −8.3 (s), 2.3 (s).
2.2. Preparati6e work
2.2.4. [Re(NPh)Cl(PꢀO)2] (4)
2.2.1. [ReOCl3(PꢀOH)2] (1)
A
mixture of 840 mg (0.93 mmol) of
ReOCl3(PPh3)2 (421 mg, 0.50 mmol) was added to a
solution of PꢀOH (310 mg, 1.00 mmol) in CH3CN (50
ml). After refluxing for 3 h, the brown solution was
cooled, the brown precipitate was filtered off, and dried
in vacuo. Yield: 441 mg (83%). The brown solid is
insoluble in all common solvents. Anal. Calc. for
C40H38Cl3O3P2Re: C, 52.15; H, 4.16; P, 6.72; Re, 20.21.
Re(NPh)Cl3(PPh3)2, 570 mg (1.86 mmol) of (PꢀOH)
and 0.31 ml (2.20 mmol) of NEt3 in 100 ml of EtOH
was refluxed for 3 h. The brown solid was filtered,
washed with EtOH, and dried in vacuo. Yield: 550 mg
(65%). Anal. Calc. for C46ClH41NO2P2Re: C, 59.84; H,
4.44; N, 1.52. Found: C, 59.26; H, 4.31; N, 1.60%. IR
(cm−1, KBr): 1107, w(ReꢁNPh); 1252 and 1266, w(C–

54
F. Connac et al. / Inorganica Chimica Acta 304 (2000) 52–59
ORe). MS (FAB\0 MNBA): m/z=923 [M]+. 1H
NMR (CD2Cl2, ppm): 2.17 (s, 3H, CH3), 2.22 (s, 3H,
(others). Their isotropic displacement factors Uiso were
adjusted 50% (methyl) or 20% (others) above the value
of the bonded carbon atom. All non-hydrogen atoms
were refined anisotropically. Residuals originating from
a disordered lattice ethanol molecule were observed in
the DF map phased on this model. They were assem-
bled into two individuals and refined isotropically, con-
straints being applied on the C–C and C–O distances
during the refinement. Occupancies converged to 0.80
and 0.20. The general background in the final DF map
CH3), 3.84 (dd, 1H, PCHAHBPh, 2JPH=7.3 Hz, 2JHH
=
13.3 Hz), 3.87 (dd, 1H, PCHAHBPh, 2JPH=5.8 Hz,
2
2JHH=13.3 Hz), 4.01 (dt, 1H, PCHAHBPh, JPH=7.8
2
2
Hz, JHH=13.5 Hz), 4.16 (dd, 1H, PCHAHBPh, JPH
=
4.8 Hz, 2JHH=13.5 Hz), 6.70–7.70 (m, 28H, aryl).
31P{1H} (CD2Cl2) l (ppm): 12.5 (d, 2JPP=306 Hz),
2
−0.9 (d, JPP=306 Hz). The same compound is ob-
tained in CH3CN or toluene.
was within 90.12 e A−3, with highest peaks (1.3 e
,
−3
) and deepest valley (−1.4 e A−3) near the Re
,
A
,
2.3. X-ray crystallography
atom.
Due to the presence of solvent of crystallization
(CH2Cl2), the crystals precipitated from a 1/1 mixture
of CH2Cl2/ether were not used for X-ray determination.
However, suitable green crystals of 2 were obtained by
slow evaporation of an ethanol solution. A specimen
was glued to a glass fiber and the data were collected on
an Enraf–Nonius CAD-4 diffractometer [25] over the
whole sphere (2qmax=140°), corrected for absorption
(NRCVAX package [26], Gaussian integration based
on crystal faces), and averaged. Crystal data and condi-
tions for data collection are summarized in Table 1.
The Re atom was located by the direct methods of
SHELXS-86 [27]. The remaining non-hydrogen atoms
were located from DF syntheses calculated with
SHELXL-93 [28]. Hydrogen atoms were placed at ideal-
ized positions and refined as riding atoms with C–H
3. Results
3.1. Reacti6ity
The reaction of 2-diphenylphosphinomethyl-4-
methylphenol (PꢀOH) on the oxo precursor
ReOCl3(PPh3)2 is complex. Various species were ob-
served depending on the temperature, the solvent used,
and whether the proton quencher NEt3 was present or
not (Scheme 1). In contrast to the similar reactions with
diphenylphosphinophenol [11], bidentate coordination
of PꢀOH did not take place in the absence of NEt3.
Thus, refluxing a 2/1 ratio of PꢀOH and ReOCl3(PPh3)2
in toluene for 3 h resulted in the substitution of both
PPh3 ligands by two monodentate P-coordinated PꢀOH
units. The same reaction conducted in acetonitrile gave
the same brown insoluble material ReOCl3(PꢀOH)2.
An approximatively 1/1 mixture of the twisted trans
and cis-PP ReOCl(PꢀO)2 species was obtained starting
,
distances of 0.97 (methylene), 0.96 (methyl) or 0.93 A
Table 1
Crystal data for ReOCl(PꢀO)2 (2)
Formula
C40H36ClO3P2Re·C2H5OH
894.36
from
a
heated mixture of PꢀOH, NEt3 and
Formula weight
Space group
Unit cell dimensions
ReOCl3(PPh3)2 in the 2/2/1 molar ratio or by reaction
of 2 moles of NEt3 on ReOCl3(PꢀOH)2, in toluene.
They were unambiguously characterized by two AB
spectra: a doublet of doublets at −13.1 and 18.2 ppm
(2JPP=308 Hz) for the trans-PP complex and a broad
doublet at −20.4 and 10.8 ppm (2JPPꢀ0 Hz) for the
cis-PP complex. Recrystallization of this mixture in
CH2Cl2/ether (1/1) gives quantitatively the cis-isomer,
as a green precipitate which crystallizes with CH2Cl2.
Complex 2 was also the unique species obtained in 92%
yield when the reaction was performed in acetonitrile
(Scheme 1). When the reaction was run in EtOH, an
equimolar mixture of cis-PP ReOCl(PꢀO)2 (2) and of
cis-PP oxo-ethoxo ReO(OEt)(PꢀO)2 (3) was obtained, 3
showing the ethanolysis of the Cl ligand.
(
P1
,
a (A)
11.858(4)
12.908(7)
14.175(6)
76.78(4)
86.54(3)
65.24(4)
1917(2)
2
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
V (A )
3
,
Z
T (K)
293(2)
1.550
Cu Ka
1.54056
7.75
Dcalc (g cm−3
Radiation
)
,
u (A)
v (mm−1
)
No. reflections measured
14318
No. independent reflections
No. observed reflections [I\2|(I)]
7284
5674
0.0479
0.0919
0.99
Attempts to isolate the 1:1 complex ReOCl2-
(PꢀO)(PPh3) by refluxing 1 equiv. of PꢀOH with
ReOCl3(PPh3)2 in EtOH for 3 h failed, the disubstituted
oxo-ethoxo compound ReO(OEt)(PꢀO)2 (3) being in-
variably formed [23]. The reduction of NH4ReO4 with 3
equiv. of HCl and 3 equiv. of the phosphine in glacial
a
R
wR2
a
S
a R=ꢀꢁꢁFoꢁ−ꢁFcꢁꢁ/ꢀꢁFoꢁ, wR2=[ꢀw(Fo2−Fc2)2/ꢀ(wFo2)2]1/2
,
S=
[ꢀw(Fo2−Fc2)2/(no. of reflections−no. of parameters)]1/2
.

F. Connac et al. / Inorganica Chimica Acta 304 (2000) 52–59
55
Scheme 1.
Scheme 2.
acetic acid, which is the method used to prepare
3.2. Spectroscopic characterization
ReOCl3(PPh3)2, was no more successful since no clean
reaction was observed.
The brown compound obtained in absence of NEt3
shows a very poor solubility in all common solvents. It
is formulated as ReOCl3(PꢀOH)2 on the basis of the
elemental analysis. The IR spectrum confirms that the
phenol group is not deprotonated, since it includes a
w(O–H) vibration at 3374 cm−1, whereas the w(C–OH)
band at 1258 cm−1 is not appreciably displaced with
respect to the free ligand (1260 cm−1).
The formulae of the oxo bis-chelate complexes Re-
OCl(PꢀO)2 (2) and ReO(OEt)(PꢀO)2 (3) deduced from
microanalyses are confirmed by the mass spectra, where
the parent-ion peaks are found at m/z=849 ([M+H]+
, DCI/NH3) for 2 and 858 ([M]+, FAB+) for 3. Typical
strong ReꢁO stretching vibrations are observed at 960
and 952 cm−1, respectively, in the IR spectra, in the
normal range for these linkages [31]. The w(C–ORe)
In contrast to the complicated reactivity found for
the oxo system, the corresponding phenylimido starting
material Re(NPh)Cl3(PPh3)2 reacted selectively: the
trans-PP isomer Re(NPh)Cl(PꢀO)2 (4) was isolated
quantitatively in the three solvents (ethanol, acetonitrile
and toluene) (Scheme 2).
No reaction occurred when PꢀOH was reacted with
ReNCl2(PPh3)2 in a 2/1 ratio, in presence of NEt3. In
toluene, the starting complex was recovered intact as
indicated by 31P NMR but decomposition occurred in
CH3CN since free PPh3 and OPꢀOH were observed.
Such a result was also obtained with other ligands such
as phosphinophenol, NH(PPh2)2 and NH(XPPh2)2
which all gave oxo and imido Re complexes but no
nitrido species [12,29,30].

56
F. Connac et al. / Inorganica Chimica Acta 304 (2000) 52–59
vibration characteristic of ligand complexation appears
as a broad band at 1251 cm−1 for 2 and as resolved
peaks at 1247 cm−1 and 1271 cm−1 for 3.
−8.3 ppm for 3 are assigned to the Pax atom of the
axial ligand, i.e. the ligand located in a plane containing
the ReꢁO bond. The more strongly bonded Peq atom of
the equatorial ligand, located in the plane perpendicular
to the ReꢁO bond, gives the downfield resonances at
10.0 and 2.3 ppm, respectively. Such differences be-
tween Pax and Peq has been already observed in rhe-
nium–phosphinophenol complexes and attributed to
difference in the bonding [9,10,12].
Inequivalence of the two PꢀO ligands is also evi-
denced from the 1H NMR spectra. Besides the aromatic
protons displaying multiplets in the 6.2–7.6 ppm re-
gion, two singlets are found for the inequivalent ring
methyl groups, at 2.16 and 2.25 ppm for 2, and at 2.12
and 2.21 ppm for 3. Complex 2 exhibits a complex
pattern of four multiplets between 2.2 and 4.3 ppm for
the methylene protons in the metallacycles (3.4 ppm in
the free ligand). A similar pattern is found in the
2.2–4.2 ppm range for 3. They were assigned unam-
biguously by selective irradiation of each of the P
atoms. This pattern originates from the inequivalence
of the two methylene protons (HA and HB) in each of
the non-equivalent ligands, as indicated in Scheme 3.
Each multiplet should actually be a doublet of doublet,
since the doublet due to HA–HB coupling is further
split by H–P coupling. However, in some cases, a
pseudo-triplet is observed, because one of the JH–P
The conformation of complexes 2 and 3 were unam-
biguously deduced from the 31P{1H) NMR spectra. A
structure with the 2 equiv. trans (PꢀO) ligands located
in the equatorial plane, perpendicular to the ReꢁO
bond [10] was ruled out in both cases by the 31P{1H}
NMR data. They show two signals, at 10.0 and −20.4
ppm for 2 and at 2.3 and −8.3 ppm for 3 which
indicate the inequivalence of the two PꢀO. These peaks
exhibit no splitting, but they likely correspond to close
doublets with a JPP coupling constant too small to be
measured, and thus indicate a cis-PP configuration
(Scheme 3). The upfield resonances at −20.4 for 2 and
Scheme 3.
constant is close to JH
The low field multiplets at
–H .
A
B
3.86 and 4.23 ppm becomes two doublets upon decou-
pling the low field phosphorus atom (Peq at 10.0 ppm)
indicating that the protons belong to the equatorial
PꢀO− ligand. Similar decoupling of the upfield phos-
phorus atom Pax (at −20.4 ppm) transforms the multi-
plets at 2.34 and 3.69 ppm into two doublets showing
that this proton belongs to the CH2 group of the axial
ligand. Similar patterns were found after selective phos-
phorus decoupling of 3. In both complexes, the protons
belonging to the methylene group of the equatorial
ligand are more downfield shifted than the protons of
the axial one: 3.86 and 4.23 ppm compared to 2.34 and
3.69 ppm for HA and HB in 2 and 3.60 and 4.21
compared to 2.21 and 3.28 ppm for HA and HB in 3.
This agrees with the better donor capacity of the equa-
torial phosphine compared to the axial one.
Table 2
,
Selected distances (A) and angles (°) in ReOCl(PꢀO)2 complexes with
2-(diphenylphosphinomethyl)phenol (2) and 2-(diphenylphos-
phino)phenol (5)
2
5
Bond distances
Re–P2
Re–P1
Re–O3
Re–O2
2.480(3)
2.446(3)
1.654(7)
1.945(7)
2.015(7)
2.404(3)
2.451(2)
2.443(2)
1.686(4)
2.003(4)
1.987(4)
2.394(2)
Re–O1
Re–Cl
Bond angles
P1–Re–Cl
P2–Re–O1
O2–Re–O3
P1–Re–P2
P1–Re–O1
P1–Re–O2
P1–Re–O3
P2–Re–Cl
P2–Re–O2
P2–Re–O3
O1–Re–Cl
O1–Re–O2
O1–Re–O3
O2–Re–Cl
O3–Re–Cl
C12–O1–Re
C22–O2–Re
161.81(9)
172.0(2)
168.2(3)
93.90(9)
87.5(2)
163.57(7)
162.7(1)
164.3(2)
99.96(6)
80.9(1)
79.8(1)
93.7(2)
90.01(6)
77.7(1)
89.4(2)
85.7(1)
85.5(2)
107.8(2)
89.7(1)
99.5(2)
124.8(4)
127.2(4)
1
Interestingly, the H NMR data for 3 confirms the
stereochemistry of the molecule and the chemical shift
values attributed to the Pax and Peq atoms because of
the presence of the equatorial ethoxy group which
contains inequivalent HC and HD methylene protons.
The methyl group resonates as a triplet at 1.05 ppm
(3JHH=6.9 Hz). Assignment for the inequivalent
methylene hydrogens was confirmed by selective irradi-
ation of the methyl group and of the two phosphorus
atoms. The methylene multiplets occur at 5.03 (HC) and
5.56 (HD) ppm, respectively, as two doublets of quadru-
plet for each proton. They result from a HC–HD cou-
79.6(2)
100.8(2)
95.15(9)
81.7(2)
86.4(2)
81.5(2)
90.8(3)
101.0(3)
86.1(2)
95.5(2)
127.4(6)
137.9(6)

F. Connac et al. / Inorganica Chimica Acta 304 (2000) 52–59
57
ORe) vibration appears as two bands at 1252 and 1266
cm−1, in agreement with the presence of two inequiva-
lent ligands coordinated via the phenolate oxygen. The
31P{1H} NMR spectrum shows doublets at 12.5 and
2
−0.9 ppm with a JP–P coupling constant of 306 Hz. A
trans-PP structure with a phenolate oxygen trans to the
ReꢁNPh bond (Scheme 2) can be reasonably proposed,
considering that the trans OꢁRe–O unit is known to be
very stable and that the crystal structures of all related
phenylimido compounds reported so far show this ar-
1
rangement [12]. The H NMR spectra are also consis-
tent with the presence of inequivalent PꢀO ligands.
However, the proton at 4.01 ppm, attributed to the
CH2 group of the equatorial ligand appears as a dou-
blet of triplets, this indicating a long range phosphorus
coupling with the trans-Pax atom (JH
=4.2
P
–Re–P
eq
Hz), which is often observed in transitiCon metaalx phos-
phine complexes [32].
3.3. X-ray diffraction study
Fig. 1. 1H NMR spectrum of the methylene protons (HC and HD) of
Single-crystal X-ray work on ReOCl(PꢀO)2 (2) confi-
rms the structure deduced from spectroscopic data. As
shown in Fig. 2, the two deprotonated PꢀO ligands act
as chelating agents. The phenolate oxygen of one ligand
lies trans to the ReꢁO bond, making this chelate ring
roughly coplanar with the ReꢁO bond. The other
chelate ring is roughly perpendicular to this direction
and its P donor is cis with respect to the first P atom.
The sixth position is occupied by a chlorine atom.
Thus, this complex adopts the trans-O–ReꢁO cis-P,P
‘twisted’ arrangement reported for related compounds
with diphenylphosphinophenol.
31
the ethanolato ligand in (3) (CD2Cl2, 400.137 MHz, RT): (1)
P
BB
decoupling, (4) no 31P
eq
31
31
decoupling, (2)
decoupling.
P
decoupling, (3)
P
ax
The distances and angles around the Re center are
listed and compared with those of the corresponding
diphenylphosphinophenol complex
5 in Table 2.
Greater flexibility introduced by the methylene group
between the aromatic ring and the PPh2 unit con-
tributes to making the trans angles (mean 167.3°) closer
to 180° than in 5 (mean 163.3°). Also, the bite angles in
2 are closer to 90° (P1–Re–O1=87.5(2) and P2–Re–
O2=81.7(2)° versus 80.9(1) and 77.8(1)°, respectively,
in 5), whereas the repulsion between the bulky PPh2
groups is reduced (P1–Re–P2=93.90(9)° versus
99.96(6)° in 5). In compounds containing an ReꢁO
group, the cis ligands are usually displaced away from
Fig. 2. ORTEP drawing of the ReOCl(PꢀO)2 molecule (2). Ellipsoids
correspond to 40% probability. Hydrogens are omitted for clarity.
pling (2JHH=12.2 Hz) and further couplings with the
terminal methyl group (3JHH=6.9 Hz) and the trans-Pe
the multiple bond. The Re atom indeed lies at 0.23 A
,
from the O–P–P–Cl mean plane, on the ReꢁO side.
However, the ligands do not experience this repulsive
effect to the same extent: the OꢁRe–L angles are large
for P1 (100.8(2)°) and O1 (101.0(3)°), but close to 90°
for P2 (86.4(2)°) and Cl (95.5(2)°).
atom (4JPH =3.5 Hz; JPH =0.5 Hz). This is shown
C
unambiguously by the selecDtive decoupling of the phos-
phorus atoms Pax and Peq (Fig. 1).
The microanalysis and the FAB mass spectrum
([M]+ at 923) are consistent with the Re(NPh)Cl(PꢀO)2
formula proposed for 4. The IR spectrum exhibits the
ReꢁNPh stretching vibrations at 1107 cm−1, in the
typical range for this type of linkage [31]. The w(C–
,
The ReꢁO distance of 1.654(7) A lies on the short
side of the range observed for mono-oxo compounds
[4,33,34]. In contrast with complex 5, the Re–O2 bond
,
trans to the ReꢁO group (1.945(7)A) is shorter than the

58
F. Connac et al. / Inorganica Chimica Acta 304 (2000) 52–59
,
equatorial Re–O1 bond, whose length (2.015(7) A) can
be regarded as normal. This is likely related with the
opening of the Re–O2–C angle (137.9(6)°) compared
with 127.4(6)° for Re–O1–C, since a very short Re–O
when the reaction was performed in ethanol, ethanoly-
sis of the Re–Cl bond occurred for Ph2PCH2C6H3-
(CH3)OH which was not observed for Ph2PC6H4OH.
Reaction of Ph2PCH2C6H3(CH3)OH with the
[ReꢁNPh]3+ precursor gave only the trans-PP isomer
while with Ph2PC6H4OH both cis- and trans-PP iso-
mers were characterized in solution. However, in the
solid state, in both cases, only cis-PP isomers were
isolated for the ReꢁO complexes and trans-PP isomers
for the ReꢁNPh complexes. Comparison of the bond
distances and angles of ReOCl(PꢀO)2 indicates that the
less strained configuration of Ph2PCH2C6H3(CH3)OH
decreases the complex rigidity.
,
distance of 1.915(3) A has recently been reported for
the ReOCl3(L)(PPh3) with 2-(diethylaminomethyl)-4-
methylphenol [34], where the monodentate phenolate
group is almost end-on coordinated (Re–O–C=
166.0(3)°). This would be consistent with a change of
the hybridization state of O2 toward sp, thereby in-
creasing the p character and bond order of Re–O2.
,
However, since short bonds (ꢀ1.95 A) have also been
reported for monodentate phenolate ligands coordi-
nated with Re–O–C angles of ꢀ126° [35], hybridiza-
tion is probably not the only factor involved,
intramolecular inter-ligand non-bonded contacts and
distortion in the coordination polyhedron undoubtedly
making contributions as well.
1
The 31P and H NMR analysis agrees with the solid
state structure already proposed for the Re-oxo and
Re-imino complexes with [PꢀO]− ligands. In all the
cases, the Pax atoms are more shielded indicating that
they donate less electrons to the rhenium center than
the Pe atoms. This agrees with the Re–Pe bond being
shorter than the Re–Pax one.
The two chelate rings have similar conformations,
although the chiralities are opposite. Their conforma-
tion can be described as a very distorted boat, similar
to those noted for Zn2+ and Cu2+ complexes of 2-(di-
alkylaminomethyl)phenols [36]. The pattern of torsion
angles for an idealized boat conformation with all bond
lengths identical and all bond angles equal to 109.5°
would be 60°/0°/−60°/60°/0°/−60° (or the opposite
signs for the other chirality). The sets of values are
−59°/2°/64°/−64°/23°/34° for ligand 1 and 59°/5°/−
53°/50°/−10°/−45° for ligand 2. The rather large
deviations can be ascribed to the disparity in bond
lengths around the ring and the presence of both sp2
(aromatic ring) and sp3 (side arm) hybridized atoms.
The molecules are packed individually in the unit cell
without particular intermolecular interactions. The lat-
tice includes one ethanol solvent molecule per complex,
disordered over two differently populated orientations.
In the most abundant orientation (80%), ethanol is
weakly hydrogen-bonded to a Cl ligand (O4···Cl=
5. Supplementary material
Crystallographic data (lists of atomic positional and
thermal parameters, observed and calculated structure
factor amplitudes) for the structural analysis have been
deposited with the Cambridge Crystallographic Data
Centre, CCDC no. 138937. Copies of the data may be
obtained free of charge from The Director, CCDC, 12
Union Road, Cambridge CB2 1EZ, UK (fax: +44-
1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
Acknowledgements
We are grateful to the French Ministe`re de l’Educa-
tion Nationale, de la Recherche et de la Technologie,
and to the Natural Sciences and Engineering Research
Council of Canada for financial support.
,
3.35(2) A). In the other orientation, it forms a stronger
O–H···O bond with the coordinated phenolate group
,
O1 (O4···O1=2.92(3) A).
4. Concluding remarks
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Ph2PCH2C6H3(CH3)OH
readily
reacts
with
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