Synthesis and chemistry of 2-oxacyclocarbene and 2-cyclovinyl ether ligands supported by the [{MeC(CH2PPh2)3}Re(CO)2] + auxiliary

Article abstract of DOI:10.1016/S0020-1693(02)00931-3

The rhenium(I) cyclovinyl ether complexes [(triphos)Re(CO)₂{C=CHCH₂(CH₂) _nO}]BF₄ [triphos=MeC(CH₂PPh₂)₃; n=1, 2] have been synthesized through the reversible and regio

Full text of DOI:10.1016/S0020-1693(02)00931-3

Inorganica Chimica Acta 339 (2002) 202ꢂ208
/
www.elsevier.com/locate/ica
Synthesis and chemistry of 2-oxacyclocarbene and 2-cyclovinyl ether
ligands supported by the [{MeC(CH2PPh2)3}Re(CO)2]ꢀ auxiliary
Maurizio Peruzzini a,*, Dina Akbayeva a, Claudio Bianchini a,*, Isaac de los Rios a,
Andrea Ienco a, Nicoletta Mantovani b, Lorenza Marvelli b, Roberto Rossi b,*
a Istituto per lo Studio della Stereochimica ed Energetica dei Composti di Coordinazione, ISSECC-CNR, Via J. Nardi 39, 50132 Firenze, Italy
b Dipartimento di Chimica, Universita` di Ferrara, Via Borsari 46, 44100 Ferrara, Italy
Received 7 November 2001; accepted 19 December 2001
Dedicated to Professor Helmut Sigel in recognition of his outstanding contribution to Inorganic and Bioinorganic Chemistry
Abstract
The rhenium(I) cyclovinyl ether complexes [(triphos)Re(CO)2{Cꢀ
have been synthesized through the reversible and regioselective deprotonation of the corresponding 2-oxacyclocarbene complexes
[(triphos)Re(CO)2{ꢀCCH2CH2(CH2)nCH2O}]BF4 (nꢁ1, 2). The structure of the octahedral 2-oxacyclohexylidene complex
[(triphos)Re(CO)2(ꢀCCH2CH2CH2CH2O)]BF4 has been determined by a single-crystal X-ray diffraction analysis.
/
CHCH2(CH2)nO}]BF4 [triphosꢁ
/
MeC(CH2PPh2)3; nꢁ1, 2]
/
/
/
/
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Rhenium; Oxacyclocarbenes; Cyclovinyl ethers; Tripodal ligands; X-ray crystallography
1. Introduction
ily formed that may either lose water intramolecularly
yielding allenylidenes [2ꢂ4] or undergo intramolecular
attack by the OH group at the vinylidene Ca carbon
atom leading to the formation of oxacyclocarbenes [5].
Following the synthetic approach described above,
/
The organometallic support [(triphos)Re(CO)2]ꢀ
[triphosꢁ
generate in situ a variety of h1-organyl ligands con-
nected to the metal by single [1ꢂ4], double [1ꢂ5] or triple
/
MeC(CH2PPh2)3] has been recently used to
/
/
the 2-oxacyclocarbenes [(triphos)Re(CO)2{ꢀ
/
CCH2CH2-
[4] bonds (Scheme 1). Most of these rhenium(I) organ-
ometallics have been prepared through a common
strategy that involves 1-alkynes to vinylidene tautomer-
ization, followed by either intramolecular or intermole-
cular attack at the vinylidene Ca carbon atom.
Intramolecular nucleophilic attacks are generally ob-
served for b-, and g-alkynols as they bear a nucleophilic
substituent capable of intramolecular reactivity [5]. In
contrast, d-alkynols have a low propensity to form
oxygen heterocycles due to the length of the alkyl chain
[5]. Irrespective of the number of carbon spacers
separating the OH group from the 2-carbon atom of
the alkynol, intermediate vinylidene species are primar-
(CH2)nCH(R)O}]BF4 (nꢁ0, 1, 2; RꢁH, Me) have
/
/
been recently isolated by reaction of the appropriate v-
alkynol with the complex [(triphos)Re(CO)2(h2-H2)]ꢀ
(1) that contains a labile H2 ligand (Scheme 2) [5].
However, only the 2-oxa-3-methylcyclopentylidene
complex [(triphos)Re(CO)2(ꢀ/CCH2CH2CH2CH(Me)-
O)]BF4 was authenticated by an X-ray diffraction
analysis [5], while no information was provided on the
chemistry of the 2-oxacyclocarbenes. Aimed at filling
this gap, we describe here the molecular structure of the
2-oxacyclohexylidene complex [(triphos)Re(CO)2(ꢀ
/
CCH2CH2CH2CH2O)]BF4 (3-BF4), and also report on
the reactions of the 2-oxacyclocarbenes with strong
bases. Interestingly, it has been found that the Cb
carbon atom of the oxacyclocarbene ligand undergoes
regioselective and reversible deprotonation to give the
first examples of 2-cyclovinyl ether ligands supported by
the [(triphos)Re(CO)2]ꢀ auxiliary.
* Corresponding authors. Tel.: ꢀ
/
39-55-245 990; fax: ꢀ39-55-247
/
8366
E-mail addresses: peruz@fi.cnr.it (M. Peruzzini), bianchin@fi.cnr.it
(C. Bianchini), mg2@dns.unife.it (R. Rossi).
0020-1693/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 0 - 1 6 9 3 ( 0 2 ) 0 0 9 3 1 - 3

M. Peruzzini et al. / Inorganica Chimica Acta 339 (2002) 202ꢂ
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208
203
Scheme 1.
The crystal structure of 3-BF4 comprises
CCH2CH2CH2CH2O)]ꢀ
cations
and tetrafluoroborate anions with no interspersed
[(triphos)Re(CO)2(ꢀ
/
solvent molecules. Fig. 1 shows a perspective view of
the
cation
CCH2CH2CH2CH2O)]ꢀ; selected bond lengths and
angles are given in Table 1.
[(triphos)Re(CO)2(ꢀ
/
Scheme 2.
The geometry about rhenium can be described as a
slightly distorted octahedron with one facial triphos
ligand and two mutually cis carbonyl groups. A 2-oxa-
cyclohexylidene carbene ligand completes the coordina-
tion sphere. The observed angular distortion (the three
2. Results and discussion
The 16eꢃ fragment [(triphos)Re(CO)2]ꢀ is commonly
generated in solution by treatment of the monohydride
[(triphos)Re(CO)2H] (4) with a slight excess of a strong
protic acid such as HBF4×
OMe2 [6]. The h2-H2 adduct 1
Pꢁ
/
ReꢁP angles show an average value of 85.08 instead
/
of the ideal value of 908) features all octahedral metal
complexes with triphos due to the geometrical con-
/
readily undergoes displacement of the dihydrogen
molecule even by weak nucleophiles, in fact [7]. The
only drawback of this procedure is caused by the
unreacted acid that may react with the nucleophile
leading to decreased yield in the desired rhenium
product. This is certainly the case for alkynols that are
sensitive to protic acids.
The drawback provided by the excess acid can be
overcome by using the neutral rhenium(I) complex
[(triphos)Re(CO)2(OTf)] (5) that contains a weakly
bound triflate ligand, and therefore, can effectively
replace the system 3/Hꢀ to generate the [(triphos)-
Re(CO)2]ꢀ fragment [8]. Following this alternative
procedure, the 2-oxacyclopentylidene [(triphos)Re-
straints imposed by the tripodal structure [1,2,5]. The
˚
C8) is 2.051(10) A and
rhenium carbene distance (Reꢁ
/
compares well with the analogous separations
in
[(triphos)Re(CO)2(ꢀ
CCH2CH2CH2CH(Me)O)]ꢀ
[2.02(2) A] [5], [(triphos)Re(CO)2{ꢀCꢀ
C(H)Ph}]ꢀ
C(OEt)CH3}]ꢀ
[2.071(8) A], [1], and [(triphos)(CO)2Re{C(OMe)CHꢀ
/
˚
/
/
˚
[1.925(6) A], [1], [(triphos)Re(CO)2{ꢀ
/
˚
/
(CO)2(ꢀ
/
CCH2CH2CH2O)]OTf (2-OTf) and the 2-oxa-
cyclohexylidene
[(triphos)Re(CO)2(ꢀCCH2CH2CH2-
/
CH2O)]OTf (3-OTf), have been prepared in almost
quantitative yield by reaction of 5 with 3-butyn-1-ol
and 4-pentyn-1-ol, respectively. Metathetical reaction
with a slight excess of NaBF4 yielded the corresponding
tetrafluoborate salts 2-BF4 and 3-BF4. Recrystallization
Fig. 1. ORTEP drawing of the complex cation [(triphos)Re(CO)2{ꢀ
/
CCH2CH2CH2CH2O}]ꢀ. Only the ipso carbons of the triphos phenyl
substituents are shown for the sake of clarity.
of 3-BF4 from dichloromethaneꢂ/diethyl ether gave
single crystals suited for an X-ray analysis.

204
M. Peruzzini et al. / Inorganica Chimica Acta 339 (2002) 202ꢂ208
/
˚
CH2CH2O)] [2.125(9) A] [9] and in the 2,5-dioxa-
Table 1
˚
Selected bond lengths (A) and angles (8) for [(triphos)Re-
(CO)2{ꢀCCH2CH2CH2CH2O}]BF4 (3-BF4)
cyclopentylidene complex [Br(CO)4Re(ꢀ
/
COCH2CH2O)]
[2.135(8) A] [10], which is consistent with the presence of
˚
three phosphorus donors that increase the p-back
Bond lengths
bonding capability of the metal center. The Reꢁ
/
CO
Re(1)ꢁC(7)
Re(1)ꢁC(6)
Re(1)ꢁC(8)
Re(1)ꢁP(3)
Re(1)ꢁP(1)
Re(1)ꢁP(2)
C(6)ꢁO(2)
C(7)ꢁO(1)
C(8)ꢁO(3)
O(3)ꢁC(12)
C(8)ꢁC(9)
C(9)ꢁC(10)
C(10)ꢁC(11)
C(11)ꢁC(12)
O(3)*ꢁC(12)*
C(8)ꢁO(3)*
C(8)ꢁC(9)*
C(9)*ꢁC(10)*
C(10)*ꢁC(11)*
C(11)*ꢁC(12)*
1.880(11)
1.895(10)
2.051(10)
2.479(2)
2.490(2)
2.498(2)
1.175(11)
1.195(12)
1.401(15)
1.50(2)
˚
and Reꢁ
/
P bond lengths (dReꢁCO
ꢁ
/
1.888 A; dReꢁP
ꢁ
/
ave
ave
˚
2.489 A) are in excellent agreement with those of
rhenium(I) complexes containing the [(triphos)Re-
(CO)2]ꢀ moiety [1,2,5] and do not deserve any addi-
tional comment.
The 2-oxacyclocarbene ligand is disordered and it is
distributed between two positions with occupancy
factors of 67 and 33%, respectively. A flipping angle
1.462(18)
1.54(3)
1.50(3)
around the Re(1)ꢁC(8) vector of about 36.88 discrimi-
/
nates the two conformers suggesting that they are likely
separated by only a negligible difference in energy. In
the most populated conformation, which is presented in
the ORTEP drawing of Fig. 1, an envelope arrangement
1.53(3)
1.49(5)
1.31(3)
1.38(3)
of the hexatomic ring is found with Cꢁ
/
C bond distances
ranging from 1.46 to 1.54 A. This is in line with the
values expected for a CꢁC single bond. In contrast, the
1.36(6)
1.60(5)
1.52(6)
˚
/
Bond angles
less populated conformer exhibits an almost flattened
chair conformation and, as a consequence of the
reduced population, its refinement does not allow us
to discuss in detail the metrical parameters.
The coordination geometry around the carbene car-
bon atom is, in both cases, distorted trigonal planar with
substantial differences between the angles subtended at
C(7)ꢁRe(1)ꢁC(6)
C(7)ꢁRe(1)ꢁC(8)
C(6)ꢁRe(1)ꢁC(8)
C(7)ꢁRe(1)ꢁP(3)
C(6)ꢁRe(1)ꢁP(3)
C(8)ꢁRe(1)ꢁP(3)
C(7)ꢁRe(1)ꢁP(1)
C(6)ꢁRe(1)ꢁP(1)
C(8)ꢁRe(1)ꢁP(1)
P(3)ꢁRe(1)ꢁP(1)
C(7)ꢁRe(1)ꢁP(2)
C(6)ꢁRe(1)ꢁP(2)
C(8)ꢁRe(1)ꢁP(2)
P(3)ꢁRe(1)ꢁP(2)
P(1)ꢁRe(1)ꢁP(2)
O(2)ꢁC(6)ꢁRe(1)
O(1)ꢁC(7)ꢁRe(1)
O(3)ꢁC(8)ꢁC(9)
O(3)ꢁC(8)ꢁRe(1)
C(9)ꢁC(8)ꢁRe(1)
C(8)ꢁO(3)ꢁC(12)
C(8)ꢁC(9)ꢁC(10)
C(11)ꢁC(10)ꢁC(9)
C(10)ꢁC(11)ꢁC(12)
O(3)ꢁC(12)ꢁC(11)
O(3)*ꢁC(8)ꢁC(9)*
O(3)*ꢁC(8)ꢁRe(1)
C(9)*ꢁC(8)ꢁRe(1)
C(8)ꢁO(3)*ꢁC(12)*
C(10)*ꢁC(9)*ꢁC(8)
C(9)*ꢁC(10)*ꢁC(11)*
C(12)*ꢁC(11)*ꢁC(10)*
O(3)*ꢁC(12)*ꢁC(11)*
82.6(4)
83.2(4)
90.4(4)
97.2(3)
93.7(3)
175.9(3)
176.8(3)
95.7(3)
C(8): [Reꢁ
/
C(8)ꢁ
/
C(9) 129.9(8) and O(3)ꢁ
/
C(8)ꢁ
/
C(9)
oxygen bond distance
94.0(3)
85.68(8)
94.8(3)
111.0(10)8]. The carbene carbonꢁ
/
˚
of the more populated conformer is 1.401(15) A, there-
fore, intermediate in length between single and double
174.7(3)
93.9(3)
˚
bonds. A slightly shorter separation [1.376(4) A] has
82.04(8)
87.19(7)
175.1(9)
174.2(10)
111.0(10)
118.3(7)
129.9(8)
122.4(11)
112.0(13)
112.7(17)
113.2(17)
103.6(15)
122(2)
been determined in the manganese derivative II (see
Scheme 3) [11]. Finally, there are no short intermole-
cular contacts and the molecules are held together by
van der Waals forces.
It is worth noticing that several transition-metal
complexes with five-, six- and seven-membered 2-ox-
acycloalkylidene ligands are known [5,11,12] and some
of them have been authenticated by X-ray analyses
[5,11,13ꢂ15]. However, the derivatives containing 2-
/
oxacyclohexylidene ligands are relatively less studied
than those with the 2-oxacyclopentylidene ring
[11,14,15]. To the best of our knowledge, only the
crystal structures of the complexes [(CO)9Mn2-
117.2(15)
118.2(14)
126(3)
117(3)
117(4)
{ꢀ
[14], [Cp?(CO)(PPh3)Mn{ꢀ
(Cp?ꢁC5H4Me) (II) [11] and [Cp(dppe)Ru{ꢀ
/CCH2CH2CH2CH(R)O}]
(Rꢁ/H,
Me)
(I)
/CCH(Me)CH2CMe2CH2O}]
116(3)
111(3)
/
/
Atoms C(9)*, C(10)*, C(11)*, C(12)* and O(3)* refer to the less
abundant conformer.
CHMe}]ꢀ [2.078(10) A] [2]. The Reꢁ
/
C8 distance is
˚
shorter than the analogous separation found in the 2-
oxa-cyclo-pentylidene complex CCH2-
[(CO)5Re(ꢀ
/
Scheme 3.

M. Peruzzini et al. / Inorganica Chimica Acta 339 (2002) 202ꢂ
/
208
205
CCH2CH2CH2CH2O}]PF6 (III) [15] have been reported
so far (Scheme 3).
Complexes 2-OTf and 3-OTf are thermally robust
and did not decompose in solution even in refluxing
THF. In this solvent they did not react with carbon
monoxide or dihydrogen and were not attacked by weak
nucleophiles such as methanol or water. In contrast,
strong bases such as NaOMe or KOBut reacted
immediately with THF solutions of both complexes to
yield the neutral cyclovinyl ether complexes
Scheme 5.
3. Experimental
3.1. General procedure
THF and diethyl ether were purified by distillation
over sodiumꢂbenzophenone under a nitrogen atmos-
[(triphos)Re(CO)2(Cꢀ
/
CHCH2CH2O)]
(6)
and
CHCH2CH2CH2O)] (7) which
/
[(triphos)Re(CO)2(Cꢀ
/
phere. Dichloromethane was refluxed and distilled over
P2O5 under nitrogen. The complex [(triphos)Re-
(CO)2(OTf)] (5) was prepared as described in the
literature [8]. NaOMe was prepared from anhydrous
methanol and freshly cut sodium pieces just before use.
3-Butyn-1-ol and 4-pentyn-1-ol were purchased from
Aldrich, checked by 1H NMR spectroscopy, and used as
received. All reactions and manipulations were routinely
performed under a dry nitrogen atmosphere by using
standard Schlenk-tube techniques. CD2Cl2 for NMR
measurements (Aldrich) was dried over molecular sieves
were isolated in excellent yields (Scheme 4).
While the deprotonation of Fischer-type cyclic ox-
acarbenes with strong bases has already been reported
for osmium [16] and ruthenium complexes [17], 6 and 7
constitute the first example of organorhenium com-
pounds containing a cyclovinyl ether ligand.
Complexes 6 and 7 have been unambiguously char-
acterized by NMR spectroscopy, in particular by 2D
NMR experiments. The AM2 splitting pattern observed
in the 31P NMR spectrum over the temperature range
˚
(4 A), while CF3SO3D (Aldrich) was used as received.
from ꢀ
/
40 to ꢃ70 8C is consistent with the magnetic
/
1H and 13C{1H} NMR spectra were recorded on Varian
VXR 300 or Bruker AC200 spectrometers operating at
299.94 or 200.13 MHz (1H) and 75.42 or 50.32 MHz
(13C), respectively. Peak positions are relative to tetra-
methylsilane and were calibrated against the residual
solvent resonance (1H) or the deuterated solvent multi-
plet (13C). 13C-DEPT and gated 13C{1H} decoupled
NMR experiments were run on the Bruker AC200
spectrometer. 1H,13C-2D HMQC NMR experiments
were recorded on a Bruker AVANCE DRX 500
spectrometer equipped with a 5 mm triple resonance
probe head for 1H detection and inverse detection of the
heteronucleus with no sample spinning. 1H,1H-2D
COSY NMR experiments and 1H,1H-2D NOESY
NMR experiments were conducted on the same instru-
ment in the phase-sensitive TPPI mode. 31P{1H} NMR
spectra were recorded on either the Varian VXR 300 or
Bruker AC200 instruments operating at 121.42 and
81.01 MHz, respectively. Chemical shifts were measured
relative to external 85% H3PO4 with downfield values
taken as positive. Infrared spectra were recorded in KBr
pellets on a Nicolet 510 P spectrometer operating in the
equivalence of the two phosphorus atoms lying trans to
the CO ligands, which suggests that the cyclovinyl ether
ligands rotate freely about the ReꢁCa bond. In keeping
/
with the disappearance of the ‘carbenoid’ character of
Ca upon deprotonation of the CbH2 group, no low-field
resonance was observed in the 13C NMR spectra of 6
and 7 that, conversely, contained the typical signals of
vinylic moieties at 141.4 and 113.1 ppm (6) and 141.2
and 110.4 (7) ppm for the Ca and Cb atoms. DEPT-135
spectra allowed us to unambiguously differentiate the
two vinylic sites.
Interestingly, the vinyl complexes 6 and 7 reacted with
triflic acid (NMR tube tests) to regenerate quantitatively
the oxacarbenes 2-OTf and 3-OTf, which shows the
reversibility of the deprotonation reaction. In order to
prove the regioselectivity of the proton attack, 6 was
reacted in CD2Cl2 with CF3SO3D. As a result, deuter-
ium was selectively incorporated into the Cb position of
the ring. The observed regioselectivity may be accounted
for by a significant contribution of a carbenoid reso-
nance form to describe the electronic structure of 6 and
7 (Scheme 5).
FT mode, or as Nujol mulls on a PerkinꢂElmer 1600
/
series FT IR spectrometer between KBr plates. Ele-
mental analyses were performed with a Carlo Erba
model 1106 elemental analyzer.
3.2. Synthesis of [(triphos)Re(CO)2(ꢀ
/
CCH2CH2CH2O)]OTf (2-OTf)
A slight excess of 3-butyn-1-ol (23 ml, 0.30 mmol) was
added to a stirred dichloromethane (10 ml) solution of
Scheme 4.

206
M. Peruzzini et al. / Inorganica Chimica Acta 339 (2002) 202ꢂ208
/
the complex [(triphos)Re(CO)2(OTf)]BF4 (5) at room
temperature (r.t.). During this time, the color of the
resulting solution changed from pale yellow to orange.
After stirring was continued for 30 min, the solvent was
removed under reduced pressure and the solid pale
(br s, JHbHgꢁ
30H). 13C{1H} NMR (CD2Cl2, 21 8C, 50.32 MHz):
dꢁ199.6 (m, CO), 141.2 (dt, JCPtrans 39.7 Hz, JCPcis
2.8 Hz, Ca), 110.4 (dt, JCPtrans 5.2 Hz, JCPcis 1.8 Hz,
Cb), 69.2 (d, JCP 3.1 Hz, Cd), 40.7 (q, JCP 9.2 Hz,
CH3(triphos)), 39.7 (q, JCP 5.9 Hz, MeC(triphos)), 35.9
(td, Nꢁ CPequat?ꢀ CPequatƒꢁ14.0 Hz, JCPaxial 5.9 Hz,
CH2Pequat), 33.4 (dt, JCPaxial 21.4 Hz, JCPequat 2.8
Hz, CH2Paxial), 32.9 (s, Cg). 31P{1H} NMR (CD2Cl2,
22 8C, 81.01 MHz): AM2 spin system, dAꢁ 8.25,
dMꢁ 16.79, JAM 16.0 Hz.
/
2.3 Hz, Hb, 1H), 7.6ꢂ
/
7.1 (m, Haromatic
/
ꢁ
/
ꢁ
/
ꢁ
/
ꢁ
/
ꢁ
/
ꢁ
/
orange residue was washed with 2ꢄ/2 ml of ethanol and
ꢁ
/
2ꢄ3 ml of diethyl ether. Yield 85%. Anal. Calc. for
/
/
J
/J
/
ꢁ
/
C48H45F3O6P3ReS: C, 53.08; H, 4.18. Found: C, 53.21;
H, 4.25%. H, 13C{1H} and 31P{1H} NMR data were
ꢁ
/
ꢁ
/
1
identical with those of a specimen prepared as pre-
viously described [5].
/
ꢃ
/
/
ꢃ
/
ꢁ
/
3.3. Synthesis of [(triphos)Re(CO)2(ꢀ
/
3.5. Synthesis of [(triphos)Re(CO)2(Cꢀ
/
CCH2CH2CH2CH2O)]OTf (3-OTf)
CHCH2CH2CH2O)] (7)
Complex 3-OTf was synthesized by the method
described above for 2-OTf using 4-pentyn-l-ol instead
of 3-butyn-1-ol. Yield 88%. Anal. Calc. for
C49H47F3O6P3ReS: C, 53.50; H, 4.31. Found: C, 53.27;
This complex was prepared as described above for 6
using the 2-oxacyclohexylidene 3-OTf instead of 2-OTf.
Work-up as above gave 7 as white-off microcrystals in
87% yield after recrystallization from dichloromethaneꢂ
/
1
H, 4.48%. H, 13C{1H} and 31P{1H} NMR data were
ethanol. Anal. Calc. for C46H42O3P3Re: C, 59.93; H,
4.59. Found: C, 60.12; H, 4.70; 2.28%. IR: n(CO) 1939,
identical with those of a specimen prepared as pre-
viously described [5].
1879 (vs), n(Cꢀ
/
C) 1610 (m), n(COC) 1200 (w) cmꢃ1. 1H
The tetrafluoroborate salts 2-BF4 and 3-BF4 were
obtained in almost quantitative yield by reaction of the
corresponding triflates in dichloromethane with a slight
excess of sodium tetrafluoroborate dissolved in EtOH.
Crystals of 3-BF4 suited for an X-ray diffraction analysis
were grown by slow concentration from a diluted
NMR (CD2Cl2, 21 8C, 500.13 MHz, the labeling
scheme for the hydrogen and carbon resonances of
this complex is given in sketch V):
dichloromethaneꢂdiethyl ether solution (1:1 v/v).
/
dꢁ
J
J
/
1.36 (q, JHP
HdHgꢁ HdHoꢁ
HgHdꢁ6.7 Hz, Hg, 2H), 2.25 (d, JHPaxial
ꢁ2.3 Hz, CH3(triphos), 3H), 1.58 (psqu,
/
3.4. Synthesis of [(triphos)Re(CO)2(Cꢀ
/
/
J
/
5.6 Hz, Hd, 2H), 1.80 (br q, JHgHbꢁ
/
CHCH2CH2O)] (6)
/
ꢁ/7.9 Hz,
CH2Paxial, 2H), 2.40 (m, CH2Pequat, 4H), 3.50 (t,
HoHdꢁ5.0 Hz, Ho, 2H), 4.73 (t, JHbHgꢁ3.4 Hz, Hb,
1H), 7.4ꢂ
7.0 (m, Haromatic 30H). 13C{1H} NMR
(CD2Cl2, 23 8C, 75.43 MHz): dꢁ202.7 (m, CO),
141.4 (dt, JCPtrans 39.9 Hz, JCPcis 2.6 Hz, Ca), 113.1
(br d, JCPtrans 4.6 Hz Cb), 65.4 (d, JCP 3.0 Hz, Co),
40.6 (q, JCP 9.6 Hz, CH3(triphos)), 39.7 (q, JCP 3.5 Hz,
MeC(triphos)), 36.3 (td, Nꢁ CPequat?ꢀ CPequatƒꢁ14.2
Hz, JCPaxial 4.8 Hz, CH2Pequat), 34.8 (d, JCPaxial
Solid NaOMe (25 mg, 0.46 mmol) was added in small
portions to a stirred THF solution (25 ml) of 2-OTf
(0.20 g, 0,20 mmol) at r.t. After 20 min stirring, the
J
/
/
/
/
solvent was stripped out under vacuum and the whiteꢂ
grey residue was thoroughly washed with cold methanol
(2ꢄ3 ml) and diethyl ether (2ꢄ5 ml) before being dried
under nitrogen. Yield 88%. Crystallization from
dichloromethaneꢂdiethyl ether gave white needles of
/
ꢁ
/
ꢁ
/
ꢁ
/
ꢁ
/
/
/
ꢁ
/
ꢁ
/
/J
/J
/
/
ꢁ
/
ꢁ
/
analytically pure 6. Yield 83%. Anal. Calc. for
C47H44O3P3Re: C, 60.31; H, 4.74. Found: C, 60.07; H,
19.6 Hz, CH2Paxial), 24.3 and 24.0 (all s, Cg and Cd).
31P{1H} NMR (CD2Cl2, 22 8C, 81.01 MHz): AM2 spin
4.89%. IR: n(CO) 1933, 1871 (vs), n(Cꢀ
/
C) 1620 (m),
system, dAꢁ
/
ꢃ
/
7.90, dMꢁ
/
ꢃ
/
16.13, JAM
ꢁ14.9 Hz.
/
n(COC) 1190 (w) cmꢃ1 1H NMR (CD2Cl2, 21 8C,
200.13 MHz, the labeling scheme for the hydrogen and
carbon resonances of this complex is given in sketch IV):
.
3.6. In situ protonation of 6 (or 7) with CF3SO3H
One equivalent of triflic acid (2.5 ml, 2.9ꢄ
/
10ꢃ2
mmol) was syringed at r.t. into a 5-mm screw-cap
NMR tube containing a solution of 25 mg of 6 (2.7ꢄ
/
dꢁ
partially superimposed to the CH2P resonances, Hg,
2H), 2.34 (d, JHPaxial 9.8 Hz, CH2Paxial, 2H), 2.43 (m,
CH2Pequat, 4H), 3.77 (t, JHdHgꢁ9.2 Hz, Hd, 2H), 4.42
/
1.38 (q, JHP
ꢁ
/
2.7 Hz, CH3(triphos), 3H), 2.28 (m,
10ꢃ2 mmol) in 0.8 ml of degassed CD2Cl2. 31P{1H}
NMR monitoring of the solution immediately con-
firmed the complete formation of the 2-oxacyclopenty-
lidene complex 2-OTf. On replacing 6 with 7 in the
ꢁ
/
/

M. Peruzzini et al. / Inorganica Chimica Acta 339 (2002) 202ꢂ
/
208
207
above procedure, the 2-oxacyclohexylidene complex 3-
OTf was obtained in quantitative NMR yield.
Table 2
Crystal data and structure refinement for [(triphos)Re-
(CO)2{ꢀCCH2CH2CH2CH2O}]BF4 (3-BF4)
Empirical formula
Formula weight
Temperature (K)
C48H47BF4O3P3Re
1037.78
3.7. In situ protonation of 6 with CF3SO3D
293(2)
0.71069
˚
Wavelength (A)
One equiv. of deuterated triflic acid (2.3 ml, 2.6ꢄ
10ꢃ2 mmol) was added via syringe into a 5-mm screw-
cap NMR tube containing 25 mg of 6 (2.7ꢄ
10ꢃ2
mmol) in 0.8 ml of degassed CD2Cl2 at r.t. The selective
formation of CCH(D)CH2-
[(triphos)Re(CO)2{ꢀ
CH2O}]OTf (2-OTf-d1) was shown by the appearance
of a multiplet (1H) centered at 3.3 ppm in place of the
Hb triplet of 2-OTf). [5]
/
Crystal system
Space group
Unit cell dimensions
monoclinic
P21/n (no. 14)
/
˚
a (A)
10.835(3)
17.859(3)
22.875(4)
90.000(5)
96.41(2)
90.000(5)
4398.7(16)
4
˚
b (A)
˚
c (A)
/
a (8)
b (8)
g (8)
3
˚
Volume (A )
Z
Density (calculated) (mg mꢃ3
)
1.567
2.930
Absorption coefficient (mmꢃ1
F(000)
Crystal size (mm)
)
3.8. X-ray diffraction study of [(triphos)Re(CO)2(ꢀ
/
2080
0.63ꢄ0.20ꢄ0.20
CCH2CH2CH2CH2O)]BF4 (3-BF4)
Theta range for data collection 2.71ꢂ
/22.48
(8)
Index ranges
Pale orange crystals of 3-BF4 were grown in air from a
ꢃ115h 511, 05k 519,
05l 524
5896
dilute dichloromethaneꢂ/diethyl ether solution. A paral-
lelepiped crystal with dimension 0.63ꢄ
/
0.20ꢄ0.20 mm
/
Reflections collected
Independent reflections
5731 (Rintꢁ0.0187)
was used for the data collection. A summary of crystal
and intensity data is presented in Table 2. Experimental
Completeness to thetaꢁ22.488 99.8%
Max. and min. transmission
Refinement method
0.5918 and 0.2617
data were acquired at r.t. (20 8C) on an Enrafꢂ
CAD4 diffractometer. A set of 25 carefully cantered
reflections in the range 6.58Bu B9.58 was used for
/
Nonius
Full-matrix least-squares on F2
5731/21/239
1.036
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I ꢀ2s(I)]
R indices (all data)
/
/
R1ꢁ0.0432, wR2ꢁ0.1065
R1ꢁ0.0698, wR2ꢁ0.1215
1.358 and ꢃ0.909
determining the lattice constants. As a general proce-
dure, the intensity of three standard reflections was
measured periodically every 200 reflections for orienta-
tion and intensity control. This procedure did not reveal
an appreciable decay of intensities. The intensities were
corrected for Lp effects. Atomic scattering factors were
those tabulated by Cromer and Waber [18] with
anomalous dispersion corrections taken from reference
[19]. An empirical absorptions correction was applied
Largest diff. peak and hole
ꢃ3
˚
(e A
)
4. Supplementary material
Crystallographic data (excluding structure factors) for
the structure of 3-BF4 have been deposited with the
Cambridge Crystallographic Data Centre, CCDC No.
173239. Copies of these data can be obtained free of
charge from the Director, CCDC, 12 Union Road,
via C scan with correction factors in the range 0.898ꢂ
/
0.998. The computational work was carried out by using
the program SHELX97 [20], while the structure was
solved by direct methods using the SIR92 program [21].
Refinement was done by full-matrix least-squares
calculations, initially with isotropic thermal parameters
then with anisotropic thermal parameters for Re, P and
C atoms of the triphos skeleton. The phenyl rings were
treated as rigid bodies with D6h symmetry, and the
hydrogen atoms were allowed to ride on the attached
carbon atoms. Crystallographic disorder was detected in
the region of the 2-oxa-cyclohexylidene ligand resulting
in a double image of the O(3), C(9), C(10), C(11) and
C(12) atoms. The two sets of atoms were assigned a
Cambridge CB2 1EZ, UK (fax: ꢀ44-1223-336-033; e-
/
mail: deposit@chemcrys.cam.ac.uk).
Acknowledgements
D. Akbayeva thanks ‘BASF AG’ (Ludwigshafen,
Germany) for a post-doctoral grant at ISSECC CNR,
Florence, Italy. Thanks are expressed to Mr. Dante
Masi (ISSECC CNR) for collecting X-ray data, to
INTAS (project 00-00018) and COST D17 Action
WG/D17-003/00 for supporting this research.
population factor of 0.67 and 0.33, respectively. The Bꢁ
/
F distances and the FÁ Á ÁF separations in the tetrafluor-
oborate anion were restrained to be equal with the S.D.
of 0.02.

208
M. Peruzzini et al. / Inorganica Chimica Acta 339 (2002) 202ꢂ208
/
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