Reactivity of cationic dinitrosyl bisphosphine rhenium complexes toward acetylene: base-controlled product formation

Article abstract of DOI:10.1021/om9003412

Reactions of the dinitrosyl bisphosphine rhenium cations [Re(NO) ₂(PR₃)₂][BAr^F₄] (R = Cy la; R = iPr 1b; [BAr^F₄]~ = tetrakis[(3,5- bis(trifluoromethyl)phenyl)borate]) with acetyl

Full text of DOI:10.1021/om9003412

Organometallics 2009, 28, 5333–5340 5333
DOI: 10.1021/om9003412
Reactivity of Cationic Dinitrosyl Bisphosphine Rhenium Complexes
toward Acetylene: Base-Controlled Product Formation
C. M. Frech, A. Llamazares, O. Blacque, H. W. Schmalle, and H. Berke*
Department of Inorganic Chemistry, University of Zurich, 8057 Zurich, Switzerland
Received April 30, 2009
Reactions of the dinitrosyl bisphosphine rhenium cations [Re(NO)2(PR3)2][BArF4] (R = Cy 1a;
R = iPr 1b; [BArF4]- = tetrakis[(3,5-bis(trifluoromethyl)phenyl)borate]) with acetylene yielded the
alkynyl (o-vinyl)hydroxylamido nitrosyl bisphosphine complexes [Re(CHdC(H)ONH)(CtCH)-
(NO)(PR3)2][BArF4] (3a and 3b) in the absence of base, while in the presence of 2,6-di(tert-
butyl)pyridine formation of the neutral alkynyl complexes [Re(CtCH)(NO)2(PR3)2] (4a and 4b)
was observed. A plausible mechanism is presented and supported by various NMR techniques, IR
spectroscopy, and DFT calculations. Treatment of 4a and 4b with [H(OEt2)2][BArF4] gave the
corresponding vinylidene complexes [Re(CdCH2)(NO)2(PR3)2][BArF4] (5a and 5b) in high yields,
which only slowly convert into the alkynyl(o-vinyl)hydroxylamido nitrosyl bisphosphine complexes
3a and 3b when treated with a large excess of acetylene. Thiophenol or benzeneselenol underwent
1,2-additions onto the vinylidene ligands of 5a and 5b to yield the cationic Fischer-type carbene
complexes [Re(C(XPh)CH3)(NO)2(PR3)2][BArF4] (X = S 6a,b; X = Se 7a,b) quantitatively. X-ray
diffraction studies were carried out on 4b, 5b, and 7a.
Introduction
rhenium(-I) complexes [Re(NO)2(PR3)2][BArF ] (R = Cy 1a;
4
R=iPr 1b;[BArF ]-=tetrakis[(3,5-bis(trifluoromethyl)phenyl)-
4
borate]) and dinuclear rhenium carbonyl compounds.6-8
Whereas 1a and 1b possess catalytic activity in ROMP processes,
The transition metal catalyzed olefin metathesis is nowa-
days one of the most widely used organic transformations.1-4
Despite the fact that heterogeneous rhenium olefin metathesis
catalysts are superior over their molybdenum- or tungsten-
based analogues, defined soluble rhenium metathesis systems
have rarely been found to show high catalytic activity.5 The
only catalyst precursors with rhenium in low oxidation states
are the recently reported cationic dinitrosyl bisphosphine
their benzylidene derivatives [Re(dCHPh)(NO)2(PR3)2][BArF ]
4
(R = Cy and iPr) were found to be inactive in olefin metathesis
reactions, presumably due to their insufficient initiation proper-
ties of the catalyses. Since low-valent dinitrosyl bisphosphine
complexes of molybdenum and tungsten were reported to
efficiently promote olefin metathesis reactions,9,10 it was antici-
pated that their rhenium analogues with the general formula
[Re(alkylidene)(NO)2(PR3)2]þ might principally be catalytically
active as well. On the basis that the electrophilic character of
dinitrosyl rhenium complexes’ alkylidene ligands with reduced
π-accepting properties seemed to be also appropriate, we probed
Fischer-carbene rhenium complexes.8,11,12
*Corresponding author E-mail: hberke@aci.uzh.ch.
(1) Ivin, K. J.; Mol, J. C. In Olefin Metathesis and Metathesis
Polymerization; Ivin, K. J., Mol, J. C., Eds.; Academic Press: San Diego,
1997.
(2) Zaragoza Dorwald, F. In Metal Carbenes in Organic Synthesis;
Wiley-VCH: Weinheim, 1999.
€
€
(3) Furstner, A. Angew. Chem. 2000, 112, 3140; Angew. Chem.
Synthetic access to Fischer-type rhenium carbene com-
plexes was based on acetylene or acetylide complexes with
Int. Ed. 2000, 39, 3012.
(4) Trnka, T. M.; Grubbs, R. H. Acc. Chem. Res. 2000, 34, 18.
(5) Chen, X.; Zhang, X.; Chen, P. Angew. Chem., Int. Ed. 2003, 42,
3798.
(6) (a) Herrmann, W. A. J. Organomet. Chem. 1995, 500, 149. (b)
Romao, C. C.; K€uhn, F. E.; Herrmann, W. A. Chem. Rev. 1997, 97, 3197. (c)
Schrock, R. R.; Depue, R. T.; Feldman, J.; Schaverien, C. J.; Dewan, J. C.;
Liu, A. H. J. Am. Chem. Soc. 1988, 110, 1423. (d) Schofield, M. H.;
Schrock, R. R.; Park, L. Y. Organometallics 1991, 10, 1844. (e) Weinstock,
A.; Schrock, R. R.; Davis, W. M. J. Am. Chem. Soc. 1991, 113, 135. (f)
Toreki, R.; Schrock, R. R. J. Am. Chem. Soc. 1990, 112, 2448. (g) Toreki, R.;
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G. A.; Schrock, R. R.; Davis, W. M. J. Am. Chem. Soc. 1993, 115, 127. (i)
Toreki, R.; Schrock, R. R.; Davis, W. M. J. Organomet. Chem. 1996, 520,
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Chem. Soc. 1993, 115, 2980. (k) LaPointe, A. M.; Schrock, R. R. Organo-
metallics 1995, 14, 1875.
(8) Frech, C. M.; Blacque, O.; Schmalle, H. W.; Berke, H.; Adlhart,
C.; Chen, P. Chem.;Eur. J. 2006, 12, 3325.
(9) Zuech, E. A.; Hughes, W. B.; Kubicek, D. H.; Kittelman, E. T.
J. Am. Chem. Soc. 1970, 92, 528.
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Taube, R.; Seyferth, K. Z. Chem. 1977, 13, 300. (c) Leconte, M.; Basset,
J.-M. J. Am. Chem. Soc. 1979, 101, 7296. (d) Seyferth, K.; Rosenthal, K.;
K€uhn, G.; Taube, R. Z. Anorg. Allg. Chem. 1984, 513, 57. (e) Seyferth, K.;
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(11) Frech, C. M.; Blacque, O.; Schmalle, H. W.; Berke, H. Chem.;
Eur. J. 2006, 12, 5198.
(12) Jacobsen, H.; Heinze, K.; Llamazares, A.; Schmalle, H. W.;
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r
2009 American Chemical Society
Published on Web 09/03/2009
pubs.acs.org/Organometallics

5334 Organometallics, Vol. 28, No. 18, 2009
Frech et al.
Scheme 1
subsequent conversion into their vinylidene derivatives to
enable 1,2-additions with protic nucleophiles, affording the
desired alkylidene derivatives.
In fact, proton addition to the NNO atom or the rhenium
center was not observed. This latter observation contrasts
the occurrence of 2a and 2b when starting from 1a and 1b and
acetylene and therefore excludes that acetylide complexes of
type 4 are involved in the reaction course to 3a or 3b
(Scheme 1). 3a and 3b could be isolated as black solids in
moderate yields (∼50%). Slightly improved yields were
obtained at prolonged reaction times; thus a ∼60% yield
of 3a could be reached after three days and is accompanied
by the formation of the cationic vinylidene complexes 5a
and 5b, as indicated by NMR spectroscopy. However, the
elemental analyses and the spectroscopic data of 3a and 3b
were in agreement with the formation of the alkynyl-
(o-vinyl)hydroxylamido nitrosyl bisphosphine structures.
For example, the 31P{1H} NMR spectra of 3a and 3b revealed
singlets at δ = 36.5 ppm and at δ = 43.0 ppm (THF-d8),
Results and Discussion
Synthesis of Alkynyl(o-vinyl)hydroxylamido Nitrosyl Bis-
phosphine Rhenium Complexes 3a and 3b. When benzene
solutions of the cationic dinitrosyl bisphosphine rhenium
complexes [Re(NO)2(PR3)2][BArF4] (R = Cy 1a; R = iPr 1b)
were treated with acetylene at room temperature, the
alkynyl(o-vinyl)hydroxylamido nitrosyl bisphosphine rhe-
nium cations [Re(CtCH)(CHdC(H)ONH)(NO)(PR3)2]-
[BArF4] (3a and 3b) precipitated from solution within 1 h,
similar to the reported transformations of 1a and 1b with
phenylacetylene.13 A mechanistic path is expected to be
initiated by coordination of acetylene on 1a and 1b. Indeed,
when solutions of 1a and 1b in chlorobenzene-d5 were treated
with an excess of acetylene at -35 ꢀC, an immediate color
change occurred from dark red to yellow, indicating the
initial formation of the acetylene adducts of type 2
(Scheme 1). These acetylene adducts (2a and 2b) were
characterized by 1H and 31P{1H} NMR spectroscopy in
solution. Their 31P{1H} NMR spectra showed singlets at
δ = 16.2 and 24.1 ppm, while the 1H NMR spectra in THF-
d8 exhibited broad triplets at δ ∼7.8 ppm (JPH = 3.7 Hz),
which were assigned to the hydrogen atoms of the acetylene
ligands. Subsequent formation of the acetylide hydride
species A could lead to the prototropic nitroxyl acetylide
intermediates of type B. These 16e- species B then coordi-
nate another acetylene molecule to undergo a 1,3-dipolar
addition of the ReN(H)O moiety via C and yield 3a and 3b.14
Alternatively, 2a and 2b might be deprotonated to form the
neutral acetylide complexes 4a and 4b. Treatment of methy-
lene chloride solutions of 4a and 4b with equimolar amounts
of [H(Et2O)2][BArF4] yielded the cationic vinylidene com-
plexes 5a and 5b (see below). Protonation of the acetylide
unit may be kinetically or thermodynamically determined.
1
respectively. In the H NMR spectra singlets were found at
δ ≈ 8.90 ppm, which were attributed to the NH protons. The
vinylic hydrogen atoms of the (o-vinyl)hydroxylamido moi-
eties gave rise to signals at δ = 5.76 and 5.02 ppm and at δ =
5.69 and 5.26 ppm, respectively, whereas the acetylide protons
appeared at δ = 4.34 and 4.41 ppm. Due to the low solubility
of 3a and 3b in all common organic solvents and in water,
13C{1H} NMR spectra (or even 2D COSY NMR spectra)
could not be obtained. The IR spectra exhibited characteristic
absorptions at approximately 1720 cm-1 (νNO), 1600 cm-1
(νHNO), and 2090 cm-1 (νCtC) of both derivatives, consistent
with the proposed structure of 3a and 3b.
Both reactions, that to the cationic dinitrosyl bispho-
sphine vinylidene complexes 5a and 5b and that to 3a and
3b, are thus assumed to pass through the acetylide hydride
complexes of type A and are thought to be reversible at room
temperature, however, with different rates. Reversibility of
the reaction of the vinylidene complexes 5a and 5b with A is
supported by the observation that when methylene chloride
solutions were treated with an excess (∼50 equiv) of acetylene
gas, very slow formation of the alkynyl (o-vinyl)hydroxyl-
amido nitrosyl bisphosphine complexes 3a and 3b was obser-
ved (10% conversion within three days).
(13) Frech, C. M.; Llamazares, A.; Alfonso, M.; Schmalle, H. W.;
Berke, H. Russ. Chem. Bull., Int. Ed. 2004, 53, 1.
DFT Calculations. Since the course of the reaction could
not fully be unravelled spectroscopically withall its alternative
pathways and intermediates, DFT calculations were sought
using trimethylphosphine model complexes replacing PiPr3
and PCy3 of the experimental systems. A plausible reaction
path could be established relating 1-Me and acetylene with
3-Me in a strongly exothermic process (-70.1 kcal/mol) in the
(14) (a) Werner, H.; Wolf, J.; Alonso, F. J.; Garcia; Ziegler, M. L.;
Serhadli, O. J. Organomet. Chem. 1987, 336, 397. (b) Hoehn, A.; Werner,
H. J. Organomet. Chem. 1990, 382, 255. (c) Werner, H.; Hampp, A.; Peters,
K.; Peters, E. M.; Walz, L.; Von Schnering, H.-G. Z. Naturforsch., B: Chem.
Sci. 1990, 45, 1548. (d) Schaefer, M.; Wolf, J.; Werner, H. J. Organomet.
Chem. 1995, 485, 85. (e) Schaefer, M.; Wolf, J.; Werner, H. Organometallics
2004, 23, 5713.

Article
Organometallics, Vol. 28, No. 18, 2009 5335
Figure 1. Energy diagram for calculated intermediates and transition states of the reaction of the cation 1-Me with acetylene. Relative
total energies are in kcal/mol with respect to those of 1-Me and C2H2.
reaction with acetylene. The computed minimum energy
pathways are presented in Figure 1.
complexes A-Me on a least-motion pathway. The calculated
total reaction barrier for this reverse reaction of 30.7 kcal/
mol (5 -Me f A-Me) is then split up in two parts, and the last
big jump in energy is reduced by 4.8 kcal/mol. Nevertheless,
the calculated residual reaction barrier of 25.9 kcal/mol is
still relatively high. If it matches reality, we have to assume a
very slow back-reaction, indeed in line with the experi-
ments.16 Addition of the second acetylene molecule to the
16e- metal center of B-Me to form C-Me is calculated to be
exothermic by -15.0 kcal/mol. The subsequent rearrangement
of C-Me leading to 3-Me can be interpreted in terms of a 1,3-
dipolar addition with primary nucleophilic attack of OHNO onto
the acetylene ligand (see Figure 2). The process was calculated
to be energetically highly favorable by 43.9 kcal/mol with a
reaction barrier (TS3) of only 5.6 kcal/mol.
Summarizing the calculations, one could state that the
crucial reaction barrier of the whole process from complexes
of type 1 to those of type 3 is set by the transformation of the
acetylene complexes 2 to hydride acetylide species A, and if
the vinylidene species of type 5 are starting materials, they
can be converted only by a still slower reaction.
Synthesis of Alkynyl Complexes 4a and 4b. The formation
of 3a and 3b was suppressed when acetylene was added to
benzene or chlorobenzene solutions of 1a and 1b at room
temperature in the presence of a noncoordinating base such
as 2,6-di(tert-butyl)pyridine. Apparently deprotonation of
the acidic proton of the acetylene ligand of intermediates
of type A promotes fast and clean conversions into the stable
σ-alkynyl complexes [Re(CtCH)(NO)2(PR3)2] 4a and 4b,
which were isolated in good yields (∼80%) as orange pow-
ders (Scheme 2). The type of added base, however, turned out
to be crucial. When KOtBu was used, significantly lower
yields (∼50%) of 4a and 4b and in addition precipitation of
3a and 3b were observed. This difference in the reaction
Coordination of acetylene to the rhenium center of 1-Me
to form the acetylene complex 2-Me is accompanied by a
25.1 kcal/mol stabilization. The η2-coordinated acetylene
orients itself perpendicular to the P-Re-P axis as expected
for π acceptors in d8 trigonal-bipyramidal structures.15
Complex 3-Me (in the presence of another acetylene
molecule) is tremendously energetically greatly favored over
2-Me by 45.0 kcal/mol, so that a gradual energetic descent to
the product seems possible. The first step includes the for-
mation of the hydride acetylide intermediate A-Me, which is
endothermic by 9.6 kcal/mol with respect to 2-Me. The
optimized transition state TS1, which connects 2-Me and
A-Me, constitutes a relatively high reaction barrier of 25.1
kcal/mol. A dead-end track leads from A-Me to the vinyli-
dene complex 5-Me. The direct rearrangement of 2-Me to 5-
Me via a 1,2-H shift could not be established by DFT.
A reasonable pathway including a transition state could
not be found on the given energy hypersurface. Starting from
A-Me, migration of the HRe atom was found to lead either to
the nitroxyl intermediate B-Me or alternatively to the catio-
nic vinylidene complex 5-Me, since the calculated transition
q
states are of very close in energy (ΔΔE0 = 0.4 kcal/mol).
This result approximately matches with the experimentally
observed product distribution of the vinylidene complexes 5
and the 3-rhena-2,3-dihydroisoxazoles 3. It is noteworthy
that the vinylidene unit of 5-Me possesses somewhat hin-
dered rotation with the prominent rotamer 5 -Me, where the
vinylidene hydrogen atoms are parallel to the P-Re-P axis.
The other rotamer 5^-Me, with the vinylidene hydrogen
atoms perpendicular to the P-Re-P axis, lies 4.8 kcal/mol
higher in energy. The perpendicular rotamers seem to be very
plausible intermediates reverting 5ab to the hydride acetylide
(16) The calculated reaction barrier difference of 5^-Me f A-Me and
A-Me f B-Me is 0.8 kcal/mol and compares well with the experimental
observations.
(15) Albright, T. A.; Burdett, J. K.; Whangbo, M.-H. In Orbital
Interactions in Chemistry; John Wiley & Sons, Inc.: New York, 1984.

5336 Organometallics, Vol. 28, No. 18, 2009
Frech et al.
Figure 2. Views of optimized structures of various intermediates and a transition state. Values in kcal/mol represent the relative
energies with respect to 1-Me and two acetylenes.
Scheme 2
behavior was explained on the basis of a kinetically too slow
base attack of the heterogeneous KOtBu reagent. The
31P{1H} NMR spectra of both alkynyl complexes 4a and
4b exhibited singlet resonances at δ = 20.6 and 26.4 ppm in
benzene solutions. The 1H NMR spectra showed phosphine
signals in addition to a broad poorly resolved triplet at δ =
4.14 ppm (JPH = 3.9 Hz) for 4a and a well-defined triplet at
δ = 4.04 ppm (JPH = 4.2 Hz) for 4b, which were assigned
to the hydrogen atoms of the alkynyl units. The 13C{1H}
NMR spectra displayed triplets at δ = 111.9 and 111.7 ppm
(JPC = 19 and JPC = 19 Hz) and at δ = 127.8 and 126.3 ppm
(JPC = 2 Hz for both) for the acetylenic carbon atoms.
The latter resonances of the Cβ atoms showed correla-
tion with the signals of the alkynyl protons at δ = 4.14 ppm
(4a) and at δ = 4.04 ppm (4b) in the 2D spectra. The IR
spectra of 4a and 4b exhibited two characteristic ν(NO)
absorptions at 1581 and 1621 cm-1 and at 1576 and 1618
cm-1, respectively.
complex [(triphos)(CO)2Re{CtCC(Ph)2(pyrazolyl)}], where
Re-C and C-C bond distances of 2.118(5) and 1.203(8) A
˚
were measured.17 The hydrogen atom H1 was located in the
difference Fourier map and refined isotropically. An ORTEP
plot of the crystal structure of 4b is presented in Figure 3. 4a is
a rare example of a rhenium alkynyl derivative analyzed by
X-ray diffraction methods. The few crystallographically stu-
died rhenium alkynyl complexes have the rhenium center in the
oxidation state of þI, and most of them are cyclopentadienyl
or carbonyl derivatives; their Re-CR and CR-Cβ bond dis-
tances have been found to vary within a very large range.18,19
Synthesis of Vinylidene Complexes 5a and 5b. Asmentioned
above, equimolar amounts of the acid [H(OEt2)2][BArF4] can
(17) (a) Mantovani, N.; Bergamini, P.; Marchi, A.; Marvelli, L.;
Rossi, R.; Bertolasi, V.; Ferretti, V.; De los Rios, I.; Peruzzini, M.
Organometallics 2006, 25, 416. (b) Yam, V.; Lau, C.; Cheung, K.-K.
Organometallics 1995, 14, 2749.
(18) See for instance: (a) Dembinski, R.; Lis, T.; Szafert, S.; Mayne,
C. L.; Bartik, T.; Gladysz, J. A. J. Organomet. Chem. 1999, 578, 229. (b)
Falloon, S. B.; Weng, W.; Arif, A. M.; Gladysz, J. A. Organometallics 1997,
16, 2008. (c) Senn, D. R; Wong, A.; Patton, A. T.; Marsi, M.; Strouse, C. E.;
Gladysz, J. A. J. Am. Chem. Soc. 1988, 110, 6096. (d) Paul, F.; Meyer, W. E;
Toupet, L.; Jiao, H.; Gladysz, J. A; Lapinte, C. J. Am. Chem. Soc. 2000, 122,
9405. (e) Weng, W.; Ramsden, J. A; Arif, A. M.; Gladysz, J. A. J. Am. Chem.
Soc. 1993, 115, 3824.
(19) See for instance: (a) Lam, S. C.-F.; Yam, V. W.-W.; Wong, K.
M.-C.; Cheng, E. C.-C.; Zhu, N. Organometallics 2005, 24, 4298. (b)
Yam, V.W.-W.; Lau, V. C.-Y.; Cheung, K.-K. Organometallics 1996, 15,
1740. (c) Chong, S. H.-F.; Lam, S. C.-F.; Yam, V. W.-W.; Zhu, N.; Cheung,
K.-K. Organometallics 2004, 23, 4924. (d) Ferrer, M.; Rodriguez, L.;
Rossell, O.; Lima, J. C.; Gomez-Sal, P.; Martin, A. Organometallics 2004,
23, 5096. (e) Yam, V. W.-W.; Chong, S. H.-F.; Ko, C.-C.; Cheung, K.-K.
Organometallics 2000, 19, 5092. (f) Yam, V. W.-W.; Chong, S. H.-F.;
Cheung, K.-K. Chem. Commun. 1998, 2121. (g) Wong, K. M.-C.; Lam, S.
C.-F.; Ko, C.-C.; Zhu, N.; Yam, V. W.-W.; Roue, S.; Lapinte, C.; Fathallah, S.;
Costuas, K.; Kahlal, S.; Halet, J.-F. Inorg. Chem. 2003, 42, 7086.
In order to further support the spectroscopically assigned
structures of these alkynyl complexes, an exemplary X-ray
diffraction study was carried out on single crystals of 4b
(Figure 5). Well-diffracting crystals were grown at -30 ꢀC
by slow diffusion of n-pentane into a concentrated toluene
solution of 4b. The solid state structure revealed the rhenium
center in
a
pseudo-trigonal-bipyramidal environment
(N1-Re1-N2 = 120.83(15)ꢀ, C1-Re1-N1 = 119.28(16)ꢀ,
C1-Re1-N2 = 119.86(17)ꢀ) with the two phosphine ligands
in axial positions. The P1-Re1-P2 angle is 164.07(3)ꢀ and
both ligands hinge toward the acetylide ligand, as it was also
observed in related systems.12 The Re1-C1 and C1-C2 bond
˚
distances of 4b are 2.127(4) and 1.182(6) A and compare well
with the bond distances of the recently reported alkynyl

Article
Organometallics, Vol. 28, No. 18, 2009 5337
Figure 4. Molecular structure of 5b with 30% probability dis-
]
-
placement ellipsoids. The [BArF
except H1 and H2, have been omitted for clarity. Selected bond
anion and all H atoms,
Figure 3. Molecular structure of 4b with 20% probability dis-
placement ellipsoids. All H atoms, except for H1, have been
˚
omitted for clarity. Selected bond distances (A) and angles (deg):
4
˚
distances (A) and angles (deg): Re1-N1 = 1.830(5), Re1-
Re1-N1 = 1.788(3), Re-N2 = 1.790(3), Re1-C1 = 2.127(4),
C1-C2 = 1.182(6), C2-H1 = 1.00(6). N1-O1 = 1.208(4),
N2-O2 = 1.199(4), N1-Re1-N2 = 120.83(15), P1-Re1-
P2 = 164.07(3), N1-Re1-C1 = 119.28(16), N2-Re1-C1 =
119.86(17), Re1-C1-C2 = 174.5(5), C1-C1-H1 = 175(4),
Re1-N1-O1 = 171.0(3), Re1-N2-O2 = 172.5(3).
N2 = 1.827(5), Re1-C1 = 1.902(6), C1-C2 = 1.309(9),
N1-O1 = 1.185(6), N2-O2 = 1.178(7), N1-Re1-N2 =
147.2(2), N1-Re1-C1 = 106.5(3), N2-Re1-C1 = 106.3(2),
P1-Re1-P2 = 170.49(5).
positions. The Re1-C1 and C1-C2 bond distances are
1.902(6) and 1.309(9) A. Crystallographically characterized
˚
convert in methylene chloride the alkynyl complexes 4a and 4b
into the olive green vinylidene complexes [Re(CCH2)-
vinylidene complexes with rhenium centers are very rare.
They normally display Re-C and CdC bond distances in the
(NO)2(PR3)2][BArF ] 5a and 5b with protonation at the Cβ
21
˚
4
range 1.839-2.046 and 1.289-1.387 A, respectively. The
position. The 31P{1H} NMR spectra of 5a and 5b exhibit
singlets at δ = 24.8 ppm and at δ = 31.9 ppm, respectively,
and the 1H NMR spectra displayed all resonances attributable
to the phosphine ligands. The vinylidene protons appear as
triplets. Atδ=5.82 ppm (JPH = 2.3 Hz) one finds a unresolved
triplet for 5a and a well-defined triplet centered at δ = 5.57
ppm (JPH = 2.8 Hz) for 5b. The 13C{1H} NMR spectrum
exhibitsforthevinylidene unit of5aa broad signal at δ=322.5
and a singlet at δ = 122.0 ppm and for 5b a triplet at δ = 320.9
(JPC = 15.4 Hz) and a singlet at δ = 121.3 ppm. The IR
spectra display two characteristic ν(NO) absorptions at 1751
and 1652 cm-1 and one ν(CdC) absorption at 1612 cm-1 for
5a and at 1753, 1650, and 1609 cm-1, respectively, for 5b. Due
to the very different electronic properties of the vinylidene and
the alkynyl residues (π acceptor vs predominantly π donor
property) and the different charges of the complexes, the
ν(NO) absorptions are shifted dramatically to higher wave
numbers in comparison with those of 4a and 4b, for which
absorptions at 1621 and 1581 cm-1 (4a) and at 1618 and
1576 cm-1 (4b) were found. ON-Re-NO angles of approxi-
mately 140ꢀ were calculated from the ν(NO) band intensities
of 5a and 5b.20 Crystals of 5b suitable for X-ray diffraction
were grown by slow evaporation of a concentrated methylene
chloride solution. The determined molecular structure of 5b is
shown in Figure 4.
N1-Re1-N2 angle of 5b is 147.2(2)ꢀ and is significantly
larger with respect to the one found in complex 4b
(N1-Re1-N2 = 120.83(15)ꢀ). As suggested by the DFT
calculations on 5-Me, the orientation of the vinylidene CH2
plane is perpendicular to the trigonal plane of the trigonal
bipyramid, which reflects the tendency to optimize the over-
lap with the “better” in-plane π donor orbital of d8-C2v-
tetracoordinate metal fragments.
Synthesis of Fischer-Carbene Complexes [Re{C(XPh)-
CH3}(NO)2(PR3)2][BArF4] (X = S 6a,b; X = Se 7a,b). When
methylene chloride solutions of the vinylidene complexes 5a
and 5b were treated with an excess (10 equiv) or an equimolar
amount of thiophenol or benzoselenol, almost quantitative
formation of Fischer-type carbene complexes [Re{C(XPh)-
CH3}(NO)2(PR3)2][BArF4] (X = S 6a,b; X = Se 7a,b) was
observed. The reactions were over in a few seconds, accom-
panied by an immediate color change from olive green to
dark violet. The 31P{1H} NMR spectra revealed unique
singlets for all these compounds. The 1H NMR spectra
of these complexes showed not only signals for the phos-
phine ligands and the aryl residues but also resonances at
δ ≈ 3.4 ppm, which were assigned to the methyl groups of the
(21) (a) Kolobova, N. E.; Antonova, A. B.; Khitrova, O. M.; Antipin,
M. Y.; Struchkov, Y. T. J. Organomet. Chem. 1977, 137, 69. (b)
Pombeiro, A. J. L.; Jeffrey, J. C.; Pickett, C. J.; Richards, R. L. J. Organomet.
Chem. 1984, 277, C7. (c) Pombeiro, A. J. L.; Almeida, S. S. P. R.; Silva, M. F.
C. G.; Jeffrey, J. C.; Richards, R. L. J. Chem. Soc., Dalton Trans. 1989,
2381. (d) Bianchini, C.; Marchi, A.; Marvelli, L.; Peruzzini, M.; Romerosa,
A.; Rossi, R. Organometallics 1996, 15, 3804. (e) Valyaev, D. A.; Semeikin,
O. V.; Peterleitner, M. G.; Borisov, Y. A.; Khrustalev, V. N.; Mazhuga, A. M.;
Kremer, E. V.; Ustynyuk, N. A. J. Organomet. Chem. 2004, 689, 3837.
The rhenium center possesses approximate trigonal-bipyr-
amidal coordination with the phosphine ligands in axial
(20) (a) Beck, W.; Melnikoff, A.; Stahl, R. Chem. Ber. 1966, 99, 3721.
(b) Poletti, A.; Foffani, A.; Cataliotti, R. Spectrochim. Acta 1970, 26A,
1063.

5338 Organometallics, Vol. 28, No. 18, 2009
Frech et al.
carbene moieties. In the 13C{1H} NMR spectra resonances
were found with approximate chemical shifts of δ ≈ 305 ppm,
which are characteristic for the Ccarbene atoms. In the case of
the triisopropyl derivatives 6b and 7bthesesignals appearedas
well-defined triplets (JPC = 3.5 Hz), but as broad resonances
with unresolved couplings in the case of the tricyclohexyl
species 6a and 7a.
It was expected that the carbene ligands of 6a,b and 7a,b
would have significantly smaller ON-Re-NO angles than
those reported for their benzylidene derivatives [Re(dCHPh)-
(NO)2(PR3)2][BArF4].8 As a consequence, larger P-Re-P
angles and elongated Re-C bond distances were predicted.12
Indeed, the calculations of the angles from the ν(NO) IR
intensities of 6a and 6b and those of 7a and 7b resulted in
angles of approximately 140ꢀ,20 which compare well with the
ones determined for the vinylidene complexes 5a and 5b. An
exemplary X-ray diffraction study on 7a confirmed this
(Figure 5). Single crystals of 7a were grown by slow evapora-
tion of concentrated diisopropylether solutions at -30 ꢀC.
In the solid state 7a revealed a pseudo-trigonal-bipyramidal
coordination at the rhenium center (Figure 5). In accord with
theIR-derived data the N1-Re1-N2 angle is 146.69(14)ꢀ and
compares well to the respective one of 5b (N1-Re1-N2 =
147.2(2)ꢀ). In contrast to this, the P-Re-P angles differ
significantly (P1-Re1-P2 =163.63(4)ꢀ (7a) vs P1-Re1-
P2 = 170.49(5)ꢀ (5b)). The Re-C1 bond distance of 7a is
Figure 5. Molecular structure of 7a with 20% probability dis-
]
-
placement ellipsoids. The [BArF
atoms, with the exception of those from the methyl group, have
counteranion and all H
4
˚
been omitted for clarity. Selected bond distances (A) and angles
(deg): Re1-N1 = 1.814(5), Re1-N2 = 1.842(5), Re1-C1 =
1.994(5), C1-C2 = 1.535(6), C1-Se1 = 1.875(6), N1-Re1-
N2 = 146.73(19), N1-Re1-C1 = 99.5(2), N2-Re1-C1 =
113.8(2), P1-Re1-P2 = 163.63(4).
˚
1.994(5) A. Due to the reduced π-accepting properties of the
acetylene in the absence of a base yielded the alkynyl-
(o-vinyl)hydroxylamido nitrosyl bisphosphine complexes
[Re(CtCH){CHdC(H)ONH}(NO)(PR3)2][BArF4] (3a and
3b), while the neutral alkynyl complexes of type 4 were
formed in the presence of a base. A plausible reaction
mechanism for the conversion of the complexes of type 1
into those of type 3 was elaborated on the basis of experi-
mental observations and DFT calculations. Primary for-
mation of acetylene complexes allows access of hydride
acetylide compounds with H migration. These complexes
in turn undergo further H migration to form nitroxyl
compounds, which take up another acetylene molecule.
1,3-Dipolar addition of the acetylene to the nitroxyl rhe-
nium moiety furnishes type 3 complexes. Protonation of the
alkynyl complexes exclusively yielded the cationic vinyli-
dene species 5a and 5b, which undergo 1,2-additions with
protic nucleophiles to yield the Fischer-carbene complexes
6a,b and 7a,b. It was found that rhenium dinitrosyl bispho-
sphine Fischer-carbene complexes are not suitable as cata-
lysts for olefin metathesis-type reactions presumably due
to reduced electrophilicity of the carbene.12 On the basis of
the observations made it is assumed that bisphosphine
dinitrosyl alkylidene complexes of rhenium are generally
not suitable systems to promote olefin metathesis-type
reactions.
Fischer-carbenes, the Re-Ccarbene bond distance in 7a
(1.994(5) A) is elongated by 0.092, 0.037, and 0.027 A in com-
˚
˚
˚
parison with the Re-Cvinylidene bond length in 5b (1.902(6) A)
and the Re-Cbenzylidene bond lengths in [Re(dCHPh)-
(NO)2(PiPr3)2][BArF
]
4
˚
(1.957(3) A) and [Re(dCHPh)-
8,22
(NO)2(PCy3)2][BArF4] (1.967(7) A), respectively.
More-
˚
over, the reduced electrophilicity of the Fischer-carbene units
in 6a,b and 7a,b causes smaller No-Re-NO angles, which
leads to a higher stability when compared to the benzylidene
complexes [Re(dCHPh)(NO)2(PR3)2][BArF4] (R = Cy and
iPr). For instance, electrophilicity of the Ccarbene atoms of
the latter induces phosphine migration onto this atom at
elevated temperatures.8 Other reaction patterns such as the
acetonitrile-promoted alkylidene migration onto a nitrosyl
ligand and nitrosyl oxidation were also absent for 6a,b and
7a,b.11,22,24 Similarly, no catalytic activity was observed when
norbornene ROMP was attempted (under various reaction
conditions) with 6a,b or 7a,b, which imlies that alkylidene
complexes based on the [Re(PR3)2(NO)2]þ framework are not
suitable to promote olefin metathesis reactions.11,23
Conclusion
Reactions of the [Re(NO)2(PR3)2]þ cations (R = Cy 1a;
R = iPr 1b) with acetylene under various chemical condi-
tions are described. For instance, treatment of 1a and 1b with
Experimental Section
(22) Frech, C. M.; Blacque, O.; Schmalle, H. W.; Berke, H. Dalton
Trans. 2006, 4590.
General Procedures. All synthetic operations were conducted
in oven-dried glassware using a combination of glovebox (M.
Braun 150B-G-II), high-vacuum, and Schlenk techniques under
dinitrogen atmosphere. Solvents were freshly distilled under N2
by employing standard procedures and were degassed by free-
ze-thaw cycles prior to use. C6D6, C6D5Cl, THF-d8, and
methylenechloride-d2 were purchased from Armar, stored in a
Schlenk tube (Teflon tap) over sodium and P4O10, distilled, and
degassed prior to use. All the chemicals were purchased from
Aldrich Chemical Co. or Fluka. All reagents were used without
(23) Since the tungsten and molybdenum catalyst precursors
[M(Cl)2(NO)2(PR3)2] (M = Mo and W) show metathesis activity when
treated with 2 equiv of AlCl2Et, the catalytically active species of the
rhenium system cannot be of the same nature. Moreover, we could show
that carbene complexes composed of the cationic dinitrosyl bispho-
sphine fragment are not active in the olefin metathesis. It is therefore
questionable whether the [M(NO)2(PR3)2] (M = Mo and W) frame-
works remains intact in the catalytically active species of tungsten and
molybdenum catalysts.
(24) Stoe IPDS software for data collection, cell refinement, and data
reduction. Version 2.92; Stoe & Cie GmbH: Darmstadt, Germany, 1999.

Article
Organometallics, Vol. 28, No. 18, 2009 5339
further purification. Preparation of 1a and 1b was performed
according to the literature.26
Preparation of [Re(CdCH2)(NO)2(PR3)2][BArF4] (R = Cy 5a,
R = iPr 5b). To a methylene chloride solution (10 mL) of 4a
(20 mg, 0.025 mmol) or 4b (20 mg, 0.030 mmol) was added an
equimolar amount of [H(Et2O)][BArF4] at room temperature.
The yellow solution turned green with stirring for 5 min. The
volatiles were removed under reduced pressure, and the residue
was washed with pentane (2 ꢀ 10 mL) and dried under reduced
pressure. The pure compound was obtained as an olive green
solid. Yield:41.2 mg (0.024mmol; 97%) for5a and 41.5 mg (0.029
mmol; 95%) for 5b. Data for 5a: Found: C, 49.86; H, 5.01; N,
1.34. Calcd for C70H80BF24N2O2P2Re: C, 49.56; H, 4.75; N, 1.65.
IR (ATR; cm-1): ν 1751 (m, NO), 1652 (s, NO), 1612 (m, CdC).
1H NMR (500 MHz; CD2Cl2): 7.72(8 H, m, BArF4), 7.49(4 H, m,
BArF4), 5.82 (2 H, unresolved triplet, JPH = 2.3 Hz, Re-
(dCCH2)), 2.24-1.19 (36 H, m, P(C6H11)3). 13C{1H} NMR
(125.8 MHz; CD2Cl2): 322.52 (unresolved triplet, ReCdCH2)),
162.23(q, JBC = 49.9 Hz; ipso-B(ArF4)4), 135.31(m;o-B(ArF4)4),
128.98 (qq, JFC = 29.5, JBC = 2.9 Hz; m-B(ArF4)4), 125.07 (q,
JFC = 272.4 Hz ; CF3), 122.02 (s, ReCdCH2)), 117.86 (septet,
Physical Measurements. Elemental analyses were performed
on a Leco CHNS-932 analyzer at the University of Zurich,
Switzerland. 1H NMR, 13C{1H} NMR, and 31P{1H} NMR data
were recorded on a Bruker Avance DRX500 or on a Varian
Gemini 300 spectrometer. Chemical shifts are expressed in parts
per million (ppm) referenced to the deuterated solvent used. All
chemical shifts for 31P{1H} NMR data are reported downfield in
ppm relative to external 85% H3PO4 at 0.0 ppm. Signal patterns
are reported as follows: s, singlet; t, triplet; m, multiplet. IR
spectra were obtained by using KBr pellets or ATR methods
with a Bio-Rad FTS-45 FTIR spectrometer.
Preparation of [Re(CtCH)(NHOCHdCH)(NO)(PR3)2]-
[BArF4] (R = Cy 3a, R = iPr 3b). Benzene solutions (5 mL) of
1a (50 mg, 0.030 mmol) or 1b (50 mg, 0.035 mmol) were set under
an acetylene atmosphere and stirred at room temperature. After
several minutes a black oily precipitate began to form. After 1 h,
the volatiles were removed under reduced pressure and the
residue was washed with diethyl ether (2 ꢀ 10 mL) and dried
under reduced pressure. The pure compound was obtained as a
black solid. Yield: 35.4 mg (0.021 mmol; 52%) for 3a and
33.7 mg (0.023 mmol; 45%) for 3b. Data for 3a: Found: C,
54.98; H, 8.34; N, 3.33. Calcd for C38H67N2O2P2Re: C, 54.85; H,
8.12; N, 3.37. IR (ATR; cm-1): ν 1601 (m, HNO), 1725 (m, NO),
2090 (w, CtC). 1H NMR (500 MHz; THF-d8): 8.72 (br s, 1 H,
NHOCHdCH), 5.76 (1 H, dt, JHH = 7.6 Hz, JPH = 2.1 Hz,
NHOCHdCH), 5.02 (1 H, dt, JHH = 7.6 Hz, JPH = 5.8 Hz,
NHOCHdCH), 4.34 (1 H, unresolved t, JPH =3.6Hz,ReCtCH),
2.48-1.03 (66 H, m, P(C6H11)3). 31P{1H} NMR (121.5 MHz;
THF-d8): 36.51 (s, P(C6H11)3). Data for 3b: Found: C, 40.77; H,
7.51; N, 4.61. Calcd for C20H43N2O2P2Re: C, 40.60; H, 7.32; N,
4.73. IR (ATR; cm-1): ν 1600 (m, HNO), 1718 (m, NO), 2091
(w, CtC). 1H NMR (500 MHz; THF-d8): 8.90 (br s, 1 H,
NHOCHdCH), 5.69 (1 H, dt, JHH = 7.7 Hz, JPH = 2.2 Hz,
NHOCHdCH), 5.26 (1 H, dt, JHH = 7.8 Hz, JPH = 5.9 Hz, 1 H,
NHOCHdCH) 4.41 (1 H, t, JPH = 3.7 Hz, ReCtCH), 2.56 (6 H,
m, P{CH(CH3)2}3), 1.37 (m, 36H, P{CH(CH3)2}3). 31P{1H} NMR
(121.5 MHz; THF-d8): 43.02 (s, P{CH(CH3)2}3).
J
FC = 4.1 Hz; p-B(ArF4)), 36.15 (vt, JPC = 10.8 Hz, P(C6H11)3),
30.31, 27.63, 26.41 (s, P(C6H11)3). 31P{1H} NMR (121.5 MHz;
CD2Cl2): 24.81 (s, P(C6H11)3). Data for 5b: Found: C, 43.25; H,
4.13; N, 1.71. Calcd for C52H56BF24N2O2P2Re: C, 42.90; H, 3.88;
N, 1.92. IR (ATR; cm-1): ν 1753 (s, NO), 1650 (s, NO), 1609 (m,
CdC). 1H NMR (500 MHz; CD2Cl2): 7.69 (8 H, m, BArF4), 7.51
(4 H, m, BArF4), 5.57 (2 H, t, JPH = 2.8 Hz, Re(dCCH2)), 2.47 (6
H, m, P{CH(CH3)2}3), 1.29 (36 H, m, P{CH(CH3)2}3). 13C{1H}
NMR (125.8 MHz; CD2Cl2): 320.87 (t, JPC = 15.4 Hz, Re-
CdCH2)), 162.19 (q, JBC = 49.9 Hz; ipso-B(ArF4)), 135.32 (m;
o-B(ArF4)), 129.00 (qq, JFC = 29.4, JBC = 2.8 Hz; m-B(ArF4)),
125.12 (q, JFC = 272.2 Hz, CF3), 121.33 (s, ReCdCH2)), 117.86
(septet, JFC = 4.0 Hz; p-B(ArF4)), 26.76 (vt, JPC = 11.2 Hz,
P{CH(CH3)2}3), 19.48, 19.11 (s, P{CH(CH3)2}3). 31P{1H}
NMR (121.5 MHz; CD2Cl2): 31.92 (s, P{CH(CH3)2}3).
Preparation of [Re{C(CH3)[S(C6H5)]}(NO)2(PR3)2][BArF
]
4
(R = Cy 6a, R = iPr 6b). To a methylene chloride solution
(20 mL) of 5a (50 mg, 0.029 mmol) or 5b (50 mg, 0.034 mmol)
was added a slight excess (1.2 equiv) of thiophenol at room
temperature. The green solution turned dark violet while stirring
for 10 min. The volatiles were removed under reduced pressure,
and the residue was washed with pentane (3 ꢀ 10 mL) followed
by drying under reduced pressure. The pure compound was
obtained as a dark violet solid. Yield: 50.4 mg (0.028 mmol;
94%) for 6a and 51.1 mg (0.033 mmol; 95%) for 6b. Data for 6a:
Found: C, 50.62; H, 4.84; N, 1.23. Calcd for C76H86BF24N2-
O2P2ReS: C, 50.49; H, 4.80; N, 1.55. IR (ATR; cm-1): ν 1680 (m,
NO), 1631 (s, NO). 1H NMR (500 MHz; CD2Cl2): 7.73 (8 H, m,
BArF4), 7.58 (3 H, m, ReC(CH3)S(C6H5)), 7.52 (4 H, m, BArF4),
7.33 (2 H, m, ReC(CH3)(C6H5)), 3.23 (3 H, s, ReC(CH3)S-
(C6H5)), 2.20-1.23 (66 H, m, P(C6H11)3). 13C{1H} NMR (125.8
MHz; CD2Cl2): 300.53 (unresolved triplet, ReC(CH3)S(C6H5)),
162.09 (q, JBC = 49.8 Hz; ipso-B(ArF4)4), 148.16 (s, ReC(CH3)-
S(C6H5)), 135.27 (m, o-B(ArF4)4), 133.62, 132.54, 131.90, 131.00
(s, ReC(CH3)S(C6H5)), 128.98 (qq, JFC = 29.4, JBC = 2.8 Hz;
m-B(ArF4)4), 125.11 (q, JFC = 272.4 Hz ; CF3), 117.83 (septet,
JFC = 4.0 Hz; p-B(ArF4)), 123.05 (s, ReC(CH3)S(C6H5)), 45.76
(s, ReC(CH3)S(C6H5)), 36.10 (vt, JPC = 11.4 Hz, P(C6H11)3),
29.66, 29.34, 28.82, 27.32, 26.02 (s, P(C6H11)3). 31P{1H} NMR
(121.5 MHz; CD2Cl2): 9.98 (s, P(C6H11)3). Data for 6b: Found:
C, 44.37; H, 4.16; N, 1.72. Calcd for C58H62BF24N2O2P2ReS: C,
44.45; H, 3.99; N, 1.79. IR (ATR; cm-1): ν 1685 (m, NO), 1634
Preparation of [Re(CtCH)(NO)2(PR3)2] (R = Cy 4a, R =
iPr 4b). To a benzene solution (5 mL) of 1a (50 mg, 0.030 mmol) or
1b (50 mg, 0.035 mmol) were added successively an equimolar
amount of 2,6-bis(di-tBu)pyridine and an excess of acetylene at
room temperature. The dark red solution turned brown immedi-
ately. The volatiles were removed under reduced pressure, and the
residue was extracted with benzene (2 ꢀ 10 mL), filtrated over a
cotton pad, followed by the evaporation of the solvent under
reduced pressure. The pure compound was obtained as an orange
solid. Yield: 23.6 mg (0.029 mmol; 83%) for 4a and 16.8 mg (0.028
mmol; 80%) for 4b. Data for 4a: Found: C, 54.98; H, 8.34; N, 3.33.
Calcd for C38H67N2O2P2Re: C, 54.85; H, 8.12; N, 3.37. IR (ATR;
cm-1): ν 1581 s, NO), 1621 (s, NO). 1H NMR (500 MHz; C6H6):
4.14 (1 H, br s, JPH = 3.9 Hz, ReCtCH), 2.42-1.25 (66 H, m,
P(C6H11)3). 13C{1H} NMR (125.8 MHz; C6D6): 127.78 (t, JPC
=
2.1 Hz, ReCtCH), 111.89 (t, JPC = 19.2 Hz, ReCtCH), 36.39
(vt, JPC = 12.5 Hz, P(C6H11)3), 30.34 (s, P(C6H11)3), 28.26(vt,
JPC = 5.4 Hz, P(C6H11)3), 27.02 (s, P(C6H11)3). 31P{1H} NMR
(121.5 MHz; C6H6): 20.62 (s, P(C6H11)3). Data for 4b: Found: C,
40.77; H, 7.51; N, 4.61. Calcd for C20H43N2O2P2Re: C, 40.60; H,
7.32; N, 4.73. IR (ATR; cm-1): ν 1576 (s, NO), 1618 (s, NO). 1H
NMR (500 MHz; C6H6): 4.04 (1 H, t, JPH = 4.2 Hz, ReCtCH),
2.43 (6 H, m, P{CH(CH3)2}3), 1.33 (m, 36H, P{CH(CH3)2}3).
13C{1H} NMR (125.8 MHz; C6D6): 126.32 (t, JPC = 2.2 Hz,
1
(s, NO). H NMR (500 MHz; CD2Cl2): 7.71 (8 H, m, BArF4),
7.57 (3 H, m, RedC(CH3)S(C6H5)), 7.54 (4 H, m, BArF4), 7.33
(2 H, m, ReC(CH3)S(C6H5)), 3.33 (3 H, s, RedC(CH3)S-
(C6H5)), 2.57 (6 H, m, P{CH(CH3)2}3), 1.29 (36 H, m, P{CH-
(CH3)2}3). 13C{1H} NMR (125.8 MHz; CD2Cl2): 304.65 (t,
JPC = 3.5 Hz, ReC(CH3)S(C6H5)), 162.08 (q, JBC = 49.9 Hz;
ipso-B(ArF4)4), 148.47 (s, ReC(CH3)S(C6H5)), 135.22 (m,
ReCtCH), 111.71 (t, JPC = 18.9 Hz, ReCtCH), 26.26 (vt, JPC
=
12.8 Hz, P{CH(CH3)2}3), 19.84 (s, P{CH(CH3)2}3). 31P{1H}
NMR (121.5 MHz; C6H6): 26.46 (s, P{CH(CH3)2}3).
(25) Coppens, P.; Leiserowitz, L.; Rabinovich, D. Acta Crystallogr.
1965, 18, 1035.
(26) Sheldrick, G. M. Acta Crystallogr. Sect. A 2008, 112.
o-B(ArF ) ), 133.17, 132.50, 132.13, 131.00 (s, ReC(CH3)S(C6-
4 4
H5)), 129.11 (qq, JFC = 29.5, JBC = 2.8 Hz; m-B(ArF ) ), 125.06
4 4

5340 Organometallics, Vol. 28, No. 18, 2009
Table 1. Crystallographic Data of 4b, 5b, and 7a
Frech et al.
parameter
4b
5b
7a
chemical formula
fw [g mol-1
C20H43N2O2P2Re
591.71
C52.125 H56.25BCl0.25F24 N2 O2 P2 Re
1466.56
C167H208B2F48N4O4P4Re2Se2
3923.21
]
cryst habit, color
cryst dimens [mm]
cryst syst
plate, red
0.35 ꢀ 0.30 ꢀ 0.10
monoclinic
P21/c
11.8793(8)
13.7535(9)
15.6869(11)
90
95.817(8)
90
2549.8(3)
4
123(2)
block, green
0.33 ꢀ 0.29 ꢀ 0.22
triclinic
plate, violet
0.26 ꢀ 0.19 ꢀ 0.07
triclinic
space group
˚
P1
P1
a [A]
12.3890(7)
19.2742(11)
26.7543(15)
76.765(6)
85.778(7)
89.584(7)
6201.7(6)
4
183(2)
1.571
2.133
0.0509, 0.1278
14.4760(14)
17.1882(16)
20.163(2)
70.232(11)
74.210(11)
83.273(11)
4541.3(9)
1
183(2)
1.434
1.867
0.0442, 0.1016
˚
b [A]
˚
c [A]
R [deg]
β [deg]
γ [deg]
3
˚
V [A ]
Z
T [K]
Dcalcd [gcm-3
]
1.541
4.907
0.0264, 0.663
μ [mm-1
]
R1a,
wR2b (I > 2σ(I))
R1a,
0.0396, 0.0683
0.0710, 0.1355
0.0733, 0.1076
wR2b (all data)
P
P
P
P
a R(F) =
Fo|-|Fc
|Fo|. b Rw(F2) = [ w(Fo2 - Fc2)2]/[ w(Fo2)2]1/2
.
(q, JFC = 272.5 Hz, CF3), 117.92 (septet, JFC = 4.0 Hz; p-B(ArF )),
was cooled to 123(2) K for 4b and to 183(2) K for 5b and 7a.
Crystals of 4b, 5b, and 7a protected in hydrocarbon oil were
selected using a polarizing microscope. The crystals were
mounted on a tip of a glass fiber and immediately transferred
to the goniometer of an imaging plate detector system (Stoe
IPDS diffractometer) and cooled to 183(2) K using an Oxford
Cryogenic System. The crystal-to-image distance was set to
50 mm (θmax = 30.245ꢀ) for 4b, 70 mm (θmax = 25.90ꢀ) for
5b, and 60 mm (θmax = 27.95ꢀ) for 7a. The j-oscillation scan
modes were applied for the intensity measurement. For the cell
parameter refinement for 4b, 5b, and 7a, 7997, 7996, and 8000
reflections were selected out of the whole limiting sphere. A total
of 29 609, 54 386, and 72 540 diffraction intensities were col-
lected,24 of which 7371, 22 563, and 20 147 were independent
(Rint = 0.0471, 0.0536, and 0.0681) after data reduction. Nu-
merical absorption correction25 based on 15, 16, and 9 crystal
faces was applied with the FACEitVIDEO and XRED pro-
grams.24 The structure was solved by the Patterson method
using the SHELXS97 program package.26 Interpretation of the
difference Fourier maps, preliminary plot generations, and
checking for higher symmetry were performed with the PLA-
TON program27 and the implemented in the LEPAGE pro-
gram.28 All heavy atoms were refined (SHELXL97)26 using
anisotropic displacement parameters. Positions of H atoms were
calculated after each refinement cycle (riding model). The
structural plots were generated using the ORTEP program.29
4
46.23 (s, ReC(CH3)S(C6H5)), 26.59 (vt, JPC = 14.5 Hz, P{CH-
(CH3)2}3), 19.54, 19.14 (s, P{CH(CH3)2}3). 31P{1H} NMR (121.5
MHz; CD2Cl2): 20.00 (s, P{CH(CH3)2}3).
Preparation of [Re{C(CH3)[Se(C6H5)]}(NO)2(PR3)2][BArF
]
4
(R = Cy 7a, R = iPr 7b). To a methylene chloride solution
(20 mL) of 5a (50 mg, 0.029 mmol) or 5b (50 mg, 0.034 mmol) was
added a slight excess (1.2 equiv) of benzoselenol at room tempera-
ture. The green solution turned dark violet while stirring for
10 min. The volatiles were removed under reduced pressure, and
the residue was washed with pentane (3 ꢀ 10 mL) followed by
drying under reduced pressure. The pure compound was obtained
as a dark violet solid. Yield: 51.4 mg (0.028 mmol; 94%) for 5a and
52.4 mg (0.033 mmol; 95%) for 7b. Data for 7a: Found: C, 49.50;
H, 4.39; N, 1.35. Calcd for C76H86BF24N2O2P2ReSe: C, 49.25; H,
4.68; N, 1.51. IR (ATR; cm-1): ν 1696 (m, NO), 1635 (s, NO). 1H
NMR (500 MHz; CD2Cl2): 7.72 (8 H, m, BArF4), 7.57 (3 H, m,
ReC(CH3)Se(C6H5)), 7.54 (4 H, m, BArF4), 7.45 (2 H, m, ReC-
(CH3)Se(C6H5)), 3.38 (3 H, s, ReC(CH3)Se(C6H5)), 2.14-1.23
(66 H, m, P(C6H11)3). 13C{1H} NMR (125.8 MHz; CD2Cl2):
300.63 (unresolved triplet, ReC(CH3)Se(C6H5)), 162.16 (q,
JBC = 49.9 Hz; ipso-B(ArF4)4), 148.47 (s, ReC(CH3)Se(C6H5)),
135.25 (m, o-B(ArF4)4), 133.50, 131.01, 130.86, (s, ReC(CH3)Se-
(C6H5)), 129.14 (qq, JFC = 29.4, JBC = 2.9 Hz; m-B(ArF4)4),
125.16 (q, JFC = 272.4 Hz, CF3), 117.95 (septet, JFC = 4.1 Hz;
p-B(ArF4)), 48.56 (s, ReC(CH3)Se(C6H5)), 36.19 (vt, JPC
=
11.4 Hz, P(C6H11)3), 29.68, 29.27, 28.84, 27.26, 26.02 (s,
P(C6H11)3). 31P{1H} NMR (121.5 MHz; CD2Cl2): 7.33 (s,
P(C6H11)3). Data for 7b: Found: C, 44.37; H, 4.16; N, 1.72. Calcd
for C58H62BF24N2O2P2ReSe: C, 43.19; H, 3.87; N, 1.74. IR (ATR;
cm-1): ν 1685 (m, NO), 1634 (s, NO). 1H NMR (500 MHz;
CD2Cl2): 7.71 (8 H, m, BArF4), 7.57 (3 H, m, RedC(CH3)Se-
(C6H5)), 7.54 (4 H, m, BArF4), 7.33 (2 H, m, ReC(CH3)Se(C6H5)),
3.33 (3 H, s, RedC(CH3)Se(C6H5)), 2.51(6H, m, P{CH(CH3)2}3),
1.25 (36 H, m, P{CH(CH3)2}3). 13C{1H} NMR (125.8 MHz;
CD2Cl2): 306.32 (t, JPC = 3.5 Hz, ReC(CH3)Se(C6H5)), 162.14
(q, JBC = 49.9 Hz; ipso-B(ArF4)4), 148.47 (s, ReC(CH3)Se(C6H5)),
135.25 (m, o-B(ArF4)4), 132.35, 131.29, 130.96 (s, ReCHSe-
(C6H5)), 129.18 (qq, JFC = 29.5, JBC = 2.9 Hz; m-B(ArF4)4),
125.23 (q, JFC = 272.5 Hz, CF3), 117.98 (septet, JFC = 4.2 Hz;
p-B(ArF4)), 49.06 (s, ReC(CH3)Se(C6H5)), 26.76 (vt, JPC = 14.5
Hz, P{CH(CH3)2}3), 19.50, 19.10 (s, P{CH(CH3)2}3). 31P{1H}
NMR (121.5 MHz; CD2Cl2): 17.85 (s, P{CH(CH3)2}3).
Acknowledgment. This work was funded by the Swiss
National Science Foundation (SNSF) and the University
of Zurich.
Supporting Information Available: CIF files containing X-ray
crystallographic data for complexes 4b (CCDC-606740), 5b
(CCDC-606741), and 7a (CCDC-606742) and energies and Carte-
sian coordinates of all calculated intermediates and transition
states. This material is available free of charge from the Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif, at http://pubs.acs.org, or from the author.
(27) (a) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7. (b) Spek, A. L.
Acta Crystallogr. Sect. D 2009, 148.
(28) Le Page, Y. J. Appl. Crystallogr. 1987, 20, 264.
(29) Johnson C. K. ORTEPII. Report ORNL-5138; Oak Ridge
National Laboratory: Oak Ridge, TN, 1976.
X-ray Diffraction Analysis of 4b, 5b, and 7a. X-ray diffraction
studies were performed on a Stoe IPDS diffractometer, where it