Enforced η1-fluorenyl coordination to rhodium(I) with the [FluPPh2NPh]- ligand

Article abstract of DOI:10.1021/om0605377

The fluorenyl-phosphazene ligand 2 has been prepared and coordinated to the Rh^l(nbd) fragment. X-ray analyses and DFT calculations substantiate the preference of the resulting complex 3 for κ²-N,C over η⁵-fluorenyl coordin

Full text of DOI:10.1021/om0605377

Organometallics 2006, 25, 4927-4930
4927
Enforced η1-Fluorenyl Coordination to Rhodium(I) with the
[FluPPh2NPh]- Ligand
Christelle Freund,† Noe´mi Barros,‡ Heinz Gornitzka,† Blanca Martin-Vaca,†
Laurent Maron,*,‡ and Didier Bourissou*,†
Laboratoire He´te´rochimie Fondamentale et Applique´e du CNRS (UMR 5069) UniVersite´ Paul Sabatier,
118 Route de Narbonne, F-31062 Toulouse Cedex 09, France, and LNMO (Laboratoire de Nanophysique,
Magne´tisme et Optoe´lectronique), INSA, UniVersite´ Paul Sabatier, 135 AVenue de Rangueil,
F-31077 Toulouse Cedex, France
ReceiVed June 20, 2006
Chart 1. Structure of the Heteroallyl Ligands A-D
Summary: The fluorenyl-phosphazene ligand 2 has been pre-
pared and coordinated to the RhI(nbd) fragment. X-ray analyses
and DFT calculations substantiate the preference of the re-
sulting complex 3 for κ2-N,C oVer η5-fluorenyl coordination.
Despite the associated geometry constraint, the coordina-
tion of the short phosphazene sidearm is shown to enforce
η1-fluorenyl coordination.
Introduction
a phosphazene sidearm, and the presence of this strongly do-
nating pendant group10 can be expected to influence dramatic-
ally the bonding mode of the Cp-type ligand. Here we report
the synthesis and structural characterization of a fluorenyl-phos-
phazene ligand and its ensuing RhI(nbd) complex. X-ray analy-
ses and DFT calculations substantiate the preference of this sys-
tem for κ2-N,C over η5-fluorenyl coordination.11 Despite the
associated geometry constraint, the coordination of the short
phosphazene sidearm is shown to enforce η1-fluorenyl coordina-
tion.12
The coordination properties of 1-aza-2-phospha(V)allyl ligands
A have attracted considerable interest over the last 15 years
(Chart 1).1-6 Compared with their 1,3-diaza-allyl (the so-called
amidinates) B, 1,3-diaza-2-phospha(V)allyl C, and 2-phospha-
(V)allyl D analogues, ligands A combine two different donor
atoms (N and C) and potentially induce electronic as well as
steric desymmetrization of the metal environment. Introduction
of functional groups on the central NPC skeleton can further
influence their coordination properties, as nicely illustrated by
the incorporation of an aryl group7 or a second phosphinimino
group8 at carbon or a methoxycarbonyl group at nitrogen.9
With this in mind, we recently became interested in the incor-
poration of the carbon atom of ligands A into a Cp-type ring
(such as cyclopentadienyl, indenyl, fluorenyl). The resulting lig-
ands A′ can also be regarded as Cp-type derivatives featuring
Results and Discussion
The Staudinger reaction appeared a straightforward and
efficient route to the desired bifunctional ligand 2, which was
obtained in 56% isolated yield by reacting the readily available
fluorenyl-diphenylphosphine 113 with phenyl azide14 in toluene
at room temperature (Scheme 1). According to 1H and 13C NMR,
* To whom correspondence should be addressed. Fax +33 (0)5 61 55
82 04. Tel +33 (0)5 61 55 77 37. E-mail: dbouriss@chimie.ups-tlse.fr.
† Laboratoire He´te´rochimie Fondamentale et Applique´e du CNRS.
‡ LNMO, INSA.
(1) For general reviews, see: (a) Izod, K. Coord. Chem. ReV. 2002, 227,
153-173. (b) Steiner, A.; Zacchini, S.; Richards, P. I. Coord. Chem. ReV.
2002, 227, 193-216.
(2) For Li complexes, see: (a) Lo´pez-Ortiz, F.; Pela´ez-Arango, E.;
Tejerina, B.; Pe´rez-Carren˜o, E.; Garc´ıa-Granda, S. J. Am. Chem. Soc. 1995,
117, 9972-9981. (b) Mu¨ller, A.; Neumu¨ller, B.; Dehnicke, K. Chem. Ber.
1996, 129, 253-257. (c) Hitchcock, P. B.; Lappert, M. F.; Wang, Z.-X.
Chem. Commun. 1997, 1113-1114. (d) Hitchcock, P. B.; Lappert, M. F.;
Uiterweerd, P. G. H. J. Chem. Soc., Dalton Trans. 1999, 3413-3418. (e)
Mu¨ller, A.; Neumu¨ller, B.; Dehnicke, K. Z. Anorg. Allg. Chem. 2002, 628,
100-106. (f) Price, R. D.; Ferna´ndez, I.; Ruiz-Go´mez, G.; Lo´pez-Ortiz,
F.; Davidson, M. G.; Cowan, J. A.; Howard, J. A. K. Organometallics 2004,
23, 5934-5938. (g) Lo´pez-Ortiz, F. Curr. Org. Synth. 2006, 3, 187-214.
(3) For Zr and Ti complexes, see: (a) Sarsfield, M. J.; Thornton-Pett,
M.; Bochmann, M. J. Chem. Soc., Dalton Trans. 1999, 3329-3330. (b)
Said, M.; Thornton-Pett, M.; Bochmann, M. J. Chem. Soc., Dalton Trans.
2001, 2844-2849.
(4) For Rh and Ir complexes, see: (a) Imhoff, P.; Nefkens, S. C. A.;
Elsevier, C. J.; Goubitz, K.; Stam, C. H. Organometallics 1991, 10, 1421-
1431. (b) Imhoff, P.; van Asselt, R.; Ernsting, J. M.; Vrieze, K.; Elsevier,
C. J.; Smeets, W. J. J.; Spek, A. L.; Kentgens, A. P. M. Organometallics
1993, 12, 1523-1536.
(5) For Ni, Pd, and Pt complexes, see: (a) Avis, M. W.; Vrieze, K.;
Kooijman, H.; Veldman, N.; Spek, A. L.; Elsevier, C. J. Inorg. Chem. 1995,
34, 4092-4105. (b) Avis, M. W.; Vrieze, K.; Ernsting, J. M.; Elsevier, C.
J.; Veldman, N.; Spek, A. L.; Katti, K. V.; Barnes, C. L. Organometallics
1996, 15, 2376-2392. (c) Masuda, J. D.; Wei, P.; Stephan, D. W. Dalton
Trans. 2003, 3500-3505.
(6) For Sn, Ge, and Pb complexes, see: (a) Hitchcock, P. B.; Lappert,
M. F.; Wang, Z.-X. J. Organomet. Chem. 2006, 691, 2748-2756. (b) Leung,
W. P.; Wong, K. W.; Wang, Z. X.; Mak, T. C. W. Organometallics 2006,
25, 2037-2044.
(7) Said, M.; Thornton-Pett, M.; Bochmann, M. Organometallics 2001,
20, 5629-5635.
(8) Bibal, C.; Smurnyy, Y. D.; Pink, M.; Caulton, K. G. J. Am. Chem.
Soc. 2005, 127, 8944-8945.
(9) Ferna´ndez, I.; AÄ lvarez Gutie´rrez, J. M.; Kocher, N.; Leusser, D.;
Stalke, D.; Gonza´lez, J.; Lo´pez-Ortiz, F. J. Am. Chem. Soc. 2002, 124,
15184-15185.
(10) For selected references, see: (a) Reetz, M. T.; Bohres, E.; Goddard,
R. Chem. Commun. 1998, 935-936. (b) Sauthier, M.; Fornie´s-Ca´mer, J.;
Toupet, L.; Re´au, R. Organometallics 2000, 19, 553-562. (c) Spencer, L.
P.; Altwer, R.; Wie, P.; Gelmini, L.; Gauld, J.; Stephan, D. W. Organo-
metallics 2003, 22, 3841-3854. (d) Kocher, N.; Leusser, D.; Murso, A.;
Stalke, D. Chem. Eur. J. 2004, 10, 3622-3631. (e) Boubekeur, L.; Ricard,
L.; Me´zailles, N.; Le Floch, P. Organometallics 2005, 24, 1065-1074. (f)
Co, T. T.; Shim, S. C.; Cho, C. S.; Kim, T.-J.; Kang, S. O.; Han, W.-S.;
Ko, J.; Kim, C.-K. Organometallics 2005, 24, 4824-4831.
(11) Related Cp-phosphazene zirconium and lutetium complexes were
reported to adopt η5 coordination with phosphazenefmetal interaction: (a)
Truflandier, L.; Marsden, C. J.; Freund, C.; Martin-Vaca, B.; Bourissou,
D. Eur. J. Inorg. Chem. 2004, 1939-1947. (b) Rufanov, K. A.; Petrov, A.
R.; Kotov, V. V.; Laquai, F.; Sundermeyer, J. Eur. J. Inorg. Chem. 2005,
3805-3807.
(12) For recent reviews on η1-fluorenyl and η1-indenyl complexes, see:
(a) Alt, H. G.; Samuel, E. Chem. Soc. ReV. 1998, 27, 323-329. (b)
Stradiotto, M.; McGlinchey, M. J. Coord. Chem. ReV. 2001, 219-221, 311-
378. (c) Kirillov, E.; Saillard, J.-Y.; Carpentier, J.-F. Coord. Chem. ReV.
2005, 249, 1221-1248.
10.1021/om0605377 CCC: $33.50 © 2006 American Chemical Society
Publication on Web 08/26/2006

4928 Organometallics, Vol. 25, No. 20, 2006
Notes
Scheme 1. Synthesis and Coordination of the
Fluorenyl-phosphazene 2
Chart 2. CC Bond Lengths within the Central
Five-Membered Rings of the Fluorenyl Moieties in 2 and 3
plex 3 was isolated in 90% yield following extraction with
dichloromethane. The 31P NMR spectrum of 3 consists of a
doublet signal (JPRh ) 16.2 Hz) deshielded by 16.3 ppm
1
compared to that of 2. The H NMR spectrum features the
typical signals for the (FluPPh2NPh)- and nbd ligands in a 1:1
ratio. While the mass and 1H and 31P NMR spectra are consistent
with the general formula [(FluPPh2NPh)Rh(nbd)], they do not
reveal the coordination mode of the (FluPPh2NPh)- ligand. In
13C NMR, the C9 atom resonates at 33.9 ppm as a doublet of
1
doublets (1JCP ) 109.3 and JCRh ) 10.5 Hz), while the other
ligand 2 adopts in solution the tautomeric phosphazene form
(NdP-CH) rather than the P-ylide form (NH-PdC).15 Indeed,
the CH signal observed at 49.8 ppm in the13C NMR spectrum
is attributed to the central C9 atom of the fluorenyl moiety and
Flu quaternary carbon atoms appear as singlets at more than
130 ppm. This suggests a low Flu hapticity, which was
unambiguously confirmed by an X-ray diffraction study (Figure
1b). The rhodium center of 3 adopts a square planar arrange-
ment, the (FluPPh2NPh)- ligand being coordinated to the metal
center via the nitrogen and C9 atoms. The four-membered
ring NPCRh is nearly planar (maximum deviation from the
best fit plane of 0.18 Å for P). The Rh-N and Rh-C9 bond
lengths (2.123 and 2.188 Å, respectively) are comparable to
those observed for the related 1-aza-2-phospha(V)allyl complex
(H2CPPh2NAr)Rh(cod).4a This κ2-N,C coordination is accom-
panied by a contraction of the PC distance (from 1.856 Å in 2
to 1.768 Å in 3), an elongation of the PN distance (from 1.567
Å to 1.620 Å), and a noticeable decrease in the NPC bond angle
(from 116.7° to 100.5°), revealing the delocalized character of
the anionic ligand and the geometry constraint of the ensuing
complex.16 Notably, the CC bond lengths of the central five-
membered ring of the fluorenyl moiety do not equalize upon
coordination and remain very similar to those observed for 2
(Chart 2). This observation suggests that the fluorenyl π-system
remains fairly localized, in agreement with an η1-Flu coordina-
tion. This unusual bonding situation is further substantiated by
associated in the 1H NMR spectrum to a doublet signal (2JHP
)
24.0 Hz) at 5.09 ppm. Single crystals of 2 were obtained at
-25 °C from a toluene/THF solution. X-ray diffraction analysis
indicated that the same form is adopted in the solid state, since
the hydrogen atom at C9 could be located and refined without
any constraint (Figure 1a).
The coordination properties of the (FluPPh2NPh)- ligand
toward Rh(I) were then investigated. After deprotonation with
n-butyllithium, 2 was reacted with 0.5 equiv of [Rh(µ-Cl)(nbd)]2
(nbd ) norbornadiene) in tetrahydrofuran. The resulting com-
the noticeable pyramidalization of the C9 atom (∑C9R
)
349.8°)17 and by the remoteness of the other CFlu atoms from
the rhodium center (RhC distances > 3 Å). To the best of our
knowledge, complex 3 is the first η1-fluorenyl rhodium adduct
to be structurally characterized, and its selective formation over
the corresponding η5-complex 3′ (Figure 2) illustrates the ability
of the short phosphazene sidearm to enforce low Flu hapticity,
despite the associated geometry constraint.18,19
To gain further insight into the low hapticity of the fluorenyl
ring encountered in complex 3, ab initio calculations20 were
performed at the DFT level of theory (Table 1). The full
(13) Baiget, L.; Bouslikhane, M.; Escudie´, J.; Cretiu Nemes, G.; Silaghi-
Dumitrescu, I.; Silaghi-Dumitrescu, L. Phosphorus, Sulfur, Silicon 2003,
178, 1949-1961.
(14) Murata, S.; Abe, S.; Tomioka, H. J. Org. Chem. 1997, 62, 3055-
3061.
(15) The opposite situation was encountered in the related
Cp′PMe2NAd ligand.11b
(16) The disymmetric nature of the (FluPPh2NPh)- ligand results in the
nonequivalence of the two nbd carbon-carbon double bonds, which is
apparent both in NMR and in X-ray. As previously observed for the related
1-aza-2-phospha(V)allyl complex (H2CPPh2NAr)Rh(cod),4a the higher trans
influence of the carbon compared to the nitrogen atom noticeably affects
the bond distances from the metal center to the midpoints of the CC double
bonds (Rh-M of 2.040 and 1.981 Å in trans position to the carbon and
nitrogen, respectively), but practically not those of the CC double bonds
(1.380 vs 1.388 Å).
Figure 1. Molecular views of 2 (a) and 3 (b) in the solid state
(hydrogen atoms are omitted for clarity). Selected bond lengths
(Å) and angles (deg): 2: P1-N1 1.5679(19); P1-C9 1.856(2);
N1-C9 1.394(3); N1-P1-C9 116.70(10); C10-C9-C11 102.46-
(18); C10-C9-P1 109.99(15); C11-C9-P1 113.89(15). 3: Rh1-
N1 2.123(2); Rh1-C9 2.188(3); P1-N1 1.620(2); P1-C9 1.768(3);
N1-Rh1-C9 74.40(9); N1-P1-C9 100.51(12); C10-C9-C11
105.2(2); C10-C9-P1 118.2(2); C11-C9-P1 126.4(2).

Notes
Organometallics, Vol. 25, No. 20, 2006 4929
To highlight the tendency of the (FluPPh2NPh)- ligand to
favor low hapticity, the related η5-complex 3′ has also been
optimized. Its structure is represented in Figure 2, and its key
geometrical parameters are listed in Table 1. Compared with
the η1-complex 3, the phosphazene sidearm has rotated around
the C9P bond so that the nitrogen atom no longer interacts with
the metal center (NRh distance of 3.88 Å). The C9Rh bond
length (2.180 Å) is very similar to that calculated for 3, and
the η5 coordination of the fluorenyl is unambiguously indicated
by the close contacts predicted between the metal center and
the four other carbon atoms of the central ring (RhC(q)Flu dis-
tances ranging from 2.32 to 2.42 Å). Notably, the change of
the fluorenyl hapticity from η1 to η5 is also accompanied by
noticeable strain relief of the NPC9 bond angle (106.7°), by
the equalization of CC bond lengths within the central five-
membered ring (with a maximum deviation of 0.02 Å from the
average value of 1.45 Å), and by the planarization of the C9
environment (∑C9R ) 355.9°). In agreement with the experi-
mental observations, the η5-complex 3′ has been calculated to
be significantly less stable than the η1-complex 3. The rather
large energetic difference predicted between the two isomeric
complexes (16.7 kcal‚mol-1) substantiates the strong influence
of the phosphazene sidearm introduced on the fluorenyl, the
phosphazene-rhodium interaction apparently being strong
enough to compensate for the otherwise unfavorable η1 coor-
dination.
Figure 2. Optimized structure for the η5-complex 3′.
substitution pattern of the NPC ligand was conserved in order
to reliably take into account electronic and steric factors.
Accordingly, the key features of this complex could be very
well reproduced (largest deviations of only 0.04 Å for the NP
and PC bond lengths and 3° for the NPC angle), indicating the
capability of the method in describing this kind of system.
The bonding situation in κ2-N,C complexes derived from
1-aza-2-phosphaallyl ligands A has been described by consider-
ing the two limiting structures a and b (Chart 3).3a,4a On the
basis of the geometric data, complex 3 is accordingly best
described by the phosphazene/alkyl structure a, with only minor
contribution of the amido/phosphorus ylide form b. A more
precise description could be obtained from a natural bonding
analysis (NBO),21 especially regarding the nature of the RhC9
bond and the delocalization of the two nitrogen lone pairs
(referred to as in-plane and out-of-plane, according to their
orientation relative to the NPCRh metallacycle). As expected
from the difference in electronegativity, the Rh-C9 bond was
predicted to be polarized, but the 65%(C9)/35%(Rh) distribution
indicates noticeable covalent character, in agreement with form
a. At the second-order donor-acceptor interaction level, the
nitrogen in-plane lone pair is predicted to be delocalized over
empty orbitals centered at both rhodium (50 kcal‚mol-1) and
phosphorus (20 kcal‚mol-1). In addition, the nitrogen out-of-
plane lone pair is found to be delocalized into the phenyl ring
(roughly 50 kcal‚mol-1), in agreement with the orientation of
the phenyl ring relative to the metallacycle (twist angle of 27.1°).
This NBO analysis clearly stresses the contribution of weak
donor-acceptor interactions in complex 3, resulting in a rather
complicated bonding situation that is not comprehensively
represented by Lewis structures a and b.
Conclusion
In conclusion, a fluorenyl-phosphazene ligand has been
prepared and coordinated to the RhI(nbd) fragment. Despite the
associated geometry constraint, the coordination of the short
phosphazene sidearm has been demonstrated by X-ray analyses
and DFT calculations to enforce low hapticity, giving thereby
access to unusual η1-fluorenyl coordination.
Experimental Section
General Procedures. All reactions were performed using stand-
ard Schlenk techniques under an argon atmosphere. NMR spectra
were recorded on Bruker Avance 300 or 400 spectrometers. 31P,
1H, and 13C chemical shifts are expressed with a positive sign, in
parts per million, relative to external 85% H3PO4 and TMS. Unless
otherwise stated, NMR was recorded at 293 K. Elemental analyses
were performed using a Perkin-Elmer 2400 (II) elemental analyzer.
Mass spectra were recorded on a Hewlett-Packard 5989.
Materials and Methods. THF and toluene were dried under
sodium and distilled prior to use. All organic reagents were obtained
from commercial sources and used as received. [Rh(µ-Cl)(nbd)]2
was purchased from Strem Chemicals, stocked in a glovebox, and
used without further purification. The fluorenyl-diphenylphosphine
113 and phenyl azide14 were prepared according to literature
procedures.
Preparation of 2 from 1. A degassed solution of PhN3 (0.58 g,
4.8 mmol) in toluene (10 mL) was added at room temperature to
a degassed suspension of Ph2PFlu (1.34 g, 4.4 mmol) in toluene
(30 mL). After stirring for 5 h, the solvent and excess of PhN3
were eliminated under vacuum to yield a pale yellow solid. Cooling
a solution of 2 in toluene/THF to -25 °C yielded 1.075 g of pale
yellow crystals (56%). 31P{1H} NMR (121.4 MHz, C6D6): δ 7.8
(17) The ylidic carbon center is planar in fluorenylidenephosphoranes:
(a) Burford, N.; Clyburne, J. A. C.; Sereda, S. V.; Cameron, T. S.; Pincock,
J. A.; Lumsden, M. Organometallics 1995, 14, 3762-3767. (b) Brady, E.
D.; Hanusa, T. P.; Pink, M.; Young, V. G., Jr. Inorg. Chem. 2000, 39,
6028-6037.
(18) Introduction of a pendant phosphine sulfide has recently allowed
for the first structural characterization of an η1-indenyl rhodium complex:
(a) Wechsler, D.; McDonald, R.; Ferguson, M. J.; Stradiotto, M. Chem.
Commun. 2004, 2446-2447. (b) Wechsler, D.; Myers, A.; McDonald, R.;
Ferguson, M. J.; Stradiotto, M. Inorg. Chem. 2006, 45, 4562-4570.
(19) For a rare example of η5-fluorenyl rhodium complex, see: Doppiu,
A.; Englert, U.; Salzer, A. Chem. Commun. 2004, 2166-2167.
(20) See Experimental Section and Supporting Information for details.
(21) Reed, A. E.; Curtiss, L. A.; Weinhold, F. Chem. ReV. 1988, 88,
899-926.
1
3
ppm; H NMR (300 MHz, C6D6): δ 7.68 (d, JH,H ) 7.5 Hz, 2H,
H
1,8), 7.42 (m, 4H, H15,19), 7.34 (d, 3JH,H ) 7.5 Hz, 2H, H4,5), 7.17
(m, 2H, H22,24), 7.10 (m, 2H, H3,6), 7.05 (m, 2H, H21,25), 7.00 (m,
2H, H2,7), 6.96 (m, 2H, H17), 6.86 (m, 4H, H16,18), 6,79 (m, 1H,
H23), 5.09 ppm (d, 1H, 2JH,P ) 24.0 Hz, H9). 13C{1H} NMR (75.5
2
3
MHz, C6D6): δ 151.7 (d, JC,P ) 3.0 Hz, C20), 142.2 (d, JC,P
)
)
2
2
4.5 Hz, C11,12), 139.7 (d, JC,P ) 3.8 Hz, C10,13), 132.4 (d, JC,P

4930 Organometallics, Vol. 25, No. 20, 2006
Table 1. Selected Bond Lengths and Angles (in Å and deg, respectively) for Derivatives 2, 3, and 3′
Notes
N-Rh
C9-Rh
N-Rh-C9
N-P
P-C9
N-P-C9
∑C9R
2 (X-ray)
3 (X-ray)
3a
1.567(9)
1.620(2)
1.662
1.856(2)
1.768(3)
1.803
116.70(10)
100.51(12)
97.3
326.3
349.8
346.3
355.9
2.123(2)
2.117
3.878
2.188(3)
2.186
2.180
74.40(9)
74.4
43.8
3′a
1.615
1.818
106.7
a Predicted at the DFT(B3PW91) level of theory.
Chart 3. Limiting Structures for K2-N,C Complexes
crystal size 0.2 × 0.2 × 0.5 mm3, 10 508 reflections collected
(3843 independent, Rint ) 0.0423), 302 parameters, R1 [I > 2σ(I)]
) 0.0440, wR2 [all data] ) 0.1130, largest diff peak and hole
0.314 and -0.302 e Å-3. 3: C38H31NPRh, M ) 635.52, triclinic,
space group P1h, a ) 9.6858(8) Å, b ) 11.6141(10) Å, c ) 13.6750-
(11) Å, R ) 106.9820(10)°, â ) 94.884(2)°, γ ) 96.293(2)°, V
)1451.2(2) Å3, Z ) 2, µ(Mo KR) ) 0.672 mm-1, crystal size
0.1 × 0.3 × 0.6 mm3, 8573 reflections collected (5880 inde-
pendent, Rint ) 0.0208), 370 parameters, R1 [I > 2σ(I)] ) 0.0353,
wR2 [all data] ) 0.0835, largest diff peak and hole 0.603 and
Derived from 1-Aza-2-phosphaallyl Ligands
4
8.3 Hz, C15,19), 131.2 (d, JC,P ) 2.3 Hz, C17), 128.8 (s, C22,24),
127.8 (d, 3JC,P ) 11.3 Hz, C16,18), 127.5 (s, C3,6), 127.0 (d, 3JC,P
)
1.5 Hz, C1,8), 126.4 (d, 4JC,P ) 2.3 Hz, C2,7), 123.3 (d, 3JC,P ) 18.9
-0.335 e Å-3
.
1
Hz, C21,25), 119.5 (s, C4,5), 117.3 (s, C23), 49.8 ppm (d, JC,P
)
Computational Details. Rhodium and phosphorus were treated
with a Stuttgart-Dresden pseudopotential in combination with their
adapted basis set.25 In all cases, the basis set has been augmented
by a set of polarization functions (f for Rh and d for P).26 Carbon,
nitrogen, and hydrogen atoms have been described with a 6-31G-
(d,p) double-ú basis set.27 Calculations were carried out at the DFT
level of theory using the hybrid functional B3PW91.28 Geometry
optimizations were carried out without any symmetry restrictions;
the nature of the extrema (minimum) was verified with analytical
frequency calculations. All these computations have been performed
with the Gaussian 9829 suite of programs. The electronic density
has been analyzed using the natural bonding analysis (NBO)
technique.21
75.5 Hz, C9). MS (EI, 70 eV) m/z (%): 441 [M]+, 276 [M - Flu]+,
165 [Flu]+. Mp: 243 °C. Anal. Calcd for C31H24NP: C, 84.35; H,
5.44; N, 3.17. Found: C, 83.80; H, 5.30; N, 3.10.
Preparation of 3 from 2. To a solution of 2 (95.7 mg, 0.216
mmol) in THF (6 mL) was added at -78 °C 0.144 mL of a 1.6 M
solution of nBuLi in hexanes, and the solution was stirred 30 min
at room temperature. The reaction medium was cooled to 0 °C,
and a solution of [Rh(µ-Cl)(nbd)]2 (50 mg, 0.108 mmol) in THF
(3 mL) was added. After warming to room temperature and
subsequent stirring for 2 h, the solvent was eliminated under
vacuum. The yellow residue was extracted with CH2Cl2 (10 mL)
and evaporated to dryness, yielding a yellow solid (123 mg, 90%).
Crystals suitable for X-ray crystallography were obtained from a
CHCl3 solution at -25 °C. 31P{1H} NMR (202.5 MHz, CDCl3,
243 K): δ 24.1 ppm (d, 2JP,Rh ) 16.2 Hz). 1H NMR (500.3 MHz,
Acknowledgment. We are grateful to the CNRS, UPS, and
French Ministry of Research and New Technologies (ACI
JC4091) for financial support of this work. CalMip (CNRS,
Toulouse, France) is acknowledged for calculation facilities.
3
CDCl3, 243 K): δ 7.98 (d, JH,H ) 7.6 Hz, 2H, H4,5), 7.85 (dd,
3
3
3JH,P ) 11.8 Hz, JH,H ) 7.5 Hz, 4H, H15,19), 7.63 (t, JH,H ) 7.0
Hz, 2H, H17), 7.50 (m, 4H, H16,18), 7.15-7.08 (m, 6H, H2,3,6,7,22,24),
Supporting Information Available: Cartesian coordinates for
the optimized complexes 3 and 3′, atom numbering for the NMR
assignments, and crystallographic data for derivatives 2 and 3
including cif files. This material is available free of charge via the
Internet at http://pubs.acs.org.
3
3
6.88 (d, JH,H ) 7.9 Hz, 2H, H1,8), 6.84 (t, JH,H ) 7.3 Hz, 1H,
3
H23), 6.66 (d, JH,H ) 7.8 Hz, 2H, H21,25), 4.08 (br s, 2H, H26,27),
2
3.48 (br s, 2H, H30,31), 1.47 (br s, 2H, H28,29), 1.07 (d, JH,H ) 8.6
Hz, 1H, H32A), 0.83 ppm (d, JH,H ) 8.6 Hz, 1H, H32B). 13C{1H}
3
NMR (125.8 MHz, CDCl3, 243 K): δ 149.5 (s, C20), 141.4 (d,
2JC,P ) 10.1 Hz, C10,13), 134.1 (d, 2JC,P ) 11.31 Hz, C11,12), 132.60
(s, C17), 132.0 (d, 2JC,P ) 10.7 Hz, C15,19), 131.25 (d, 1JC,P ) 74.8
Hz, C14), 129.1 (d, 3JC,P ) 11.7 Hz, C16,18), 128.9 (s, C22,24), 123.9
(s, C2,7), 121.8 (d, 3JC,P ) 14.0 Hz, C21,25), 121.4 (s, C1,8), 120.4 (s,
OM0605377
(22) SADABS, Program for data correction, version 2.10; Bruker-AXS,
2003.
(23) Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467-473.
(24) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure
Refinement; University of Go¨ttingen, 1997.
(25) (a) Andrae, D.; Haeussermann, U.; Dolg, M.; Stoll, H.; Preuss, H.
Theor. Chim. Acta 1990, 77, 123-141. (b) Bergner, A.; Dolg, M.; Kuechle,
W.; Stoll, H.; Preuss, H. Mol. Phys. 1993, 80, 1431-1441.
(26) Ehlers, A. W.; Bo¨hme, M.; Dapprich, S.; Gobbi, A.; Ho¨llwarth,
A.; Jonas, V.; Ko¨hler, K. F.; Stegmann, R.; Veldkamp, A.; Frenking, G.
Chem. Phys. Lett. 1993, 208, 111-114.
C
3,6), 119.6 (s, C4,5) 119.5 (s, C23), 61.9 (br s, C32), 58.2 (d, 3JC,P
)
7.8 Hz, C26,27), 51.7 (d, 2JC,P ) 9.6 Hz, C28,29), 50.3 (s, C30,31), 33.90
ppm (dd, 1JC,P ) 109.3, 1JC,Rh ) 10.5 Hz, C9). MS (DCI/CH4) m/z
(%): 636 [MH]+ (100), 635 [M]+ (75), 544 [M - COD]+ (4).
Mp: 276 °C. Anal. Calcd for C38H31NPRh: C, 71.82; H, 4.90; N,
2.20. Found: C, 71.36; H, 4.83; N, 2.17.
X-ray Crystal Structures of 2 and 3. Data for all structures
were collected at 133(2) K using an oil-coated shock-cooled crystal
on a Bruker-AXS CCD 1000 diffractometer (λ ) 0.71073 Å).
Semiempirical absorption corrections were employed.22 The struc-
tures were solved by direct methods (SHELXS-97)23 and refined
using the least-squares method on F2.24 Crystallographic data
(excluding structure factors) have been deposited with the Cam-
bridge Crystallographic Data Centre as supplementary publica-
tion nos. CCDC-297701 (2) and 297702 (3). These data can be
obtained free of charge via www.ccdc.cam.uk/conts/retrieving.html
(or from the CCDC, 12 Union Road, Cambridge CB2 1EZ, UK;
fax: (+44) 1223-336-033; or deposit@ccdc.cam.ac.uk). Crystal data
for 2: C31H24NP, M ) 441.48, monoclinic, space group P21/n, a
) 9.4833(9) Å, b ) 12.6243(13) Å, c ) 19.2691(19) Å, â )
(27) Hariharan, P. C.; Pople, J. A. Theor. Chim. Acta 1973, 28, 213-222.
(28) (a) Becke, A. D. J. Chem. Phys. 1993, 98, 5648-5652. (b) Burke,
K.; Perdew, J. P.; Yang, W. Electronic Density Functional Theory: Recent
Progress and New Directions, Dobson, J. F., Vignale, G. Das, M. P., Eds.;
1998.
(29) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb,
M. A.; Cheeseman, J. R.; Zakrzewski, V. G.; Montgomery, J. A.; Stratman,
R. E.; Burant, J. C.; Dapprich, S.; Millam, J. M.; Daniels, A. D.; Kudin, K.
N.; Strain, M. C.; Farkas, O.; Tomasi, J.; Barone, V.; Cossi, M.; Cammi,
R.; Mennucci, B.; Pomelli, C.; Adamo, C.; Clifford, S.; Ochterski, J.;
Petersson, G. A.; Ayala, P. Y.; Cui, Q.; Morokuma, K.; Malick, D. K.;
Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Cioslowswi, J.; Ortiz,
J. V.; Baboul, A. G.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.;
Komaromi, I.; Gomperts, R.; Martin, R.; Fox, D. J.; Keith, T.; Al-Laham,
M. A.; Peng, C. Y.; Nanayakkara, A.; Gonzalez, C.; Challacombe, M.; Gill,
P. M. W.; Jonhson, B.; Chen, W.; Wong, M. W.; Andres, J. L.; Head-
Gordon, M.; Replogle, E. S.; Pople, J. A. Gaussian 98, ReVision A.11;
Gaussian, Inc.: Pittsburgh, PA, 1998.
98.991(2)°, V ) 2278.6(4) Å3, Z ) 4, µ(Mo KR) ) 0.141 mm-1
,