Reductive elimination of α-phosphinozirconocene iminoacyl complexes: First evidence of neutral η1-imine zirconocene. Synthesis of bi- or tricyclic β-phosphino imines

Article abstract of DOI:10.1021/ja990502g

Phosphinozirconocene complexes react with isocyanides to give unprecedented bi- or tricyclic β-phosphino imines through three successive and controlled steps. Spectroscopic and chemical evidence for the formation of the first neutral η¹-imine z

Full text of DOI:10.1021/ja990502g

11086
J. Am. Chem. Soc. 1999, 121, 11086-11092
Reductive Elimination of R-Phosphinozirconocene Iminoacyl
Complexes: First Evidence of Neutral η1-Imine Zirconocene.
Synthesis of Bi- or Tricyclic â-Phosphino Imines
Victorio Cadierno,† Maria Zablocka,† Bruno Donnadieu,† Alain Igau,†
Jean-Pierre Majoral,*,† and Aleksandra Skowronska*,‡
Contribution from Laboratoire de Chimie de Coordination du CNRS, 205 route de Narbonne,
31077 Toulouse Cedex 4, France, and Centre of Molecular and Macromolecular Studies of Lodz,
Polish Academy of Sciences, Sienkiewicza 112 90-362 Lodz, Poland
ReceiVed February 17, 1999
Abstract: Phosphinozirconocene complexes react with isocyanides to give unprecedented bi- or tricyclic
â-phosphino imines through three successive and controlled steps. Spectroscopic and chemical evidence for
the formation of the first neutral η1-imine zirconocene complexes in the reductive elimination reaction sequence
is presented.
Introduction
for example, to aldehydes2a,5a or nitriles.7 We report herein a
powerful one-pot synthesis of unprecedented bi- or tricyclic
â-phosphino imines from R-phosphino cyclic organozir-
conocenes and isocyanides through a process involving three
successive and controlled steps: a regioselective Zr-C isocya-
nide insertion reaction, followed by a carbon-carbon coupling
reaction to form a neutral η1-imine zirconocene complex,8
and subsequent reductive elimination of zirconocene fragment
“Cp2Zr”. The synthesis and X-ray analysis of the first â-amino
indenophosphine are also described.
Reductive elimination reactions are among the most valuable
processes to form carbon-carbon bonds in organic synthesis.1
More specifically, the readily available metallacycles incorporat-
ing group 4 elements2 would be useful tools for ring formation
through a carbon-carbon coupling. However, intramolecular
coupling reactions of group 4 iminoacyl complexes, yielding
the corresponding free imines, are rather rare and mainly involve
titanium complexes.3,4 The mechanism of these reactions still
remains unclear, although a concerted reductive elimination step
that initially leads to an η1-imine intermediate complex of the
type I has already been postulated.3a However, none of the
previous reports described isolation and characterization of η1-
imine zirconocene complexes. Addition of isocyanides on
organozirconocenes is known to give the corresponding imi-
noacyl complexes after insertion into a zirconium-carbon
bond.5,6 These compounds have been conveniently converted,
Results and Discussion
* Corresponding author. E-mail: majoral@lcc-toul.fr. Tel.: (33) 05 61
33 31 23. Fax: (33) 05 61 55 30 03.
Treatment of a toluene solution of the R-phosphinozircon-
aindene 19 with the isocyanide Me3SiCH2NC (2a) at room
temperature for 15 min leads to the η2-iminoacyl complex 3a
(Scheme 1), as clearly shown by 13C NMR.10 The signal at 200.7
ppm is typical for a ZrsCdN unit.11 The disappearance of the
characteristic deshielded chemical shift of the Zr-C(sp2) aryl
carbon of the indene moiety in 1 at 184.9 ppm to give a new
signal resonance in 3a at 121.5 ppm, classical for an aryl-C(sp2)
carbon atom, demonstrates the regioselective insertion of 2a
into the intracyclic Zr-C(sp2) bond in 1 at the opposite side of
the phosphino group. An X-ray crystallography study was
† Laboratoire de Chimie de Coordination du CNRS.
‡ Polish Academy of Sciences.
(1) Davies, S. Organotransition Metal Chemistry: Applications to
Organic Synthesis; Pergamon Press: Oxford, 1982. The Chemistry of the
Metal-Carbon Bond; Hartley, F. R., Patai, S., Eds.; J. Wiley & Sons:
Chichester, 1985; Vol. 3 (Carbon-Carbon Bond Formation Using Orga-
nometallic Compounds).
(2) (a) Buchwald, S. L.; Nielsen, R. B. Chem. ReV. 1988, 88, 1047. (b)
Rajan Babu, T. V.; Nugent, W. A.; Taber, D. F.; Fagan, P. J. J. Am. Chem.
Soc. 1988, 111, 7128. (c) Knight, K. S.; Waymouth, R. M. J. Am. Chem.
Soc. 1991, 113, 6268 and references therein.
(3) (a) Campora, J.; Buchwald, S. L. Organometallics 1995, 14, 2039.
(b) Scott, C. B.; Grossman, R. B.; Buchwald, S. L. J. Am. Chem. Soc. 1993,
115, 4912. (c) Durfee, L. D.; Hill, J. E.; Fanwick, P. E.; Rothwell, I. P.
Organometallics 1990, 9, 75. (d) Durfee, L. D.; Hill, J. E.; Fanwick, P. E.;
Rothwell, I. P. J. Am. Chem. Soc. 1987, 109, 4720.
(4) (a) Probert, G. D.; Whitby, R. J.; Coote, S. J. Tetrahedron Lett. 1995,
36, 4113. (b) Davis, J. M.; Whitby, R. J.; Jaxa-Chamiec, A. Tetrahedron
Lett. 1994, 35, 1445. A formal reductive elimination/ring contraction reaction
has been described from treatment of a 1-zircona-2-azacyclopentene with
tBuNC and MeOH to form a C-N bond. Davis, J. M.; Whitby, R. J.; Jaxa-
Chamiec, A. J. Chem. Soc., Chem. Commun. 1991, 1743.
(6) Only two examples showed an insertion at Zr-C(sp2); see ref 2a.
(7) Buchwald, S. L.; LaMaire, S. Tetrahedron Lett. 1987, 28, 295.
(8) For cationic η1-imine zirconocene complexes, see: Guran, A. S.;
Jordan, R. F. J. Org. Chem. 1993, 58, 5595.
(9) Miquel, Y.; Igau, A.; Donnadieu, B.; Majoral, J.-P.; Dupuis, L.; Pirio,
N.; Meunier, P. Chem. Commun. 1997, 279.
1
(10) 13C NMR assignments were deduced by inverse gradient δ H-δ
13C {13C,31P} HMQC and 31P-1H INEPT NMR experiments.
(11) For characteristic signals of iminoacyl groups, see: Carmona, E.;
Palma, P.; Paneque, M.; Poveda, M. L. Organometallics 1990, 9, 583.
Bochmann, M.; Wilson, L. M.; Hursthouse, M. B.; Short, R. Organome-
tallics 1987, 6, 2556. Durfee, L. D.; Rothwell, I. P. Chem. ReV. 1988, 88,
1059.
(5) (a) Negishi, E.-I.; Swanson, D. R.; Miller, S. Tetrahedron Lett. 1988,
29, 1631. (b) Cuny, G. D.; Gutierrez, A.; Buchwald, S. L. Organometallics
1991, 10, 537. (c) Aoyagi, K.; Kasai, K.; Kondakov, D. Y.; Hara, R.; Suzuki,
N.; Takahashi, T. Inorg. Chim. Acta 1994, 220, 319 and references therein.
10.1021/ja990502g CCC: $18.00 © 1999 American Chemical Society
Published on Web 11/13/1999

Neutral η1-Imine Zirconocene
J. Am. Chem. Soc., Vol. 121, No. 48, 1999 11087
a vinyl C(sp2) in indene derivatives. Therefore, the NMR data
and the chemical reactivity of 4a are not consistent with η2-
imine zirconocene complex structure II. It is important to note
that molecular modeling (MM2 parameters, CAChe system)
shows the impossibility for compound 4a to adopt the η2-π-
bonded-imine zirconocene structure A, with the phosphorus
atom of the phosphino group coordinated on the metal fragment.
On the basis of the chemistry described with zirconocene
complexes, two other structures may be envisaged for 4a. The
first one is the s-trans diene complex B, investigated by Erker
et al.,14 and the second one is the η1-imine-η3-allyl form C,
which could be proposed by analogy with the postulated
intermediate in carbonylation of zirconacyclopentenes.15 In the
view of the NMR data, contributions of these structures cannot
be totally ruled out, even if it seems unreasonable to postulate
form B in our case as a possible stable complex, as the isolated
product 4a possesses in its skeleton two efficient ligands, a
phosphine and an imine, with good geometry for both to interact
with the zirconocene metal fragment. Indeed, we tentatively
propose for 4a an η1-imine zirconocene complex structure
stabilized intramolecularly by the phosphino group linked to
the indene moiety. This assumption came from the additional
following points: (i) 13C NMR data are more consistent with
this latter structure. Indeed, the 13C NMR chemical shift of the
imino carbon atom in 4a is between that of the C-N carbon
atom signal in η2-imine complex structure II and that of free
imine compounds. (ii) Previous mechanistic studies3a,13 have
shown that the initial intermediate in the reductive elimination
process yielding free imines is an η1-imine complex. (iii) The
green color observed appears to be characteristic for zirconocene
species stabilized by two neutral two-electron-donating ligands.16
(iv) Experiments have demonstrated that Cp2ZrII species formed
in the reductive elimination of R-alkynyl-substituted zircona-
cyclopentenes were trapped as alkyne complexes stabilized by
PMe3.17 Formation of 4a may result from a carbon-carbon
coupling reaction between the iminoacyl unit and the intracyclic
vinyl group of the indene moiety; the η2-imine zirconocene
complex should not be ruled out, as it may be involved in the
previous step of the formation of 4a, but in the presence of the
phosphine coordinating group the η1-imine form is thermody-
namically favored over the η2-imino form. The same reaction
performed with 1 and the isocyanide 2b gave the green η1-
imine zirconocene complex 4b (Scheme 1); transient formation
of 3b was not detected during the course of the reaction. The
same NMR characteristic features described for 4a were
observed for 4b. In marked contrast to 4a, 4b slowly rearranges
to give the first â-phosphino indenoimine, 5b (Scheme 2). This
rearrangement can be monitored by 31P NMR, which shows the
disappearance of the signal due to 4b (δ ) 8.7 ppm) on behalf
of a signal at -23.9 ppm, strongly indicative of the presence
of a free phosphino group in 5b. The 13C NMR spectrum of 5b
Figure 1. X-ray crystal structure of 3a (CAMERON drawing with
thermal ellipsoids at 50% probability; Cp groups were omitted for
clarity). Selected bond lengths (Å) and angles (deg): Zr-C(1) 2.368-
(8), Zr-C(9) 2.163(8), Zr-N 2.229(7), N-C(9) 1.278(11), P-C(1)
1.841(9), N-Zr-C(1) 107.5(3), N-Zr-C(9) 33.8(3), Zr-N-C(9)
70.3(5), Zr-C(9)-N 76.0(5).
Scheme 1. Synthesis of η1-Imino Complexes 4a and 4b (a,
R ) CH2SiMe3; b, R ) 2,6-Me2C6H3)
undertaken to complete the characterization of 3a (Figure 1,
Table 1). The orange η2-iminoacyl complex 3a smoothly
rearranges at room temperature after 7 days in benzene to give
a stable green complex, 4a, formed in quantitative yield, as
monitored by 31P NMR by the disappearance of the signal due
to 3a (δ ) 2.0 ppm) on behalf of a new signal at 16.2 ppm
(Scheme 1). Iminoacyl group 4 complexes are known to
rearrange to form stable zirconocene η2-imine complexes.12
These derivatives, better described as metallaaziridines, undergo
coupling reactions with unsaturated organic compounds to
cleanly form metallacyclic compounds.13 In marked contrast to
the reactivity observed for metallaaziridine complexes, 4a does
not give any reaction with acetylenic systems or nitriles.
Moreover, 13C NMR experiments10 showed the chemical shift
corresponding to the carbon atom of the C-N skeleton at 118.9
(JCP ) 25.1 Hz) ppm, which is far deshielded compare to the
signals observed for metallaaziridines in the range of 40-60
ppm (Table 2).12,13 The carbon atom directly bonded to the
phosphine moiety has shifted from 190.8 (JCP ) 95.5 Hz) ppm
in 3a, typical for a C(sp2) in R position of a zirconocene
fragment, to 110.4 (JCP ) 42.2 Hz) ppm in 4a, in accord with
(12) Davis, J. M.; Whitby, R. J.; Jaxa-Chamiec, A. Tetrahedron Lett.
1992, 33, 5655.
(14) See, for example: Erker, G.; Berlekamp, M.; Lopez, L.; Grehl, M.;
Scho¨necker, B.; Krieg, R. Synthesis 1994, 212.
(15) (a) Mory, M.; Uesaka, N.; Shibasaki, M. J. Org. Chem. 1992, 57,
3519. (b) Barluenga, J.; Sanz, R.; Fanana`s, F. J. Chem. Eur. J. 1997, 3,
1324.
(16) Gell, K. I.; Schwartz, J. J. Am. Chem. Soc. 1981, 103, 2687.
(17) Liu, Y.; Sun, W.-H.; Nakajima, K.; Takahashi, T. Chem. Commun.
1998, 1133.
(13) (a) Coles, N.; Harris, M. C. J.; Whitby, R. J.; Blagg, J. Organo-
metallics 1994, 13, 190. (b) Broene R. D.; Buchwald S. L. Science 1993,
261, 1696 and references therein. (c) Coles, N.; Whitby, R. J.; Blagg, J.
Synlett 1992, 143. (d) Buchwald, S. L.; Watson, B. T.; Wanamaker, M.
W.; Dewan, J. C. J. Am. Chem. Soc. 1989, 111, 4486. (e) Davis, J. M.;
Whitby, R. J.; Jaxa-Chamiec, A. Synlett 1994, 111.

11088 J. Am. Chem. Soc., Vol. 121, No. 48, 1999
Cadierno et al.
Table 1. Crystal Data and Data Collection Parameters for Compounds 3a, 6b, and 8b
3a
6b
8b
asymmetric unit
molecular weight
C35H36NPSiZr
620.96
1.36
4.69
638.41
monoclinic
P21
11.579(2)
26.073(4)
10.051(2)
89.943(2)
3029.9(3)
4
C29H24NPS
449.55
1.28
2.17
944.93
monoclinic
P21/n
9.162(2)
24.451(3)
11.237(2)
112.55(2)
2324.9(3)
4
C29H26NPS
451.57
1.30
F
calcd (g cm-3
)
µ (cm-1
F000
)
2.18
476.46
triclinic
P1h
9.959(2)
10.942(2)
11.242(2)
102.16(2)
1156.2(3)
2
crystal system
space group
a (Å)
b (Å)
c (Å)
â (deg)
V (Å3)
Z
crystal size
crystal shape
crystal color
no. of measured reflections
no. of independent reflections
merging R value
refinement on
hydrogen atoms
Ra
0.5 × 0.2 × 0.1
0.6 × 0.4 × 0.4
0.2 × 0.1 × 0.1
plate
parallelepiped
parallelepiped
light orange
19 214
8918
0.050
Fobs
calculated and not refined
0.045
0.051
0.015(5)
2.90; -0.91
1.06
Chebyshev
1.79, -0.234, 1.07
none
light red
14 311
3648
0.035
orange yellow
6809
3484
0.049
Fobs
Fobs
calculated and not refined
0.029
0.029
calculated and not refined
0.050
0.056
b
Rw
Flack parameterc
-
-
∆Fmax; ∆Fmin (e Å3)
GOF (S)d
1.22; -0.86
0.41; -0.50
1.04
1.01
weighting schemee
parameters used
Chebyshev
1.47, -1.58, 1.15, -0.664, 0.196
none
2999
294
Chebyshev
1.37, -1.26, 0.751, -0.562
none
2507
294
absorbance correction
no. of reflections used [I > 2σ(I)]
no. of parameters used
8267
704
a R ) ∑(||Fo| - |Fc||)/∑|Fo|. b Rw ) [∑w(||Fo| - |Fc||)2/∑w(|Fo|)2]1/2
.
c Reference 25. d Goodness of fit ) [∑(|Fo - Fc|)2/(Nobs - Nparameters)]1/2
.
e W ) [weight][1 - ∆F/6σF)2]2 where weight is calculated from the following expression: weight ) 1/∑(r ) 1, n)ArTx(X), where Ar are the coef-
ficients for the Chebyshev polyniomal Tr(X) with X ) Fc/Fc(max). See: Carruthers, J. R.; Watkin, D. J. Acta Crystallogr. 1979, A35, 698-699.
exhibits a doublet at 168.7 (JCP ) 16.6 Hz) ppm, characteristic
for the cyclic imino carbon,10 whereas the chemical shift of the
sp2 carbon atom of the indene moiety directly bonded to the
phosphino group shifted from 106.8 (JCP ) 37 Hz) to 144.1
(JCP ) 14.6 Hz) ppm. Therefore, a quite similar and significant
deshielding effect is detected on both the imino carbon (∆δ )
32.5 ppm) and the C(sp2) atom bonded to phosphorus (∆δ )
37.3 ppm) when moving from the proposed η1-imino zir-
conocene complex 4b to the free â-phosphino indenoimine 5b.
Mass spectrometry (DCI m/z 417 [M+]) supports the removal
of the metal fragment in 5b. The structure of 5b was fully
corroborated by X-ray diffraction studies conducted on the
corresponding sulfide compound 6b (Figure 2, Table 1).
Interestingly, addition of HCl‚OEt2 (2 equiv) on a toluene
solution of 4a or 4b gave the unexpected â-aminophosphine,
7a or 7b, respectively (Scheme 2). The structure of the sulfide
adduct of 7b, i.e., 8b, was confirmed by X-ray analysis (Figure
3, Table 1). It has long been demonstrated in late-transition-
metal chemistry that imine coordination-type complexes I and
II may exist as an equilibrium.18 In group 4 metallocene
chemistry, the complexes of type I have never been isolated;
they rearrange to the more stable σ-bonded η2-imine zirconocene
complexes II. Then, it is reasonnable to postulate that, in the
presence of HCl, it is the metallaaziridine forms 9a,b which
react to give derivatives 10a,b, which in turn rearrange to the
final products 7a,b (Scheme 2).19,20
this sequence of reactions with isocyanides on another type of
cyclic zirconaphosphine complex, i.e., the tricyclic system 11.21
Insertion of isocyanide 2a occurs chemoselectively on the
Zr-C(sp3) bond, leading to the stable iminoacyl complex 12a
(Scheme 3). 13C NMR strongly supports the assigned structure;
in particular, the signal of the quaternary aromatic carbon
directly linked to zirconium is, as expected, deshielded at δ )
168.6 ppm, demonstrating that the insertion reaction of the
isocyanide reagent occurs now at the same side of the phosphine
moiety. Chemical evidence of the formation of 12a can be found
when it is reacted with HCl‚OEt2: the substituted phospholane
13a (Scheme 3) arising from the selective cleavage of the Zr-
C(sp2) bond is quantitatively isolated and fully characterized.22
As in the case of the reaction of 1 with 2b, 11 reacts with
the isocyanide 2b to give the stable tetracyclic zirconocene imine
complex 14b. Once again, the NMR data and the chemical
reactivity (no reaction of 14b with acetylenic compounds and
nitriles) are not consistent with an η2-imine zirconocene complex
structure, II, for 14b but are in agreement with an η1-imine-
type coordination, I. The complex 14b slowly rearranges into
the new tricyclic â-phosphino imine 15b (Scheme 3) upon
stirring at room temperature overnight. Compound 15b presents
characteristic NMR data for such a species. Mass spectrometry
(19) If the participation of the η2-imine zirconocene structure is reason-
able to explain the synthesis of 7a,b, the formation of this intermediate in
the preparation of 5b is more questionable, as it has been demonstrated
that it is possible to displace a titanium metal center from its unreduced
imine group by addition of external ligands, see ref 3c,d.
(20) It is of interest to note that addition of HCl on 5b does not give 7b.
(21) Zablocka, M.; Ce´nac, N.; Igau, A.; Donnadieu, B.; Majoral, J.-P.;
Skowronska, A.; Meunier, P. Organometallics 1996, 15, 5436.
To generalize the reductive elimination reaction process for
the synthesis of new classes of P,N ligands, we have extended
(18) Calligaris, M.; Randaccio, L. In ComprehensiVe Coordination
Chemistry; Wilkinson, G., Gillard, R. D., McCleverty, J. A., Eds.; Pergamon
Press: Oxford, England, 1987; Chapters 20.1 and 21.2 and references
therein.
(22) NMR data of 13a are in full agreement with those of similar
compounds, see: Zablocka, M.; Igau, A.; Cenac, N.; Donnadieu, B.; Dahan,
F.; Majoral, J.-P.; Pietrusiewicz, M. K. J. Am. Chem. Soc. 1995, 117, 8083.

Neutral η1-Imine Zirconocene
Table 2.
13C (ZrCN)a Spectroscopic Data of η2-Imine Zirconocene Complexes Cp2Zr(η2-CRR′dNR′′)(phosphine)
J. Am. Chem. Soc., Vol. 121, No. 48, 1999 11089
δ
a NMR spectra taken in benzene-d6. Chemical shifts in ppm, coupling constants (between parentheses) in Hz. Fur ) furyl, Thio ) thiophene.
Scheme 2. Reactivity of η1-Imino Complexes 4a and 4b (a,
R ) CH2SiMe3; b, R ) 2,6-Me2C6H3)
All these observations are in agreement with our proposal to
reject also structures B and C for compounds 4a,b and to suggest
an η1-imine zirconocene complex structure for 4a,b and 14b,c.
In conclusion, we presented a number of arguments allowing
us to propose that the mechanism of the reductive elimination
reaction involving phosphorus-zirconium heterocyclic reagents
and isocyanides and leading to new elaborated P,N ligands
follows three steps: (i) insertion reaction of the isocyanide
reagent to give the corresponding iminoacyl complex, (ii)
carbon-carbon coupling reaction to form an η1-imine zir-
conocene complex intramolecularly stabilized by a phosphino
group, and (iii) elimination of the metal fragment “Cp2Zr” to
give the corresponding â-phosphino imine derivative. Ligand-
induced reductive elimination in titanium chemistry has been
demonstrated;3c,d thus, it is reasonable to postulate here the key
role played by the phosphino group located in the close
environment of the metal in the course of the metal center
displacement step (iii). Each intermediate involved in the
reaction sequence has been fully characterized by X-ray analysis
and/or NMR spectroscopy analysis. This reductive elimination
process extends the scope of the zirconocene-induced coupling
reactions, allowing us to synthesize a variety of new bicyclic
or tricyclic phosphorus-nitrogen-containing ligands, and opens
new strategies for the preparation of chiral ligands and catalysts
for a large number of reactions.23
(DCI, m/z 370 [M+ + 1]) is in agreeement with the proposed
structure. An analogous reaction performed with 11 and the
isocyanide 2c affords the tricyclic phosphinoimine 15c. In this
case, the formation of the η1-imine derivative 14c was detected
only by 31P NMR (14c, δ ) 1.8; 15c, δ ) 12.6 ppm).
Structures of types B and C can be rejected for compounds
14b,c (no carbon-carbon double bond acting as ligand), which
are formed through the same type of mechanism involved for
the preparation of 4a,b and which present NMR data similar to
those detected for 4a,b. Moreover, a careful examination of the
13C NMR data for the imino group >CdNs for compounds
4b and 5b on one hand and 14b and 15b on the other hand
shows the same variation of chemical shifts when moving from
4b to 5b and from 14b to 15b, and close chemical shifts were
observed for 4b and 14b on one hand and 5b and 15b on the
other hand (4b, δ CdN 136.2 (JCP ) 27.5 Hz); 5b, δ CdN
168.7 (JCP ) 16.6 Hz); 14b, δ CdN 125.0 (JCP ) 17.0 Hz);
15b, δ CdN 175.0 (JCP ) 14.4 Hz)).
Experimental Section
General Procedure, Methods, and Materials. All manipulations
were performed under an argon atmosphere, either on a high-vacuum
line using standard Schlenk techniques or in a Braun MB 200-G drybox.
(23) Steinhagen, H.; Reggelin, M.; Helmchen, G. Angew. Chem., Int.
Ed. Engl. 1997, 36, 2108. Schnider, P.; Koch, G.; Pre´toˆt, R.; Wang, G.;
Bohnen, F. M.; Kru¨ger, C.; Pfaltz, A. Chem. Eur. J. 1997, 3, 887. Lightfoot,
A.; Schnider, P.; Pfaltz, A. Angew. Chem., Int. Ed. Engl. 1998, 37, 2897.

11090 J. Am. Chem. Soc., Vol. 121, No. 48, 1999
Cadierno et al.
Figure 2. X-ray crystal structure of 6b (CAMERON drawing with thermal ellipsoids at 50% probability). Selected bond lengths (Å) and angles
(deg): N-C(9) 1.274(2), P-C(1) 1.8109(16), C(1)-C(9) 1.500(2), C(1)-C(2) 1.342(2), C(9)-N-C(10) 120.24(13), N-C(9)-C(1) 124.08(14),
C(1)-C(9)-C(8) 105.04(13).
Scheme 3. Synthesis of â-Phosphino Imines 15b and 15c
spectrometers. The 13C NMR assignments were confirmed by proton-
decoupled and/or selective heteronuclear-decoupled spectra. Positive
chemical schifts are given downfield relative to Me4Si (1H, 13C) or
H3PO4 (31P) references, respectively. Mass spectra were obtained on a
Nermag R10-10H and performed by the analytical service of the
Laboratoire de Chimie de Coordination (LCC) of the CNRS.
Experimental Procedure. 3a. To a solution of 1 (0.189 g, 0.372
mmol) in toluene (5 mL) was added trimethylsilylmethyl isocyanide
(2a) (0.052 mL, 0.372 mmol) at room temperature. The mixture was
stirred for 15 min and then evaporated to dryness. The solid residue
was extracted with a mixture of THF/pentane (5 mL/40 mL) and
filtered. The volatiles were removed from the solution, and the resulting
Figure 3. X-ray crystal structure of 8b (CAMERON drawing with
solid was washed with pentane (5 mL) to give 3a as a yellow solid in
thermal ellipsoids at 50% probability). Selected bond lengths (Å) and
1
76% yield (0.176 g). 31P{1H} NMR (C6D6): δ 2.0 (s) ppm. H NMR
angles (deg): N-C(9) 1.358(4), P-C(1) 1.764(3), C(1)-C(9) 1.374-
(C6D6): δ -0.01 (s, 9H, SiMe3), 3.52 (s, 2H, CH2), 5.68 (s, 10H, Cp),
(4), C(1)-C(2) 1.505(4), C(9)-N-C(10) 128.5(3), N-C(9)-C(1)
6.98-7.37 (m, 11H, CHarom), 7.79-7.86 (m, 3H, CHarom), 8.09 (d, 1H,
125.1(3), C(1)-C(9)-C(8) 108.7(3).
JHP ) 22.5 Hz, PCCH) ppm. 13C{1H} NMR (C6D6): δ -1.2 (s, SiMe3),
Solvents were freshly distilled from dark purple solutions of sodium/
benzophenone ketyl (THF, diethyl ether), lithium aluminum hydride
(pentane), sodium (toluene), or CaH2 (CH2Cl2). Deuterated NMR
solvents were treated with LiAlH4 (C6D6) and CaH2 (CDCl3), distilled,
and stored under argon. Complexes 19 and 1121 were prepared according
to literature procedure.
Trimethylsilylmethyl isocyanide, 2,6-dimethylphenyl isocyanide, and
tert-butyl isocyanide were used as received from Aldrich Chemical Co.
Nuclear magnetic resonance (NMR) spectra were recorded at 25 °C
on Bruker MSL 400, WM-250, AC-200, and AC-80 Fourier transform
49.4 (s, CH2), 108.1 (d, JCP ) 2.4 Hz, Cp), 121.5 (s, ZrCC), 123.9,
126.4 and 128.4 (s, CHarom), 129.0 (d, JCP ) 6.2 Hz, o-PPh2 or m-PPh2),
132.9 and 134.9 (s, CHarom and p-PPh2), 135.1 (d, JCP ) 18.5 Hz, o-PPh2
or m-PPh2), 142.4 (d, 1JCP ) 27.2 Hz, i-PPh2), 149.6 (d, 3JCP ) 9.6 Hz,
2
1
ZrCCC), 151.5 (d, JCP ) 8.7 Hz, ZrCCH), 190.8 (d, JCP ) 95.5 Hz,
3
ZrCP), 200.7 (d, JCP ) 5.7 Hz, ZrCN) ppm. MS (FAB): m/z 619
[M+]. Anal. Calcd for C35H36PNSiZr: C, 67.69; H, 5.84; N, 2.25.
Found: C, 67.51; H, 5.77; N, 2.27.
4a. In an NMR tube, complex 3a (0.050 g, 0.080 mmol) was
dissolved in C6D6 (1 mL). After 7 days at room temperature, complex

Neutral η1-Imine Zirconocene
J. Am. Chem. Soc., Vol. 121, No. 48, 1999 11091
4a was formed in almost quantitative yield, as monitored by 31P{1H}
7.58 (m, 14H, CHarom) ppm. 13C{1H} NMR (C6D6): δ -2.4 (s, SiMe3),
37.8 (d, JCP ) 12.0 Hz, CH2CP), 39.3 (d, JCP ) 3.8 Hz, CH2SiMe3),
102.2 (d, JCP ) 8.2 Hz, CdCP), 119.2, 124.8, 126.6 and 126.7 (s,
CHarom), 128.5 (s, p-PPh2), 129.0 (d, JCP ) 6.0 Hz, o-PPh2 or m-PPh2),
133.7 (d, JCP ) 18.4 Hz, o-PPh2 or m-PPh2), 140.2 (d, JCP ) 8.7 Hz,
CdCP), 146.8 (s, CCH2), 158.2 (d, JCP ) 25.6 Hz, CCdCP) ppm.
i-PPh2 not observed. MS (DCI): m/z 402 [M+ + 1]. Anal. Calcd for
C25H28PNSiP: C, 74.77; H, 7.02; N, 3.48. Found: C, 74.68; H, 6.91;
N, 3.52.
1
NMR spectroscopy. 31P{1H} NMR (C6D6): δ 16.2 (s) ppm. H NMR
(C6D6): δ -0.15 (s, 9H, SiMe3), 3.91 (d, 1H, JHH ) 14.7 Hz, CHH),
4.93 (d, 1H, JHH ) 14.7 Hz, CHH), 5.16 (s broad, 5H, Cp), 5.83 (s
3
broad, 5H, Cp), 6.18 (d, 1H, JHP ) 4.4 Hz, dCH), 7.21-8.26 (m,
14H, CHarom) ppm. 13C{1H} NMR (C6D6): δ -0.8 (s, SiMe3), 55.9 (s,
CH2), 99.6 (s, dCH), 107.4 (s, Cp), 108.0 (s, Cp), 110.4 (d, JCP
)
42.2 Hz, HCdCP), 118.3, 119.2, 122.2 and 123.1 (s, CHarom), 118.9
(d, JCP ) 25.1 Hz, CdN), 124.8 (d, JCP ) 11.6 Hz, CCN), 129.0-
130.5 (m, o-PPh2 and m-PPh2), 133.2 (s broad, p-PPh2), 144.3 (d, 3JCP
) 11.4 Hz, CCCdN) ppm. i-PPh2 not observed.
7b. To a solution of 1 (0.162 g, 0.319 mmol) in toluene (5 mL) was
added 2,6-dimethylphenyl isocyanide (2b) (0.042 g, 0.319 mmol) at
room temperature. The mixture was stirred for 15 min at room temper-
ature. HCl (1 M in Et2O) (0.640 mL, 0.640 mmol) was then added to
the resulting green solution at -78 °C. Immediately, the color of the
solution changed from green to orange. The reaction mixture was then
evaporated to dryness, and the solid residue was extracted with pentane
(25 mL) and filtered. Compound 7b was obtained as a yellow solid in
73% yield (0.098 g) after solvent removal. 31P{1H} NMR (C6D6): δ
4b. To a solution of 1 (0.194 g, 0.383 mmol) in C6D6 (5 mL) was
added 2,6-dimethylphenyl isocyanide (2b) (0.050 g, 0.383 mmol) at
room temperature. The resulting green solution was stirred at room
temperature for 15 min, leading to the formation of complex 4b in
almost quantitative yield, as monitored by 31P{1H} NMR spectroscopy.
31P{1H} NMR (C6D6): δ 8.7 (s) ppm. 1H NMR (C6D6): δ 1.95 (s, 3H,
CH3), 2.47 (s, 3H, CH3), 5.19 (d, 5H, JHP ) 1.2 Hz, Cp), 5.65 (d, 5H,
JHP ) 1.1 Hz, Cp), 6.43 (d, 1H, JHP ) 4.5 Hz, dCH), 6.57-8.08 (m,
17H, CHarom) ppm. 13C{1H} NMR (C6D6): δ 21.1 (s, CH3), 23.2 (s,
CH3), 99.0 (s, dCH), 106.8 (d, JCP ) 37 Hz, HCdCP), 108.3 (s, Cp),
110.0 (s, Cp), 118.4, 119.9, 121.0, 122.5 and 124.7 (s, CHarom), 128.8-
134.6 (m, CHarom, o-PPh2, m-PPh2, and p-PPh2), 132.2 and 133.7 (s,
CCH3), 136.2 (d, JCP ) 27.5 Hz, CdN), 142.9 (d, JCP ) 11.1 Hz, CCN),
155.5 (s, CCCdN) ppm. i-PPh2 and CCCH3 not observed.
1
-31.2 (s) ppm. H NMR (C6D6): δ 2.14 (s, 6H, CH3), 3.31 (s, 2H,
CH2), 6.08 (d, 1H, JHP ) 4.7 Hz, NH), 6.57-7.91 (m, 17H, CHarom
)
ppm. 13C{1H} NMR (C6D6): δ 19.3 (s, CH3), 38.6 (s, CH2), 103.0 (d,
JCP ) 7.0 Hz, CdCP), 124.7, 126.7, 126.8 and 127.2 (s, CHarom), 128.8
(d, JCP ) 10.4 Hz, o-PPh2 or m-PPh2), 129.1, 129.2 and 129.7 (s, p-PPh2
and CHarom), 134.0 (d, JCP ) 18.7 Hz, o-PPh2 or m-PPh2), 137.8 (s,
1
CCH3), 139.4 (d, JCP ) 7.3 Hz, i-PPh2), 139.7 (s, CCCH3), 141.3 (d,
JCP ) 6.1 Hz, CdCP), 147.1 (s, CCH2), 155.1 (d, JCP ) 18.7 Hz, CCd
CP) ppm. MS (DCI): m/z 420 [M+ + 1]. Anal. Calcd for C29H26PN:
C, 83.03; H, 6.24; N, 3.33. Found: C, 82.93; H, 6.17; N, 3.40.
8b. To a solution of 7b (0.150 g, 0.357 mmol) in THF (10 mL) was
added an excess of sulfur (0.457 g, 1.785 mmol) at room temperature.
The mixture was stirred for 1 h and then evaporated to dryness. The
solid residue was extracted with diethyl ether (50 mL) and filtered.
The volatiles were removed from the solution, and the resulting solid
residue was transferred to a SiO2 chromatography column. Elution with
dichloromethane gave a red band, from which compound 8b was
isolated in 65% yield (0.104 g) after solvent removal. Mp: 158-159
5b. To a solution of 1 (0.599 g, 1.18 mmol) in toluene (10 mL) was
added 2,6-dimethylphenyl isocyanide (2b) (0.155 g, 1.18 mmol) at room
temperature. A change of color from brown to green was observed.
The mixture was stirred for 15 min and then evaporated to dryness.
The orange solid residue was extracted with pentane (25 mL) and
filtered. Compound 5b was obtained as an orange solid in 67% yield
(0.330 g) after solvent removal. 31P{1H} NMR (C6D6): δ -23.9 (s)
ppm. 1H NMR (C6D6): δ 1.87 (s, 6H, CH3), 6.42-7.66 (m, 18H, CHarom
and dCH) ppm. 13C{1H} NMR (C6D6): δ 18.6 (s, CH3), 121.9, 124.2,
125.0, 128.3, 128.8 and 129.1 (s, CHarom), 125.1 (s, CCH3), 129.3 (d,
JCP ) 11.1 Hz, o-PPh2 or m-PPh2), 132.0 (s, p-PPh2), 135.0 (d, JCP
)
1
1
20.2 Hz, o-PPh2 or m-PPh2), 137.5 (d, JCP ) 9.6 Hz, i-PPh2), 144.1
(d, JCP ) 14.6 Hz, HCdCP), 145.5 (s, CCCdN), 146.4 (s, HCdCP),
150.1 (s, CCdN), 168.7 (d, JCP ) 16.6 Hz, CdN) ppm. CCCH3 not
observed. MS (DCI): m/z 417 [M+]. Anal. Calcd for C29H24PN: C,
83.42; H, 5.79; N, 3.35. Found: C, 83.27; H, 5.70; N, 3.48.
°C. 31P{1H} NMR (C6D6): δ 31.9 (s) ppm. H NMR (C6D6): δ 2.34
(s, 6H, CH3), 3.28 (d, 2H, JHP ) 2.6 Hz, CH2), 6.73-7.27 (m, 13H,
CHarom), 8.02-8.07 (m, 4H, CHarom), 9.54 (s, 1H, NH) ppm. 13C{1H}
NMR (C6D6): δ 19.4 (s, CH3), 40.6 (d, JCP ) 10.5 Hz, CH2), 90.0 (d,
JCP ) 101.4 Hz, CdCP), 122.3, 124.7, 127.3 and 128.0 (s, CHarom),
128.9 (d, JCP ) 5.2 Hz, o-PPh2 or m-PPh2), 129.1 and 131.5 (s, p-PPh2
and CHarom), 132.6 (d, JCP ) 11.0 Hz, o-PPh2 or m-PPh2), 136.2 (d,
1JCP ) 86.7 Hz, i-PPh2), 137.6 (s, CCH3), 139.3 (s, CCCH3), 140.9 (d,
JCP ) 12.9 Hz, CdCP), 146.0 (d, JCP ) 11.8 Hz, CCH2), 159.1 (d, JCP
) 9.5 Hz, CCdCP) ppm. MS (DCI): m/z 452 [M+ + 1]. Anal. Calcd
for C29H26PNS: C, 77.07; H, 5.79; N, 3.09. Found: C, 77.14; H, 5.67;
N, 3.12.
6b. To a solution of 5b (0.200 g, 0.479 mmol) in THF (10 mL) was
added an excess of sulfur (0.614 g, 2.395 mmol) at room temperature.
The mixture was stirred for 1 h and then evaporated to dryness. The
solid residue was extracted with pentane (50 mL) and filtered. The
volatiles were removed, and the resulting solid residue was transferred
to a SiO2 chromatography column. Elution with a mixture dichlo-
romethane/pentane (1/4) gave a red band, from which compound 6b
was isolated in 82% yield (0.176 g) after solvent removal. Mp: 160-
12a. To a solution of 11 (0.211 g, 0.460 mmol) in toluene (5 mL)
was added trimethylsilylmethyl isocyanide (2a) (0.064 mL, 0.460 mmol)
at -20 °C. The mixture was allowed to reach room temperature and
stirred for an additional 2 h, leading to an orange solution. The solution
was then evaporated to dryness, and the resulting solid residue was
extracted with a mixture of THF/pentane (5 mL/40 mL) and filtered.
The volatiles were removed from the solution, and the resulting solid
was washed with pentane (5 mL) to give 12a as a yellow solid in 82%
yield (0.216 g). 31P{1H} NMR (C6D6): δ -2.3 (s) ppm. 1H NMR
(C6D6): δ 0.11 (s, 9H, SiMe3), 1.50-2.40 (m, 4H, CH2), 2.91 (d, 1H,
JHP ) 7.1 Hz, CHP), 3.16 (dt, 1H, JHP ) 10.5 Hz, JHH ) JHH′ ) 2.3
Hz, CH), 3.80 (broad, 2H, CH2Si), 5.52 (s, 5H, Cp), 5.67 (s, 5H, Cp),
7.05-7.55 (m, 9H, CHarom) ppm. 13C{1H} NMR (C6D6): δ 1.1 (s,
SiMe3), 24.8 (d, JCP ) 13.8 Hz, CH2P), 46.0 (d, JCP ) 22.9 Hz, CHP),
47.2 (d, JCP ) 7.4 Hz, CH2), 58.0 (d, JCP ) 2.7 Hz, CH), 40.2 (s,
CH2Si), 107.2 (s, Cp), 107.6 (s, Cp), 122.9, 124.1 and 128.7 (s, CHarom),
1
161 °C. 31P{1H} NMR (C6D6): δ 32.6 (s) ppm. H NMR (C6D6): δ
1.66 (s, 6H, CH3), 6.38-7.16 (m, 13H, CHarom), 8.12-8.24 (m, 4H,
CHarom), 8.41 (d, 1H, JHP ) 11.5 Hz, dCH) ppm. 13C{1H} NMR
(C6D6): δ 18.6 (s, CH3), 124.0, 124.6, 125.4 and 128.6 (s, CHarom),
124.8 (s, CCH3), 128.9 (d, JCP ) 11.4 Hz, o-PPh2 or m-PPh2), 130.4,
131.6 and 132.2 (s, CHarom and p-PPh2), 133.5 (d, JCP ) 11.6 Hz, o-PPh2
or m-PPh2), 135.6 (d, JCP ) 89.3 Hz, HCdCP or i-PPh2), 136.6 (d, JCP
) 85.6 Hz, HCdCP or i-PPh2), 142.6 (d, JCP ) 16.2 Hz, CCCdN),
149.8 (s, CCdN), 157.6 (d, JCP ) 10.7 Hz, HCdCP), 166.0 (d, JCP
)
+
7.1 Hz, CdN) ppm. CCCH3 not observed. MS (DCI): m/z 450 [M+
1]. Anal. Calcd for C29H24PNS: C, 77.47; H, 5.38; N, 3.11. Found: C,
77.52; H, 5.17; N, 3.20.
7a. A solution of complex 3a (0.250 g, 0.402 mmol) in toluene (10
mL) was stirred at room temperature for 7 days. A color change from
yellow to green was observed. HCl (1 M in Et2O) (0.804 mL, 0.804
mmol) was then added at -78 °C. Immediately, the color of the solution
changed from green to orange. The reaction mixture was then
evaporated to dryness, and the resulting solid residue was extracted
with pentane (25 mL) and filtered. Compound 7a was obtained as a
yellow solid in 60% yield (0.097 g) after solvent removal. 31P{1H}
3
129.24 (broad, o-PPh and p-PPh), 131.8 (d, JCP ) 17.3 Hz, m-PPh),
1
139.0 (d, JCP ) 29.0 Hz, i-PPh), 144.3 (s, CHarom), 150.7 (s, Carom),
168.6 (s, ZrsCarom), 227.9 (s, CdN) ppm. Anal. Calcd for C31H36-
PNSiZr: C, 64.99; H, 6.33; N, 2.44. Found: C, 64.85; H, 6.28; N,
2.50.
1
NMR (C6D6): δ -26.7 (s) ppm. H NMR (C6D6): δ -0.01 (s, 9H,
13a. To a solution of 12a (0.286 g, 0.500 mmol) in toluene (5 mL)
was added 1 equiv of HCl (1 M in Et2O, 0.5 mL, 0.500 mmol) at -78
SiMe3), 3.29 (s, 2H, CH2), 3.33 (s, 2H, CH2), 6.22 (s, 1H, NH), 7.03-

11092 J. Am. Chem. Soc., Vol. 121, No. 48, 1999
Cadierno et al.
°C. The solution was then warmed to room temperature and stirred for
an additional 1 h. The resulting solution was evaporated to dryness to
give 13a as a yellow solid in 91% yield (0.276 g). 31P{1H} NMR
(C6D6): δ 4.4 (s) ppm. 1H NMR (C6D6): δ 0.03 (s, 9H, SiMe3), 2.22-
2.63 (m, 5H, 2CH2 and CH), 3.43 (dd, 1H, JHH ) 2.9 Hz, JHP ) 12.5
Hz, PCH), 3.80 (broad, 1H, CH2Si), 4.07 (broad, 1H, CH2Si), 6.29 (s,
5H, Cp), 6.31 (s, 5H, Cp), 7.17-7.70 (m, 10H, CHarom) ppm. 13C{1H}
NMR (C6D6): δ 1.0 (s, SiMe3), 24.3 (d, JCP ) 24.9 Hz, CH2P), 34.7
(s, CH2Si), 41.8 (s, CH2), 50.4 (s, CH), 56.5 (d, JCP ) 21.1 Hz, CHP),
109.5 (s, Cp), 109.6 (s, Cp), 126.8, 128.5, and 128.7 (s, CHarom), 129.1
(d, 2JCP ) 6.1 Hz, o-PPh), 129.4 (s, p-PPh), 131.7 (d, 3JCP ) 19.3 Hz,
on a STOE IPDS equipped with an Oxford Cryosystems cooler device
and using Mo KR radiation (λ ) 0.710 73 Å). Crystal decay was
monitored by measuring 200 reflections by image, and the final unit
cell was obtained by the least-squares refinement of a setting of 5000
reflections.
Only statistical fluctuations were observed in the intensity monitors
over the course of the data collection; no absorption corrections were
applied on the data.
The three structures were solved by using direct methods (SIR92)24
and refined by least-squares procedures on Fobs; H atoms were located
on difference Fourier maps, but they were introduced in calculation in
idealized positions (dC-H ) 0.96 Å) with isotropic thermal parameters
fixed at 20% higher than those of the carbon to which they were
connected, and their atomic coordinates were recalculated after each
cycle of refinement. Exceptions to this were some specific H atoms,
H(2) for 6b and the hydrogen of the amine function of 8b, which have
been isotropically refined.
Concerning the structure 3a, the crystal forms twin motifs in the
wrong orthorhombic system of space group P212121; the data have been
indexed and resolved in monoclinic system P21, and the refinement
was performed by using a specific twin operator. The absolute
configuration of 3a was assigned on the basis of refinement of Flack’s
parameter, x,25 which is the fractional contribution of F(-h) to the
calculated structure, to the amplitude, as given in the following formula:
1
m-PPh), 140.5 (d, JCP ) 27.4 Hz, i-PPh2), 142.3 (s, CCH), 229.7 (d,
JCP ) 15.1 Hz, CdN). Anal. Calcd for C31H37PNSiClZr: C, 61.10; H,
6.11; N, 2.29. Found: C, 61.12; H, 5.92; N, 2.31.
14b. To a solution of 11 (0.184 g, 0.400 mmol) in toluene (5 mL)
was added 2,6-dimethylphenyl isocyanide (2b) (0.052 g, 0.400 mmol)
at -20 °C. The mixture was allowed to reach room temperature and
stirred for an additional 90 min, leading to a red solution. The solution
was then evaporated to dryness to give 14b as a red solid in 92% yield
1
(0.200 g). 31P{1H} NMR (C6D6): δ 1.1 (s) ppm. H NMR (C6D6): δ
1.73-2.39 (m, 4H, CH2), 1.83 (s, 3H, CH3), 2.61 (s, 3H, CH3), 3.17
(d, 1H, JHH ) 6.1 Hz, CH), 3.68 (m, 1H, CHP), 5.12 (s, 5H, Cp), 5.62
(s, 5H, Cp), 6.90-7.56 (m, 12H, CHarom) ppm. 13C{1H} NMR (C6D6):
δ 19.0 (s, CH3), 19.3 (s, CH3), 25.4 (d, JCP ) 16.0 Hz, CH2P), 34.2 (s,
CH2), 50.6 (s, CH), 56.5 (d, JCP ) 20.6 Hz, CHP), 106.1 (s, Cp), 107.4
(s, Cp), 117.4 (d, JCP ) 3.5 Hz, CCN), 125.0 (d, JCP ) 17.0 Hz, CN),
125.2, 126.1, 127.7 and 128.7 (s, CHarom), 128.9 (broad, o-PPh and
p-PPh), 129.4 and 129.7 (s, CHarom), 130.7 (d, 3JCP ) 15.2 Hz, m-PPh),
132.2 (s, CCH3), 134.7 (d, JCP ) 2.0 Hz, CCH3), 136.3 (s, CHarom),
141.3 (d, 1JCP ) 29.5 Hz, i-PPh), 147.6 (d, JCP ) 2.2 Hz, CCH), 149.3
(s, CCCH3) ppm. Anal. Calcd for C35H34PNZr: C, 71.14; H, 5.79; N,
2.37. Found: C, 71.08; H, 5.82; N, 2.40.
Fc2 ) (1 - x)F(h)2 + xF(-h)2
This parameter is sensitive to the polarity of the structure and was found
to be close to 0, which clearly indicated the good choice of the
enantiomer refined.
For whole models, refinements were carried out by minimizing the
function ∑w(||Fo| - |Fc||)2, where Fo and Fc are respectively the
observed and calculated structures factors. In the last cycles of
refinement, a scheme of ponderation was used,26 and the models reached
convergence with the following formula:
15b. To a solution of 11 (0.239 g, 0.520 mmol) in toluene (5 mL)
was added 2,6-dimethylphenyl isocyanide (2b) (0.068 g, 0.520 mmol)
at -20 °C. The reaction mixture was stirred overnight at room
temperature to give a red solution. Solvents were evaporated to dryness,
and the solid residue was extracted with pentane (30 mL) and filtered.
Compound 15b was obtained as an orange solid in 72% yield (0.138
R )
(||Fo| - |Fc||)/ |Fo|
∑
∑
Rw ) [ w(||Fo| - |Fc||)2/ w(|Fo|)2]1/2
1
g) after solvent removal. 31P{1H} NMR (C6D6): δ 9.1 (s) ppm. H
∑
∑
NMR (C6D6): δ 1.18-2.31 (m, 4H, CH2), 2.17 (s, 3H, CH3), 2.80 (s,
3H, CH3), 3.46 (dd, 1H, JHH ) 3.4 Hz, JHP ) 6.8 Hz, PCH), 3.63 (m,
1H, CH), 6.39-7.30 (m, 11H, CHarom), 8.36 (d, 1H, JHH ) 7.5 Hz,
CHarom) ppm. 13C{1H} NMR (C6D6): δ 20.0 (s, CH3), 20.2 (s, CH2),
23.1 (d, JCP ) 17.1 Hz, CH2P), 33.4 (d, JCP ) 4.4 Hz, CH2), 49.6 (s,
CH), 55.1 (d, JCP ) 26.8 Hz, CHP), 123.5, 123.8, 124.0, 127.7, 128.5,
129.1 and 133.0 (s, CHarom), 129.2 (d, 2JCP ) 3.5 Hz, o-PPh), 129.8 (s,
The calculation were performed with the aid of the CRYSTALS
programs27 running on a PC, and the molecules were drawn with
CAMERON,28 with thermal ellipsoids fixed at the 50% probability level.
The atomic scattering factors were taken from International Tables for
X-Ray Crystallography.29
3
3
p-PPh), 130.2 (d, JCP ) 12.8 Hz, m-PPh), 139.2 (d, JCP ) 28.2 Hz,
i-PPh2), 140.4 (s, CCdN), 151.8 (d, JCP ) 1.6 Hz, CCCdN), 152.0 (s,
CMe), 175.0 (d, JCP ) 14.4 Hz, CdN) ppm. MS (DCI/NH3): m/z 370
[M+ + 1]. Anal. Calcd for C25H24PN: C, 81.27; H, 6.54; N, 3.79.
Found: C, 81.19; H, 6.50; N, 3.82.
Acknowledgment. Financial support of this work by the
CNRS (France) and KBN (Poland) is gratefully acknowledged.
V.C. thanks the Spanish Ministerio de Educacion y Cultura for
a postdoctoral fellowship.
15c. To a solution of 11 (0.202 g, 0.440 mmol) in toluene (5 mL)
was added tert-butyl isocyanide (2c) (0.370 g, 0.440 mmol) at -20
°C. The reaction mixture was stirred at room temperature for 5 h to
give a yellow solution. Solvents were evaporated to dryness, and the
solid residue was extracted with diethyl ether (20 mL) and filtered.
Compound 15c was obtained as a yellow powder in 62% yield (0.088
Supporting Information Available: Tables of data collec-
tion parameters, atom coordinates, bond distances and angles,
anisotropic thermal parameters, and hydrogen coordinates
(PDF). This material is available free of charge via the Internet
at http://pubs.acs.org.
1
g) after solvent removal. 31P{1H} NMR (CDCl3): δ 13.5 (s) ppm. H
JA990502G
NMR (CDCl3): δ 1.43 (s, 9H, CH3), 1.21-2.12 (m, 4H, CH2), 2.51
(m, 1H, PCH), 4.13 (m, 1H, CH), 7.22-7.58 (m, 8H, CHarom), 7.79 (d,
1H, JHH ) 7.6 Hz, CHarom) ppm. 13C{1H} NMR (CDCl3): δ 27.1 (d,
JCP ) 15.6 Hz, CH2P), 31.3 (d, JCP ) 5.5 Hz, CH3), 32.4 (d, JCP ) 4.7
(24) Altomare, A.; Cascarano, G.; Giacovazzo, G.; Guargliardi, A.; Burla,
M. C.; Polidori, G.; Camalli, M. SIR92, a Program for Automatic Solution
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Hz, CH2), 48.1 (d, JCP ) 23.1 Hz, CHP), 49.4 (s, CH), 56.3 (d, JCP
)
1.8 Hz, CCH3), 122.6, 123.4, 127.5 and 128.2 (s, CHarom), 128.3 (d,
3
2JCP ) 3.6 Hz, o-PPh), 130.8 (s, p-PPh), 131.5 (d, JCP ) 17.6 Hz,
m-PPh), 138.9 (d, JCP ) 28.7 Hz, i-PPh), 142.8 (s, CCdN), 148.0 (s,
CCCdN), 167.0 (d, JCP ) 16.4 Hz, CdN) ppm. MS (DCI/NH3): m/z
322 [M+ + 1]. Anal. Calcd for C21H24PN: C, 78.47; H, 7.52; N, 4.35.
Found: C, 78.37; H, 7.60; N, 4.37.
X-ray Analysis of 3a, 6b, and 8b. For whole compounds, the X-ray
diffraction analyses were carried out at low temperature (T ) 160 K)