Remarkable product diversity in the "self-organized" reaction of deprotonated acetonitrile with chlorophosphines

Article abstract of DOI:10.1021/ja905676a

This study examined the reaction of in situ deprotonated acetonitrile with different chlorophosphines ClPR₂ (5a-d) to find new nitrile functionalized bis(diphenylphosphino)methane (dppm) ligands. Depending on the steric and electronic demand of

Full text of DOI:10.1021/ja905676a

Published on Web 11/17/2009
Remarkable Product Diversity in the “Self-Organized”
Reaction of Deprotonated Acetonitrile with Chlorophosphines
Kirsten Spannhoff, Nadine Kuhl, Gerald Kehr, Roland Fro¨hlich, and Gerhard Erker*
Organisch-Chemisches Institut der UniVersita¨t Mu¨nster, Corrensstrasse 40,
48149 Mu¨nster, Germany
Received July 9, 2009; E-mail: erker@uni-muenster.de
Abstract: This study examined the reaction of in situ deprotonated acetonitrile with different chlorophos-
phines ClPR2 (5a-d) to find new nitrile functionalized bis(diphenylphosphino)methane (dppm) ligands.
Depending on the steric and electronic demand of the phosphines, very different and unexpected products
(1b, 6, 9b and 11) were found. In the case of aryl-substituted phosphines (ClPPh2 (5a) and ClPMes2 (5b)),
bis(diarylphosphino)acetonitrile compounds (1a and 1b) were found. Introduction of alkyl substituents at
the ClPR2 fragment (R ) tbutyl (5c) and cyclohexyl (5d)) changes the overall reaction behavior drastically.
A new heteropentafulvene type structure (6), a P/N-disubstituted acetylene (9), and a P-substituted
3-amidocrotononitrile species (11) were found. Considering the experimental simplicity of these three-
component reactions, these products are complex and their formations are highly organized. Most
compounds were characterized by X-ray diffraction, NMR spectroscopy, and elemental analysis.
Scheme 1
Introduction
Bis(diphenylphosphino)methane (dppm) is a very important
chelate ligand system in coordination chemistry and catalysis.1
We have recently described the closely related cyano-substituted
analogue (1a, dppm-CN).2 In addition to bearing the additional
functional group, this system shows the advantageous feature
of being markedly more acidic. Its bis-P-oxides, -sulfides and
-imines (2-4) were prepared; the bis(phosphinimine) 4 is
exclusively found in the favored NH tautomeric form (see
Scheme 1).3 These systems form interesting coordination
compounds, mostly in their monoanionic state.4 The phosphorus-
based chelate ligands5 show interesting properties when com-
pared to their related carbon centered analogues, for example,
the ubiquitous acac6 or nacnac7 metal complex systems.
The parent dppm-CN chelate system (1a) is easily prepared
by a remarkably simple one-pot reaction. Treatment of aceto-
nitrile with n-butyl lithium followed by chlorodiphenylphosphine
(5a) in a 1:1:1 ratio in tetrahydrofuran directly gave the product
NC-CH(PPh2)2 (1a) in a reasonable yield (66%, relative to the
base equivalents used) after conventional workup. Although
using an apparently “wrong” stoichiometric ratio of reagents,
this simple procedure gave the interesting product dppm-CN
(1a) in an easy way and acceptable yield under these carefully
optimized reaction conditions. We assume that the initially
formed Ph2P-CH2-CN intermediate was rapidly deprotonated
and the corresponding anion trapped by the ClPPh2 reagent to
yield 1a. The possible third deprotonation/phosphination was
apparently not favored under the applied reaction conditions.
This observation made us aware of the great synthetic potential
that such a system might specifically have, namely, to allow
the selective preferred formation of a single compound out of
a complicated manifold of possible products by the choice of
one specific reagent under otherwise standard conditions. In
other words, it needed to be tested whether various possible
phosphination products of our substrate example acetonitrile
could selectively be obtained under just the same simple (or
similar) reaction conditions, as they were schematically outlined
above for the formation of 1, just by changing the substituents
of the chlorophosphine reagent ClPR2 (5) used. Actually, this
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9
17836 J. AM. CHEM. SOC. 2009, 131, 17836–17842
10.1021/ja905676a CCC: $40.75  2009 American Chemical Society

Reaction of Acetonitrile with Chlorophosphines
A R T I C L E S
turned out to be true for this overall reaction scheme: we
observed the selective formation of a remarkable variation of
phosphination products of acetonitrile under our simple standard
reaction conditions (or conditions related to them) by just
changing the substituents of the ClPR2 reagent (5). Several
remarkable examples of such a “self-organized” reaction type
are described in this article.
Results and Discussion
We first changed the steric bulk of the aryl substituents at
the reagent 5 by employing the considerably more bulky
chlorodimesitylphosphine reagent (5b) under otherwise un-
changed reaction conditions, that is, by employing the reagents
CH3CN, n-butyl lithium and ClP(mesityl)2 in a 1:1:1 ratio. This
did not change the favored reaction pathway: we isolated the
bis(dimesitylphosphino)acetonitrile product (1b, see Figure 1)
as a white solid in 50% yield, calculated on the basis of the
molar equivalents of base used, which, of course, corresponds
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Figure 1. Molecular structure of compound 1b.
Scheme 2
only to a yield of 25% based on the cheap acetonitrile starting
material. Repeating the reaction with the “correct” 1:2:2
stoichiometry of acetonitrile, n-butyl lithium base and chlo-
rodimesitylphosphine gave product 1b in 53% yield (see Scheme
2). As this yield corresponds equally to any reagent employed
in the “correct” 1:2:2 stoichiometry, this practically means that
the yield was doubled relative to our previous “standard” (i.e.,
1:1:1) conditions.
Compound 1b was characterized by C,H,N elemental analysis,
spectroscopically and by X-ray diffraction. It features a strong
ν˜(CtN) IR band at 2223 cm-1. The 31P NMR signal is found
at δ -19.3 (in d6-benzene). The 13C NMR features of the
´
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[P]2CHCN moiety are observed at δ 118.4 (t, JPC ) 5.9 Hz,
1
1
CtN) and δ 27.6 [t, JPC ) 38.1 Hz, CH, corresponding H
NMR signal at δ 5.66 (t, 2JPH ) 7.6 Hz, 1H)]. The product 1b
is prochiral and it features a pair of nonplanar tricoordinated
phosphorus atoms attached to the central methine carbon C1;
therefore, we observe the NMR signals of pairwise diaste-
reotopic mesityl groups at the phosphorus atoms [e.g., δ 2.52
(s, 12H)/2.41 (s, 12H), mesityl o-CH3].
Single crystals of 1b suited for the X-ray crystal structure
analysis were obtained from a benzene/pentane mixture at room
temperature. In the crystal compound 1b features a structure in
which the central carbon atom C1 is pseudotetrahedrally
coordinated by the -CtN substituent (C1-C2: 1.456(3) Å,
C2-N1: 1.149(2) Å, angle C1-C2-N1: 178.6(2)°), the single
remaining hydrogen and a pair of -P(mesityl)2 substituents
(C1-P1: 1.885(2) Å, C1-P2: 1.902(2) Å, angle P1-C1-P2:
106.6(1)°). Each P atom features a nonplanar coordination
geometry (e.g., angles C1-P1-C11: 110.5(1)°, C1-P1-C21:
105.7(1)°, C11-P1-C21 105.2(1)°/C1-P2-C31: 110.6(1)°,
C1-P2-C41: 98.6(1)°, C31-P2-C41: 103.1(1)°). We note that
both the structures of 1a (see above) and 1b are very similar as
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Parvez, M. Chem.sEur. J. 2007, 13, 2632–2640. (f) Jeske, R. C.;
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A R T I C L E S
Spannhoff et al.
Scheme 3
Scheme 4
These structural data indicate that the heterocyclic core of
compound 6 is markedly polarized. It is probably best schemati-
cally represented by a resonance hybrid description between
the canonical mesomeric formulas 6A and 6B (see Scheme 3).
This is supported by some of the characteristic spectroscopic
parameters of 6. The 1H NMR spectrum features a 2H intensity
signal of the exocyclic methylene group at δ 3.64. We monitor
the 31P/1H NMR signal pairs of a total of four different PtBu2
moieties [P6: δ 128.8/1.33 (3JPH ) 10.9 Hz), P3: δ 36.9 (3JPP
) 3.7 Hz)/1.36 (3JPH ) 10.6 Hz), P1: δ 82.1/1.39 (3JPH ) 14.7
Hz), P4: δ 30.4/1.55 (3JPH ) 12.0 Hz)]. The carbon NMR
resonances of the heterocyclic core of 6 occur at δ 204.6
(tentatively assigned to C3), δ 106.9 (C4) and δ 179.8 (C5).
The 13C NMR signal of the methylene group was found at δ
32.8 (for coupling constants and further details see the Experi-
mental Section and the Supporting Information).
Apparently in the base-induced reaction with the ClPtBu2
reagent (5c) acetonitrile was overall twice deprotonated and,
consequently, twice phosphorylated, similar as in the reaction
with the aromatic ClPAr2 reagents 5a and 5b. However, the
obtained product (6) indicates that here a sequence of P-C/
P-N (or Vice Versa) bond formations has occurred. We assume
that this has led to the formation of the doubly phosphorylated
ketenimine intermediate (7), which was, however, not observed
directly.8 Under the applied reaction conditions the ketenimine
is not stable but undergoes a specific dimerization reaction
(possibly involving intermediate deprotonation) to eventually
yield the final observed product 6 (see Scheme 4).9 The
formulated tautomerization step seems to take place prior to
the workup; we obtained the product (6-D2) with a pendant
-CD2PtBu2 group >75% deuterated from the analogous treatment
of CD3CN with the n-butyl lithium base and ClPtBu2 (5c) (for
details see the Supporting Information).
are their modes of formation. The actually observed reaction
pathway did not respond to changing the bulk of the aryl groups
at the ClPAr2 reagents even when going from phenyl groups to
the much more bulky mesityl substituents.
The overall reaction behavior changed drastically by the
introduction of bulky alkyl substituents at the ClPR2 reagent.
The reaction between acetonitrile, n-butyl lithium and di-tert-
butylchlorophosphine (5c) in a 1:1:1 molar ratio was carried
out under our standard conditions. After conventional workup
we isolated the heterocyclic product 6 (see Scheme 3) in ca.
19% yield as a yellow solid. The product 6 was identified by
X-ray crystal structure analysis, and the compound was then
further characterized spectroscopically and by C,H,N elemental
analysis.
Compound 6 features a distorted heteropentafulvene type core
structure in the crystal (see Figure 2). The central five-membered
ring contains a long, probably strongly polarized CdC double
bond (C3-C4: 1.432(3) Å) which is in conjugation with an
electron-donating R3P ) N- unit (P4-N6: 1.651(2) Å, C4-N6:
1.328(3) Å, angles P4-N6-C4: 108.7(1)°, N6-C4-C3:
121.7(2)°) and an electron-withdrawing phosphinimine func-
tional group at the sp2-carbon center C2 (C2-P4: 1.964(2) Å,
C2-C3: 1.430(3) Å, angles P4-C2-C3: 100.6(1)°, N6-P4-C2:
96.0(1)°, C71-P4-C81: 115.9(1)°, C2-C3-C4: 113.0(2)°;
tBu2-P-N)[C]: N1-C2: 1.294(3) Å, P1-N1: 1.717(2) Å,
anglesP1-N1-C2:123.1(2)°,N1-C2-P4:129.7(2)°,N1-C2-C3:
129.7(2)°). The core of the compound seems to contain a
conjugated π-system ranging from the exocyclic NdC bond
through the internal CdC and NdP double bonds, but excluding
the endocyclic C2-P4 linkage. The system is completed by the
attached substituents [tBu2P- at C3 (P2-C3: 1.835(2) Å) and
tBu2P-CH2- at C4 (C4-C5: 1.501(3) Å, C5-P3: 1.843(3) Å,
angle C4-C5-P3: 118.0(2)°)].
The observed reaction path would again require a “correct”
acetonitrile/base/chlorophosphine ratio of 1:2:2. Therefore, we
performed this reaction by treatment of CH3CN with n-butyl
lithium and ClPtBu2 (5c) in the 1:2:2 ratio. In this case we
obtained a mixture of the expected product 6 with the new
product 9a in a 2:1 ration in a combined yield of ca. 35% (see
Scheme 3). The composition of the minor product 9a was
tentatively assigned from its characteristic spectroscopic data,
(8) Sung, K. J. Chem. Soc., Perkin Trans. 2 1999, 1169–1173.
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4229–4232. (d) Bestmann, H. J.; Schmid, G.; Bo¨hme, R.; Wilhelm,
E.; Burzlaff, H. Chem. Ber. 1980, 113, 3937–3941. (e) Bestmann, H. J.;
Schmid, G. Tetrahedron Lett. 1981, 22, 1679–1680. (f) Lukashev,
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Figure 2. View of the molecular geometry of compound 6.
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17838 J. AM. CHEM. SOC. VOL. 131, NO. 49, 2009

Reaction of Acetonitrile with Chlorophosphines
A R T I C L E S
Scheme 5
coordination geometry is close to trigonal planar (sum of the
bonding angles at N1: 359.4°). The N-P bond lengths were
found at 1.760(1) Å (N1-P1) and 1.756(1) Å (N1-P2),
respectively, which is shorter than the adjacent P-C(sp3)
linkages (e.g., P1-C11: 1.851(2) Å, P1-C21: 1.854(2) Å). Both
the phosphorus atoms P1 and P2 exhibit nonplanar coordination
geometries (sum of bond angles at P1: 308.4°, at P2: 307.5°).
Compound 9b shows 13C NMR features of the [N]-CtC-[P]
2
unit at δ 106.2 (t, JPC ) 10.1 Hz, [N]-Ct) and δ 55.6 (d,
1JPC ) 13.7 Hz, tC-[P]). The 31P NMR [tC]-P resonance
was found at δ -20.1, whereas the both phosphorus nuclei
bonded to the nitrogen atom give rise to a signal at δ 89.7.
The formation of the tris-phosphorylated compound 9b
eventually required 3-fold deprotonation of the acetonitrile
starting material. Therefore, the use of the three reagents
acetonitrile, n-butyl lithium and chlorodi(cyclohexyl)phosphine
in a 1:1:1 ratio, as used here, is counterintuitive. However, our
experiments employing these reagents in a 1:2:2 ratio (alterna-
tively 1:3:3) opened a favorable competitive pathway that
resulted in the formation of the known compound Cy2P-PCy2
(10) (Scheme 5).12 Apparently, halogen/lithium exchange fol-
lowed by nucleophilic P-P bond formation takes over in this
case. Compound 10 was isolated from the reaction mixture and
characterized, including X-ray diffraction (for details see the
Supporting Information).
We briefly examined how the overall reaction scheme
described in this account might change if an excess of
acetonitrile was used. To that purpose we treated acetonitrile
with n-butyl lithium and chlorodi(tert-butyl)phosphine (5c) in
THF in a 2:1:1 ratio. From the reaction mixture we isolated the
product 11 in 52% yield. Compound 11 was characterized by
an X-ray crystal structure analysis (see Figure 4). It features
the newly formed P1-N1 linkage (1.727(2) Å) and the newly
formed N-C(2)dC(4) carbon carbon bond (C2-C4: 1.353(3)
Å, C2-N1: 1.365(3) Å, angles P1-N1-C2: 126.4(2)°,
N1-C2-C4: 120.3(2)°, C2-C4-C5: 123.6(2)°). Carbon atom
C2 bears the methyl substituent, carbon atom C4 the cyano
functional group (C4-C5: 1.399(4) Å, C5-N6: 1.146(4) Å,
angle C4-C5-N6: 178.4(3)°).
Figure 3. Projection of the molecular geometry of the acetylene 9b.
obtained from the mixture, in comparison with the isolated and
fully characterized analogue 9b (see below). Typical spectro-
scopic features of compound 9a include an IR(CtC) band at ν˜
) 2113 cm-1, an ESI-MS-EM feature at m/z ) 474.3547 [M
+ H]+, and 31P NMR resonances at δ 122.4 (2P) and δ 23.8 (t,
4JPP ) 2.5 Hz, 1P).
In addition to the observed competing formation of 9a, we
have obtained some evidence for the proposed N/C phospho-
rylation pathway from the related reaction of acetonitrile/n-butyl
lithium with chlorodi(cyclohexyl)phosphine (5d). The reaction
was again first carried out under our standard reaction conditions
employing a 1:1:1 ratio of the reagents. Conventional workup
gave the N,N,C-tris-phosphorylated product 9b (13% yield) as
a slightly air and moisture sensitive pale yellow solid.10,11 Single
crystals suited for X-ray crystal structure analysis of the P/N-
disubstituted acetylene 9b were obtained from toluene at ambient
temperature.
Thecrystalcompound9bfeaturesalinearcentral[N]-CtC-[P]
core with a C2-C3 (1.201(2) Å) carbon carbon triple bond
(bond angles P3-C3-C2: 171.4(2)°, C3-C2-N1: 179.2(2)°)
(see Figure 3). The C(sp)-P bond is rather short (C3-P3:
1.757(2) Å) compared to the adjacent C(sp3)-P linkages
(P3-C51/C61: 1.861(2)/1.860(2) Å). The phosphorus center P3
is pyramidalized (sum of the CPC angles: 306.7°). The other
end of the C3-C2 triple bond bears the -N(PCy2)2 substituent.
The C2-N1 bond length amounts to 1.352(2) Å. The nitrogen
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883–904.
(11) For organic reactions of R-metallated nitrile substrates see, for
example: (a) Fleming, F. F.; Liu, W. Eur. J. Org. Chem. 2009, 69,
9–708. (b) Fleming, F. F.; Shook, B. C Tetrahedron 2002, 58, 1–23.
(12) (a) Richter, R.; Kaiser, J.; Sieler, J.; Hartung, H.; Peter, C. Acta
Crystallogr. 1977, B33, 1887–1892. (b) Dodds, D. L.; Haddow, M. F.;
Orpen, A. G.; Pringle, P. G.; Woodward, G. Organometallics 2006,
25, 5937–5945.
Figure 4. Molecular structure of compound 11.
9
J. AM. CHEM. SOC. VOL. 131, NO. 49, 2009 17839

A R T I C L E S
Spannhoff et al.
Scheme 6
obtained rather selectively by simple one-pot-procedures, albeit
in low yields, by applying our standard reaction and workup
conditions. This seems to indicate a remarkable potential of
“self-organization” of these reactions under rather simple
practical experimental conditions.
Experimental Section
Compound 11 features characteristic NMR data [1H: δ 4.71
All reactions were carried out under an inert gas atmosphere
(argon) in Schlenk-type glassware or in a glovebox. Solvents were
dried and distilled under argon prior use. The following instruments
were used for the physical characterization of the compounds. NMR:
Bruker AC200 P-FT (31P: 81.0 MHz), Bruker AV400 (1H: 400 MHz,
13C: 101 MHz), Varian InoVa 500 (1H: 500 MHz, 13C: 126 MHz,
31P: 202 MHz), Bruker Unity Plus 600 (1H: 600 MHz, 31C: 151
MHz, 31P: 243 MHz). Most NMR assignments were supported by
additional 1D and 2D experiments. Melting points and decomposi-
tion points: Ta-Instruments “Differential-Scanning-Calorimeter
Q20” (heating-up rate: 10 °C/min). IR: Varian 3100 FT-IR
spectrometer (KBr pellet or ATR). MS: Bruker Daltronics MicroTof
(calibration directly before the sample is measured with potassium
formiate cluster). Elemental analyses: Elementar Vario El III. X-ray
structure analysis: Data sets were collected with Nonius KappaCCD
diffractometers, in case of Mo-radiation equipped with a rotating
anode generator. Programs used: data collection COLLECT (Nonius
B.V., 1998), data reduction Denzo-SMN (Otwinowski, Z.; Minor,
W. Methods Enzymol. 1997, 276, 307-326), absorption correction
SORTAV (Blessing, R. H. Acta Crystallogr. 1995, A51, 33-37;
Blessing, R. H. J. Appl. Crystallogr. 1997, 30, 421-426) and Denzo
(Otwinowski, Z.; Borek, D.Majewski, W.; Minor, W. Acta Crys-
tallogr. 2003, A59, 228-234), structure solution SHELXS-97
(Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467-473), structure
refinement SHELXL-97 (Sheldrick, G. M. Acta Crystallogr. 2008,
A64, 112-122), graphics XP (BrukerAXS, 2000).
2
(br., 1 H, CHCN), δ 4.46 (NH); 13C: δ 165.0 (d, JPC ) 16.5
Hz, N-Cd), δ 68.6 (d, 3JPC ) 20.7 Hz, )C(CN)), δ 121.3 (d,
4JPC ) 2.1 Hz, CN); 31P: δ 61.2]. It shows a strong IR(CtN)
band at ν˜ ) 2199 cm-1. Apparently, under these reaction
conditions the carbanion generated from acetonitrile added to
a second CH3CN molecule, followed by phosphine trapping/
tautomerization to yield 11 (Scheme 6). Related product
formation had previously been observed in base-induced meta-
lation reactions of acetonitrile with group 14 main group metal
reagents.13-15
Conclusions
The base induced three-component reactions of acetonitrile
with the diaryl- or dialkylchlorophosphines (5) show a remark-
able variability in the favored reaction courses taken. All these
reactions presumably take place Via the respective monoanion
intermediates, generated in situ in cascades that depend critically
on the specific reaction conditions and phosphorus reagents
chosen.
Generating the acetonitrile monoanion in an excess of the
acetonitrile starting material resulted in a rapid trapping reaction
toward the formation of the C-C coupling product 11. The
alternative scenario was met when the acetonitrile anion was
generated in the presence of both two molar equivalents of base
and the ClPMes2 reagent. In this case we must assume the
formation of a Mes2P-CH2CN intermediate that undergoes
subsequent deprotonation and phosphorylation to give the
“DArPM-CN” chelate phosphine derivative 1b in a fair yield.
It is interesting to note that the base induced reactions of
acetonitrile follow different pathways in the case of treatment
with the dialkylphosphines (5c, 5d). At the same time these
reactions seem to be critically dependent on the specific reaction
conditions chosen. Both these systems feature N,C-bis-phos-
phorylation pathways. In the case of ClPtBu2 the resulting
General Procedure. All compounds were synthesized according
to the procedure published for the literature known compound
dppm-CN 1a: Under stirring n-butyl lithium (1.6 M in hexane) was
added to acetonitrile (dried over CaH2 and distilled prior use) in
tetrahydrofuran (20 mL) at -78 °C. After stirring for 30 min at
-78 °C and another 2.5 h at room temperature the solution was
again cooled to -78 °C and chlorodiarylphosphine 5b or chlorodi-
alkylphosphine 5c or 5d, respectively, was added drop by drop.
The reaction mixture was allowed to warm slowly to room
temperature overnight. Then the solvent was removed in Vacuo and
the residue was suspended in dichloromethane (25 mL) in order to
remove the lithium chloride by filtration over Celite. Once more
the solvent was removed in Vacuo and this time the residue was
dissolved in a small amount of ethanol (dried over Mg and distilled
prior use, 3-5 mL). After the product precipitated from solution
while stirring, it was collected by filtration and dried in Vacuo.
Compound 1b. 1b was synthesized according to the general
procedure using two different stoichiometries A (1:1:1) and B (1:
2:2) of CH3CN, n-butyl lithium, and chlorodimesitylphosphine.
Stoichiometry A: The reaction starting from 2.29 g chlorodimesi-
tylphosphine16 (7.50 mmol,17 1.50 equiv) in 10 mL tetrahydrofuran
yielded 719 mg (1.24 mmol, 50%) of compound 1b as a white air
stable solid. Stoichiometry B: The reaction of acetonitrile (125 µL,
2.38 mmol, 1.0 equiv), n-butyl lithium (3.00 mL, 4.76 mmol, 2.0
equiv), chlorodimesitylphosphine (1.45 g, 4.76 mmol, 2.0 equiv)
in 10 mL tetrahydrofuran gave 1b (724 mg, 1.25 mmol, 53%).
Single crystals suitable for X-ray structure analysis were obtained
t
alleged Bu2P-NdCdCH-PtBu2 intermediate (7) apparently
undergoes dimerization to eventually yield 6. At higher base
concentrations eventually further deprotonation/phosphorylation
is observed to give 9 [(tBu2P-): a; (Cy2P-): b], but this reaction
pathway is lost with increasing base concentrations toward the
pathway eventually leading to the competing R2P-PR2 product.
We see that an interesting array of products is arising from
the base induced phosphorylation reaction of acetonitrile. The
outcome of the specific three-component-reaction is critically
dependent in detail on the reaction conditions and the diorga-
nylchlorophosphine reagent used. However, we have found that
the described compounds, such as the doubly P,N-donor-
substituted acetylenes (9) or the remarkable “heteropentaful-
venoide” compound 6, of quite different composition can be
1
from a benzene/pentane mixture at room temperature. H NMR
([D6]-benzene, 400 MHz, 298 K): δ 6.72 (s, 4H, m-Mes′), 6.59 (s,
2
(13) For silyl acetonitriles, see: Krempner, C.; Martens, K.; Reinke, H. J.
Organomet. Chem. 2007, 692, 5799–5803, and references cited therein.
(14) For germyl acetonitriles, see: (a) Wiberg, N.; Kim, C.-K. Chem. Ber.
1986, 119, 2966–2979. (b) Subashi, E.; Rheingold, A. L.; Weinert,
C. S. Organometallics 2006, 25, 3211–3219.
4H, m-Mes), 5.66 (t, JPH ) 7.6 Hz, 1H, CH), 2.52 (s, 12H,
o-CH3Mes′), 2.41 (s, 12H, o-CH3Mes), 2.01 (s, 6H, p-CH3Mes′), 2.00
(16) Goldwhite, H.; Kaminski, J.; Millhauser, G.; Ortiz, J.; Vargas, M.;
Vertal, L. J. Organomet. Chem. 1986, 310, 21–25.
(17) Due to a 33% impurity, the initial amount of the starting material
was higher to achieve 1.0 equiv of chlorodimesitylphosphine.
(15) For the 3-amidocrotononitrile species tBu3Ge[NHC(CH3)CHCN], see:
Amadoruge, M. L.; DiPasquale, A. G.; Rheingold, A. L.; Weinert,
C. S. J. Organomet. Chem. 2008, 693, 1771–1778.
9
17840 J. AM. CHEM. SOC. VOL. 131, NO. 49, 2009

Reaction of Acetonitrile with Chlorophosphines
A R T I C L E S
(s, 6H, p-CH3Mes). 13C{1H} NMR ([D6]-benzene, 101 MHz, 298
CyPN), 2.12, 1.57 (o′-CyPC), 1.92, 1.52 (o′-CyPN), 1.87, 1.41 (o-
CyPC), 1.87, 1.36 (m-CyPN), 1.84, 1.28 (m-CyPC), 1.76, 1.27 (m-
CyPN, m-CyPC), 1.74 (i-CyPC), 1.67, 1.27 (p-CyPC), 1.65, 1.24 (p-
CyPN) [chemical shift values extracted from ghsqc NMR experiments].
2
2
K): δ 144.6 (t, JPC ) 8.2 Hz, o-Mes′), 141.8 (t, JPC ) 8.2 Hz,
1
o-Mes), 139.6 (p-Mes′), 138.2 (p-Mes), 131.7 (t, JPC ) 11.7 Hz,
3
3
i-Mes), 130.9 (t, JPC ) 1.6 Hz, m-Mes), 130.7 (t, JPC ) 1.9 Hz,
m-Mes′), 129.2 (t, 1JPC ) 7.4 Hz, i-Mes′), 118.4 (t, 2JPC ) 5.9 Hz,
CN), 27.6 (t, 1JPC ) 38.1 Hz, CH), 23.7 (t, 3JPC ) 9.7 Hz, o-CH3Mes′),
23.4 (t, 3JPC ) 9.1 Hz, o-CH3Mes), 20.9 (p-CH3Mes′), 20.7 (p-CH3Mes).
2
13C{1H} NMR ([D6]-benzene, 126 MHz, 298 K): δ 106.2 (t, JPC
) 10.1 Hz, tC-N); 55.6 (d, 1JPC ) 13.7 Hz, P-C≡), 37.7 (AXX′,
3
1
1JPC + JP’C ) 16.6 Hz, i-CyPN), 33.8 (d, JPC ) 8.4 Hz, i-CyPC),
31P{1H} NMR ([D6]-benzene, 81 MHz, 298 K): δ -19.3 (s, ν1/2
)
30.6 (d, 2JPC ) 18.4 Hz, o-CyPC), 30.1 (d, 2JPC ) 5.4 Hz, o′-CyPC),
2
4
2
2.3 Hz). Anal. calcd for C38H45NP2: C, 79.00; H, 7.85; N, 2.42.
Found: C, 78.58; H, 7.79; N, 2.33. IR (ATR): ν˜ 2223 (ν(CtN)).
Melting Point (DSC): 167 °C.
29.6 (AXX′, JPC + JP’C ) 9.9 Hz, o-CyPN), 28.9 (AXX′, JPC
+
4JP’C ) 17.7 Hz, o′-CyPN), 27.5 (d, JPC ) 6.6 Hz, m-CyPC), 27.5
3
(d, JPC ) 13.8 Hz, m′-CyPC), 27.5 (AXX′, JPC + JPC ) 7.9 Hz,
3
3
5
3
5
X-Ray Crystal Structure Analysis of 1b. Formula C38H45NP2,
M ) 577.69, colorless crystal 0.40 × 0.40 × 0.20 mm3, a )
30.2865(2), c ) 14.7582(2) Å, V ) 13537.3(2) Å3, Fcalc ) 1.134 g
cm-3, µ) 0.154 mm-1, empirical absorption correction (0.941 e
T e 0.970), Z ) 16, tetragonal, space group I41/a (No. 88), λ)
0.71073 Å, T ) 223(2) K, ω and ꢀ scans, 59657 reflections
collected ((h, (k, (l), [(sin θ)/λ] ) 0.66 Å-1, 8075 independent
(Rint ) 0.084) and 4984 observed reflections [I g 2 σ(I)], 382 refined
parameters, R ) 0.049, wR2 ) 0.136, max. residual electron density
0.21 (-0.26) e Å-3, hydrogen atoms calculated and refined as riding
atoms.
m-CyPN), 27.4 (AXX’, JPC + JPC ) 11.8 Hz, m′-CyPN), 27.0 (d,
4JPC ) 1.0 Hz, p-CyPC), 26.9 (br, p-CyPN). 31P{1H} NMR ([D6]-
benzene, 202 MHz, 298 K): δ 89.7 ([N]-P), -20.1 (s, [C]-P).
Anal. calcd for C38H66NP3: C, 72.46; H, 10.56; N, 2.22. Found: C,
72.45; H, 10.51; N, 2.24. IR (ATR): ν˜ 2128 (CtC). Melting Point
(DSC): 133.6 °C. Decomposition Point (DSC): 234.5 °C.
X-Ray Crystal Structure Analysis of 9b. Formula C38H66NP3,
M ) 629.83, colorless crystal 0.35 × 0.25 × 0.15 mm3, a )
18.0863(5), b ) 9.8117(3), c ) 21.5144(7) Å, ) 95.016(2)°,
V ) 3803.3(2) Å3, Fcalc ) 1.100 g cm-3, µ ) 1.606 mm-1
,
empirical absorption correction (0.603 e T e 0.795), Z ) 4,
monoclinic, space group P21/c (No. 14), λ) 1.54178 Å, T )
223(2) K, ω and ꢀ scans, 30001 reflections collected ((h, (k,
(l), [(sin θ)/λ] ) 0.60 Å-1, 6721 independent (Rint ) 0.042)
and 6241 observed reflections [I g 2 σ(I)], 379 refined
parameters, R ) 0.043, wR2 ) 0.120, max. residual electron
density 0.39(-0.19) e Å-3, hydrogen atoms calculated and
refined as riding atoms.
Compound 6. 6 was synthesized according to the general
procedure using CH3CN, n-butyl lithium and di-tert-butylchloro-
phosphine in a 1:1:1 ratio. The reaction of CH3CN (250 µL, 4.76
mmol, 1.0 equiv) and n-butyl lithium (3.00 mL, 4.76 mmol, 1.0
equiv) with di-tert-butylchlorophosphine (860 mg, 4.76 mmol, 1.0
equiv) gave compound 6 as a yellow air stable solid (150 mg, 0.23
mmol, 19%). Single crystals were obtained from a benzene solution
1
Compound 11. 11 was synthesized according to the general
procedure using CH3CN, n-butyl lithium and di-tert-butylchloro-
phosphine in a 2:1:1 ratio. Acetonitrile (500 µL, 9.52 mmol, 1.0
equiv) reacted with n-butyl lithium (3.00 mL, 4.76 mmol, 0.5 equiv)
and chlorodi-tert-butylphosphine (860 mg, 4.76 mmol, 0.5 equiv)
to form 11 (556 mg, 2.46 mmol, 52%), which was obtained as a
white air stable solid. Single crystals suitable for the X-ray crystal
structure analysis were obtained from a saturated benzene solution
at 5 °C. 1H NMR ([D2]-dichloromethane, 500 MHz, 298 K): δ 4.71
at room temperature. H NMR ([D6]-benzene, 600 MHz, 298 K):
3
δ 3.64 (m, 2H, CH2), 1.55 (d, JPH ) 12.0 Hz, 18H, 4-tBu), 1.39
3
3
(d, JPH ) 14.7 Hz, 18H, 1-tBu), 1.36 (d, JPH ) 10.6 Hz, 18H,
3-tBu), 1.33 (d, 3JPH ) 10.9 Hz, 18H, 6-tBu). 13C{1H} NMR ([D6]-
benzene, 126 MHz, 298 K): δ 204.6 (dddd, JPC ) 40.7 Hz, JPC
)
15.6 Hz, JPC ) 2.7 Hz, JPC ) 0.9 Hz, C3), 179.8 (dddd, JPC ) 43.5
Hz, JPC ) 39.5 Hz, JPC ) 13.0 Hz, JPC ) 2.4 Hz, C5), 106.9 (dddd,
JPC ) 64.9 Hz, JPC ) 36.8 Hz, JPC ) 13.3 Hz, JPC ) 1.8 Hz, C4),
37.1 (d, 1JPC ) 26.0 Hz, 1-tBuq), 36.7 (d, 1JPC ) 22.0 Hz, 6-tBuq),
4
1
34.0 (d, JPC ) 21.5 Hz, 4-tBuq), 32.8 (ddd, JPC ) 31.1 Hz, JPC
)
(br, 1H, CHCN), 4.46 (br, 1H, NH), 2.19 (d, JPH ) 0.8 Hz, 3H,
CdCCH3), 1.10 (d, 3JPH ) 12.2 Hz, 18H, C(CH3)3). 13C{1H} NMR
24.3 Hz, JPC ) 19.9 Hz, CH2), 32.5 (d, JPC ) 26.5 Hz, 3-tBuq),
1
([D2]-dichloromethane, 126 MHz, 298 K): δ 165.0 (d, 2JPC ) 16.5
32.1 (d, 2JPC ) 15.5 Hz, 4-tBuMe), 31.0 (d, 2JPC ) 12.6 Hz, 6-tBuMe),
4
3
30.6 (dd, 2JPC ) 15.0 Hz, JPC ) 1.9 Hz, 3-tBuMe), 28.6 (dd, 2JPC
)
Hz, N-Cd), 121.3 (d, JPC ) 2.1 Hz, CN), 68.6 (d, JPC ) 20.7
1
2
7.5 Hz, JPC ) 1.9 Hz, 1-tBuMe). 31P{1H} NMR ([D6]-benzene, 243
MHz, 298 K): δ 128.8 (s, ν1/2 ) 6.5 Hz, P6), 82.1 (d, JPP ) 2.3
Hz, ν1/2 ) 3.2 Hz, P1), 36.9 (d, JPP ) 3.7 Hz, ν1/2 ) 2.3 Hz, P3),
30.4 (d, JPP2 ) 3.7 Hz, ν1/2 ) 2.4 Hz, P4). Anal. Calcd. for
C36H74N2P4: C, 65.62; H, 11.32; N, 4.25. Found: C, 65.01; H, 11.32;
N, 4.31. MS-ESI-EM Calcd for (C36H74N2P4)H: 659.4875. Found:
659.4872. Melting Point (DSC): 240.8 °C.
Hz, dC(CN)), 34.2 (d, JPC ) 20.7 Hz, C(CH3)3), 28.0 (d, JPC
)
15.4 Hz, C(CH3)3), 21.4 (br, CdCCH3). 31P{1H} NMR ([D2]-
dichloromethane, 81 MHz, 298 K): δ 61.2 (s, ν1/2 ) 19 Hz). Anal.
calcd for C12H23N2P: C, 63.69; H, 10.24; N, 12.38. Found: C, 63.72;
H, 10.24; N, 12.39. IR (ATR): ν˜ 2199 (ν(CtN)). Melting Point
(DSC): 158.4 °C.
X-Ray Crystal Structure Analysis of 11. Formula C12H23N2P,
M ) 226.29, colorless crystal 0.35 × 0.20 × 0.15 mm3, a )
10.9903(2), b ) 12.2569(3), c ) 10.5191(2) Å, V ) 1417.00(5)
Å3, Fcalc ) 1.061 g cm-3, µ) 1.502 mm-1, empirical absorption
correction (0.622 e T e 0.806), Z ) 4, orthorhombic, space group
Cmc21 (No. 36), λ ) 1.54178 Å, T ) 223(2) K, ω and ꢀ scans,
7625 reflections collected ((h, (k, (l), [(sin θ)/λ] ) 0.60 Å-1,
1221 independent (Rint ) 0.047) and 1203 observed reflections [I
g 2 σ(I)], 92 refined parameters, R ) 0.030, wR2 ) 0.077, max.
(min.) residual electron density 0.12 (-0.14) e Å-3, hydrogen atoms
at N1, C3, and C4 from difference Fourier calculations, others
calculated and refined as riding atoms.
X-Ray Crystal Structure Analysis for 6. Formula C36H74N2P4,
M ) 658.85, yellow crystal 0.50 × 0.25 × 0.15 mm3, a )
8.7518(4), b ) 15.1375(5), c ) 15.6376(7) Å, R ) 97.622(2),
)
,
91.057(2), γ ) 97.509(2)°, V ) 2034.4(2) Å3, Fcalc ) 1.076 g cm-3
µ ) 1.883 mm-1, empirical absorption correction (0.453 e T e
0.765), Z ) 2, triclinic, space group P1 bar (No. 2), λ) 1.54178
Å, T ) 223(2) K, ω and ꢀ scans, 23091 reflections collected ((h,
(k, (l), [(sin θ)/λ] ) 0.60 Å-1, 7027 independent (Rint ) 0.038)
and 6747 observed reflections [I g 2 σ(I)], 403 refined parameters,
R ) 0.051, wR2 ) 0.137, max. residual electron density 0.71(-0.56)
e Å-3, hydrogen atoms calculated and refined as riding atoms.
Compound 9b. 9b was synthesized according to the general
procedure using CH3CN, n-butyl lithium and chlorodicyclohexyl-
phosphine) in a 1:1:1 ratio. The reaction of acetonitrile (250 µL,
4.76 mmol, 1.0 equiv), n-butyl lithium (3.00 mL, 4.76 mmol, 1.0
equiv) and chlorodicyclohexylphosphine (1.11 g, 4.76 mmol, 1.0
equiv) gave the pale yellow air sensitive solid 9b (125 mg, 0.20
mmol, 13%). Single crystals suitable for X-ray analysis were
Acknowledgment. Dedicated to Professor Dirk Walther on the
occasion of his 70th birthday. Financial support from the Fonds
der Chemischen Industrie and the Deutsche Forschungsgemeinschaft
is gratefully acknowledged. We thank the BASF for a gift of
solvents.
1
Supporting Information Available: 1D NMR spectra, 2D
NMR experiments, IR data, mass spectroscopic data and
obtained from a toluene solution at room temperature. H NMR
([D6]-benzene, 500 MHz, 298 K): δ 2.25, 1.64 (o-CyPN), 2.14 (i-
9
J. AM. CHEM. SOC. VOL. 131, NO. 49, 2009 17841

A R T I C L E S
Spannhoff et al.
crystallographic data (CIF) of the compounds 1b, 6, 9b and
11. Experimental procedure of the formation of [D2]-6, its 1D
and 2D NMR analysis and its analysis by mass spectrometry.
Experimental procedure of the stoichiometric reaction for the
preparation of 6: formation of the mixture of 6 and 9a and some
characteristic analytic parameters of 9a. Experimental procedure
of the formation of 10 and its 1D NMR data and crystallographic
data. This material is available free of charge via the Internet
at http://pubs.acs.org.
JA905676A
9
17842 J. AM. CHEM. SOC. VOL. 131, NO. 49, 2009