Fumarodinitrile: A versatile reagent in phosphaalkene and arsaalkene chemistry

Article abstract of DOI:10.1021/om010990c

Reaction of equimolar amounts of the ferriophosphaalkene Cp*(CO)₂FeP=C(Ph)NMe₂ (1a) and fumarodinitrile in diethyl ether afforded the ferriophosphetane Cp*(CO)₂FeP-CH(CN)-CH(CN)-C(Ph)NMe₂ (2a). Analogously, Cp*(CO)₂FeP=C(tBu)NMe₂ (1b) was converted into Cp*(CO)₂FeP-CH(CN)-CH(CN)-C(tBu)NMe₂ (2b). Evidence for the cyclic structure of 2a,b in the crystal was provided by the X-ray structural analysis of 2a. Whereas the phosphetane ring of 2b is retained in solution, product 2a in CH₂Cl₂ solution underwent an isomerization to give the acyclic secondary ferriophosphane Cp*(CO)₂Fe-P(H)-CH(CN)-C(CN)=C(Ph)-NMe₂ (3a) as a mixture of isomers. The ferriophosphane Cp*(CO)₂FeP[CH(CN)-CH₂CN]-[CH(CN)-C(CN)=C(tBu)NMe ₂] (5) was isolated in less than 1% yield from the reaction of 1b and the alkene. The reaction of ferrioarsaalkene Cp*(CO)₂FeAs=C(Ph)NMe₂ (6) and fumaronitrile gave rise to the formation of the ferrioarsetane Cp*(CO)₂FeAsCH(CN)-CH-(CN)-C(Ph)NMe₂ (7), which unlike 2a resists ring opening in solution.

Full text of DOI:10.1021/om010990c

1998
Organometallics 2002, 21, 1998-2005
F u m a r od in itr ile: A Ver sa tile Rea gen t in P h osp h a a lk en e
a n d Ar sa a lk en e Ch em istr y
Lothar Weber,* Stefan Kleinebekel, Lars Pumpenmeier,
Hans-Georg Stammler, and Beate Neumann
Fakulta¨t fu¨r Chemie der Universita¨t Bielefeld, Universita¨tsstrasse 25,
D-33615 Bielefeld, Germany
Received November 14, 2001
Reaction of equimolar amounts of the ferriophosphaalkene Cp*(CO)2FePdC(Ph)NMe2 (1a )
and fumarodinitrile in diethyl ether afforded the ferriophosphetane Cp*(CO)2FeP-CH(CN)-
CH(CN)-C(Ph)NMe2 (2a ). Analogously, Cp*(CO)2FePdC(tBu)NMe2 (1b) was converted into
Cp*(CO)2FeP-CH(CN)-CH(CN)-C(tBu)NMe2 (2b). Evidence for the cyclic structure of 2a ,b
in the crystal was provided by the X-ray structural analysis of 2a . Whereas the phosphetane
ring of 2b is retained in solution, product 2a in CH2Cl2 solution underwent an isomerization
to give the acyclic secondary ferriophosphane Cp*(CO)2Fe-P(H)-CH(CN)-C(CN)dC(Ph)-
NMe2 (3a ) as a mixture of isomers. The ferriophosphane Cp*(CO)2FeP[CH(CN)-CH2CN]-
[CH(CN)-C(CN)dC(tBu)NMe2] (5) was isolated in less than 1% yield from the reaction of
1b and the alkene. The reaction of ferrioarsaalkene Cp*(CO)2FeAsdC(Ph)NMe2 (6) and
fumaronitrile gave rise to the formation of the ferrioarsetane Cp*(CO)2FeAsCH(CN)-CH-
(CN)-C(Ph)NMe2 (7), which unlike 2a resists ring opening in solution.
In tr od u ction
vivid evolution of dimethylamine.5 In the 31P NMR
spectra of the reaction mixture there was no evidence
for the hypothetical intermediates IV and V (Scheme
1). Compound Cp*(CO)2FePdC(SiMe3)2 (VIII),6 as a
typical representative of a phosphaalkene with a clas-
sical distribution of electron density, underwent reaction
with II to afford the dark violet ferriophosphane Cp*-
(CO)2Fe-P[CH(SiMe3)2][(Z)-C(CN)dCH(CN)] (IX) as
the result of the formal insertion of the PdC bond into
a C-H bond of the alkene and an (E)/(Z)-isomerization
of the latter.3
In this paper we give an account on the reactivity of
fumarodinitrile toward the ferriophosphaalkenes (E)-
Cp*(CO)2FePdC(Ph)NMe2 (1a )7 and (Z)-Cp*(CO)2FePd
C(tBu)NMe2 (1b)7 and toward the related arsaalkene
(E)-Cp*(CO)2FeAsdC(Ph)NMe2 (6).8
The substitution pattern at a functional group often
influences its electron distribution, imposing changes
to its structure and chemical reactivity. By this, the
synthetic potential of a functionality may be increased
considerably. This is particularly obvious in the chem-
istry of phosphaalkenes, which with alkyl and aryl
substituents exhibit a [σ+π] bond polarity Pδ+dCδ-
about the PdC double bond.1 The π-bond itself is
essentially nonpolar in these species and thus respon-
sible for their alkene-like reactivity in a variety of
cycloadditions. The introduction of one or two amino
substituents at the carbon atom of the PdC double bond
causes an inversion of the distribution of the [σ+π]
electron density as well as of the π-electron density.2
We are interested in the chemical consequences of this
kind of “umpolung”. In the course of our studies on
ferriophosphaalkenes3 and ferrioarsaalkenes4 of the
type Cp*(CO)2Fe-EdCR1R2 (E ) P, As) we tested their
chemical behavior toward electron-deficient alkenes. In
a first study we reacted Cp*(CO)2FePdC(NMe2)2 (I), a
metallophosphaalkene with an inverse π-electron dis-
tribution (Pδ-dCδ+), with fumarodinitrile (II) and di-
methyl fumarate (III), which led to the formation of the
P-metalated 1,2-dihydrophosphetes VI and VII with
Resu lts a n d Discu ssion
Ferriophosphaalkene 1a was combined with an
equimolar amount of fumarodinitrile in diethyl ether
at room temperature. Product 2a separated from the
filtered reaction mixture at 4 °C as orange needles in
77% yield (Scheme 2).
Compound 2a is analogous to the elusive intermediate
IV in the reaction of I with fumarodinitrile. No di-
methylamine elimination to yield 4 was observed from
2a .
(1) Reviews: (a) Appel, R. In. Multiple Bonds and Low Coordination
in Phosphorus Chemistry; Regitz, M., Scherer, O., Eds.; Thieme:
Stuttgart, 1990; pp 157-219. (b) Dillon, K. B., Mathey, F.; Nixon, J .
F. In Phosphorus: The Carbon Copy; Wiley: New York, 1998; pp 88-
127.
(5) Weber, L.; Kaminski, O.; Stammler, H.-G.; Neumann, B.; Ro-
manenko, V. D. Z. Naturforsch. 1993, 48b, 1784-1794.
(6) Gudat, D.; Niecke, E.; Arif, A. M.; Cowley, A. H.; Quashie, S.
Organometallics 1986, 5, 593-595.
(7) Weber, L.; Kleinebekel, S.; Ru¨hlicke, A.; Stammler, H.-G.;
Neumann, B. Eur. J . Inorg. Chem. 200, 1185-1191.
(8) Weber, L.; Kleinebekel, S.; Lo¨nnecke, P. Z. Anorg. Allg. Chem.
2001, 627, 863-868.
(2) Review: Weber, L. Eur. J . Inorg. Chem. 2000, 2425-2441.
(3) Review: Weber, L. Angew. Chem. 1996, 108, 292-310; Angew.
Chem., Int. Ed. Engl. 1996, 35, 271-288.
(4) Review: Weber, L. Chem. Ber. 1996, 129, 367-379.
10.1021/om010990c CCC: $22.00 © 2002 American Chemical Society
Publication on Web 04/04/2002

Fumarodinitrile
Organometallics, Vol. 21, No. 9, 2002 1999
Sch em e 1
Solutions of compound 2a in methylene chloride were
not stable at ambient temperature, and after 24 h of
stirring the metallophosphetane was converted into the
secondary metallophosphane 3a by a ring-opening
process. In keeping with this, the 31P{1H} NMR spec-
trum of a freshly prepared solution of 2a displayed
singlets at δ ) 188.3 and 154.8 in the ratio of 6:3, which
we attribute to two isomers of the four-membered
heterocycle. In the high-field region of the spectrum four
singlets at δ ) -5.2, -4.8, -2.5, and 0.8 in the ratio of
4.5:5:1:1 were observed, which indicate the presence of
four additional components. In the proton-coupled spec-
trum the resonances at δ ) -5.2 and 0.8 appear as
doublets with J PH ) 164.2 and 162.1 Hz, respectively.
The signals at δ ) -4.8 and -2.5 were observed as
doublets of doublets with J PH ) 158.7; 8.8 Hz and 151.7;
7.4 Hz. In contrast to this, the resonance at δ ) 188.3
was split into a doublet with J PH ) 15 Hz, whereas the
singlet at δ ) 154.8 remained unaffected. The size of
the J PH couplings is consistent with a PH bond at a
tricovalent phosphorus atom, as observed in [Cp*-
(CO)2FeP(H)C(Ph)NMe2)]+ (1J PH ) 214.4 Hz).9 A spec-
trum of the same sample of 2a recorded after 24 h
showed the complete disappearance of the two low-field
signals. The rearrangement of the initial product 2a to
the acyclic phosphane 3a was also performed on a
preparative scale.
the PdC function places (Z)-Cp*(CO)2Fe-PdC(tBu)-
NMe2 (1b) (δ31P ) 409.0) in the borderline between
inversely polarized phosphaalkenes such as I (δ31P )
135)5 and classically polarized phosphaalkenes such as
Cp*(CO)2FePdC(SiMe3)2 (VIII) (δ31P ) 641.5).6 The
reaction of 1b and fumarodinitrile furnished the ferrio-
phosphetane 2b as a single isomer. The product was
isolated from diethyl ether at -4 °C as a yellow
microcrystalline solid in 53% yield. From the concen-
trated mother liquor a few crystals of compound 5
separated at 4 °C (yield < 1%) (Scheme 3). Solutions of
product 2b appear to be inert toward ring cleavage at
room temperature.
In the 31P{1H} NMR spectrum of 2b a singlet was
observed at δ ) 165.6, which was not further split in
the 1H-coupled spectrum. Thus, the cycloaddition of
phosphaalkene 1b is accompanied by a strong high-field
shift of ∆δ ) 243.4. The 31P NMR shift of 2a and 2b
may be compared with the resonances of the metalated
P atoms in the P-ferriophosphete VI5 (δ ) 112.8) and
in the P-ferriodiphosphetane 8 (δ ) 128.2).10 To obtain
information on the reactivity of ferrioarsaalkenes to-
ward electron-deficient alkenes, particularly with re-
spect to their phosphorus analogues, ferrioarsaalkene
(E)-Cp*(CO)2FeAsdC(Ph)NMe2 (6)8 was subjected to
reaction with fumarodinitrile under comparable condi-
tions. The only tractable product from this process was
ferrioarsetane 7, which was isolated as orange crystals
As already mentioned in a previous paper, the ab-
sence of a π-conjugation between the Me2N group and
1
in 50% yield. Inspection of the H NMR spectrum of 7
revealed two singlets for the protons of the pentameth-
(9) Weber, L.; Scheffer, M. H.; Stammler, H.-G.; Neumann, B.;
Schoeller, W. W.; Sundermann, A.; Laali, K. Organometallics 1999,
18, 4216-4221.
(10) Weber, L.; Frebel, M.; Boese, R. Chem. Ber. 1990, 123, 733-
738.

2000 Organometallics, Vol. 21, No. 9, 2002
Weber et al.
Sch em e 2
Sch em e 3
ylcyclopentadienyl ring at δ ) 1.72 and 1.85, which is
due to two isomers 7a and 7b in a molar ratio of 2:1
(Scheme 4). In contrast to ferriophosphetane 2a solu-
tions of 7 did not undergo ring-opening reactions. The
molecular structure of the major isomer 7a was deter-
mined by a single-crystal X-ray analysis. Although the
poor quality of the crystals, grown from a diethyl ether
solution at 4 °C, prevented a precise analysis, the
topology of the molecule was revealed beyond any doubt.
Its knowledge is useful for the assignment of the
spectroscopic data.
The molecule may be described as a puckered As-
ferrioarsetane in which the Cp*(CO)2Fe fragment and
F igu r e 1. Formula of 8.

Fumarodinitrile
Organometallics, Vol. 21, No. 9, 2002 2001
Sch em e 4
the phenyl group occupy axial positions in a mutual
trans-orientation. In precursor 6 a cis-disposition of
these units was observed.8
Two axial positions at the ring are occupied by the
two trans-oriented cyano substituents, leaving the
hydrogen atoms in equatorial positions in a mutual
trans-geometry, which well agrees with the coupling
3
constant J HH ) 5.6 Hz between these protons at δ )
3.22 and 4.96 in the major isomer.
F igu r e 2. Proposed structure of 2b.
Singlets at δ ) 1.85 and 2.06 are attributed to the
protons of the Cp* and Me2N units of the major isomer.
In the minor isomer 7b the protons at the four-
membered heterocycle are registered as doublets at δ
) 3.43 and 4.43 (3J HH ) 12.6 Hz). This coupling constant
points to a torsion angle HCCH of nearly 180°, as it is
given in a molecule where both hydrogen atom are
placed axially.
On the grounds of the available data a structural
alternative where the iron complex fragment is equa-
torially linked to the arsenic atom in the minor isomer,
however, cannot be excluded.
The IR spectrum of 7 displays intense ν(CO) bands
at v˜ ) 1992 and 1943 cm-1 and a sharp band of medium
intensity at v˜ ) 2219 cm-1, which is assigned to the
stretching vibration of the cyano group.
For a more detailed discussion of the spectroscopic
and structural features of the (2+2) cycloadducts be-
tween compounds 1a , 1b and fumarodinitrile it seems
appropriate to first consider phosphetane 2b, which was
obtained as a single isomer.
and 2.74 are readily assigned to the protons of the tert-
butyl, Cp*, and NMe2 groups.
In the 13C{1H} NMR spectrum of 2b the tertiary 13C
nuclei of the heterocycle are observed as doublets at δ
) 21.2 (J PC ) 22.6 Hz) and 34.3 (J PC ) 21.5 Hz). A
doublet at δ ) 83.1 (2J PC ) 25.3 Hz) is assigned to the
quaternary carbon atom in R-position to the phosphorus
atom. The cyano groups give rise to doublets at δ )
118.6 (2J PC ) 18.4 Hz) and 121.4 (3J PC ) 13.8 Hz).
Singlets at δ ) 217.1 and 217.7 are caused by the
terminal carbonyl ligands. The IR spectrum of 2b is
dominated by two intense bands at v˜ ) 1993 and 1939
cm-1 for the stretching vibrations of the CO ligands. In
precursor 1b these bands were observed at v˜ ) 1987
and 1940 cm-1. A sharp band of medium intensity at
v˜ ) 2223 cm-1 is due to the ν(CN) mode.
In the 1H NMR spectrum of a freshly prepared
solution of 2a the resonances of both isomers of the four-
membered ring are revealed in addition to those of the
rearranged species 3a . Singlets at δ ) 2.22 and 2.54 in
a ratio of 1:2 are readily assigned to the hydrogen atoms
of the dimethylamino group in both isomers. A doublet
Here a comparison to the structure of ferriophosphe-
tane 8 seems helpful. In the crystal this molecule
displays a puckered four-membered cycle in an all-trans
configuration with the non-hydrogen ligands in equato-
3
of doublets at δ ) 3.91 (2J PH ) 15.1 Hz, J HH ) 8.8 Hz)
and a doublet at δ ) 4.64 (3J HH ) 8.8 Hz) are due to
the trans-oriented ring hydrogen atoms of the major
isomer, whereas the corresponding resonances in the
minor isomer are observed as a pseudo-triplet at δ )
3.42 (J ) 6.1 Hz) and as a doublet at δ ) 4.65 (J ) 6.1
Hz). The molecular structure of the major isomer
confirms these assignments. The IR spectrum of 2a
shows two intense ν(CO) bands at v˜ ) 1998 and 1948
cm-1 and a sharp ν(CN) band of medium intensity at
3
rial dispositions. This situation led to a J HH coupling
for the trans-oriented ring hydrogen atoms of 10.8 Hz.10
Thus, it is reasonable to postulate a similar puckered
four-membered ring structure for 2b with the most
bulky substituents in equatorial sites. In keeping with
this, the ring hydrogen atom in the R-position of the
phosphorus atom is observed as a doublet of doublets
3
2
at δ ) 3.36 with J HH ) 11.7 Hz and J PH ) 4.1 Hz.
The ring proton in the â-position of the heteroatom
v˜ ) 2225 cm-1
.
resonates as a doublet of doublets at δ ) 4.10 (3J PH
)
Orange needles, obtained from the ethereal reaction
mixture at 4 °C, were subjected to an X-ray structure
5.7 Hz; J HH ) 11.7 Hz). Singlets at δ1H ) 0.99, 1.36,
3

2002 Organometallics, Vol. 21, No. 9, 2002
Weber et al.
The P atom is trigonal pyramidal with bond angles
ranging from 73.8(1)° [C(24)-P(1)-C(13)] to 116.4(1)°
[Fe(1)-P(1)-C(13)] (sum of angles ) 302.5°). The en-
docyclic angle C(24)-P(1)-C(13) is significantly com-
pressed in comparison to the endocyclic angles at C(13)
[88.3(2)°], C(23) [97.3(2)°], and C(24) [90.2(2)°]. This
situation is comparable to endocyclic angles in 10 [at
F igu r e 3. Molecular structure of 2a in the crystal (hy-
drogens omitted, 50% probability thermal ellipsoids).
determination. The analysis reveals two independent
molecules in the asymmetric unit. As the bonding
parameters of both molecules do not differ significantly,
the discussion is confined to only one molecule. The
analysis displays the picture of a puckered phosphetane
(torsion angles: C(24)-P(1)-C(13)-C(23) ) 21.4°; P(1)-
C(13)-C(23)-C(24) ) -26.5°; C(13)-P(1)-C(24)-C(23)
) -22.0°; C(13)-C(23)-C(24)-P(1) ) 26.7°) which is
attached to the Cp*(CO)2Fe fragment via an Fe-P
single bond of 2.297(1) Å.
The latter adopts a distorted piano stool configuration
with two nearly linear terminal carbonyl ligands [O(1)-
C(11)-Fe ) 176.4(3)°; O(2)-C(12)-Fe ) 171.0(3)°]. The
most interesting feature of the structure is the geometry
of the organophosphorus ligand. The complex iron group
and the dimethyl amino substituent at the ring are
placed axially in a mutual trans-disposition. Consis-
tently, the phenyl group is cis-oriented to the metal in
an equatorial ring position. A similar stereochemistry
is present in precursor 1a , and these results agree with
the NMR data of the major isomer.
the P atoms 77.2(2)° and 76.9(2)° and at the C atoms
94.2(3)° and 93.9(3)°]. As indicated by the 31P NMR data,
compound 3a was formed as a mixture of four stereo-
1
isomers. In line with the parameters taken from the H-
coupled 31P NMR spectrum it is possible to also analyze
1
the H NMR spectrum of the acyclic phosphanes. The
protons at the phosphorus atom of the major isomers
of 3a are assigned to doublets of doublets at δ ) 2.62
(1J PH ) 164.0, 2J PH ) 5.7 Hz) and δ ) 3.18 (1J PH ) 162.8,
2J PH ) 8.8 Hz). A doublet of doublets at δ ) 3.23 (3J HH
) 5.7, 2J PH ) 3.6 Hz) and a triplet at δ ) 2.68 (|J | ) 8.8
Hz) are due to the protons at the carbon atoms in the
R-position of the P atoms.
We attribute singlets at δ ) 2.88, 2.89, 2.97, and 2.98
to the methyl protons of the amino groups. The protons
at the Cp* rings of the major isomers give rise to singlets
at δ ) 1.66 and 1.75, whereas singlets at δ ) 1.78 and
1.85 are caused by the methyl groups at the ring ligand
of the minor isomers.
The 1,2-dicyanoethylene fragment of the heterocycle
maintained the trans-configuration of the free fumaro-
dinitrile. Interestingly, both cyano groups are located
equatorially with a torsion angle C(22)-C(23)-C(24)-
C(25) ) -81.6°. The iron atom and the cyano group
C(25)-N(3) as well as the amino group and the cyano
unit C(22)-N(2) are in mutual cis-dispositions. The
hydrogen atoms at C(23) and C(24) are axially located,
featuring a torsion angle H(23A)-C(23)-C(24)-H(24A)
of 164.5°. The endocyclic distances C(13)-C(23)
[1.569(4) Å] and C(23)-C(24) [1.526(4) Å] are consistent
with the standard value of a C-C-single bond [1.55 Å].
In contrast to this, the endocyclic PC distances P(1)-
C(24) [1.926(3) Å] and P(1)-C(13) [1.943(4) Å] clearly
exceed the standard value of PC single bonds [1.85 Å].
Such elongated PC bonds are not unusual in four-
membered phosphorus-carbon heterocycles.
The 13C{1H} NMR spectrum of 3a shows doublets at
δ ) 9.3 (3J PC ) 5.7 Hz) and δ ) 9.4 (3J PC ) 8.0 Hz) for
the methyl groups of the Cp* ligands of the major
isomers. The quaternary carbon atoms of the ring ligand
resonate as singlets at δ ) 96.5 and 96.8.
Doublets at δ ) 23.8 (1J PC ) 37.9 Hz), 24.8 (1J PC
)
33.3 Hz), 25.5 (1J PC ) 39.7 Hz), and 26.8 (1J PC ) 32.3
Hz) were due to the carbon atoms in R-position to the P
atom in the two minor and the two major isomers,
respectively. The methyl groups of the amino functions
give rise to singlets at δ ) 42.9 and 43.5 for the major
and the minor isomers, respectively. The cyano-substi-
tuted olefinic carbon atoms of 3a were observed as
doublets at δ ) 78.1 (2J PC ) 11.4 Hz) and δ ) 78.6 (2J PC
) 8.0 Hz), whereas the amino-substituted olefinic
carbon atoms gave rise to singlets at δ ) 161.7 and 162.1
for the major and at δ ) 162.5 and 163.1 for the minor
isomers of 3a . The 13C nuclei of the cyano substituents
were observed in the range δ ) 120.6-122.4.
In 9 the corresponding PC bond length is 1.920(3) Å,5
whereas in 10 and 11 PC distances of 1.918(3),
1.930(3), or 1.931(12)-1.967(12) Å were determined.11
(11) Becker, G.; Becker, W.; Mundt, O. Phosphorus Sulfur 1983, 14,
267-283.

Fumarodinitrile
Organometallics, Vol. 21, No. 9, 2002 2003
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles
(d eg) of 2a in th e Cr ysta l
Fe(1)-C(11)
Fe(1)-C(12)
Fe(1)-P(1)
P(1)-C(24)
P(1)-C(13)
O(1)-C(11)
O(2)-C(12)
N(1)-C(20)
N(1)-C(21)
N(1)-C(13)
N(2)-C(22)
N(3)-C(25)
C(13)-C(14)
C(22)-C(23)
C(23)-C(24)
C(24)-C(25)
1.750(3)
1.769(3)
2.297(1)
1.926(3)
1.943(4)
1.158(4)
1.152(4)
1.463(4)
1.466(4)
1.477(4)
1.142(4)
1.152(4)
1.508(4)
1.488(4)
1.526(4)
1.445(4)
C(11)-Fe(1)-C(12)
C(11)-Fe(1)-P(1)
C(12)-Fe(1)-P(1)
C(24)-P(1)-C(13)
C(24)-P(1)-Fe(1)
C(13)-P(1)-Fe(1)
C(20)-N(1)-C(21)
C(20)-N(1)-C(13)
C(21)-N(1)-C(13)
O(1)-C(11)-Fe(1)
O(2)-C(12)-Fe(1)
N(1)-C(13)-C(14)
N(1)-C(13)-C(23)
C(14)-C(13)-C(23)
N(1)-C(13)-P(1)
C(14)-C(13)-P(1)
C(23)-C(13)-P(1)
N(2)-C(22)-C(23)
C(22)-C(23)-C(24)
C(22)-C(23)-C(13)
C(24)-C(23)-C(13)
C(25)-C(24)-C(23)
C(25)-C(24)-P(1)
C(23)-C(24)-P(1)
N(3)-C(25)-C(24)
94.4(1)
95.4(1)
96.0(1)
F igu r e 4. Molecular structure of 5 in the crystal (hydro-
gens omitted, 50% probability thermal ellipsoids).
73.8(1)
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) of 5 in th e Cr ysta l
112.2(1)
116.4(1)
108.5(2)
119.4(2)
113.9(2)
176.4(3)
171.0(3)
115.4(3)
107.8(2)
114.8(2)
108.4(2)
118.7(2)
88.3(2)
176.1(3)
116.4(2)
117.8(2)
97.3(2)
116.7(3)
121.2(2)
90.2(2)
Fe(1)-C(12)
Fe(1)-C(11)
Fe(1)-P(1)
P(1)-C(13)
P(1)-C(17)
O(1)-C(11)
O(2)-C(12)
N(1)-C(14)
N(2)-C(16)
N(3)-C(18)
N(4)-C(20)
N(5)-C(21)
N(5)-C(23)
N(5)-C(22)
C(13)-C(14)
C(13)-C(15)
C(15)-C(16)
C(17)-C(18)
C(17)-C(19)
C(19)-C(21)
C(19)-C(20)
C(21)-C(24)
1.759(2)
1.759(2)
2.296(1)
1.893(2)
1.921(2)
1.152(2)
1.150(2)
1.145(2)
1.152(3)
1.147(2)
1.149(2)
1.383(2)
1.456(3)
1.458(3)
1.475(3)
1.545(3)
1.464(3)
1.469(2)
1.531(2)
1.380(2)
1.436(2)
1.546(2)
178.3(3)
C(24)-P(1)-C(13)-C(23)
P(1)-C(13)-C(23)-C(24)
C(31)-P(1)-C(24)-C(23)
C(13)-C(23)-C(24)-P(1)
Fe(1)-P(1)-C(13)-N(1)
Fe(1)-P(1)-C(13)-C(14)
Fe(1)-P(1)-C(24)-C(25)
C(14)-C(13)-C(23)-C(22)
N(1)-C(13)-C(23)-C(22)
C(22)-C(23)-C(24)-C(25)
H(23A)-C(23)-C(24)-H(24A)
21.4
-26.5
-22.0
26.7
166.0
31.7
-31.4
87.4
-42.8
-81.6
164.5
C(12)-Fe(1)-C(11)
C(12)-Fe(1)-P(1)
C(11)-Fe(1)-P(1)
C(13)-P(1)-C(17)
C(13)-P(1)-Fe(1)
C(17)-P(1)-Fe(1)
C(21)-N(5)-C(23)
C(21)-N(5)-C(22)
C(23)-N(5)-C(22)
O(1)-C(11)-Fe(1)
O(2)-C(12)-Fe(1)
C(14)-C(13)-C(15)
C(14)-C(13)-P(1)
C(15)-C(13)-P(1)
N(1)-C(14)-C(13)
C(16)-C(15)-C(13)
N(2)-C(16)-C(15)
C(18)-C(17)-C(19)
C(18)-C(17)-P(1)
C(19)-C(17)-P(1)
N(3)-C(18)-C(17)
C(21)-C(19)-C(20)
C(21)-C(19)-C(17)
C(20)-C(19)-C(17)
N(4)-C(20)-C(19)
C(19)-C(21)-N(5)
C(19)-C(21)-C(24)
N(5)-C(21)-C(24)
93.1(1)
97.4(1)
93.8(1)
93.5(1)
112.8(1)
108.7(1)
125.2(2)
121.6(2)
113.2(2)
178.0(2)
174.4(2)
112.2(2)
112.1(1)
108.8(1)
175.0(2)
112.1(2)
177.4(3)
112.4(2)
107.0(1)
112.6(1)
178.4(2)
126.6(2)
121.8(2)
111.6(1)
172.6(2)
117.2(2)
125.0(2)
117.8(1)
The IR spectrum of solid 3a displays two very strong
ν(CO) bands at 1938 and 1991 cm-1 and a strong band
at ν ) 1553 cm-1 for the stretching vibration of the polar
olefinic double bond. Sharp bands of low intensity at
ν ) 2184 and 2222 cm-1 are assigned to the ν(CdN)
stretching vibrations, whereas a weak absorption at ν
) 2364 cm-1 may be due to a ν(PH) mode. Additional
evidence for the acyclic structure of 3a in solution comes
from the X-ray structural analysis of 5, which formally
would result from the insertion of fumarodinitrile into
the PH bond of an acyclic isomer of 2b, although this
molecule could not be detected spectroscopically in the
reaction mixture.
Single crystals of 5 were obtained from diethyl ether
at 4 °C. The analysis (Figure 4, Table 2) displays a
molecule with a distorted piano stool geometry [C(11)-
Fe(1)-P(1) ) 93.8(1)°; C(12)-Fe(1)-P(1) ) 97.4(1)°;
C(11)-Fe(1)-C(12) ) 93.1(1)°] with two nearly linear
carbonyl ligands [Fe(1)-C(11)-O(1) ) 178.0(2)°; Fe(1)-
C(12)-O(2) ) 174.4(2)°]. The most interesting part of

2004 Organometallics, Vol. 21, No. 9, 2002
Weber et al.
Sch em e 5
the molecule is the organophosphorus ligand which is
connected to the metal by an Fe-P single bond of 2.296-
(1) Å. The trigonal pyramidal phosphorus atom (sum of
angles ) 314.9°) is further linked to the two different
organosubstituents by long PC single bonds [P(1)-C(13)
) 1.893(2) Å; P(1)-C(17) ) 1.921(2) Å]. The dimethyl-
amino group and the cyano substituent C(20)-N(4) are
located in a cis-disposition at a long C-C double bond
[C(19)-C(21) (1.380(2) Å; cf. d(CdC) in C2H4 ) 1.353
Å].12 This bond lengthening may be explained by
π-conjugation of the bond pair at the planar nitrogen
atom N(5) (sum of angles ) 360°) into the cyano group.
Accordingly, bond N(5)-C(21) [1.383(2) Å] is shorter
than a single bond between sp2-hybridized N and C
atoms (1.45 Å),13 and bond C(19)-C(20) [1.436(2) Å] is
shorter when compared to the C-C bonds involving the
remaining cyano units of the molecule [C(13)-C(14) )
1.475(3) Å; C(15)-C(16) 1.464(3) Å; C(17)-C(18) )
1.469(2) Å].
transient carbenium ion is efficiently stabilized by the
remaining amino group before deprotonation in the
R-position occurs. Phosphaalkenes and arsaalkenes with
only one amino group at the EdC backbone can no
longer form such amino-stabilized carbenium ions.
Consequently, an R2NH elimination pathway is non-
attractive and heterocycles 2b and 7 are the final
products. Ring cleavage of 2a resulting in the formation
of 3a may be initiated by a proton transfer to the
phosphorus atom to give 2a ′. Ring bending leads to
conformation 2a ′′, where the lone pair at carbon and
the P-C bond to be broken adopt an anti-periplanar
orientation. Conformation 2a ′′ implies an axial ring
position for the phenyl group. With 2b an analogous
conformation 2b′′ with the bulky tert-butyl group in an
axial position as a prerequisite for ring cleavage is
energetically unfavorable and does not occur. One
reason an analogous ring opening is not observed with
heterocycle 7 may be explained by the smaller bond
energy of an AsH bond (245 kJ /mol) versus a PH bond
(322 kJ /mol).14
Con clu sion s
Reaction of fumarodinitrile with ferriophosphaalkenes
and a ferrioarsaalkene featuring different substituents
at the carbon atoms of the PdC bond provides a
convenient access to a variety of novel metalated orga-
nophosphorus and organoarsenic compounds. The present
study has served to get some insight into the complexity
of this two-component reaction.
Ferriophospha- and ferrioarsaalkenes with amino
substituents at the tricoordinate carbon atom and
fumarodinitrile undergo a [2+2] cycloaddition to afford
phosphetanes and arsetanes as the initial products. In
the cases of geminal bis-amino substitution as given in
IV and V (Scheme 1) it is conceivable that the elimina-
tion of dimethylamine is induced by traces of acid. The
Exp er im en ta l Section
All operations were performed under dry, oxygen-free dini-
trogen using standard Schlenk techniques. Solvents were dried
by standard methods and freshly distilled under N2 prior to
use. Infrared spectra were recorded with a Bruker FT-IR
VECTOR 22 spectrometer. 1H, 13C, and 31P NMR spectra were
registered at 22 °C using Bruker AC 100 (1H, 100.13 MHz,
31P, 40.53 MHz) and Bruker AM Avance DRX 500 (1H, 500.13
MHz, 13C, 125.76 MHz, 31P, 200.46 MHz). References: SiMe4
(1H, 13C), 85% H3PO4 (31P).
Elemental analyses were performed at the microanalytical
laboratory of the University of Bielefeld and at Mikroanalytis-
ches Laboratorium H. Kolbe, Mu¨lheim/Ruhr. Compounds Cp*-
(CO)2FePdC(Ph)NMe2 (1a ),7 Cp*(CO)2FePdC(tBu)NMe2 (1b),7
and Cp*(CO)2FeAsdC(Ph)NMe2 (6)8 were synthesized accord-
ing to literature procedures. Fumarodinitrile was purchased
commercially.
(12) Staab, H. A. Einfu¨hrung in die theoretische organische Chemie,
4th ed.; Verlag Chemie: Weinheim, 1966; pp 68-69.
(13) Chernega, A. N.; Ruban, A. V.; Romanenko, V. D.; Markovskii,
L. N.; Korkin, A. A.; Antipin, M. Y.; Struchkov, Y. T. Heteroat. Chem.
1991, 2, 229-241.
(14) Pauling, L. Grundlagen der Chemie, 8th ed.; Verlag Chemie:
Weinheim, 1969; p 795.

Fumarodinitrile
Organometallics, Vol. 21, No. 9, 2002 2005
3
) 18.4 Hz, PCCN), 121.4 (d, J PC ) 13.8 Hz, PCCCN), 217.1
P r ep a r a tion of Com p ou n d s: [Cp *(CO)2F eP CH(CN)-
(s, FeCO), 217.7 (s, FeCO). 31P{1H}NMR (C6D6): δ 165.6s.
Anal. Calcd for C23H32FeN3O2P (469.34): C, 58.86; H, 6.87; N
8.95. Found: C, 58.26; H, 7.10; N 8.83.
CH(CN)C(P h )NMe2] (2a ). At 20 °C a solution of 0.08 g (1.0
mmol) of fumarodinitrile in 10 mL of diethyl ether was added
dropwise to a solution of 1a (0.41 g, 1.0 mmol) in 40 mL of
diethyl ether. After 1 h of stirring the solution was filtered
and the filtrate was stored for 3 days at 4 °C to afford orange
5: δ 31P NMR (C6D6): isomer a: δ 204.9 (2J PH ) 13.8 Hz);
isomer b: 206.3 (2J PH ) 13.8 Hz); 5a :5b ) 10:1. Due to the
small amount of material, no further spectra or elemental
analyses could be provided.
needles of product 2a (yield: 0.38 g, 77%). IR (KBr, cm-1
)
1
ν: 2224 (m, CN), 1997 (vs, FeCO), 1947 (vs, FeCO). H NMR
(C6D6): δ 1.67 (s, 15H, C5(CH3)5), 2.22s and 2.54 (s, 6H,
N(CH3)3), 3.42 (“t”, J ) 6.1 Hz) and 3.91 (dd, J ) 15.1, 8.8 Hz,
1H, PCH), 4.64 (d, J ) 8.8 Hz) and 4.65 (d, J ) 6.1 Hz, 1H,
Cp *(CO)2F eAsCH (CN)CH (CN)C(P h )NMe2 (7). Analo-
gously to the preparation of 2a 0.21 g (50%) of orange
crystalline 7 was obtained from the reaction of 0.37 g (0.8
mmol) of 6 and 0.06 g (0.8 mmol) of fumarodinitrile in 35 mL
of diethyl ether. IR (KBr, cm-1): ν 2219 (m, CN), 1992 (vs,
PCCH), 7.08-7.50 (m, 5H, Ph). 31P{1H} NMR (CD2Cl2):
δ
154.8 (s, minor isomer), 188.3 (s, major isomer). MS/ESI(+):
m/z 490 (MH+), 462 (MH+ - CO), 434 (MH+ - 2CO). Anal.
Calcd for C25H28FeN3O2P(489.34): C, 61.36; H, 5.77; N, 8.58.
Found: C, 61.34; H, 5.84; N, 8.39.
1
FeCO), 1943 (vs, FeCO). H NMR (C6D6): δ 1.72s and 1.85 (s,
3
15H, C5(CH3)5), 2.06s and 2.46 (s, 6H, N(CH3)2), 3.22 (d, J HH
3
) 5.6 Hz) and 3.43 (d, J HH ) 12.6 Hz, 1H, AsCH), 4.43 (d,
3J HH ) 12.6 Hz) and 4.96 (d, 3J HH ) 5.6 Hz, 1H, AsCCH), 7.20-
7.64 (m, 5H, H-Ph). 13C{1H}NMR (CD2Cl2): δ. 7.9 (s, AsCH),
9.3 (s, C5(CH3)5), 39.4 (s,AsC-C), 43.0 (s, N(CH3)2), 65.6 (s,
AsCN), 97.4 (s, C5(CH3)5), 121.3 (s, CN), 122.9 (s, CN), 122.95s,
125.9s, and 128.5 (s, C-Ph), 141.5 (s, i-C-Ph), 214.9 (s, FeCO),
217.5 (s, FeCO). Anal. Calcd for C25H28AsFeN3O2 (533.28): C,
56.31; H, 5.29, N, 7.88. Found: C, 56.34, H, 5.36, N, 7.73.
Cp *(CO)2F eP H-CH(CN)-C(CN)dC(P h )NMe2 (3a ). A
solution of freshly prepared 2a (0.38 g, 0.8 mmol) in 20 mL of
methylene chloride was stirred at ambient temperature for 24
h. At that time in the 31P{1H} NMR spectrum of the mixture
the signals of 2a had completely disappeared. Solvent and
volatile components were removed in vacuo to give quantita-
tively 3a as a light yellow solid. IR (KBr, cm-1): ν 2364 (w,
PH), 2222 (w-m, CN), 2184 (m, CN), 1991 (vs, FeCO), 1938
X-r a y Str u ctu r a l An a lysis of 2a . Single crystals of 2a
were grown from diethyl ether at 4 °C. An orange crystal of
the approximate dimensions of 0.28 × 0.12 × 0.06 mm was
measured on a Nonius Kappa CCD system with Mo KR
radiation (λ ) 0.71073 Å) at 100 K. Crystal data and refine-
ment details: space group Pca21, cell dimensions a ) 16.4240-
(2) Å, b ) 14.0020(2) Å, c ) 20.2780(3) Å, V ) 4663.31(11) Å3
(refined from 5773 reflections), Z ) 8, dcalcd ) 1.394 g cm-3, µ
) 0.743 mm-1, absorption correction: multiscan max/min
transmission 0.9568/0.8190. Structure solution and refinement
on F2 with SHELXS-97 and SHELXL-97, 50 786 intensities
collected, 10 126 unique (Rint ) 0.046) and 9073 with I > 2σ(I),
1
(vs, FeCO), 1553 (s, CdC). H NMR (CD2Cl2): δ 1.66s, 1.75s,
1.78s, and 1.85 (s, 15H, C5(CH3)5); 2.62 (dd, 1J PH ) 164.0, 2J PH
1
) 5.7 Hz) and 3.18 (dd, J PH ) 8.8 Hz, 1H, PH), 2.88s, 2.89s,
2.97s, and 2.89 (s, 6H, N(CH3)2), 2.68 (“d”, |J | ) 8.8 Hz and
2
3.23 (dd,3J HH ) 5.7, J PH ) 3.6 Hz, 1H, PCH), 7.29-7.47 (m,
3
5H, Ph-H). 13C{1H} NMR (CD2Cl2): δ 9.3 (d, J PC ) 5.7 Hz),
3
1
9.4 (d, J PC ) 8.0 Hz), 9.5s, 9.6(s, C5(CH3)5), 23.8 (d, J PC
)
)
1
1
37.9 Hz, PCH), 24.8 (d, J PC ) 33.3 Hz, PCH), 25.5 (d, J PC
40.2 Hz, PCH), 26.8 (d, J PC ) 32.3 Hz, PCH), 42.9s and 43.5
1
2
2
(s, N(CH3)2), 78.1 (d, J PC ) 11.4 Hz, CdC-CN) 78.6 (d, J PC
) 8.0 Hz, CdC-CN); 120.7 (d, 2J PC ) 20.7 Hz, PCHCN), 121.2
(d, 2J PC ) 19.9 Hz, PCHCN), 121.8 (d, 2J PC ) 20.7 Hz, PCHCN)
122.0s and 122.4s (CdC-CN); 128.9, 129.3, 129.4, 130.3, 130.4,
130.8 (C-Ph), 135.2s, 135.4s, 136.2s, 136.3 (s, i-C-Ph), 161.7s,
162.1s, 162.5s, and 163.1 (s, CdC-CN), 215.8, 216.0, 216.3,
216.7, 216.8, 216.9 (FeCO). 31P NMR (CD2Cl2): δ -5.2 (d, 1J PH
578 parameters, hydrogen atoms treated as riding groups,
2
R-indices for reflections with I > 2σ(I): RF ) 0.0376; wRF
)
0.0917, GooF(F2) ) 1.060, maximum/minimum residual densi-
ties 0.986 and -0.588 e Å-3
.
X-r a y Str u ctu r a l An a lysis of 5. Single crystals of 5 were
grown from diethyl ether at 4 °C. A yellow crystal of the
approximate dimensions of 1.20 × 0.80 × 0.06 mm was
measured on a Nonius Kappa CCD system with Mo KR
radiation (λ ) 0.71073 Å) at 100 K. Crystal data and refine-
ment details: space group P1h, all dimensions a ) 9.8590(1)
Å, b ) 9.8900(1) Å, c ) 14.3870(2) Å, R ) 76.2420(5)°, â )
89.5180(5)°, γ ) 86.3360(6)°, V ) 1359.75(3) Å3 (refined from
1
2
) 164.2 Hz, PH), -4.8(dd, J PH ) 158.7, J PH ) 8.8 Hz, PH),
1
2
1
-2.5 (dd, J PH ) 151.7 Hz, J PH ) 7.4 Hz, PH), 0.8 (d, J PH
)
162.1 Hz, PH). MS/ESI (+): m/z 490 (MH+), 462 (MH+ - CO),
434 (MH+ - 2CO). Anal. Calcd for C25H28FeN3O2P (489.34):
C, 61.36; H, 5.77; N, 8.58. Found: C, 61.44; H, 5.71; N, 8.46.
Cp *(CO)2F eP -CH (CN)CH (CN)C(tBu )NMe2 (2b ) a n d
Cp *(CO)2F eP [CH(CN)-CH2CN][CH(CN)-C(CN)dC(tBu )-
NMe2] (5). A solution of fumarodinitrile (0.05 g, 0.6 mmol) in
10 mL of diethyl ether was added dropwise to a chilled solution
(-40 °C) of 1b in 30 mL of diethyl ether. It was warmed to
ambient temperature and stirred for 24 h. Solvent and volatile
components were removed in a vacuum, and the residue was
triturated with 20 mL of diethyl ether. It was filtered, and
the filter cake was washed with diethyl ether (4 × 5 mL). The
filtrate was concentrated to ca. 20 mL and stored at 4 °C,
whereupon 2b (0.15 g, 53%) separated as a yellow powder.
After filtration the mother liquor was concentrated to 10 mL
and stored at 4 °C to afford a small amount of a yellow
precipitate, consisting of 2b and 5. Upon recrystallization from
diethyl ether, a few yellow needles (yield < 1%) of 5 were
obtained. 2b: IR (KBr, cm-1): ν 2223 (m, CN), 1993 (vs, FeCO),
1939 (vs, FeCO). 1H NMR (C6D6): δ 0.99 (s, 9H, C(CH3)3), 1.36
(s, 15H, C5(CH3)5), 2.74 (s, 6H, N(CH3)2), 3.36 (dd, 3J HH ) 11.7,
2J PH ) 4.1 Hz, 1H, PCH), 4.10 (dd, 3J HH ) 11.7, 3J PH ) 5.7 Hz,
1H, PCCH). 13C{1H} NMR (C6D6): δ 8.9s, C5(CH3)5), 21.2 (d,
6204 reflections), Z ) 2, dcalcd ) 1.337 g cm-3, µ ) 0.646 mm-1
,
absorption correction: multiscan max/min transmission 0.9622/
0.5109. Structure solution and refinement on F2 with SHELXS-
97 and SHELXL-97, 44 023 intensities collected, 6210 unique
(R(int) ) 0.045) and 5014 with I > 2σ(I), 348 parameters,
hydrogen atoms treated as riding groups, R-indices for reflec-
tions with I > 2σ(I): RF ) 0.0338; wRF ) 0.0793, GooF(F2) )
2
1.021, maximum/minimum residual electron densities 0.413
and -0.581 e Å-3
.
Ack n ow led gm en t. Financial support was provided
by DFG and the Fonds der Chemischen Industrie, which
is gratefully acknowledged.
Su p p or tin g In for m a tion Ava ila ble: Tables of X-ray
data, atomic coordinates, thermal parameters, complete bond
lengths and angles, and thermal ellipsoid plots for compounds
3a and 5. This material is available free of change via the
Internet at http://pubs.acs.org.
3
1J PC ) 22.6 Hz, PCH), 29.8 (d, J PC ) 8.0 Hz, C(CH3)3), 34.3
2
2
(d, J PC ) 21.5 Hz, PCCH), 42.4 (d, J PC ) 18.1 Hz, C(CH3)3),
45.0 (s, N(CH3)2), 83.1 (d, |J PC| ) 25.3 Hz, PCN), 118.6 (d, 2J PC
OM010990C