Synthesis of racemic aminoalkylferrocenyldichlorophosphanes and -dialkylphosphonites and their conversion to primary phosphanes

Article abstract of DOI:10.1021/om1004012

The dichlorophosphanyl-substituted ferrocene complexes 1- dichlorophosphanyl-2-N,N-dimethylaminomethyl-3-diphenylphosphanylferrocene (2a) and 1-dichlorophosphanyl-2-N,N-dimethylaminomethyl-3,1′- bis(diphenylphosphanyl)ferrocene (2b) have been prepared by the reaction of phosphorus trichloride with the corresponding lithiated aminoalkylferrocene precursors. The crystal structure of 2a reveals a short N...P distance, which is suggestive of a weak N→P dative bond. Using diethyl chlorophosphite instead of phosphorus trichloride as electrophile gave 1-diethoxyphosphanyl-2-N,N-dimethylaminomethyl-3-diphenylphosphanylferrocene (3a) and 1-diethoxyphosphanyl-2-N,N-dimethylaminomethyl-3,1′- bis(diphenylphosphanyl)ferrocene (3b), respectively. The latter was converted to the corresponding dimethoxy compound 4b by reaction with methanol. Crystal structures of 3 and 4b have been determined. Reduction of 2, 3, and 4b with LiAlH₄ or LiAlH₄/SiMe₃Cl yielded the primary phosphanes 1-diphenylphosphanyl-2-N,N-dimethylaminomethyl-3-phosphanylferrocene (5a) and 1,1′-bis(diphenylphosphanyl)-2-N,N-dimethylaminomethyl-3- phosphanylferrocene (5b). The latter was also structurally characterized by X-ray diffraction.

Full text of DOI:10.1021/om1004012

Organometallics 2010, 29, 5427–5434 5427
DOI: 10.1021/om1004012
Synthesis of Racemic Aminoalkylferrocenyldichlorophosphanes
and -dialkylphosphonites and Their Conversion to Primary Phosphanes†
†
†
Carolin Limburg, Peter Lonnecke, Santiago Gomez-Ruiz,†,‡ and
€
ꢀ
Evamarie Hey-Hawkins*,†
†
€
Institut fu€r Anorganische Chemie der Universitat Leipzig, Johannisallee 29, D-04103 Leipzig,
‡
Germany, and Departamento de Quımica Inorganica y Analıtica, ESCET, Universidad Rey Juan Carlos,
´
28933 Moꢀstoles, Madrid, Spain
ꢀ
´
Received May 1, 2010
The dichlorophosphanyl-substituted ferrocene complexes 1-dichlorophosphanyl-2-N,N-dimethylami-
nomethyl-3-diphenylphosphanylferrocene (2a) and 1-dichlorophosphanyl-2-N,N-dimethylaminomethyl-
3,10-bis(diphenylphosphanyl)ferrocene (2b) have been prepared by the reaction of phosphorus trichloride
with the corresponding lithiated aminoalkylferrocene precursors. The crystal structure of 2a reveals a short
N
Pdistance, whichissuggestive of a weak NfP dative bond. Using diethyl chlorophosphite instead of
3 3 3
phosphorus trichloride as electrophile gave 1-diethoxyphosphanyl-2-N,N-dimethylaminomethyl-3-diphe-
nylphosphanylferrocene (3a) and 1-diethoxyphosphanyl-2-N,N-dimethylaminomethyl-3,10-bis(diphenyl-
phosphanyl)ferrocene (3b), respectively. The latter was converted to the corresponding dimethoxy
compound 4b by reaction with methanol. Crystal structures of 3 and 4b have been determined. Reduction
of 2, 3, and 4b with LiAlH4 or LiAlH4/SiMe3Cl yielded the primary phosphanes 1-diphenylphosphanyl-2-
N,N-dimethylaminomethyl-3-phosphanylferrocene (5a) and 1,10-bis(diphenylphosphanyl)-2-N,N-di-
methylaminomethyl-3-phosphanylferrocene (5b). The latter was also structurally characterized
by X-ray diffraction.
Introduction
planar chirality, for which racemization is virtually impos-
sible.5 The number of such planar-chiral phosphanylferro-
cenes has been growing ever since,6 as has the number of
applications of these complexes as ligands in asymmetric
reactions such as hydrogenation, Grignard reactions, hydro-
silylations, and aldol reactions.2-4,7 Considering the large
amount of information published concerning the chemistry
of phosphane ligands containing ferrocenyl moieties, it is
surprising that only very little is known about primary
ferrocenyl-substituted phosphanes.
Primary phosphanes have generally a very rich chemistry
accessible through the reactivity of the P-H bonds.8 Reac-
tions with unsaturated systems, carbonyl groups, Michael
acceptors, alkyl and aryl halides, halogens, alkali metals, and
Lewis acids are well known and provide many possibilities to
produce functionalized secondary or tertiary phosphanes,
which may even contain chiral phosphorus centers.9 Owing
to the reactive character of the P-H bonds, preparation of
primary phosphanes with ferrocenyl groups incorporated
into the molecule would provide a useful means for further
Since the first synthesis of 1,10-bis(diphenylphosphanyl)-
ferrocene (DPPF),1 ferrocene has proved to be a versatile
substituent for phosphanes because of its rich chemistry,
stability, and redox properties.2 Ferrocenylphosphanes
attract constant attention for their coordination chemistry,
with significant recent emphasis on the application of chiral
ferrocenylphosphane metal complexes in asymmetric homo-
geneous catalysis. The first chiral phosphanylferrocene com-
plex, (R)-N,N-dimethyl-1-[(S)-2-(diphenylphosphanyl)ferro-
cenyl]ethylamine ((R,S)-PPFA), was prepared by Hayashi
et al. in 19743 and was successfully applied in homogeneous
catalysis only two years later.4 Henceforward, 1,2-disubsti-
tuted phosphanylferrocenes have been of special interest in
organometallic and coordination chemistry because of their
† Part of the Dietmar Seyferth Festschrift.
*To whom correspondence should be addressed. E-mail: hey@rz.uni-
leipzig.de.
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r
2010 American Chemical Society
Published on Web 08/03/2010
pubs.acs.org/Organometallics

5428 Organometallics, Vol. 29, No. 21, 2010
Limburg et al.
Scheme 1
formation of other ferrocene-containing compounds. How-
ever, primary phosphanes in which a ferrocene unit is directly
attached to the phosphorus atom are not well investigated,
possibly because in most reported cases the compounds were
highly air sensitive and could only be handled in an inert
atmosphere. In addition to the known phosphanylferrocene10
and 1,10-bis(phosphanyl)ferrocene,11 we recently reported the
synthesis of planar-chiral primary aminoalkylphosphanylferro-
cenes by reduction of the corresponding ferrocenylphos-
phonates12 or ferrocenyldichlorophosphanes.13
phosphanyl)ferrocenyl]ethylamine (BPPFA),14 as well as the
versatile synthetic possibilities offered by reactivity of P-H
bonds, we were interested in including a primary phosphanyl
group in well-known planar-chiral ferrocenylphosphanes for
the following preparation of alkali-metal ferrocenylphospha-
nides, which may be suitable precursors for the synthesis of
novel phosphines15,16 or transition-metal phosphanides, which
are known to exhibit versatile reactivity.17
As a first step in the attainment of this goal, we herein
report the facile and convenient synthesis of the novel
racemic primary phosphanes 1-diphenylphosphanyl-2-
N,N-dimethylaminomethyl-3-phosphanylferrocene (5a)
and 1,10-bis(diphenylphosphanyl)-2-N,N-dimethylamino-
methyl-3-phosphanylferrocene (5b). The preparation of
the corresponding ferrocenyldichlorophosphanes (2) and
-dialkylphosphonites (3 and 4b), which are the key inter-
mediates in the synthesis of the primary phosphanes, is
also described.
With regard to the numerous applications of compounds
such as N,N-dimethyl-1-[2-(diphenylphosphanyl)ferrocenyl]-
ethylamine (PPFA)3 and N,N-dimethyl-1-[10,2-bis(diphenyl-
(8) For an overview see: (a) Phosphorus: An Outline of its Chemistry,
Biochemistry and Technology, 4th ed.; Corbridge, D. E. C., Ed.; Elsevier:
New York, 1990. (b) The Chemistry of Organophosphorus Compounds;
Hartley, F. R., Eds.; John Wiley & Sons: Chichester, 1994. (c) Organic
Phosphorus Compounds; Kosolapoff, G. M.; Maier, L., Eds.; John Wiley &
Sons: New York, 1972. (d) Maier, L. Prog. Inorg. Chem. 1963, 5, 27.
(e) Hey-Hawkins, E.; Karasik, A. A. Product Class 4: Alkylphosphines. In
Science of Synthesis, Houben-Weyl Methods of Molecular Transforma-
tions, Category 5: Compounds with One Saturated Carbon-Heteroatom
Bond, Series Vol. 42, Organophosphorus Compounds (incl. RO-P and
RN-P); Mathey, F., Ed.; Thieme: New York, 2009; Chapter 42.4,
pp 71-108. (f) Hey-Hawkins, E.; Karasik, A. A. Product Class 5: Bis-
(alkylphosphino)- and Poly(alkylphosphino)alkanes, and Di- and Polypho-
sphines with a P-P Bond. In Science of Synthesis, Houben-Weyl Methods of
Molecular Transformations,Category 5: Compounds with One Saturated
Carbon-Heteroatom Bond, Series Vol. 42, Organophosphorus Com-
pounds (incl. RO-P and RN-P); Mathey, F., Ed.; Thieme: New York,
2009; Chapter 42.5, pp 109-154.
(9) For selected examples see: (a) Dorn, H.; Singh, R. A.; Massey,
J. A.; Lough, A. J.; Manners, I. Angew. Chem., Int. Ed. 1999, 38, 3321.
(b) Termaten, A. T.; Nijbacker, T.; Schakel, M.; Lutz, M.; Spek, A. L.;
Lammertsma, K. Chem. - Eur. J. 2003, 9, 2200. (c) Gali, H.; Prabhu, K. R.;
Karra, S. R.; Katti, K. V. J. Org. Chem. 2000, 65, 676. (d) Brauer, D. J.;
Hingst, M.; Kottsieper, K. W.; Liek, C.; Nickel, T.; Tepper, M.; Stelzer, O.;
Sheldrick, W. S. J. Organomet. Chem. 2002, 645, 14. (e) Kagan, H. B.; Diter,
P.; Gref, A.; Guillaneux, D.; Masson-Szymczak, A.; Rebiere, F.; Riant, O.;
Samuel, O.; Taudien, S. Pure Appl. Chem. 1996, 68, 29. (f) Felsberg, R.;
Blaurock, S.; Junk, P. C.; Kirmse, R.; Voigt, A.; Hey-Hawkins, E. Z. Anorg.
Allg. Chem. 2004, 630, 806.
Results and Discussion
Readily available aminoalkylferrocenyldiphenylphosphanes
(1)13,18 were used as starting materials for the synthesis of the
desired primary ferrocenylphosphanes 5. Suitable precursors
containing a PX2 group, which can be converted into a PH2
group, needed to be prepared first. As shown in Scheme 1,
(14) Hayashi, T.; Mise, T.; Fukushima, M.; Kagotani, M.; Nagashima,
N.; Hamada, Y.; Matsumoto, A.; Kawakami, S.; Konishi, M.; Yama-
moto, K.; Kumada, M. Bull. Chem. Soc. Jpn. 1980, 53, 1138.
(15) (a) Fritz, G.; Scheer, P. Chem. Rev. 2000, 100, 3341. (b) Organo-
phosphorus Chemistry; Royal Society of Chemistry: Cambridge,
1970-2006; Vols. 1-35. (c) Trifimov, B. A.; Arbuzova, S. N.; Gusarova,
N. K. Russ. Chem. Rev. 1999, 68, 215. (d) Issleib, K. Z. Chem. 1962, 2, 163.
(e) Pauer, F.; Power, P. P. In Lithium Chemistry: A Theoretical and
ꢀ
Experimental Overview; Sapse, A.-M.; von Rague Schleyer, P., Eds.; John
Wiley & Sons: New York, 1994; Chapter 9, p 361-373.
(16) For selected examples see: (a) Issleib, K.; Tzschach, A. Chem.
Ber. 1959, 92, 1397. (b) Abicht, H. P.; Issleib, K. Z. Chem. 1985, 25, 150.
(c) Issleib, K.; von Malotki, P. Phosphorus, Sulfur, Silicon 1973, 3, 141.
(d) Lischewski, M.; Issleib, K.; Tille, H. J. Organomet. Chem. 1973, 54, 195.
(e) Issleib, K.; Haftendorn, M. Z. Anorg. Allg. Chem. 1970, 376, 79.
(17) (a) Stephan, D. W. Angew. Chem., Int. Ed. 2000, 39, 314.
(10) Spang, C.; Edelmann, F. T.; Noltemeyer, M.; Roesky, H. W.
Chem. Ber. 1989, 122, 1247.
(11) Burk, M. J.; Gross, M. F. Tetrahedron Lett. 1994, 35, 9363.
€
(12) Tschirschwitz, S.; Lonnecke, P.; Reinhold, J.; Hey-Hawkins, E.
€
(b) Issleib, K.; Frohlich, H. O.; Wenschuh, E. Chem. Ber. 1962, 95, 2742.
Angew. Chem., Int. Ed. 2005, 44, 2965.
€
(13) Tschirschwitz, S.; Lonnecke, P.; Hey-Hawkins, E. Dalton Trans.
€
(c) Issleib, K.; Frohlich, H. O. Chem. Ber. 1962, 95, 375.
2007, 1377.
(18) Marr, G.; Hunt, T. J. Chem. Soc., C 1969, 1070.

Article
Organometallics, Vol. 29, No. 21, 2010 5429
racemic 1-diphenylphosphanyl-2-N,N-dimethylaminomethyl-
ferrocene (1a) and racemic 1,10-bis(diphenylphosphanyl)-2-
N,N-dimethylaminomethylferrocene (1b) were further functio-
nalized by ortho-selective lithiation and subsequent treatment
with an electrophile.
Synthesis of Dichlorophosphanes 2a and 2b. The dichloro-
phosphanes 2 were prepared by reaction of the monolithiated
species with a slight excess of PCl3 at low temperature. The
resulting compounds are stable in the solid state, but decom-
pose in solution. In general, aminoalkylferrocenyldichloropho-
sphanes decompose in all common solvents. They are slightly
more stable in chlorinated or aromatic solvents, whereas in
nonpolar solvents such as n-hexane decomposition occurs
rapidly.13 Despite intense efforts, we were not able to purify
2b by crystallization due to its fast decomposition even in
CH2Cl2. Therefore, 2b could be verified only as a crude product
by 31P{1H} NMR spectroscopy (δP = -21.2, -24.1, and 137.7
ppm). However, racemic 2a was isolated by crystallization in a
66% yield and was consequently characterized by common
analytical techniques. The 31P{1H} NMR spectra exhibit reso-
nances of the diphenylphosphanyl and the dichlorophosphanyl
group in the expected range (δP = -23.0 and 138.3 ppm). A
significant feature that is well known for ferrocenyldichlorophos-
Figure 1. Molecular structure of 2a (only the S enantiomer is
shown) with thermal ellipsoids at the 50% probability level. H
˚
atoms have been omitted for clarity. Selected bond lengths (A)
and angles (deg): P1-Cl1 2.1224(9), P1-Cl2 2.0922(8), P1-C1
1.799(2), P2-C3 1.818(2), P1 N1 2.680(2), C1-P1-Cl1
3 3 3
96.76(7), C1-P1-Cl2 100.94(8), Cl1-P1-Cl2 95.68(4).
Synthesis of Diethylphosphonites 3 and Dimethylphospho-
nite 4b. In a similar procedure to the synthesis of 2, diethyl-
phosphonites 3 can be prepared by treatment of the mono-
lithiated ferrocenyl species with diethyl chlorophosphite.
The resulting diethylphosphonites are stable in solution and
in the solid state, which makes them much more convenient
to handle than the dichloro-substituted compounds. Hence,
racemic 3 could be isolated with better yields than the corre-
sponding dichlorophosphanes (3a: 82%; 3b: 68%). Treating
3bwith an excess of methanol leads to quantitative exchange of
the ethoxyl groups and formation of racemic compound 4b.
In the 31P{1H} NMR spectra the resonances of the di-
phenylphosphanyl groups [δP = -23.9 (3a); -24.4 and
-18.7 (3b); -24.5 and -18.8 ppm (4b)] and of the dialkyl-
phosphonite groups [δP = 158.4 (3a); 157.2 (3b); 162.9 ppm
(4b)] appear in the expected range. Due to the less electro-
phane complexes13,19 is the exceptionally large 1JCPCl coupling
2
constant, in this case 66.9 Hz, which can be observed in the
13C{1H} NMR spectrum. It is caused by the electronegativity of
the chlorine substituents and the resultant enhanced s character
of the hybrid orbitals of the phosphorus atom directed toward
the cyclopentadienyl ring.20
The molecular structure of 2a is depicted in Figure 1. The
geometrical environment of both phosphorus atoms is dis-
torted tetrahedral. Bending of the dimethylaminomethyl group
toward the PCl2 group indicates a weak NfP dative bond,
similar to that observed for 1-dichlorophosphanyl-2-N,N-
dimethylaminomethylferrocene.13 The N P1 distance of
3 3 3
˚
2.680(2) A, which is a little longer than that reported for the
above example, but rather short in comparison to those
reported for tertiary aminomethylarylphosphanes,21 verifies
the existence of such an interaction. The P-Cl bonds
negative character of the alkoxyl substituents compared
1
to the chloro substituents, the JCP(OR) coupling constant
2
[23.4 (3a), 23.8 (3b), and 25.4 Hz (4b)] is significantly smaller
than 1JCPCl observed for 2b.
˚
[P1-Cl1 2.1224(9), P1-Cl2 2.0922(8) A] are longer than in
2
structurally characterized aryldichlorophosphanes22 and 1,10-
The molecular structures of the dialkylphosphonites are
shown in Figure 2; selected bond lengths and angles are given
in Table 1. As for the dichlorophosphanyl compound, the
geometrical environment of all phosphorus atoms is dis-
torted tetrahedral. The dimethylaminomethyl group faces
toward the phosphonite group in 3a, whereas in the 1,10-
bis(diphenyl)phosphanyl-substituted compounds it faces
bis(dichlorophosphanyl)ferrocene,19,23 which in general lie be-
˚
tween 2.05 and 2.08 A. The unusually long P1-Cl1 bond (trans
to the weak NfP dative bond) is also indicative of a dative
interaction between P and N and in accordance with compar-
able compounds.13,24 The weak dative bond is not retained in
1
solution, as H NMR measurements at room temperature
show only one singlet for the two methyl groups attached to
the nitrogen atom.
toward the diphenylphosphanyl group. Even though the
˚
N P1 distance of 3a of 3.158(1) A is significantly longer
than that of 2a, it is still smaller than the sum of the van der
3 3 3
Waals radii of 3.40 A.25 Hence, the presence of a weak NfP
(19) Moser, C.; Orthaber, A.; Nieger, M.; Belaj, F.; Pietschnig, R.
Dalton Trans. 2006, 3879.
˚
(20) (a) NMR-Spektroskopie von Nichtmetallen, Band 3: 31P-NMR-
Spektroskopie; Berger, S.; Braun, S.; Kalinowski, H.-O., Eds.; Thieme:
Stuttgart, 1993. (b) 13C-NMR-Spektroskopie; Kalinowski, H.-O.; Berger,
S.; Braun, S., Eds.; Thieme: Stuttgart, 1984. (c) Bent, H. A. Chem. Rev. 1961,
61, 275.
dative bond can be assumed. For the cyclic amino phospho-
nite PhP(μ-OC6H2-2,4-Me2-6-CH2)2NMe such an interac-
26
˚
tion is described for a N P1 distance of 3.152(3) A.
3 3 3
However, the P-O bond lengths are in the same range
as in other reported aromatic phosphonites and do not
verify the presence of a NfP dative interaction.26,27 Steric
ꢀ
(21) Chuit, C.; Corriu, R. J. P.; Monforte, P.; Reye, C.; Declercq,
J. P.; Dubourg, A. Angew. Chem., Int. Ed. 1993, 32, 1430.
(22) (a) Wehmschulte, R. J.; Khan, M. A.; Hossain, S. I. Inorg. Chem.
2001, 40, 2756. (b) Kilian, P.; Slawin, A. M. Z.; Woollins, J. D. Chem.-Eur.
J. 2003, 9, 215. (c) Reiter, S. A.; Nogai, S. D.; Schmidbaur, H. Dalton Trans.
2005, 247.
(25) Bondi, A. J. Phys. Chem. 1964, 68, 441.
(26) Timosheva, N. V.; Chandrasekaran, A.; Day, R. O.; Holmes,
(23) Niecke, E.; Nieger, M.; Pietschnig, R. Phosphorus, Sulfur, Silicon
R. R. Inorg. Chem. 1998, 37, 4945.
1999, 147, 325.
(27) (a) Cowley, A. H.; Pakulski, M.; Norman, N. C. Polyhedron
1987, 6, 915. (b) Kottsieper, K. W.; K€uhner, U.; Stelzer, O. Tetrahedron:
Asymmetry 2001, 12, 1159. (c) Kilian, P.; Slawin, A. M. Z.; Woollins, J. D.
Dalton Trans. 2003, 3876.
(24) van den Ancker, T. R.; Andrews, P. C.; King, S. J.; McGrady,
J. E.; Raston, C. L.; Roberts, B. A.; Skelton, B. W.;White, A. H.J. Organo-
met. Chem. 2000, 607, 213.

5430 Organometallics, Vol. 29, No. 21, 2010
Limburg et al.
Figure 2. Molecular structures of 3a (only the R enantiomer is shown), 3b (only the S enantiomer is shown), and 4b (only the
S enantiomer is shown) with thermal ellipsoids at the 50% probability level. H atoms have been omitted for clarity.
˚
Table 1. Selected Bond Lengths (A) and Angles (deg) for 3a, 3b,
and 4b
the dichlorophosphanes is also a low-yield procedure, the
best-yield synthetic method for the preparation of primary
phosphanes is the procedure that was already described for
the synthesis of 1-phosphanyl-2-N,N-dimethylaminomethyl-
ferrocene.13 Thus, crude 2a or 2b was used without any further
purification to give racemic 5a in 66% yield and racemic 5b in
70% yield.
3a
3b
4b
P1-O1
P1-O2
P1-C1
P2-C3
P3-C6
O1-C11
O2-C13
O2-C12
1.639(1)
1.645(1)
1.804(1)
1.815(1)
1.630(2)
1.619(2)
1.810(2)
1.816(2)
1.810(2)
1.437(3)
1.442(3)
1.632(2)
1.619(2)
1.803(2)
1.815(2)
1.817(2)
1.415(3)
Formation of the primary phosphanes can be shown by
31P NMR spectroscopy. The resonances of the PPh2 groups
are very similar to those of the dichlorophosphane or the
dialkyl phosphonite derivatives [δP = -23.2 (5a); -23.7 and
-18.8 ppm (5b)]. The signal assigned to the PH2 group
appears as a triplet at lower frequencies [δP = -150.1
ppm, 1JPH = 199.6 Hz (5a); -150.3 ppm, 1JPH = 199.9 Hz
(5b)]. The electronegative or electropositive character of the
substituents on the phosphorus atom has a strong influence
on the direct carbon-phosphorus coupling constant, as was
already observed for 2, 3, and 4b. In the case of the primary
phosphanes, the lower electronegativity of the hydrogen
atoms results in a rather small direct carbon-phosphorus
1.432(2)
1.438(2)
1.433(3)
4.480(2)
3.187(2)
95.0(1)
103.3(1)
102.99(9)
P1 N1
3.158(1)
4.541(1)
95.55(6)
94.99(5)
102.34(6)
4.365(2)
3.422(2)
95.27(8)
103.23(8)
103.60(8)
3 3 3
P2 N1
3 3 3
C1-P1-O1
C1-P1-O2
O1-P1-O2
interactions might be the reason for the comparably short
N
N
P distance found in 3a and also in 4b, in which the
˚
P2 distance is only 3.187(2) A.
3 3 3
3 3 3
Synthesis of Primary Phosphanes 5a and 5b. According to
coupling, 1JCPH , of 9.5 Hz (5a) and 10.6 Hz (5b).
Scheme 1, all compounds described above are suitable start-
ing materials for the synthesis of the corresponding primary
phosphanes 5. Due to the higher reactivity of the P-Cl
bonds, the dichlorophosphanyl ferrocene complexes can be
reduced to the primary phosphanes by treatment with
LiAlH4 at room temperature, whereas the dialkylphospho-
nites can only be converted quantitatively by using a mixture
of LiAlH4 and SiMe3Cl. Even though the dialkylphospho-
nites are stable in solution and therefore easier to handle, the
most convenient and high-yielding method for preparing the
primary phosphanes is via the dichlorophosphanes. While
diethyl ether can be used as solvent for the reduction with
LiAlH4,10 THF is required for the reaction with LiAlH4/
SiMe3Cl.11,28 The variation in the reaction procedure seems
to be marginal but leads to a tremendous and yield-influen-
cing difference in the workup procedure. Therefore, the
primary phosphanes can be obtained only in poor yields of
45-49% from the dialkylphosphonites. As purification of
2
The primary phosphanes 5 are crystalline solids that are
air-stable in the solid state and stable in solution toward
oxygen over a prolonged period of time (at least 5 days).
They are thus two rare examples of air-stable primary
phosphanes.13,29 Despite intense efforts, no crystals of 5a
suitable for X-ray diffraction were obtained. However, the
molecular structure of 5b, which is depicted in Figure 3,
could be determined. It represents, to the best of our know-
ledge, the second structurally characterized primary phos-
phanylferrocene without a spacer between the phosphanyl
group and the ferrocene moiety. The hydrogen atoms at P1
could be located, whereas all other hydrogen atoms were
included in a riding mode. The P1-C1 bond length is within
the same range as in other reported aromatic primary
€
(29) (a) Hiney, R. M.; Higham, L. J.; Muller-Bunz, H.; Gilheany,
D. G. Angew. Chem., Int. Ed. 2006, 45, 7248. (b) Goodwin, N. J.;
Henderson, W.; Nicholson, B. K.; Fawcett, J.; Russell, D. R. J. Chem.
Soc., Dalton Trans. 1999, 1785. (c) Goodwin, N. J.; Henderson, W.;
Nicholson, B. K. Chem. Commun. 1997, 31. (d) Henderson, W.; Alley,
S. R. J. Organomet. Chem. 2002, 656, 120.
(28) Kyba, E. P.; Liu, S. T.; Harris, R. L. Organometallics 1983, 2,
1877.

Article
Organometallics, Vol. 29, No. 21, 2010 5431
the corresponding primary phosphanes from compounds
2, 3, and 4b. A facile method is the use of crude 2 and LiAlH4.
The primary phosphanes 1-diphenylphosphanyl-2-N,N-di-
methylaminomethyl-3-phosphanylferrocene(5a) and 1,10-bis-
(diphenylphosphanyl)-2-N,N-dimethylaminomethyl-3-phos-
phanylferrocene (5b) are rare examples of air-stable primary
phosphanes and could also be characterized by common
analytical techniques. 5b could further be structurally char-
acterized by X-ray diffraction.
Experimental Section
General Considerations. All manipulations were carried out
by standard Schlenk techniques under an atmosphere of dry,
high-purity nitrogen. Diethyl ether, toluene, and n-hexane were
taken from an MBRAUN solvent purification system MB SPS-
800; n-pentane was distilled from sodium. All these solvents
were nitrogen-saturated and stored over potassium mirror.
EtOH and MeOH were dried over sodium and distilled. H2O
was degassed in a nitrogen stream in an ultrasonic bath. 2-(N,N-
Dimethylaminomethyl)-1-diphenylphosphanylferrocene (1a)18
and 2-(N,N-dimethylaminomethyl)-1,10-bis(diphenylphosphanyl)-
ferrocene (1b)14 were synthesized according to literature pro-
cedures. Other chemicals were obtained from commercial
sources and used as supplied, except PCl3, which was distilled
and degassed with nitrogen prior to use. 1H (400.13 MHz), 13
C
Figure 3. Molecular structure of 5b (only the R enantiomer is
shown) with thermal ellipsoids at the 50% probability level. H
atoms except at P have been omitted for clarity. Selected bond
lengths (A) and angles (deg): P1-H1p 1.38(2), P1-H2p 1.38(2),
P1-C1 1.821(2), P2-C3 1.814(2), C1-P1-H1p 97.7(8), C1-
P1-H2p 97.3(9), H1p-P1-H2p 90(1).
(100.16 MHz), and 31P (161.98 MHz) NMR spectra were
recorded on a Bruker Avance DRX 400 spectrometer at
þ20 °C in C6D6 and referenced to tetramethylsilane (TMS).32
The signals of the 1H, 13C, and 31P NMR spectra were assigned
by 1H{31P}, 1H-1H COSY, APT, 1H-13C HMQC, 1H-13C
HMBC, and 13C{31P} experiments. EI mass spectra were re-
corded on a ZAB-HSQ-VG12-520 Analytical Manchester spec-
trometer or a MASPEC II spectrometer; ESI mass spectra were
recorded on a Bruker-Daltonics FT-ICR-MS APEX II. FTIR
spectra were recorded on a Perkin-Elmer Spectrum 2000 spec-
trometer. Melting points were determined in sealed glass capil-
laries under nitrogen and are uncorrected.
˚
phosphanes.13,30 Also, within the standard deviation, the
P1-H distances and the H-P1-H angle are in similar ranges
to those observed in other structurally characterized primary
phosphanes for which the protons were located.13,30b,31 In
contrast to 2a or 3b the dimethylaminomethyl group is bent
out of the plane of the cyclopentadienyl ring, so that no NfP
dative bond is present.
1-Dichlorophosphanyl-2-N,N-dimethylaminomethyl-3-diphenyl-
phosphanylferrocene (rac-2a). A solution of n-BuLi (5.10 mL,
12.08 mmol, 2.37 M in n-hexane) was slowly added to a solution
of 1a (4.69 g, 10.98 mmol) in diethyl ether (50 mL). The mixture
was stirred for 8 h and slowly added to a solution of PCl3 (1.81 g,
13.17 mmol) in diethyl ether (10 mL) at -80 °C. The mixture was
warmed to room temperature overnight and filtered. The solvent
was evaporated and the residue dried in vacuo. Recrystallization
from a mixtureof toluene and n-hexane (1:10) at -18 °C gave pure
2a as orange crystals. Yield: 3.83 g (66%). Mp: 131 °C (dec). 1H
Conclusion
The introduction of a primary phosphanyl group into
diphenylphosphanyl-substituted aminoalkylferrocene com-
plexes can be achieved by ortho-selective lithiation and
subsequent reaction with an electrophile. By this simple
reaction pathway we have synthesized the dichlorophospha-
nyl ferrocene complexes 1-dichlorophosphanyl-2-N,N-di-
methylaminomethyl-3-diphenylphosphanylferrocene (2a)
and 1-dichlorophosphanyl-2-N,N-dimethylaminomethyl-3,10-
bis(diphenylphosphanyl)ferrocene (2b) and the ferrocenyl-
phosphonites 1-diethoxyphosphanyl-2-N,N-dimethylamino-
methyl-3-diphenylphosphanylferrocene (3a) and 1-diethoxy-
phosphanyl-2-N,N-dimethylaminomethyl-3,10-bis(diphenyl-
phosphanyl)ferrocene (3b). We further prepared dimethyl-
ferrocenylphosphonite 4b by reaction of 3b with methanol.
Compound 2b could not be isolated but was detected by
31P{1H} NMR spectroscopy, whereas all other compounds
were fully characterizedby common analyticaltechniquesand
X-ray diffraction. Finally, we have presented the synthesis of
2
NMR: δ 1.91 (s, 6H, N(CH3)2), 3.03 (d, JHH = 14.4 Hz, 1H,
CH2N), 3.70 (d, 2JHH = 14.4 Hz, 1H, CH2N), 3.90 (s, 1H, C5H2 o
to PPh2), 4.04 (s, 5H, C5H5), 4.97 (s, 1H, C5H2 o to PCl2), 7.01 (br
s, 3H, C6H5), 7.10 (br s, 3H, C6H5), 7.27 (br s, 2H, C6H5 o to P),
and 7.50 (br s, 2H, C6H5 o to P) ppm. 13C{1H} NMR: δ 45.2 (s,
N(CH3)2), 56.9 (dd, 3JCPCl = 4.4 Hz, 3JCPPh = 7.2 Hz, CH2N),
2
2
71.8 (s, C5H5), 72.0 (d, 2JCPCl = 1.4 Hz, C5H2 o to PCl2), 73.5 (d,
2
2JCPPh = 1.6 Hz, C5H2 o to PPh2), 77.9 (d, 1JCPPh = 11.6 Hz,
2
2
1
FcPPh2), 85.1 (dd, JCPCl = 66.9 Hz, JCPPh = 3.1 Hz,
3
C
CFcPCl2), 97.1 (dd, JCPCl = 9.2 Hz, JCPPh = 22.8 Hz,
2 2
2
2
2
2
C
FcCH2N), 128.3-128.4 (3 signals overlapping with C6D6,
2
C6H5), 129.3 (s, C6H5), 132.7 (d, JCPPh = 19.1 Hz, C6H5 o to
=
2
P), 134.8 (d, 2JCPPh = 21.2 Hz, C6H5 o to P), 136.7 (d, 1JCPPh
2
2
1
10.7 Hz, CPhP), and 138.8 (d, JCPPh = 10.7 Hz, CPhP) ppm.
2
31P{1H} NMR: δ -23.0 (PPh2) and 138.3 (PCl2) ppm. FT-IR
(KBr; cm-1): 3069 (w), 3050 (w), 2945 (m), 2863 (s), 2828 (s),
2785 (s), 1962 (w), 1895 (w), 1823 (w), 1776 (w), 1728 (w), 1667
(w), 1585 (w), 1477 (m), 1457 (s), 1434 (s), 1410 (m), 1373 (m),
(30) (a) Bartlett, R. A.; Olmstead, M. M.; Power, P. P.; Sigel, G. A.
Inorg. Chem. 1987, 26, 1941. (b) Reiter, S. A.; Nogai, S. D.; Karaghiosoff,
K.; Schmidbaur, H. J. Am. Chem. Soc. 2004, 126, 15833.
(31) Brynda, M.; Geoffroy, M.; Bernardinelli, G. Chem. Commun.
1999, 961.
(32) Harris, R. K.; Becker, E. D.; Cabral de Menezes, S. M.; Good-
fellow, R.; Granger, P. Pure Appl. Chem. 2001, 73, 1795.

5432 Organometallics, Vol. 29, No. 21, 2010
Limburg et al.
1337 (w), 1310 (w), 1253 (m), 1226 (m), 1173 (m), 1131 (s), 1091
(s), 1024 (s), 1001 (s), 925 (w), 837 (s), 746 (s), 698 (s), 616 (w), 501
(s), 460 (s), 442 (s), and 416 (s). MS (EI pos. 14 eV; m/z): 527 [Mþ]
(99.6%), 500 (9.1%), 491 [(M - Cl)þ] (9.3%), 477 (10.5%), 455
(42.2%), 448[(M - HN(CH3)2 - Cl)þ] (13.3%), 441(11.1%), 427
[(HM - PCl2)þ] (100%), and 414 (20.3%). Anal. Calcd for
C25H25Cl2FeNP2: C, 56.85; H, 4.77; N, 2.65. Found: C, 56.96;
H, 4.79; N, 2.69.
1-Dichlorophosphanyl-2-N,N-dimethylaminomethyl-3,10-bis-
(diphenylphosphanyl)ferrocene (rac-2b). The procedure for the
preparation of 2a was followed using 1b (1.93 g, 3.15 mmol),
n-BuLi (1.54 mL, 3.78 mmol, 2.45 M in n-hexane), and PCl3
(0.56 g, 4.10 mmol). Pure 2b could not be obtained due to its
very fast decomposition in solution. 31P{1H} NMR: δ -21.2
(PPh2), -24.1 (PPh2), and 137.7 (PCl2) ppm.
o to P), and 7.54 (br m, 2H, C6H5 o to P) ppm. 13C{1H} NMR: δ
=
=
16.9 (d, 3JCP(OEt) = 4.2 Hz, OCH2CH3), 17.5 (d, 3JCP(OEt)
7.1 Hz, OCH2CH3), 44.6 (s, N(CH3)2), 56.6 (pt, JCP(OEt)
2
2
3
2
3JCPPh = 7.0 Hz, CH2N), 60.4 (d, JCP(OEt) = 3.7 Hz,
OCH2CH3), 64.1 (d, JCP(OEt) = 22.6 Hz, OCH2CH3), 73.8
2
2
2
2
2
(s, C5H4), 73.9 (s, C5H2), 74.0 (s, C5H2), 74.2 (s, C5H4), 74.3 (s,
C5H4), 76.8 (d, JCPPh = 24.3 Hz, C5H4 o to PPh2), 78.3 (d,
2
2
1JCPPh = 10.7 Hz, CFcPPh2 of C5H4), 81.7 (d, 1JCPPh = 14.0
2
2
Hz, CFcPPh2 of C5H2), 84.4 (dd, 1JCP(OEt) = 23.8 Hz, 3JCPPh
2.3 Hz, CFcP(OEt)2 of C5H2), 95.7 (dd, JCP(OEt) = 21.1 Hz,
=
2
22
2
2JCPPh = 24.5 Hz, CFcCH2N), 127.4-128.1(6 signals over-
lapping with C6D6, C6H5), 128.5 (s, C6H5), 128.7 (s, C6H5),
2
132.5 (d, 2JCPPh = 18.3 Hz, C6H5 o to P), 132.8 (d, 2JCPPh
=
2
2
18.9 Hz, C6H5 o to P), 134.1 (d, 2JCPPh = 20.7 Hz, C6H5 o to
2
P), 135.1 (d, 2JCPPh = 22.1 Hz, C6H5 o to P), 138.4 (d, 1JCPPh
10.6 Hz, CPhP), 138.6 (d, JCPPh = 11.5 Hz, CPhP), 140.4 (d,
=
2
2
1
1-Diethoxyphosphanyl-2-N,N-dimethylaminomethyl-3-diphenyl-
phosphanylferrocene (rac-3a). A solution of n-BuLi (4.94 mL,
12.36 mmol, 2.50 M in n-hexane) was slowly added to a solution
of 1a (4.40 g, 10.30 mmol) in diethyl ether (50 mL). After stirring
for 8 h, the reaction mixture was cooled to -80 °C and diethyl-
chlorophosphite (2.10 g, 13.39 mmol) was added slowly. The
reaction mixture was warmed to room temperature overnight
and filtered. The solvent was then evaporated and the residue
dried in vacuo for 1 h at 50 °C. Recrystallization from n-pentane
and storage at -64 °C gave 3a as an orange solid. Crystals suitable
for X-ray diffraction were obtained after recrystallizing twice from
n-pentane at -18 °C. Yield: 4.62 g (82%). Mp: 88 °C. 1H NMR: δ
1.13 (t, 3JHH = 7.0 Hz, 3H, OCH2CH3), 1.18 (t, 3JHH = 7.0 Hz,
3H, OCH2CH3), 2.06 (s, 6H, N(CH3)2), 3.75 (br m, 2H,
2
1
1JCPPh = 11.9 Hz, CPhP), and 141.0 (d, JCPPh = 9.6 Hz,
2
2
CPhP) ppm. 31P{1H} NMR: δ -24.4 (PPh2 at C5H2), -18.7
(PPh2 at C5H4), and 157.2 (P(OEt)2). FT-IR (KBr; cm-1): 3068
(m), 3052 (m), 2973 (s), 2935 (m), 2876 (m), 2815 (m), 2768 (m),
1953 (w), 1815 (w), 1585 (w), 1477 (m), 1453 (m), 1434 (s), 1385
(m), 1344 (w), 1326 (w), 1307 (w), 1260 (m), 1225 (m), 1180 (m),
1160 (m), 1131 (m), 1095 (m), 1028 (s), 921 (s), 841 (m), 742 (s),
697 (s), 631 (w), 503 (m), 472 (m), and 415 (w). MS (EI pos.
14 eV; m/z): 731 [Mþ] (100%), 687 [(M - N(CH3)2)þ] (3.1%),
610 [(M - Ph - HN(CH3)2)þ] and [(M - P(OEt)2)þ] (4.2%),
546 [(M - PPh2)þ] (11.9%). Anal. Calcd for C41H44FeNO2P3:
C, 67.31; H, 6.06; N, 1.91. Found: C, 67.32; H, 6.19; N, 1.88.
1-Dimethoxyphosphanyl-2-N,N-dimethylaminomethyl-3,10-bis-
(diphenylphosphanyl)ferrocene (rac-4b). Crude 3b can be used
directly without further purification. Crude 3b obtained from
1b (3.00 g, 4.91 mmol) was dissolved in methanol and refluxed for
10 min. The mixture was filtered and stored at 4 °C. Pure 4b
precipitated overnight as an orange powder. Crystals suitable
for X-ray diffraction were grown after recrystallization from
n-hexane at room temperature. Yield: 2.35 g (69%). Mp: 142 °C.
2
OCH2CH3), 3.76 (d, JHH = 13.3 Hz, 1H, CH2N), 3.91 (br m,
2H, OCH2CH3), 3.99 (d, 2JHH =13.3Hz, 1H, CH2N), 4.07 (s, 5H,
C5H5), 4.11 (s, 1H, C5H2 o to PPh2), 4.76 (s, 1H, C5H2 o to
P(OEt)2), 7.09 (br m, 6H, C6H5), 7.41 (br m, 2H, C6H5 o to P), and
7.69 (br s, 2H, C6H5 o to P) ppm. 13C{1H} NMR: δ 16.8
3
3
(d, JCP(OEt) = 4.2 Hz, OCH2CH3), 17.3 (d, JCP(OEt) = 6.4
= 6.3 Hz,
= 3.7 Hz,
2
2
Hz, OCH2CH3), 44.6 (s, N(CH3)2), 56.8 (pt, 3J
CP(OEt)2
3
2
3
CPPh2
CP(OEt)2
1H NMR: δ 2.05 (s, 6H, N(CH3)2), 3.39 (d, JPH = 9.2 Hz,
J
= 7.9 Hz, CH2N), 60.3 (d,
J
= 22.2 Hz, OCH2CH3), 70.6
2
CP(OEt)2
3H, OCH3), 3.47 (br s, 1H, C5H4), 3.60 (s, 3H, 3JPH = 9.2 Hz,
OCH3), 3.71 (d, 1H, JHH = 12.6 Hz, CH2N), 3.80 (br s, 1H,
OCH2CH3), 63.7 (d,
(s, C5H5), 71.2 (s, C5H2 o to P(OEt)2), 72.7 (d, JCPPh = 4.3
J
2
2
2
Hz, C5H2 o to PPh2), 80.7 (dd, 3JCP(OEt)2 = 2.0 Hz, 1JCPPh = 12.7
2
C5H2), 3.95 (d, 1H, JHH = 12.6 Hz, CH2N), 4.28 (br s, 1H,
2
Hz, CFcPPh2), 83.1 (dd, 1JCP(OEt) = 23.4 Hz, 3JCPPh = 2.6 Hz,
C5H4), 4.47 (s, 2H, C5H4 and C5H2), 4.88 (br s, 1H, C5H4), 7.00
(br m, 12H, C6H5), 7.34 (br m, 6H, C6H5 o to P), and 7.53 (br m,
2
2
CFcP(OEt)2), 95.4 (dd, 2JCP(OEt) = 21.7 Hz, 2JCPPh = 24.5 Hz,
2
2
2H, C6H5 o to P) ppm. 13C{1H} NMR: δ 44.5 (s, N(CH3)2), 50.8
(s, OCH3), 55.1 (d, JCP(OMe) = 22.5 Hz, OCH3), 56.6 (pt,
CFcCH2N), 127.4 (s, C6H5), 127.5-127.9 (2 signals, obscured by
C6D6, C6H5), 128.7 (s, C6H5), 132.5 (d, 2JCPPh = 18.4 Hz, C6H5
o to P), 135.4 (d, JCPPh = 22.0 Hz, C6H5 o to P), 139.0 (d,
2
2
2
2
3JCP(OMe) = 3JCPPh = 7.0 Hz, CH2N), 73.7 (s, C5H4), 73.9 (s,
2
2
2
1JCPPh = 10.9 Hz, CPhP), and 141.1 (d, 1JCPPh = 9.9 Hz, CPhP)
C5H4 and C5H2 o to P(OMe)2), 74.1 (d, 2JCPPh = 4.5 Hz, C5H4 o
2
2
2
ppm. 31P{1H} NMR: δ -23.9 (PPh2) and 158.4 (P(OEt)2). FT-IR
(KBr; cm-1): 3054 (m), 2974 (s), 2941 (s), 2863 (s), 2812 (s), 2768
(s), 1585 (w), 1475 (m), 1453 (m), 1434 (s), 1382 (s), 1343 (w), 1249
(m), 1226 (m), 1178 (m), 1160 (m), 1128 (s), 1093 (s), 1044 (s), 1000
(m), 911 (s), 843 (m), 816 (m), 748 (s), 723 (s), 698 (s), 623 (w), 526
(m), and 498 (s). MS (EI pos. 14 eV; m/z): 547 [Mþ] (100%), 518
[(M - CH2CH3)þ] (3.8%), and 504 [(M - N(CH3)2)þ] (4.0%).
Anal. Calcd for C29H35FeNO2P2: C, 63.63; H, 6.44; N, 2.56.
Found: C, 63.65; H, 6.51; N, 2.57.
to PPh2), 74.2 (s, C5H4), 76.5 (dd, 3JCP(OMe) = 3.9 Hz, 2JCPPh
=
2
2
23.8 Hz, C5H2 o to PPh2), 78.5 (d, 1JCPPh = 10.7 Hz, CFcPPh2 of
C5H4), 81.8 (dd, JCP(OMe) = 1.9 Hz, JCPPh = 13.9 Hz,
2
3
1
2
2
1
FcPPh2 of C5H2), 83.3 (dd, JCP(OMe) = 25.4 Hz, JCPPh =
3
C
2 2
2.7 Hz, CFcP(OMe)2 of C5H2), 95.9 (dd, 2JCP(OMe) = 21.3 Hz,
2
2JCPPh = 24.5 Hz, CFcCH2N), 127.2-128.2 (6 signals over-
lapping with C6D6, C6H5), 128.5 (s, C6H5), 128.8 (s, C6H5), 132.5
2
(d, 2JCPPh = 18.3 Hz, C6H5 o to P), 132.9 (d, 2JCPPh = 19.0 Hz,
2
2
C6H5 o to P), 134.1 (d, 2JCPPh = 20.6 Hz, C6H5 o to P), 135.1 (d,
2
1
1-Diethoxyphosphanyl-2-N,N-dimethylaminomethyl-3,10-bis-
(diphenylphosphanyl)ferrocene (rac-3b). The procedure for the
preparation of 3a was followed using 1b (2.89 g, 4.73 mmol),
n-BuLi (2.31 mL, 5.67 mmol, 2.45 M in n-hexane), and diethyl-
chlorophosphite (1.03 g, 6.62 mmol). Pure 3b was obtained as
an orange solid by recrystallization from EtOH at -64 °C
followed by a second recrystallization from n-hexane at
-64 °C. Crystals suitable for X-ray diffraction were obtained
after a third recrystallization from n-pentane at -18 °C. Yield:
2.35 g (68%). Mp: 55 °C. 1H NMR: δ 1.14 (t, 3JHH = 7.0 Hz,
3H, OCH2CH3), 1.27 (t, 3JHH = 7.0 Hz, 3H, OCH2CH3), 2.05
(s, 6H, N(CH3)2), 3.46 (s, 1H, C5H4), 3.76 (br m, 3H, OCH2CH3
and CH2N), 3.95 (br m, 4H, OCH2CH3, CH2N and C5H2),
4.31 (s, 1H, C5H4), 4.50 (s, 1H, C5H4), 4.52 (s, 1H, C5H4), 4.91
(s, 1H, C5H2), 6.99 (br m, 12H, C6H5), 7.34 (br m, 6H, C6H5
2JCPPh = 22.1 Hz, C6H5 o to P), 138.3 (d, JCPPh = 10.5 Hz,
2
2
C
PhP), 138.5 (d, 1JCPPh = 11.5 Hz, CPhP), 140.3 (d, 1JCPPh
=
2
2
1
12.0 Hz, CPhP), and 141.0 (d, JCPPh = 9.6 Hz, CPhP) ppm.
2
31P{1H} NMR: δ -24.5 (PPh2 at C5H2), -18.8 (PPh2 at C5H4),
and 162.9 (P(OMe)2) ppm. FT-IR (KBr; cm-1): 3421 (bw), 3069
(w), 3051 (w), 2969 (m), 2934 (m), 2856 (w), 2813 (m), 2768 (m),
2363 (w), 2346 (w), 1774 (w), 1702 (w), 1655 (w), 1586 (w), 1570
(w), 1560 (w), 1508 (w), 1478 (m), 1452 (m), 1434 (s), 1392 (w),
1340 (w), 1308 (w), 1261 (m), 1226 (m), 1196 (m), 1178 (m), 1162
(m), 1131 (s), 1091 (m), 1027 (s), 1017 (s), 841 (m), 818 (m), 741
(s), 698 (s), 673 (w), 630 (w), 539 (m), 520 (m), 502 (m), 489 (m),
478 (m), 468 (m), 453 (m), and 419 (w). MS (ESI pos., CH2Cl2/
CH3CN): 734 [(M þ O þ CH3)þ] (13.7%), 718 [(M þ CH3)þ]
(59.4%), 704 [(M þ H)þ] (100%), 672 [(M - OCH3)þ] (16.9%),
659 [(M - N(CH3)2)þ] (48.7%), 626 [(M - C6H5)þ] (13.3%), 567

Article
Organometallics, Vol. 29, No. 21, 2010 5433
Table 2. Crystal Data and Structure Refinement for Compounds 2-5
2a
3a
3b
4b
5b
formula
fw (g/mol)
T (K)
C
528.15
130(2)
monoclinic
P21/n
8.8526(3)
9.7236(3)
28.5180(7)
90
97.079(3)
90
2436.1(1)
4
1.440
0.983
1088
0.4 ꢀ 0.15 ꢀ 0.05
2.88-30.51
-12 e h e 12
-13 e k e 13
-40 e l e 40
27 233
7435 (0.0554)
0.903
0.1005
25H25Cl2FeNP2
C29H35FeNO2P2
547.37
130(2)
triclinic
P1
9.9909(2)
10.5284(2)
13.2106(2)
92.110(1)
93.214(1)
103.366(1)
1348.06(4)
2
1.349
0.705
576
0.5 ꢀ 0.4 ꢀ 0.3
2.69-30.51
-14 e h e 14
-15 e k e 15
-18 e l e 18
47 842
C41H44FeNO2P3 C5H12
3
C39H40FeNO2P3
703.48
130(2)
orthorhombic
P212121
12.8067(3)
16.4070(5)
17.0077(4)
90
90
90
3573.7(2)
4
1.308
0.591
1472
0.4 ꢀ 0.3 ꢀ 0.05
2.95-26.37
-11 e h e 16
-10 e k e 20
-20 e l e 21
14 020
7294 (0.0385)
0.788
0.0566
C37H36FeNP3
643.43
130(2)
triclinic
P1
10.2115(4)
11.4581(4)
14.7424(6)
99.385(3)
97.342(3)
108.169(3)
1587.4(1)
2
1.346
0.654
672
0.2 ꢀ 0.1 ꢀ 0.1
2.62-26.37
-12 e h e 12
-14 e k e 14
-18 e l e 18
29 482
803.68
130(2)
cryst syst
space group
triclinic
P1
˚
a (A)
10.0395(2)
10.9011(3)
22.0156(5)
93.855(2)
102.631(2)
111.892(3)
2151.92(9)
2
1.240
0.499
852
0.3 ꢀ 0.3 ꢀ 0.2
2.56-30.51
-14 e h e 14
-15 e k e 15
-28 e l e 31
36 205
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
3
˚
V (A )
Z
Dc (g/cm-3
)
μ (mm-1
F(000)
cryst size (mm)
)
θ range data collection (deg)
ranges of h,k,l
no. of reflns collected
no. of indept reflns and (Rint
GOF (F2)
final R1 (all data)
wR2 (all data)
Flack param x
)
8220 (0.0260)
1.089
0.0385
13 085 (0.0299)
1.008
0.0743
6500 (0.0593)
0.872
0.0681
0.0856
0.0927
0.1284
0.0500
0.004(11)
0.0679
[(M - C6H5 - N(CH3)2)þ] (17.2%). Anal. Calcd for C39H40Fe-
NO2P3: C, 66.58; H, 5.73; N, 1.99. Found: C, 66.01; H, 5.81;
N, 1.97.
(dd, 2JHH = 12.4 Hz, 1JPH = 199.9 Hz, 1H, PH2), 3.82 (s, 5H,
C5H5), 3.89 (dd, 2JHH = 12.4 Hz, 1JPH = 199.4 Hz, 1H, PH2),
3.91 (d, 2JHH = 12.8 Hz, 1H, CH2N), 3.97 (br s, 1H, C5H2 o to
PPh2), 4.24 (br s, 1H, C5H2 o to PH2), 7.04 (br m, 6H, C6H5),
7.36 (br m, 2H, C6H5 o to P), and 7.64 (br m, 2H, C6H5 o to P)
General Procedure for the Reduction of Phosphonites 3 and 4b
to Primary Phosphanes 5. The reducing agent was prepared by
adding a solution of SiMe3Cl (2 equiv) in thf to a suspension of
an equimolar amount of LiAlH4 in thf at 0 °C. The resulting
suspension was stirred for 2 h at room temperature. The
phosphonite (1 equiv) was dissolved in thf and slowly added
to the reducing agent at 0 °C. After stirring overnight at room
temperature, the resulting suspension was hydrolyzed by slowly
adding an excess of methanol at 0 °C. The reaction mixture was
stirred for 1 h at 0 °C and then warmed to room temperature.
The solvent was evaporated in vacuo and the orange residue
extracted with n-hexane for 5 h. After removal of the solvent the
remaining orange powder was purified as described below
starting from 2a.
1-Diphenylphosphanyl-2-N,N-dimethylaminomethyl-3-phos-
phanylferrocene (5a). 3a (2.42 g, 4.42 mmol), SiMe3Cl (0.96 g,
8.84 mmol), LiAlH4 (0.34 g, 8.96 mmol). Yield: 0.91 g (45%
based on 3a).
1,10-Bis(diphenylphosphanyl)-2-N,N-dimethylaminomethyl-
3-phosphanylferrocene (5b). 3b (2.35 g, 3.21 mmol), SiMe3Cl
(0.70 g, 6.44 mmol), LiAlH4 (0.25 g, 6.59 mmol). Yield: 0.95 g
(46% based on 3b).
4b (1.88 g, 2.67 mmol), SiMe3Cl (0.58 g, 5.34 mmol), LiAlH4
(0.21 g, 5.53 mmol). Yield: 0.84 g (49% based on 4b).
1-Diphenylphosphanyl-2-N,N-dimethylaminomethyl-3-phos-
phanylferrocene (5a) Starting from 2a. Crude 2a can be used
directly without further purification. Crude 2a obtained from
1a (2.91 g, 6.81 mmol) was dissolved in diethyl ether (50 mL)
(solution became slowly turbid due to decomposition of 2a)
and was added to a slurry of LiAlH4 (0.52 g, 13.62 mmol) in
diethyl ether (10 mL) at room temperature. The mixture was
stirred overnight, filtered, and carefully hydrolyzed with
slightly basic (one KOH pellet) water (50 mL) at 0 °C. After
stirring for 1 h at room temperature the organic layer was
separated and dried over MgSO4. After filtration the solvent
was removed and the oily residue dried in vacuo. Recrystalli-
zation from ethanol at -18 °C gave 5a as an orange powder.
Yield: 2.06 g (66% based on 1a). Mp: 68.5 °C. 1H NMR: δ 2.00
(s, 6H, N(CH3)2), 3.54 (d, 2JHH = 12.8 Hz, 1H, CH2N), 3.75
ppm. 13C{1H} NMR: δ 44.5 (s, N(CH3)2), 56.8 (dd, 3JCPH
=
2
1.5 Hz, 3JCPPh = 8.6 Hz, CH2N), 69.6 (dd, 1JCPH = 9.5 Hz,
2
2
3JCPPh = 3.0 Hz, CFcPH2), 70.9 (s, C5H5), 72.7 (dd, 3JCPH
=
=
=
2
2
3.2 Hz, 2JCPPh = 4.4 Hz, C5H2 o to PPh2), 77.1 (d, 2JCPH
2
2
9.3 Hz, C5H2 o to PH2), 80.3 (dd, 3JCPH = 1.5 Hz, 1JCPPh
2
2
13.0 Hz, CFcPPh2), 96.0 (dd, 2JCPH = 11.1 Hz, 2JCPPh = 25.2
2
2
Hz, CFcCH2N), 127.0-128.0 (3 signals overlapping with
2
C6D6, C6H5), 128.8 (s, C6H5), 132.5 (d, JCPPh = 18.2 Hz,
2
C6H5 o to P), 135.4 (d, 2JCPPh = 22.0 Hz, C6H5 o to P), 138.8
2
(d, 1JCPPh = 10.4 Hz, CPhP), and 140.8 (d, 1JCPPh = 9.9 Hz,
2
2
1
C
PhP) ppm. 31P NMR: δ -150.1 (t, JPH = 199.6 Hz, PH2),
-23.2 (s, PPh2). FT-IR (KBr; cm-1): 3069 (m), 3053 (m), 2972
(m), 2939 (s), 2857 (m), 2812 (s), 2763 (s), 2299 (s), 2266 (s),
1957 (w), 1891 (w), 1776 (w), 1723 (w), 1662 (w), 1586 (w), 1476
(m), 1455 (m), 1434 (s), 1403 (m), 1343 (w), 1326 (w), 1308 (w),
1256 (m), 1228 (m) 1179 (m), 1153 (w), 1132 (m), 1092 (s), 1025
(s), 1002 (s), 843 (s), 818 (s), 745 (s), 698 (s), 649 (w), 504 (s), and
470 (s). MS (EI pos. 14 eV; m/z): 459 [Mþ] (42.6%) and 414
[(M - HN(CH3)2)þ] (100%). Anal. Calcd for C25H27FeNP2:
C, 65.38; H, 5.93; N, 3.05. Found: C, 65.27; H, 5.91; N, 3.01.
1,10-Bis(diphenylphosphanyl)-2-N,N-dimethylaminomethyl-
3-phosphanylferrocene (5b) Starting from 2b. The procedure
for the preparation of 5a was followed starting from crude
2b obtained in situ from 1b (1.93 g, 3.15 mmol) and LiAlH4
(0.12 g, 3.16 mmol). The yellow-orange solid was recrystal-
lized from ethanol at -64 °C. Crystals suitable for X-ray
diffraction were obtained after a second recrystallization
from refluxing ethanol by slowly cooling to room tempera-
ture. Yield: 1.41 g (70% based on 1b). Mp: 134 °C. 1H NMR:
2
δ 1.98 (s, 6H, N(CH3)2), 3.37 (s, 1H, C5H4), 3.53 (d, JHH
=
12.6 Hz, 1H, CH2N), 3.69 (dd, 2JHH = 12.2 Hz, 1JPH = 202.7
Hz, 1H, PH2), 3.83 (s, 1H, C5H4), 3.85 (d, JHH = 12.6 Hz,
2
2
1
1H, CH2N), 3.88 (dd, JHH = 12.2 Hz, JPH = 198.8 Hz,
1H, PH2), 4.03 (s, 2H, C5H2 o to PPh2 and C5H4), 4.35 (s,
1H, C5H4), 4.48 (s, 1H, C5H2 o to PH2), 6.99 (br m, 12H,
C6H5), 7.37 (br m, 6H, C6H5 o to P), and 7.52 (br m, 2H,
C6H5 o to P) ppm. 13C{1H} NMR: 44.5 (s, N(CH3)2), 56.6

5434 Organometallics, Vol. 29, No. 21, 2010
Limburg et al.
3
(d, JCPPh = 7.5 Hz, CH2N), 71.1 (dd, JCPH = 10.6 Hz,
1
cooled in a nitrogen stream. Crystallographic measurements
were made using an Oxford Diffraction Xcalibur S diffracto-
meter. Data were collected by using monochromatic Mo
2
2
3JCPPh = 2.9 Hz, CFcPH2), 73.5 (d, JCPPh = 9.2 Hz, C5H4),
73.6 (d, JCPPh = 5.0 Hz, C5H4), 73.9 (s, C5H4), 74.6 (d,
2
2
2
3
2
˚
JCPPh = 4.4 Hz, C5H4), 77.7 (dd, JCPH = 2.8 Hz, JCPPh =
2
KR radiation (λ = 0.71073 A). The structures were solved by
2
2
19.7 Hz, C5H2 o to PPh2), 78.6 (d, 1JCPPh = 10.1 Hz, CFcPPh2
direct methods33 and refined on F2 by full-matrix least-squares
techniques (SHELX97).34 All non-hydrogen atoms were refined
anisotropically; hydrogen atoms were calculated on idealized
positions as a riding model and refined isotropically with the
exception of 3a, for which all H atoms were located on difference
Fourier maps calculated at the final stage of the structure
refinement, and the PH2 fragment for 5b. Figures show ORTEP
depictions.35 Crystal data and details of data collection and
refinement are given in Table 2. Further details are included in
the Supporting Information.
2
of C5H4), 79.8 (dd, 2JCPH = 6.2 Hz, 3JCPPh = 3.3 Hz, C5H2 o
to PH2), 81.1 (dd, JCPH = 1.3 Hz, JCPPh = 13.9 Hz,
2
2
3
1
2
2
2
FcPPh2 of C5H2), 96.4 (dd, JCPH = 12.4 Hz, JCPPh =
2
C
2
2
25.2 Hz, CFcCH2N), 127.7-128.1 (4 signals overlapping with
C6D6, C6H5), 128.2 (s, C6H5), 128.3 (s, C6H5), 128.4 (s,
2
C6H5), 128.9 (s, C6H5), 132.5 (d, JCPPh = 18.5 Hz, C6H5 o
2
2
to P), 133.4 (d, JCPPh = 19.5 Hz, C6H5 o to P), 133.8 (d,
2
2JCPPh = 20.1 Hz, C6H5 o to P), 135.1 (d, 2JCPPh = 22.1 Hz,
C6H5 o to P), 138.2 (d, JCPPh = 10.1 Hz, CPhP), 138.7 (d,
2
2
1
2
1JCPPh = 11.3 Hz, CPhP), 139.7 (d, 1JCPPh = 11.7 Hz, CPhP),
CCDC 775092 (rac-2a), 775093 (rac-3a), 775094 (rac-3b),
775095 (rac-4b), and 775096 (rac-5b) contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html
(or from the Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EZ, UK; fax: (þ44)1223-336-
033; or deposit@ccdc.cam.uk).
2
2
1
and 140.8 (d, JCPPh = 9.7 Hz, CPhP) ppm. 31P NMR: δ
2
-150.3 (t, 1JPH = 199.9 Hz, PH2), -23.7 (PPh2 at C5H2), and
-18.8 (PPh2 at C5H4). FT-IR (KBr; cm-1): 3423 (bm), 3052
(w), 2964 (s), 2764 (w), 2271 (m), 1584 (w), 1508 (s), 1477 (m),
1433 (s), 1262 (s), 1173 (m), 1130 (w), 1090 (m), 1024 (s), 878
(w), 836 (m), 815 (m), 745 (s), 697 (s), 560 (w), 519 (w), 500 (m),
and 468 (m). MS (EI pos. 14 eV; m/z): 643 [Mþ] (35.2%), 611
[(M - PH)þ] (10.7%), 598 [(M - HN(CH3)2)þ] (100%), 568
(6.6%), 333 (8.7%), and 250 (8.2%). Anal. Calcd for C37H36-
FeNP3: C, 69.06; H, 5.64; N, 2.18. Found: C, 68.72; H, 5.64;
N, 2.15.
Acknowledgment. We thank the EU-COST Action
CM0802 “PhoSciNet”, the Graduate School “Leipzig
School of Natural Sciences—Building with Molecules and
Nano-objects” (BuildMoNa), and the Studienstiftung des
Deutschen Volkes (doctoral grant for C.L.) for generous
financial support and gratefully acknowledge generous
donations of chemicals from Chemetall GmbH and
BASF SE.
X-ray Structure Determinations. Suitable crystals were
mounted on a glass needle with perfluoropolyalkyl ether and
(33) For 2a, 3a, 3b, 4b: SIR92—A program for crystal structure
solution. Altomare, A.; Cascarano, G.; Giacovazzo, C.; Guagliardi,
A. J. Appl. Crystallogr. 1993, 26, 343.
(34) SHELX97 (includes SHELXS97, SHELXL97): Sheldrick,
Supporting Information Available: Crystallographic data for
rac-2a, rac-3a, rac-3b, rac-4b, and rac-5b as CIF files. This
material is available free of charge via the Internet at http://
pubs.acs.org.
G. M. SHELX97, Programs for Crystal Structure Analysis (Release
€
97-2); University of Gottingen: Germany, 1997.
(35) Johnson, C. R. ORTEP; Oak Ridge National Laboratory: Oak
Ridge, TN, 1976.