Reaction of NaP5 with half-sandwich complexes of nickel: The first example of an Ni-promoted transformation of the P5- anion

Article abstract of DOI:10.1021/om050078u

The reaction of sodium pentaphosphacyclopentadienide, NaP₅, with [Cp*NiBr(PPh₃)] (Cp* = η⁵-C ₅Me₅) gave only decomposition products. However, with [(η³-C₃Ph₃)NiBr(PMe<

Full text of DOI:10.1021/om050078u

Organometallics 2005, 24, 2233-2236
2233
Reaction of NaP5 with Half-Sandwich Complexes of
Nickel: The First Example of an Ni-Promoted
-
Transformation of the P5 Anion
Vasily Miluykov,*,† Alexandr Kataev,† Oleg Sinyashin,† Peter Lo¨nnecke,‡ and
Evamarie Hey-Hawkins*,‡
A. E. Arbuzov Institute of Organic and Physical Chemistry, Russian Academy of Sciences,
Arbuzov Street 8, Kazan 420088, Russian Federation, and Institut fu¨r Anorganische Chemie,
Universita¨t Leipzig, Johannisallee 29, D-04103 Leipzig, Germany
Received February 3, 2005
The reaction of sodium pentaphosphacyclopentadienide, NaP5, with [Cp*NiBr(PPh3)] (Cp*
) η5-C5Me5) gave only decomposition products. However, with [(η3-C3Ph3)NiBr(PMe2Ph)]
sodium 1,2-diphosphacyclopentadienide was formed, which is the product of an unusual Ni-
promoted degradation of the pentaphosphacyclopentadienide anion.
Introduction
found that the stability of the resulting pentaphospha-
ferrocenes is highly dependent on the number and
nature of the substituents on the cyclopentadienyl ring.
Thus, only pentaphosphaferrocenes in which the cyclo-
pentadienyl ring has at least four methyl or two tert-
butyl or trimethylsilyl groups are stable.
Compounds that contain “naked” oligophosphorus
fragments Px without substituents on the phosphorus
atoms are highly interesting, as they can be considered
as possible intermediates formed by cleavage of white
phosphorus by electrophilic and/or nucleophilic re-
agents. The investigation of their structure and chemi-
cal behavior is one possible method for understanding
the pathways of the cleavage of white phosphorus and
thus to control this process.1,2 In addition, Px fragments
are very interesting ligands or building blocks for the
construction of various organometallic complexes and
clusters, such as unusual one- and two-dimensional
polymeric compounds3 and a unique fullerene-like mol-
ecule,4 which were obtained from pentamethylpenta-
phosphaferrocene and copper(I) halides. Furthermore,
these compounds are very important for understanding
the diagonal and isolobal relationship between carbon
and phosphorus.5
In addition to the steric factor there is also an
electronic factor that determines the stability of sand-
wich complexes with P5 ligands. Thus, most of the
transition metal complexes with P5 ligands have 18
valence electrons, an exception being [Ti{η5-(cyclo-
P5)}2]2- 8,9
.
We now report on our attempts to extend this chem-
istry to nickelocene derivatives with 18 or 20 valence
electrons.
Results and Discussion
It is known that the reaction of half-sandwich com-
plexes of nickel with lithium cyclopentadienide, CpLi,
gives 20-valence-electron nickelocenes.10 However, we
found that NaP5 reacts with [Cp*NiBr(PPh3)] (Cp* )
η5-C5Me5)10 (1) to give only decomposition products
under various conditions (eq 1).
In this respect the pentaphosphacyclopentadienide
anion is especially interesting, as this compound is one
of the few examples of phosphorus anions for which the
organometallic chemistry of the carbon analogue, the
cyclopentadienide anion, is well known and thus allows
the reactivity of the two compounds to be compared.
We have previously studied the chemical behavior of
NaP5 toward half-sandwich complexes of iron6,7 and
* To whom correspondence should be addressed. (V.M.) Fax:
+7-8432/767-424. E-mail: miluykov@iopc.knc.ru, oleg@iopc.knc.ru.
(E.H.-H.) Fax: + 49 (0)341-9739319. E-mail: hey@rz.uni-leipzig.de.
† A. E. Arbuzov Institute of Organic and Physical Chemistry.
‡ Institut fu¨r Anorganische Chemie.
In all cases a black precipitate formed, which was
insoluble in common solvents (hexane, toluene, thf, CH2-
Cl2, dmf, dmso). In the 31P NMR spectrum of the
reaction mixture no signal was detected for NaP5 (at
(1) Ehses, M.; Romerosa, A.; Peruzzini, M. Top. Curr. Chem. 2002,
220, 107-140.
(2) Scherer, O. J. Angew. Chem., Int. Ed. 2000, 39, 1029-1030.
(3) Bai, J.; Virovets, A. V.; Scheer, M. Angew. Chem., Int. Ed. 2002,
41, 1737-1740.
(7) Miluykov, V. A.; Sinyashin, O. G.; Lo¨nnecke, P.; Hey-Hawkins,
E. Mendeleev Commun. 2003, 212-213.
(4) Bai, J.; Virovets, A. V.; Scheer, M. Science 2003, 300, 781-783.
(5) Dillon, K. B.; Mathey, F.; Nixon, J. F. Phosphorus: The Carbon
Copy: From Organophosphorus to Phospha-organic Chemistry; Wiley-
VCH: Weinheim, 1998.
(6) Miluykov, V. A.; Sinyashin, O. G.; Scherer, O. J.; Hey-Hawkins,
E. Mendeleev Commun. 2002, 1-2.
(8) Urnezius, E.; Brennessel, W. W.; Cramer, C. J.; Ellis, J. E.; von
Rague´ Schleyer, P. Science 2002, 295, 832-834.
(9) Lein, M.; Frunzke, J.; Frenking, G. Inorg. Chem. 2003, 42, 2504-
2511.
(10) Mise, T.; Yamazaki, H. J. Organomet. Chem. 1978, 164, 391-
400.
10.1021/om050078u CCC: $30.25 © 2005 American Chemical Society
Publication on Web 03/31/2005

2234 Organometallics, Vol. 24, No. 9, 2005
Miluykov et al.
Figure 2. Molecular structure of the cation and the 1,2-
diphospha-3,4,5-triphenylcyclopentadienide anion in 3.
Hydrogen atoms omitted for clarity; thermal ellipsoids
drawn at 50% probability.
Figure 1. Molecular structure of 2. Hydrogen atoms
omitted for clarity; thermal ellipsoids drawn at 50% prob-
ability.
However, an X-ray structure determination carried
out on crystals obtained from toluene at -30 °C showed
that this signal is due to the 1,2-diphospha-3,4,5-
triphenylcyclopentadienide anion, obtained as the so-
dium salt, which is the first structurally characterized
1,2-diphosphacyclopentadienide anion (Figure 2, Table
3).
+470 ppm). The fact that PPh3 can be isolated from the
solution also indicates that a reaction between 1 and
NaP5 has taken place. However, the proposed 20-
electron complex [Cp*NiP5] is apparently unstable.
Thus, replacement of the Cp* ligand by a cyclopro-
penyl ligand should result in stable 18-valence-electron
nickel sandwich complexes with a P5 fragment. A
similar reaction of the carbon analogue of NaP5, the Cp-
anion, with [(η3-Ph3C3)NiCl(py)2] to give [CpNi(η3-
Ph3C3)] was already described.11
The starting material 2 can be prepared by a known
procedure12 from [Ni(cod)2], triphenylcyclopropenyl bro-
mide, and 2 equiv of PMe2Ph (eq 2). Complex 2 was
characterized by NMR spectroscopy and X-ray analysis
(Figure 1).
The formation of a 1,2-diphosphacyclopentadienide
anion, which was, however, only characterized by 31P
NMR spectroscopy and mass spectrometry, was previ-
ously reported by F. Mathey and co-workers.14
The anion and the cation are located on a crystal-
lographic C2 axis, which passes through Na(1) and C(2).
The three carbon and two phosphorus atoms are copla-
nar. The P-P distance of 2.111(3) Å is similar to those
in [Cp*FeP5]15 and [Li(dme)3][cyclo-(1,2,4-P3C2But2)].16
The phenyl rings have a propeller-like orientation with
dihedral angles of ca. 127°. The sodium cation is
solvated by two diglyme molecules in a “meridional-like”
fashion, and no cation-anion interaction is observed,
which is in contrast to the potassium salt of 1,3-
diphosphacyclopentadienide,17 in which the anion in-
teracts with the potassium cation (η5 coordination).
In 3, the solvated sodium cations and the 1,2-diphos-
phacyclopentadienide rings are oriented in columns
along the b axis, and the C3P2 planes have a parallel
arrangement (Figure 3).
The cyclopropenylium ring has an η3 coordination
mode, and the C-C (1.425(8) to 1.432(8) Å) and Ni-C
(1.970(6) to 2.016(6) Å) bond lengths differ only slightly
(Table 2). The shortest distance of Ni(1) to the C(19)-
C(20)-C(21) plane is 1.815(2) Å.
Complex 2 was treated with NaP5 at room tempera-
ture (eq 3). After 6 h two signals were observed in the
31P NMR spectrum of the reaction mixture, of which
that at -9 ppm was assigned to [Ni(PMe2Ph)4],13 while
the singlet at 190 ppm is in the range characteristic for
metal sandwich complexes with P5 fragments.
Even though it is unclear how the diphosphacyclo-
pentadienide anion is formed, nickel(II) plays an im-
portant part in this reaction. Thus, no reaction is
observed between triphenylcyclopropenyl bromide and
NaP5 in diglyme at room temperature or at 90 °C (eq
4).
In summary, an unusual Ni-promoted reaction of
NaP5 with a cyclopropenyl ring to give the structurally
characterized 1,2-diphosphacyclopentadienide anion was
observed.
(14) Maigrot, N.; Avarvari, N.; Charrier, C.; Mathey, F. Angew.
Chem., Int. Ed. Engl. 1995, 34, 590-592.
(15) Scherer, O. J.; Bruck, T.; Wolmersha¨user, G. Chem. Ber. 1988,
121, 935-938.
(11) Rausch, M. D.; Tuggle, R. M.; Weaver, D. L. J. Am. Chem. Soc.
1970, 92, 4981-4982.
(12) Cecconi, F.; Ghilardi, C. A.; Mindollini, S.; Monet, S.; Orlandini,
A. Angew. Chem., Int. Ed. Engl. 1986, 25, 833-834.
(13) Tolman, C. A.; Reutter, D. W.; Seidel, W. C. J. Organomet.
Chem. 1976, 117, C30-C33.
(16) Becker, G.; Becker, W.; Knebl, R.; Schmidt, H.; Weeber, U.;
Westerhausen, M. Nova Acta Leopoldina 1985, 59, 55-67.
(17) Cloke, F. G. N.; Hitchcock, P. B.; Nixon, J. F.; Wilson, D. J.
Organometallics 2000, 19, 219-220.

Reaction of NaP5 with Nickel Complexes
Organometallics, Vol. 24, No. 9, 2005 2235
Table 1. Crystallographic Data for [(η3-C3Ph3)NiBr(PMe2Ph)] (2) and [Na(diglyme)2][cyclo-(1,2-P2C3Ph3)] (3)
2
3
empirical formula
fw
cryst color/habit
cryst size/mm
temperature/K
wavelength λ/pm
cryst syst
C
37H37BrNiP2
C33H43NaO6P2
620.60
pale pink/thin plate
0.40 × 0.10 × 0.01
210(2)
71.073
monoclinic
P2/n
682.23
red/prism
0.20 × 0.05 × 0.05
210(2)
71.073
monoclinic
P21/n
space group
unit cell dimens
a/pm
1232.3(3)
1748.7(5)
1506.8(4)
99.24(1)
1290.5(4)
1097.8(3)
1319.2(4)
111.30(1)
1.7413(8)
2
b/pm
c/pm
â/deg
V/nm3
3.2049(15)
4
Z
density (calcd)/Mg‚m-3
absorption coeff/mm-1
F(000)
1.414
1.184
1.977
0.177
1408
660
θ range for data collection
index ranges
1.80 to 23.28°
-13 e h e13
-19 e k e 19
-16 e l e16
17 862
4616 [R(int) ) 0.1310]
0/374
0.994
R1 ) 0.0609
wR2 ) 0.0795
R1 ) 0.1261
wR2 ) 0.0956
0.436/-0.380
1.85 to 23.27°
-14 e h e 14
-11 e k e 12
-14 e l e 13
7363
2508 [R(int) ) 0.0705]
0/192
1.073
R1 ) 0.0770
wR2 ) 0.1687
R1 ) 0.1250
wR2 ) 0.1898
0.291/-0.240
reflns collected
indep reflns
restraints/params
goodness of fit on F2
final R indices [I>2σ(I)]
R indices (all data)
largest diff peak/hole/e‚Å-3
Table 2. Selected Bond Lengths (Å) and Angles
(deg) in 2 (Ct ) center of the cyclopropenyl ring)
C(19)-C(21)
C(19)-C(20)
C(20)-C(21)
Ni(1)-Br(1)
Ni(1)-P(1)
Ni(1)-P(2)
Ni(1)-C(20)
1.425(8)
1.429(8)
1.432(8)
2.495(1)
2.254(2)
2.276(2)
1.970(6)
Ni(1)-C(21)
1.996(6)
2.016(6)
1.816
117.06
120.34
114.97
104.69(7)
Ni(1)-C(19)
Ni(1)-Ct
Ct-Ni(1)-P(2)
Ct-Ni(1)-P(1)
Ct-Ni(1)-Br(1)
P(1)-Ni(1)-P(2)
Table 3. Selected Bond Lengths (Å) and Angles
(deg) in the 1,2-Diphospha-3,4,5-triphenyl-
cyclopentadienide Anion in 3
P(1)-C(1)
1.771(4)
2.111(3)
1.408(5)
1.477(6)
1.499(9)
94.9(2)
P(1)-P(1)
C(1)-C(2)
C(1)-C(3)
C(2)-C(9)
C(1)-P(1)-P(1)
C(2)-C(1)-P(1)
C(1)-C(2)-C(1)
116.0(4)
118.1(6)
Figure 3. Three-dimensional packing of sodium bis-
(diglyme)-1,2-diphospha-3,4,5-triphenylcyclopentadienide
(3). Hydrogen atoms omitted for clarity; thermal ellipsoids
drawn at 50% probability.
Experimental Section
Equipment. All reactions and manipulations were carried
out under dry pure nitrogen in standard Schlenk apparatus.
All solvents were distilled from sodium/benzophenone and
stored under nitrogen before use. The NMR spectra were
recorded on a Bruker AVANCE DRX 400 or an MSL-400 (1H
400 MHz, 31P 121.7 MHz, 13C 100.6 MHz). SiMe4 was used as
(2) and 261783 (3) 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: (+44) 1223-336-033; or
deposit@ccdc.cam.uk).
1
internal reference for H and 13C NMR chemical shifts, and
85% H3PO4 as external reference for 31P.
X-ray Analyses. Data were collected with a Siemens CCD
(SMART) diffractometer (ω-scans). Data reduction was per-
formed with SAINT. Empirical absorption correction was
performed using the program SADABS. The structures were
solved by direct methods, and non-hydrogen atoms were
refined anisotropically (SHELX97). All H atoms were calcu-
lated on idealized positions and refined isotropically. Pictures
were generated with ORTEP3 for Windows.18 CCDC 261784
(18) (a) SMART: Area-Detector Software Package; Siemens Indus-
trial Automation, Inc.: Madison, WI, 1993. (b) SAINT: Area-Detector
Integration Software. Version 6.01; Siemens Industrial Automation,
Inc.: Madison, WI, 1999. (c) Sheldrick, G. M. SADABS, Program for
Scaling and Correction of Area-detector Data; Go¨ttingen, 1997. (d)
SHELX97 [Includes SHELXS97, SHELXL97]: Sheldrick, G. M.
SHELX97. Programs for Crystal Structure Analysis (Release 97-2);
University of Go¨ttingen: Germany, 1997. (e) ORTEP3 for Windows:
Farrugia, L. J. J. Appl. Crystallogr. 1997, 30, 565.

2236 Organometallics, Vol. 24, No. 9, 2005
Miluykov et al.
Synthesis. PMe2Ph,19 [Cp*NiBr(PPh3)],10 [Ni(cod)2] (cod )
1,5-cyclooctadiene),20 and (Ph3C3)Br21 were prepared according
to literature procedures.
C3Ph3). 31P NMR (C6D6): δ -6.0 (s). Anal. Calcd for C37H37-
BrNiP2 (682.23): C, 65.14; H, 5.47; P, 9.08. Found: C, 65.51;
H, 5.41; P, 9.27.
Sodium Pentaphosphacyclopentadienide, NaP5.22
A
Sodium Bis(diglyme)-1,2-diphospha-3,4,5-triphenylcy-
clopentadienide (3). A solution of 2 (1.36 g, 1.99 mmol) in
THF (20 mL) was added to a solution of NaP5 in diglyme (5 ×
10-2 M, 40 mL). The reaction mixture was stirred for 6 h at
room temperature. The solvent was evaporated and the residue
extracted three times with 50 mL of toluene. The toluene
solution was concentrated (10 mL), and then hexane (50 mL)
was added. The resulting precipitate was isolated by filtration
and washed with hexane. Yield: 0.72 g (59%) of 3 as light
brown powder. Mp: 125 °C (dec). Crystals suitable for X-ray
analysis were grown from toluene at -30 °C. 1H NMR (thf-
mixture of white phosphorus (2.04 g, 16 mmol), sodium (0.76
g, 33 mmol), and dibenzo-18-crown-6 (20 mg, 0.055 mmol) in
diglyme (40 mL) was refluxed for 6 h. After cooling, the
precipitate was filtered off and the solution was used for
further reactions without additional purification. The NaP5
concentration of this solution was determined by 31P NMR
spectroscopy by comparing the intensity of the signal of NaP5
with that of an internal standard (1.0 M solution of Ph4PCl in
THF). 31P NMR (C6D6): δ 469 (s).
Bis(dimethylphenylphosphine)triphenylcyclopropen-
ylnickel(II) Bromide (2). A solution of PMe2Ph (0.56 mL,
0.54 g, 3.92 mmol) in THF (10 mL) was added at -70 °C to a
solution of [Ni(cod)2] (0.54 g, 1.96 mmol) in THF (50 mL). After
stirring for 1 h at -70 °C (Ph3C3)Br (0.71 g, 2.00 mmol) was
added and the reaction mixture was stirred for 12 h at room
temperature. The mixture was filtered, the solvent evaporated,
and the residue dissolved in toluene (10 mL). Hexane (50 mL)
was added, and the resulting red precipitate was isolated by
filtration, washed three times with cold hexane, and dried in
vacuo. Yield: 0.93 g (69.5%) of 2 as red-brown powder. Mp:
157 °C (dec). Crystals suitable for X-ray analysis were grown
3
d8): δ 3.15 (s, 12H, MeO), 3.30 (t, 8H, JHH ) 5.1 Hz, OCH2),
3.38 (t, 8H, 3JHH ) 5.1 Hz, OCH2), 6.63 (t, 2H, 3JHH ) 7.3 Hz,
p-CH in Ph), 6.75 (br s, 9H, Ph), 6.93 (br d, 4H, 3JHH ) 7.3 Hz,
o-CH in Ph). 13C NMR (thf-d8): δ 58.07 (s, MeO), 69.69 (s,
OCH2), 71.39 (s, OCH2), 121.77 (s, m-C in Ph), 122.96 (s, m-C
in Ph), 125.91 (s, p-C in Ph), 126.20 (s, p-C in Ph), 129.73 (t,
2JPC ) 4.9 Hz, ipso-C in Ph), 131.93 (s, ipso-C in Ph), 143.88
2
(s, o-C in Ph), 144.27 (s, o-C in Ph), 147.02 (t, JPC ) 8.9 Hz,
1
C-Ph), 161.61 (t, JPC ) 28.5 Hz, C-Ph). 31P NMR (thf-d8): δ
190.0 (s). Anal. Calcd for C33H43NaO6P2 (620.60): C, 63.86; H,
6.98; P, 9.98. Found: C, 64.1; H, 7.04; P, 9.57.
1
2
from toluene at -30 °C. H NMR (C6D6): δ 1.3 (d, 12 H, JPH
) 5.7 Hz, Me), 6.8-7.2 (m, 25 H, Ph). 13C NMR (thf-d8): δ
22.03 (d, JPC ) 12.0 Hz, PMe), 124.91 (s, m-C in Ph), 126.50
Acknowledgment. The authors thank the Deutsche
Forschungsgemeinschaft (436RUS 113/760/0-1) and
RFBR (04-03-04102) for financial support of this work.
A.K. thanks the DAAD (A03/17532) for a Leonhard-
Euler grant.
1
(s, m-C in Ph), 127.67 (s, p-C in Ph), 127.78 (s, p-C in Ph),
127.91 (d, 1JPC ) 11.6 Hz, ipso-C in PPh), 128.22 (s, ipso-C in
Ph), 129.01 (s, o-C in Ph), 130.19 (s, o-C in Ph), 133.66 (s, C in
(19) Bartlett, P. D.; Meguerian, G. J. Am. Chem. Soc. 1956, 78,
Supporting Information Available: Crystallographic
details, including lists of positional parameters, thermal
displacement parameters, bond lengths, and bond angles, for
2 and 3. This material is available free of charge via the
Internet at http://pubs.acs.org.
3710-3715.
(20) Krysan, D. J.; Mackenzie, P. B. J. Org. Chem. 1990, 55, 4229-
4230.
(21) Breslow, R.; Won Chang, H. J. Am. Chem. Soc. 1961, 83, 2367-
2375.
(22) Miluykov, V. A.; Sinyashin, O. G. Russian Patent N 2178385,
2002.
OM050078U