Synthesis and characterization of some new organometallic complexes obtained by the reaction of bis(anilino)phosphine oxide with TiCl4 and Cp2ZrCl2

Article abstract of DOI:10.1007/s13738-012-0133-0

The bis(anilino)phosphine oxide (PhNH)₂P(O)H as a ligand reacts directly with zirconocene dichloride CP₂ZrCl₂ to afford H(PhNH)P[(NPh)OZr(Cp)₂Cl] (1), while in the presence of triethylamine as a base the ligand is deprotonated and H(O)P[(NPh)₂Zr(Cp) ₂] (2) is isolated in a very good yield. When the ligand is treated with TiCl₄, however, the diligand complex Cl₃TiO(NPh) PH(NPh)PHO(Nph)TiCl₃ (3) is separated in high yield. These new compounds have been fully characterized by FT-IR, UV-Vis spectrophotometry and multi-nuclear (¹H, ³¹P) NMR spectroscopy and elemental analysis as well as XRF analysis of SEM images.

Full text of DOI:10.1007/s13738-012-0133-0

J IRAN CHEM SOC (2013) 10:131–134
DOI 10.1007/s13738-012-0133-0
ORIGINAL PAPER
Synthesis and characterization of some new organometallic
complexes obtained by the reaction of bis(anilino)phosphine
oxide with TiCl4 and Cp2ZrCl2
•
Abbas Tarassoli Mohammad Kooti
•
Homa Javadi
Received: 29 March 2012 / Accepted: 20 June 2012 / Published online: 10 July 2012
Ó Iranian Chemical Society 2012
Abstract The bis(anilino)phosphine oxide (PhNH)2P(O)H
as a ligand reacts directly with zirconocene dichloride
CP2ZrCl2 to afford H(PhNH)P[(NPh)OZr(Cp)2Cl] (1),
while in the presence of triethylamine as a base the ligand
is deprotonated and H(O)P[(NPh)2Zr(Cp)2] (2) is isolated
in a very good yield. When the ligand is treated with TiCl4,
however, the diligand complex Cl3TiO(NPh)PH(NPh)-
PHO(Nph)TiCl3 (3) is separated in high yield. These new
compounds have been fully characterized by FT-IR, UV–Vis
spectrophotometry and multi-nuclear (1H, 31P) NMR spec-
troscopy and elemental analysis as well as XRF analysis of
SEM images.
cases the reaction could be carried out straightforward even
in the absence of a base [7–9]. Up to date, a considerable
number of organometallic compounds have been prepared
using these ligands such as bis(anillino)phosphine oxide [10]
and many of them have been considered as potential catalyst
precursors for olefin polymerization [1, 8]. The synthesis and
X-ray structural determination of selected (amino)-or (ani-
lino)phosphine molybdenum carbonyls have also been
extensively studied [11–13]. Recently, group IVB metal
complexes with bis(amido)cyclodiphosph(V)azane ligands
have attracted special attention as a modern generation
of early-transition metal-based-polymerization catalyst.
Therefore, in this research work, the synthesis of organo-
metallic compounds H(PhNH)P[(NPh)OZr(Cp)2Cl] (1),
H(O)P[(NPh)2Zr(Cp)2] (2) and Cl3TiO(NPh)PH (NPh)
PHO(NPh)TiCl3 (3) are reported, which are prepared from
the reaction of bis(anilino)phosphine oxide as a ligand with
TiCl4 or Cp2ZrCl2 at different experimental conditions.
Although a variety of phosphazane systems are known, the
linked Zr–Cp complexes are among the few and rare
examples of commercially exploited catalysts [14]. The
coordination behavior of this ligand with silicon, tin, zinc
and titanocene dichloride derivatives has already been
reported by this research group [15–18]. The present inves-
tigation has expanded and developed the coordination
chemistry of group IVB metals phosphazane complexes.
Keywords Aminophosphine Á Zirconocene dichloride Á
Bis(anilino)phosphine oxide Á Coordination chemistry
Introduction
Phosph(III/V)azane derivatives are now being widely
employed as ligands in the synthesis of metallic complexes
of early-transition metals [1, 2]. Such ligands usually bear N,
O and P active sites as hard and soft centers and N–H bonds’
functionality. Therefore, they are very useful starting mate-
rials in forming various coordination complexes with some
main groups and transition metals in which they act as a
monodentate or bidentate ligand [3–6]. In most synthetic
routes, the Phosph(III/V)azanes act as an anionic ligand, in
the presence of n-BuLi or a base such as triethylamine, which
abstracts hydrogen from N–H bonds. However, in some
Experimental
Apparatus and materials
A. Tarassoli (&) Á M. Kooti Á H. Javadi
Department of Chemistry, College of Science,
Shahid Chamran University, Ahvaz, Iran
e-mail: tarasoli@yahoo.com; tarassoli@scu.ac.ir
All experiments were performed under nitrogen using stan-
dard Schlenk techniques. Tetrahydrofuran was treated with
KOH and freshly distilled twice from sodium before use.
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Toluene and n-hexane weretreated with calciumchloride and
distilled over sodium before use. Aniline was dried over
magnesium sulfate, distilled at reduced pressure and stored
over it. Triethylamine was distilled over magnesium sulfate
and stored over it. Phosphorus trichloride and titanium tet-
rachloride were used as purchased from Merck Co. The
bis(anillino)phosphine oxide was prepared by previously
reported procedures [10, 15]. NMR spectra were recorded on
a Bruker Avance 500 and 400 MHz at ambient temperature.
1H NMR (500.13 and 400.13 MHz) spectra were recorded
using DMSO as a solvent and TMS as an external standard.
31P NMR spectra (202.45 and 161.97 MHz) were recorded
using DMSO as a solvent and referenced to external H3PO4
(85 %). IR spectra were measured on a Bomen FT-IR spec-
trophotometer. Elemental analysis(C, H, N) was performed
by the Department of Chemistry, College of Sciences Shiraz
University, Shiraz, Iran. The Zr and Ti contents were deter-
mined by XRF analysis of SEM images for compounds (1),
(2) and (3), respectively, and was performed by Scanning
Electron Microscopy (SEM) model LEO 1455-VP in Central
Laboratory, Shahid Chamran University, Ahvaz, Iran. The
chloride contents for (1) and (3) were measured by potenti-
ometric titration (argentometry).
zirconium compound Cp2ZrCl2 (0.292 g, 1 mmol) which
was already dissolved in 30 mL of dry toluene was slowly
added. Then (PhNH)2P(O)H (0.232 g, 1 mmol) in 50 mL of
dry toluene was dropwisely added into the flask. The reaction
was carried out under N2 at room temperature. The bright-
yellow reaction mixture was stirred at 75 °C for 1 day, then
cooled to 0 °C and filtered through a medium porosity frit to
remove triethylammonium hydrochloride. The resulting
bright-yellow filtrate was concentrated in vacuo and kept at
-12 °C for several days until to afford a solid product. The
product was washed with cold toluene and dried under vac-
uum for 24-h yield 75 % m.p. 140–142 °C (dec). IR (KBr,
cm-1): 2,354 (P–H), 1,172 (P=O), 3,422 (C–H in Cp), 1,277
(C–N), 909.5 (P–N), 1,444 (C–C in Cp). UV–Vis (DMSO,
nm) kmax 478. 1H NMR (25 °C, DMSO-d6, ppm): 7.11–6.34
(m, 20H, Ph and Cp) and 6.75 (d, JPH = 498.7 Hz, 1H, P–H).
31p {1H} NMR (25 °C, DMSO-d6, ppm): -4.7 (singlet).
Anal. Calcd. for C22H21PON2Zr (%): C, 58.48; H, 4.7; N,
6.21. Found (%): C, 58.20; H, 4.86; N, 5.59. Anal. cald. for
C22H21PON2Zr (%): Zr, 20.22; P, 6.87; O, 3.55. Found (XRF
analysis of SEM Images) (%): Zr, 20.81; P, 6.83; O, 3.49.
Synthesis of Cl3TiO(NPh)PH(NPh)PHO(NPh)TiCl3 (3)
Synthesis of H(PhNH)P[(NPh)OZr(Cp)2Cl] (1)
A two-neck 100-mL round bottom flask, equipped with
inlet, stir bar and dropping funnel under N2 at RT was
charged with THF (30 mL), n-hexane (10 mL), Et3N
(2 mmol, 0.3 mL) and TiCl4 (1.03 mL from a stock solu-
tion). To the cooled (0 °C) flask was added dropwise a
solution of (PhNH)2P(O)H (0.232 g, 1 mmol) dissolved in
20 mL mixture of THF: n-hexane. The obtained dark-
brown suspension gradually changed to orange. This mix-
ture was allowed to warm slowly up to room temperature
and stirred for 12 h. Then, it was filtered through a medium
porosity frit and the resulting orange filtrate was concen-
trated in vacuo until an orange product was obtained yield
78 %, m.p. 214–218 °C (dec). IR (KBr, cm-1): 2,358
(P–H), 3,402 (C–H, Ph), 1,172 (P=O), 744–682 (Ph), 925
In a 100-mL two-necked flask, equipped with stir bar, inlet
and dropping funnel which containing 30 mL of dry toluene,
Cp2ZrCl2 (0.292 g, 1 mmol) was dissolved at25 °C under N2
atmosphere. Then, (PhNH)2P(O)H (0.232 g, 1 mmol) which
was dissolved in 50 mL of dry toluenewas dropwisely added.
The reaction mixture was stirred at 75 °C for 24 h, then
cooled to 0 °C and filtered through a medium—porosity frit.
The bright-yellow filtrate was concentrated in vacuo and kept
at -12 °C for 3 days. The obtained orange solid product was
washed with cold toluene and dried in vacuo for 24-h yield
75 %, m.p. 128-130 °C (dec). IR (KBr, cm-1): 3,331 (C–H,
Ph), 2,289 (P–H), 1,219 (P=O), 3,098–2,904 (P–N),
1,494–1,596 (C=C, Ph), 1,077–1,015 (C–H, Ph). UV–Vis
(DMSO, nm) kmax 485. 1H NMR (25 °C, DMSO-d6, ppm):
7.40–7.06 (m, 20H, Ph and Cp), 9.88 (br, N–H), 7.40
1
(P–N), cm-1. UV–Vis (DMSO, nm) kmax 487. H NMR
(25 °C, DMSO-d6, ppm): 7.18(d, JPH = 571.6 Hz, 2H,
P–H) 7.05–7.41 (m, 15H, Ph). 31p {1H} NMR (25 °C,
DMSO-d6, ppm): 12.9 (singlet). Anal. Calcd. for
C18H17P2O2N3Ti2Cl6 (%): C, 31.86; H, 2.53; N, 6.20.
Found (%): C, 31.58; H, 2.67; N, 6.31. Anal. Calcd. for
C18H17P2O2N3Ti2Cl6 (%): Ti, 14.13; P, 9.14; O, 4.72; Cl,
31.42. Found (XRF analysis of SEM Images) (%): Ti,
14.29; P, 9.08; O, 4.57; Cl, 31.68.
1
(d, JPH = 503.5 Hz, 1H, P–H). 31P {1H}NMR (25 °C,
DMSO-d6, ppm): 1.2 (singlet).
Anal. calcd. for C22H22N2OPClZr (%): C, 54.11; H,
4.55; N,5.74. Found (%): C, 53.84; H, 4.46; N, 5.53. Anal.
calcd. (%) for C22H22N2OPClZr: Zr, 18.69; P, 6.35; O,
3.28; Cl, 7.28. Found (XRF analysis of SEM Images) (%):
Zr, 18.75; P, 6.57; O, 3.33; Cl, 7.47.
Synthesis of H(O)P[(NPh)2 Zr(Cp)2] (2)
Results and discussion
In a 100-mL two-necked flask, equipped with stir bar, inlet
and dropping funnel containing Et3N (0.3 mL, 2 mmol), the
The bis(anilino)phosphine oxide (PhNH)2P(O)H was pre-
pared according to the previously reported procedures
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J IRAN CHEM SOC (2013) 10:131–134
133
elemental analysis, multi-nuclear (1H, 31P) NMR, FT-IR
spectroscopy as well as XRF analysis of SEM images and
UV–Vis spectrophotometry. Reliable mass data were not
obtained for these complexes.
O
H
P
N
H
N
H
The IR spectroscopic data show that the ligand in com-
pounds (1) and (2) is bonded to Zr atoms through (O, N) and
(N, N), respectively, and in compound (3) is bonded to Ti
atoms through (O, N), and there was no indication of the
presence of N–H bond in compounds (2) and (3). The P=O
stretching band of ligand in compound (1) shifted to the
higher frequency by almost 47 cm-1, due to p-delocalization
of electrons in the ring formed upon coordination to zirco-
nium [2, 10], but this band in compound (2) was almost
without variation, which indicates that this bond is not par-
ticipated in the coordination. The P–H stretching band of the
ligand in compound (1) is shifted 80 cm-1 to the lower fre-
quency, due to participation of P in the O–P–N moiety which
is chelated to Zr(IV) center through O and N. This band is
almost without change for new compounds (2) and (3).
Scheme 1 The bis(anilino) phosphine oxide ligand
[10, 15] and fully characterized before use as a phosp-
hazane ligand (Scheme 1).
On treating of the ligand with zirconocene dichloride
in 1:1 molar ratio in dry toluene, a new orange solid
H(PhNH)P[(NPh)OZr(Cp)2Cl] (1) was obtained in very
good yield (65 %). In this reaction, 1 mol of HCl was
eliminated and (O–Zr–N) bonds were formed. In a similar
manner, the reaction of the ligand with zirconocene
dichloride in the presence of triethylamine in (1:1:2 molar
ratio) and in dry toluene yielded the new zirconium
complex H(O)P[(NPh)2Zr(Cp)2] (2) as a pale-yellow
powder (75 %). Triethylamine acts as a base and HCl
acceptor and the reaction was proceeded via the elimi-
nation of 2 mol of triethylammonium hydrochloride to
form N–Zr bonds. The reaction of the ligand with TiCl4
in the presence of Et3N in 1:2:2 molar ratio, respectively,
in the mixture of dry solvents (THF-n-hexane 1:1)
afforded an orange powder, organometallic compound
formulated as Cl3TiO(NPh)PH (NPh)PHO(NPh)TiCl3 (3)
(yield 78 %) (Scheme 2).
1
In the H NMR spectrum of compound (1), N–H and
P–H resonances are observed with the appropriate relative
intensities at d 9.8 ppm (br, 1H) and d 7.40 ppm (d, 1H) for
N–H and P–H, respectively. The aromatic protons are
appeared in the region of d 7.40–7.06 ppm (m, 20H) with
1
JPH = 503.5 Hz. The HNMR spectra of (2) and (3) show
P–H protons at d 6.75 ppm (d, 1H) and at 7.18 ppm (d,
2H), for (2) and (3), respectively. JPH = 498.7 Hz for (2)
and 571.6 Hz for (3) are characteristic coupling constants
for these kind of compounds [4, 10, 18]. Aromatic protons
of (2) and (3) appear at d 7.1–6.34 ppm (m, 20H) and at d
7.41–7.05 ppm (m, 15H), respectively.
In the 31P{1H}NMR of (1), (2) and (3), only one signal
as a singlet is detected which proves the existence of just
one type of phosphorous atom and is consistent with the
proposed structures. These signals are slightly shifted to the
up field with respect to the free ligand (-4.87 ppm) [10],
which indicates that the ligand is coordinated to the metal.
The reaction was proceeded via the precipitation of
2 mol of Et3NHCl and then dimerization was occurred
together with the elimination of 1 mol of aniline. The
newly obtained compounds were fully characterized by
Ph
H
O
H
Cp
Cp
N
Ph
N
O
P
Zr
P
Zr(Cp)2Cl
N
H
N
Ph
Conclusion
Ph
(1)
(2)
In the present investigation, three new titanium and zir-
conium complexes (1–3) are synthesized from the reaction
of bis(anilino)phosphine oxide with TiCl4 and Cp2ZrCl2 at
various experimental conditions and fully characterized.
The results indicate that the phosphazene ligand shows
different coordination preferences with Ti and Zr in the
formation of monomeric or dimeric structures. Finally, it
seems that the unique feature of these compounds causes
them to be applicable in the field of commercial catalysis,
material research and medicine which are practically
unexplored to date. Studies of these applications could be
an interesting subject for future investigations.
Ph
N
Cl
Cl
Cl
Cl
O
O
N
P
Ti
P
Cl
Cl
Ti
N
HH
Ph
Ph
(3)
Scheme 2 The structures of the new compound (1–3)
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J IRAN CHEM SOC (2013) 10:131–134
Acknowledgments The authors wish to thank Shahid Chamran
University Research Council, Ahvaz, Iran for financial support of this
project (Grant 1391).
9. D.F. Moser, L. Grocholl, L. Stahl, R.J. Staples, J. Chem. Soc.
Dalton Trans. 1402 (2003)
10. M.L. Thompson, R.C. Haltiwanger, A. Tarassoli, D.E. Coons,
A.D. Norman, Inorg. Chem. 21, 1287 (1982)
11. H. Chen, A. Tarassoli, V.S. Allured, R.C. Haltiwanger, A.D.
Norman, J. Organomet. Chem. 306, C19 (1986)
References
12. A. Tarassoli, H. Chen, V.S. Allured, T.G. Hill, R.C. Haltiwanger,
M.L. Thompson, A.D. Norman, Inorg. Chem. 25, 3541 (1986)
13. A. Tarassoli, H. Chen, M.L. Thompson, V.S. Allured, R.C.
Haltiwanger, A.D. Norman, Inorg. Chem. 25, 4152 (1986)
14. V.C. Gibson, S.K. Spitzmesser, Chem. Rev. 103, 283 (2003)
15. A. Tarassoli, G. Emami, Z. Khodamoradpur, Sulfur Silicon Relat.
Elem. 182, 2497 (2007)
1. M. Alajarin, C. Lopez-Leonardo, P.L. lamas-Lorente, Top Curr.
Chem. 250, 77 (2005)
2. D.F. Moser, C.J. Carrow, L. Stahl, R.J. Staples, J. Chem. Soc.
Dalton Trans. 1246 (2001)
3. M. Witt, H.W. Roesky, Chem. Rev. 94, 1163 (1994)
4. A. Tarassoli, L. Ezzedinloo, Phosphorus Sulfur Silicon Relat.
Elem. 183, 3013 (2008)
16. A. Tarassoli, Z. Khodamoradpur, Sulfur Silicon Relat. Elem. 181,
1675 (2006)
5. L. Grocholl, L. Stahl, R.J. Staples, Chem. Commun. 1465 (1997)
6. T.Q. Ly, J.D. Woollins, Coord. Chem. Rev. 176, 451 (1998)
¨
7. K.V. Axenov, M. Klinga, M. Leskela, V. Kotov, T. Repo, Eur.
J. Inorg. Chem. 4702 (2004)
17. A. Tarassoli, Z. Khodamoradpur, Phosphorus Sulfur Silicon
Relat. Elem. 180, 527 (2005)
18. A. Tarassoli, S. Hojatpanah, J. Coord. Chem. 64, 2028 (2011)
8. K.V. Axenov, V.V. Kotov, M. Klinga, M. Leskela, T. Repo, Eur.
J. Inorg. Chem. 695–706 (2004)
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