Cyclometallaphosphazene complexes of titanium(IV)

Article abstract of DOI:10.1080/15533170701674868

Cyclometallacyclophosphazene complexes of titanium(IV) corresponding to [{N(PPh2NR)2}nTiCl4-n], [{N(PPh2NR)2}nTiCl2-n (OPri)2], and [{N(PPh2NR)2}n(OPri) 2-n](R=Ph or SiMe3, G=CH2CH2, n=1 or 2) have been synthesized under anhydrous and inert conditions by the reaction of acyclic bis-silylated phosphazene ligand (A), [HN(PPh2NSiMe3)2], or bis-phenylated phosphazene ligand (B), [HN(PPh2NPh)2] with TiCl4, TiCl2(OPri)2 or (OPri)2 in 1:1 and 2:1 molar ratios. These titanatriazadiphosphorines were characterized by elemental analyses (C, H, N, Cl and Ti), molecular weight determination, and spectral studies including IR and NMR (1H, 13C, and 31P), which have indicated monomeric nature of the complexes and bidentate mode of bonding by phosphazene moiety leading to a trigonal bipyramidal and octahedral geometries around the titanium atom in 5 and 6 coordination numbers.

Full text of DOI:10.1080/15533170701674868

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Cyclometallaphosphazene Complexes of Titanium(IV)
Yash Paul a , Suresh Magotra a & Sushil K. Pandey a
a Department of Chemistry , University of Jammu , Jammu, India
Published online: 06 Nov 2007.
To cite this article: Yash Paul , Suresh Magotra & Sushil K. Pandey (2007) Cyclometallaphosphazene Complexes of
Titanium(IV), Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 37:9, 705-711
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 37:705–711, 2007
Copyright # 2007 Taylor & Francis Group, LLC
ISSN: 1553-3174 print/1553-3182 online
DOI: 10.1080/15533170701674868
Cyclometallaphosphazene Complexes of Titanium(IV)
Yash Paul, Suresh Magotra, and Sushil K. Pandey
Department of Chemistry, University of Jammu, Jammu, India
most investigated phosphorus-nitrogen compound, particu-
Cyclometallacyclophosphazene complexes of titanium(IV) cor- larly, in view to its metathesis reactions with a wide variety
of nucleophiles.[1–5] Roesky et al. have synthesized several
heterometallacyclophosphazenes by using acyclic phospha-
responding to [fN(PPh2NR)2gnTiCl4-n], [fN(PPh2NR)2gnTiCl2-n
(OPri)2], and [fN(PPh2NR)2gn
(OPri)2-n](R 5 Ph or SiMe3,
zene ligands, which have depicted rather interesting features
both in view of their structure and utility.[6–8] Phosphazene
derivatives are well known as potential precursors in the field
of ceramic and inorganic polymer chemistry.[1,2,8,9] Phospha-
zene unit, N55PR2, is isoelectronic to the siloxane group,
O55SiR2, that have a broad range of applications as fluids,
greases, resins, elastomers and emulsions.[10] Since, the
cyclic titanaisiloxanes might act as precursor for high-tempera-
ture polymer, the thermal degradation of polytitanodimethylsi-
loxanes has been explored in detail.[10] Literature survey
revealed that transition metals as well as main group
elements have been incorporated into the P–N ring system,
which resulted the formation of numerous interesting phospha-
zene derivatives.[11] We have also investigated the phospha-
zene chemistry during the past few years and incorporated
several elements into the P–N ring skeleton.[12–17] It is
observed that there is paucity of work on the chemistry of tita-
nium(IV) cyclophosphazenes. Titanium(IV) compounds are
known to possess significant antiproliferative effects toward
some tumors and leukemia.[18,19] The interest in the compounds
of titanium is due to their activity as catalysts in the polymeriz-
ation of olefins i.e., its pre-eminence in the Ziegler-Natta
catalyst.[20,21] In view of the above and knowing that TiCl4,
G 5 CH2CH2, n51 or 2) have been synthesized under anhydrous
and inert conditions by the reaction of acyclic bis-silylated
phosphazene ligand (A), [HN(PPh2NSiMe3)2], or bis-phenylated
phosphazene ligand (B), [HN(PPh2NPh)2] with TiCl4,
TiCl2(OPri)2 or
(OPri)2 in 1:1 and 2:1 molar ratios. These
titanatriazadiphosphorines were characterized by elemental
analyses (C, H, N, Cl and Ti), molecular weight determination,
and spectral studies including IR and NMR (1H, 13C, and 31P),
which have indicated monomeric nature of the complexes and
bidentate mode of bonding by phosphazene moiety leading to a
trigonal bipyramidal and octahedral geometries around the
titanium atom in 5 and 6 coordination numbers.
Keywords metallatriazadiphosphorines, heterometallacyclophos-
phazenes, cyclotitanaphosphazenes, bis-silylated and
bis-phenylated phosphazenes
INTRODUCTION
Phosphazene chemistry has experienced a rapid growth
during the past decade, stimulated by the wide interest into
its fundamental as well as technological aspects, and perhaps
represents next to the silicones which are the most intensively
investigated inorganic non-metallic field. The 6-membered
cyclotriazaphosphazene, (NPCl2)3, (2,2,4,4,6,6-hexasubsti-
tuted-1,3,5,2l5,4l5,6l5-triazatriphosphorines), is by far the
TiCl2(OPri)2, and OCH2CH2OTi(OPri)2 are good
synthones for preparing titanium(IV) complexes, it was
thought worthy to incorporate titanium into the P–N–P ring
system. So, we report herein on the synthesis and characteriz-
ation of the cyclotitanaphosphazenes corresponding to
[fN(PPh2NR)2gnTiCl4-n], [fN(PPh2NR)2gnTiCl2-n(OPri)2] and
Received 18 September 2006; accepted 9 May 2007.
Dedicated to Professor Dr. Herbert W. Roesky on his 70th
birthday.
We gratefully acknowledge financial support from the Department
of Science and Technology, New Delhi. The authors are thankful to
the Regional Research Laboratory, Jammu and Central Drug
Research Institute, Lucknow for spectral studies. Yash Paul is
thankful to Department of Science and Technology, New Delhi for
Junior Research Fellowship.
[fN(PPh2NR)2gn
(OPri)2-n].
EXPERIMENTAL
Materials and Methods
Address correspondence to S. K. Pandey, Department of Chem-
istry, University of Jammu, Baba Sahib Ambedkar Road, Jammu
180006 (J & K), India. E-mail: kpsushil@rediffmail.com
Standard Schlenk techniques, N2 atmosphere and vacuum
line were used to carry out all manipulations. All solvents
705

706
Y. PAUL, S. MAGOTRA, AND S. K. PANDEY
were distilled over sodium metal and degassed before use. The contents was changed from light yellow to pale yellow and pre-
bis-silylated phosphazene ligand (A), [HN(PPh2NSiMe3)2] and cipitation of triethylamine hydrochloride, Et3NHCl, took place.
bis-phenylated phosphazene ligand (B), [HN(PPhNPh)2] The precipitates of triethylamine hydrochloride were filtered off
were prepared by literature method.[15,22] High purity TiCl4 by using an alkoxy funnel fitted with a G-4 sintered disc and the
was procured commercially (Aldrich) and used as received. excess of solvent was removed from the filtrate under reduced
pressure, which yielded the compound [N(PPh2NSiMe3)2-
TiCl2(OPri)2 and
(OPri)2 were prepared in the
TiCl(OPri)2] (5) as yellow solid in 95% yield. All other analo-
gous compounds (6–8) were prepared by a similar method,
and their synthetic and analytical data are given in Table 1.
laboratory. Dichlorodiisopropoxytitanium(IV), TiCl2(OPri)2,
was prepared by 1:2 molar reaction of titaniumtetrachloride
with isoprapanol. Cycloethylenedioxydiisopropoxytitanium(IV),
Synthesis of [fN(PPh2NR)2gn
SiMe3, n 5 1 or 2)
A weighed amount of
(OPri)2-n](R 5 Ph or
(OPri)2, was synthesized by the reaction of
TiCl2(OPri)2 with ethylene glycol in 1:1 molar ratio in the
presence of triethylamine. Elemental analyses (C, H and N)
were carried out in the Micro-analytical lab at Regional
Research laboratory, Jammu. Titanium was estimated gravime-
trically as TiO2. Chlorine was estimated by Volhard’s method
whereas isopropoxy group was determined by potassium
dichromate oxidation method. Molecular weights were deter-
mined cryoscopically in freezing benzene. IR spectra were
recorded in KBr mulls in the range 4000–200 cm21 on a
(OPri)2 (0.41 g, 1.82 mmol)
in 30 ml toluene was added dropwise to a toluene solution
(ꢀ30 ml) of 1.02 g (1.82 mmol) of bis-silylated phosphazene
ligand, [HN(PPh2NSiMe3)2], at room temperature. The
contents of the reaction mixture were first stirred at the same
temperature for 1 hour and subsequently refluxed for 6 hours
under ratio head, the color of the contents was changed to pale
yellow. The isopropanol, formed during the course of reaction,
was removed azeotropically at the rate of one drop per
minute. The excess of solvent was removed under reduced
pressure and dried finally for 2 hours in vacuo, which yielded
1
Perkin-Elmer 377 spectrophotometer. The H, 13C, and 31P
NMR spectra were recorded on a Bruker DRX 300 (120 MHz)
spectrometer using TMS as the internal reference for 1H NMR
and 85% H3PO4 as an external reference for 31P NMR.
the compound [N(PPh2NSiMe3)2
(OPri)2] (9) as yellow
solid in 93% yield. All other analogous compounds (10–12)
were prepared by a similar method, and their synthetic and
analytical data are given in Table 1.
Synthesis of [fN(PPh2NR)2gnTiCl4-n] (R 5 Ph or SiMe3,
n 5 1 or 2)
A weighed amount (1.70 g, 3.04 mmol) of bis-silylated phos-
phazene ligand, [HN(PPh2NSiMe3)2], was dissolved in toluene
(ꢀ30 ml) in a round bottom flask and then 0.58 g (3.05 mmol)
of TiCl4 solution in toluene (ꢀ30 ml) alongwith equimolar
amount of triethylamine was added to it dropwise under ice-
cooled conditions. The contents were stirred at ice-cooled temp-
erature for ꢀ2 hours and subsequently at room temperature for
ꢀ2 hours, during this time the color of the reaction mixture was
turned from pale yellow to reddish. The precipitates of triethyl-
amine hydrochloride, Et3NHCl, were filtered off by using alkoxy
funnel fitted with a G-4 sintered disc and the excess of solvent
was removed from the filtrate under reduced pressure which
yielded the compound [N(PPh2NSiMe3)2TiCl3] (1) as a
reddish solid in 93% yield. All other analogous compounds
(2–4) were prepared by a similar method and their synthetic
and analytical data are given in Table 1.
RESULTS AND DISCUSSION
Acyclic bis-silylated phosphazene (A), [HN(PPh2NSiMe3)2],
and bis-phenylated phosphazene (B), [HN(PPh2NPh)2], ligands
are the new members of a fundamentally important class of
nitrogen containing chelating ligands and known to form M-N
bond with several transition as well as non-transition atoms.
The acyclic bis-silylated phosphazene (A) and bis-phenylated
phosphazene (B) ligands were reacted with titanium tetrachloride,
TiCl4, in 1:1 and 2:1 molar in presence of equimolar amount of
triethylamine under anhydrous and inert conditions, which
resulted the formation of compounds corresponding to [fN(PPh2
NR)2gnTiCl4-n] (R ¼ Ph or SiMe3, n ¼ 1 or 2) (1–4) as reddish
solid. These reactions were appeared to be quite facile as indicated
by immediate precipitation of triethylamine hydrochloride,
Et3NHCl, in both 1:1 and 1:2 molar reactions (Scheme 1).
The yellow-colored solid compounds corresponding to
formula [fN(PPh2NR)2gnTiCl2-n(OPri)2] (R ¼ Ph or SiMe3,
n ¼ 1 or 2) (5–8) have been isolated by the reaction of
Synthesis of [fN(PPh2NR)2gnTiCl2-n(OPri)2] (R 5 Ph or
SiMe3, n 5 1 or 2)
A toluene solution (ꢀ30 ml) of TiCl2(OPri)2 (0.50 g, acyclic bis-phenylated phosphazene, [HN(PPh2NPh)2], and
2.11 mmol) alongwith equimolar amount of triethylamine, bis-silylated phosphazene, [HN(PPh2NSiMe3)2], ligands with
Et3N, (0.26 ml, 2.11 mmol) was added dropwise with stirring dichlorodiisopropoxytitanium(IV), TiCl2(OPri)2, in 1:1 and
to a toluene solution (ꢀ30 ml) of 1.18 g (2.11 mmol) of bis-sily- 2:1 molar ratio in toluene and also in the presence of equimolar
lated phosphazene ligand, [HN(PPh2NSiMe3)2], at room temp- amount of triethylamine (Scheme 1). These reactions were
erature. The contents were stirred for 2 hours at room appeared to be rather sluggish, compared to the reactions
temperature and then refluxed for 3 hours. The color of the with TiCl4, as required refluxing for 4–6 hours.

TABLE 1
Synthetic and analytical data of cyclometallaphosphazene complexes of titanium(IV)
Analysis (%) found
(calcd.)
Reactants
[HN(PPh2NR)2]
TiX4 gm (mmol)
Molar
Ratio
(Ref.)
S.
no.
Yielda
(m.p.)b
M.W. found
(calcd.)
Product (Physical state)
Ti
Cl
C
H
N
1
2
3
4
5
6
1.70
(3.04l)
1.17
TiCl4 0.58
(3.05)
1:1
2:1
1:1
2:1
[N(PPh2NSiMe3)2TiCl3]
(Reddish solid)
93 (101) 711.1 (711.3)
6.76
14.94
50.59 5.43 (5.33) 5.72 (5.89)
(6.72) (14.91) (50.53)
94 (98) 1240.9 (1234.8) 3.89 58.90 5.76
(3.87) (5.47) (58.30)
6.34 14.67 59.68 4.26 (4.16) 6.02 (5.83)
(6.65) (14.66) (59.96)
95 (82) 1240.3 (1250.8) 3.73 5.87 69.73 4.31 (4.79) 6.83 (6.74)
(3.82) (5.67) (69.07)
6.45 4.69 56.38 6.39 (6.84) 5.09 (5.53)
(6.30) (4.67) (56.88)
TiCl4 0.20
(1.05)
[fN(PPh2NSiMe3)2g2TiCl2]
(Reddish solid)
6.73(6.15) 6.49 (6.80)
(2.09l)
1.73
TiCl4 0.58
(3.05)
[N(PPh2NPh)2TiCl3]
(Reddish solid)
92 (117) 730.5 (719.3)
(3.05)
1.18
TiCl4 0.20
(1.05)
[fN(PPh2NPh)2g2TiCl2]
(2.09)
1.18
(Reddish solid)
TiCl2(OPri)2 1:1 (4 h) [N(PPh2NSiMe3)2TiCl(OPri)2]
95 (88)
760.3 (759.3)
(2.07)
0.68
(1.21)
0.18 (1.04)
(yellow solid)
TiCl2(OPri)2 2:1 (6 h) [fN(PPh2NSiMe3)2g2Ti(OPri)2]
96 (94) 1290.5 (1281.8) 3.79
—
61.83 7.12 (7.02) 6.85 (6.55)
(61.78)
0.14
(0.60)
(yellow solid)
7
8
0.96
(1.69)
TiCl2(OPri)2 1:1 (4 h) [N(PPh2NPh)2TiCl(OPri)2]
95 (97)
92 (89)
780.4 (767.3)
730.2 (724.8)
6.24
(6.23) (4.62) (65.67)
4.63
65.47 5.47 (5.73) 5.51 (5.47)
0.40
(1.68)
(yellow solid)
1.53
(2.69)
TiCl2(OPri)2 2:1 (4 h) [N(PPh2NPh)2Ti(OPri)2]
3.69
(3.68)
—
—
71.93 5.59 (5.57) 6.57 (6.47)
(72.11)
0.31
(1.30)
(yellow solid)
9
10
11
12
1.02
(1.82)
1:1 (6 h) [N(PPh2NSiMe3)2
(yellow solid)
(OPri)] 93 (107)
—
6.73
(6.60)
56.72 6.21 (6.36) 5.31 (5.60)
(56.84)
(OPri)2
0.41
(1.82)
(OPri)2
1.08
(1.93)
2:1 (6 h) [fN(PPh2NSiMe3)2g2
]
94 (120) 740.2 (732.8)
3.87
(3.91)
—
59.93 6.56 (6.46) 6.59 (6.78)
(60.10)
(yellow solid)
0.21
(0.87)
0.90
(1.58)
1:1 (6 h) [N(PPh2NP)2
(yellow solid)
(OPri)]
95 (123)
—
—
6.54
(6.61) (65.87)
65.71 5.58 (5.48) 5.59 (5.62)
(OPri)2
0.34
(1.58)
(OPri)2
1.65
(2.91)
2:1 (6 h) [fN(PPh2NPh)2g2
]
93 (132) 1240.3 (1239)
3.89
(3.86)
—
73.96 5.12 (5.10) 6.71 (6.69)
(74.64)
(yellow solid)
0.32
(1.41)
where G ¼ CH2CH2, X ¼ Cl, Cl2(OPri)2 or OGO(OPri).
aIn % age.
bIn 8C.

708
Y. PAUL, S. MAGOTRA, AND S. K. PANDEY
IR Spectra
The tentative assignments for important bands have been
made on the basis of literature reports.[7,8,11–14] The ring
formation in these complexes is responsible for the appearance
of some new bands, which are absent in the spectra of the
parent ligands. The absorptions for n(P–N) bands were found
in the region 1284–1026 cm21, which is in agreement to the
symmetric nature of n(P–N–P) ring system. The disappearance
of a strong band for n(NH) at 3345 cm21 and the appearance of
new bands in the region 520–513 cm21 are suggestive of for-
mation of a Ti–N bond. The sharp bands of medium intensity
in the region 360–340 cm21 have been assigned to n(Ti–Cl) in
compounds (1–4) and the strong bands for n(P ¼ N) were
found in the region 1497–1437 cm21 with a slight shift of
60–40 cm21 toward the lower frequency region. A strong
band was also observed in the region 680–620 cm21, which
is attributed to the Ti–O bond (5–12). The relevant IR data
of these complexes are given in Table 2.
SCH. 1. Reactions of [HN(PPh2NR)2] with TiCl4, TiCl2(OPri)2 and
(OPri)2 (R ¼ Ph or SiMe3, G ¼ CH2CH2 and n ¼ 1 or 2).
The pale yellow-colored solid compounds [fN(PPh2NR)2gn
(9–12) were obtained when the acylic phospha-
zene ligands (A) or (B) were reacted with cycloethylenedioxy-
diisopropoxytitanium(IV),
(OPri)2 in 1:1 and 2:1
molar ratio in toluene. These reactions got completed on reflux-
ing for longer time and simultaneous azeotropic removal of
isopropanol.
These compounds were obtained with sufficient purity;
however, the compounds (1–8) were further purified by
washing with dried diethylether while the compounds (9–12)
were washed with dried n-hexane. These heterometallacyclo-
phosphazenes appeared to be moisture sensitive but can be
stored for long without any aging phenomenon under dried
atmosphere. Molecular weight determinations of these com-
pounds have indicated the monomeric nature. The elemental
analyses of these complexes, particularly C, H, N, Ti, Cl, and
determination of isopropoxy were found to be consistent with
their molecular compositions.
1H NMR Spectra
In the 1H NMR spectra of these complexes, the peak for the
NH proton in the range d 4.5–5.0 ppm (present in the parent
phosphazene ligands) was found absent, which indicates depro-
tonation of the ligand as a consequence of complexation to the
titanium atom. The phenyl protons due to PPh2 and NPh
groups in the complexes with the bis-phenylated ligand,
[HN(PPh2NPh)2], were found as two multiplets in the region
d 6.30–8.40 ppm and the phenyl protons due to PPh2 in
the complexes with the bis-silylated phosphazene ligand,
TABLE 2
IR data (cm21) of cyclometallaphosphazene complexes of titanium(IV)
n(P–N–P)
(Ring-vibrations)
S. no.
Compound
n(P ¼ N)
n(Ti-O)
n(Ti-N)
n(Ti-Cl)
1
2
3
4
5
6
7
8
[N(PPh2NSiMe3)2TiCl3]
[fN(PPh2NSiMe3)2g2TiCl2]
[N(PPh2NPh)2TiCl3]
1437, vs
1437, vs
1497, vs
1490, vs
1436, vs
1436, vs
1430, vs
1497, vs
1219–1026
1260–1026
1284–1120
1280–1115
1203–1026
1203–1026
1210–1120
1261–1119
—
—
513, s
513, s
518, s
350, m
360, m
360, m
340, m
330, m
—
—
—
[fN(PPh2NPh)2g2TiCl2]
520, vs
515, vs
514, s
[N(PPh2NSiMe3)2TiCl(OPri)2]
[fN(PPh2NSiMe3)2g2Ti(OPri)2]
[N(PPh2NPh)2TiCl(OPri)2]
[fN(PPh2NPh)2g2Ti(OPri)2]
620, s
693, s
685, s
692, s
515, vs
519, vs
330, m
—
9
10
11
12
[N(PPh2NSiMe3)2
[fN(PPh2NSiMe3)2g2
[N(PPh2NPh)2
(OPri)]
1440, vs
1420, vs
1430, vs
1420, vs
1260–1110
1230–1115
1240–1090
1200–1105
680, vs
640, vs
630, s
510, vs
520, vs
515, vs
510, vs
—
—
—
—
]
(OPri)]
[fN(PPh2NPh)2g2
]
620, vs
Where vs ¼ very strong, s ¼ strong and m ¼ medium.

CYCLOMETALLAPHOSPHAZENE COMPLEXES
709
[HN(PPh2NSiMe3)2], were found as a single multiplet in the group as well as OCH group. The chemical shift for the
region d 6.10–8.40 ppm. The chemical shift of the methyl methyl protons was found as doublet in the region d 0.75–
protons of SiMe3 was observed around d 0.12 ppm, showing 1.60 ppm, while a quartet was observed for OCH group in
no appreciable change in position compared to the parent phos- the region d 3.60–5.00 ppm. The chemical shift for OCH2
phazene moiety. The presence of isopropoxy group in the com- group of glycoxy moiety was observed in the region d 4.60–
1
plexes (5–9 and 11) was confirmed by the appearance of the 5.25 ppm. The H NMR spectral data of these compounds
chemical shift for the methyl protons of the isopropoxy are summarized in Table 3.
TABLE 3
1H and 31P NMR spectral data of cyclometallaphosphazene complexes of titanium(IV) in CDCl3 in d ppm
S. no.
1
Compound
1H chemical shift
31P chemical shift
[N(PPh2NSiMe3)2TiCl3]
0.12, s, 18H (SiMe3)
6.10–8.40, m, 20H (PPh2)
0.10, s, 36H (SiMe3)
15.04, s
2
3
4
5
[fN(PPh2NSiMe3)2g2TiCl2]
[N(PPh2NPh)2TiCl3]
16.40, s
14.37, s
15.34, s
16.19, s
6.30–8.40, m, 40H (PPh2)
6.50–6.90, m, 10H (NPh)
7.55–8.40, m, 20H (PPh2)
6.30–6.80, m, 20H (NPh)
7.35–8.20, m, 40H (PPh2)
0.12, s, 18H (SiMe3)
[fN(PPh2NPh)2g2TiCl2]
[N(PPh2NSiMe3)2TiCl(OPri)2]
0.90–1.40, d, 12H (CH3)
4.60–5.00, m, 2H (OCH)
6.50–8.25, m, 40H (PPh2)
0.13, s, 36H (SiMe3)
6
7
8
9
[fN(PPh2NSiMe3)2g2Ti(OPri)2]
[N(PPh2NPh)2TiCl(OPri)2]
[fN(PPh2NPh)2g2Ti(OPri)2]
15.17, s
14.08, s
15.06, s
19.89, s
0.90–1.40, d, 12H (CH3)
4.60–5.00, m, 2H (OCH)
6.50–8.25, m, 40H (PPh2)
0.75–1.60, d, 12H (CH3)
3.60–4.20, m, 2H (OCH)
6.20–6.95, m, 20H (NPh)
7.40–8.30, m, 40H (PPh2)
0.75–1.60, d, 12H (CH3)
3.60–4.20, m, 2H (OCH)
6.20–6.95, m, 20H (NPh)
7.40–8.30, m, 40H (PPh2)
0.12, s, 36H (SiMe3)
[N(PPh2NSiMe3)2
(OPri)]
0.85–1.80, d, 12H (CH3)
3.65–4.30, m, 2H (–OCH)
4.60–5.25, t, 4H (OCH2)
6.50–8.30, m, 40H (PPh2)
0.12, s, 36H (SiMe3)
10
11
[fN(PPh2NSiMe3)2g2
]
19.63, s
14.03, s
4.60–5.25, t, 4H (OCH2)
6.50–8.30, m, 40H (PPh2)
0.75-1.60, d, 12H (CH3)
3.60–4.20, m, 2H (OCH)
4.60–5.25, t, 4H (OCH2)
6.50–8.30, m, 40H (PPh2)
4.60-5.25, t, 4H (OCH2)
6.50–8.30, m; 40H (PPh2)
[N(PPh2NPh)2
(OPri)]
12
[fN(PPh2NPh)2g2
]
15.41, s
Where s ¼ singlet, d ¼ doublet, t ¼ triplet and m ¼ multiplet.

710
Y. PAUL, S. MAGOTRA, AND S. K. PANDEY
TABLE 4
13C NMR spectral data of cyclometallaphosphazene complexes of titanium(IV) in d ppm
S. no
Compound
CH3
Ph
CH3
OCH
1
2
3
4
5
6
7
8
[N(PPh2NSiMe3)2TiCl3]
[fN(PPh2NSiMe3)2g2TiCl2]
[N(PPh2NPh)2TiCl3]
3.5, s
3.6, s
3.9, s
3.8, s
3.8, s
3.7, s
3.5, s
3.9, s
120–139, m
123–138, m
120–140, m
122–138, m
120–140, m
122–140, m
120–140, m
120–138, m
—
—
—
—
—
—
—
—
[fN(PPh2NPh)2g2TiCl2]
[N(PPh2NSiMe3)2TiCl(OPri)2]
[fN(PPh2NSiMe3)2g2Ti(OPri)2]
[N(PPh2NPh)2TiCl(OPri)2]
[fN(PPh2NPh)2g2Ti(OPri)2]
25.5, s
22.5, s
26.5, s
27.9, s
45.5, m
44.5, m
45.7, m
44.5, m
9
10
11
12
[N(PPh2NSiMe3)2
[fN(PPh2NSiMe3)2g2
[N(PPh2NPh)2
(OPri)]
3.7, s
3.6, s
3.8, s
3.8, s
120–139, m
120–140, m
120–140, m
120–138, m
24.5, s
26.5, s
23.5, s
27.9, s
44.7, m
45.5, m
44.5, m
45.7, m
]
(OPri)]
[fN(PPh2NPh)2g2
]
Where s ¼ singlet and m ¼ multiplet.
13C NMR Spectra
31P NMR Spectra
In the 31P NMR spectra, only 1 singlet was observed in each
The 13C NMR spectra of these complexes do not show any
appreciable change in their chemical shift from the correspond- complex with a downfield shift of d 4–8 ppm compared to the
ing values of the parent acyclic phosphazene ligands. The parent acyclic bis-phenylated phosphazene ligand,
chemical shift of the methyl carbons of the trimethylsilyl [HN(PPh2NPh)2], and bis-silylated phosphazene ligand,
group was observed at d 3.8–3.9 ppm. The phenyl carbons [HN(PPh2NSiMe3)2]. The chemical shift in these compounds
occur as a multiplet in the region d 120–140 ppm. The occurs at d 15–16 ppm. This downfield shift may be attributed
chemical shift for the methyl carbons of the isoprpoxy group to the bidentate linkage of the phosphazene ligand. Further, the
was observed at d 25–30 ppm and for the OCH2 group was
observed in the region d 60–70 ppm. The appearance of the
chemical shift due to methyl carbon and the carbon of OCH2
group authenticate the insertion of titanium atom into the phos-
phazene ring (Table 4).
FIG. 3. Trigonal bipyramidal geometry of the complexes [N(PPh2NR)2
(OPri)] (G ¼ CH2CH2, R ¼ Ph or SiMe3).
FIG. 1. Trigonal bipyramidal geometry of the complexes [N(PPh2NR’)2-
TiCl3] (X and Y ¼ Cl) and [N(PPh2NR)2TiCl(OPri)2] (X ¼ OPri, Y ¼ Cl)
(where R ¼ Ph or SiMe3).
FIG. 4. Octahedral geometry of the complexes [fN(PPh2NR)2g2
FIG. 2. Octahedral geometry of the complexes [fN(PPh2NR)2g2TiCl2]
(X ¼ Cl) and [fN(PPh2NR)2g2Ti(OPri)2] (X ¼ OPri) (where R ¼ Ph or SiMe3).
] (where G ¼ CH2CH2, R ¼ Ph or SiMe3).

CYCLOMETALLAPHOSPHAZENE COMPLEXES
711
9. Wheeler, R. A.; Hoffmann, R.; Wangbo, M. H.; Albright, T. A.;
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occurrence of a singlet may be due to the equivalent nature of
the phosphorus nuclei in the molecule and also symmetric
nature of species. The 31P NMR spectra of these complexes
are summarized in Table 3.
10. Voronkov, M. G.; Maletina, E. A.; Roman, V. K. Heterosiloxanes;
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Structural Features
Our efforts to get suitable crystals for the single-crystal
X-ray analysis were not successful. Therefore, it is not
possible to predict the precise structure of these complexes.
However, on the basis of elemental analyses, molecular
weight determinations and spectroscopic studies like IR and
NMR (IR, 1H, 13C, and 31P) and in conjunction with the litera-
ture reports,[7,8,11–14,23–25] a trigonal bipyramidal geometry
around the titanium in the 5 coordination in the complexes
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of six membered ring complexes of zinc. Inorg. Chem. 1993,
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[N(PPh2NR)2TiCl3] (1 and 3) [N(PPh2NR)2
] (5
14. Pandey, S. K.; Paul, Y. Spirocyclic phosphazene complexes of
arsenic(III): synthesis and characterization. Phosph. Sulf. Silicon
2003, 178, 159–170.
and 7), and [N(PPh2NR)2TiOCH2CH2O(OPri)] (9 and 11)
may plausibly be assigned whereas an octahedral geometry
around the titanium in six coordination for the complexes
type [fN(PPh2NR)2TiCl2] (2 and 4), [fN(PPh2NR)2g2
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and 12) may be proposed in which the phosphazene moiety
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normaldruck-polathylene-verfahren. Angew. Chem. 1955, 67,
541–547.
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