Preparation of the First Examples of Ansa-Spiro Substituted Fluorophosphazenes and Their Structural Studies: Analysis of C-H···F-P Weak Interactions in Substituted Fluorophosphazenes

Article abstract of DOI:10.1021/ic034712c

The reactions of fluorophosphazenes, endo ansa FcCH₂P(S)(CH ₂O)₂[P(F)N]₂(F₂PN) (1) (Fc = ferrocenyl) and spiro [RCH₂P(S)(CH₂O) ₂PN](F₂PN)₂ (R = Fc (2), C₆H ₅ (3)], with dilithiated diols have been explored. The study resulted in the formation of the first examples of ansa-spiro substituted fluorinated cyclophosphazenes as well as a bisansa substituted fluorophosphazene. The bisansa compound {1,3-[FcCH₂P(S)(CH ₂O)₂]}{1,5-[CH₂(CH₂O) ₂]}N₃P₃F₂ (4) was found to be nongeminaly substituted with both the ansa rings in cis configuration, which is in stark contrast to the observations on cyclic chlorophosphazenes where geminal bisansa formation has been observed. The ansa-spiro compounds (5-7) underwent the ansa to spiro transformation leading to dispiro compounds in the presence of catalytic amounts of CsF at room temperature. Two of the ansa-spiro compounds, endo-{3,5-[FcCH₂P(S)-(CH₂O) ₂]}{1,1-[CH₂(CH₂O)₂]}N ₃P₃F₂ (5) and endo-{3,5-[FcCH ₂P(S)(CH₂O)₂]}{1,1-[FcCH ₂P(S)(CH₂O)₂]}N₃P₃F ₂ (6), were structurally characterized, and the crystal structures indicate boat-chair conformation as well as crown conformation for the eight-membered ansa rings. Weak C-H···F-P interactions observed in the crystal structures of the ansa-spiro substituted fluorophosphazene derivatives have been analyzed and compared with C-H···F-P interactions of other fluorinated phosphazenes and thionyl phosphazenes.

Full text of DOI:10.1021/ic034712c

Inorg. Chem. 2003, 42, 7535−7543
Preparation of the First Examples of Ansa−Spiro Substituted
Fluorophosphazenes and Their Structural Studies: Analysis of
C−H‚‚‚F−P Weak Interactions in Substituted Fluorophosphazenes
,‡
K. Muralidharan† and Anil J. Elias*
Department of Chemistry, Indian Institute of Technology, Kanpur 208 016, India, and Department
of Chemistry, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110 016, India
Received June 21, 2003
The reactions of fluorophosphazenes, endo ansa FcCH P(S)(CH O)2[P(F)N]2(F PN) (1) (Fc ) ferrocenyl) and spiro
2
2
2
[RCH P(S)(CH O)2PN](F PN)2 (R ) Fc (2), C H (3)], with dilithiated diols have been explored. The study resulted
2
2
2
6 5
in the formation of the first examples of ansa−spiro substituted fluorinated cyclophosphazenes as well as a bisansa
substituted fluorophosphazene. The bisansa compound {1,3-[FcCH P(S)(CH O)2]}{1,5-[CH (CH O)2]}N P F (4)
2
2
2
2
3 3 2
was found to be nongeminaly substituted with both the ansa rings in cis configuration, which is in stark contrast
to the observations on cyclic chlorophosphazenes where geminal bisansa formation has been observed. The ansa−
spiro compounds (5−7) underwent the ansa to spiro transformation leading to dispiro compounds in the presence
of catalytic amounts of CsF at room temperature. Two of the ansa−spiro compounds, endo-{3,5-[FcCH P(S)-
2
(CH O)2]}{1,1-[CH (CH O)2]}N P F (5) and endo-{3,5-[FcCH P(S)(CH O)2]}{1,1-[FcCH P(S)(CH O)2]}N P F (6),
2
2
2
3
3
2
2
2
2
2
3 3 2
were structurally characterized, and the crystal structures indicate boat−chair conformation as well as crown
conformation for the eight-membered ansa rings. Weak C−H‚‚‚F−P interactions observed in the crystal structures
of the ansa−spiro substituted fluorophosphazene derivatives have been analyzed and compared with C−H‚‚‚F−P
interactions of other fluorinated phosphazenes and thionyl phosphazenes.
Introduction
Among the various products which can result from the
reactions of bifunctional reagents with cyclophosphazenes,
obtaining ansa or transannular substituted cyclophosphazenes
has been quite difficult, since they are found to be thermo-
dynamically less stable compared to the more frequently
observed spiro substituted cyclophosphazenes.5 Recent stud-
ies indicate the requirement of cation assisted supramolecular
effects to prepare ansa substituted chlorophosphazenes while
low-temperature reactions involving dilithiated reagents were
required to prepare ansa substituted fluorophosphazenes.6
Unlike monoansa substituted fluorophosphazenes, there are
no examples of ansa-spiro and bisansa substituted trimeric
fluorophosphazenes known in the literature (Figure 1). It may
be noted that the only known example of a bisansa fluoro-
phosphazene is the nongem “double transannular” bisru-
thenocenyl cyclotetraphosphazene having substitution on
Reactions of difunctional reagents with perhalogenated
cyclophosphazenes have been of considerable interest re-
cently from the perspective of observing regioisomerism in
substitution reactions,1 in synthesizing phosphazene based
macrocycles and air stable inclusion adducts,2,3 as well as
in the preparation of stable trispiro compounds which show
novel shape selective host-guest interaction phenomena.4
* To whom correspondence should be addressed. E-mail: elias@
chemistry.iitd.ac.in.
† Indian Institute of Technology, Kanpur.
‡ Indian Institute of Technology, Delhi.
(1) (a) Allen, C. W. Chem. ReV. 1991, 91, 119-135. (b) Chandrasekhar,
V.; Justin Thomas, K. R. Struct Bonding 1993, 81, 41. (c) Chan-
drasekhar, V.; Krishnan, V. AdV. Inorg. Chem. 2002, 53, 159.
(2) (a) Schneider, R.; Ko¨llner, C.; Weber, I.; Togni, A. Chem. Commun.
1999, 2415-2416. (b) Moriya, K.; Kawanishi, Y.; Yano, S.; Kajiwara,
M. Chem. Commun. 2000, 1111-1112.
(3) (a) Allcock, H. R.; Primrose, A. P.; Silverberg, E. N.; Visscher, K.
B.; Rheingold, A. L.; Guzei, I. A.; Parvez, M. Chem. Mater. 2000,
12, 2530-2536. (b) Allcock, H. R.; Primrose, A. P.; Sunderland, N.
J.; Rheingold, A. L.; Guzei, I. A.; Parvez, M. Chem. Mater. 1999, 11,
1243-1252.
(4) Hertzsch, T.; Budde, F.; Weber, E.; Hulliger, J. Angew. Chem., Int.
Ed. 2002, 41, 2281-2284.
(5) (a) Elias, A. J.; Shreeve, J. M. AdV. Inorg. Chem. 2001, 52, 335-
358. (b) Muralidharan, K.; Reddy, N. D.; Elias, A. J. Inorg. Chem.
2000, 39, 3988-3994.
(6) (a) Brandt, K.; Siwy, M.; Porwolik-Czomperlik, I.; Silbering, J. J. Org.
Chem. 2001, 66, 5701-5712. (b) Muralidharan, K.; Venugopalan, P.;
Elias, A. J. Inorg. Chem. 2003, 42, 3176-3182.
10.1021/ic034712c CCC: $25.00 © 2003 American Chemical Society
Published on Web 10/24/2003
Inorganic Chemistry, Vol. 42, No. 23, 2003 7535

Muralidharan and Elias
separated by column chromatography over silica gel and were
characterized by 31P{1H} and 19F NMR spectral studies and
mass spectral analysis. The structure of compound 5 was
also determined by X-ray crystallography.
Unlike the reactions of chlorophosphazenes, where cation
involved macromolecular assistance was required to prepare
ansa-spiro as well as bisansa substitution on the N3P3 ring,12
this reaction of dilithiated diol at -80 °C afforded a
straightforward method to realize ansa-spiro and bisansa
substitution on the N3P3 ring. For the bisansa compound,
the substitution was found to be nongeminal, which is in
stark contrast to the observations with cyclic chlorophos-
phazenes, where geminal bisansa compounds were found to
be the major or exclusive products. For such a geminal ansa
substitution, the presence of an ansa ring, which also
constituted a macrocycle having a cation, was reported to
be a requirement.12
Figure 1. Possible structural isomers during the secondary stage of
substitution on phosphazene ring by difunctional reagents.
The reaction of the disodium salt of propanediol with 1
was also initially found to yield the bisansa and the ansa-
spiro substituted products 4 and 5, but with passage of time
these compounds transformed to dispiro substituted fluoro-
phosphazenes. A similar reaction of the dilithiated diol,
FcCH2P(S)(CH2OLi)2, with 1 resulted in a complex reaction
mixture, and no pure compounds could be isolated by column
chromatography or by crystallization methods. The complex-
ity of the reaction mixture was possibly due to the presence
of a number of structural isomers, such as the endo-endo,
exo-exo, or endo-exo of the bisansa and the ansa-spiro
substituted products, which are obtainable from the reaction
of this diol with N3P3F6 during multiple stages of substitution.
In contrast, reactions of the dilithiated diols, RCH2P(S)(CH2-
OLi)2 (R ) Fc, C6H5), with the corresponding monospiro
substituted fluorophosphazenes,5b [RCH2P(S)(CH2O)2PN](F2-
PN)2 [R ) Fc (2), C6H5 (3)], at -80 °C resulted in the
formation of novel isomers of ansa-spiro substituted fluo-
rophosphazenes, endo-{3,5-[RCH2P(S)(CH2O)2]}{1,1-[RCH2P-
(S)(CH2O)2]}N3P3F2 [R ) Fc (6), C6H5 (7)] and exo-{3,5-
[RCH2P(S)(CH2O)2]}{1,1-[RCH2P(S)(CH2O)2]}N3P3F2 [R )
Fc (8), C6H5 (9)] (Scheme 2). Compounds 6-9 were
separated by column chromatography over silica gel and
characterized by 31P{1H} and 19F NMR spectral studies and
mass spectral analysis. In addition, compound 6 was also
structurally characterized by X-ray crystallography.
Interestingly, the reactions of the dilithiated diols,
RCH2P(S)(CH2OLi)2 (R) Fc, C6H5), with N3P3F6 at 0 °C,
were found to result in the formation of the ansa-spiro
substituted fluorophosphazenes 6-9, along with the endo
RCH2P(S)(CH2O)2[P(F)N]2(F2PN) (R ) Fc, C6H5) and exo
RCH2P(S)(CH2O)2[P(F)N]2(F2PN) (R ) Fc, C6H5) monoansa
substituted fluorophosphazenes, which we had reported
earlier.5b No bisansa substituted products were isolable from
this reaction mixture. These studies indicate that the forma-
tion of ansa-spiro substituted derivatives is the preferred
pathway at the secondary stage of substitution of trimeric
fluorophosphazenes irrespective of the nature of the precursor
different P atoms of the N4P4 ring.7 The sensitivity of ansa
substituted fluorophosphazenes to undergo ansa to spiro
transformation has also been explored in detail recently.5b,6b,8
To understand the mode of substitution on the fluorophos-
phazene ring during the secondary stage of substitution, we
have performed reactions of bifunctional reagents with
monoansa and monospiro substituted trimeric fluorophos-
phazenes. We report herein the first examples of bisansa and
ansa-spiro substituted fluorinated cyclotriphosphazenes, the
latter being obtained as two different structural isomers.
Involvement of C-H‚‚‚F-C hydrogen bonding as a motif
in supramolecular self-assembly has been of considerable
interest recently.9 While recent reports describe C-H‚‚‚Cl-
P6b,10 and C-H‚‚‚N11 weak interactions involved in substi-
tuted chlorophosphazenes, to the best of our knowledge there
are no reports on the C-H‚‚‚F-P weak interactions in
fluorophosphazenes. In this paper, we report the first detailed
analysis of C-H‚‚‚F-P weak interactions shown by sub-
stituted fluorinated cyclophosphazenes.
Results and Discussion
A reaction of the dilithiated propanediol, LiO(CH2)3OLi,
at -80 °C, with endo-monoansa substituted fluorophos-
phazene FcCH2P(S)(CH2O)2[P(F)N]2(F2PN) (1),5b yielded the
first example of a nongeminal, bisansa substituted trimeric
fluorophosphazene {1,3-[FcCH2P(S)(CH2O)2]}{1,5-[CH2-
(CH2O)2]}N3P3F2 (4) as well as an ansa-spiro substituted
fluorophosphazene {1,1-[CH2(CH2O)2]}{3,5-[FcCH2P(S)-
(CH2O)2]}N3P3F2 (5) (Scheme 1). Compounds 4 and 5 were
(7) Allcock, H. R.; Lavin, K. D.; Riding, G. H.; Whittle, R. R.; Parvez,
M. Organometallics 1986, 5, 1626.
(8) Elias, A. J.; Twamley, B.; Shreeve, J. M. Inorg. Chem. 2001, 40,
2120-2126.
(9) (a) Desiraju, G. R. Acc. Chem. Res. 2002, 35, 565. (b) Thalladi, V.
R.; Weiss, H. C.; Bla¨ser, D.; Boese, R.; Nangia, A.; Desiraju, G. R.
J. Am. Chem. Soc. 1998, 120, 8702-8710. (c) Desiraju, G. R.; Steiner,
T. The weak hydrogen bond; Oxford University Press: Oxford, 1999;
p 20.
(10) Chandrasekhar, V.; Athimoolam, A.; Dastagiri Reddy, N.; Nagendran,
S.; Steiner, A.; Zacchini, S.; Butcher, R. Inorg. Chem. 2003, 42, 51-
59.
(11) Bickley, J. F.; Law, R. B.; Lawson, G. T.; Richards, P. I.; Rivals, F.
Steiner, A.; Zacchini, S. J. Chem. Soc., Dalton Trans. 2003, 1235-
1244.
(12) Brandt, K.; Porwolik-Czomperlik, I.; Siwy, M.; Kupka, T.; Shaw, R.
A.; Davies, D. B.; Hursthouse, M. B.; Sykara, G. A. J. Am. Chem.
Soc. 1997, 119, 12432-12440.
7536 Inorganic Chemistry, Vol. 42, No. 23, 2003

Ansa-Spiro Substituted Fluorophosphazenes
Scheme 1
Scheme 2
being ansa or spiro, and bisansa substitution is less favored
in these reactions.
substitution. This kind of trans-ansa substitution is not
possible with short chain diols such as the ones what we
have chosen for this study, as they are not of sufficient length
to span over the two sides of the phosphazene plane. The
structures b and c can therefore be ruled out. Thus, the only
possible structure for bisansa compound 4 is the nongeminal
cis-bisansa configuration d, which is also in conformity with
the presence of two types of phosphorus and fluorine signals
Characterization of Bis-Ansa Fluorophosphazene (4).
In the 31P{1H} NMR spectrum of the bisansa compound 4,
the peak corresponding to the PdS moiety appeared as a
singlet at 48.61 ppm, which is the typical region for ansa
substituted fluorophosphazenes. The OPF phosphorus was
observed as two different sets of a doublet of multiplets, at
1
for the OPF moiety that are observed in the 31P{1H} and 19
F
24.64 and 21.01 ppm, with JPF coupling constants of 890
and 886 Hz, respectively, indicating the difference in the
two OPF groups that are present in the bisansa compound
4. The same difference was also observed in the 19F NMR
spectrum, in which the fluorines of the OPF groups were
observed as two different sets of doublet of multiplets, which
NMR spectra of this compound. It was of interest to note
that the only other example of a nongem bisansa compound
of chlorophosphazenes reported in the literature belongs to
the nongem cis-trans-ansa configuration b. The trans-ansa
configuration in this case was made possible by the use of
the diol H(OCH2CH2)5OH which formed a large macrocyclic
ring.12
1
appeared at -75.46 and -72.79 ppm, with JPF coupling
constants of 891 and 885 Hz, respectively.
In the 31P{1H} NMR spectrum of the compounds, 5-9,
the peaks corresponding to the PdS moiety appeared in the
range 45.31-49.14 ppm, which was the expected range for
ansa substitution in these compounds. The positions of the
peaks corresponding to the PdS moiety in the spirocyclic
portion of the ansa-spiro compounds 6-9 differ only
slightly from that of the monospiro compound. The fluorine
chemical shifts of the OPF groups in compounds 8 and 9
appeared at -78.90 and -79.33 ppm, respectively, while
that of compound 5 appeared at -71.61 ppm.
The first ansa-spiro substituted chlorophosphazenes was
reported in 1984,13 and the first examples of bisansa
substituted chlorophosphazenes were reported only recently
with geminal bisansa substitution seen as the preferred
substitution route.14 For the bisansa compound prepared in
the present study, one can expect four possible structures as
shown in the Figure 2.
For structure a, the presence of the PF2 group would have
shown a triplet in the 31P NMR spectrum with a 1JPF coupling
constant around 900 Hz. The absence of any such triplets in
the 31P{1H} NMR spectrum and the presence of only doublets
rules out this structure. In the two non gem ansa structures,
b and c, one or both of the diols have formed trans-ansa
(13) Contractor, S. R.; Hursthouse, M. B.; Parkes, H. G.; Shaw, L. S.; Shaw,
R. A.; Yilmaz, H. J. Chem. Soc., Chem. Commun. 1984, 675-676.
(14) (a) Brandt, K.; Porwolik, I.; Olejnik, A.; Shaw, R. A.; Davies, D. B.;
Hursthouse, M. B.; Sykara, G. A. J. Am. Chem. Soc. 1996, 118, 4496-
4497. (b) Brandt, K.; Porwolik, I.; Siwy, M.; Kupka, T.; Shaw, R. A.;
Davies, D. B.; Hursthouse, M. B.; Sykara, G. A. J. Am. Chem. Soc.
1997, 119, 1143-1144.
Figure 2. Possible structural isomers for the bisansa substituted compound
4.
Inorganic Chemistry, Vol. 42, No. 23, 2003 7537

Muralidharan and Elias
conformation was lowest in energy among the 10 possible
conformers.15 The crown conformation is also a stable
conformation but has slightly higher energy compared to that
of the boat-chair conformation. During the reaction with
dianion of the propanediol, the boat-chair conformation of
the monoansa compound 1 has flipped resulting in a crown
conformation in compound 5. One of the possible reasons
for this change of conformation from boat-chair to crown
is that, in compound 5, the N3 nitrogen of the N3P3 ring
flanked between the two ansa forming phosphorus atoms is
at a distance of 0.213(5) Å away from the plane defined by
the rest of the atoms of the phosphazene ring. This nitrogen
was originally deviating at a distance of 0.433(5) Å in the
starting endo-monoansa compound 1.5b This indicates that
changing the conformation of the eight-membered ring from
boat-chair to crown relieves to some extent the strain on
the phosphazene ring. The possibility for the other conforma-
tion to form is not ruled out, as the 31P{1H} spectral analysis
of the reaction mixture indicated the presence of two more
minor compounds with peaks in the region 45.1-48.5 ppm
in very poor yields, which could not be isolated.
Figure 3. ORTEP diagram (50% probability ellipsoids) showing the
molecular structure of the compound 5.
Weak Hydrogen Bonding Interactions in Substituted
Fluorophosphazenes. Unlike the fluoride ion, which forms
significant hydrogen bonds even with C-H groups, the so-
called “organic fluorines” of the C-F group form relatively
very weak and often elusive C-H‚‚‚F-C bonding interac-
tions which often get masked in the presence of hydrogen
bonds involving other elements. Desiraju and co-workers9
as well as others16,17 have recently designed molecules which
elegantly demonstrate weak C-H‚‚‚F-C interactions in
fluorinated aromatic compounds in the absence of other
hydrogen bonding interactions. Although C-H‚‚‚F-P18 and
C-H‚‚‚F-B19 interactions have been observed in ionic
-
-
molecules involving moieties such as PF6 and BF4 , no
systematic study on weak interactions has been performed
on molecules having purely covalent P-F bonds. In many
ways, fluorophosphazenes resemble organofluorine com-
pounds as they are covalent molecules, many of which are
volatile, and the presence of the electronegative fluorines
on these heterocycles reduces drastically the basicity of the
ring nitrogens compared to those of chlorophosphazene
derivatives. Therefore, it was of interest to search for weak
C-H‚‚‚F-P interactions on fluorophosphazene derivatives.
A detailed analysis of the crystal structures of compounds
5 and 6 reveals the existence of interesting C-H‚‚‚F-P weak
hydrogen bonding interactions. This prompted us to study
C-H‚‚‚F-P interactions in other crystal structures of cyclic
fluorophosphazenes, fluorinated thionyl phosphazenes, and
fluorophosphazenate anions as well. Considering the sum
of the van der Waals radii of fluorine and hydrogen atoms
Figure 4. ORTEP diagram (30% probability ellipsoids) showing the
molecular structure of the compound 6.
Structures of Ansa-Spiro Substituted Compounds. The
molecular structures of compounds 5 and 6 are depicted in
Figures 3 and 4, respectively.
In the crystal structure of compound 6, the eight-membered
ring, formed by the ansa substitution, indicates a boat-chair
conformation, which is the conformation normally observed
by almost all eight-membered rings that are formed by ansa
substitution on the N3P3 ring.5b,6b The N3 nitrogen, which is
between the two phosphorus atoms involved in the ansa
substitution, is flanked away from the plane defined by the
other five atoms of the N3P3 ring to a distance of 0.432(5)
Å. This deviation, which indicates a strain on the phos-
phazene ring, was also observed in the endo-monoansa (0.43
Å) and exo-monoansa (0.23 Å) compounds that were
reported earlier.5b In contrast, the eight-membered ansa ring
of compound 5 depicts a crown conformation, which is
unusual when compared with the boar-chair conformation
of known examples of ansa substituted fluorophosphazenes.
Theoretical calculations on the energy of the eight-
membered C-C rings have shown that the boat-chair
(15) Eliel, E. L.; Wilen, S. H.; Mander, L. N. Stereochemistry of organic
compounds; John Wiley: New York, 1994; p 765.
(16) Chandrasekhar, V.; Nagendran, S.; Gopal, K.; Steiner, A.; Zacchani,
S. Chem. Commun. 2003, 862-863.
(17) Lee, H.; Knobler, C. B.; Hawthorne, M. F. Chem. Commun. 2000,
2485-2486.
(18) Grepioni, F.; Cojazzi, G.; Draper, S. M.; Scully, N.; Brago, D.
Organometallics 1998, 17, 296-307.
(19) Brammer, L.; Klooster, W. T.; Lemke, F. R. Organometallics 1996,
15, 1721.
7538 Inorganic Chemistry, Vol. 42, No. 23, 2003

Ansa-Spiro Substituted Fluorophosphazenes
Table 1. C-H‚‚‚F-P Weak Hydrogen Bonding Parameters for
Substituted Fluorinated Phosphazenes, Thionyl Phosphazenes, and
Phosphazenate Anions
interactions are C(5)-H(5) ) 0.93(1) Å, H(5)-F(1) )
2.61(1) Å, C(5)-F(1) ) 3.34(1) Å, C(5)-H(5)-F(1) )
135.3(4)°, and symmetry code ) x, -1 + y, z.] It can be
seen from the figure that one of two nongeminal fluorine
atoms interacts with the hydrogen atom of the cyclopenta-
dienyl ring to form a linear chain of molecules. These chains
are linked further in parallel by H‚‚‚F interactions between
a second fluorine and hydrogen atom in the propanediol
moiety to form a two-dimensional network of the molecules.
In compound 6, the fluorine atoms interact with hydrogen
atoms in the FcCH2 group to form a dimer as shown in Figure
6. [The metric parameters involved in C(16)-H(16B)‚‚‚F(2)
are C(16)-H(16B) ) 0.97(1) Å, H(16B)-F(2) ) 2.58(1)
Å, C(16)-F(2) ) 3.14(1) Å, C(16)-H(16B)-F(2) )
117.0(3)°, and symmetry code is -x, -y, 1 - z.]
C‚‚‚H‚‚‚F
H‚‚‚F
(Å)
C-H‚‚‚F
(deg)
compd
(Å)
ref
5
6
3.34(1)
3.40(1)
3.15(1)
3.14(1)
2.61(1)
2.63(1)
2.58(1)
2.66(6)
135.3(4) this work
136.6(6)
117.0(3) this work
111.3(4) 5b
endo-1,3-[FcCH2P(S)-
(CH2O)2]N3P3F4 (1)
exo-1,3-[FcCH2P(S)-
(CH2O)2]N3P3F4
3.51(1)
3.48(1)
3.30(1)
3.40(1)
3.36(1)
2.58(5)
2.66(5)
2.67(6)
2.60(7)
2.49(6)
146.7(4) 5b
136.7(4)
133.1(5)
151.9(5)
145.6(4) 5b
endo-1,3-[C6H5CH2P(S)-
(CH2O)2]N3P3F4
1,1-[OCH2(CF2)2-
CH2O]N4P4F6
1,1-[S(CH2)2O]N3P3F4
1,1-[S(CH2)3O]N3P3F4
1,1-[S(CH2)2S]N3P3F4
1,1-[S(CH2)3S]N3P3F4
3.41(1)
3.02(1)
3.31(2)
3.35(1)
3.36(1)
3.65(1)
3.52(1)
3.19(1)
3.49(6)
3.40(1)
3.27(1)
3.28(2)
3.47(1)
3.51(5)
3.41(1)
3.49(1)
3.39(2)
3.55(1)
3.31(1)
3.48(1)
3.30(1)
3.24(1)
3.46(2)
3.16(1)
3.61(1)
2.58(1)
2.56(1)
2.57(3)
2.69(5)
2.70(4)
140.4(2)
108.1(2)
128.5(2) 21
127.8(4) 21
125.0(3) 21
8
Transformations of Ansa-Spiro Substituted Com-
pounds to Dispiro Substituted Compounds. The ansa-
spiro substituted compounds 6 and 8 were treated separately
with catalytic amounts of CsF in THF, and the course of the
reaction was monitored by time-dependent 31P{1H} NMR
spectroscopy. After the entire amount of compound 6 or 8
disappeared, the analysis of the reaction mixture by 31P{1H},
2.60(12) 161.9(9) 21
2.64(12) 138.4(9)
N3P3F4[1,2-C6H4O2]
N3P3F4[1,2-C6H4O2]2
N3P3F4[2,3-C10H6O2]
N3P3F4[2,2′-C12H8O2]
2.61(3)
2.68(5)
2.61(1)
2.60(6)
2.44(2)
2.59(1)
2.64(4)
2.51(1)
2.57(1)
2.69(1)
2.65(3)
2.44(2)
2.70(3)
2.48(4)
2.58(4)
2.59(3)
2.49(1)
2.65(1)
119.0(1) 21
148.9(4) 21
138.3(3) 21
129.0(5) 21
142.7(8) 22
149.6(5)
147.5(7)
153.5(4)
157.4(5)
128.1(6)
152.0(1) 22
147.5(1)
137.4(2)
140.5(3)
125.6(3)
147.7(2)
128.2(4) 23
173.8(5)
-a
N4P4F9
1
19F, and H NMR spectra indicated the formation of three
isomers of dispiro compounds. Extremely close mobility for
the three compounds precluded separation of these com-
pounds by column chromatography over silica gel or
alumina. An attempted sublimation also failed to separate
this mixture. However, one of the compounds crystallized
out from the solution of a mixture in ethyl acetate/hexane.
This compound was characterized as dispiro-{1,1,3,3-
[FcCH2P(S)(CH2O)2]2}N3P3F2 (10) by NMR and mass
spectral studies.
-a
N6P6F13
NSO(4-tBuC6H4)[NPF2]2
a The C-H bonds belong to the NMe2 groups of the cation (Me2N)3S+.
As desilylation reactions of silylated diols exclusively give
spirocyclic compounds, we reacted 2 mol of the disilylated
diol, FcCH2P(S)(CH2OSiMe3)2, with 1 mol of N3P3F6 in the
presence of catalytic amount of CsF in THF. The spectral
data obtained for this reaction mixture were compared with
that of the mixture obtained from the transformation study
and found that this reaction also yielded the same mixture
of three dispiro compounds. Analysis of the crystal structures
of spirocyclic compounds resulting from the reactions of the
phosphine sulfide diol RCH2P(S)(CH2OH)2 (R ) Fc, C6H5)
indicates that, as part of a rigid six-membered chair
conformation, the S atom of the PdS group always occupies
the equatorial position.5b,6b This observation was also ap-
plicable to the spiro substituted compounds of carbaphos-
phazene24 and thionylphosphazene25 as well. Considering this
factor, one can propose possible isomeric structures for the
three dispiro compounds as given in Figure 7. However
as per Bondi,20 we restricted the maximum distance between
the H and F atoms to 2.70 Å and studied the C-H‚‚‚F-P
hydrogen bonding interactions.9c The C-H‚‚‚F-P hydrogen
bonding parameters of substituted fluorinated phosphazenes,
thionyl phosphazenes, and phosphazenate anions are listed
in Table 1.
As expected, the C-H‚‚‚F-P interactions for the phos-
-
-
phazenate anions N4P4F9 and N6P6F13 were found to be
the strongest as indicated by an H‚‚‚F distance of 2.44(2)
Å. Among the neutral compounds, the thionylphosphazene
NSO(4-tBuC6H4)[NPF2]2 [2.49(1) Å] and the substituted
fluorophosphazene endo-1,3-[C6H5CH2P(S)(CH2O)2]N3P3F4
[2.49(6) Å] showed relatively significant interactions. The
ansa-spiro compounds 5 and 6 showed C-H‚‚‚F-P inter-
actions in the range 2.58-2.62 Å which is well with in the
accepted range of C-H‚‚‚F interactions. The two-dimen-
sional structure developed by C-H‚‚‚F-P interactions in
compound 5 is shown in Figure 5. [The metric parameters
involved in C(15)-H(15B)‚‚‚F(2) interactions are C(15)-
H(15B) ) 0.97(1) Å, H(15B)-F(2) ) 2.63(1) Å, C(15)-
F(2) ) 3.40(1) Å, C(15)-H(15B)-F(2) ) 136.6(6)°, and
symmetry code ) 1 + x, y, z. In C(5)-H(5)‚‚‚F(1),
(21) Vij, A.; Geib, S. J.; Kirchmeier, R. L.; Shreeve, J. M. Inorg. Chem.
1996, 35, 2915-2929.
(22) Lork, E.; Bo¨hler, D.; Mews, R. Angew. Chem., Int. Ed. Engl. 1995,
34, 2696-2698.
(23) Elias, A. J.; Twamley, B.; Shreeve, J. M. Inorg. Chem. 2001, 40,
2120-2126.
(24) Reddy, N. D.; Elias, A. J.; Vij, A. Inorg. Chem. Commun. 2000, 3,
29-31.
(25) (a) Ramakrishna, T. V. V.; Elias, A. J. J. Organomet. Chem. 2001,
637-639, 382-389. (b) Ramakrishna, T. V. V.; Elias, A. J.; Vij, A.
J. Organomet. Chem. 2000, 602, 125-132.
(20) Bondi, A. J. Phys. Chem. 1964, 68, 441.
Inorganic Chemistry, Vol. 42, No. 23, 2003 7539

Muralidharan and Elias
Figure 5. Two-dimensional network of the molecules developed by C-H‚‚‚F-P interactions in the crystal structure of the ansa-spiro compound 5 (viewed
through c axis).
An attempted transformation study of the bisansa compound
4 was inconclusive as the study led to a complex mixture of
products.
We have also attempted ansa to spiro transformation of
the ansa-spiro substituted compound 5 in the presence of
CsF in THF and monitored the reaction by 31P{1H} NMR
spectroscopy. As expected, there was only one peak corre-
sponding to the PdS moiety in the spiro region at 20.11
ppm in the 31P{1H} NMR spectrum. A triplet of multiplets
corresponding to the PF2 group also started appearing after
16 h at 7.76 ppm with a coupling constant of 906 Hz.
Purification of this reaction mixture by column chromatog-
raphy yielded the dispiro compound {1,1-[FcCH2P(S)-
(CH2O)2]}{3,3-[OCH2CH2CH2O]}N3P3F2 (11) (Scheme 3).
The transformation of ansa-spiro compound 5 to dispiro
compound 11 was relatively slower with only partial
Figure 6. Dimer formed by the C-H‚‚‚F-P interactions in the crystal
structure of the ansa-spiro compound 6.
transformation observed even after 11 days of stirring at room
temperature.
Conclusions
assignment of the spectral data to each isomeric structure
separately proved quite difficult.
In conclusion, we have carried out the first systematic
study on the reactions of monoansa and monospiro substi-
tuted fluorophosphazenes with difunctional reagents. The
study indicates that the formation of ansa-spiro substituted
derivatives is the preferred pathway at the secondary stage
of substitution of trimeric fluorophosphazenes irrespective
of the nature of the precursor being ansa or spiro. The study
has resulted in the synthesis of five novel examples of ansa-
The transformations of ansa-spiro substituted compounds
to the dispiro isomers were slower than transformation of
monoansa compounds to their spiro isomers. Time-dependent
NMR studies indicate that, to complete the transformation
from ansa-spiro to dispiro isomers, compounds 6 and 8 take
14 h, while the corresponding monoansa compounds take
only 3-4 h for complete transformation to their spiro isomer.
7540 Inorganic Chemistry, Vol. 42, No. 23, 2003

Ansa-Spiro Substituted Fluorophosphazenes
Figure 7. Possible structural isomers of the dispiro compound -{1,1,3,3-[FcCH2P(S)(CH2O)2]2}N3P3F2.
Scheme 3
recorded as KBr pellets on a Bruker vector 22 FTIR spectrometer
operating at 400-4000 cm-1
.
X-ray Diffraction Studies. The X-ray diffraction data for
compounds 5 and 6 were collected on an Enraf-Nonius CAD-4
diffractometer. The structure was solved by using WINGX version
1.64.04, a crystallographic collective package.28 The structures were
solved initially by SIR-9729 and refined with SHELX-9730 which
are incorporated in the WINGX program. The structures were
refined against F2 with a full-matrix least-squares algorithm. All
non-hydrogen atoms were refined anisotropically, and the hydrogen
atoms were generated by HFIX command and refined isotropically.
The X-ray data pertaining to data collection, crystal systems, and
structure solution as well the selected bond distances and angles
for the compounds 5 and 6 are given in the Supporting Information.
spiro substituted fluorophosphazenes and nogem cis-bisansa
substituted fluorophosphazenes, which are all the first
examples of their kind. All the ansa-spiro compounds were
found to transform to their dispiro isomer in the presence of
CsF as catalyst, which further confirms the higher thermo-
dynamic stability of spirocylic isomers over the ansa
analogues. The crystal structures of the ansa-spiro com-
pounds show typical boat-chair conformations as well as
rare crown conformations for eight-membered ansa rings.
The C-H‚‚‚F-P weak interactions observed in the ansa-
spiro substituted fluorophosphazenes were determined and
compared with similar weak C-H‚‚‚F-P interactions in
substituted fluorinated phosphazenes, thionylphosphazenes,
and fluorophosphazenate anions. The C-H‚‚‚F-P distances
were found as low as 2.44(2) Å for phosphazenate anions
Reaction of 1 with 1,3-Propanediol. The diol CH2(CH2OH)2
(0.11 g, 1.5 mmol) was treated with n-BuLi (1.87 mL, 3.0 mmol)
in dry THF (10 mL) at -80 °C, and the mixture was stirred for 4
h before the endo-monoansa compound FcCH2P(S)(CH2O)2[P(F)N]2-
(F2PN) (0.80 g, 1.5 mmol) dissolved in dry THF (20 mL) was added
at -80 °C under nitrogen atmosphere. After 12 h of stirring at room
temperature, the solvent was removed under vacuum, the residue
dissolved in minimum amount of dichloromethane and the LiF
formed filtered off using a frit. After analysis by TLC, the reaction
mixture was separated by column chromatography, and two
products were isolated. The first compound which came out of the
column was identified as the ansa-spiro compound, {1,1-[CH2-
(CH2O)2]}{3,5-[FcCH2P(S)(CH2O)2]}N3P3F2 (5). Yield: 0.26 g,
30.4%. Mp: 141 °C. IR (KBr) (cm-1): 2924 s, 1467 w, 1413 w,
1254 vs, 1142 w, 1042 vs, 968 s, 919 w, 879 s, 841 s, 809 w, 761
s, 460 vs. NMR: 1H, δ 4.44-4.63 (m, 8H, CH2O), 4.31-4.34 [m,
2H, (ηC5H4)], 4.12-4.14 [m, 2H, (ηC5H4)], 4.11 [s, 5H, (ηC5H5)],
3.15 [d (J ) 11 Hz), 2H, FcCH2P], 2.02 [quintet, 2H, CH2CH2-
CH2)]; 31P{1H}, δ 48.61 (s, PdS ansa) 13.19 [dd (2JPNP ) 106.7
Hz), OPO], 16.09 [md (1JPF)916.0 Hz), OPF]; 19F, δ -71.61 [md
(1JPF ) 931.2 Hz), OPF]; 13C{1H}, δ 25.96 (s, CH2CH2CH2), 28.07
(FcCH2), 66.68 [d (J ) 45 Hz), CH2O], 67.93 [d (J ) 42 Hz),
CH2O], 68.89 [s, C(5) and C(8)], 69.07 [s, C(9)-C(13)], 70.01 [s,
C(6)-C(7)]. MS (FAB) [m/e (species) intensity]: 569 (M+) 100,
307 [FcCH2P(S)(CH2O)(CH2)-H+] 18, 199 (FcCH2) 36, 154
(N3P3F1) 78, 135 (N3P3) 68. Anal. Calcd for C16H21O4P4N3F2S1Fe
(%): C, 33.76; H, 3.72; N, 7.38. Found: C, 33.58; H, 3.54; N,
7.52.
-
-
N4P4F9 and N6P6F13 and 2.49(6) Å for ansa substituted
fluorophosphazene 1,3-[C6H5CH2P(S)(CH2O)2]N3P3F4.
Experimental Section
General Procedures. A conventional vacuum line equipped with
a dry nitrogen apparatus and Schlenk glassware was used for all
reactions. Reactions and workup procedures were carried out under
an atmosphere of dry nitrogen. N3P3F6 was prepared from N3P3Cl6
(Fluka) according to the literature method26 and was purified by
fractional distillation (caution: N3P3F6 is a potentially toxic
compound and has high vapor pressure at room temperature). The
synthesis of the diol, RCH2P(S)(CH2OH)2 (R ) Fc, C6H5),
disilylated diol FcCH2P(S)(CH2OSiMe3)2, the monoansa compound
endo-{FcCH2P(S)(CH2O)2[P(F)N]2(F2PN)}, and the monospiro
compound RCH2P(S)(CH2O)2PN](F2PN)2 (R ) Fc, C6H5) were
carried out as given in the literature.5b,27 1,3-Propanediol was used
as obtained from Lancaster. Hexane, ethyl acetate, dichloromethane,
and tetrahydrofuran were distilled and dried by standard procedures.
The second compound was identified as the bisansaphospha-
zene {1,3-[FcCH2P(S)(CH2O)2]}{1,5-[CH2(CH2O)2]}N3P3F2 (4).
Yield: 0.19 g, 22.2%. Mp: 138 °C. IR (KBr)(cm-1): 2920 w, 1460
s, 1264 vs, 1147 w, 1051 vs, 962 w, 875 s, 851 s, 822 s, 761 s, 465
1
Instrumentation. H, 31P{1H}, 19F, and 13C{1H} NMR spectra
were recorded using a JEOL JNM-LA 400 FT NMR spectrometer
with CDCl3, as solvent. The chemical shifts are reported with
1
respect to the internal standards, TMS (for H), 85% H3PO4 [for
(28) Farrugia, L. J. WinGXsA windows program for crystal structure
analysis; University of Glasgow: Glasgow, 1998. Farrugia, L. J. J.
Appl. Crystallogr. 1999, 32, 837-838.
31P{1H}], and CFCl3 (for 19F). Mass spectra were obtained on a
JEOL D-300 spectrometer. Elemental analyses were carried out
Carlo-Erba CHNO 1108 elemental analyzer. IR spectra were
(29) Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G. L.; Giaco-
vazzo, C.; Guagliardi, A.; Moliterni, A. G. G.; Polidori, G.; Spagna,
R. J. Appl. Crystallogr. 1999, 32, 115-119.
(26) Schmutzler, R. Inorg. Synth. 1967, 9, 75.
(27) Goodwin, N. J.; Henderson, W.; Nicholson, B. K.; Sarfo, J. K.;
Fawcett, J.; Russell, D. R. J. Chem. Soc., Dalton Trans. 1997, 4377.
(30) Sheldrick, G. M. SHELX97, Programs for Crystal Structure Analysis
(Release 97-2); Institu¨t fu¨r Anorganische Chemie der Universita¨t:
Go¨ttingen, Germany, 1998.
Inorganic Chemistry, Vol. 42, No. 23, 2003 7541

Muralidharan and Elias
s. NMR: 1H, δ 4.77-4.67 and 4.52-4.34 (two set of multiplets,
8H, CH2O), 4.26-4.29 [m, 2H, (ηC5H4)], 4.12-4.16 [m, 2H,
(ηC5H4)], 4.09 [s, (ηC5H5)], 3.40 to 3.17 (m, 2H, FcCH2P), 2.24-
2.02 (m, CH2CH2CH2); 31P{1H}, δ 46.10 (s, PdS ansa), 18.46 [dd
(2JPNP ) 94.1 Hz), OPO], 24.64 [md (1JPF ) 891.0 Hz), OPF] 21.01
[md (1JPF ) 886.1 Hz), OPF]; 19F, δ -75.46 [md (1JPF ) 891.1
Hz), OPF], -72.79 [md (1JPF ) 885.5 Hz), OPF];13C{1H}, δ 30.01
(s, CH2CH2CH2), 29.15 (s, FcCH2), 67.91 [d (J ) 45 Hz), CH2O],
68.87 [d (J ) 42 Hz), CH2O], 69.12 [s, â-C], 69.37 [s, η-C5H5],
71.01 [s, γ-C]. MS (FAB) [m/e (species) intensity]: 569 (M+) 100,
307 [FcCH2P(S)(CH2O)(CH2)-H+] 18, 199 (FcCH2) 16, 154
(N3P3F1) 40, 135 (N3P3) 26. Anal. Calcd for C16H21O4P4N3F2S1Fe
(%): C, 33.76; H, 3.72; N, 7.38. Found: C, 33.66; H, 3.47; N,
7.42.
at -80 °C under nitrogen atmosphere. The reaction was worked
up as described for compounds 4 and 5. The compound which came
out first from the column was identified as endo-{3,5-[C6H5CH2P-
(S)(CH2O)2]}{1,1-[C6H5CH2P(S)(CH2O)2]}N3P3F2 (7). Yield: 0.026
g, 30.7%. Mp: 108 °C. IR (KBr)(cm-1): 2924 s, 1492 w, 1453 w,
1413 s, 1261 vs, 1178 w, 1049 vs, 978 vs, 930 w, 901 s, 871 vs,
773 vs, 735 w, 699 s, 628 s, 571 w, 527 w, 508 vs, 459 w. NMR:
1H, δ 7.34-7.28 (m, 10H, C6H5), 4.88-4.80 and 4.52-4.28 (two
set of multiplets, 8H, CH2O), 3.71 [d (J ) 14 Hz), 2H, C6H5CH2,
(ansa)], 3.64-3.61 [m, 2H, C6H5CH2 (spiro)]; 31P{1H}, δ 47.45
(s, PdS ansa), 22.32 [d (3JPF ) 14.55 Hz), PdS spiro], 16.75-
15.25 (m, OPO), 15.90 [md (1JPF ) 939.5 Hz), OPF]; 19F, δ -74.90
[md (1JPF ) 938.1) OPF], -74.47 [md (1JPF ) 934.9), OPF]. MS
(FAB) [m/e (species) intensity]: 601 (M+) 90, 404 [C6H5CH2P-
(S)(CH2O)2P3N3OH] 100, 154 (N3P3F1) 62, 135 (N3P3) 72. Anal.
Calcd for C18H22P5N3O4F2S2 (%): C, 35.95; H, 3.69; N, 6.99.
Found: C, 35.90; H, 3.60, N, 6.81.
Reaction of Compound 2 with FcCH2P(S)(CH2OLi)2. The diol
FcCH2P(S)(CH2OH)2 was treated with n-BuLi (0.37 mL, 6.0 mmol)
in dry THF (10 mL) at -80 °C, and the mixture was stirred for 4
h before the spiro compound FcCH2P(S)(CH2O)2PN](F2PN)2 (0.16
g, 3.0 mmol) dissolved in dry THF (10 mL) was added at -80 °C
under nitrogen atmosphere. The reaction was worked up as
described for compounds 4 and 5. The first compound which came
out of the column was identified as endo-{3,5-[FcCH2P(S)-
(CH2O)2]}{1,1-[FcCH2P(S)(CH2O)2]}N3P3F2 (6). Yield: 0.09 g,
36.8%. Mp: 166 °C. IR (KBr)(cm-1): 3430 w, 3143 w, 3082 s,
1738 s, 1639 w, 1463 s, 1411 vs, 1263 vs, 1219 s, 1165 s, 1035
vs, 971 w, 938 s, 891 s, 872 vs, 826 s, 771 vs, 716 w, 641 s, 590
w, 533 s, 480 vs. NMR: 1H, δ 4.91-4.40 (m, 8H, CH2O), 4.30-
4.15 [m, 8H, (ηC5H4)], 4.12 [s, 5H, (ηC5H5)], 4.06 [s, 5H, (ηC5H5)],
3.44-3.40 [m, 2H, FcCH2P (spiro)], 3.14 [d (J ) 11 Hz), 2H,
The second compound was identified as exo-{3,5-[C6H5CH2P-
(S)(CH2O)2]}{1,1-[C6H5CH2P(S)(CH2O)2]}N3P3F2 (9). Yield: 0.023
g, 27.1%. Mp: 135 °C. IR (KBr)(cm-1): 2920 w, 1463 w, 1415 s,
1265 vs, 1168 w, 1052 vs, 970 vs, 901 s, 773 s, 735 w, 690 s, 638
s, 576 w, 527 w, 508 vs. NMR: 1H, δ 7.34-7.29 (m, 10H, C6H5),
4.86-4.78 and 4.58-4.34 (two set of multiplets, 8H, CH2O), 3.69-
3.67 [m, 2H, C6H5CH2 (spiro)], 3.53 [d (J ) 14 Hz), 2H, C6H5CH2,
(ansa)]; 31P{1H}, δ 49.14 (s, PdS ansa), 22.41 [d (3JPF ) 14.55
Hz), PdS spiro], 18.46 [md (2JPNP ) 101.9), OPO], 14.89 [md (1JPF
) 854.6 Hz), OPF]; 19F, δ -79.33 [md (1JPF ) 879.0 Hz), OPF].
MS (FAB) [m/e (species) intensity]: 601 (M+) 100, 404 [PhCH2P-
(S)(CH2O)2P3N3OH] 15, 154 (N3P3F) 91, 135 (N3P3) 61.
FcCH2P (ansa)]; 31P{1H}, δ 45.31 (s, PdS ansa), 20.23 [d (3JPP
16.17 Hz), PdS spiro] 14.72-16.95 (m, OPO), 15.55 [md (1JPF
)
)
Reaction of FcCH2P(S)(CH2OLi)2 with N3P3F6 at 0 °C. The
compound FcCH2P(S)(CH2OH)2 (0.62 g, 1.9 mmol) was treated
with n-BuLi (2.40 mL, 3.84 mmol) in dry THF (30 mL) at -80
°C, and the mixture was stirred for 4 h before N3P3F6 (0.48 g, 1.9
mmol) dissolved in dry THF (30 mL) was added at 0 °C under a
nitrogen atmosphere. The mixture was brought to room temperature,
and after 12 h of stirring, the solvent was removed under vacuum,
the residue was dissolved in minimum amount of dichloromethane,
and the LiF that formed was filtered off using a frit. The reaction
mixture was analyzed by TLC. Upon separation by column
chromatography using ethyl acetate/hexane over silica gel, three
products were isolated. The first two fractions were identified as
endo-monoansa FcCH2P(S)(CH2O)2[P(F)N]2(F2PN) (1) (0.31 g,
30%) and exo-monoansa FcCH2P(S)(CH2O)2[P(F)N]2(F2PN) (0.12
g, 11.7%), respectively. The spectral data of these compounds were
compared to those of the authentic sample.5b The analysis of the
31P{1H} NMR spectrum of the third fraction showed it as mixture
(0.23 g) of endo ansa-spiro 6 and exo ansa-spiro 8. Separation
of this mixture again by column chromatography yielded compound
6 (0.11 g) and compound 8 (0.09 g). The spectral data of these
compounds were compared to those of the compounds obtained in
the reaction of the monospiro-[FcCH2P(S)(CH2O)2PN](F2PN)2 with
the corresponding dilithiated diol.
911.2 Hz), OPF]; 19F, δ -74.60 [md (1JPF ) 937.0 Hz), OPF],
-73.99 [md (1JPF ) 937.9 Hz), OPF]; 13C{1H}, δ 73.40 (s, R-C of
ηC5H4, spiro), 74.20 (s, R-C of ηC5H4, ansa), 69.71, 69.55, 68.98,
68.79 (all singlets, â and γ C of ηC5H4), 69.15 (s, ηC5H5), 66.82
[d (J ) 41 Hz), PCH2O ansa], 66.54 [d (J ) 41 Hz), PCH2O spiro],
28.21 [d (J ) 42 Hz), FcCH2P ansa], 28.80 [d (J ) 43 Hz), FcCH2P
ansa]. MS (FAB) [m/e (species) intensity]: 817 (M+) 32, 307
[FcCH2P(S)(CH2O)(CH2)-H+] 100, 199 (FcCH2) 58. Anal. Calcd
for C26H30O4P5N3F2S2Fe2 (%): C, 38.21; H, 3.70; N, 5.14. Found:
C, 38.16, H, 3.57, N, 5.30.
The second compound obtained was identified as exo-
{3,5-[FcCH2P(S)(CH2O)2]}{1,1-[FcCH2P(S)(CH2O)2]}N3P3F2 (8).
Yield: 0.06 g, 24.6%. Mp: 129 °C. IR (KBr)(cm-1): 2852 s, 2738
w, 1414 w, 1248 vs, 1042 s, 979 vs, 872 s, 808 s, 773 s, 725 vs,
642 w, 501 vs. NMR: 1H, δ 4.84-4.77 and 4.48-4.35 (two set of
multiplets, 8H, CH2O), 43.31-4.18 [m, 8H, (ηC5H4)], 4.16 [s, 5H,
(ηC5H5)], 4.15 [s, 5H, (ηC5H5)], 3.50 [d (J ) 12 Hz), 2H, FcCH2O
(ansa)], 3.45-3.42 [m, 2H, FcCH2O (spiro)]; 31P{1H}, δ 47.45 (s,
PdS ansa), 22.32 [d (3JPP ) 14.5 Hz), PdS spiro], 18.84-17.93
(m, OPO), 15.90 [md (1JPF ) 939.5 Hz), OPF]; 19F{31P}, δ -78.90
[md (1JPF ) 878 Hz), OPF]; 13C{1H}, δ 75.07 (s, R-C of ηC5H4,
spiro), 74.29 (s, R-C of ηC5H4 ansa), 69.76, 69.51, 68.91, 68.70
(all singlets, ηC5H4), 69.06 (s, ηC5H5), 67.07 [d, (J ) 41 Hz),
PCH2O ansa], 66.24 [d, (J ) 41 Hz), PCH2O spiro], 29.54 [d (J )
42 Hz), FcCH2P ansa], 28.88 [d (J ) 43 Hz), FcCH2P ansa]. MS
(FAB) [m/e (species) intensity]: 817 (M+) 100, 307 [FcCH2P(S)-
(CH2O)(CH2)-H+] 31, 199 (FcCH2) 22.
Reaction of C6H5CH2P(S)(CH2OLi)2 with N3P3F6 at 0 °C. The
compound C6H5CH2P(S)(CH2OH)2 (0.17 g, 0.8 mmol) was treated
with n-BuLi (1 mL, 1.6 mmol) in dry THF (30 mL) at -80 °C,
and the mixture was stirred for 4 h before N3P3F6 (0.20 g, 0.8 mmol)
dissolved in dry THF (30 mL) was added at 0 °C under a nitrogen
atmosphere. After 12 h of stirring at room temperature, the residue
was worked up as described for the previous reaction. After
separation by column chromatography, the first two fractions were
identified as endo-monoansa C6H5CH2P(S)(CH2O)2[P(F)N]2(F2PN)
(0.05 g, 14.6%) and exo-monoansa C6H5CH2P(S)(CH2O)2[P(F)N]2-
(F2PN) (0.01 g, 2.9%), respectively. The spectral data of these
Reaction of Compound 3 with C6H5CH2P(S)(CH2OLi)2. The
diol C6H5CH2P(S)(CH2OH)2 was treated with n-BuLi (0.17 mL,
2.8 mmol) in dry THF (10 mL) at -80 °C, and the mixture was
stirred for 4 h before the compound C6H5CH2P(S)(CH2O)2PN](F2-
PN)2 (0.06 g, 1.4 mmol) dissolved in dry THF (10 mL) was added
7542 Inorganic Chemistry, Vol. 42, No. 23, 2003

Ansa-Spiro Substituted Fluorophosphazenes
compounds were compared to those of authentic samples.5b The
analysis of 31P{1H} NMR spectrum of third fraction showed it as
mixture (0.06 g) of endo ansa-spiro (7) and exo ansa-spiro (9).
Separation of this mixture again by column chromatography yielded
compound 7 (0.027 g) and compound 9 (0.029 g). The spectral
data of these compounds were found to agree with those of
authentic samples.5b
General Procedure for the Transformation of Ansa-Spiro
Substituted Compounds into Dispiro Compounds. The ansa-
spiro compounds were dissolved separately in THF, and catalytic
amounts of CsF (5-10 mol %) were added to them. The mixtures
were stirred at room temperature, and the reaction was monitored
by 31P{1H} NMR spectra till the peaks corresponding to the PdS
in the ansa region disappeared. Afterward, the THF was evaporated,
and the mixture was dissolved in ethyl acetate and passed through
a column packed with silica gel to filter off the CsF and insoluble
materials. The filtrate was further purified by column chromatog-
raphy and by crystallization to get dispiro compounds.
δ -68.29 [td, (J ) 920 Hz); and 31P{1H}, δ 22.28 [d, PdS, (J )
18 Hz)], a multiplet merged with triplet of PF2 for OPO, 9.01 [mt,
PF2, (J ) 906 Hz)]; 19F, δ -68.17 [td, PF2, (J ) 935 Hz)].
Dispiro {1,1-[FcCH2P(S)(CH2O)2]}{3,3-[OCH2CH2CH2O]}-
N3P3F2 (11). Mp: charring at 160 °C. NMR: 1H, δ 4.73-4.30 (m,
8H, CH2O), 4.26-4.06 (m, 9H, Fc), 3.34 [d (J ) 12 Hz), FcCH2P],
1.90 (quintet, 2H, CH2CH2CH2); 31P{1H}, δ 22.11 [d (3JPP ) 15
Hz), PdS], 15.88 [mt (2JPNP ) 101 Hz), OPO], 12.88 (m, OPO),
7.76 [mt (1JPF ) 906 Hz), PF2]; 19F, δ -68.12 [md (1JPF ) 902
Hz), PF2]; 13C{1H}, δ 75.33 (s, R-C of ηC5H4), 69.61 and 68.78
(s, ηC5H4), 69.04 (s, ηC5H5), 67.62 (s, CH2O), 66.09 [d (J ) 53
Hz), PCH2O], 29.91 [d (J ) 71 Hz), FcCH2P], 25.74 (s, CH2CH2-
CH2). MS(FAB) [m/e (species) intensity]: 567 (M+) 100, 307
(FcCH2P(S)(CH2O)(CH2)-H+ 20, 199 (FcCH2) 20, 135 (N3P3) 38.
Anal. Calcd for C16H21O4P4N3F2S1Fe (%): C, 33.76; H, 3.72; N,
7.38. Found: C, 33.60; H, 3.52; N, 7.20.
Acknowledgment. A.J.E. thanks CSIR India, DST, India,
and IRD, IIT Delhi, for financial assistance in the form of
research grants. K.M. is thankful to CSIR India for a senior
research fellowship. We thank CDRI Lucknow for mass
spectral data.
Spectral Data for Dispiro Compounds. Dispiro 1,1,3,3-
[FcCH2P(S)(CH2O)2]2N3P3F2 (10). Mp: 121 °C. NMR: 1H, δ
4.80-4.77 and 4.41-4.32 (two set of multiplets, 8H, CH2O), 4.28-
4.14 [two set of multiplets, 8H, (ηC5H4)], 4.11 [s, (ηC5H4)], 3.40
[d (J ) 11 Hz), 4H, FcCH2P]; 31P{1H}, δ 19.6 [d (JPP ) 10 Hz),
PdS], 16.20 [dd (JPNP ) 90 Hz, 14 Hz), OPO], 5.86 [tt (2JPNP
)
Supporting Information Available: Crystallographic informa-
tion file (CIF) as well as X-ray data pertaining to data collection,
crystal systems, and structure solution. Selected bond distances and
angles and conformations of eight-membered ansa rings of com-
pounds 5 and 6. This material is available free of charge via the
Internet at http://pubs.acs.org.
96 H, JPF ) 913 Hz), PF2]; 19F, δ -68.35 [td (JPF ) 913 and 14
Hz), PF2]. MS (FAB) [m/e (species) intensity]: 817 (M+) 90, 307
[FcCH2P(S)(CH2O)(CH2)-H+] 60, 199 (FcCH2) 100. Anal. Calcd
for C26H30O4P5N3F2S2Fe2 (%): C, 38.21; H, 3.70; N, 5.14. Found:
C, 38.32, H, 3.85, N, 5.06. 31P{1H} and 19F NMR spectral data for
other two isomers are as follows.31P{1H} 20.87 [d, PdS (J ) 16
Hz)], 17.20-15.90 (m, OPO), 8.36 [mt, PF2, (J ) 906 Hz)]; 19F,
1
IC034712C
Inorganic Chemistry, Vol. 42, No. 23, 2003 7543