Synthesis and reactions of ethynylferrocene-derived fluoro- and chlorocyclotriphosphazenes

Article abstract of DOI:10.1021/ic100703h

The reactions of lithiated ethynylferrocene, FcC≡CLi (Fc = ferrocenyl), with fluoro- and chlorocyclotriphosphazenes, N₃P ₃X₆ (X = F, Cl), resulted in the formation of stable mono-FcC≡CP₃N₃X₅ [X = F (1), Cl (2)] and geminal bis[(FcC≡C)₂PN](X₂PN)₂ [X = F (3), Cl (4)], ethynylferrocene-substituted cyclophosphazenes. The reactions of 1 and 2 with CpCo(COD) were found to differ in the nature of the sandwich compounds (η⁵-Cp)Co{η⁴-C₄[Fc ₂(N₃P₃X₅)₂]} formed. While the fluorophosphazene-derived compound 1 yielded both cis and trans isomers of the cyclobutadiene complexes 5 and 6, the chlorophosphazene-derived compound 2 was found to give only the trans-cyclophosphazene-disubstituted cyclobutadiene compound 7. The reaction of 3 with CpCo(COD) was found to give the compound (η⁵-Cp)Co{η⁴-C₄-1,3-(Fc) ₂-2,4-[NP(C≡CFc)(NPF₂)₂]₂} (8) having one of the alkyne units of the cyclophosphazene moiety of 3 remaining unreacted even after reaction with an excess of CpCo(COD). The first click reactions of ethynylferrocene-derived cyclophosphazenes have been carried out by reacting 1 and 4 with benzyl azide, resulting in novel mono- and disubstituted cyclophosphazene-derived 1,2,3-triazoles. The reaction of 1 with benzyl azide yielded two positional isomers of the 1,2,3-triazole, (1-PhCH₂, 4-Fc, 5-P₃N₃F₅)C₂N₃ (9), and (1-PhCH₂, 4-P₃N₃F₅, 5-Fc)C ₂N₃ (10), with the latter having a benzyl group in the vicinity of the ferrocene unit as the major product. A similar reaction of 4 with benzyl azide was found to yield five triazole-based products, with two, [(1-PhCH₂-4-FcC₂N₃)(C≡CFc)PN](PNCl ₂)₂ (11) and [(1-PhCH₂-5-Fc-C₂N ₃)(C≡CFc)PN](PNCl₂)₂ (12), having one unreacted alkyne unit in the molecule. Among the bis-triazole-derived chlorophosphazenes [(1-PhCH₂-4-Fc-C₂N₃) ₂PN](PNCl₂)₂ (13), [(1-PhCH₂-4-Fc- C₂N₃)(1-PhCH₂-5-Fc-C₂N ₃)PN](PNCl₂)₂] (14), and [(1-PhCH ₂-5-Fc-C₂N₃)₂PN](PNCl ₂)₂ (15), the unsymmetrically disubstituted bis-triazole compound 14 was found to be the major product. The fluorophosphazene-derived triazole 10 was found to readily form a disubstituted square-planar complex trans-[(1-PhCH₂-4-P₃N₃F₅-5-Fc)C ₂N₃]₂PdCl₂ (16) with PdCl ₂(PhCN)₂. All of the new ferrocene- and cyclophosphazene-derived compounds except 8 and 12 have also been structurally characterized.

Full text of DOI:10.1021/ic100703h

Inorg. Chem. 2010, 49, 5753–5765 5753
DOI: 10.1021/ic100703h
Synthesis and Reactions of Ethynylferrocene-Derived Fluoro- and
Chlorocyclotriphosphazenes
Karunesh Keshav, Nem Singh, and Anil J. Elias*
Department of Chemistry, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110016, India
Received April 12, 2010
The reactions of lithiated ethynylferrocene, FcCtCLi (Fc = ferrocenyl), with fluoro- and chlorocyclotriphosphazenes, N3P3X6
(X = F, Cl), resulted in the formation of stable mono-FcCtCP3N3X5 [X = F (1), Cl (2)] and geminal bis[(FcCtC)2PN]-
(X2PN)2 [X=F (3), Cl (4)], ethynylferrocene-substituted cyclophosphazenes. The reactions of 1 and 2 with CpCo(COD) were
found to differ in the nature of the sandwich compounds (η5-Cp)Co{η4-C4[Fc2(N3P3X5)2]} formed. While the fluoropho-
sphazene-derived compound 1 yielded both cis and trans isomers of the cyclobutadiene complexes 5 and 6, the chlo-
rophosphazene-derived compound 2 was found to give only the trans-cyclophosphazene-disubstituted cyclobutadiene
compound 7. The reaction of 3 with CpCo(COD) was found to give the compound (η5-Cp)Co{η4-C4-1,3-(Fc)2-2,4-[NP-
(CtCFc)(NPF2)2]2} (8) having one of the alkyne units of the cyclophosphazene moiety of 3 remaining unreacted even after
reaction with an excess of CpCo(COD). The first click reactions of ethynylferrocene-derived cyclophosphazenes have been
carried out by reacting 1 and 4 with benzyl azide, resulting in novel mono- and disubstituted cyclophosphazene-derived 1,2,3-
triazoles. The reaction of 1 with benzyl azide yielded two positional isomers of the 1,2,3-triazole, (1-PhCH2, 4-Fc, 5-P3-
N3F5)C2N3 (9), and (1-PhCH2, 4-P3N3F5, 5-Fc)C2N3 (10), with the latter having a benzyl group in the vicinity of the ferrocene
unit as the major product. A similar reaction of 4 with benzyl azide was found to yield five triazole-based products, with two,
[(1-PhCH2-4-FcC2N3)(CtCFc)PN](PNCl2)2 (11) and [(1-PhCH2-5-Fc-C2N3)(CtCFc)PN](PNCl2)2 (12), having one
unreacted alkyne unit in the molecule. Among the bis-triazole-derived chlorophosphazenes [(1-PhCH2-4-Fc-C2N3)2PN]-
(PNCl2)2 (13), [(1-PhCH2-4-Fc-C2N3)(1-PhCH2-5-Fc-C2N3)PN](PNCl2)2] (14), and [(1-PhCH2-5-Fc-C2N3)2PN](PNCl2)2
(15), the unsymmetrically disubstituted bis-triazole compound 14 was found to be the major product. The fluorophosphazene-
derived triazole 10 was found to readily form a disubstituted square-planar complex trans-[(1-PhCH2-4-P3N3F5-5-Fc)C2-
N3]2PdCl2 (16) with PdCl2(PhCN)2. All of the new ferrocene- and cyclophosphazene-derived compounds except 8 and 12
have also been structurally characterized.
Introduction
and as multidentate and multianionic ligands.1 Among the
known derivatives of cyclophosphazenes, those having P-N
or P-O bonds dominate, with relatively lesser examples
of P-C-bonded compounds.2-7 While P-aryl-substituted
The uniqueness of halogenated cyclophosphazenes among
inorganic heterocycles stems from the fact that their reactive
P-X bonds can be made to undergo a wide variety of substi-
tution reactions, leading to derivatives with diverse application
potential. The potential applications of cyclophosphazenes and
their derivatives include their use as stable cores for preparing
dendrimers, as precursors for phosphazene-based polymers,
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*To whom correspondence should be addressed. E-mail: eliasanil@gmail.com.
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2007, 251, 1045–1074. (b) Chandrasekhar, V.; Krishnan, V. Adv. Inorg. Chem.
2002, 53, 159–173. (c) Allcock, H. R. Chemistry and Applications of Polypho-
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r
2010 American Chemical Society
Published on Web 05/27/2010
pubs.acs.org/IC

5754 Inorganic Chemistry, Vol. 49, No. 12, 2010
Keshav et al.
cyclophosphazenes are readily prepared by the Friedel-Crafts
reaction, realizing derivatives with alkyl, alkenyl, or alkynyl
groups is more difficult, often requiring organometallic reagents
or the direct synthesis of cyclophosphazene from substituted
phosphorus precursors.8 The pioneering work by Allen and
co-workers has shown that alkynyl derivatives of cyclophos-
phazenes, which are useful precursors for a host of new
phosphazene-derived compounds, is accessible by the reaction
of halocyclophosphazenes with organolithium reagents.9 The
known phosphazene-derived alkynes have so far been res-
tricted to those having phenyl, p-tolyl, n-butylethynyl, and tri-
methylsilyl units, with most of them derived from N3P3F6.9a,10
We as well as others have shown the usefulness of arylethynyl
derivatives of cyclophosphazenes in realizing novel cyclopho-
sphazene-derived organoiron and organocobalt clusters as
well as cobalt sandwich compounds and metallacycles.11
Ferrocene-derived alkynes are established structural motifs in
synthetic organometallic chemistry and material science.12
Functionalized ferrocenylalkynes have been utilized for the
introduction of electroactivity on substrates especially oligo-
mers, polymers, and dendrimers.13,14 Their utility in making
materials with nonlinear optical properties and in preparing
nucleobase receptors is well documented.15,16 Although few
examples of ferrocene-derived cyclophosphazenes are known,17
we have for the first time explored the possibility of introducing
ferrocenylalkyne units on the phosphazene core and report
herein the synthesis and structural characterization of the first
examples of mono(ethynylferrocenyl)- and geminal bis(ethynyl-
ferrocenyl)-derived fluoro- and chlorocyclophosphazenes. The
differences in reactivity of the ethynylferrocene-derived chloro-
and fluorophosphazenes with the cobalt half-sandwich com-
pound CpCo(COD) have been described. We also report the
synthesis and structural studies of the first examples of cyclo-
phosphazene-derived 1,2,3-triazoles prepared by click reactions
of the new ethynylferrocene-derived fluoro- and chlorophos-
phazenes with benzyl azide. The usefulness of these cyclo-
phosphazene-derived 1,2,3-triazoles as ligands has also been
demonstrated by preparing a palladium complex of the triazole.
Results and Discussion
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The reactions of lithiated ethynylferrocene with hexafluoro-
and hexachlorocyclotriphosphazenes were found to proceed at
-78 °C with the formation of mono(ethynylferrocenyl)- and
geminal bis(ethynylferrocenyl)-derived fluoro- and chloropho-
sphazenes 1-4 (Schemes 1 and 2). The orange, air-stable com-
pounds were purified easily by column chromatography. Inte-
restingly, the reactions carried out in a 1:1 molar ratio resulted
in the formation of both mono(ethynylferrocenyl) and geminal
bis(ethynylferrocene) derivatives, with 1 being the major pro-
duct in the case of N3P3F6 and 4 being the major product in the
case of N3P3Cl6. Maximum yields of 1 and 2 were obtained in a
2:1 molar ratio reaction of N3P3X6 and FcCtCLi, while the
geminal disubstituted derivatives 3 and 4 were obtained best
from a 1:2 molar ratio of N3P3X6 and FcCtCLi. The reactions
carried out with a view to realize more substitution on the phos-
phazene ring were found to result in decomposition products
with traces of disubstituted derivatives. In general, compared to
N3P3F6, the reactions involving N3P3Cl6 gave lesser yields of
the alkyne derivatives, often giving unreacted N3P3Cl6 as well
as the dimer of ethynylferrocene as side products.
The reaction of 1 with CpCo(COD) in refluxing toluene was
found to give CpCo-derived cyclobutadiene sandwich com-
pounds of the type (η5-Cp)Co[η4-C4(Fc)2(N3P3F5)2] having
both cis- and trans-substituted phosphazene-derived cyclo-
butadiene units. The trans-disubstituted compound 5 was the
major product whose basic structural features were similar to
those of [η5-MeOC(O)Cp]Co[η4-C4(Ph)2(N3P3F5)2] reported
earlier from the reactions of [MeOC(O)Cp]Co(PPh3)2 and
PhCtCN3P3F5.18 The minor cis-disubstituted cyclobutadiene
compound 6 was a unique example of its kind, which has not
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Article
Inorganic Chemistry, Vol. 49, No. 12, 2010 5755
Scheme 1
Scheme 2
Scheme 3
Scheme 4
been observed to form in the reactions of CpCo(PPh3)2 or
CpCo(CO)2 with fluorophosphazene-derived phenylacetylene.
In contrast, the reaction of 2 with CpCo(COD) resulted exclu-
sively in the formation of the trans-disubstituted cyclobutadiene
derivative (η5-Cp)Co[η4-C4(Fc)2(N3P3Cl5)2] (7; Scheme 3).
The reaction of geminal ethynylferrocene-disubstituted
fluorophosphazene 4 with an excess of CpCo(COD) was
found to result in (η5-Cp)Co{η4-C4-1,3-(Fc)2-2,4-[NP(Ct
CFc)(NPF2)2]2} (8), having two unreacted ethynylferrocene
units on the fluorocyclophosphazene moieties (Scheme 4).
The Huisigen 3 þ 2 cycloaddition reactions, commonly
known as click reactions, involve the reaction of an azide with
alkynes, resulting in the formation of substituted 1,2,3-triazoles.
We were interested in observing the feasibility of such reactions
of cyclophosphazene-derived alkynes and carried out the first
click reactions of the fluoro- and chlorophosphazene-derived
alkynes 1 and 4 with benzyl azide in refluxing toluene. The
reaction of 1 with PhCH2N3 resulted in two positional isomers
of the 1,2,3-triazoles (1-PhCH2, 4-Fc, 5-P3N3F5)C2N3 (9) and
(1-PhCH2, 4-P3N3F5, 5-Fc)C2N3 (10) (Scheme 5). Compound
10, having the benzyl group in the vicinity of ferrocenyl unit, was
obtained as the major product.
The reaction of the geminal bis(ethynylferrocene)-substi-
tuted chlorophosphazene 4 with benzyl azide gave five
products having triazole units that were carefully separated,
purified, and structurally characterized (Scheme 6). Com-
pounds 11 and 12 were positional isomers of the triazole
having one of the ethynylferrocene units remaining intact.
Compounds 13-15 were two triazole units, with 13 having
benzyl and ferrocenyl units symmetrically substituted in the 1
and 4 positions of the triazole and 15 having the same groups
symmetrically substituted at the 1 and 5 positions of the
triazole. Compound 14, which was the major product among
the bis-triazolecompounds, wasfound to beunsymmetrically

5756 Inorganic Chemistry, Vol. 49, No. 12, 2010
Keshav et al.
Scheme 5
Scheme 6
Scheme 7
substituted ,with one triazole ring having 1,4 and the other
1,5 substitution of the benzyl and ferrocenyl groups.
The utility of substituted phosphazenes, especially as
multidentate ligands in coordination chemistry, is well docu-
mented.1a,b We were keen to explore the possibility of using
the phosphazene- and ferrocene-derived 1,2,3-triazoles as
ligands in coordination chemistry. A 2:1 molar reaction of
the fluorophosphazene-derived triazole 10 with PdCl2(Ph-
CN)2 resulted in the exclusive formation of a square-planar
palladium complex, trans-[(1-PhCH2-4-P3N3F5-5-Fc)C2N3]2-
PdCl2 (16; Scheme 7).
and 19F), and mass spectral studies. The 1H NMR
chemical shifts for the unsubstituted cyclopentadienyl
units of compounds 1-4 were found to be in the range
of 4.23-4.32 ppm, whereas the R protons of the substi-
tuted cyclopentadienyl were located downfield in the
range of 4.57-4.68 ppm. The cyclopentadiene ring at-
tached to the cobalt metal center in compounds 5-8 gave
a singlet in the range of 4.85-5.08 ppm. Both CH2
groups, which were attached to the triazole ring, gave
two different signals at 5.96 and 6.10 ppm in 14 because of
different chemical environments, which was in contrast to
13 and 15, which gave single peaks for these CH2 groups
at 5.80 and 5.94 ppm, respectively.
Spectral Studies of Compounds 1-16. Compounds
1-16 have been characterized by IR, NMR (1H, 13C, 31P,

Article
The 31P NMR chemical shifts of the ethynylferrocene-
substituted phosphorus atom of the cyclophosphazene rings
were found to undergo significant changes on derivatization
of the alkynes. While the chemical shift of the ethynylferro-
Inorganic Chemistry, Vol. 49, No. 12, 2010 5757
2148-2179 cm-1. The νNdN stretching frequencies for all
triazole-containing compounds were found to be between
1545 and 1552 cm-1 and were comparable to those ob-
served for other reported 1,2,3- triazole heterocycles.20
The 19F NMR spectra of compounds 1, 3, 5, 6, 8-10, and
16 gave signals between -64.43 and -69.63 ppm for PF2
groups and between 42.05 and 48.08 ppm for the PF(C)
moiety. This chemical shift is consistent with previously
reported ethynyl-derived fluorophosphazene-9a and fluoro-
phosphazene-substituted metallocenes and metallacycles.18
19F NMR spectra of compounds 1, 5, 6, 8-10, and16 showed
two sets of doublet of multiplets at different chemical shifts for
the PF2 groups (1JP-F ∼ 750-970 Hz) because of the dia-
stereotopic nature of the fluorine atoms of the N3P3F5 units.
Electrochemical Studies. The redox properties of the
ferrocenyl units of some of the new compounds were studied
by cyclic voltammetry using 0.1 M tert-butylammonium
perchlorate in dichloromethane as the supporting electrolyte
with a scan rate of 50-100 mV. The potential of the Fc/Fcþ
couple under experimental conditions was 0.10 V (80 mV) vs
Ag/Agþ. The cyclic voltammograms of 1-4 exhibited only
one reversible redox wave, despite having the presence of two
ferrocene units in 3 and 4, indicating that both of these
ferrocene units are in the same chemical environment, an
observation supported by X-ray crystallography. Similar
electrochemical behaviors were reported in the cases of
(FcCtC)2PhP and (FcCtC)3P.21 Compounds 5-7 having
two ferrocenyl units in the molecule indicated the presence of
two redox waves in their cyclic voltammograms in the
half-wave potential range of E1/2 = 0.21-0.44 V. The nature
of these cyclic voltammograms was found to be similar as
that of the previously reported (η5-Cp)Co{η4-[C4(C5H5)2-
(Fc)2]}.22 In the case of the chlorophosphazene-derived
compound 7, the separation between the two redox peaks
(at 0.24 and 0.38 V) was found to be more noticeable in
comparison to the fluorophosphazene-derived compounds 5
and 6. The monoferrocenyl compounds 9 and 10 showed
reversible redox waves with E1/2 at 0.28 and 0.46 V, respec-
tively. The diferrocenyl compounds 8, 11, and 14 showed
two separate oxidation waves having chemical reversibility
(E1/2 = 0.23 and 0.43 V for 8; E1/2 = 0.25 and 0.44 V for 11;
E1/2=0.23 and 0.46 V for 14). Oxidation waves at E1/2 =0.43
and 0.44 V in the case of 8 and 11 were due to the ethynyl-
ferrocene units. Compound 14 showed two different redox
peaks due to the different chemical environments around the
two ferrocene units, while observation of a single peak in the
case of 13 and 15 indicated similar chemical environments
around both of the ferrocene units, which was substantiated
from single-crystal X-ray structural analysis. The palladium
complex 16 showed a reversible oxidation wave for the ferro-
cene units at E1/2 =0.54 V, slightly higher than the parent
triazole 10 because of the decreased electron density at the
ferrocene moieties, caused by complexation of the triazole
ring nitrogen atom with the palladium center.
cene-bound PF unit of 1 was observed at 3.79 ppm (JPF
=
920 Hz), δ values of the trans and cis-cyclobutadiene-disub-
stituted cobalt sandwich compounds 5and 6, derivedfrom1,
were observed at 35.48 and 37.55 ppm, respectively. The
chemical shift of the same phosphorus atom in the analogous
trans-fluorophosphazene-disubstituted compound (η5-CH3-
OC(O)C5H4)Co{η4C4[1,3-(N3P3F5)2-2,4-(Ph)2]}18 was ob-
served at 32.44 ppm. Similar changes in the 31P NMR
chemical shifts were also observed for the phosphazene-
derived triazoles as well. The two positional isomers 9 and 10
of the fluorophosphazene-derived 1,2,3-triazole gave reso-
nances for the triazole-bound P-F units at 20.08 and 24.70
ppm, respectively. Upon formation of the square-planar
palladium complex 16, the 31P NMR δ value of the triazole-
bound P-F unit of 10 was found to shift from 24.70 to
20.65 ppm. The 31P NMR δ value of the dialkyne-bound
phosphorus atom of 3 was observed at -24.83 ppm, while
for its partially CpCo cyclobutadiene-derived derivative 8, it
was found to shift to 0.65 ppm. In contrast, only minimal
changes in the range of 6.63-7.91 ppm were observed in the
31P NMR chemical shifts of the PF2 units of all fluoropho-
sphazene-derived compounds in the present study.
Similar shifts in the 31P NMR δ values were also observed
for the chlorophosphazene-derived alkynes and their deri-
vatives. The chemical shift of the P(Cl)(CtCFc) unit of
the mono-substituted chlorophosphazene-derived alkyne 2,
upon conversion to the CpCo cyclobutadiene-derived sand-
wich compound 7, was found to shift from -5.28 to þ27.41
ppm. The P(CtCFc)2 unit of compound 4, which showed a
resonance at -33.18 ppm, underwent a considerable down-
field shift after the formation of triazoles. The mixed triazole-
and alkyne-substituted compounds 11 and 12 resonated at a
higher field in comparison to compounds 13-15 because of
the shielding nature of the ethynyl units. Triazole-substituted
phosphorus atoms in compounds 13-15 resonated at -6.67,
-1.80, and þ0.94 ppm, respectively. The triazole-substituted
phosphorus atom in compound 13 resonated slightly upfield
in comparison to those of 14 and 15 because of its proximity
to the electron-rich sp3-hybridized nitrogen atoms.
13C NMR analysis of the ethynylferrocene-derived
chloro- and fluorophosphazenes 1-4 indicated the presence
of one of the alkyne carbon atoms in the range of 104-107
ppm and the other carbon in the range of 79-83 ppm, which
agreed with the reported 13C NMR value of (FcCtC)2-
PhPdSe,19a where chemical shifts were reported at 106.3 and
79.5 ppm. Cyclobutadiene ring carbon atoms of the cobalt
sandwich compounds 5-8 resonated in the range of 83.50-
86.00 ppm, which agrees well with the 13C NMR δ values
reported for the C4 ring of (η5-CH3OC(O)C5H4)Co{η4-C4-
[1,3-(N3P3F5)2-2,4-(Ph)2]}.18 The 13C NMR δ values of
the ring carbon atoms of the five-membered triazole rings
of compounds 9-16 were observed in the expected range of
141.70-155.55 ppm.
The νCꢀC stretching frequency for compounds 1- 4, 8,
11, and 12 were found to be in the range of 2152-2176
cm-1. This corresponds to the νCꢀC stretching frequency
reported in the case of ethynylferrocenyl compounds
(FcCtC)2PhPdSe, (FcCtC)3PdSe,19a and N3P3[CtC-
( p-Tol)]2Cl4,10a where it was observed in the range of
(19) (a) Jakob, A.; Milde, B.; Ecorchard, P.; Schreiner, C.; Lang, H.
J. Organomet. Chem. 2008, 693, 3821–3830. (b) Jakob, A.; Ecorchard, P.;
Linseis, M.; Winter, R. F.; Lang, H. J. Organomet. Chem. 2009, 694, 655–666.
(20) Kamalraj, V. R.; Senthil, S.; Kannan, P. J. Mol. Struct. 2008, 892,
210–215.
(21) Baumgartner, T.; Fiege, M.; Pontzen, F.; Muller, R. A. Organo-
metallics 2006, 25, 5657–5664.
(22) Kotz, J.; Neyhart, G.; Vining, W. J.; Rausch, M. D. Organometallics
1983, 2, 79–82.

5758 Inorganic Chemistry, Vol. 49, No. 12, 2010
Keshav et al.
Figure 1. Molecular structure of compound 1 (hydrogen atoms have
been omitted for clarity).
Figure 4. Molecular structure of compound 4 (hydrogen atoms have
been omitted for clarity).
1-4,theP-N bond distances involving the ethynylferrocene-
substituted phosphorus atoms were found to be in the
˚
range of 1.568(6)-1.595(4) A, which were longer than the
Figure 2. Molecular structure of compound 2 (hydrogen atoms have
been omitted for clarity).
other P-N bonds for both chloro- and fluoro-substituted
˚
cyclophosphazene units in 1-4 [1.530(4)-1.574(3) A].
Similarly, N(1)-P(1)-N(1) angles in 2-4 and the N(1)-
P(1)-N(3) angle in 1 (mean value 116.13°) were found to be
narrower than the other N-P-N angles of compounds
1-4. These variations were found to be more noticeable in
the geminal bis(ethynylferrocenyl)-derived cyclophospha-
zenes 3 and 4 and can be attributed to the greater electron
donation by the two alkynyl groups to the phosphorus
atom. Similar variations were observed in the crystal struc-
tures of several mono- and diorgano-substituted cyclotri-
phosphazenes.10a,23 The P-C bond distances in compounds
˚
1-4were in the range of 1.705(8)-1.726(3) A, andtheCtC
triple bond distances in 1-4 were between 1.189(7) and
1.194(10) A. These distances were similar to those found in
˚
phosphorus-based ferrocenylalkynes (FcCtC)3PdO and
(FcCtC)3PdSe.19a The ethynyl units show deviation from
linearity with P(1)-C(1)-C(2) angles of 178.6(7)° (1),
166.7(5)° (2), 176.5(5)° (3), and 176.7(3)° (4). A similar devi-
ation from linearity in the range 167.9(2)-175.6(3)° has been
reported for (FcCtC)3P, (FcCtC)3PdO, and (FcCtC)-
3PdSe.19 In contrast, the C(1)-C(2)-C(3) angles for 1-4
were found to be almost linear [177.3(8)°, 179.5(4)°,
177.8(6)°, and 177.9(4)°, respectively]. These bond angles
were found to vary in the range 176.4(3)-180.0(3)° for
(FcCtC)3P and (FcCtC)3PdSe.19a
X-ray Crystal Structures of Compounds 5-7. The crystal
structures of compounds 5-7 are given in Figures 5-7. The
structure of 6 given in Figure 6 shows the occurrence of two
different molecules (A and B) within the asymmetric unit. In
compound 5, the two pentafluorophosphazene units bound
to the cyclobutadiene ring were trans to each other. The phos-
phazene units were gauche to each other in 5-7. For com-
pounds 5-7, mean planes containing the two phosphazene
Figure 3. Molecular structure of compound 3 (hydrogen atoms have
been omitted for clarity).
X-ray Crystal Structures of Compounds 1-4. The crystal
structures of compounds 1-4 are given in Figures 1-4. The
fluorophosphazene ring was found to be in an almost
planar geometry in 1 and 3 because the phosphorus atoms
bearing the ethynylferrocene groups do not deviate signifi-
cantly from the mean plane defined by the other four atoms
of the phosphazene ring. In contrast, the N3P3 ring of the
chlorophosphazene-derived alkyne 2 was clearly in a chair
conformation, with P(1) and N(2) deviating from the mean
plane defined by the other four ring atoms by þ0.204(1) and
˚
-0.123(5) A, respectively. In compound 4, the N3P3 ring
(23) (a) Allcock, H. R.; Brennan, D. J.; Graaskamp, J. M.; Parvez, M.
Organometallics 1986, 5, 2434–2446. (b) Allcock, H. R.; Brennan, D. J.; Dunn,
B. J.; Parvez, M. Inorg. Chem. 1988, 27, 3226–3233. (c) Mani, N. V.; Ahmed,
F. R.; Barnes, W. H. Acta Crystallogr. 1965, 19, 693–698.
was found to be in a twist-boat form, which is in contrast
to the chair configuration reported for geminal bis(p-tolyl-
ethynyl)tetrachlorocyclotriphosphazene.10a In compounds

Article
Inorganic Chemistry, Vol. 49, No. 12, 2010 5759
units intersect each other at angles of 35.4(1)°, 73.6(1)°
[71.9(1)°], and 74.5(1)°, respectively. The mean plane of the
phosphazene units makes angles of 42.4(1)° and 58.1(1)°
in 5, 40.6(2)° [41.5(2)°] and 74.7(2)° [76.0(2)°] in 6, and
41.2(2)° and 33.6(2)° in 7, with the mean plane passing
through the cyclobutadiene ring. In 5 and 7, the two
ferrocene units were cis with respect to the cyclobutadiene
ring of the cobalt sandwich unit, which was in contrast to
compound 6, where the two ferrocene units were found
to be oriented nearly perpendicular to each other, with
the substituted Cp rings making an angle of 74.2(3)°
[72.1(3)°] between them. Mean planes passing through
the substituted cyclopentadiene rings of the ferrocene
units of 5 and 7 make relatively small angles [9.8(3)
-22.1(3)°] with the mean plane passing through the
cyclobutadiene unit. In contrast, these angles were found
to be 20.6(3)° [16.7(3)°] and 55.7(3)° [56.7(4)°] for 6.
Porous molecular materials attract lot of attention because
of their extensive application in heterogeneous catalysis.
The crystal structure of compound 7 features voids that
can possibly accommodate small molecules (Figure 8).
These voids are a result of the weak C-H π(Cp) and
3 3 3
Figure 7. Molecular structure of compound 7 (hydrogen atoms and the
solvent molecule have been omitted for clarity).
Figure 8. Crystal packing diagram of compound 7 showing voids and
weak interactions (hydrogen atoms that are not involved in intermole-
cular interactions have been omitted for clarity).
Figure 5. Molecular structure of compound 5 (hydrogen atoms have
been omitted for clarity).
Figure 6. Molecular structure of compound 6 (hydrogen atoms have been omitted for clarity).

5760 Inorganic Chemistry, Vol. 49, No. 12, 2010
Keshav et al.
Figure 9. Molecular structure of compound 9 (hydrogen atoms have
been omitted for clarity).
Figure 11. Molecular structure of compound 11 (hydrogen atoms have
been omitted for clarity).
Figure 10. Molecular structure of compound 10 (hydrogen atoms have
been omitted for clarity).
P-Cl H interactions found between the cyclopenta-
3 3 3
dienyl rings and the cyclophosphazenyl units.
X-ray Crystal Structures of Compounds 9-11 and
13-15. The crystal structures of compounds 9-11 and
13-15 are given in Figures 9-14. The CdC bond dis-
tances of triazole rings vary in these compounds in the range
Figure 12. Molecular structure of compound 13 (hydrogen atoms and
the solvent molecule have been omitted for clarity).
˚
from 1.380(5) to 1.393(8) A, and the NdN bond distances of
˚
the triazole unit vary in the range of 1.296(5)-1.323(5) A,
which agree with analogous distances for the reported struc-
ture of monoferrocenyltriazole.24 For the isomeric mono-
triazolyl compounds 9 and 10, the bond distances and angles
of the triazole ring were found to be almost identical, but
the orientations of P3N3F5 and the substituted cyclopenta-
diene ring of ferrocene with respect to the triazole ring were
different. The angles between the mean plane of the triazole
and the Cp rings to which they are attached were found to be
6.1(2)° for 9 and 22.4(2)° for 10, whereas the angles between
the mean plane of the triazole and the P3N3F5 ring were
found to be 59.2(1)° and 69.2(2)°, respectively.
The CtC bond distance for compound 11 was found to
˚
be 1.196(1) A, which is comparable to that of the related
compound (FcCtC)P(Ph)2.19a The angle P(1)-C(20)-
C(21) was found to be 165.0(5)° in 11, which corresponds
ꢀ
(24) Badeche, S.; Daran, J. C.; Ruiz, J.; Astruc, D. Inorg. Chem. 2008, 47,
4903–4908.
Figure 13. Molecular structure of compound 14 (hydrogen atoms have
been omitted for clarity).

Article
Inorganic Chemistry, Vol. 49, No. 12, 2010 5761
very well [165.1(13)°] to similar angles in the ferrocene-
derived alkyne-phosphine complex [(FcCtC)3P]2Pd-
Cl2.19a The mean plane passing through the triazole ring
makes angles of 12.3(2)° and 49.3(2)° with the substituted
cyclopentadienyl unit of ferrocene and the phosphazene
ring, respectively.
The angles between the mean planes passing through the
two triazole rings were found to be in the range of 67.6(1)-
73.0(1)°. The angles between the mean plane of the P3N3Cl4
unit and the two geminal triazole rings were found to be
58.0(1)° and 60.5(1)° in 13, 70.6(1)° and 60.0(1)° in 14, and
77.0(1)° in 15. The angles between the triazole and the Cp
ring with which it is attached were found to be 71.5(1)° and
73.8(1)° in 13, 20.5(1)° and 10.5(1)° in 14, and 43.5(1)° in 15.
In the structure of 13, a solvated ethyl acetate molecule was
also found in the crystal lattice.
to be 59.2(1)° in 9 and 69.2(2)° in 10. Analogous angles for
the chlorophosphazene-derived triazoles were found to
be 49.3(1)° in 11, 60.4(1)° and 57.9(1)° in 13, 70.6(1)° and
59.9(1)° in 14, and 77.0(1)° in 15.
X-ray Crystal Structure of Compound 16. The crystal
structure of compound 16 is given in Figure 15. In 16, two
molecules of the fluorophosphazene-derived triazole 10 form
a square-planar complex, with the triazole rings oriented
trans to each other. Interestingly, the nitrogen atom that was
at the β position with respect to the electron-withdrawing
fluorophosphazene unit readily takes part in coordination.
Coordination to palladium through the N(6) atom of the
triazole did not affect significantly the geometry of the
triazole ring, but there was a change in the orientation of
P3N3F5 and the ferrocene units with respect to the triazole
ring. Pd-N(6) and Pd-Cl(1) were found to be 2.020(3) and
˚
The angles between the mean plane of the triazole ring
and the plane defined by ring atoms of P3N3F5 were found
2.288(2) A, which were similar to analogous distances in a
recently reported monoferrocenyltriazole complex.24 The
dihedral angle between the mean plane of the triazole ring
and the Cp connected to it changed from 22.4(2)° to 38.2(2)°
after forming the palladium complex. In addition, the di-
hedral angle between the triazole and P3N3F5 changed to
58.8(1)° from 69.2(2)° of the triazole. The dihedral angle
between the triazole ring and the palladium square plane was
found to be 55.9(2)°. Two solvated molecules of chloroform
were also found to be present in the crystal lattice.
Conclusion
The first examples of mono(ethynylferrocene)- and gemi-
nal bis(ethynylferrocene)-derived fluoro- and chlorophos-
phazenes have been synthesized and structurally character-
ized. The reactions of these alkynes with CpCo(COD) were
found to show interesting differences, with the fluoropho-
sphazene-derived alkyne FcCtCP3N3F5 yielding both cis and
trans isomers of the cyclobutadienecobalt complexes of the
type (η5-Cp)Co{η4-C4[Fc2(N3P3F5)2]} and the chloropho-
sphazene analogue, FcCtCP3N3Cl5, giving exclusively the
trans-cyclobutadiene-substituted product. The reaction of
the geminal bis(ethynylferrocene)-derived fluorophosphazene
Figure 14. Molecular structure of compound 15 (hydrogen atoms have
been omitted for clarity).
Figure 15. Molecular structure of compound 16 (hydrogen atoms and solvent molecules have been omitted for clarity).

5762 Inorganic Chemistry, Vol. 49, No. 12, 2010
Keshav et al.
Table 1. X-ray Crystallographic Data for Compounds 1-4
1
2
3
4
empirical formula
fw
space group
C12H9F5FeN3P3
438.98
Pca21
20.224(4)
10.136(2)
7.9972(17)
90.00
C12H9Cl5FeN3P3
521.23
P21/m
8.1060(13)
9.3159(15)
13.322(2)
90.00
C24H18F4Fe2N3P3
629.02
C2/c
15.469(4)
19.649(4)
10.899(3)
90.00
C24H18Cl4Fe2N3P3
694.82
C2/c
15.993(3)
20.501(3)
11.1149(17)
90.00
˚
a (A)
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
90.00
90.00
105.453(2)
90.00
130.422(3)
90.00
130.846(2)
90.00
3
˚
V (A )
Z
T (K)
1693.4(6)
4
293(2)
0.710 73
1.779
1.264
969.6(3)
2
293(2)
0.710 73
1.785
1.715
2522.0(10)
4
293(2)
0.710 73
1.657
1.390
2756.9(7)
4
293(2)
0.710 73
1.674
1.635
˚
λ (A)
F
calcd (g/cm3)
μ (mm-1
θ range
)
1.96-25.00
0.0623, 0.1335
2.61-25.00
0.0395, 0.1037
2.02-23.50
0.0558, 0.1246
1.95-25.50
0.0383, 0.0897
R1a, wR2b [I > 2σ (I)]
P
P
P
a R1 = ||Fo| - |Fc||/ |Fo|. b wR = {[ (|Fo|2|Fc|2)2]}1/2
.
Table 2. X-ray Crystallographic Data for Compounds 5-7, 9, and 10
5
6
7
9
10
empirical formula
fw
space group
C29H23CoF10Fe2N6P6
1001.98
P21/n
11.758(2)
16.499(3)
18.172(4)
90.00
C29H23CoF10Fe2N6P6
1001.98
P1
C29H23CoCl10Fe2N6P6,C3
1202.52
P21/c
7.3106(11)
22.024(3)
19.681(3)
90.00
C19H16F5FeN6P3
572.14
P1
C19H16F5FeN6P3
572.14
P21/c
15.181(2)
8.5883(13)
18.934(3)
90.00
˚
a (A)
13.050(2)
13.242(2)
21.410(3)
106.769(3)
95.080(3)
90.957(3)
3524.7(10)
4
293(2)
0.710 73
1.888
1.638
7.532(3)
11.945(4)
14.564(5)
108.477(5)
98.823(6)
103.195(6)
1173.3(7)
2
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
94.498(3)
90.00
94.876(3)
90.00
109.710(3)
90.00
3
˚
V (A )
Z
T (K)
3514.4(12)
4
293(2)
0.710 73
1.894
1.642
3157.2(8)
4
293(2)
0.710 73
1.776
0.943
2324.0(6)
4
293(2)
0.710 73
1.635
0.916
293(2)
˚
λ (A)
0.710 73
1.620
0.907
1.52-25.50
0.0521, 0.1340
F
calcd (g/cm3)
μ (mm-1
θ range
)
1.67-24.00
0.0345, 0.0812
1.57-25.50
0.0844, 0.1830
1.65-25.50
0.0630, 0.1764
1.42-25.00
0.0756, 0.1507
R1a, wR2b [I > 2σ (I)]
P
P
P
a R1 = ||Fo| - |Fc||/ |Fo|. b wR = {[ (|Fo|2|Fc|2)2]}1/2
.
Table 3. X-ray Crystallographic Data for Compounds 11 and 13-16
11
13
14
15
16
empirical formula
C31H25 Cl4Fe2N6P3
C38 H32Cl4Fe2N9P3,
C4H8O2
1049.24
C38 H32Cl4Fe2N9P3
C38H32Cl4Fe2N9P3
C38H32Cl2Fe10Fe2-
N12P6Pd, 2(CHCl3)
1560.31
fw
space group
827.98
P21/n
15.187(4)
12.902(3)
17.846(4)
90.00
961.14
P1
961.14
C2/c
21.634(2)
16.0644(18)
13.7657(15)
90.00
P1
P1
˚
a (A)
12.1626(14)
12.9545(15)
15.2079(18)
84.723(2)
83.885(2)
76.853(2)
2314.4(5)
2
293(2)
0.71073
1.506
1.009
9.1867(16)
10.7009(19)
20.921(4)
90.512(3)
95.073(3)
95.919(3)
2037.4(6)
2
11.2154(12)
11.6282(12)
12.7845(13)
115.258(2)
97.712(2)
94.298(2)
1477.9(3)
1
293(2)
0.71073
1.753
1.384
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
101.052(4)
90.00
124.220(2)
90.00
3
˚
V (A )
Z
T (K)
3431.9(14)
4
293(2)
0.71073
1.602
1.330
3955.9(7)
4
293(2)
0.71073
1.614
1.168
293(2)
˚
λ (A)
0.71073
1.567
1.134
2.46-25.50
0.0618, 0.1364
F
calcd (g/cm3)
μ (mm-1
θ range
)
1.62-25.00
0.0763, 0.1627
1.62-25.50
0.0525, 0.1432
1.70-25.49
0.0359, 0.0861
1.79-25.50
0.0562, 0.1415
R1a, wR2b [I > 2σ (I)]
P
P
P
a R1 = ||Fo| - |Fc||/ |Fo|. b wR2 = {[ (|Fo|2|Fc|2)2]}1/2
.
[(FcCtC)2PN](F2PN)2 with an excess of CpCo(COD) gave
only the partial cycloadded product, with one of the alkyne
units remaining unreacted. Both the mono- and bis(ethynyl-
ferrocene)-derived fluoro- and chlorocyclophosphazenes un-
derwent click reactions with benzyl azide, yielding the first
example of phosphazene-derived mono- and geminal bis-1,2,3-
triazoles that were structurally characterized. The usefulness of
the triazole-derived cyclophosphazenes as novel nitrogen-based
ligands was demonstrated by preparing a trans-disubstitu-
ted square-planar complex of the fluorophosphazene-derived

Article
Inorganic Chemistry, Vol. 49, No. 12, 2010 5763
triazole (1-PhCH2, 4-P3N3F5, 5-Fc)C2N3 with palladium
dichloride.
787 s (P-F). 1H NMR: δ 4.32 [s, 5H, Cp], 4.42 (m, 2H, -CH),
4.68 (m, 2H, -CH). 13C{1H} NMR: δ 57.54 (d, J(C,P) = 7 Hz,
Cp1), 70.66 (s, Cp), 70.98 (s, Cp2/5), 72.95 (s, Cp3/4), 82.16 (s, CtC),
106.20 [d, J(C,P) =63Hz,CtC]. 31P{1H} NMR: δ3.79 [d, JP-F
=
Experimental Section
920 Hz, -PF(CtCFc)], 7.52 [t, JP-F=837 Hz, -PF2]. 19F{1H}
NMR: δ -69.06 (dm, 2F, JP-F = 835 Hz, -PF2), -67.61 (dm, 2F,
JP-F=844 Hz, -PF2), -43.25 [dm, 1F, JP-F=917 Hz, -PF(Ct
CFc)]. MS (ESI) [m/e (species)]: 439.90 [M þ 1]þ. Anal. Calcd for
C12H9F5N3P3: C, 32.83; H, 2.07; N, 9.57. Found: C, 33.09; H, 2.20;
N, 9.44. E1/2 = 0.52 V vs ferrocene, reversible.
General Methods. All manipulations of the complexes were
carried out using standard Schlenk techniques under a nitrogen
atmosphere. Tetrahydrofuran (THF) and toluene were freshly
distilled from sodium benzophenone ketyl under a nitrogen
atmosphere and used. CpCo(COD),25 ethynylferrocene,26 hexa-
fluorocyclotriphosphazene,27 and benzyl azide,28 were prepared
according to literature procedures. PdCl2(PhCN)2, N3P3Cl6,
and n-BuLi (1.6 M in hexanes) were procured from Aldrich
and used as such.
Preparation of FcCtCP3N3Cl5. Following a synthetic proce-
dure similar to that outlined for FcCtCP3N3F5, ethynylferrocene
(0.50 g, 2.38 mmol) was reacted with N3P3Cl6 (1.60 g, 4.60 mmol) at
-78 °C. Afterward, all of the solvents were evaporated off, and the
crude product was purified through a silica gel column. The first and
second fractions that were obtained with hexane were identified as
unreacted hexachlorocyclotriphosphazene and ethynylferrocene
(0.20 g), respectively. The compound obtained upon elution with
ethyl acetate/hexane (2%), followed by slow evaporation as orange-
red crystals, was characterized as FcCtCP3N3Cl5 (2). Yield: 0.20 g
(20%). Mp: 120-122 °C. IR (ν, cm-1): 2154 m (CtC), 1198 vs
(PdN), 605 m (PdN), 523 m (P-Cl). 1H NMR: 4.32 (s, 5H, CpH),
4.42 (m, 2H, -CH), 4.68 (m, 2H, -CH). 13C{1H} NMR: δ 57.76
(d, Cp1), 70.67 (s, Cp), 71.07 (s, Cp2/5), 73.01 (s, Cp3/4), 81.06
(s, CtC), 106.42 [d, J(C,P)=65Hz, CtC]. 31P{1H} NMR: δ-5.28
[t, J=47 Hz, -PCl(CtC-Fc)], 20.01 (d, J=46 Hz, -PCl2).
MS (ESI) [m/e (species)]: 517.80 [M - 1]þ. Anal. Calcd for
C12H9Cl5FeN3P3: C, 27.65; H, 1.74; N, 8.06. Found: C, 28.24;
H, 1.79; N, 7.87. E1/2 = 0.50 V vs ferrocene, reversible.
Instrumentation. The 1H, 13C{1H}, 31P{1H}, and 19F{1H}
NMR spectra were recorded on a Bruker Spectrospin DPX-
300 NMR spectrometer at 300.13, 75.47, 121.48, and 282.37
MHz, respectively, using CDCl3 as the solvent. IR spectra in the
range 4000-250 cm-1 were recorded on a Nicolet Protege 460
ꢁ
FT-IR spectrometer as KBr pellets. Elemental analyses were
carried out on a Carlo Erba CHNSO 1108 elemental analyzer.
Mass spectra were recorded in the fast-atom-bombardment
mode using a JEOL SX 102/DA-6000 mass spectrometer and
in the time-of-flight mass spectrometry mode (HRMS) using an
AB Sciex spectrometer (model 1011273/A).
X-ray Crystallography. Suitable crystals of compounds 1-7,
9-11, 13-15, and 16 were obtained by slow evaporation of their
saturated solutions in ethyl acetate/hexane and chloroform/
hexane solvent mixtures, respectively. The single-crystal diffrac-
tion studies were carried out on a Bruker SMART APEX CCD
Preparation of [(FcCtC)2PN](F2PN)2. Following a synthetic
procedure similar to that outlined for FcCtCP3N3F5 except
with a reverse mode of addition, ethynylferrocene (2.30 g, 10.95
mmol) was reacted with N3P3F6 (1.36 g, 5.46 mmol) at -78 °C.
The compound obtained as red crystals upon elution with ethyl
acetate/hexane (2%), followed by slow evaporation, was char-
acterized as (FcCtC)2PN(F2PN)2 (3). Yield: 2.34 g (68%). Mp:
126-128 °C. IR (ν, cm-1): 2162 m (CtC), 1252 vs (PdN), 929 s
and 817 and 772 s (P-F). 1H NMR: δ 4.23 (s, 10H, CpH), 4.29
(m, 4H, -CH), 4.57 (m, 4H, -CH). 13C{1H} NMR: δ 57.57 [d,
J(C,P)=6 Hz, Cp1], 70.67 (s, Cp), 71.97 (s, Cp2/5), 72.99 (s, Cp3/4),
82.02 (s, CtC), 104.02 [d, J(C,P)=58 Hz, CtC]. 31P{1H} NMR:
˚
diffractometer with a Mo KR (λ = 0.710 73 A) sealed tube. All
crystal structures were solved by direct methods. The program
SAINT (version 6.22) was used for integration of the intensity of
reflections and scaling. The program SADABS was used for
absorption correction. The crystal structures were solved and
refined using the SHELXTL (version 6.12) package.29 All
hydrogen atoms were included in idealized positions, and a
riding model was used. Non-hydrogen atoms were refined with
anisotropic displacement parameters.
Crystallographic data and data collection parameters for
compounds 1-4 are given in Table 1, those for 5-7, 9, and 10
in Table 2, and those for 11, 13, and 14-16 in Table 3.
δ -24.83 [t, J = 86 Hz, -P(CtC-Fc)2], 6.36 (t, JP-F
=
=
Preparation of FcCtCP3N3F5. A solution of ethynylferro-
cene (0.85 g, 4.04 mmol) in 20 mL of anhydrous THF was placed
in an oven-dried, two-neck, round-bottomed flask and was
cooled to -78 °C. To this was added dropwise a solution of
n-BuLi (2.45 mL, 4.04 mmol, 1.6 M). The reaction mixture was
brought to room temperature, stirred for 3 h, and cooled again
to -78 °C. A solution of N3P3F6 (2.02 g, 8.08 mmol) in 5 mL of
THF was cooled to -78 °C, and the cooled lithiated ethynyl-
ferrocene solution was added slowly to the solution of N3P3F6.
The mixture was stirred at room temperature for 24 h. After-
ward, all solvents were evaporated off and the crude product
was purified by chromatography over silica gel. The compound
obtained as orange-red crystals upon elution with ethyl acetate/
hexane (2%), followed by slow evaporation, was characterized
as FcCtCP3N3F5 (1). Yield: 1.42 g (80%). Mp: 72-74 °C.
IR (ν, cm-1): 2180 s (CtC), 1261 vs (PdN), 946 s and 831 and
787 Hz, -PF2). 19F{1H} NMR: δ -68.10 (dm, 4F, JP-F
768 Hz, -PF2). MS (ESI) [m/e (species)]: 629.89 [M þ 1]þ. Anal.
Calcd for C24H18F4Fe2N3P3: C, 45.83; H, 2.88; N, 6.68. Found:
C, 45.87; H, 2.92; N, 6.65. E1/2 = 0.45 V vs ferrocene, reversible.
Preparation of [(FcCtC)2PN](Cl2PN)2. Following a syn-
thetic procedure similar to that outlined for [(FcCtC)2PN]-
(F2PN)2], ethynylferrocene (0.75 g, 3.57 mmol) was reacted with
N3P3Cl6 (0.61 g, 1.78 mmol) at -78 °C. Afterward, all solvents
were evaporated off and the crude product was purified through a
silica gel column. The first fraction that was obtained with hexane
was identified as unreacted ethynylferrocene (0.11 g). The com-
pound obtained as red crystals upon elution with ethyl acetate/
hexane (4%), followed by slow evaporation, was characterized as
[(FcCtC)2PN](Cl2PN)2 (4). Yield: 0.34 g (27%). Mp: 196 °C. IR
(ν, cm-1): 2163 m (CtC), 1211 vs (PdN), 581 m (PdN), 523 m
(P-Cl). 1H NMR:δ4.30 (s, 10H, CpH), 4.36 (s, 4H, -CH), 4.65 (s,
4H, -CH). 13C{1H} NMR: δ 59.21 [d, J(C, P) = 6 Hz, CtC, Cp1],
70.52 (s, Cp), 70.58 (s, Cp2/5), 72.73 (s, Cp3/4), 80.08 (s, CtC),
104.30 [d, J(C,P) = 56 Hz, CtC]. 31P{1H} NMR: δ -33.18 [t, J =
43 Hz, -P(CtC)2], 18.71 [d, J = 43 Hz, -PCl2]. Anal. Calcd for
C24H18Cl4Fe2N3P3: C, 41.49; H, 2.61; N, 6.05. Found: C, 41.61; H,
2.65; N, 6.07. E1/2 = 0.44 V vs ferrocene, reversible.
(25) Wakatsuki, Y.; Yamazaki, H. Bull. Chem. Soc. Jpn. 1985, 58, 2715–
2716.
(26) Polin, J.; Schottenberger, H. Org. Synth. 1996, 73, 262.
(27) Paddock., N. L.; Patmore, D. J. J. Chem. Soc., Dalton Trans. 1976,
1029–1031.
(28) Ritschel, J.; Sasse, F.; Maier, M. E. Eur. J. Org. Chem. 2007, 1, 78–87.
(29) SMART: Bruker Molecular Analysis Research Tools, version 5.618;
Bruker Analytical X-ray Systems: Madison, WI, 2000. (b) Sheldrick, G. M.
SAINT-NT, version 6.04; Bruker Analytical X-ray Systems: Madison, WI, 2001.
(c) Sheldrick, G. M. SHELXTL-NT, version 6.10; Bruker Analytical X-ray
Systems: Madison, WI, 2000. (d) Klaus, B. DIAMOND, version 2.1c; University
of Bonn: Bonn, Germany, 1999.
Preparation of Isomers of (η5-Cp)Co[η4-C4(N3P3F5)2(Fc)2].
Compound 1 (0.35 g, 0.79 mmol) was dissolved in 35 mL of
toluene, and CpCo(COD) (0.10 g, 0.43 mmol) in 5 mL of toluene
was added with constant stirring. The mixture was refluxed at
110 °C for 36 h. Afterward, all solvents were removed under

5764 Inorganic Chemistry, Vol. 49, No. 12, 2010
Keshav et al.
vacuum, and the resulting crude product was purified through a
silica gel column using an ethyl acetate/hexane mixture as the eluent.
The fraction that was obtained with an ethyl acetate-hexane (2%)
mixture upon evaporation yielded the compound (η5-Cp)Co[η4-C4-
1,3-(Fc)2-2,4-(N3P3F5)2] (5). Yield: 0.16 g (41%). Mp: 194-196 °C.
IR (ν, cm-1): 1268 vs (PdN), 1011 w (PdN), 942 s, 829 s (P-F). 1H
NMR: δ 4.24 (s, 10H, FeCp), 4.40 (s, 4H, -CH), 4.76 (s, 4H,
-CH), 4.93 (s, 5H, CoCp). 13C{1H} NMR: δ 69.06 (s, Cp1), 69.10
(s, Cp2/5), 69.91 (s, Cp), 74.77 (s, Cp3/4), 83.28 (s, CoCp), 85.81,
85.94 (C4 ring C). 31P{1H} NMR: δ 7.64 (tm, JP-F = 891 Hz,
-PF2), 35.48 [dm, JP-F =939 Hz, -PF(C)]. 19F{1H} NMR: δ
measured mass, 1381.8421. Anal. Calcd for C53H41CoF8Fe4N6P6:
C, 46.06; H, 2.99; N, 6.08. Found C, 46.10; H, 2.98; N, 6.04. E1/2 =
0.23 V (Fc attached to the cyclobutadiene ring), E1/2=0.43 V (-Ct
CFc) vs ferrocene, reversible. Further elution indicated the presence
of traces of two more colored species that could not be separated
and characterized.
General Procedure for the Click Reactions. The ferrocenyl-
ethynyl derivatives of cyclophosphazenes 1 and 4 were dissolved
in 25 mL of toluene, and benzyl azide was added with con-
stant stirring. The resulting reaction mixture was refluxed for
24 h. Afterward, all of the solvents were evaporated off under
vacuum, and the crude product was purified by chromato-
graphy using silica gel.
-68.99 (dm, 4F, JP-F = 880 Hz, -PF2), -65.55 (dm, 4F, JP-F
=
897 Hz, -PF2), -42.05 [d, 2F, JP-F=960 Hz, -PF(C)]. HRMS.
Calcd for C29H23CoF10Fe2N6P6: exact mass, 1001.8281; measured
mass, 1001.8271. Anal. Calcd for C29H23CoF10Fe2N6P6: C, 34.76;
H, 2.31; N, 8.39. Found C, 34.81; H, 2.29; N, 8.37. E1/2 = 0.30 and
0.42 V vs ferrocene, reversible.
Preparation of Isomers of [(FcC2N3(C6H5CH2)P3N3F5]. The
reaction between benzyl azide (0.18 g, 1.35 mmol) and (ethynyl-
ferrocenyl)pentafluorocyclotriphosphazene (1; 0.45 g, 1.02 mmol)
was carried out. Chromatography of the reaction mixture using
ethyl acetate/hexane (2%), followed by slow evaporation, gave
(1-PhCH2, 4-Fc, 5-P3N3F5)C2N3 (9) as orange-red crystals. Yield:
0.02 g (3%). Mp: 80-82 °C. IR (ν, cm-1): 1552 w (NdN), 1269 vs
(PdN), 957 m, 838 m (P-F). 1H NMR: δ 4.17 (s, 5H, CpH), 4.41
(s, 2H, -CH), 4.96 (s, 2H, -CH), 5.94 (s, 2H, -CH2), 7.01-7.04
(m, 2H, Ar-H), 7.34-7.36 (m, 3H, Ar-H). 13C{1H} NMR: δ
54.27 (s, -CH2), 69.37 [d, J(C,P)=2 Hz, Cp1], 69.72 (s, Cp2/5),
69.91 (s, Cp), 72.84 (s, Cp3/4), 126.09 (s, m-Ph), 128.50(s, p-Ph),
129.08 (s, o-Ph), 134.74 (s, ipso-Ph), 155.24, 155.55 (triazole C).
31P{1H} NMR: δ 6.63 (tm, JP-F = 928 Hz, -PF2), 20.08 [dm,
JP-F=994 Hz, -PF(C2N3)]. 19F{1H} NMR: δ -69.63 (dm, 2F,
Further elution using an ethyl acetate/hexane (4%) mixture gave
a more polar compound that was characterized as (η5-Cp)Co[η4-
C4-1,2-(Fc)2-3,4-(N3P3F5)2] (6). Yield: 0.03 g (8%). Mp: 144-
146 °C. IR (ν, cm-1): 1270 vs (PdN), 1022 m (PdN), 940 m, 828
s(P-F). 1HNMR:δ4.39 (s, 10H, FeCp), 4.50-4.60 (m, 4H, -CH),
4.84-4.94 (m, 4H, -CH), 5.08 (s, 5H, CoCp). 13C{1H} NMR: δ
68.85 (s, Cp1), 68.95 (s, Cp2/5), 69.19 (s, Cp3/4), 69.52 (s, Cp1), 69.57
(s, Cp2/5), 69.69 (s, Cp3/4), 69.84 (s, Cp), 85.16, 85.55 (C4 ring C).
31P{1H} NMR: δ 7.07 (tm, JP-F = 858 Hz, -PF2), 37.55 [dm,
J
P-F = 1002 Hz, -PF(C)]. 19F{1H} NMR: δ -69.36 (dm, 4F,
JP-F=860 Hz, -PF2), -66.78 (dm, 4F, JP-F=884 Hz, -PF2),
-42.79 [d, 2F, JP-F=967 Hz, -PF(C)]. Anal. Calcd for C29H23-
CoF10Fe2N6P6: C, 34.76; H, 2.31; N, 8.39. Found C, 34.75; H, 2.31;
N, 8.42. E1/2 = 0.26 and 0.37 V vs ferrocene, reversible.
JP-F=943 Hz, -PF2), -65.40 (dm, 2F, JP-F=906 Hz, -PF2),
-44.00 [d, 1F, JP-F = 964 Hz, -PF(C)]. MS (ESI) [m/e (species)]:
572.97 [M þ 1]þ. Anal. Calcd for C19H16F5FeN6P3: C, 39.89; H,
2.82; N, 14.69. Found: C, 39.79; H, 2.86; N, 14.74. E1/2 = 0.28 V vs
ferrocene, reversible. Upon further elution using ethyl acetate/
hexane (4%), a second fraction obtained upon slow evaporation
gave (1-PhCH2, 4-P3N3F5, 5-Fc)C2N3 (10) as orange-red crystals.
Yield: 0.24 g (41%). Mp: 142-144 °C. IR (ν, cm-1): 1551 w
(NdN), 1270 vs (PdN), 956 m, 837 m (P-F). 1H NMR: δ 4.20
(s, 5H, CpH), 4.50 (s, 2H, -CH), 4.67 (s, 2H, -CH), 6.07 (s, 2H,
-CH2), 7.16-7.18 (m, 2H, Ar-H), 7.41-7.43 (m, 3H, Ar-H).
13C{1H} NMR: δ 52.27 (s, -CH2), 67.83 (s, Cp1), 69.35 (s, Cp2/5),
69.84 (s, Cp), 70.73 (s, Cp3/4), 126.17 (s, m-Ph), 128.46 (s, p-Ph),
129.33 (s, o-Ph), 134.91 (s, ipso-Ph), 143.39, 143.89 (triazole C).
31P{1H} NMR: δ 7.20 (tm, JP-F = 899 Hz, -PF2), 24.70 [dm,
JP-F = 959 Hz, -PF(C2N3)]. 19F{1H} NMR: δ -66.78 (dm, 2F,
JP-F = 906 Hz, -PF2), -68.63 (dm, 2F, JP-F=911 Hz, -PF2),
-52.53 [d, 1F, JP-F=957 Hz, -PF(C)]. MS (ESI) [m/e (species)]:
572.92 [M þ 1]þ. Anal. Calcd for C19H16F5FeN6P3: C, 39.89; H,
2.82; N, 14.69. Found: C, 39.91; H, 2.95; N, 14.32. E1/2 = 0.46 V
vs ferrocene, reversible.
Preparation of (η5-Cp)Co[η4-C4-1,3-(Fc)2-2,4-(N3P3Cl5)2].
Following a synthetic procedure similar to that outlined for (η5-
Cp)Co[η4-C4(Fc)2(N3P3F5)2], compound 2 (0.21 g, 0.40 mmol)
was reacted with CpCo(COD) (0.05 g, 0.21 mmol) in toluene
under reflux conditions for 36 h. Afterward, all solvents were
removed under vacuum, and the resulting crude product was
purified through a silica gel column using an ethyl acetate/hexane
(4%) mixture as the eluent. The compound formed was charac-
terized as (η5-Cp)Co[η4-C4-1,3-(Fc)2-2,4-(N3P3Cl5)2] (7). Yield:
0.10 g (42%). Mp: 240 °C (dec). IR (ν, cm-1): 1269 vs (PdN), 942
m, 830 s. 1H NMR: δ 4.28 (s, 10H, FeCp), 4.40 (s, 4H, -CH), 4.87
(s, 5H, CoCp), 5.29 (s, 4H, -CH). 13C{1H} NMR: δ 69.79 (s,
Cp1), 69.93 (s, Cp), 70.42 (s, CoCp), 70.67 (s, Cp2/5),75.01(s,Cp3/4),
83.50, 85.50 (C4 ring C). 31P{1H} NMR: δ 18.89 (m, -PCl2),
27.41 [m, -PCl(C)]. Anal. Calcd for C29H23CoCl10Fe2N6P6: C,
29.86; H, 1.99; N, 7.20. Found: C, 29.84; H, 1.95; N, 7.29. E1/2
=
0.20 and 0.33 V vs ferrocene, reversible.
Preparation of (η5-Cp)Co-{η4-C4-1,3-(Fc)2-2,4-[NP(CtCFc)-
(NPF2)2]2}. Following a synthetic procedure similar to that out-
lined for (η5-Cp)Co[η4-C4(Fc)2 (N3P3F5)2], compound 3 (0.21 g,
0.33 mmol) was reacted with CpCo(COD) (0.15 g, 0.65 mmol) in
toluene under reflux conditions for 36 h. Afterward, all solvents
were removed under vacuum, and the resulting crude product was
purified through a silica gel column using an ethyl acetate/hexane
(1%) mixture as the eluent. The red fraction that was obtained
using an ethyl acetate/hexane (2%) mixture in evaporation gave a
solid that was identified as (η5-Cp)Co{η4-C4-1,3-(Fc)2-2,4-[NP-
(CtCFc)(NPF2)2]2} (8). Yield: 0.05 g (22%) Mp: 242-244 °C.
IR (ν, cm-1): 2162 m (CtC), 1253 vs (PdN), 922 m, 814 m, and
Preparation of Isomers of [(FcCtC)(FcC2N3C6H5CH2)-
PN](Cl2PN)2 and [(FcC2N3C6H5CH2)2PN](Cl2PN)2. The reac-
tion between benzyl azide (0.20 g, 1.50 mmol) and gem-ethynylferro-
cenyltetrachlorophosphazene (4; 0.42 g, 0.60 mmol) was carried out
using the general procedure given for click reactions. The first
fraction that was obtained using an ethyl acetate/hexane mixture
(1%) was evaporated to give [1-(PhCH2)-4-FcC2N3(CtCFc)PN-
(NPCl2)2] (11). Yield: 0.12 g (24%). Mp: 155-157 °C. IR (ν, cm-1):
2152 m (CtC), 1545 w (NdN), 1214 vs (PdN), 519 m (P-Cl). 1H
NMR: δ 4.23 (s, 5H, CpH), 4.30 (s, 5H, CpH), 4.41-4.42 (m, 2H,
-CH), 4.50 (m, 4H, -CH), 5.35-5.37 (m, 2H, -CH), 6.20 (s, 2H,
-CH2), 7.25-7.39 (m, 2H, Ar-H), 7.44-7.55 (m, 3H, Ar-H).
13C{1H} NMR: δ 53.80 (s, -CH2), 58.62 [d, J(C,P) = 6 Hz, Cp1],
(69.35 (s, Cp1), 69.86 (s, Cp), 70.24 (s, Cp1), 70.42 (s, Cp), 70.59 (s,
Cp2/5), 72.61 (s, Cp3/4), 80.37 (s, CtC), 106.77 [d, J(C,P) = 51 Hz,
CtC], 127.03 (s, m-Ph), 128.00 (s, p-Ph), 128.70 (s, o-Ph), 135.72 (s,
ipso-Ph), 153.54, 153.83 (triazole C). 31P{1H} NMR: δ -20.10 [t,
J=35 Hz, -P(CtC)(C2N3)], 18.32(d, J=34 Hz, -PCl2). MS(ESI)
[m/e (species)]: 826.84 [M þ 1]þ. Anal. Calcd for C31H25Cl4-
Fe2N6P3: C, 44.97; H, 3.04; N, 10.15. Found: C, 44.89, H,
1
776 w (P-F), 747 w. H NMR: δ 4.20-4.35 (m, 28H, FeCpH),
4.55-4.63 (m, 4H, -CH), 4.85 (s, 5H, -CoCp), 5.20-5.30 (m, 4H,
-CH). 13C{1H} NMR: δ 60.05 (m, CtC, Cp1), 69.40 (s, Cp1),
69.85 (s, Cp), 70.42 (s, Cp), 70.60 (s, Cp2/5), 72.57 (s, Cp3/4), 80.55
(s, CtC), 83.00 (s, CoCp), 83.79, 86.00 (C4 ring C), 104.14 [d,
J(C,P)=46.79 Hz, CtC]. 31P{1H} NMR: 0.65 [t, -PC(CtCFc)],
6.57 (t, JP-F=886 Hz, -PF2). 19F{1H} NMR: δ -69.40 (dm, 4F,
JP-F = 875 Hz, -PF2), -65.40 (dm, 4F, JP-F=903 Hz, -PF2).
HRMS. Calcd for C53H41CoF8Fe4N6P6: exact mass, 1381.8420;

Article
Inorganic Chemistry, Vol. 49, No. 12, 2010 5765
3.01, N, 10.23. E1/2=0.25 V (Fc attached to the triazole ring).
E1/2 = 0.44 V (Fc attached to the ethynyl unit) vs ferrocene,
1213 s (PdN), 517 m (P-Cl). 1H NMR: δ 4.11-4.18 (m, 14H,
CpH), 4.40-4.46 (m, 4H, CpH), 5.94 (s, 2H, -CH2), 6.81-6.91
(m, 4H, Ar-H), 7.24-7.40 (m, 6H, Ar-H). 13C{1H} NMR: δ
51.57 (s, -CH2), 68.02 (s, Cp1), 69.53 (s, Cp), 69.59 (s, Cp2/5),
70.08 (s, Cp3/4), 126.10 (s, m-Ph), 127.90 (s, p-Ph), 128.98 (s, oP-h),
135.11 (s, ipso-Ph), 142.02, 142.40 (triazole C). 31P{1H} NMR: δ
0.94 [t, J = 23 Hz, -P(C2N3)2], 19.40 (d, J = 24 Hz, -PCl2).
Anal. Calcd for C38H32Cl4Fe2N9P3: C, 47.49; H, 3.36; N, 13.12.
Found C, 47.46; H, 3.41; N, 13.05. E1/2 = 0.44 V (Fc attached to
the triazole ring), reversible.
reversible. Elution with ethyl acetate/hexane (2%) gave a second
fraction that upon evaporation gave a yellow compound that
was identified as [1-(PhCH2)-5-FcC2N3(CtCFc)PN(NPCl2)2]
(12). Yield: 0.01 g (2.0%). Mp: 162-164 °C. IR (ν, cm-1): 2161
1
m (CtC), 1549 w (NdN), 1209 vs (PdN), 517 w (P-Cl). H
NMR: δ 4.13 (s, 5H, CpH), 4.24 (s, 5H, CpH), 4.26-4.27 (m,
2H, CpH), 4.45-4.51 (m, 4H, CpH), 4.83-4.88 (m, 2H, CpH),
7.14-7.19 (m, 2H, Ar-H), 7.30-7.43 (m, 3H, Ar-H). 31P{1H}
NMR: δ -14.44 [t, J=31 Hz, -P(CtC)(C2N3)], 19.26 (d, J=31
Hz, -PCl2). HRMS. Calcd for C31H26Cl4Fe2N6P3: exact mass,
826.8885; measured mass, 826.8884. Anal. Calcd for C31H25-
Cl4Fe2N6P3: C, 44.97; H, 3.04; N, 10.15. Found: C, 44.99; H,
3.04; N, 10.11. Further elution with ethyl acetate/hexane (3%)
gave a third fraction that upon evaporation gave light-yellow
crystals that were identified as [1-(PhCH2)-4-Fc-C2N3]2PN-
(PNCl2)2 (13). Yield: 0.06 g (10%). Mp: 180 °C (dec). IR (ν,
cm-1): 1548 w (NdN), 1202 vs (PdN), 521 m (P-Cl). 1H NMR: δ
4.05-4.15 (m, 2H, CpH), 4.20-4.30 (m, 12H, CpH), 4.40-4.50
(m, 4H, CpH), 5.80 (s, 4H, -CH2), 7.05-7.15 (m, 4H, Ar-H),
7.27-7.40 (m, 6H, Ar-H). 13C{1H} NMR: δ 53.33 (s, -CH2),
64.97 (s, Cp1), 68.88 (s, Cp2/5), 69.67 (s, Cp3/4), 69.79 (s, Cp),
126.64 (s, m-Ph), 128.12 (s, p-Ph), 128.92 (s, o-Ph), 135.33 (s, ipso-
Ph), 152.87, 153.17 (triazole C). 31P{1H} NMR: δ -6.67 [t, J=28
Hz, -P(C2N3)2], 19.56 (d, J=28 Hz, -PCl2). Anal. Calcd for
C42H40Cl4Fe2N9O2P3: C, 48.08; H, 3.84; N, 12.01. Found: C,
48.01; H, 3.79; N, 12.08. E1/2=0.40 V (Fc attached to the triazole
ring), reversible. Further elution with ethyl acetate/hexane (5%)
gave a fourth fraction that upon evaporation gave yellow crystals
that were identified as [(1-PhCH2)4-Fc-C2N3)(1-PhCH25-Fc-
C2N3)PN(PNCl2)2] (14). Yield: 0.09 g (15%). Mp: 260 °C (dec).
IR (ν, cm-1): 1547 w (NdN), 1207 vs (PdN), 518 m (P-Cl). 1H
NMR: δ 4.04-4.19 (m, 16H, CpH), 4.63 (s, 2H, CpH), 5.96 (s, 2H,
-CH2), 6.10 (s, 2H, -CH2), 6.90-7.00 (m, 2H, Ar-H),
7.20-7.45 (m, 8H, Ar-H). 13C{1H} NMR: δ 51.69 (s, -CH2),
53.64 (s, -CH2), 68.69 (s, Cp1), 69.00 (s, Cp2/5), 69.50 (s, Cp),
69.70 (s, Cp1), 69.83 (s, Cp2/5), 70.12 (s, Cp3/4), 126.41 (s, m-Ph),
127.08 (s, m-Ph), 128.01 (s, p-Ph), 128.11 (s, p-Ph), 128.80 (s, o-Ph),
129.12 (s, o-Ph), 134.78 (s, ipso-Ph), 135.54 (s, ipso-Ph), 141.70,
142.14, 153.73, 154.02 (triazole C). 31P{1H} NMR: δ -1.80 [t, J =
25 Hz, -P(C2N3)2], 19.24 (d, J = 25 Hz, -PCl2). MS (ESI) [m/e
(species)]: 959.80 [Mþ 1]þ. Anal. Calcd for C38H32Cl4Fe2N9P3: C,
Preparation of trans-[(1-PhCH2-4-P3N3F5-5-Fc)C2N3]2PdCl2.
Compound 10 (0.12 g, 0.21 mmol) was dissolved in 40 mL of
toluene, and then PdCl2(PhCN)2 (0.04 g, 0.10 mmol) dissolved in
5 mL of toluene was added with constant stirring. The solution
was stirred at room temperature for 6 h. Afterward, all solvents
were removed under vacuum, and the resulting crude product was
washed twice with diethyl ether. Crystallization of the crude
reaction product in a chloroform/hexane solvent mixture yielded
orange-red crystals that were characterized as the palladium com-
plex trans-[(1-PhCH2-4-P3N3F5-5-Fc)C2N3]2PdCl2 (16). Yield:
82%. Mp: 135-137 °C. IR (ν, cm-1): 1551 m (NdN), 1274 vs
(PdN), 518 w (P-F). 1H NMR: δ 4.31 (s, 10H, CpH), 4.45-4.55
(m, 4H, -CH), 4.60-4.70 (s, 4H, -CH), 6.18 (s, 4H, -CH2),
7.35-7.50 (m, 10H, Ar-H). 13C{1H} NMR: δ 53.11 (s, -CH2),
67.26 (s, Cp1), 69.91 (s, Cp2/5), 70.06 (s, Cp), 70.93 (s, Cp3/4),
126.63 (s, m-Ph), 128.80 (s, p-Ph), 129.50 (s, oP-h), 133.41 (s, ipso-
Ph), 145.87, 146.29 (triazole C). 31P{1H} NMR: δ 7.91 (tm, J=
949 Hz, -PF2), 20.65 [dm, J= 994 Hz, -PF(C2N3)]. 19F{1H}
NMR: δ -69.52 (dm, 4F, JP-F=976 Hz, -PF2), -64.43 (dm, 4F,
J
E
P-F=965 Hz, -PF2), -48.08 [d, 2F, JP-F=948 Hz, -PF(C)].
1/2 = 0.54 V (Fc attached to the triazole ring) vs ferrocene,
reversible.
Acknowledgment. The authors thank the Department of
Science and Technology (DST), India, for financial assistance in
the form of a research grant to A.J.E. (DST (SR/S1/IC-31/
2007). We thank DST-FIST and IITD for funding of the single-
crystal X-ray diffraction facility at IIT Delhi. The authors thank
Prof. D. S. Pandey, Department of Chemistry, BHU, India, for
help in recording the electrochemical data. Thanks are due to
SAIF, CDRI, Lucknow, for providing analytical data. N.S.
thanks UGC for a senior research fellowship.
47.49; H, 3.36; N, 13.12. Found: C, 47.51; H, 3.38; N, 13.18. E1/2
=
0.23 and 0.46 V (Fc attached to the triazole ring), reversible. The
final fraction that was obtained during elution using ethyl acetate/
hexane (7%) gave a light-yellow compound that was identified
as [1-(PhCH2)-5-Fc-C2N3]2PN-(PNCl2)2 (15). Yield: 0.03 g
(5%). Mp: 204-206 °C (dec). IR (ν, cm-1): 1552 w (NdN),
Supporting Information Available: Tables of selected bond
lengths and angles of compounds 1-7, 9-11, and 13-16 and
crystallographic information files (CIF) for compounds 1-7,
9-11, and 13-16. This material is available free of charge via
the Internet at http://pubs.acs.org.