Exploring organic reactions using simple cyclodiphosphazanes

Article abstract of DOI:10.1016/j.jorganchem.2009.11.001

Phosphine-activated reactions of alkynes/alkenes/allenes as well as the Mitsunobu reaction involve a rich phosphorus chemistry. With the aid of simple cyclodiphosphazanes, characterization of many compounds analogous to the proposed intermediates in such reactions has been accomplished. Use of a cyclodiphosphazane in Pd-catalyzed N-arylation reactions is highlighted. Results on molecular non-stoichiometry in phosphorus compounds and on the use of chiral phosphorus systems are discussed. Synthesis of allenylphosphoramides involving a cyclodiphosphazane is also described. X-ray structures of the new compounds [(t-BuNH)(PhCH₂CH(CN)CH₂-)P(μ-N-t-Bu)₂P(NH-t-Bu)]⁺[HCO₃]^- (13), [(t-BuNH)P(μ-N-t-Bu)₂P({double bond, long}N-t-Bu)-C({double bond, long}CH₂)CH(C₆H₄-4-Me)-P(O)(OCH₂CMe₂CH₂O)] (18), [(i-PrNH)P(μ-N-t-Bu)₂P({double bond, long}N-i-Pr)-N(CO₂-i-Pr)-NH(CO₂-i-Pr)] (24), [(S)-(2-OH-1-C₁₀H₆-1′-C₁₀H₆-2′-O-P(O)(NH-t-Bu)₂] (36) and [(t-BuNH)(O)P(μ-N-t-Bu)₂P(O)(CH{double bond, long}C{double bond, long}CMe₂)] (40) are also reported.

Full text of DOI:10.1016/j.jorganchem.2009.11.001

Journal of Organometallic Chemistry 695 (2010) 1042–1051
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Exploring organic reactions using simple cyclodiphosphazanes q
*
K.C. Kumara Swamy , G. Gangadhararao, R. Rama Suresh, N.N. Bhuvan Kumar, Manab Chakravarty
School of Chemistry, University of Hyderabad, Hyderabad 500 046, AP, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 6 October 2009
Received in revised form 31 October 2009
Accepted 2 November 2009
Available online 10 November 2009
Phosphine-activated reactions of alkynes/alkenes/allenes as well as the Mitsunobu reaction involve a
rich phosphorus chemistry. With the aid of simple cyclodiphosphazanes, characterization of many com-
pounds analogous to the proposed intermediates in such reactions has been accomplished. Use of a
cyclodiphosphazane in Pd-catalyzed N-arylation reactions is highlighted. Results on molecular non-stoi-
chiometry in phosphorus compounds and on the use of chiral phosphorus systems are discussed.
Synthesis of allenylphosphoramides involving a cyclodiphosphazane is also described. X-ray structures
Keywords:
of the new compounds [(t-BuNH)(PhCH2CH(CN)CH2–)P(
BuNH)P( -N-t-Bu)2P(@N-t-Bu)-C(@CH2)CH(C6H4-4-Me)-P(O)(OCH2CMe2CH2O)] (18), [(i-PrNH)P(
Bu)2P(@N-i-Pr)-N(CO2-i-Pr)-NH(CO2-i-Pr)] (24), [(S)-(2-OH-1-C10H6-10-C10H6-20-O-P(O)(NH-t-Bu)2] (36)
and [(t-BuNH)(O)P( -N-t-Bu)2P(O)(CH@C@CMe2)] (40) are also reported.
Ó 2009 Elsevier B.V. All rights reserved.
l
-N-t-Bu)2P(NH-t-Bu)]+[HCO3]ꢀ (13), [(t-
-N-t-
Cyclodiphosphazane
Mitsunobu reaction
Phosphine activation
N-arylation
l
l
l
Pd-catalysis
1. Introduction
[(t-BuNH)P(
H2CMe2CH2O)] (18), [(i-PrNH)P(
NH(CO2-i-Pr)] (24), [(S)-(2-OH-1-C10H6-10-C10H6-20-O-P(O)(NH-t-
Bu)2] (36) and [(t-BuNH)(O)P( -N-t-Bu)2P(O)(CH@C@CMe2)] (40)
l
-N-t-Bu)2P(@N-t-Bu)-C(@CH2)CH(C6H4-4-Me)-P(O)(OC-
l-N-t-Bu)2P(@N-i-Pr)-N(CO2-i-Pr)-
Cyclodiphosph(III)azanes, [ClPNR]n constitute well-known
examples of inorganic ring systems [1]. Much of the chemistry
investigated earlier is on the substitution reactions involving the
P–Cl bond and on the relative geometry of the substituents on
phosphorus [1,2]. In later years, the potential of these compounds
as highly versatile ligands as well as macrocyclic precursors has
been exploited by several groups of workers [3,4]. It is to be noted
that in these compounds, both phosphorus and nitrogen are triva-
lent and hence have unshared electron pairs, but in the majority of
cases it is the one on phosphorus that takes part in the reactions.
While the ligand chemistry is fairly well-exploited, use of cyclo-
phosphazane as a nucleophile is not explored in detail. That such
a feature can be utilized effectively in exploring the mechanistic
details of traditional organic reactions is one of the objectives of
our work and is discussed in this paper. In addition, the in situ
generated metal-complexes may actually be put to use in organic
transformations is another aspect that we wish to describe herein.
In the course of our studies on cyclophosphazanes we have also
made some new observations related to molecular non-stoichiom-
etry that involves lone pair/phosphoryl bonds in cyclodiphospha-
zanes. In addition to giving a brief review of our work in this
paper, we present the X-ray structures of the new compounds [(t-
l
along with relevant details on their synthesis.
2. Results and discussion
2.1. P(III) promoted organic transformations of activated alkenes/
alkynes/allenes
As mentioned above, several organic transformations are acti-
vated in the presence of a phosphine. The primary intermediates
in these reactions are the phosphonium salts (betaines) depicted
as [(MeO2C)Cꢀ@C(CO2Me)-PR3þ] (1), [R0(O)C-C(H)ꢀC(@CH2)-PRþ3 ]
(2), [R0(O)C-C(H)@C(CH2)ꢀ-PR3þ] (3) and [(EWG)CHꢀ-CH2-PRþ3 ] (4)
EWG@CN, CO2R) in Scheme 1 [5]. It must be noted that if the phos-
phorus(III) compound bears functionalities like –NCO, –NCS or –N3,
the reaction with activated alkynes would involve these groups
also [6]. One of the most important reactions among those shown
in Scheme 1 is the Morita–Baylis–Hillman reaction [7] that leads to
a diverse number of functionalized and synthetically useful allylic
systems. Another useful reaction wherein the phosphine induces
an ‘umpolung addition’ to an alkyne system involves the formation
of a compound such as [(E)-PhCH2OCH2CH@CH(CO2Me)] (5) in
which an intermediate of type 1 is involved [5a]. Our interest in
this connection was to identify/isolate compounds analogous to
those proposed in these reactions and in this context, we have uti-
BuNH)(PhCH2CH(CN)CH2–)P(l
-N-t-Bu)2P(NH-t-Bu)]+[HCO3]ꢀ (13),
q
This work was presented at 12th International Symposium on Inorganic Ring
Systems (IRIS12) held in Goa during August 16–21, 2009.
* Corresponding author. Fax: +91 40 23012460.
lized the cyclodiphosph(III)azane [(t-BuNH)P(l-N-t-Bu)]2 (6),
E-mail addresses: kckssc@uohyd.ernet.in, kckssc@yahoo.com (K.C. Kumara
Swamy).
which is an excellent nucleophile. When this P(III) compound
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.11.001

K.C. Kumara Swamy et al. / Journal of Organometallic Chemistry 695 (2010) 1042–1051
1043
CO2Me
P
CO2Me
MeO2C
CO2Me
MeO
H
t
-Bu
(a)
+
+
MeO2C
CO2Me
(DMAD)
R3P
.
N
.
P
+
PR3
N
t
MeO2C
COR'
N
O
t
-Bu
NH-t-Bu
-Bu
t
-Bu
1
.
.
N
.
.
P
P
7
N
t
CH2
+
-Bu
NHt
-Bu
H
t
-BuNH
H
COR'
(b) R3P
t
-Bu
+
6
+
P
COR'
EWG
N
.
PR3
PR3
.
MeO2C
CO2Me
P
2
3
N
t
NH-t-Bu
-Bu
t
-BuNH
H
EWG
H
EWG = CN, CO2R
t
-Bu
(c)
+
+
R3P
.
N
R3P
.
4
MeO2C
P
P
(Morita-Baylis-Hillman intermediate)
N
t
N
NH-t-Bu
-Bu
t
-Bu
Example
8
H
H
C
C
C
Scheme 2.
PhCH2O
H
CO2Me
CO2Me
PhCH2OH
or
Ph3P (5 mol%)
HOAc (20 mol%)
CO2Me
H3C
5
EWG
R'
EWG
Scheme 1.
+
PPh3
+
PR3
[Nu
]
[Nu ]
R'
was treated with dimethylacetylene dicarboxylate (DMAD), in-
stead of the expected phosphonium salt or any of its tautomeric
form, we obtained the novel five-membered ring heterocycle
9
10
R' = Alkyl, CO2Me etc.
EWG = CN, CO2R, C(O)Me
Nu = oximato
EWG = CO2R, C(O)R etc.
Nu = -OAr, -OR, thiobenzamidato etc.
(t-Bu-NH)P(
however, use of methyl propiolate afforded the tautomeric form
(t-Bu-NH)P( -N-t-Bu)2P(@N-t-Bu)[CH@CH(CO2Me)] (8) of the ex-
l-N-t-Bu)2P{@C(CO2Me)-CH(OMe)-C(O)-N-t-Bu} (7),
NC
Ph-OH
(slight excess)
t-Bu
N
l
CH2 CH2
N
.
.
pected phosphonium salt [8]. Despite the fact that 7 or 8 is not a
phosphonium salt, the formation of P–C bond vindicates the
involvement of the postulated intermediates shown in Scheme 1.
P
P
6 +
CH2=CHCN
toluene, 6 h
N
t-Bu
NH-t-Bu
t-Bu
11
NC
_
t-Bu
N
CH2 CH2
.
P
+
P
.
Ph O
HO Ph
N
t-Bu
HN
t-Bu
NH-t-Bu
In the reactions shown in Scheme 1, the first stage intermediates so
formed undergo reactions with nucleophiles ArOH/ROH to lead to
the phosphonium salts of types [(EWG)CH@C(R0)(PR3)]+[Nu]ꢀ (9)
and [(EWG)CH2CH(R0)(PPh3)]+[Nu]ꢀ (10) [EWG@electron with-
drawing group] prior to the formation of the required products
[9]. We have observed that it is indeed possible to isolate such
12 [δ(P) = 3.6, 75.7, 65%; X-ray]
Scheme 3.
Bu)2P(NH-t-Bu)]+[HCO3]ꢀ (14) [d(P) 21.1, 83.4]. The P(1)–N(3) dis-
tance of 1.607(3)Å in 13 is longer than that reported for 11
[1.526(2) Å] [8] as expected for the P–N single bond in 13 and dou-
ble bond in 11.
products {e.g. [(t-BuNH)((CN)CH2CH2-)P(l
-N-t-Bu)2P(NH-t-Bu)]+-
[PhOHꢁꢁꢁOPh]ꢀ (12)} (Scheme 3) as shown by the isolation of (t-
Bu-NH)P(l-N-t-Bu)2P(=N-t-Bu)(CH2CH2CN) (11) (see Scheme 2).
In contrast to the above, the reaction of [(t-BuNH)P(
l
-N-t-Bu)]2
We have also explored the reaction of allenylphosphonates with
(6) with PhCH2C(CN)@CH2 is slightly different. Although at room
temperature there was no reaction, when the mixture was refluxed
in toluene for 2 d, the signal for 6 disappeared in the 31P NMR spec-
trum and the reaction mixture showed mainly four peaks [ꢀ17.6
and ꢀ7.1 (tetracoordinate) 72.1 and 74.1 (tricoordinate)] (Fig. 1).
These peaks are most likely due to two isomeric species that differ
about the P@N bond (or two tautomeric forms). Upon attempted
purification through silica gel column, only the new ionic compound
the cyclodiphosphazane [(t-BuNH)P(
we could isolate both the enantiomers of the product
[(t-Bu-NH)P( -N-t-Bu)2P(@N-t-Bu)C(@CH2)-CH(Ph)-P(O)(OCH2
CMe2CH2O)] (16) from the reaction of 6 with the allene (OCH2
CMe2CH2O)P(O)C(Ph)@C@CH2 (15) [10]. The identity of the two
enantiomers (separated by spontaneous resolution) has been con-
firmed by X-ray crystallography as well as CD spectra of the crys-
tals. In the present work, the reaction of the p-tolyl substituted
allene (OCH2CMe2CH2O)P(O)C(C6H4-4-Me)@C@CH2 (17) was per-
l-N-t-Bu)]2 (6). Interestingly,
l
[(t-BuNH)(PhCH2CH(CN)CH2-)P(l
-N-t-Bu)2P(NH-t-Bu)]+[HCO3]ꢀ
(13) was isolated (Scheme 4). The anion, analyzed as [HCO3]ꢀ by X-
ray crystallography (Fig. 2), could have come from the absorption of
adventitious carbon dioxide-moisture. In a similar way, compound
formed. We did obtain the expected new product [(t-BuNH)P(l-N-
t-Bu)2P(@N-t-Bu)-C(@CH2)CH(C6H4-4-Me)-P(O)(OCH2CMe2CH2O)]
(18), but it crystallized as a racemic mixture (Fig. 3). Nevertheless,
the results clearly show that the initial attack of the P(III) species
(in this case compound 6) occurs at the central carbon of the allene
part giving a reasonable proof for the proposed intermediate of the
(t-Bu-NH)P(
71.6], prepared as described above, on passing through silica gel
column gave the ionic product [(t-BuNH)((CN)CH2CH2-)P( -N-t-
l
-N-t-Bu)2P(@N-t-Bu)(CH2CH2CN) (11) [d(P) ꢀ12.9,
l

1044
K.C. Kumara Swamy et al. / Journal of Organometallic Chemistry 695 (2010) 1042–1051
Fig. 2. Molecular structure of 13. Selected bond distances (Å): P(1)–N(1) 1.633(3),
P(1)–N(2) 1.639(3), P(1)–N(3) 1.607(3), P(1)–C(17) 1.792(4), P(2)–N(1) 1.756(3),
P(2)–N(2) 1.763(3), P(2)–N(4) 1.641(4). Bicarbonate proton was not located.
Hydrogen bond parameters: N(3)–H(4N)ꢁꢁꢁO(1) 0.88(4), 2.00(4), 2.870(5) Å,
171(4)°; N(4)–H(3N)ꢁꢁꢁO(1) 0.87(4), 2.19(5), 3.042(5) Å, 166(4)°.
detailed characterization of these or analogous species had eluded
detection prior to our work [11]. By making use of the cyclodi-
Fig. 1. The 31P NMR spectra of (a) pure compound 11, (b) reaction mixture of
compound 6 + (PhCH2)(CN)C@CH2 containing (A) and (c) pure compound 13.
type [(R0(O)C)-C(H)ꢀC(@CH2)-PR3þ] (2) or [R0(O)C-C(H)@C(CHꢀ2 )-
PRþ3 ] (3) shown in Scheme 1 (see Scheme 5).
2.2. Reaction of compound [(t-BuNH)P(l-N-t-Bu)]2 (6) and related
cyclodiphosphazanes with dialkyl azodicarboxylates-implications for
the mechanism of Mitsunobu reaction
The redox combination of a phosphine and a dialkyl azodicar-
boxylate is the key to the success of the well-known Mitsunobu
reaction in which esterification of an acid (and related reactions)
with inversion of configuration for asymmetric alcohols can be
accomplished under very mild conditions [5b]. Several phosphorus
based intermediates like [Ph3P+-N(CO2R)-Nꢀ-CO2R] (19), [Ph3P-
N(CO2R)-NH-CO2R]+[R0CO2]ꢀ (20) and [Ph3P(OR00)]+[R0CO2]ꢀ (21)
have been proposed in this synthetically useful reaction. However,
Fig. 3. Molecular structure of 18. Selected bond distances (Å): P(1)–N(1) 1.683(2),
P(1)–N(2) 1.680(2), P(1)–N(3) 1.540(2), P(1)–C(17) 1.828(3), P(2)–N(1) 1.735(2),
P(2)–N(2) 1.743(2), P(2)–N(4) 1.660(3).
NC
CN
PhCH2
t-Bu
N
t-Bu
CH CH2
.
.
.
.
N
.
.
P
PhCH2
P
P
P
N
t-Bu
N
t-Bu
(A)
NH-t-Bu
t-Bu-HN
N
t-Bu
NH-t-Bu
Toluene
reflux
6
δ(P): -17.6, -7.1, 72.1, 74.1
(Similarly prepared from 11)
NC
t-Bu
NC
CH CH2
+
P
N
.
.
t-Bu
N
H
CH CH2
P
Silica gel
(+CO2 +H2O)
+
P
.
.
N
t-Bu
PhCH2
P
HN
t-Bu
NH-t-Bu
HCO3
N
t-Bu
HN
t-Bu
NH-t-Bu
HCO3
13 [δP: (major peaks) 21.4, 88.0; X-ray]
14 [δ(P): 21.1, 83.4, 90%]
Isolated yield 10%
Scheme 4.

K.C. Kumara Swamy et al. / Journal of Organometallic Chemistry 695 (2010) 1042–1051
1045
O
O
H
O
H
P
H
H
O
O
O
C
C
C
t-Bu
N
P
α
γ
β
*
.
.
Ph
P
P
15
N
t-Bu
Ph
N
NH-t-Bu
toluene
1d, rt
t-Bu
16, δ(P): -19.4, 20.4, 70.5, 90%; X-ray
both the enantiomers by crystallization
(spontaneous resolution)
t-Bu
N
O
.
O
.
.
.
P
P
P
H
H
N
t-Bu
O
C
C
β
C
NH-t-Bu
t-Bu-HN
H
O
H
α
γ
6
O
O
t-Bu
N
P
Me
.
17
.
P
P
N
t-Bu
toluene
1d, rt
N
NH-t-Bu
t-Bu
Me
18, δ(P): -18.8, 20.8, 71.3, 92%; X-ray
Scheme 5.
phosphazane [(t-BuNH)P(
characterize several compounds, which include [(t-BuNH)P(
l
-N-t-Bu)]2 (6), we have been able to
the corresponding oxidized species of type [(R2N(O)P-N-t-Bu]2 as
isolatable products. Another important point in these systems is
the 31P NMR chemical shift of the phosphinimine part. While in
23 this value is -28.9 ppm, in the morpholino compound [(cycl-
l
-N-
t-Bu)2P(@N-t-Bu)-N(CO2R)-NH(CO2R] [R = Et (22), i-Pr (23)]
(Scheme 6). It may be noted that 22–23 are the tautomeric forms
of the expected betaine analogous to [Ph3P+-N(CO2R)-Nꢀ-CO2R]
(19); thus a reasonable (though not exact) evidence for the pro-
posed first stage intermediate in the Mitsunobu reaction is pro-
vided from our work. The question as to whether the t-BuNH
group on the cyclophosphazane is really required or not is an-
OC4H8N)P(
prepared similarly [11c] it is ꢀ51.5, which is well inside the penta-
coordinate region Fig. 5; cf. (cycl-OC4H8N)P( -N-t-Bu)2P(NH-t-
l-N-t-Bu)2P(@N-t-Bu)-N(CO2-i-Pr)-NH(CO2-i-Pr)] (25)
l
Bu)(N(CO2-i-Pr)-N@C(O-i-Pr)O-) (2500) and hence it is likely that
in solution, there is a significant contribution from this form [12].
This observation also suggests that the nature of the species in
the reaction of P(III) compounds with DIAD/DEAD depends on
the substituents present on the phosphorus that include the beta-
ine, imine (where proton shift is possible) and pentacoordinate
swered by isolating the i-PrNH analogue [(i-PrNH)P(l-N-t-
Bu)2P(@N-i-Pr)-N(CO2-i-Pr)-NH(CO2-i-Pr)] (24) which is a new
compound (Fig. 4). This result indicates that the availability of a
proton on N is necessary for the success of this reaction. However,
it is important to note that in aminophosphites with an –NH-i-Pr
group, a pentacoordinate derivative was obtained [12]. We have
also attempted to use other secondary amino groups like morpho-
lino or dimethylamino, but in these cases the reaction led only to
phosphorane ꢀ [cf. 25, (cycl-OC4H8N)P(
l
-N-t-Bu)2P+(NH-t-Bu)-
N(CO2-i-Pr)-N (CO2-i-Pr) (250) and 2500]. This point is also of some
relevance since it is known that similar pentacoordinate deriva-
tives take part in the Mitsunobu esterification [13].
O
C
O
C
O
C
O
+
-
-
H
N
RO
N
N
OR
Ph3P
[R'COO]
[R'COO]
OR"
RO
N
C
OR
+
+
PPh3
PPh3
21
19
20
C(O)OR
OR
C(O)
N
RO(O)C
t-Bu
N
t-Bu
N
N
N
.
.
+
P
.
.
.
.
N
P
P
+
P
N
N
NH-t-Bu
t-Bu
NHt-Bu
C
t-Bu
t-BuNH
t-BuNH
OR
O
6
C(O)O-i-Pr
i-PrO(O)C
H
C(O)OR
RO(O)C
t-Bu
N
t-Bu
N
N
N
N
N
.
.
.
.
P
P
P
P
H
N
N
N
NH-i-Pr
t-Bu
NH-t-Bu
N
t-Bu
i-Pr
t-Bu
24: δ(P) -6.8, 73.3; X-ray
R = Et [22: δ(P) -28.7, 68.9]
i-Pr [23: δ(P) -28.9, 68.9; X-ray]
Scheme 6.

1046
K.C. Kumara Swamy et al. / Journal of Organometallic Chemistry 695 (2010) 1042–1051
Fig. 4. Molecular structure of 24. Selected bond distances (Å): P(1)–N(1) 1.744(3),
P(1)–N(2) 1.768(2), P(1)–N(3) 1.655(2), P(2)–N(1) 1.647(3), P(2)–N(2) 1.649(4),
P(2)–N(4) 1.531(4), P(2)–N(5) 1.727(4). Hydrogen bond parameters (intermolecu-
lar): N(3)–H(3N)ꢁꢁꢁO(3) 0.72(5), 2.35(5), 3.067(5) Å, 170(5)°. Symmetry code:
ꢀx + 1/2, y ꢀ 1/2, ꢀz + 1/2.
CO2-i-Pr
CO2-i-Pr
NCO2-i-Pr
t
-Bu
t
-Bu
N
NCO2-i-Pr
N
N
+
P
.
N
.
.
.
H
P
P
P
N
N
N
NH-t-Bu
N
N-t-Bu
t
-Bu
t
-Bu
O
N
O
25'
25 [δ(P) 69.7, -51.5; X-ray]
i-PrO2C
N
t
-Bu
N
N
.
.
O-i-Pr
P
P
O
N
t
-Bu
NH-t-Bu
O
25''
Fig. 5. The 31P NMR spectra of 23 (bottom) and 25, illustrating the significant
difference in the chemical shift at the phosphinimine region.
As shown in Scheme 1, at the second stage of the Mitsunobu reac-
tion, species of type [Ph3P-N(CO2R)-NH-CO2R]+[R0CO2]ꢀ (20) are
the proposed intermediates. Here we had better success and could
isolate compounds [(t-BuNH)P(l-N-t-Bu)2P(NH-t-Bu)-N(CO2-i-Pr)-
survey of X-ray structures for several other P(III) and their corre-
sponding P(V) compounds revealed that the difference in cell vol-
ume due to the extra oxygen per molecule in the crystals is only
about 6 Å3. Thus in the crystallization process of sufficiently large
molecules, it can be expected that a compound with the phos-
phoryl group (P@O) may co-crystallize with the corresponding
P(III) derivative to form solid solutions. The individual compounds
will be intact, but can interchangeably pack in the crystal lattice,
NH(CO2-i-Pr]+[RCO2]ꢀ [R = Ph (26), 4-Cl-C6H4CH2 (27), 4-Br-C6H4
(28), and 4-O2N-C6H4 (29) by the addition of carboxylic acids to
(t-BuNH)P(l-N-t-Bu)2P(@N-t-Bu)-N(CO2-i-Pr)-NH(CO2-i-Pr) (23)
[11c]. Interestingly, these compounds undergo the Mitsunobu
esterification and thus lend credence to the postulated intermedi-
ates like 20 [11c] (see Scheme 7).
2.3. Molecularly non-stoichiometric crystals of cyclodiphosphazane
derivatives
CO2-i-Pr
CO2-i-Pr
Between the two most prevalent oxidation states for phospho-
rus, three and five, a significant number of compounds in the latter
oxidation state can be simply prepared by treating P(III) com-
pounds with suitable oxidizing agents, to lead to compounds with
a phosphoryl bond. This part of our work was originally intended
for the synthesis of chiral phosphoramidates based on a cyclodi-
phosphazane system for use in asymmetric synthesis such as
reduction [14]. However, while synthesizing the required bina-
phthoxy-substituted cyclophosphazanes, we found that the P(III)
precursor and its oxidized products had similar cell parameters,
as shown by X-ray structure determination. A Cambridge database
t-Bu
N
N
N
N
.
+
RC(O)OH
.
P
P
H
23
O
C
N
t-BuNH
t-Bu
_
H
O
t-Bu
R
R = Ph
[26: δ(P) 1.1, 81.0 (X-ray)]
[27: δ(P) 0.1 (br), 80.4 (br)]
4-Cl-C6H4CH2
4-Br-C6H4
4-NO2-C6H4
[28: δ(P) 2.1, 81.5]
[29: δ(P) 2.9, 82.0]
Scheme 7.

K.C. Kumara Swamy et al. / Journal of Organometallic Chemistry 695 (2010) 1042–1051
1047
O
.
HO
H
Cl
.
.
HO
H
.
32
P
P
P
P
2 NEt3
O
OH
OH
Me
+ BH3.SMe2
+
Me
Me
+
t-Bu
t-Bu
N
Nt-Bu
t-Bu
N
N
-2 NEt3HCl
O
.
.
.
.
Yield > 90%
ee 5-8%
Cl
31 [δ(P): 171.2]
binapthol
30 [δ(P): 207.9]
S (-)
t-Bu
H
OH
N
O
t-Bu
O
O
P
N
P
P
H
m-CPBA
O
O
O
t-Bu
N
Nt-Bu
t-Bu
N
N
t-Bu
36 [see text; δ(P): 6.2 (X-ray)]
O
O
P
P
.
.
O
33 [δ(P): 98.5 (d), 4.4 (d); 2J = 12.8 Hz]
Scheme 9.
32 [δ(P): -7.8]
Scheme 8.
thus leading to crystals which can be termed as molecularly non-
stoichiometric. Although the concept looks simple, this aspect
had not been investigated prior to our work. The importance of this
observation can be appreciated when we realize that obtaining sin-
gle crystals does not guarantee the purity of the compound. The
first system in cyclodiphosphazanes that we encountered is shown
in Scheme 8. Compounds (S)-(O-C10H6-C10H6-O-)[P(
l-N-t-Bu)2P]
(31) and (S)-(O-C10H6-C10H6-O-)[(O)P( -N-t-Bu)2P(O)] (32) crystal-
l
lize in the same space group P212121 with very similar unit cell
dimensions; upon mixing, they form the co-crystal readily in the
ratio 1:2.3 as evidenced by X-ray crystallography and 31P NMR
spectra for the crystals after dissolution in CDCl3 [15]. This obser-
vation was useful in explaining the difficulty in obtaining pure
mono-oxidized compound (S)-(1,10-O-C10H6-C10H6-O-)[(O)P(
l-N-
t-Bu)2P] (33); the crystals of this compound also belonged to the
same space group with (again) similar unit cell dimensions and
contained ca 5% of the fully oxidized product 32. More dramatic
is the system represented by compounds [(2,6-Me2C6H3O)(O)P(
l-
N-t-Bu)]2 (34) and (2,6-Me2C6H3O)(O)P( -N-t-Bu)2P(O-2,6-
l
Fig. 6. An ORTEP drawing of compound 36. Selected bond distances (Å): P–O(1)
1.601 (2), P–O(2) 1.472 (2), P–N(1) 1.615(3), P–N(2) 1.620(3). H-bond parameters
O(3)–H(1)ꢁꢁꢁO(2) 0.77(5) Å, 1.88(5) Å, 2.614(3) Å, 160(5)°. Symmetry code: 1 ꢀ x,
0.5 + y, 0.5 ꢀ z.
Me2C6H3) (35) [15b]. Here, three different types of crystals with
varying stoichiometry of 34 and 35 are obtained (cf. the structural
drawings). The results are proven by the combined use of 31P NMR
spectroscopy and X-ray crystallography. Thus it is imperative that
in synthesis involving oxidation of P(III) systems, we should be
careful not to assume that the crystals are necessarily pure com-
pounds.
2.4. The cyclodiphosphazane [ClP(l-N-t-Bu)]2 (30) as a co-ligand for
the palladium catalyzed amination of aryl bromides and chlorides
C–N Bond formation by palladium catalyzed cross coupling
reaction is one of the powerful techniques in synthetic organic
chemistry. To the best of our knowledge, only two reports have ap-
peared describing the utility of chloro(amino)phosphines as
ligands in this type of coupling [16]. In this context, we felt that
t-Bu
N
t-Bu
N
O
O
O
.
.
P
P
+
P
P
N
t-Bu
N
t-Bu
O
O
O
O
Ar
Ar
Ar
Ar
cyclodiphosphazane derivative [ClP(l-N-t-Bu)]2 (30) bearing a
34 [δ(P): -6.0]
35 [δ(P): 2.1, 106.3; J = 11.5 Hz]
bulky t-butylamino substituent as a ligand should be quite useful.
Thus we have been fairly successful in using 30 and three examples
from our recent work are presented in Scheme 10 [17]. Using this
route, we have been able to effect N-arylation of aniline using the
bulky aryl bromide, 1-bromo-2,4,6-trimethylbenzene, albeit in
somewhat lower yields (38%). Currently, we are trying to extend
the use of cyclodiphosphazanes to other reactions that include
the Suzuki coupling.
34 (%): 35 (%)
Me
10: 90
40: 60
70: 30
Ar
100: 00
Me
As regards our original objective of using (S)-(O-C10H6-C10H6-O-)
[(O)P( -N-t-Bu)2P(O)] (32) for chiral catalysis, we have tried the
l
reduction of acetophenone (Scheme 9). The chiral induction was
low, but in addition, we noted that the phosphoramidate 32 was
not particularly stable under these conditions. We were able to iso-
late the new ring-cleaved product [(S)-(2-OH-1-C10H6-10-C10H6-20-
O-P(O)(NH-t-Bu)2] (36) (Fig. 6). It is thus possible that even in the
reactions reported in the literature [14] the true catalyst may not
be the original N–P@O compound.
2.5. Allenes derived from cyclodiphosphazanes
Allenes have two cumulative orthogonal double bonds and are
versatile intermediates in organic chemistry. The P–Cl bond in
[ClP(l-N-t-Bu)]2 (30) can be readily converted to allenylphosph-
oramidates by treating it with suitable propargylic alcohols. This
has been shown by us recently and the compounds

1048
K.C. Kumara Swamy et al. / Journal of Organometallic Chemistry 695 (2010) 1042–1051
Pd2(dba)3 (3 mol%)
[ClPN-t-Bu]2 (30)
NaO-t-Bu (1.4 mmol)
two cases. In addition to these, the new partially oxidized allenyl
product [(t-BuNH)(O)P( -N-t-Bu)2P(O)(CH@C@CMe2)] (40)
t-Bu
N
l
.
.
.
.
P
P
(Fig. 7) was obtained in traces. Although we are yet to ascertain
the details of its formation, its isolation could open up further
opportunities for exploration. Finally, we believe that compounds
37–39 have the potential to be used as polymer precursors, but this
work still needs to be done (see Scheme 11).
N
t-Bu
30
O
N
Ar
O
Ar-X
NH
+
Cl
Cl
Toluene, reflux, 24 h
(oil bath: 120 oC)
68-75% (isolated)
Ar-X =
Cl
CF3
CF3
Me
Cl
OMe
etc.
Br
N(H)t-Bu
O
t-Bu
N
O
Me
Me
P
P
N
t-Bu
Scheme 10.
H
40
3. Conclusion
By means of five different systems, we have shown the syn-
thetic potential of simple cyclodiphosphazanes. These involve the
use of (i) [(t-BuNH)PN-t-Bu]2 as a mechanistic probe for the Mits-
unobu and phosphine catalyzed reactions of alkenes/alkynes/al-
lenes (ii) generation of molecularly non-stoichiometric crystals
via derivatives of [ClP-l-N-t-Bu]2, (iii) Pd(0) catalyzed N-arylation
reactions mediated by [ClP-
l
-N-t-Bu]2 and (iv) syntheses of new
allenylphosphoramides. We believe that further exploration, in
particular in homogeneous catalysis, will bear more fruits in the
coming years.
4. Experimental
General experimental conditions are available in a recent paper
[19]. Compounds [(t-BuNH)P(
l-N-t-Bu)]2 (6) [8,11c], (t-Bu-
Fig. 7. Molecular structure of 40. The other set of positions for t-butyl atoms
connected to C1 are omitted for clarity. Selected bond distances (Å): P(1)–N(1)
1.667(2), P(1)–N(2) 1.662(2), P(1)–O(1) 1.463(2), P(1)–C(13) 1.782(2), P(2)–N(1)
1.676(2), P(2)–N(2) 1.703(2), P(2)–N(3) 1.616(2), P(2)–O(2) 1.462(2). Hydrogen
bond parameters (intermolecular): N(3)–H(3D)ꢁꢁꢁO(1) 0.75(2), 2.28(2), 3.014(3) Å,
164(3)°. Symmetry code: 1 ꢀ x, 2 ꢀ y, ꢀz.
NH)P( -N-t-Bu)2P{@C(CO2Me)-CH(OMe)-C(O)-N-t-Bu} (7) [8,11c],
l
(t-Bu-HN)P(
l
-N-t-Bu)2P(@N-t-Bu)[CH@CH(CO2Me)] (8) [8,11c],
-N-t-Bu)2P(@N-t-Bu)(CH2CH2CN) (11) [8], [(t-
(t-Bu-NH)P(
l
BuNH)((CN)CH2CH2-)P(
[8], (OCH2CMe2CH2O)P(O)C(Ph)@C@CH2 (15) [10], [(t-Bu-HN)P(l-
l
-N-t-Bu)2P(NH-t-Bu)]+[PhOHꢁꢁꢁOPh]ꢀ (12)
N-t-Bu)2P(@N-t-Bu)C(@CH2)-CH(Ph)-P(O)(OCH2CMe2CH2O)] (16)
[10], (OCH2CMe2CH2O)P(O)C(C6H4-4-Me)@C@CH2 (17) [20], [(t-
[(RR0C@C@CH)(O)P( -N-t-Bu)2P(O)(CH@C@CRR0)] [R = R0 = H (37),
l
BuNH)P(l-N-t-Bu)2P(@N-t-Bu)-N(CO2R)-NH(CO2R] [R = Et (22),
R = R0 = Me (38), R = Me, R0 = Et (39)] have been prepared and struc-
turally characterized [18]. It can be readily noted that both cis- and
trans- isomers are possible and both of these have been isolated in
i-Pr (23)] [11c], [(cycl-OC4H8N)P(
l-N-t-Bu)2P(@N-t-Bu)-N(CO2-i-
Pr)-NH(CO2-i-Pr)] (25) [11b], [(t-BuNH)P(l-N-t-Bu)2P(NH-t-Bu)-
N(CO2-i-Pr)-NH(CO2-i-Pr]+[RCO2]ꢀ [R = Ph (26), 4-Cl-C6H4CH2
t-Bu
t-Bu
R
.
P
N
.
Et3N
.
.
.
P
N
.
.
P
.
H
C
C
R'
OH
+
P
N
t-Bu
R
N
t-Bu
-Et3N.HCl
O
O
Cl
Cl
R
C
30
C
R'
R'
C
C
H
H
Δ
H
R
t-Bu
N
H
O
R
H
R
t-Bu
R'
R
+
P
P
N
N
t-Bu
R'
R'
P
P
O
N
R'
H
O
O
t-Bu
cis
[37, δ(P): 2.5, 75%; X-ray]
[38a, δ(P): 4.8, 60%; X-ray]
R = Me; R' = Et [39a, δ(P): 4.6, 40%]
trans
R = R' = H
R = R' = Me
R = R' = Me [38b, δ(P): 9.2, 15%; X-ray]
R = Me; R' = Et [39b, δ(P): 9.0, 15%]
Scheme 11.

K.C. Kumara Swamy et al. / Journal of Organometallic Chemistry 695 (2010) 1042–1051
1049
(27), 4-Br-C6H4 (28), and 4-O2N-C6H4 (29) [11b,c], [ClP(
(30) [18], (S)-(1,10-O-C10H6-C10H6-O-)[P(
-N-t-Bu)2P] (31) [15a],
(S)-(1,10-O-C10H6-C10H6-O-)[(O)P(
-N-t-Bu)2P(O)] (32) [15a], (S)-
(1,10-O-C10H6-C10H6-O-)[(O)P(
-N-t-Bu)2P] (33) [15a], [(2,6-Me2-
C6H3O)(O)P( -N-t-Bu)]2 (34) [15b], (2,6-Me2C6H3O)(O)P(
l
-N-t-Bu)]2
P(O)C(C6H4-4-Me)@C@CH2 (17) [20] (0.386 g, 1.38 mmol) were
dissolved in dry toluene (8 mL), and the mixture was stirred at
room temperature for 1 d. The solution was concentrated in vacuo
(to ca 3 mL) and cooled for 1 d at ꢀ4 °C to obtain crystals of [(t-
l
l
l
l
l-N-t-
-N-t-
BuNH)P(l-N-t-Bu)2P(@N-t-Bu)-C(@CH2)CH(C6H4-4-Me)-P(O)(OCH2C-
Bu]2P(O-2,6-Me2C6H3) (35) [15b], and [(RR0C@C@H)(O)P(
l
Me2CH2O)] (18). Yield: 0.804 g (92%). M.p.: 178–180 °C. IR (KBr): 3335,
Bu)2P(O)(CH@C@CRR0)] [R = R0 = H (37), R = R0 = Me (38), R = Me,
2970, 2901, 2629, 2550, 2262, 1819, 1606, 1512, 1473, 1361, 1280,
R0 = Et (39)] 37–39 [18] have been reported before. Compound
1215, 1062 cmꢀ1 1H NMR (400 MHz, CDCl3): d 0.89, 1.17, 1.27,
.
[(t-BuNH)(O)P(
l
-N-t-Bu)2P(O)(CH@C
@CMe2)]
(40)
(CCDC
1.39 and 1.40 (5s, 42H, C(CH3)2 + C(CH3)3), 2.28 (1s, 3H, Ar–CH3),
2.67 (d, 2J(P–H) = 8.0 Hz, 1H, NH), 3.80–4.35 (m, 4H, OCH2), 5.75
(dd, 3J(P–H) ꢂ 26.8 Hz, 4J(P–H) = 3.6 Hz, 1H,@CHAHB, cis to P),
6.01 (dd, 3J(P–H) ꢂ 11.6 Hz, 2J(P–H) ꢂ 14.8 Hz, 1H, P(O)CH), 6.79
(d, 3J(P–H) ꢂ 51.6 Hz, 1H, = CHAHB, trans to P), 7.04 (d, 3J(H–H) =
8.0 Hz, 2H, Ar–H), 7.42 (d, 3J(H–H) = 7.6 Hz, 2H, Ar–H). 13C NMR
(100 MHz, CDCl3): d 20.91 and 21.07 (2s, C(CH3)2), 21.96 (Ar–
CH3), 31.07 (d, 3J(P–C) = 24.3 Hz, C(CH3)3), 32.38 (d, 3J(P–C) =
6.3 Hz, C(CH3)3), 32.87 (d, 3J(P–C) ꢂ 9.6 Hz, C(CH3)3), 34.54 (d,
3J(P–C) = 12.0 Hz, C(CH3)3), 41.09 (dd, 1J(P–C) ꢂ 125.0 Hz, 2J(P–C)
= 4.6 Hz, P(O)C(Ar)), 51.37 (d, 2J(P–C) = 14.6 Hz, C(CH3)3), 52.22
(dd ? t, 2J(P–C) ꢂ 9.5 Hz, C(CH3)3), 52.55 (d, 2J(P–C) = 8.1 Hz,
C(CH3)3), 76.46 and 76.52 (2s, OCH2), 128.21, 128.86, 129.01,
129.97, 133.04 (d, 2J(P–C) ꢂ 7.4 Hz) and 136.53 (Ar–C + PC@CH2),
143.47 (d, 1J(P–C) = 163.0 Hz, PC@CH2). 31P NMR (160 MHz, CDCl3):
d ꢀ18.71 (dd, 2J(P–P) ꢂ 6.4 Hz, 3J(P–P) ꢂ 35.2 Hz), 20.86 (d, 3J(P–P)
ꢂ 35.2 Hz), 71.30 (d, 2J(P–P) ꢂ 6.4 Hz). LC–MS: m/z 627 [M+1]+.
CCDC number 749652.
749655) was obtained in very small quantities along with 38a,b,
probably as an impurity from the starting material 30; this aspect
is still under study. The procedure for the N-arylation of 1-bromo-
2,4,6-trimethylbenzene was similar to that reported by us recently
[17]. Details on the other new compounds are presented below.
4.1. Synthesis of compounds [(t-BuNH)(PhCH2CH(CN)CH2-)
P(
P(
l
l
-N-t-Bu)2P(NH-t-Bu)]+[HCO3]ꢀ (13) and [(t-BuNH)((CN)CH2CH2-)
-N-t-Bu)2P(NH-t-Bu)]+[HCO3]ꢀ (14)
To a solution of [(t-BuNH)P(l-N-t-Bu)]2 (6) (0.706 g, 2.02 mmol)
in toluene (10 mL), 2-benzyl-acrylonitrile (0.433 g, 3.03 mmol) was
added via syringe at room temperature and mixture heated under
reflux for 2 d. At this stage, the 31P NMR spectrum showed mainly
four peaks [ꢀ17.6 and ꢀ7.1 (tetracoordinate) 72.1 and 74.1 (trico-
ordinate)] corresponding to two species. This solution was concen-
trated in vacuo and chromatographed (silica gel, 85% ethyl acetate
–
15% hexane) to get [(t-BuNH)(PhCH2CH(CN)CH2-)P(l-N-t-
Bu)2P(NH-t-Bu)]+[HCO3]ꢀ (13). The product eluted from column
was different from that present before. The silica gel was tested
for the presence of nitrate after washing with water several times,
but no detectable amount of nitrate was found. Crystals were ob-
tained at room temperature from dichloromethane-hexane mix-
ture. Yield (isolated): 0.11 g (10%). M.p. 206 °C (dec.). IR (KBr):
4.3. Synthesis of compound [(i-PrNH)P(l-N-t-Bu)2P(@N-i-Pr)-
N(CO2-i-Pr)-NH(CO2-i-Pr)] (24)
Cyclodiphosphazane [i-PrNHPN-t-Bu]2 [d(P) 90.69; 0.609 g,
1.9 mmol] was dissolved in dry toluene (6 mL). To this, diisopropyl
azodicarboxylate (0.384 g, 1.9 mmol) was added drop-wise at
25 °C. The mixture was stirred for 1 d, concentrated in vacuo (to
ca 2 mL) and cooled for 1 d at ꢀ4 °C to obtain crystals of [(i-
3208, 3102, 2971, 2241, 1493, 1454, 1367, 1196 cm–1 1H NMR
.
(400 MHz, CDCl3): d 1.35, 1.38, 1.52, 1.68 (4 s, 36H, C(CH3)3),
2.82 (br m, 2H, PCH2), 3.02 (br m, 3H, PCCH + PCCCH2), 3.38 (br,
1H, NH), 7.25–7.37 (m, 5H, Ar–H), 8.10 (br, 1H, NH) (C–OH proton
peak was too broad). 13C NMR (100 MHz, CDCl3): d 26.6 (s, PCCH),
30.9 (d, 1J(P–C) ꢂ 121.0 Hz, PC, one of the peaks merged with peaks
due to t-Bu carbons), 31.1, 31.4 (2 s, C(CH3)3), 32.5 (d, 3J(P–C) ꢂ
10.0 Hz, C(CH3)3), 40.4 (d, 3J(P–C) = 15.0 Hz, CH2Ph), 52.9–56.1
(many lines, C(CH3)3), 120.0 (s, CN), 128.1, 129.2, 129.6, 134.9
(the peak due to bicarbonate was too weak to be observed). 31P
NMR (160 MHz, CDCl3): d 21.4, 88.0. Anal. Calc. for C27H49N5O3P2:
C, 58.57; H, 8.92; N, 12.64. Found: C, 58.72; H, 8.81; N, 12.66%.
CCDC number 749651.
PrNH)P(
l
-N-t-Bu)2P(@N-i-Pr)-N(CO2-i-Pr)-NH(CO2-i-Pr)]
(24).
Yield: 0.885 g (89%). M. p.: 105–108 °C. IR (KBr): 3339, 2980,
2733, 2602, 1747, 1716, 1498, 1369, 1304, 1205, 1107, 920,
869 cmꢀ1 1H NMR (400 MHz, CDCl3): d 1.14–1.44 (br, 42H,
.
(C(CH3)2 + C(CH3)3), 2.23 (d, 2J(P–H) = 4.4 Hz, 1H, NH-i-Pr), 3.54–
3.67 (m, 2H, NCH(CH3)2), 4.90–4.98 (m, 2H, OCH(CH3)2), 6.83 (1s,
1H, NH–C(O)). 13C NMR (100 MHz, CDCl3): d 21.87, 21.99, 22.12,
22.29, 26.08, 26.64, 27.55, 27.75, 30.88 (s, C(CH3)2 + C(CH3)3),
43.46, 50.84, 52.44, 52.74, 53.11, 67.28, 68.47, 69.33, 69.98,
153.82 (d, 2J(P–C) = 15.4 Hz, P–N–C(O)), 159.23 (P–N–N–C(O)).
31P NMR (160 MHz, CDCl3): d ꢀ6.89, 73.38. LC–MS: m/z 523
[M+1]+. Anal. Calc. for C22H48N6O4P2: C, 50.56; H, 9.26; N, 16.08.
Found: C, 50.48; H, 9.22; N, 16.17%. CCDC number 749653.
Compound [(t-BuNH)((CN)CH2CH2-)P(
l
-N-t-Bu)2P(NH-t-Bu)]+
-N-
[HCO3]ꢀ (14) was obtained by passing compound (t-Bu-NH)P(
l
t-Bu)2P(@N-t-Bu)(CH2CH2CN) (11) through a silica gel column using
ethyl acetate–hexane (9:1) mixture as eluent. Yield: 0.59 g (90%).
M.p.: 182–183 °C (dec.). IR (KBr): 3451, 3216, 2974, 2249, 1370,
4.4. Synthesis of compound [(S)-(2-OH-1-C10H6-10-C10H6-20-O-
P(O)(NH-t-Bu)2] (36)
1198 cm–1 1H NMR (400 MHz, CDCl3): d 1.34, 1.46, 1.52 (3s, 36H,
.
C(CH3)3), 2.38 (br, 2H, PCH2CH2), 3.05 (br, 2H, PCH2), 3.35 (br, ꢂ1H,
NH), the other NH and C–OH proton peaks were too broad. 13C
NMR (100 MHz, CDCl3): d 9.9 (s, PCCH2), 23.4 (d, 1J(P–C) = 97.0 Hz,
PC), 31.8, 32.3, 32.5 (3 s, C(CH3)3), 53.0 (d, 2J(P–C) = 15.0 Hz,
C(CH3)3), 54.7 and 56.1 (2 s, C(CH3)3), 117.5 (s, CN) (The peak due
to bicarbonate was perhaps too weak to be observed). 31P NMR
(160 MHz, CDCl3): d 21.1, 83.4. Anal. Calc. for C20H43N5O3P2: C,
51.79; H, 9.34; N, 15.17. Found: C, 51.86; H, 9.32; N, 15.08%.
To a solution of (S)-(1,10-O-C10H6-C10H6-O-)[(O)P(
l-N-t-Bu)2P(O)]
(32) (0.258 g, 0.50 mmol) in toluene, BH3.SMe2 (0.200 g, 2.7 mmol)
was added via syringe. This mixture was stirred for 30 min and then
the acetophenone (0.300 g, 2.5 mmol) was added. The contents were
stirred for 8 h more. The reaction mixture was quenched with water
and extracted with dichloromethane. The alcohol PhCH(OH)(CH3)
[0.270 g (90%)] was isolated using column chromatography (EtOAc-
hexane); from later fractions, compound [(S)-(2-OH-1-C10H6-10-
C10H6-20-O-P(O)(NH-t-Bu)2] (36) was isolated. Crystals of (S)-36
were obtained from 1:1 CH2Cl2–hexane. Yield: 0.156 g (60%). M.p.:
238–240 °C. IR (KBr): 3382, 3310, 2967, 1622, 1595, 1507, 1462,
4.2. Synthesis of compound [(t-BuNH)P(l-N-t-Bu)2P(@N-t-Bu)-
C(@CH2)CH(C6H4-4-Me)-P(O)(OCH2CMe2CH2O)] (18)
1387, 1209, 1161, 1067 cmꢀ1 1H NMR (400 MHz, CDCl3): d 0.99
.
Cyclodiphosphazane [(t-BuNH)P(l-N-t-Bu)]2 (6) (0.484 g,
and 1.05 (2 s, 18H, t-Bu-H), 2.24 and 2.30 (2 d, 2J(PH) = 8.0 Hz each,
2H, 2 NH-t-Bu), 6.80 (s, br, 1H, –OH), 7.07 (d, 3J(HH) = 8.0 Hz, 2H, Ar–
1.38 mmol) and allenylphosphonate
(OCH2CMe2CH2O)-

1050
K.C. Kumara Swamy et al. / Journal of Organometallic Chemistry 695 (2010) 1042–1051
Table 1
Crystallographic data for the compounds 13, 18, 24, 36 and 40.a
Compound
13
18
24
36
40
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
C27H49N5O3P2
553.67
Monoclinic
P21/n
10.4784(15)
17.994(3)
16.762(5)
90
94.75(4)
90
C31H47N4O3P3
626.72
C22H48N6O4P2
522.60
Monoclinic
P21/n
10.786(3)
16.708(4)
17.788(4)
90
104.188(4)
90
C28H33N2O3P
561.46
C17H35N3O2P2
375.42
Monoclinic
P21/n
9.4506(8)
13.7169(12)
16.9175(14)
90
96.5510(10)
90
Triclinic
Orthorhombic
P212121
9.8138(6)
14.8809(9)
20.8118(13)
90
90
90
3039.3(3)
4
1.227
ꢀ
P1
10.3463(7)
10.7424(7)
16.4625(11)
87.232(2)
89.947(3)
82.1340(10)
1810.3(2)
2
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V /Å3
3149.5(12)
4
1.166
3107.9(13)
4
1.117
2178.7(3)
4
1.145
Z
Dcalc (g cmꢀ3
)
1.150
0.199
l
(mmꢀ1
)
0.172
0.174
0.297
0.213
F(0 0 0)
1196
680
1136
1184
816
Data/restraints/parameters
GOF (S)
5534/0/342
1.079
7113/0/389
1.079
5425/0/329
1.055
7153/0/352
1.021
3838/12/296
1.048
R1 [I > 2
r
(I)]
0.0558
0.0684
0.0907
0.0577
0.0456
wR2 [all data]
0.1259
0.1672
0.694/ꢀ0.366
0.2244
0.671/ꢀ0.328
0.1546
0.383/ꢀ0.342
0.1323
0.269/ꢀ0.242
Max./min. residual elec. dens. [e Åꢀ3
]
0.272/ꢀ0.256
P
P
P
P
||Fo| ꢀ |Fc||/ |Fo| and wR2 = [ w(F2o ꢀ Fc2)2/ wFo4]0.5
.
a
R1
=
H), 7.22–7.99 (m, 10H, Ar–H). 13C NMR (400 MHz, CDCl3): d 31.0 and
31.2 (2 d, 3J(PC) ꢂ 4.7 Hz, C(CH3)3), 50.9 (d, 2J(PC) ꢂ 21.9 Hz C(CH3)3),
116.5, 119.6, 121.6, 121.7, 123.5, 124.7, 125.4, 125.6, 126.8, 127.0,
128.0, 128.1, 129.3, 130.0, 130.3, 131.2, 133.7, 148.7, 148.8, 152.4.
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a
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in these compounds have high thermal parameters, but these do
not affect the overall structure and hence we have not tried to
model these rigorously. Crystallographic data are summarized in
Table 1.
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(2006) 717.
We thank Department of Science and Technology (DST, New
Delhi) for financial support and equipment. We also thank UPE
program of the University Grants Commission (UGC, New Delhi)
for some equipment. GG, RRS, NNBK and MC thank Council of Sci-
entific and Industrial Research (CSIR, New Delhi) for fellowships.
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(2001) 685.
CCDC 749651, 749652, 749653, 749654 and 749655 contain the
supplementary crystallographic data for compounds 13, 18, 24, 36
and 40. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Center via www.ccdc.cam.ac.uk/da-
ta_request/cif. Supplementary data associated with this article
can be found, in the online version, at doi:10.1016/
j.jorganchem.2009.11.001.
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9819.

K.C. Kumara Swamy et al. / Journal of Organometallic Chemistry 695 (2010) 1042–1051
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